A new DOAS instrument on long-distance IAGOS-CARIBIC flights and airborne DOAS applications

NASA Astrophysics Data System (ADS)

Penth, Lara; Frieß, Udo; Pöhler, Denis; Platt, Ulrich; Zahn, Andreas

2017-04-01

Within the IAGOS-CARIBIC project airborne DOAS (Differential Optical Absorption Spectroscopy) measurements of atmospheric trace gases are performed aboard a commercial long range passenger aircraft from Lufthansa since 2005. They provide a unique dataset for episodic, long-term and seasonal observations. The DOAS instrument is the only remote sensing technique aboard. DOAS is a well-established remote sensing technique to retrieve trace gas columns in the atmosphere from scattered light spectra of the sun. A series of trace gas species can be observed simultaneously, including nitrogen dioxide (NO2), sulphur dioxide (SO2), bromine oxide (BrO), nitrous acid (HONO), formaldehyde (HCHO) and ozone (O3). Since DOAS is a contact-free measurement technique, it is specially well suited for measuring highly reactive trace gases. It is widely used on different platforms and the airborne DOAS measurements are filling the gap between ground-based measurements and satellite data. The CARIBIC DOAS instrument is divided into an instrument unit within the CARIBIC container in the cargo hold of the aircraft, a telescope unit, which is specially designed for the permanently mounted pylon underneath the aircraft, and fiber optics in between. The instrument unit consists of three temperature stabilized spectrometers and the readout and control electronics. The telescope unit contains three telescopes, which observe scattered sunlight to the right under the elevation angles of +10˚ , -10˚ and -82˚ (nadir) relative to the horizon. This measurement geometry allows the separation of boundary layer, free tropospheric and stratospheric trace gas columns along the flight track. A new DOAS instrument was designed and installed in 2016 (first flights expected from March 2017) to improve the detection limits of NO2, SO2, BrO, HCHO, HONO, O3 and O4. Furthermore, an extended wavelength range allows to measure in addition iodine monoxide (a potentially important oxidant in the free troposphere) and glyoxal (a tracer for VOCs). The IAGOS-CARIBIC project and the significant technical improvements of the new DOAS system will be presented. Also, selected examples for possible airborne measurement applications of the CARIBIC DOAS will be shown.

Scanning and mobile multi-axis DOAS measurements of SO2 and NO2 emissions from an electric power plant in Montevideo, Uruguay

NASA Astrophysics Data System (ADS)

Frins, E.; Bobrowski, N.; Osorio, M.; Casaballe, N.; Belsterli, G.; Wagner, T.; Platt, U.

2014-12-01

In March 2012 the emissions of NO2 and SO2 from a power station located on the east side of Montevideo Bay (34° 53‧ 10″ S, 56° 11‧ 49″ W) were quantified by simultaneously using mobile and scanning multi-axis differential optical absorption spectroscopy (in the following mobile DOAS and scanning DOAS, respectively). The facility produces electricity by means of two technologies: internal combustion motors and steam generators. The motors are powered with centrifuged heavy oil and produce a maximum power of 80 MW approximately. The steam generators produce approximately 305 MW and are powered with heavy fuel oil. We compare the emissions obtained from the measured slant column densities (mobile DOAS and scanning DOAS) with the emissions estimated from fuel mass balance. On one occasion it was possible to distinguish between the two types of sources, observing two plumes with different SO2 and NO2 emission rates. During the period of the campaign the mean SO2 emission flux was determined to be 0.36 (±0.12) kg s-1 and 0.26 (±0.09) kg s-1 retrieved from mobile and scanning DOAS respectively, while the calculated SO2 flux from the sulphur content of the fuel was 0.34 (±0.03) kg s-1. The average NO2 flux calculated from mobile DOAS was determined to be 11 (±3) × 10-3 kg s-1. Using the scanning DOAS approach a mean NO2 flux of 5.4 (±1.7) × 10-3 kg s-1 was obtained, which is significantly lower than by the mobile measurements. The differences between the results of mobile MAX-DOAS measurements and scanning DOAS measurements are most probably caused by the variability and the limited knowledge of the wind speed and direction.

Effects of Lactobacillus plantarum on production performance, immune characteristics, antioxidant status, and intestinal microflora of bursin-immunized broilers.

PubMed

Shen, Xuejiao; Yi, Dan; Ni, Xueqin; Zeng, Dong; Jing, Bo; Lei, Mingxia; Bian, Zhengrong; Zeng, Yan; Li, Tao; Xin, Jinge

2014-04-01

Examples of probiotics that can promote host health by improving its intestinal microbial balance and intestinal immunity belong to the genus Lactobacillus. Bursin (BS) is a peptide isolated from the bursa of Fabricius for use as an adjuvant for a variety of immunogens. To investigate the synergistic effects of Lactobacillus plantarum (LP) dietary supplementation and BS immunization on production performance, immune characteristics, antioxidant status, and intestinal microflora in broilers, we randomly allocated 200 1-day-old broilers of mixed sex into 4 treatments in a 2 × 2 factorial arrangement (LP-/BS-, LP-/BS+, LP+/BS-, LP+/BS+) for 42 days. BS immunization enhanced immune response by increasing serum total immunoglobulin G concentration and interleukin-6 concentration, promoted antioxidant capacity by increasing catalase activities in serum and liver and by decreasing serum malondialdehyde (MDA) content at 42 days of age (DOA), and enriched intestinal microflora diversity. LP supplementation enhanced immune response by increasing interleukin-2 concentration at 42 DOA; promoted antioxidant capacity by increasing liver catalase activities, increasing glutathione peroxidase activities in serum and liver at 21 DOA, and decreasing serum MDA content at 42 DOA; promoted intestinal microflora composition by decreasing total aerobes and Escherichia coli counts at 21 DOA, by increasing total anaerobes count at 21 DOA, and by increasing Lactobacillus spp. and Bifidobacterium spp. counts at both 21 and 42 DOA. The interactions between BS and LP had a significant effect on daily body mass gain and feed conversion ratio in the starter period (1-21 DOA); on interleukin-2 concentration and liver MDA content at 21 DOA; and on thymus index, peripheral lymphocyte proliferation, and E. coli counts at 42 DOA. Overall, these data suggest that the combination of LP dietary supplementation and BS immunization promoted the production performance, immune characteristics, antioxidant status, and intestinal microflora of broilers.

Five years of NO2 Mobile-DOAS measurements in Europe: an overview

NASA Astrophysics Data System (ADS)

Merlaud, Alexis; Fayt, Caroline; Pinardi, Gaia; Tack, Frederik; Hendrick, François; Le Roux, Anabel-Lise; Constantin, Daniel-Eduard; Voiculescu, Mirela; Shaiganfar, Reza; Wagner, Thomas; Van Roozendael, Michel

2014-05-01

Since the CINDI campaign held in the Netherlands in July 2009, BIRA-IASB has been operating a car-based mobile-DOAS system, primarily dedicated to tropospheric NO2 measurements. The instrument is based on two similar compact spectrometers and records scattered light spectra simultaneously in the zenith direction and 30° above the horizon, following the MAX-DOAS approach. After CINDI, Mobile-DOAS measurements were performed on a routine basis between March 2010 and August 2011, mostly across Belgium, but also in Luxembourg, France, and Germany. From 2011, another BIRA-IASB mobile-DOAS instrument, using a single zenith channel, was operated in Romania through a collaboration with the University of Galati. In June 2013, these two mobile-DOAS instruments took part in the MADCAT campaign in Mainz, Germany, together with the MPIC mobile-DOAS system, based on a mini MAX-DOAS. We describe the BIRA-IASB instruments, our strategy to retrieve the NO2 tropospheric column, and the large database that was constituted. The latter is particularly interesting for its size: it covers some 500 hours of measurements and 20 000 km, including rural, periurban and urban areas with different air quality conditions. A 2011 cloud-free subset of the measurements is compared with OMI data. We also present preliminary results of an intercomparison between the three mobile-DOAS instruments operated during MADCAT. The high spatial frequency of the measurements (around 100 m) makes them valuable to study the NO2 horizontal gradients in polluted areas. This has implications in the context of air quality satellite validation studies, in which the variability of NO2 inside a satellite pixel must be taken into account.

A Conserved C-terminal Element in the Yeast Doa10 and Human MARCH6 Ubiquitin Ligases Required for Selective Substrate Degradation*

PubMed Central

Zattas, Dimitrios; Berk, Jason M.; Kreft, Stefan G.; Hochstrasser, Mark

2016-01-01

Specific proteins are modified by ubiquitin at the endoplasmic reticulum (ER) and are degraded by the proteasome, a process referred to as ER-associated protein degradation. In Saccharomyces cerevisiae, two principal ER-associated protein degradation ubiquitin ligases (E3s) reside in the ER membrane, Doa10 and Hrd1. The membrane-embedded Doa10 functions in the degradation of substrates in the ER membrane, nuclear envelope, cytoplasm, and nucleoplasm. How most E3 ligases, including Doa10, recognize their protein substrates remains poorly understood. Here we describe a previously unappreciated but highly conserved C-terminal element (CTE) in Doa10; this cytosolically disposed 16-residue motif follows the final transmembrane helix. A conserved CTE asparagine residue is required for ubiquitylation and degradation of a subset of Doa10 substrates. Such selectivity suggests that the Doa10 CTE is involved in substrate discrimination and not general ligase function. Functional conservation of the CTE was investigated in the human ortholog of Doa10, MARCH6 (TEB4), by analyzing MARCH6 autoregulation of its own degradation. Mutation of the conserved Asn residue (N890A) in the MARCH6 CTE stabilized the normally short lived enzyme to the same degree as a catalytically inactivating mutation (C9A). We also report the localization of endogenous MARCH6 to the ER using epitope tagging of the genomic MARCH6 locus by clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated genome editing. These localization and CTE analyses support the inference that MARCH6 and Doa10 are functionally similar. Moreover, our results with the yeast enzyme suggest that the CTE is involved in the recognition and/or ubiquitylation of specific protein substrates. PMID:27068744

The application of UV LEDs for differential optical absorption spectroscopy

NASA Astrophysics Data System (ADS)

Geiko, Pavel P.; Smirnov, Sergey S.; Samokhvalov, Ignatii V.

2018-04-01

Modern UV LEDs represent a potentially very advantageous alternative to thermal light sources, in particular xenon arc lamps, which are the most common light sources in trace gas-analyzers. So, the light-emitting diodes are very attractive for use of as light sources for Long Path Differential Optical Absorption Spectroscopy (DOAS) measurements of trace gases in the open atmosphere. Recent developments in fibre-coupling telescope technology and the availability of ultraviolet light emitting diodes have now allowed us to construct a portable, long path DOAS instrument for use at remote locations and specifically for measuring degassing from active volcanic systems. First of all, we are talking about the measurement of sulphur dioxide, carbon disulphide and, oxides of chlorine and bromine. The parallel measurements of sulfur dioxide using a certified gas analyzer, were conducted and showed good correlation.

On the absolute calibration of SO2 cameras

USGS Publications Warehouse

Lübcke, Peter; Bobrowski, Nicole; Illing, Sebastian; Kern, Christoph; Alvarez Nieves, Jose Manuel; Vogel, Leif; Zielcke, Johannes; Delgados Granados, Hugo; Platt, Ulrich

2013-01-01

This work investigates the uncertainty of results gained through the two commonly used, but quite different, calibration methods (DOAS and calibration cells). Measurements with three different instruments, an SO2 camera, a NFOVDOAS system and an Imaging DOAS (I-DOAS), are presented. We compare the calibration-cell approach with the calibration from the NFOV-DOAS system. The respective results are compared with measurements from an I-DOAS to verify the calibration curve over the spatial extent of the image. The results show that calibration cells, while working fine in some cases, can lead to an overestimation of the SO2 CD by up to 60% compared with CDs from the DOAS measurements. Besides these errors of calibration, radiative transfer effects (e.g. light dilution, multiple scattering) can significantly influence the results of both instrument types. The measurements presented in this work were taken at Popocatepetl, Mexico, between 1 March 2011 and 4 March 2011. Average SO2 emission rates between 4.00 and 14.34 kg s−1 were observed.

Human performance consequences of stages and levels of automation: an integrated meta-analysis.

PubMed

Onnasch, Linda; Wickens, Christopher D; Li, Huiyang; Manzey, Dietrich

2014-05-01

We investigated how automation-induced human performance consequences depended on the degree of automation (DOA). Function allocation between human and automation can be represented in terms of the stages and levels taxonomy proposed by Parasuraman, Sheridan, and Wickens. Higher DOAs are achieved both by later stages and higher levels within stages. A meta-analysis based on data of 18 experiments examines the mediating effects of DOA on routine system performance, performance when the automation fails, workload, and situation awareness (SA). The effects of DOA on these measures are summarized by level of statistical significance. We found (a) a clear automation benefit for routine system performance with increasing DOA, (b) a similar but weaker pattern for workload when automation functioned properly, and (c) a negative impact of higher DOA on failure system performance and SA. Most interesting was the finding that negative consequences of automation seem to be most likely when DOA moved across a critical boundary, which was identified between automation supporting information analysis and automation supporting action selection. Results support the proposed cost-benefit trade-off with regard to DOA. It seems that routine performance and workload on one hand, and the potential loss of SA and manual skills on the other hand, directly trade off and that appropriate function allocation can serve only one of the two aspects. Findings contribute to the body of research on adequate function allocation by providing an overall picture through quantitatively combining data from a variety of studies across varying domains.

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Science.gov Websites

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Performance assessment of radiant cooling system integrated with desiccant assisted DOAS with solar regeneration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, Yasin; Singh, Gaurav; Mathur, Jyotirmay

The Radiant cooling system integrated with Dedicated Outdoor Air System (DOAS) is a viable substitution for conventional all air system in order to reduce primary energy consumption, as it decouples the cooling and ventilation task. In DOAS major portion of energy is consumed in cooling coil where it dehumidifies the process supply air. This study describes an alternate solution for dehumidification, with the substitution of the desiccant wheel with solar regeneration in place of a chilled water coil based dehumidifier. In this paper, simulations were carried out using EnergyPlus on a reference medium office building to investigate the contribution ofmore » solar energy towards the total energy consumption of desiccant assisted DOAS with radiant cooling system. To evaluate the system performance and energy saving potential, desiccant based DOAS is compared with cooling coil assisted DOAS integrated with Radiant cooling system. Simulations were carried out for different solar collector area to evaluate primary energy savings. Results indicate that from 7.4 % to 28.6 % energy saving (according to different collector area) can be achieved due to the solar regeneration in desiccant assisted DOAS, the impact of different solar collector area on potential of energy savings is also described.« less

Performance assessment of radiant cooling system integrated with desiccant assisted DOAS with solar regeneration

DOE PAGES

Khan, Yasin; Singh, Gaurav; Mathur, Jyotirmay; ...

2017-06-13

The Radiant cooling system integrated with Dedicated Outdoor Air System (DOAS) is a viable substitution for conventional all air system in order to reduce primary energy consumption, as it decouples the cooling and ventilation task. In DOAS major portion of energy is consumed in cooling coil where it dehumidifies the process supply air. This study describes an alternate solution for dehumidification, with the substitution of the desiccant wheel with solar regeneration in place of a chilled water coil based dehumidifier. In this paper, simulations were carried out using EnergyPlus on a reference medium office building to investigate the contribution ofmore » solar energy towards the total energy consumption of desiccant assisted DOAS with radiant cooling system. To evaluate the system performance and energy saving potential, desiccant based DOAS is compared with cooling coil assisted DOAS integrated with Radiant cooling system. Simulations were carried out for different solar collector area to evaluate primary energy savings. Results indicate that from 7.4 % to 28.6 % energy saving (according to different collector area) can be achieved due to the solar regeneration in desiccant assisted DOAS, the impact of different solar collector area on potential of energy savings is also described.« less

Research on an estimation method of DOA for wireless location based on TD-SCDMA

NASA Astrophysics Data System (ADS)

Zhang, Yi; Luo, Yuan; Cheng, Shi-xin

2004-03-01

To meet the urgent need of personal communication and hign-speed data services,the standardization and products development for International Mobile Telecommunication-2000 (IMT-2000) have become a hot point in wordwide. The wireless location for mobile terminals has been an important research project. Unlike GPS which is located by 24 artificial satellities, it is based on the base-station of wireless cell network, and the research and development of it are correlative with IMT-2000. While the standard for the third generation mobile telecommunication (3G)-TD-SCDMA, which is proposed by China and the intellective property right of which is possessed by Chinese, is adopted by ITU-T at the first time, the research for wireless location based on TD-SCDMA has theoretic meaning, applied value and marketable foreground. First,the basic principle and method for wireless location, i.e. Direction of Angle(DOA), Time of Arrival(TOA) or Time Difference of Arrival(TDOA), hybridized location(TOA/DOA,TDOA/DOA,TDOA/DOA),etc. is introduced in the paper. So the research of DOA is very important in wireless location. Next, Main estimation methods of DOA for wireless location, i.e. ESPRIT, MUSIC, WSF, Min-norm, etc. are researched in the paper. In the end, the performances of DOA estimation for wireless location based on mobile telecommunication network are analyzed by the research of theory and simulation experiment and the contrast algorithms between and Cramer-Rao Bound. Its research results aren't only propitious to the choice of algorithms for wireless location, but also to the realization of new service of wireless location .

A Conserved C-terminal Element in the Yeast Doa10 and Human MARCH6 Ubiquitin Ligases Required for Selective Substrate Degradation.

PubMed

Zattas, Dimitrios; Berk, Jason M; Kreft, Stefan G; Hochstrasser, Mark

2016-06-03

Specific proteins are modified by ubiquitin at the endoplasmic reticulum (ER) and are degraded by the proteasome, a process referred to as ER-associated protein degradation. In Saccharomyces cerevisiae, two principal ER-associated protein degradation ubiquitin ligases (E3s) reside in the ER membrane, Doa10 and Hrd1. The membrane-embedded Doa10 functions in the degradation of substrates in the ER membrane, nuclear envelope, cytoplasm, and nucleoplasm. How most E3 ligases, including Doa10, recognize their protein substrates remains poorly understood. Here we describe a previously unappreciated but highly conserved C-terminal element (CTE) in Doa10; this cytosolically disposed 16-residue motif follows the final transmembrane helix. A conserved CTE asparagine residue is required for ubiquitylation and degradation of a subset of Doa10 substrates. Such selectivity suggests that the Doa10 CTE is involved in substrate discrimination and not general ligase function. Functional conservation of the CTE was investigated in the human ortholog of Doa10, MARCH6 (TEB4), by analyzing MARCH6 autoregulation of its own degradation. Mutation of the conserved Asn residue (N890A) in the MARCH6 CTE stabilized the normally short lived enzyme to the same degree as a catalytically inactivating mutation (C9A). We also report the localization of endogenous MARCH6 to the ER using epitope tagging of the genomic MARCH6 locus by clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated genome editing. These localization and CTE analyses support the inference that MARCH6 and Doa10 are functionally similar. Moreover, our results with the yeast enzyme suggest that the CTE is involved in the recognition and/or ubiquitylation of specific protein substrates. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

LED-CE-DOAS measurements of NO2: intercomparison with CaRDS

NASA Astrophysics Data System (ADS)

Thalman, R. M.; Washenfelder, R.; Brown, S. S.; Volkamer, R.

2009-04-01

The combination of cavity enhanced absorption spectroscopy (CEAS) with Light Emitting Diode (LED) light sources lends itself to the application of the well established Differential Optical Absorption Spectroscopy (DOAS) technique (LED-CE-DOAS). In contrast to other broad band CEAS (BB-CEAS) techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e., does not require knowledge of the light intensity in the absence of trace gases (I0). With CE-DOAS there is no necessity for sampling lines to supply air samples into a cavity, or filters to remove aerosols from the airstream, as measurements are possible in a cavity that can be open to the atmosphere. A novel LED-CE-DOAS instrument was built at CU Boulder for the sensitive and selective detection of nitrogen dioxide (NO2), glyoxal (CHOCHO), iodine oxide (IO), water, and oxygen dimers (O4). CU Boulder's LED-CE-DOAS instrument was collocated to NOAA's NO2 Cavity Ring Down (CaRDS) instrument to test different CE-DOAS data retrieval algorithms for NO2 and O4. Both instruments were collocated to sample known NO2 concentrations from the same gas manifold, and to sample atmospheric air in a parking lot. This contribution focuses on the instrument components, challenges and means to retrieve quantitative concentrations of NO2 by LED-CE-DOAS, i.e., the distortion of NO2 and O4 absorption features due to different effective path lengths induced by (1) changes in the mirror reflectivity with wavelength, and (2) changes in light extinction across the absorption bands due to differential trace gas absorption features. We demonstrate that simultaneous measurements of O4 and NO2 enable to characterize the effective pathlength in the absence and presence of NO2 and perform absolute measurements based only on relative intensity measurements. To our knowledge these are the first CEAS measurements that rely solely on relative intensity measurements.

NOx emissions of various sources in Romania and the Rhein-Main region in Germany based on mobile MAX-DOAS measurements of NO2.

NASA Astrophysics Data System (ADS)

Riffel, Katharina; Sebastian, Donner; Shaiganfar, Reza; Wagner, Thomas; Dörner, Steffen

2016-04-01

The MAX DOAS-Method (Multi-AXis Differential Optical Absorption Spectroscopy) is used to analyze different trace gases (e.g. NO2, SO2, HCHO) at the same time and to determine the trace gas vertical column density (vertically integrated concentration). In summer 2015 we performed car-MAX-DOAS measurements in Romania during the AROMAT2 campaign. We encircled Bucharest at different weather situations and different times of the day. Afterwards the total NOx emissions were derived from the mobile MAX-DOAS observations in combination with wind data. In Germany we performed the same measurement procedure in fall/ winter/ spring 2015 /2016 by encircling the cities Mainz and Frankfurt. For the setting we mounted two MAX-DOAS instruments with different viewing directions (forward and backward) on the roof of a car. One instrument is a commercial mini MAX-DOAS that is built by the German company Hoffmann Messtechnik. The second one was built at the MPI in Mainz. This so-called Tube MAX-DOAS uses an AVANTES spectrometer with better optical characteristics than Hoffmann's mini MAX-DOAS. The advantage of two instruments working at the same time is (besides redundancy) that localized emission plumes can be measured from different directions at different locations. Thus, especially for emission plumes from power plants, tomographic methods can be applied to derive information about the plume altitude. Car-MAX-DOAS observations can cover large areas at a short time with reasonable resolution (depending on the speed of the car and the instruments integration time). Thus these measurements are well suited to validate satellites observations. This work will show the first AROMAT2 results of NOx emissions derived in Romania and in the Rhein-Main region, which is one of the most polluted area in Germany.

DOAS (differential optical absorption spectroscopy) urban pollution measurements

NASA Astrophysics Data System (ADS)

Stevens, Robert K.; Vossler, T. L.

1991-05-01

During July and August of 1990, a differential optical absorption spectrometer (DOAS) made by OPSIS Inc. was used to measure gaseous air pollutants over three separate open paths in Atlanta, GA. Over path 1 (1099 m) and path 2 (1824 m), ozone (03), sulfur dioxide (SO2) nitrogen dioxide (NO2), nitrous acid (HNO2) formaldehyde (HCHO), benzene, toluene, and o-xylene were measured. Nitric oxide (NO) and ammonia (NH3) were monitored over path 3 (143 m). The data quality and data capture depended on the compound being measured and the path over which it was measured. Data quality criteria for each compound were chosen such that the average relative standard deviation would be less than 25%. Data capture ranged from 43% for o-xylene for path 1 to 95% for ozone for path 2. Benzene, toluene, and o-xylene concentrations measured over path 2, which crossed over an interstate highway, were higher than concentrations measured over path 1, implicating emissions from vehicles on the highway as a significant source of these compounds. Federal Reference Method (FRN) instruments were located near the DOAS light receivers and measurements of 03, NO2, and NO were made concurrently with the DOAS. Correlation coefficients greater than 0.85 were obtained between the DOAS and FRM's; however, there was a difference between the mean values obtained by the two methods for 03 and NO. A gas chromatograph for measuring volatile organic compounds was operated next to the FRN's. Correlation coefficients of about 0.66 were obtained between the DOAS and GC measurements of benzene and o- xylene. However, the correlation coefficient between the DOAS and GC measurements of toluene averaged only 0.15 for the two DOAS measurement paths. The lack of correlation and other factors indicate the possibility of a localized source of toluene near the GC. In general, disagreements between the two measurement methods could be caused by atmospheric inhomogeneities or interferences in the DOAS and other methods.

Formation of a bioconjugate composed of hemin, smectite, and quaternary ammonium chloride that is soluble and active in hydrophobic media.

PubMed

Kurosawa, Masaru; Itoh, Tetsuji; Kodera, Yoh; Matsushima, Ayako; Hiroto, Misao; Nishimura, Hiroyuki; Inada, Yuji

2002-01-01

Hemin (Fe(3+)) was adsorbed onto synthetic smectite (clay mineral) intercalated with a quaternary alkenylammonium compound, dioleyldimethylammonium chloride (DOA), to form a hemin-smectite-DOA conjugate. The hemin-smectite-DOA conjugate was soluble in organic solvents such as benzene and toluene to form a transparent colloidal solution with a light yellow color. Its absorption spectrum in benzene showed two bands, 600 and 568 nm, in the visible region and a sharp Soret band at 400 nm with the molar extinction coefficient of 7.5 x 10(4) M(-1) cm(-1). The formation of the conjugate of smectite and DOA was confirmed by X-ray diffraction analysis: the basal spacing, d(001), of hemin-smectite-DOA conjugate was 19 A which is an expansion of the interlayer space by 5 A based upon the basal spacing of smectite of 14 A. Hemin-smectite-DOA conjugate catalyzed the peroxidase-like reaction in organic solvents using benzoyl peroxide as the hydrogen acceptor and leucocrystal violet as the hydrogen donor. The temperature-dependent peroxidase-like activity of the conjugate was compared with peroxidase activity of horseradish peroxidase. The hemin-smectite-DOA conjugate exhibited higher activity as the temperature was increased from 30 to 70 degrees C, while horseradish peroxidase activity was reduced as the temperature was increased.

DOA-informed source extraction in the presence of competing talkers and background noise

NASA Astrophysics Data System (ADS)

Taseska, Maja; Habets, Emanuël A. P.

2017-12-01

A desired speech signal in hands-free communication systems is often degraded by noise and interfering speech. Even though the number and locations of the interferers are often unknown in practice, it is justified to assume in certain applications that the direction-of-arrival (DOA) of the desired source is approximately known. Using the known DOA, fixed spatial filters such as the delay-and-sum beamformer can be steered to extract the desired source. However, it is well-known that fixed data-independent spatial filters do not provide sufficient reduction of directional interferers. Instead, the DOA information can be used to estimate the statistics of the desired and the undesired signals and to compute optimal data-dependent spatial filters. One way the DOA is exploited for optimal spatial filtering in the literature, is by designing DOA-based narrowband detectors to determine whether a desired or an undesired signal is dominant at each time-frequency (TF) bin. Subsequently, the statistics of the desired and the undesired signals can be estimated during the TF bins where the respective signal is dominant. In a similar manner, a Gaussian signal model-based detector which does not incorporate DOA information has been used in scenarios where the undesired signal consists of stationary background noise. However, when the undesired signal is non-stationary, resulting for example from interfering speakers, such a Gaussian signal model-based detector is unable to robustly distinguish desired from undesired speech. To this end, we propose a DOA model-based detector to determine the dominant source at each TF bin and estimate the desired and undesired signal statistics. We demonstrate that data-dependent spatial filters that use the statistics estimated by the proposed framework achieve very good undesired signal reduction, even when using only three microphones.

Extra-virgin olive oil contains a metabolo-epigenetic inhibitor of cancer stem cells

PubMed Central

Corominas-Faja, Bruna; Cuyàs, Elisabet; Lozano-Sánchez, Jesús; Cufí, Sílvia; Verdura, Sara; Fernández-Arroyo, Salvador; Borrás-Linares, Isabel; Martin-Castillo, Begoña; Martin, Ángel G; Lupu, Ruth; Nonell-Canals, Alfons; Micol, Vicente; Joven, Jorge; Segura-Carretero, Antonio; Menendez, Javier A

2018-01-01

Abstract Targeting tumor-initiating, drug-resistant populations of cancer stem cells (CSC) with phytochemicals is a novel paradigm for cancer prevention and treatment. We herein employed a phenotypic drug discovery approach coupled to mechanism-of-action profiling and target deconvolution to identify phenolic components of extra virgin olive oil (EVOO) capable of suppressing the functional traits of CSC in breast cancer (BC). In vitro screening revealed that the secoiridoid decarboxymethyl oleuropein aglycone (DOA) could selectively target subpopulations of epithelial-like, aldehyde dehydrogenase (ALDH)-positive and mesenchymal-like, CD44+CD24−/low CSC. DOA could potently block the formation of multicellular tumorspheres generated from single-founder stem-like cells in a panel of genetically diverse BC models. Pretreatment of BC populations with noncytotoxic doses of DOA dramatically reduced subsequent tumor-forming capacity in vivo. Mice orthotopically injected with CSC-enriched BC-cell populations pretreated with DOA remained tumor-free for several months. Phenotype microarray-based screening pointed to a synergistic interaction of DOA with the mTOR inhibitor rapamycin and the DNA methyltransferase (DNMT) inhibitor 5-azacytidine. In silico computational studies indicated that DOA binds and inhibits the ATP-binding kinase domain site of mTOR and the S-adenosyl-l-methionine (SAM) cofactor-binding pocket of DNMTs. FRET-based Z-LYTE™ and AlphaScreen-based in vitro assays confirmed the ability of DOA to function as an ATP-competitive mTOR inhibitor and to block the SAM-dependent methylation activity of DNMTs. Our systematic in vitro, in vivo and in silico approaches establish the phenol-conjugated oleoside DOA as a dual mTOR/DNMT inhibitor naturally occurring in EVOO that functionally suppresses CSC-like states responsible for maintaining tumor-initiating cell properties within BC populations. PMID:29452350

Spiral-shaped piezoelectric sensors for Lamb waves direction of arrival (DoA) estimation

NASA Astrophysics Data System (ADS)

De Marchi, L.; Testoni, N.; Marzani, A.

2018-04-01

A novel strategy to design piezoelectric sensors suited for direction of arrival (DoA) estimation of incoming Lamb waves is presented in this work. The designed sensor is composed by two piezoelectric patches (P1, P2) bonded on the structure to be inspected. In particular, by exploiting the Radon transform, the proposed procedure computes the shape of P2 given the shape of P1 so that the difference in time of arrival (DToA) of the Lamb waves at the two patches is linearly related to the DoA while being agnostic of the waveguide dispersion curves. With a dedicated processing procedure, the waveforms acquired from the two electrodes and digitized can be used to retrieve the DoA information. Numerical and experimental results show that DoA estimation performed by means of the proposed shaped transducers is extremely robust.

Radar velocity determination using direction of arrival measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doerry, Armin W.; Bickel, Douglas L.; Naething, Richard M.

The various technologies presented herein relate to utilizing direction of arrival (DOA) data to determine various flight parameters for an aircraft A plurality of radar images (e.g., SAR images) can be analyzed to identify a plurality of pixels in the radar images relating to one or more ground targets. In an embodiment, the plurality of pixels can be selected based upon the pixels exceeding a SNR threshold. The DOA data in conjunction with a measurable Doppler frequency for each pixel can be obtained. Multi-aperture technology enables derivation of an independent measure of DOA to each pixel based on interferometric analysis.more » This independent measure of DOA enables decoupling of the aircraft velocity from the DOA in a range-Doppler map, thereby enabling determination of a radar velocity. The determined aircraft velocity can be utilized to update an onboard INS, and to keep it aligned, without the need for additional velocity-measuring instrumentation.« less

A Novel DFT-Based DOA Estimation by a Virtual Array Extension Using Simple Multiplications for FMCW Radar

PubMed Central

Kim, Bongseok; Kim, Sangdong; Lee, Jonghun

2018-01-01

We propose a novel discrete Fourier transform (DFT)-based direction of arrival (DOA) estimation by a virtual array extension using simple multiplications for frequency modulated continuous wave (FMCW) radar. DFT-based DOA estimation is usually employed in radar systems because it provides the advantage of low complexity for real-time signal processing. In order to enhance the resolution of DOA estimation or to decrease the missing detection probability, it is essential to have a considerable number of channel signals. However, due to constraints of space and cost, it is not easy to increase the number of channel signals. In order to address this issue, we increase the number of effective channel signals by generating virtual channel signals using simple multiplications of the given channel signals. The increase in channel signals allows the proposed scheme to detect DOA more accurately than the conventional scheme while using the same number of channel signals. Simulation results show that the proposed scheme achieves improved DOA estimation compared to the conventional DFT-based method. Furthermore, the effectiveness of the proposed scheme in a practical environment is verified through the experiment. PMID:29758016

Accurately determining direction of arrival by seismic array based on compressive sensing

NASA Astrophysics Data System (ADS)

Hu, J.; Zhang, H.; Yu, H.

2016-12-01

Seismic array analysis method plays an important role in detecting weak signals and determining their locations and rupturing process. In these applications, reliably estimating direction of arrival (DOA) for the seismic wave is very important. DOA is generally determined by the conventional beamforming method (CBM) [Rost et al, 2000]. However, for a fixed seismic array generally the resolution of CBM is poor in the case of low-frequency seismic signals, and in the case of high frequency seismic signals the CBM may produce many local peaks, making it difficult to pick the one corresponding to true DOA. In this study, we develop a new seismic array method based on compressive sensing (CS) to determine the DOA with high resolution for both low- and high-frequency seismic signals. The new method takes advantage of the space sparsity of the incoming wavefronts. The CS method has been successfully used to determine spatial and temporal earthquake rupturing distributions with seismic array [Yao et al, 2011;Yao et al, 2013;Yin 2016]. In this method, we first form the problem of solving the DOA as a L1-norm minimization problem. The measurement matrix for CS is constructed by dividing the slowness-angle domain into many grid nodes, which needs to satisfy restricted isometry property (RIP) for optimized reconstruction of the image. The L1-norm minimization is solved by the interior point method. We first test the CS-based DOA array determination method on synthetic data constructed based on Shanghai seismic array. Compared to the CBM, synthetic test for data without noise shows that the new method can determine the true DOA with a super-high resolution. In the case of multiple sources, the new method can easily separate multiple DOAs. When data are contaminated by noise at various levels, the CS method is stable when the noise amplitude is lower than the signal amplitude. We also test the CS method for the Wenchuan earthquake. For different arrays with different apertures, we are able to obtain reliable DOAs with uncertainties lower than 10 degrees.

Real-Valued Covariance Vector Sparsity-Inducing DOA Estimation for Monostatic MIMO Radar

PubMed Central

Wang, Xianpeng; Wang, Wei; Li, Xin; Liu, Jing

2015-01-01

In this paper, a real-valued covariance vector sparsity-inducing method for direction of arrival (DOA) estimation is proposed in monostatic multiple-input multiple-output (MIMO) radar. Exploiting the special configuration of monostatic MIMO radar, low-dimensional real-valued received data can be obtained by using the reduced-dimensional transformation and unitary transformation technique. Then, based on the Khatri–Rao product, a real-valued sparse representation framework of the covariance vector is formulated to estimate DOA. Compared to the existing sparsity-inducing DOA estimation methods, the proposed method provides better angle estimation performance and lower computational complexity. Simulation results verify the effectiveness and advantage of the proposed method. PMID:26569241

Real-Valued Covariance Vector Sparsity-Inducing DOA Estimation for Monostatic MIMO Radar.

PubMed

Wang, Xianpeng; Wang, Wei; Li, Xin; Liu, Jing

2015-11-10

In this paper, a real-valued covariance vector sparsity-inducing method for direction of arrival (DOA) estimation is proposed in monostatic multiple-input multiple-output (MIMO) radar. Exploiting the special configuration of monostatic MIMO radar, low-dimensional real-valued received data can be obtained by using the reduced-dimensional transformation and unitary transformation technique. Then, based on the Khatri-Rao product, a real-valued sparse representation framework of the covariance vector is formulated to estimate DOA. Compared to the existing sparsity-inducing DOA estimation methods, the proposed method provides better angle estimation performance and lower computational complexity. Simulation results verify the effectiveness and advantage of the proposed method.

Hardware design and implementation of fast DOA estimation method based on multicore DSP

NASA Astrophysics Data System (ADS)

Guo, Rui; Zhao, Yingxiao; Zhang, Yue; Lin, Qianqiang; Chen, Zengping

2016-10-01

In this paper, we present a high-speed real-time signal processing hardware platform based on multicore digital signal processor (DSP). The real-time signal processing platform shows several excellent characteristics including high performance computing, low power consumption, large-capacity data storage and high speed data transmission, which make it able to meet the constraint of real-time direction of arrival (DOA) estimation. To reduce the high computational complexity of DOA estimation algorithm, a novel real-valued MUSIC estimator is used. The algorithm is decomposed into several independent steps and the time consumption of each step is counted. Based on the statistics of the time consumption, we present a new parallel processing strategy to distribute the task of DOA estimation to different cores of the real-time signal processing hardware platform. Experimental results demonstrate that the high processing capability of the signal processing platform meets the constraint of real-time direction of arrival (DOA) estimation.

Bond Length Equalization with molecular aromaticity-A new measurement of aromaticity.

PubMed

Shen, Chen-Fei; Liu, Zi-Zhong; Liu, Hong-Xia; Zhang, Hui-Qing

2018-05-08

A new method to measure the amount of aromaticity is presented through the process of Bond Length Equalization (BLE). Degree of Aromaticity (DOA), a two-dimensional intensive quantity including geometric and energetic factors, as a new measurement of aromaticity is proposed. The unique characteristic of DOA and the formation of DOA will be displayed. The calculation of the geometrical optimization, DOA, Nucleus Independent Chemical Shifts (NICS) and Ring Stretching Vibration Raman Spectroscopy Frequency (RSVRSF) for the aromatic ring molecules - G n H n m (G = C, Si, Ge, n = 3, 5-8, m = +1, -1, 0, +1, +2) were calculated using the method of Density Functional Theory (DFT). The correlation between radius angle and molecular energy is absolute quadratic in the process of BLE. As the increasing of the number of ring atoms, the value of DOA decreasing gradually, the aromaticity decreased gradually, which was a same conclusion as NICS and RSVRSF concluded. Copyright © 2018 Elsevier B.V. All rights reserved.

Distributed abnormalities of brain white matter architecture in patients with dominant optic atrophy and OPA1 mutations.

PubMed

Rocca, Maria A; Bianchi-Marzoli, Stefania; Messina, Roberta; Cascavilla, Maria Lucia; Zeviani, Massimo; Lamperti, Costanza; Milesi, Jacopo; Carta, Arturo; Cammarata, Gabriella; Leocani, Letizia; Lamantea, Eleonora; Bandello, Francesco; Comi, Giancarlo; Falini, Andrea; Filippi, Massimo

2015-05-01

Using advanced MRI techniques, we investigated the presence and topographical distribution of brain grey matter (GM) and white matter (WM) alterations in dominant optic atrophy (DOA) patients with genetically proven OPA1 mutation as well as their correlation with clinical and neuro-ophthalmologic findings. Nineteen DOA patients underwent neurological, neuro-ophthalmologic and brainstem auditory evoked potentials (BAEP) evaluations. Voxel-wise methods were applied to assess regional GM and WM abnormalities in patients compared to 20 healthy controls. Visual acuity was reduced in 16 patients. Six DOA patients (4 with missense mutations) had an abnormal I peripheral component (auditory nerve) at BAEP. Compared to controls, DOA patients had significant atrophy of the optic nerves (p < 0.0001). Voxel-based morphometry (VBM) analysis showed that, compared to controls, DOA patients had significant WM atrophy of the chiasm and optic tracts; whereas no areas of GM atrophy were found. Tract-based spatial statistics (TBSS) analysis showed that compared to controls, DOA patients had significantly lower mean diffusivity, axial and radial diffusivity in the WM of the cerebellum, brainstem, thalamus, fronto-occipital-temporal lobes, including the cingulum, corpus callosum, corticospinal tract and optic radiation bilaterally. No abnormalities of fractional anisotropy were detected. No correlations were found between volumetric and diffusivity abnormalities quantified with MRI and clinical and neuro-ophthalmologic measures of disease severity. Consistently with pathological studies, tissue loss in DOA patients is limited to anterior optic pathways reflecting retinal ganglion cell degeneration. Distributed abnormalities of diffusivity indexes might reflect abnormal intracellular mitochondrial morphology as well as alteration of protein levels due to OPA1 mutations.

Estimation of sulphur dioxide emission rate from a power plant based on the remote sensing measurement with an imaging-DOAS instrument

NASA Astrophysics Data System (ADS)

Chong, Jihyo; Kim, Young J.; Baek, Jongho; Lee, Hanlim

2016-10-01

Major anthropogenic sources of sulphur dioxide in the troposphere include point sources such as power plants and combustion-derived industrial sources. Spatially resolved remote sensing of atmospheric trace gases is desirable for better estimation and validation of emission from those sources. It has been reported that Imaging Differential Optical Absorption Spectroscopy (I-DOAS) technique can provide the spatially resolved two-dimensional distribution measurement of atmospheric trace gases. This study presents the results of I-DOAS observations of SO2 from a large power plant. The stack plume from the Taean coal-fired power plant was remotely sensed with an I-DOAS instrument. The slant column density (SCD) of SO2 was derived by data analysis of the absorption spectra of the scattered sunlight measured by an I-DOAS over the power plant stacks. Two-dimensional distribution of SO2 SCD was obtained over the viewing window of the I-DOAS instrument. The measured SCDs were converted to mixing ratios in order to estimate the rate of SO2 emission from each stack. The maximum mixing ratio of SO2 was measured to be 28.1 ppm with a SCD value of 4.15×1017 molecules/cm2. Based on the exit velocity of the plume from the stack, the emission rate of SO2 was estimated to be 22.54 g/s. Remote sensing of SO2 with an I-DOAS instrument can be very useful for independent estimation and validation of the emission rates from major point sources as well as area sources.

Sparsity-Aware DOA Estimation Scheme for Noncircular Source in MIMO Radar.

PubMed

Wang, Xianpeng; Wang, Wei; Li, Xin; Liu, Qi; Liu, Jing

2016-04-14

In this paper, a novel sparsity-aware direction of arrival (DOA) estimation scheme for a noncircular source is proposed in multiple-input multiple-output (MIMO) radar. In the proposed method, the reduced-dimensional transformation technique is adopted to eliminate the redundant elements. Then, exploiting the noncircularity of signals, a joint sparsity-aware scheme based on the reweighted l1 norm penalty is formulated for DOA estimation, in which the diagonal elements of the weight matrix are the coefficients of the noncircular MUSIC-like (NC MUSIC-like) spectrum. Compared to the existing l1 norm penalty-based methods, the proposed scheme provides higher angular resolution and better DOA estimation performance. Results from numerical experiments are used to show the effectiveness of our proposed method.

Risk assessment for drugs of abuse in the Dutch watercycle.

PubMed

van der Aa, Monique; Bijlsma, Lubertus; Emke, Erik; Dijkman, Ellen; van Nuijs, Alexander L N; van de Ven, Bianca; Hernández, Felix; Versteegh, Ans; de Voogt, Pim

2013-04-01

A screening campaign of drugs of abuse (DOA) and their relevant metabolites in the aqueous environment was performed in the Netherlands. The presence of DOA, together with the potential risks for the environment and the possible human exposure to these compounds through consumption of drinking water was investigated. Sewage water (influent and effluent), surface water of the rivers Rhine and Meuse, and drinking water (raw and finished) were analysed by four different laboratories using fully in-house validated methods for a total number of 34 DOA and metabolites. In this way, data reported for several compounds could also be confirmed by other laboratories, giving extra confidence to the results obtained in this study. In total 17 and 22 DOA were detected and quantified in influent and effluent sewage samples, respectively. The tranquilizers oxazepam and temazepam, and cocaine and its metabolite benzoylecgonine were found in high concentrations in sewage water. Nine compounds were possibly not efficiently removed during treatment and were detected in surface waters. The results indicated that substantial fractions of the total load of DOA and metabolites in the rivers Rhine and Meuse enter the Netherlands from abroad. For some compounds, loads appear to increase going downstream, which is caused by a contribution from Dutch sewage water effluents. As far as data are available, no environmental effects are expected of the measured DOA in surface waters. In raw water, three DOA were detected, whereas in only one finished drinking water out of the 17 tested, benzoylecgonine was identified, albeit at a concentration below the limit of quantification (<1 ng/L). Concentrations were well below the general signal value of 1 μg/L, which is specified for organic compounds of anthropogenic origin in the Dutch Drinking Water Act. Copyright © 2013 Elsevier Ltd. All rights reserved.

The spatial distribution of the reactive iodine species IO from simultaneous active and passive DOAS observations

NASA Astrophysics Data System (ADS)

Seitz, K.; Buxmann, J.; Pöhler, D.; Sommer, T.; Tschritter, J.; Neary, T.; O'Dowd, C.; Platt, U.

2010-03-01

We present investigations of the reactive iodine species (RIS) IO, OIO and I2 in a coastal region from a field campaign simultaneously employing active long path differential optical absorption spectroscopy (LP-DOAS) as well as passive multi-axis differential optical absorption spectroscopy (MAX-DOAS). The campaign took place at the Martin Ryan Institute (MRI) in Carna, County Galway at the Irish West Coast about 6 km south-east of the atmospheric research station Mace Head in summer 2007. In order to study the horizontal distribution of the trace gases of interest, we established two almost parallel active LP-DOAS light paths, the shorter of 1034 m length just crossing the intertidal area, whereas the longer one of 3946 m length also crossed open water during periods of low tide. In addition we operated two passive Mini-MAX-DOAS instruments with the same viewing direction. While neither OIO nor I2 could be unambiguously identified with any of the instruments, IO could be detected with active as well as passive DOAS. The IO column densities seen at both active LP-DOAS light paths are almost the same. Thus it can be concluded that coastal IO is almost exclusively located in the intertidal area, where we detected mixing ratios of up to 29±8.8 ppt (equivalent to pmol/mol). Nucleation events with particle concentrations of 106 cm-3 particles were observed each day correlating with high IO mixing ratios. Therefore we feel that our detected IO concentrations confirm the results of model studies, which state that in order to explain such particle bursts, IO mixing ratios of 50 to 100 ppt in so called "hot-spots" are required.

The spatial distribution of the reactive iodine species IO from simultaneous active and passive DOAS observations

NASA Astrophysics Data System (ADS)

Seitz, K.; Buxmann, J.; Pöhler, D.; Sommer, T.; Tschritter, J.; O'Dowd, C.; Platt, U.

2009-10-01

We present investigations of the reactive iodine species (RIS) IO, OIO and I2 in a coastal region from a field campaign simultaneously employing active long path differential optical absorption spectroscopy (LP-DOAS) as well as passive multi-axis differential optical absorption spectroscopy (MAX-DOAS). The campaign took place at the Martin Ryan Institute (MRI) in Carna, County Galway at the Irish West Coast about 6 km south-east of the atmospheric research station Mace Head in summer 2007. In order to study the horizontal distribution of the trace gases of interest, we established two almost parallel active LP-DOAS light paths, the shorter of 1034 m length just crossing the intertidal area, whereas the longer one of 3946 m length also crossed open water during periods of low tide. In addition we operated two passive Mini-MAX-DOAS instruments with the same viewing direction. While neither OIO nor I2 could be unambiguously identified with any of the instruments, IO could be detected with active as well as passive DOAS. The IO column densities seen at both active LP-DOAS light paths are almost the same. Thus it can be concluded that coastal IO is almost exclusively located in the intertidal area, where we detected mixing ratios of up to 35±7.7 ppt (equivalent to pmol/mol). Nucleation events with particle concentrations of 106 cm-3 particles were observed each day correlating with high IO mixing ratios. Therefore we feel that our detected IO concentrations confirm the results of model studies, which state that in order to explain such particle bursts, IO mixing ratios of 50 to 100 ppt in so called "hot-spots" are required.

MAX-DOAS retrieval of aerosol extinction properties in Madrid, Spain

NASA Astrophysics Data System (ADS)

Wang, Shanshan; Cuevas, Carlos A.; Frieß, Udo; Saiz-Lopez, Alfonso

2017-04-01

We present Multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements performed in the urban environment of Madrid, Spain, from March to September 2015. The O4 absorption in the ultraviolet (UV) spectral region was used to retrieve the aerosol extinction profile using an inversion algorithm. The results show a good agreement between the hourly retrieved aerosol optical depth (AOD) and the correlative Aerosol Robotic Network (AERONET) product. Higher AODs are found in the summer season due to the more frequent occurrence of Saharan dust intrusions. The surface aerosol extinction coefficient as retrieved by the MAX-DOAS measurements was also compared to in situ PM2:5 concentrations. The level of agreement between both measurements indicates that the MAX-DOAS retrieval has the ability to characterize the extinction of aerosol particles near the surface. The retrieval algorithm was also used to study a case of severe dust intrusion on 12 May 2015. The capability of the MAX-DOAS retrieval to recognize the dust event including an elevated particle layer is investigated along with air mass back-trajectory analysis.

Low-complexity DOA estimation from short data snapshots for ULA systems using the annihilating filter technique

NASA Astrophysics Data System (ADS)

Bellili, Faouzi; Amor, Souheib Ben; Affes, Sofiène; Ghrayeb, Ali

2017-12-01

This paper addresses the problem of DOA estimation using uniform linear array (ULA) antenna configurations. We propose a new low-cost method of multiple DOA estimation from very short data snapshots. The new estimator is based on the annihilating filter (AF) technique. It is non-data-aided (NDA) and does not impinge therefore on the whole throughput of the system. The noise components are assumed temporally and spatially white across the receiving antenna elements. The transmitted signals are also temporally and spatially white across the transmitting sources. The new method is compared in performance to the Cramér-Rao lower bound (CRLB), the root-MUSIC algorithm, the deterministic maximum likelihood estimator and another Bayesian method developed precisely for the single snapshot case. Simulations show that the new estimator performs well over a wide SNR range. Prominently, the main advantage of the new AF-based method is that it succeeds in accurately estimating the DOAs from short data snapshots and even from a single snapshot outperforming by far the state-of-the-art techniques both in DOA estimation accuracy and computational cost.

DOA estimation of noncircular signals for coprime linear array via locally reduced-dimensional Capon

NASA Astrophysics Data System (ADS)

Zhai, Hui; Zhang, Xiaofei; Zheng, Wang

2018-05-01

We investigate the issue of direction of arrival (DOA) estimation of noncircular signals for coprime linear array (CLA). The noncircular property enhances the degree of freedom and improves angle estimation performance, but it leads to a more complex angle ambiguity problem. To eliminate ambiguity, we theoretically prove that the actual DOAs of noncircular signals can be uniquely estimated by finding the coincide results from the two decomposed subarrays based on the coprimeness. We propose a locally reduced-dimensional (RD) Capon algorithm for DOA estimation of noncircular signals for CLA. The RD processing is used in the proposed algorithm to avoid two dimensional (2D) spectral peak search, and coprimeness is employed to avoid the global spectral peak search. The proposed algorithm requires one-dimensional locally spectral peak search, and it has very low computational complexity. Furthermore, the proposed algorithm needs no prior knowledge of the number of sources. We also derive the Crámer-Rao bound of DOA estimation of noncircular signals in CLA. Numerical simulation results demonstrate the effectiveness and superiority of the algorithm.

DOA Estimation for Underwater Wideband Weak Targets Based on Coherent Signal Subspace and Compressed Sensing.

PubMed

Li, Jun; Lin, Qiu-Hua; Kang, Chun-Yu; Wang, Kai; Yang, Xiu-Ting

2018-03-18

Direction of arrival (DOA) estimation is the basis for underwater target localization and tracking using towed line array sonar devices. A method of DOA estimation for underwater wideband weak targets based on coherent signal subspace (CSS) processing and compressed sensing (CS) theory is proposed. Under the CSS processing framework, wideband frequency focusing is accompanied by a two-sided correlation transformation, allowing the DOA of underwater wideband targets to be estimated based on the spatial sparsity of the targets and the compressed sensing reconstruction algorithm. Through analysis and processing of simulation data and marine trial data, it is shown that this method can accomplish the DOA estimation of underwater wideband weak targets. Results also show that this method can considerably improve the spatial spectrum of weak target signals, enhancing the ability to detect them. It can solve the problems of low directional resolution and unreliable weak-target detection in traditional beamforming technology. Compared with the conventional minimum variance distortionless response beamformers (MVDR), this method has many advantages, such as higher directional resolution, wider detection range, fewer required snapshots and more accurate detection for weak targets.

Sparsity-Aware DOA Estimation Scheme for Noncircular Source in MIMO Radar

PubMed Central

Wang, Xianpeng; Wang, Wei; Li, Xin; Liu, Qi; Liu, Jing

2016-01-01

In this paper, a novel sparsity-aware direction of arrival (DOA) estimation scheme for a noncircular source is proposed in multiple-input multiple-output (MIMO) radar. In the proposed method, the reduced-dimensional transformation technique is adopted to eliminate the redundant elements. Then, exploiting the noncircularity of signals, a joint sparsity-aware scheme based on the reweighted l1 norm penalty is formulated for DOA estimation, in which the diagonal elements of the weight matrix are the coefficients of the noncircular MUSIC-like (NC MUSIC-like) spectrum. Compared to the existing l1 norm penalty-based methods, the proposed scheme provides higher angular resolution and better DOA estimation performance. Results from numerical experiments are used to show the effectiveness of our proposed method. PMID:27089345

The influence of random element displacement on DOA estimates obtained with (Khatri-Rao-)root-MUSIC.

PubMed

Inghelbrecht, Veronique; Verhaevert, Jo; van Hecke, Tanja; Rogier, Hendrik

2014-11-11

Although a wide range of direction of arrival (DOA) estimation algorithms has been described for a diverse range of array configurations, no specific stochastic analysis framework has been established to assess the probability density function of the error on DOA estimates due to random errors in the array geometry. Therefore, we propose a stochastic collocation method that relies on a generalized polynomial chaos expansion to connect the statistical distribution of random position errors to the resulting distribution of the DOA estimates. We apply this technique to the conventional root-MUSIC and the Khatri-Rao-root-MUSIC methods. According to Monte-Carlo simulations, this novel approach yields a speedup by a factor of more than 100 in terms of CPU-time for a one-dimensional case and by a factor of 56 for a two-dimensional case.

HRV-derived data similarity and distribution index based on ensemble neural network for measuring depth of anaesthesia.

PubMed

Liu, Quan; Ma, Li; Chiu, Ren-Chun; Fan, Shou-Zen; Abbod, Maysam F; Shieh, Jiann-Shing

2017-01-01

Evaluation of depth of anaesthesia (DoA) is critical in clinical surgery. Indices derived from electroencephalogram (EEG) are currently widely used to quantify DoA. However, there are known to be inaccurate under certain conditions; therefore, experienced anaesthesiologists rely on the monitoring of vital signs such as body temperature, pulse rate, respiration rate, and blood pressure to control the procedure. Because of the lack of an ideal approach for quantifying level of consciousness, studies have been conducted to develop improved methods of measuring DoA. In this study, a short-term index known as the similarity and distribution index (SDI) is proposed. The SDI is generated using heart rate variability (HRV) in the time domain and is based on observations of data distribution differences between two consecutive 32 s HRV data segments. A comparison between SDI results and expert assessments of consciousness level revealed that the SDI has strong correlation with anaesthetic depth. To optimise the effect, artificial neural network (ANN) models were constructed to fit the SDI, and ANN blind cross-validation was conducted to overcome random errors and overfitting problems. An ensemble ANN was then employed and was discovered to provide favourable DoA assessment in comparison with commonly used Bispectral Index. This study demonstrated the effectiveness of this method of DoA assessment, and the results imply that it is feasible and meaningful to use the SDI to measure DoA with the additional use of other measurement methods, if appropriate.

Retrieval of Vertical Aerosol and Trace Gas Distributions from Polarization Sensitive Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS)

NASA Astrophysics Data System (ADS)

Tirpitz, Jan-Lukas; Friess, Udo; Platt, Ulrich

2017-04-01

An accurate knowledge of the vertical distribution of trace gases and aerosols is crucial for our understanding of the chemical and dynamical processes in the lower troposphere. Their accurate determination is typically only possible by means of laborious and expensive airborne in-situ measurements but in the recent decades, numerous promising ground-based remote sensing approaches have been developed. One of them is to infer vertical distributions from "Differential Optical Absorption Spectroscopy" (DOAS) measurements. DOAS is a technique to analyze UV- and visible radiation spectra of direct or scattered sunlight, which delivers information on different atmospheric parameters, integrated over the light path from space to the instrument. An appropriate set of DOAS measurements, recorded under different viewing directions (Multi-Axis DOAS) and thus different light path geometries, provides information on the atmospheric state. The vertical profiles of aerosol properties and trace gas concentrations can be retrieved from such a set by numerical inversion techniques, incorporating radiative transfer models. The information content of measured data is rarely sufficient for a well-constrained retrieval, particularly for atmospheric layers above 1 km. We showed in first simulations that, apart from spectral properties, the polarization state of skylight is likely to provide a significant amount of additional information on the atmospheric state and thus to enhance retrieval quality. We present first simulations, expectations and ideas on how to implement and characterize a polarization sensitive Multi-Axis DOAS instrument and a corresponding profile retrieval algorithm.

Mini MAX-DOAS Measurements of Air Pollutants over China

NASA Astrophysics Data System (ADS)

Staadt, Steffen; Hao, Nan; Trautmann, Thomas

2016-08-01

This study continues the work of Clémer et al., (2010) and is aimed to improve trace gas retrievals with mini MAX-DOAS measurements in Nanjing. Based on that work, aerosol extinction vertical profiles are retrieved using the bePRO inversion algorithm developed by the Royal Belgian Institute for Space Aeronomy (BIRA- IASB). Afterwards, the tropospheric trace gas vertical profiles and vertical column densities (VCDs) are retrieved by applying the optimal estimation method to the O4 MAX-DOAS measurements. The Profiles for N O2 , S O2 , glyoxal, formaldehyde and nitrous acid are obtained with different results and different settings for the DOAS measurement. The AODs show small positive correlation against the AERONET values. For NO2, the retrieval shows reasonable concentrations in winter as opposed to summer and has small positive correlations with GOME-2 data. The SO2 VCDs are not correlated with the GOME-2 data, due to high uncertainties from MAX-DOAS and satellite retrievals, while the vertical mixing ratios (VMR) show good agreement with in-situ data (SORPES) at Nanjing. Nitrous acid shows a maximum in winter and a minimum in summer, while glyoxal has its maximum in August and September.

DOA Estimation for Underwater Wideband Weak Targets Based on Coherent Signal Subspace and Compressed Sensing

PubMed Central

2018-01-01

Direction of arrival (DOA) estimation is the basis for underwater target localization and tracking using towed line array sonar devices. A method of DOA estimation for underwater wideband weak targets based on coherent signal subspace (CSS) processing and compressed sensing (CS) theory is proposed. Under the CSS processing framework, wideband frequency focusing is accompanied by a two-sided correlation transformation, allowing the DOA of underwater wideband targets to be estimated based on the spatial sparsity of the targets and the compressed sensing reconstruction algorithm. Through analysis and processing of simulation data and marine trial data, it is shown that this method can accomplish the DOA estimation of underwater wideband weak targets. Results also show that this method can considerably improve the spatial spectrum of weak target signals, enhancing the ability to detect them. It can solve the problems of low directional resolution and unreliable weak-target detection in traditional beamforming technology. Compared with the conventional minimum variance distortionless response beamformers (MVDR), this method has many advantages, such as higher directional resolution, wider detection range, fewer required snapshots and more accurate detection for weak targets. PMID:29562642

Joint Smoothed l₀-Norm DOA Estimation Algorithm for Multiple Measurement Vectors in MIMO Radar.

PubMed

Liu, Jing; Zhou, Weidong; Juwono, Filbert H

2017-05-08

Direction-of-arrival (DOA) estimation is usually confronted with a multiple measurement vector (MMV) case. In this paper, a novel fast sparse DOA estimation algorithm, named the joint smoothed l 0 -norm algorithm, is proposed for multiple measurement vectors in multiple-input multiple-output (MIMO) radar. To eliminate the white or colored Gaussian noises, the new method first obtains a low-complexity high-order cumulants based data matrix. Then, the proposed algorithm designs a joint smoothed function tailored for the MMV case, based on which joint smoothed l 0 -norm sparse representation framework is constructed. Finally, for the MMV-based joint smoothed function, the corresponding gradient-based sparse signal reconstruction is designed, thus the DOA estimation can be achieved. The proposed method is a fast sparse representation algorithm, which can solve the MMV problem and perform well for both white and colored Gaussian noises. The proposed joint algorithm is about two orders of magnitude faster than the l 1 -norm minimization based methods, such as l 1 -SVD (singular value decomposition), RV (real-valued) l 1 -SVD and RV l 1 -SRACV (sparse representation array covariance vectors), and achieves better DOA estimation performance.

Spatial variance and assessment of nitrogen dioxide pollution in major cities of Pakistan along N5-Highway.

PubMed

Shabbir, Yasir; Khokhar, Muhammad Fahim; Shaiganfar, Reza; Wagner, Thomas

2016-05-01

This paper discusses the findings of the first car MAX-DOAS (multi-axis differential optical absorption spectroscopy) field campaign (300km long) along the National Highway-05 (N5-Highway) of Pakistan conducted on 13 and 14 November, 2012. The main objective of the field campaign was to assess the spatial distribution of tropospheric nitrogen dioxide (NO2) columns and corresponding concentrations along the N5-Highway from Islamabad to Lahore. Source identification of NO2 revealed that the concentrations were higher within major cities along the highway. The highest NO2 vertical column densities (NO2 VCDs) were found around two major cities of Rawalpindi and Lahore. This study also presents a comparison of NO2 VCDs measured by the ozone monitoring instrument (OMI) and car MAX-DOAS observations. The comparison revealed similar spatial distribution of the NO2 columns with both car MAX-DOAS and satellite observations, but the car MAX-DOAS observations show much more spatial details. Maximum NO2 VCD retrieved from car MAX-DOAS observations was up to an order of magnitude larger than the OMI observations in urban areas. Copyright © 2015. Published by Elsevier B.V.

High spatial resolution measurements of NO2 applying Topographic Target Light scattering-Differential Optical Absorption Spectroscopy (ToTaL-DOAS)

NASA Astrophysics Data System (ADS)

Frins, E.; Platt, U.; Wagner, T.

2008-06-01

Tomographic Target Light scattering - Differential Optical Absorption Spectroscopy (ToTaL-DOAS), also called Target-DOAS, is a novel experimental procedure to retrieve trace gas concentrations present in the low atmosphere. Scattered sunlight (partially or totally) reflected from natural or artificial targets of similar albedo located at different distances is analyzed to retrieve the concentration of different trace gases like NO2, SO2 and others. We report high spatial resolution measurements of NO2 mixing ratios in the city of Montevideo (Uruguay) observing three buildings as targets with a Mini-DOAS instrument. Our instrument was 146 m apart from the first building, 196 m from the second and 286 m from the third one. All three buildings are located along a main Avenue. We obtain temporal variation of NO2 mixing ratios between 30 ppb and 65 ppb (±2 ppb). Our measurements demonstrate that ToTaL-DOAS measurements can be made over very short distances. In polluted air masses, the retrieved absorption signal was found to be strong enough to allow measurements over distances in the range of several ten meters, and achieve a spatial resolution of 50 m approximately.

High spatial resolution measurements of NO2 applying Topographic Target Light scattering-Differential Optical Absorption Spectroscopy (ToTaL-DOAS)

NASA Astrophysics Data System (ADS)

Frins, E.; Platt, U.; Wagner, T.

2008-12-01

Topographic Target Light scattering - Differential Optical Absorption Spectroscopy (ToTaL-DOAS), also called Target-DOAS, is a novel experimental procedure to retrieve trace gas concentrations present in the low atmosphere. Scattered sunlight (diffuse or specular) reflected from natural or artificial targets located at different distances are analyzed to retrieve the spatial distribution of the concentration of different trace gases like NO2, SO2 and others. We report high spatial resolution measurements of NO2 mixing ratios in the city of Montevideo (Uruguay) observing three buildings as targets with a Mini-DOAS instrument. Our instrument was 146 m, 196 m, and 280 m apart from three different buildings located along a main Avenue. We obtain temporal variation of NO2 mixing ratios between 30 ppb and 65 ppb from measurements of November 2007 and mixing ratios up to 50 ppb from measurements of August and September 2008. Our measurements demonstrate that ToTaL-DOAS observations can be made over relative short distances. In polluted air masses, the retrieved absorption signal was found to be sufficiently strong to allow measurements over distances in the range of several tens of meters.

Dominant optic atrophy.

PubMed

Lenaers, Guy; Hamel, Christian; Delettre, Cécile; Amati-Bonneau, Patrizia; Procaccio, Vincent; Bonneau, Dominique; Reynier, Pascal; Milea, Dan

2012-07-09

DEFINITION OF THE DISEASE: Dominant Optic Atrophy (DOA) is a neuro-ophthalmic condition characterized by a bilateral degeneration of the optic nerves, causing insidious visual loss, typically starting during the first decade of life. The disease affects primary the retinal ganglion cells (RGC) and their axons forming the optic nerve, which transfer the visual information from the photoreceptors to the lateral geniculus in the brain. The prevalence of the disease varies from 1/10000 in Denmark due to a founder effect, to 1/30000 in the rest of the world. DOA patients usually suffer of moderate visual loss, associated with central or paracentral visual field deficits and color vision defects. The severity of the disease is highly variable, the visual acuity ranging from normal to legal blindness. The ophthalmic examination discloses on fundoscopy isolated optic disc pallor or atrophy, related to the RGC death. About 20% of DOA patients harbour extraocular multi-systemic features, including neurosensory hearing loss, or less commonly chronic progressive external ophthalmoplegia, myopathy, peripheral neuropathy, multiple sclerosis-like illness, spastic paraplegia or cataracts. Two genes (OPA1, OPA3) encoding inner mitochondrial membrane proteins and three loci (OPA4, OPA5, OPA8) are currently known for DOA. Additional loci and genes (OPA2, OPA6 and OPA7) are responsible for X-linked or recessive optic atrophy. All OPA genes yet identified encode mitochondrial proteins embedded in the inner membrane and ubiquitously expressed, as are the proteins mutated in the Leber Hereditary Optic Neuropathy. OPA1 mutations affect mitochondrial fusion, energy metabolism, control of apoptosis, calcium clearance and maintenance of mitochondrial genome integrity. OPA3 mutations only affect the energy metabolism and the control of apoptosis. Patients are usually diagnosed during their early childhood, because of bilateral, mild, otherwise unexplained visual loss related to optic discs pallor or atrophy, and typically occurring in the context of a family history of DOA. Optical Coherence Tomography further discloses non-specific thinning of retinal nerve fiber layer, but a normal morphology of the photoreceptors layers. Abnormal visual evoked potentials and pattern ERG may also reflect the dysfunction of the RGCs and their axons. Molecular diagnosis is provided by the identification of a mutation in the OPA1 gene (75% of DOA patients) or in the OPA3 gene (1% of patients). Visual loss in DOA may progress during puberty until adulthood, with very slow subsequent chronic progression in most of the cases. On the opposite, in DOA patients with associated extra-ocular features, the visual loss may be more severe over time. To date, there is no preventative or curative treatment in DOA; severely visually impaired patients may benefit from low vision aids. Genetic counseling is commonly offered and patients are advised to avoid alcohol and tobacco consumption, as well as the use of medications that may interfere with mitochondrial metabolism. Gene and pharmacological therapies for DOA are currently under investigation.

Dominant optic atrophy

PubMed Central

2012-01-01

Definition of the disease Dominant Optic Atrophy (DOA) is a neuro-ophthalmic condition characterized by a bilateral degeneration of the optic nerves, causing insidious visual loss, typically starting during the first decade of life. The disease affects primary the retinal ganglion cells (RGC) and their axons forming the optic nerve, which transfer the visual information from the photoreceptors to the lateral geniculus in the brain. Epidemiology The prevalence of the disease varies from 1/10000 in Denmark due to a founder effect, to 1/30000 in the rest of the world. Clinical description DOA patients usually suffer of moderate visual loss, associated with central or paracentral visual field deficits and color vision defects. The severity of the disease is highly variable, the visual acuity ranging from normal to legal blindness. The ophthalmic examination discloses on fundoscopy isolated optic disc pallor or atrophy, related to the RGC death. About 20% of DOA patients harbour extraocular multi-systemic features, including neurosensory hearing loss, or less commonly chronic progressive external ophthalmoplegia, myopathy, peripheral neuropathy, multiple sclerosis-like illness, spastic paraplegia or cataracts. Aetiology Two genes (OPA1, OPA3) encoding inner mitochondrial membrane proteins and three loci (OPA4, OPA5, OPA8) are currently known for DOA. Additional loci and genes (OPA2, OPA6 and OPA7) are responsible for X-linked or recessive optic atrophy. All OPA genes yet identified encode mitochondrial proteins embedded in the inner membrane and ubiquitously expressed, as are the proteins mutated in the Leber Hereditary Optic Neuropathy. OPA1 mutations affect mitochondrial fusion, energy metabolism, control of apoptosis, calcium clearance and maintenance of mitochondrial genome integrity. OPA3 mutations only affect the energy metabolism and the control of apoptosis. Diagnosis Patients are usually diagnosed during their early childhood, because of bilateral, mild, otherwise unexplained visual loss related to optic discs pallor or atrophy, and typically occurring in the context of a family history of DOA. Optical Coherence Tomography further discloses non-specific thinning of retinal nerve fiber layer, but a normal morphology of the photoreceptors layers. Abnormal visual evoked potentials and pattern ERG may also reflect the dysfunction of the RGCs and their axons. Molecular diagnosis is provided by the identification of a mutation in the OPA1 gene (75% of DOA patients) or in the OPA3 gene (1% of patients). Prognosis Visual loss in DOA may progress during puberty until adulthood, with very slow subsequent chronic progression in most of the cases. On the opposite, in DOA patients with associated extra-ocular features, the visual loss may be more severe over time. Management To date, there is no preventative or curative treatment in DOA; severely visually impaired patients may benefit from low vision aids. Genetic counseling is commonly offered and patients are advised to avoid alcohol and tobacco consumption, as well as the use of medications that may interfere with mitochondrial metabolism. Gene and pharmacological therapies for DOA are currently under investigation. PMID:22776096

Evaluating emissions of HCHO, HONO, NO2, and SO2 from point sources using portable Imaging DOAS

NASA Astrophysics Data System (ADS)

Pikelnaya, O.; Tsai, C.; Herndon, S. C.; Wood, E. C.; Fu, D.; Lefer, B. L.; Flynn, J. H.; Stutz, J.

2011-12-01

Our ability to quantitatively describe urban air pollution to a large extent depends on an accurate understanding of anthropogenic emissions. In areas with a high density of individual point sources of pollution, such as petrochemical facilities with multiple flares or regions with active commercial ship traffic, this is particularly challenging as access to facilities and ships is often restricted. Direct formaldehyde emissions from flares may play an important role for ozone chemistry, acting as an initial radical precursor and enhancing the degradation of co-emitted hydrocarbons. HONO is also recognized as an important OH source throughout the day. However, very little is known about direct HCHO and HONO emissions. Imaging Differential Optical Absorption Spectroscopy (I-DOAS), a relatively new remote sensing technique, provides an opportunity to investigate emissions from these sources from a distance, making this technique attractive for fence-line monitoring. In this presentation, we will describe I-DOAS measurements during the FLAIR campaign in the spring/summer of 2009. We performed measurements outside of various industrial facilities in the larger Houston area as well as in the Houston Ship Channel to visualize and quantify the emissions of HCHO, NO2, HONO, and SO2 from flares of petrochemical facilities and ship smoke stacks. We will present the column density images of pollutant plumes as well as fluxes from individual flares calculated from I-DOAS observations. Fluxes from individual flares and smoke stacks determined from the I-DOAS measurements vary widely in time and by the emission sources. We will also present HONO/NOx ratios in ship smoke stacks derived from the combination of I-DOAS and in-situ measurements, and discuss other trace gas ratios in plumes derived from the I-DOAS observations. Finally, we will show images of HCHO, NO2 and SO2 plumes from control burn forest fires observed in November of 2009 at Vandenberg Air Force Base, Santa Maria, CA.

Research on modified the estimates of NOx emissions combined the OMI and ground-based DOAS technique

NASA Astrophysics Data System (ADS)

Zhang, Qiong; Li*, Ang; Xie, Pinhua; Hu, Zhaokun; Wu, Fengcheng; Xu, Jin

2017-04-01

A new method to calibrate nitrogen dioxide (NO2) lifetimes and emissions from point sources using satellite measurements base on the mobile passive differential optical absorption spectroscopy (DOAS) and multi axis differential optical absorption spectroscopy (MAX-DOAS) is described. It is based on using the Exponentially-Modified Gaussian (EMG) fitting method to correct the line densities along the wind direction by fitting the mobile passive DOAS NO2 vertical column density (VCD). An effective lifetime and emission rate are then determined from the parameters of the fit. The obtained results were then compared with the results acquired by fitting OMI (Ozone Monitoring Instrument) NO2 using the above fitting method, the NOx emission rate was about 195.8mol/s, 160.6mol/s, respectively. The reason why the latter less than the former may be because the low spatial resolution of the satellite.

Development of a portable active long-path differential optical absorption spectroscopy system for volcanic gas measurements

USGS Publications Warehouse

Vita, Fabio; Kern, Christoph; Inguaggiato, Salvatore

2014-01-01

Active long-path differential optical absorption spectroscopy (LP-DOAS) has been an effective tool for measuring atmospheric trace gases for several decades. However, instruments were large, heavy and power-inefficient, making their application to remote environments extremely challenging. Recent developments in fibre-coupling telescope technology and the availability of ultraviolet light emitting diodes (UV-LEDS) have now allowed us to design and construct a lightweight, portable, low-power LP-DOAS instrument for use at remote locations and specifically for measuring degassing from active volcanic systems. The LP-DOAS was used to measure sulfur dioxide (SO2) emissions from La Fossa crater, Vulcano, Italy, where column densities of up to 1.2 × 1018 molec cm−2 (~ 500 ppmm) were detected along open paths of up to 400 m in total length. The instrument's SO2 detection limit was determined to be 2 × 1016 molec cm−2 (~ 8 ppmm), thereby making quantitative detection of even trace amounts of SO2 possible. The instrument is capable of measuring other volcanic volatile species as well. Though the spectral evaluation of the recorded data showed that chlorine monoxide (ClO) and carbon disulfide (CS2) were both below the instrument's detection limits during the experiment, the upper limits for the X / SO2 ratio (X = ClO, CS2) could be derived, and yielded 2 × 10−3 and 0.1, respectively. The robust design and versatility of the instrument make it a promising tool for monitoring of volcanic degassing and understanding processes in a range of volcanic systems.

Observations of IO hot-spots at coastal sites with the combination of a mobile CE- and LP- DOAS

NASA Astrophysics Data System (ADS)

Pöhler, D.; Horbanski, M.; Schmitt, S.; Anthofer, M.; Tschritter, J.; Platt, U.

2012-04-01

Reactive iodine species are emitted by seaweed in the intertidal zone of coastal sites during low tide. Beside their oxidation to iodine oxide (IO) and reduction of ozone, they act as precursors for particle formation and therefore have a potential impact on climate. A correlation between iodine oxide and particle formation could be observed in several field studies. However, modelling studies suggest that the so far observed mixing ratios of iodine oxide are too low to explain the observed particle formation. This may be caused by the so far applied measurement techniques which either average over a long measurement path of several km (LP-DOAS) or by immobile in-situ techniques (LIF or BB-CEAS) located typically few 10-100m of the intertidal area. Thus both techniques could not observe local "hot-spots", locations with locally elevated IO levels above the background with small spatial extend (e.g. above a source). We present a new developed Cavity Enhanced Differential Optical Absorption Spectroscopy (CE- DOAS) instrument for the direct identification of IO down to 1ppt. This technique gives the possibility to achieve long absorption light paths in a compact setup (<2.0m) and thus apply the DOAS principle to in-situ measurements. The resonator of the cavity is formed by two high reflective mirrors in the spectral window from 430-460nm. To avoid any interference of reactive iodine compounds with tubes, walls or filters, the resonator is open similar to a LP-DOAS setup. A blue LED is used as light source. The total instrument setup is relatively light (25kg) and can easily be located at different locations. Hence it is possible to setup this instrument directly over the macro algae in the intertidal area during low tide to investigate the IO spatial distribution and "hot-spots". As IO concentrations vary strongly due to different meteorological parameters, the CE-DOAS measurements are combined with LP-DOAS in the same area. Thus the combination allows deriving a spatial variability. The results from the first application during the HaloCave2010 campaign on Cape Verde will be presented. Opposite to former measurements both instruments could not observe IO at any coastal site close to the CVAO station. Recently measurements were performed along the Irish west coast (partly at the research station Mace Head during MaCloud field campaign) to investigate the IO levels emitted by macro algae. During low tide the CE-DOAS instrument was regularly set-up directly in the intertidal area above the macro algae. Results of different coastal sites will be presented in detail. Elevated IO concentrations up to several 10ppt could be observed with the CE-DOAS instrument regularly, but LP-DOAS concentrations are typically more than an order of magnitude lower. The data will be discussed according to the IO "hot-spot" theory. Even at unfavorable meteorological conditions (clouds, strong wind) the CE-DOAS instrument could regularly observe enhanced IO levels. Different coastal sites show different IO emission strength and spatial distribution. The spatial distribution of IO at different coastal sites and its impact on atmospheric chemistry will be discussed.

Enhanced B Cell Alloantigen Presentation and Its Epigenetic Dysregulation in Liver Transplant Rejection.

PubMed

Ningappa, M; Ashokkumar, C; Higgs, B W; Sun, Q; Jaffe, R; Mazariegos, G; Li, D; Weeks, D E; Subramaniam, S; Ferrell, R; Hakonarson, H; Sindhi, R

2016-02-01

T cell suppression prevents acute cellular rejection but causes life-threatening infections and malignancies. Previously, liver transplant (LTx) rejection in children was associated with the single-nucleotide polymorphism (SNP) rs9296068 upstream of the HLA-DOA gene. HLA-DOA inhibits B cell presentation of antigen, a potentially novel antirejection drug target. Using archived samples from 122 white pediatric LTx patients (including 77 described previously), we confirmed the association between rs9296068 and LTx rejection (p = 0.001, odds ratio [OR] 2.55). Next-generation sequencing revealed that the putative transcription factor (CCCTC binding factor [CTCF]) binding SNP locus rs2395304, in linkage disequilibrium with rs9296068 (D' 0.578, r(2) = 0.4), is also associated with LTx rejection (p = 0.008, OR 2.34). Furthermore, LTx rejection is associated with enhanced B cell presentation of donor antigen relative to HLA-nonidentical antigen in a novel cell-based assay and with a downregulated HLA-DOA gene in a subset of these children. In lymphoblastoid B (Raji) cells, rs2395304 coimmunoprecipitates with CTCF, and CTCF knockdown with morpholino antisense oligonucleotides enhances alloantigen presentation and downregulates the HLA-DOA gene, reproducing observations made with HLA-DOA knockdown and clinical rejection. Alloantigen presentation is suppressed by inhibitors of methylation and histone deacetylation, reproducing observations made during resolution of rejection. Enhanced donor antigen presentation by B cells and its epigenetic dysregulation via the HLA-DOA gene represent novel opportunities for surveillance and treatment of transplant rejection. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

Uniform and nonuniform V-shaped planar arrays for 2-D direction-of-arrival estimation

NASA Astrophysics Data System (ADS)

Filik, T.; Tuncer, T. E.

2009-10-01

In this paper, isotropic and directional uniform and nonuniform V-shaped arrays are considered for azimuth and elevation direction-of-arrival (DOA) angle estimation simultaneously. It is shown that the uniform isotropic V-shaped arrays (UI V arrays) have no angle coupling between the azimuth and elevation DOA. The design of the UI V arrays is investigated, and closed form expressions are presented for the parameters of the UI V arrays and nonuniform V arrays. These expressions allow one to find the isotropic V angle for different array types. The DOA performance of the UI V array is compared with the uniform circular array (UCA) for correlated signals and in case of mutual coupling between array elements. The modeling error for the sensor positions is also investigated. It is shown that V array and circular array have similar robustness for the position errors while the performance of UI V array is better than the UCA for correlated source signals and when there is mutual coupling. Nonuniform V-shaped isotropic arrays are investigated which allow good DOA performance with limited number of sensors. Furthermore, a new design method for the directional V-shaped arrays is proposed. This method is based on the Cramer-Rao Bound for joint estimation where the angle coupling effect between the azimuth and elevation DOA angles is taken into account. The design method finds an optimum angle between the linear subarrays of the V array. The proposed method can be used to obtain directional arrays with significantly better DOA performance.

EEG artifacts reduction by multivariate empirical mode decomposition and multiscale entropy for monitoring depth of anaesthesia during surgery.

PubMed

Liu, Quan; Chen, Yi-Feng; Fan, Shou-Zen; Abbod, Maysam F; Shieh, Jiann-Shing

2017-08-01

Electroencephalography (EEG) has been widely utilized to measure the depth of anaesthesia (DOA) during operation. However, the EEG signals are usually contaminated by artifacts which have a consequence on the measured DOA accuracy. In this study, an effective and useful filtering algorithm based on multivariate empirical mode decomposition and multiscale entropy (MSE) is proposed to measure DOA. Mean entropy of MSE is used as an index to find artifacts-free intrinsic mode functions. The effect of different levels of artifacts on the performances of the proposed filtering is analysed using simulated data. Furthermore, 21 patients' EEG signals are collected and analysed using sample entropy to calculate the complexity for monitoring DOA. The correlation coefficients of entropy and bispectral index (BIS) results show 0.14 ± 0.30 and 0.63 ± 0.09 before and after filtering, respectively. Artificial neural network (ANN) model is used for range mapping in order to correlate the measurements with BIS. The ANN method results show strong correlation coefficient (0.75 ± 0.08). The results in this paper verify that entropy values and BIS have a strong correlation for the purpose of DOA monitoring and the proposed filtering method can effectively filter artifacts from EEG signals. The proposed method performs better than the commonly used wavelet denoising method. This study provides a fully adaptive and automated filter for EEG to measure DOA more accuracy and thus reduce risk related to maintenance of anaesthetic agents.

Airborne MAX-DOAS Measurements Over California: Testing the NASA OMI Tropospheric NO2 Product

NASA Technical Reports Server (NTRS)

Oetjen, Hilke; Baidar, Sunil; Krotkov, Nickolay A.; Lamsal, Lok N.; Lechner, Michael; Volkamer, Rainer

2013-01-01

Airborne Multi-AXis Differential Optical Absorption Spectroscopy (AMAX-DOAS) measurements of NO2 tropospheric vertical columns were performed over California for two months in summer 2010. The observations are compared to the NASA Ozone Monitoring Instrument (OMI) tropospheric vertical columns (data product v2.1) in two ways: (1) Median data were compared for the whole time period for selected boxes, and the agreement was found to be fair (R = 0.97, slope = 1.4 +/- 0.1, N= 10). (2) A comparison was performed on the mean of coincident AMAX-DOAS measurements within the area of the corresponding OMI pixels with the tropospheric NASA OMI NO2 assigned to that pixel. The effects of different data filters were assessed. Excellent agreement and a strong correlation (R = 0.85, slope = 1.05 +/- 0.09, N= 56) was found for (2) when the data were filtered to eliminate large pixels near the edge of the OMI orbit, the cloud radiance fraction was<50%, the OMI overpass occurred within 2 h of the AMAX-DOAS measurements, the flight altitude was>2 km, and a representative sample of the footprint was taken by the AMAX-DOAS instrument. The AMAX-DOAS and OMI data sets both show a reduction of NO2 tropospheric columns on weekends by 38 +/- 24% and 33 +/- 11%, respectively. The assumptions in the tropospheric satellite air mass factor simulations were tested using independent measurements of surface albedo, aerosol extinction, and NO2 profiles for Los Angeles for July 2010 indicating an uncertainty of 12%.

15 CFR 700.15 - Extension of priority ratings.

Code of Federal Regulations, 2011 CFR

2011-01-01

... receipt of a DO-A3 rated order for a navigation system and needs to purchase semiconductors for its manufacture, that person must use a DO-A3 rated order to obtain the needed semiconductors. (b) The priority...

Results of 2008-2009 Pennsylvania wood destroying insect survey

Treesearch

Sven-Erik Spichiger

2011-01-01

The Pennsylvania Department of Agriculture (DOA) participates in a variety of insect surveys each year to detect new and potentially invasive species affecting plants in Pennsylvania. Surveys are carried out by seasonal survey crews, permanent DOA staff, and cooperating agencies.

Direction of arrival estimation using blind separation of sources

NASA Astrophysics Data System (ADS)

Hirari, Mehrez; Hayakawa, Masashi

1999-05-01

The estimation of direction of arrival (DOA) and polarization of an incident electromagnetic (EM) wave is of great importance in many applications. In this paper we propose a new approach for the estimation of DOA for polarized EM waves using blind separation of sources. In this approach we use a vector sensor, a sensor whose output is a complete set of the EM field components of the irradiating wave, and we reconstruct the waveforms of all the original signals that is, all the EM components of the sources' fields. From the waveform of each source we calculate its amplitude and phase and consequently calculate its DOA and polarization using the field analysis method. The separation of sources is conducted iteratively using a recurrent Hopfield-like single-layer neural network. The simulation results for two sources have been investigated. We have considered coherent and incoherent sources and also the case of varying DOAs vis-ā-vis the sensor and a varying polarization. These are cases seldom treated by other approaches even though they exist in real-world applications. With the proposed method we have obtained almost on-time tracking for the DOA and polarization of any incident sources with a significant reduction of both memory and computation costs.

Parameter Estimation of Multiple Frequency-Hopping Signals with Two Sensors

PubMed Central

Pan, Jin; Ma, Boyuan

2018-01-01

This paper essentially focuses on parameter estimation of multiple wideband emitting sources with time-varying frequencies, such as two-dimensional (2-D) direction of arrival (DOA) and signal sorting, with a low-cost circular synthetic array (CSA) consisting of only two rotating sensors. Our basic idea is to decompose the received data, which is a superimposition of phase measurements from multiple sources into separated groups and separately estimate the DOA associated with each source. Motivated by joint parameter estimation, we propose to adopt the expectation maximization (EM) algorithm in this paper; our method involves two steps, namely, the expectation-step (E-step) and the maximization (M-step). In the E-step, the correspondence of each signal with its emitting source is found. Then, in the M-step, the maximum-likelihood (ML) estimates of the DOA parameters are obtained. These two steps are iteratively and alternatively executed to jointly determine the DOAs and sort multiple signals. Closed-form DOA estimation formulae are developed by ML estimation based on phase data, which also realize an optimal estimation. Directional ambiguity is also addressed by another ML estimation method based on received complex responses. The Cramer-Rao lower bound is derived for understanding the estimation accuracy and performance comparison. The verification of the proposed method is demonstrated with simulations. PMID:29617323

Extended reactance domain algorithms for DoA estimation onto an ESPAR antennas

NASA Astrophysics Data System (ADS)

Harabi, F.; Akkar, S.; Gharsallah, A.

2016-07-01

Based on an extended reactance domain (RD) covariance matrix, this article proposes new alternatives for directions of arrival (DoAs) estimation of narrowband sources through an electronically steerable parasitic array radiator (ESPAR) antennas. Because of the centro symmetry of the classic ESPAR antennas, an unitary transformation is applied to the collected data that allow an important reduction in both computational cost and processing time and, also, an enhancement of the resolution capabilities of the proposed algorithms. Moreover, this article proposes a new approach for eigenvalues estimation through only some linear operations. The developed DoAs estimation algorithms based on this new approach has illustrated a good behaviour with less calculation cost and processing time as compared to other schemes based on the classic eigenvalues approach. The conducted simulations demonstrate that high-precision and high-resolution DoAs estimation can be reached especially in very closely sources situation and low sources power as compared to the RD-MUSIC algorithm and the RD-PM algorithm. The asymptotic behaviours of the proposed DoAs estimators are analysed in various scenarios and compared with the Cramer-Rao bound (CRB). The conducted simulations testify the high-resolution of the developed algorithms and prove the efficiently of the proposed approach.

Profiles of Urine Drug Test in Clinical Pain Patients vs Pain Research Study Subjects.

PubMed

Lee, Cheng-ting; Vo, Trang T; Cohen, Abigail S; Ahmed, Shihab; Zhang, Yi; Mao, Jianren; Chen, Lucy

2016-04-01

To examine similarities and differences in urine drug test (UDT) results in clinical pain patients and pain subjects participating in pain research studies. An observational study with retrospective chart review and data analysis. We analyzed 1,874 UDT results obtained from 1) clinical pain patients (Clinical Group; n = 1,529) and 2) pain subjects consented to participate in pain research studies (Research Group; n = 345). Since several medications such as opioids used in pain management are drugs of abuse (DOA) and can result in a positive UDT, we specifically identified those cases of positive UDT due to nonprescribed DOA and designated these cases as positive UDT with DOA (PUD). We found that 1) there was a higher rate of PUD in clinical pain patients (41.3%) than in pain research study subjects (14.8%); 2) although subjects in the Research Group were informed ahead of time that UDT will be conducted as a screening test, a substantial number (14.8%) of pain research study subjects still showed PUD; 3) there were different types of DOA between clinical pain patients (cannabinoids as the top DOA) and research study subjects (cocaine as the top DOA); and 4) a common factor associated with PUD was opioid therapy in both Clinical Group and Research Group. These results support previous findings that PUD is a common finding in clinical pain patients, particularly in those prescribed opioid therapy, and we suggest that UDT be used as routine screening testing in pain research studies. © 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The effect of cloud screening on MAX-DOAS aerosol retrievals.

NASA Astrophysics Data System (ADS)

Gielen, Clio; Van Roozendael, Michel; Hendrik, Francois; Fayt, Caroline; Hermans, Christian; Pinardi, Gaia; De Backer, Hugo; De Bock, Veerle; Laffineur, Quentin; Vlemmix, Tim

2014-05-01

In recent years, ground-based multi-axis differential absorption spectroscopy (MAX-DOAS) has shown to be ideally suited for the retrieval of tropospheric trace gases and deriving information on the aerosol properties. These measurements are invaluable to our understanding of the physics and chemistry of the atmospheric system, and the impact on the Earth's climate. Unfortunately, MAX-DOAS measurements are often performed under strong non-clear-sky conditions, causing strong data quality degradation and uncertainties on the retrievals. Here we present the result of our cloud-screening method, using the colour index (CI), on aerosol retrievals from MAX-DOAS measurements (AOD and vertical profiles). We focus on two large data sets, from the Brussels and Beijing area. Using the CI we define 3 different sky conditions: bad (=full thick cloud cover/extreme aerosols), mediocre (=thin clouds/aerosols) and good (=clear sky). We also flag the presence of broken/scattered clouds. We further compare our cloud-screening method with results from cloud-cover fractions derived from thermic infrared measurements. In general, our method shows good results to qualify the sky and cloud conditions of MAX-DOAS measurements, without the need for other external cloud-detection systems. Removing data under bad-sky and broken-cloud conditions results in a strongly improved agreement, in both correlation and slope, between the MAX-DOAS aerosol retrievals and data from other instruments (e.g. AERONET, Brewer). With the improved AOD retrievals, the seasonal and diurnal variations of the aerosol content and vertical distribution at both sites can be investigated in further detail. By combining with additional information derived by other instruments (Brewer, lidar, ...) operated at the stations, we will further study the observed aerosol characteristics, and their influence on and by meteorological conditions such as clouds and/or the boundary layer height.

Generation of a rabbit single-chain fragment variable (scFv) antibody for specific detection of Bradyrhizobium sp. DOA9 in both free-living and bacteroid forms

PubMed Central

Srila, Witsanu; Yuttavanichakul, Watcharin; Teamtisong, Kamonluck; Teaumroong, Neung; Boonkerd, Nantakorn; Tittabutr, Panlada

2017-01-01

A simple and reliable method for the detection of specific nitrogen-fixing bacteria in both free-living and bacteroid forms is essential for the development and application of biofertilizer. Traditionally, a polyclonal antibody generated from an immunized rabbit was used for detection. However, the disadvantages of using a polyclonal antibody include limited supply and cross-reactivity to related bacterial strains. This is the first report on the application of phage display technology for the generation of a rabbit recombinant monoclonal antibody for specific detection and monitoring of nitrogen-fixing bacteria in both free-living form and in plant nodules. Bradyrhizobium sp. DOA9, a broad host range soil bacteria, originally isolated from the root nodules of Aeschynomene americana in Thailand was used as a model in this study. A recombinant single-chain fragment variable (scFv) antibody library was constructed from the spleen of a rabbit immunized with DOA9. After three rounds of biopanning, one specific phage-displayed scFv antibody, designated bDOA9rb8, was identified. Specific binding of this antibody was confirmed by phage enzyme-linked immunosorbent assay (phage ELISA). The phage antibody could bind specifically to DOA9 in both free-living cells (pure culture) and bacteroids inside plant nodules. In addition to phage ELISA, specific and robust immunofluorescence staining of both free-living and bacteroid forms could also be observed by confocal-immunofluorescence imaging, without cross-reactivity with other tested bradyrhizobial strains. Moreover, specific binding of free scFv to DOA9 was also demonstrated by ELISA. This recombinant antibody can also be used for the study of the molecular mechanism of plant–microbe interactions in the future. PMID:28654662

Generation of a rabbit single-chain fragment variable (scFv) antibody for specific detection of Bradyrhizobium sp. DOA9 in both free-living and bacteroid forms.

PubMed

Vu, Nguyen Xuan; Pruksametanan, Natcha; Srila, Witsanu; Yuttavanichakul, Watcharin; Teamtisong, Kamonluck; Teaumroong, Neung; Boonkerd, Nantakorn; Tittabutr, Panlada; Yamabhai, Montarop

2017-01-01

A simple and reliable method for the detection of specific nitrogen-fixing bacteria in both free-living and bacteroid forms is essential for the development and application of biofertilizer. Traditionally, a polyclonal antibody generated from an immunized rabbit was used for detection. However, the disadvantages of using a polyclonal antibody include limited supply and cross-reactivity to related bacterial strains. This is the first report on the application of phage display technology for the generation of a rabbit recombinant monoclonal antibody for specific detection and monitoring of nitrogen-fixing bacteria in both free-living form and in plant nodules. Bradyrhizobium sp. DOA9, a broad host range soil bacteria, originally isolated from the root nodules of Aeschynomene americana in Thailand was used as a model in this study. A recombinant single-chain fragment variable (scFv) antibody library was constructed from the spleen of a rabbit immunized with DOA9. After three rounds of biopanning, one specific phage-displayed scFv antibody, designated bDOA9rb8, was identified. Specific binding of this antibody was confirmed by phage enzyme-linked immunosorbent assay (phage ELISA). The phage antibody could bind specifically to DOA9 in both free-living cells (pure culture) and bacteroids inside plant nodules. In addition to phage ELISA, specific and robust immunofluorescence staining of both free-living and bacteroid forms could also be observed by confocal-immunofluorescence imaging, without cross-reactivity with other tested bradyrhizobial strains. Moreover, specific binding of free scFv to DOA9 was also demonstrated by ELISA. This recombinant antibody can also be used for the study of the molecular mechanism of plant-microbe interactions in the future.

Open-path Emission Factors Derived from DOAS and FTIR Measurements in the Mexico City Metropolitan Area

NASA Astrophysics Data System (ADS)

Flores, E.; Grutter, M.; Galle, B.; Mellqvist, J.; Samuelsson, J.; Knighton, B.; Jobson, B. T.; Volkamer, R.; Molina, L. T.; Molina, M. J.

2004-12-01

Mobile sources are responsible for about 50% of VOC (volatile organic compounds) and about 70% of NOx emissions in the Mexico City Metropolitan Area (MCMA). A novel approach has been developed to derive emission factors for mobile sources that are representative of the overall vehicle fleet, using collocated open-path Differential Optical Absorption Spectroscopy (DOAS) and Fourier Transform Infrared (FTIR) spectroscopic measurements. Measurements were recorded at two sites within the MCMA: (1) research-grade DOAS and FTIR systems were operated at the Mexican National Research and Training Center (CENICA) in Iztapalapa, (2) a research grade FTIR was operated at La Merced. In addition, point-sampling with a proton transfer reaction mass spectrometer (PTR-MS) was performed on the same location and the calibration standards for the PTR-MS and the DOAS instruments were cross-calibrated. The DOAS measured speciated aromatic hydrocarbons, including benzene, toluene, m-xylene, p-xylene, ethylbenzene (and mono-substituted alkylbenzenes), benzaldehyde, phenol, and p-cresol. The DOAS detection of aromatic hydrocarbons in the UV/vis spectral range between 250 to 310 nm suffers from the interference of molecular oxygen, and a novel approach is being presented that enables measurement of absolute concentrations of the above species. Further, HONO, NO2, SO2 and HCHO were measured at longer wavelengths. In combination with FTIR measurements of CO, CO2, NO, HCHO, ethylene, ethene, and total alkane, average emission factors for NOx, SO2 and numerous hydrocarbons were derived and scaled with fuel sales data to estimate total emissions of the vehicle fleet in the MCMA. The advantages and limitations of this low-cost emission inventory for mobile sources are decsribed.

How well can the observed Arctic sea ice summer retreat and winter advance be represented in the NCEP Climate Forecast System version 2?

NASA Astrophysics Data System (ADS)

Collow, Thomas W.; Wang, Wanqiu; Kumar, Arun; Zhang, Jinlun

2017-09-01

The capability of a numerical model to simulate the statistical characteristics of the summer sea ice date of retreat (DOR) and the winter date of advance (DOA) is investigated using sea ice concentration output from the Climate Forecast System Version 2 model (CFSv2). Two model configurations are tested, the operational setting (CFSv2CFSR) which uses initial data from the Climate Forecast System Reanalysis, and a modified version (CFSv2PIOMp) which ingests sea ice thickness initialization data from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) and includes physics modifications for a more realistic representation of heat fluxes at the sea ice top and bottom. First, a method to define DOR and DOA is presented. Then, DOR and DOA are determined from the model simulations and observational sea ice concentration from the National Aeronautics and Space Administration (NASA). Means, trends, and detrended standard deviations of DOR and DOA are compared, along with DOR/DOA rates in the Arctic Ocean. It is found that the statistics are generally similar between the model and observations, although some regional biases exist. In addition, regions of new ice retreat in recent years are represented well in CFSv2PIOMp over the Arctic Ocean, in terms of both spatial extent and timing. Overall, CFSv2PIOMp shows a reduction in error throughout the Arctic. Based on results, it is concluded that the model produces a reasonable representation of the climatology and variability statistics of DOR and DOA in most regions. This assessment serves as a prerequisite for future predictability experiments.

Single snapshot DOA estimation

NASA Astrophysics Data System (ADS)

Häcker, P.; Yang, B.

2010-10-01

In array signal processing, direction of arrival (DOA) estimation has been studied for decades. Many algorithms have been proposed and their performance has been studied thoroughly. Yet, most of these works are focused on the asymptotic case of a large number of snapshots. In automotive radar applications like driver assistance systems, however, only a small number of snapshots of the radar sensor array or, in the worst case, a single snapshot is available for DOA estimation. In this paper, we investigate and compare different DOA estimators with respect to their single snapshot performance. The main focus is on the estimation accuracy and the angular resolution in multi-target scenarios including difficult situations like correlated targets and large target power differences. We will show that some algorithms lose their ability to resolve targets or do not work properly at all. Other sophisticated algorithms do not show a superior performance as expected. It turns out that the deterministic maximum likelihood estimator is a good choice under these hard conditions.

MAX-DOAS measurements of aerosol, HCHO, and NO2 over Los Angeles from an elevated mountaintop site

NASA Astrophysics Data System (ADS)

Cheung, Ross

MAX-DOAS measurements of aerosol, HCHO, and NO2 over Los Angeles from an elevated mountaintop site. By. Ross Cheung. Doctor of Philosophy in Atmospheric and Oceanic Sciences. University of California, Los Angeles, 2016. Professor Jochen Stutz, Chair. Differential Optical Absorption Spectroscopy (DOAS) has become a popular technique for measuring atmospheric trace gases using UV/Vis narrow-band absorption features along a light path through the atmosphere. The UCLA Multi-Axis DOAS instrument (MAX-DOAS) is a ground-based spectrometer currently located at Mt. Wilson, California (1700 meters above sea level) that measures solar scattered light at various viewing elevation angles. Since May of 2010, it has been taking regular measurements of atmospheric pollutants in the boundary layer of the atmosphere in and above the Los Angeles Basin. This thesis presents the experimental setup and spectral retrievals, as well as results of our observations of measurements of NO2 and HCHO from Mt. Wilson. Radiative transfer modeling efforts of the deployment at Mt. Wilson will be presented, as well as our efforts to model and account for the effects of clouds and aerosols on MAX-DOAS measurements. Because of the unique challenges presented by aerosols in the ultraviolet and visible light region in a polluted urban boundary layer, new techniques were developed to account for and quantify these effects. Observations of path-integrated NO2 and HCHO, some of the primary precursors to ozone formation in the lower troposphere, as well as aerosol extinctions using the UCLA MAX-DOAS will be presented, and the advantages of a mountaintop measurement strategy will be discussed in light of the amount of vertical information that can be retrieved from this approach. The techniques developed to improve the optimal estimation of vertical aerosol extinction profiles and trace gas concentration profiles will be discussed. Finally, an application of these observations uses the ratio of HCHO/NO2 to study the dependency of ozone formation on nitrogen oxides and VOCs will be presented.

Comparison of MAX-DOAS profiling algorithms during CINDI-2 - Part 1: aerosols

NASA Astrophysics Data System (ADS)

Friess, Udo; Hendrick, Francois; Tirpitz, Jan-Lukas; Apituley, Arnoud; van Roozendael, Michel; Kreher, Karin; Richter, Andreas; Wagner, Thomas

2017-04-01

The second Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI-2) took place at the Cabauw Experimental Site for Atmospheric Research (CESAR; Utrecht area, The Netherlands) from 25 August until 7 October 2016. CINDI-2 was aiming at assessing the consistency of MAX-DOAS slant column density measurements of tropospheric species (NO2, HCHO, O3, and O4) relevant for the validation of future ESA atmospheric Sentinel missions, through coordinated operation of a large number of DOAS and MAXDOAS instruments from all over the world. An important objective of the campaign was to study the relationship between remote-sensing column and profile measurements of the above species and collocated reference ancillary observations. For this purpose, the CINDI-2 Profiling Task Team (CPTT) was created, involving 22 groups performing aerosol and trace gas vertical profile inversion using dedicated MAX-DOAS profiling algorithms, as well as the teams responsible for ancillary profile and surface concentration measurements (NO2 analysers, NO2 sondes, NO2 and Raman LIDARs, CAPS, Long-Path DOAS, sun photometer, nephelometer, etc). The main purpose of the CPTT is to assess the consistency of the different profiling tools for retrieving aerosol extinction and trace gas vertical profiles through comparison exercises using commonly defined settings and to validate the retrievals with correlative observations. In this presentation, we give an overview of the MAX-DOAS vertical profile comparison results, focusing on the retrieval of aerosol extinction profiles, with the trace gas retrievals being presented in a companion abstract led by F. Hendrick. The performance of the different algorithms is investigated with respect to the variable visibility and cloud conditions encountered during the campaign. The consistency between optimal-estimation-based and parameterized profiling tools is also evaluated for these different conditions, together with the level of agreement with available ancillary aerosol observations, including sun photometer, nephelometer and LIDAR. This comparison study will be put in the perspective of the development of a centralized MAX-DOAS processing system within the framework of the ESA Fiducial Reference Measurements (FRM) project.

Comparison of MAX-DOAS profiling algorithms during CINDI-2 - Part 2: trace gases

NASA Astrophysics Data System (ADS)

Hendrick, Francois; Friess, Udo; Tirpitz, Lukas; Apituley, Arnoud; Van Roozendael, Michel; Kreher, Karin; Richter, Andreas; Wagner, Thomas

2017-04-01

The second Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI-2) took place at the Cabauw Experimental Site for Atmospheric Research (CESAR; Utrecht area, The Netherlands) from 25 August until 7 October 2016. CINDI-2 was aiming at assessing the consistency of MAX-DOAS slant column density measurements of tropospheric species (NO2, HCHO, O3, and O4) relevant for the validation of future ESA atmospheric Sentinel missions, through coordinated operation of a large number of DOAS and MAXDOAS instruments from all over the world. An important objective of the campaign was to study the relationship between remote-sensing column and profile measurements of the above species and collocated reference ancillary observations. For this purpose, the CINDI-2 Profiling Task Team (CPTT) was created, involving 22 groups performing aerosol and trace gas vertical profile inversion using dedicated MAX-DOAS profiling algorithms, as well as the teams responsible for ancillary profile and surface concentration measurements (NO2 analysers, NO2 sondes, NO2 and Raman LIDARs, CAPS, Long-Path DOAS, sunphotometer, nephelometer, etc). The main purpose of the CPTT is to assess the consistency of the different profiling tools for retrieving aerosol extinction and trace gas vertical profiles through comparison exercises using commonly defined settings and to validate the retrievals with correlative observations. In this presentation, we give an overview of the MAX-DOAS vertical profile comparison results, focusing on NO2 and HCHO, the aerosol retrievals being presented in a companion abstract led by U. Frieß. The performance of the different algorithms is investigated with respect to the various sky and weather conditions and aerosol loadings encountered during the campaign. The consistency between optimal-estimation-based and parameterized profiling tools is also evaluated for these different conditions, together with the level of agreement with available NO2 and HCHO ancillary observations. This comparison study will be put in the perspective of the development of a centralized MAX-DOAS processing system within the framework of the ESA Fiducial Reference Measurements (FRM) project.

Tracking a convoy of multiple targets using acoustic sensor data

NASA Astrophysics Data System (ADS)

Damarla, T. R.

2003-08-01

In this paper we present an algorithm to track a convoy of several targets in a scene using acoustic sensor array data. The tracking algorithm is based on template of the direction of arrival (DOA) angles for the leading target. Often the first target is the closest target to the sensor array and hence the loudest with good signal to noise ratio. Several steps were used to generate a template of the DOA angle for the leading target, namely, (a) the angle at the present instant should be close to the angle at the previous instant and (b) the angle at the present instant should be within error bounds of the predicted value based on the previous values. Once the template of the DOA angles of the leading target is developed, it is used to predict the DOA angle tracks of the remaining targets. In order to generate the tracks for the remaining targets, a track is established if the angles correspond to the initial track values of the first target. Second the time delay between the first track and the remaining tracks are estimated at the highest correlation points between the first track and the remaining tracks. As the vehicles move at different speeds the tracks either compress or expand depending on whether a target is moving fast or slow compared to the first target. The expansion and compression ratios are estimated and used to estimate the predicted DOA angle values of the remaining targets. Based on these predicted DOA angles of the remaining targets the DOA angles obtained from the MVDR or Incoherent MUSIC will be appropriately assigned to proper tracks. Several other rules were developed to avoid mixing the tracks. The algorithm is tested on data collected at Aberdeen Proving Ground with a convoy of 3, 4 and 5 vehicles. Some of the vehicles are tracked and some are wheeled vehicles. The tracking algorithm results are found to be good. The results will be presented at the conference and in the paper.

Current State of Military Hybrid Vehicle Development

DTIC Science & Technology

2011-01-01

programme were: • EP-50 parallel hybrid light armoured vehicle (LAV-III) and a refuse hauler • advanced hybrid electric drive (AHED) 8 × 8, 20 ton...Qingnian, W., Liang, C. and Weihua, W. (2003) ‘Energy management strategy and parametric design for hybrid electric military vehicle’, SAE Paper No...herein do not necessarily state or reflect those of the US Government or the DoA, and shall not be used for advertising or product endorsement purposes. 2 Unclassified. Distribution Statement A. Approved for public release.

Joint Estimation of Time-Frequency Signature and DOA Based on STFD for Multicomponent Chirp Signals

PubMed Central

Zhao, Ziyue; Liu, Congfeng

2014-01-01

In the study of the joint estimation of time-frequency signature and direction of arrival (DOA) for multicomponent chirp signals, an estimation method based on spatial time-frequency distributions (STFDs) is proposed in this paper. Firstly, array signal model for multicomponent chirp signals is presented and then array processing is applied in time-frequency analysis to mitigate cross-terms. According to the results of the array processing, Hough transform is performed and the estimation of time-frequency signature is obtained. Subsequently, subspace method for DOA estimation based on STFD matrix is achieved. Simulation results demonstrate the validity of the proposed method. PMID:27382610

Joint Estimation of Time-Frequency Signature and DOA Based on STFD for Multicomponent Chirp Signals.

PubMed

Zhao, Ziyue; Liu, Congfeng

2014-01-01

In the study of the joint estimation of time-frequency signature and direction of arrival (DOA) for multicomponent chirp signals, an estimation method based on spatial time-frequency distributions (STFDs) is proposed in this paper. Firstly, array signal model for multicomponent chirp signals is presented and then array processing is applied in time-frequency analysis to mitigate cross-terms. According to the results of the array processing, Hough transform is performed and the estimation of time-frequency signature is obtained. Subsequently, subspace method for DOA estimation based on STFD matrix is achieved. Simulation results demonstrate the validity of the proposed method.

Retrieval columns of SO2 in industrial chimneys using DOAS passive in traverse

NASA Astrophysics Data System (ADS)

Galicia Mejía, Rubén; de la Rosa Vázquez, José Manuel; Sosa Iglesias, Gustavo

2011-10-01

The optical Differential Optical Absorption Spectroscopy (DOAS) is a technique to measure pollutant emissions like SO2, from point sources and total fluxes in the atmosphere. Passive DOAS systems use sunlight like source. Measurements with such systems can be made in situ and in real time. The goal of this work is to report the implementation of hardware and software of a portable system to evaluate the pollutants emitted in the atmosphere by industrial chimneys. We show SO2 measurements obtained around PEMEX refinerys in Tula Hidalgo that enables the identification of their pollution degree with the knowledge of speed wind.

DOA Finding with Support Vector Regression Based Forward-Backward Linear Prediction.

PubMed

Pan, Jingjing; Wang, Yide; Le Bastard, Cédric; Wang, Tianzhen

2017-05-27

Direction-of-arrival (DOA) estimation has drawn considerable attention in array signal processing, particularly with coherent signals and a limited number of snapshots. Forward-backward linear prediction (FBLP) is able to directly deal with coherent signals. Support vector regression (SVR) is robust with small samples. This paper proposes the combination of the advantages of FBLP and SVR in the estimation of DOAs of coherent incoming signals with low snapshots. The performance of the proposed method is validated with numerical simulations in coherent scenarios, in terms of different angle separations, numbers of snapshots, and signal-to-noise ratios (SNRs). Simulation results show the effectiveness of the proposed method.

Wide-band array signal processing via spectral smoothing

NASA Technical Reports Server (NTRS)

Xu, Guanghan; Kailath, Thomas

1989-01-01

A novel algorithm for the estimation of direction-of-arrivals (DOA) of multiple wide-band sources via spectral smoothing is presented. The proposed algorithm does not require an initial DOA estimate or a specific signal model. The advantages of replacing the MUSIC search with an ESPRIT search are discussed.

The Leaderless Social Movement Organization: Unstoppable Power or Last-Ditch Effort

DTIC Science & Technology

2010-12-01

Front Press Office Environmental Facts - GMOs ,” http://www.elfpressoffice.org/doa.html. 86 Leader and Probst, “The Earth Liberation Front and...Front Press Office Environmental Facts - GMOs .” Accessed November 22, 2009. http://www.elfpressoffice.org/doa.html. ———. “Earth Liberation Front

15 CFR 700.15 - Extension of priority ratings.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) BUREAU OF INDUSTRY AND SECURITY, DEPARTMENT OF COMMERCE NATIONAL SECURITY INDUSTRIAL BASE REGULATIONS... receipt of a DO-A3 rated order for a navigation system and needs to purchase semiconductors for its manufacture, that person must use a DO-A3 rated order to obtain the needed semiconductors. (b) The priority...

Nullspace MUSIC and Improved Radio Frequency Emitter Geolocation from a Mobile Antenna Array

NASA Astrophysics Data System (ADS)

Kintz, Andrew L.

This work advances state-of-the-art Radio Frequency (RF) emitter geolocation from an airborne or spaceborne antenna array. With an antenna array, geolocation is based on Direction of Arrival (DOA) estimation algorithms such as MUSIC. The MUSIC algorithm applies to arbitrary arrays of polarization sensitive antennas and yields high resolution. However, MUSIC fails to obtain its theoretical resolution for simultaneous, closely spaced, co-frequency signals. We propose the novel Nullspace MUSIC algorithm, which outperforms MUSIC and its existing modifications while maintaining MUSIC(apostrophe)s fundamental orthogonality test. Nullspace MUSIC applies a divide-and-conquer approach and estimates a single DOA at a time. Additionally, an antenna array on an aircraft cannot be perfectly calibrated. RF waves are blocked, reflected, and scattered in a time-varying fashion by the platform around the antenna array. Consequently, full-wave electromagnetics simulations or demanding measurements of the entire platform cannot eliminate the mismatch between the true, in-situ antenna patterns and the antenna patterns that are available for DOA estimation (the antenna array manifold). Platform-induced manifold mismatch severely degrades MUSIC(apostrophe)s resolution and accuracy. We show that Nullspace MUSIC improves DOA accuracy for well separated signals that are incident on an airborne antenna array. Conventionally, geolocation from a mobile platform draws Lines of Bearing (LOB) from the antenna array along the DOAs to find the locations where the DOAs intersect with the ground. However, averaging the LOBs in the global coordinate system yields large errors due to geometric dilution of precision. Since averaging positions fails, a single emitter is typically located by finding the position on the ground that yields the Minimum Apparent Angular Error (MAAE) for the DOA estimates over a flight. We extend the MAAE approach to cluster LOBs from multiple emitters. MAAE clustering geolocates multiple simultaneous and co-frequency emitters in spite of highly erratic DOA estimates. We also mitigate manifold mismatch by applying the Direct Mapping Method (DMM). DMM averages DOA spectra on the earth(apostrophe)s surface and estimates the emitter locations directly from the composite spectrum. In the example results presented, our goal is to geolocate four diversely polarized emitters with a seven-element antenna array. This is too challenging for MAAE and DMM. We fuse Nullspace MUSIC and DMM into the novel Nullspace DMM algorithm and demonstrate that Nullspace DMM locates all emitters. Finally, we apply the proposed geolocation algorithms to real-world experimental data. A six-element antenna array and Data Collection System (DCS) were installed on a small aircraft. The DCS recorded signals from four live transmitters during a three-hour flight over Columbus, Ohio. The four emitters were geolocated from various segments of the flight. As expected, individual DOA estimates were erratic and widespread due to the airplane(apostrophe)s perturbations of the measured array manifold. MAAE and DMM locate at most three of the four emitters. On the other hand, Nullspace DMM yields unambiguous estimates for every emitter in every flight segment. The successful experimental trials show that Nullspace DMM could significantly enhance airborne emitter geolocation in missions such as RF spectrum enforcement, locating unknown transmitters for defense, and search and rescue operations.

Mechanisms underlying brain monitoring during anesthesia: limitations, possible improvements, and perspectives

PubMed Central

2016-01-01

Currently, anesthesiologists use clinical parameters to directly measure the depth of anesthesia (DoA). This clinical standard of monitoring is often combined with brain monitoring for better assessment of the hypnotic component of anesthesia. Brain monitoring devices provide indices allowing for an immediate assessment of the impact of anesthetics on consciousness. However, questions remain regarding the mechanisms underpinning these indices of hypnosis. By briefly describing current knowledge of the brain's electrical activity during general anesthesia, as well as the operating principles of DoA monitors, the aim of this work is to simplify our understanding of the mathematical processes that allow for translation of complex patterns of brain electrical activity into dimensionless indices. This is a challenging task because mathematical concepts appear remote from clinical practice. Moreover, most DoA algorithms are proprietary algorithms and the difficulty of exploring the inner workings of mathematical models represents an obstacle to accurate simplification. The limitations of current DoA monitors — and the possibility for improvement — as well as perspectives on brain monitoring derived from recent research on corticocortical connectivity and communication are also discussed. PMID:27066200

P-glycoprotein interactions of novel psychoactive substances - stimulation of ATP consumption and transport across Caco-2 monolayers.

PubMed

Meyer, Markus R; Wagmann, Lea; Schneider-Daum, Nicole; Loretz, Brigitta; de Souza Carvalho, Cristiane; Lehr, Claus-Michael; Maurer, Hans H

2015-04-01

In contrast to drugs for therapeutic use, there are only few data available concerning interactions between P-glycoprotein (P-gp) and drugs of abuse (DOA). In this work, interactions between structurally diverse DOA and P-gp were investigated using different strategies. First, the effect on the P-gp ATPase activity was studied by monitoring of ATP consumption after addition to recombinant, human P-gp. Second, DOA showing an increased ATP consumption were further characterized regarding their transport across filter grown Caco-2- monolayers. Analyses were performed by luminescence and liquid chromatography-mass spectrometry, respectively. Among the nine DOA initially screened, benzedrone, diclofensine, glaucine, JWH-200, MDBC, WIN-55,212-2 showed an increase of ATP consumption in the ATPase stimulation assay. In Caco-2 transport studies, Glaucine, JWH-200, mitragynine, WIN-55,212-2 could moreover be identified as non-transported substrates, but inhibitors of P-gp activity. Thus, drug-drug or drug-food interactions should be very likely for these compounds. Copyright © 2015 Elsevier Inc. All rights reserved.

Genetic algorithm-based improved DOA estimation using fourth-order cumulants

NASA Astrophysics Data System (ADS)

Ahmed, Ammar; Tufail, Muhammad

2017-05-01

Genetic algorithm (GA)-based direction of arrival (DOA) estimation is proposed using fourth-order cumulants (FOC) and ESPRIT principle which results in Multiple Invariance Cumulant ESPRIT algorithm. In the existing FOC ESPRIT formulations, only one invariance is utilised to estimate DOAs. The unused multiple invariances (MIs) must be exploited simultaneously in order to improve the estimation accuracy. In this paper, a fitness function based on a carefully designed cumulant matrix is developed which incorporates MIs present in the sensor array. Better DOA estimation can be achieved by minimising this fitness function. Moreover, the effectiveness of Newton's method as well as GA for this optimisation problem has been illustrated. Simulation results show that the proposed algorithm provides improved estimation accuracy compared to existing algorithms, especially in the case of low SNR, less number of snapshots, closely spaced sources and high signal and noise correlation. Moreover, it is observed that the optimisation using Newton's method is more likely to converge to false local optima resulting in erroneous results. However, GA-based optimisation has been found attractive due to its global optimisation capability.

The IMD innate immunity pathway of Drosophila influences somatic sex determination via regulation of the Doa locus.

PubMed

Zhao, Yunpo; Cocco, Claudia; Domenichini, Severine; Samson, Marie-Laure; Rabinow, Leonard

2015-11-15

The IMD pathway induces the innate immune response to infection by gram-negative bacteria. We demonstrate strong female-to-male sex transformations in double mutants of the IMD pathway in combination with Doa alleles. Doa encodes a protein kinase playing a central role in somatic sex determination through its regulation of alternative splicing of dsx transcripts. Transcripts encoding two specific Doa isoforms are reduced in Rel null mutant females, supporting our genetic observations. A role for the IMD pathway in somatic sex determination is further supported by the induction of female-to-male sex transformations by Dredd mutations in sensitized genetic backgrounds. In contrast, mutations in either dorsal or Dif, the two other NF-κB paralogues of Drosophila, display no effects on sex determination, demonstrating the specificity of IMD signaling. Our results reveal a novel role for the innate immune IMD signaling pathway in the regulation of somatic sex determination in addition to its role in response to microbial infection, demonstrating its effects on alternative splicing through induction of a crucial protein kinase. Copyright © 2015 Elsevier Inc. All rights reserved.

Optical Remote Sensing Measurements of Air Pollution in Mexico City During MCMA- 2006

NASA Astrophysics Data System (ADS)

Galle, B.; Mellqvist, J.; Johansson, M.; Rivera, C.; Samuelsson, J.; Zhang, Y.

2007-05-01

During March 2006 the Optical Remote sensing group at Chalmers University of Technology participated in the MCMA-2006 field campaign in Mexico City, performing measurements of air pollution using a set of different optical remote sensing instruments. This poster gives an overview of the techniques applied and results obtained. The techniques applied were: Solar Occultation FTIR and UV spectroscopy from fixed locations throughout the MCMA area, yielding total columns of CO, CH2O, SO2 and NO2. Long Path FTIR measurements from site T0 located in the north part of central Mexico City. With this instrument line-averaged concentration measurements of CO and CO2 was obtained in parallel with DOAS measurements performed by other partners. MAX-DOAS measurements from site T0, yielding total column and spatial distributions of SO2 and NO2. Mobile DOAS scattered Sunlight measurements of total columns of SO2 and NO2 in and around the MCMA area. Mobile and stationary DOAS measurements in the vicinity of Tula and Popocatépetl in order to quantify emissions from industry and volcano.

Doxorubicin-loaded oligonucleotide conjugated gold nanoparticles: A promising in vivo drug delivery system for colorectal cancer therapy.

PubMed

Lee, Chang-Seuk; Kim, Hyungjoo; Yu, Joonhee; Yu, Su Hwan; Ban, Seona; Oh, Seunghyun; Jeong, Dongjun; Im, Jungkyun; Baek, Moo Jun; Kim, Tae Hyun

2017-12-15

In this study, we propose doxorubicin (DOX) loaded oligonucleotides (ONTs) attached to gold nanoparticles (AuNPs) as a drug delivery system for cancer chemotherapy. DOX is one of the representative cancer chemotherapy agents and is widely used by many researchers as a chemotherapy agent in the drug delivery system. Due to the advantages of AuNPs such as simple steps in synthesis, high surface-area-to-volume ratio, and biocompatibility, we utilized AuNPs as drug delivery vehicle. AuNPs were synthesized by chemical reduction to be 13 nm diameter. The G-C rich oligonucleotides were used both for drug loading sites and AuNPs capping agents. 80% of DOX in solution could be bound to ONTs on AuNPs to became DOX-loaded AuNPs coated with ONTs (Doxorubicin-Oligomer-AuNP, DOA), and about 28% of loaded DOX was released from the as-prepared DOA. Confocal microscopy observation showed that DOA was well transported into cells, and finally the DOX was released into the cell nucleus. The drug's efficacies such as in vitro cytotoxicity and in vivo tumor growth inhibition were demonstrated with SW480 colon cancer cell line and a xenograft mouse model. MTT assay was performed to see the cytotoxicity effect on SW480 cells treated with DOA for 24 h, and the cell viability was determined to be 41.77% (p < 0.001). When DOA was administered regularly to a tumor bearing mouse, the tumor growth inhibition degree was examined by measuring the tumor size. The treatment-control (T/C) ratio was found to be 0.69. Thus, our results suggest the use of DOAs as promising drug delivery systems for colorectal cancer therapy. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

MAX-DOAS observations and their application to the validation of satellite and model data in Wuxi, China

NASA Astrophysics Data System (ADS)

Wang, Y.; Wagner, T.; Xie, P.; Theys, N.; De Smedt, I.; Koukouli, M.; Stavrakou, T.; Beirle, S.; Li, A.

2015-12-01

Thomas Wagner1, Pinhua Xie2, Nicolas Theys3, Isabelle De Smedt3, MariLiza Koukouli4, Trissevgeni Stavrakou3, Steffen Beirle1, Ang Li2,1) Satellite group, Max Planck institute for Chemistry, Mainz, Germany2) Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, China 3) BIRA-IASB, Brussels, Belgium 4) Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, Greece From 2011 to 2014 a MAX-DOAS instrument developed by the Anhui Institute of Optics and Fine Mechanics institute is operated in Wuxi, China, which is locatd about 100 km west of Shanghai. We determine the tropospheric vertical column densities (VCDs), near surface concentrations and vertical profiles of aerosols, NO2, SO2, HCHO from the MAX-DOAS observations using the optimal estimation profile retrieval algorithm (refered to as "PriAM"). We verified the results by comparing them with results from independent techniques, such as sun photometer (AERONET), a visibility meter and a long-path DOAS instrument. We acquire the cloud and aerosol conditions using a cloud classification scheme based on the MAX-DOAS observations (Wang et al., AMTD, 2015). Based on the obtained results, we characterize the effect of the clouds on the trace gas and aerosol profiles retrieved from MAX-DOAS. Then we characterize the diurnal, annual and weekly variations of the trace gases and aerosols and validate the tropospheric trace gas VCDs derived from the Ozone Monitoring instrument (OMI) on the Aura satellite platform as well as the model results from the IMAGES, CHIMERE and Lotos-Euros models and analyse the agreement depending on the cloud and aerosol conditions. Besides the direct comparison with the satellite data, we also use the trace gas and aerosol profiles derived from MAX-DOAS to recalculate the air mass factor (AMF) for the satellite observations and to evaluate the corresponding improvement of the satellite VCDs. In some periods with strong aerosol pollution, we evaluate the effect of the aerosols on the satellite cloud retrievals and the corresponding errors of the tropospheric AMF of the trace gases. Here should be noted that aerosol effects on the AMF is not yet considered in the published satellite products, which can cause appreciable errors of the tropospheric VCD of satellite products around polluted regions.

15 CFR 700.11 - Priority ratings.

Code of Federal Regulations, 2010 CFR

2010-01-01

... DO-A1 or DX-A1 priority rating. A contract for a radar set will contain a DO-A7 or DX-A7 priority... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Priority ratings. 700.11 Section 700... DEFENSE PRIORITIES AND ALLOCATIONS SYSTEM Industrial Priorities § 700.11 Priority ratings. (a) Levels of...

Repeated ice water tests and electrical perception threshold determination to detect a neurologic cause of detrusor overactivity.

PubMed

van Meel, Tom David; de Wachter, Stefan; Wyndaele, Jean-Jacques

2007-10-01

To explore the added value of a repeated ice water test (IWT) and electrical perception threshold (EPT) measurement in the search for a neurologic cause of idiopathic detrusor overactivity (DOA). The IWT, if originally negative, was repeated up to three times, and EPT measurements were done in 63 patients with neurologic DOA, 117 patients with idiopathic DOA without outflow obstruction, and 30 women with stress urinary incontinence without DOA. Although the IWT was positive in 46% of the neurologic patients if used once, this percentage became 86% when the IWT was repeated. In nonneurologic patients, one IWT was positive in only 7% and when repeated, the positive test rate increased to 24%. IWT, even repeated, remained negative in the women with stress urinary incontinence. The EPTs were not significantly different between the neurologic and nonneurologic patients with a positive IWT, except after the third instillation. In those with negative IWTs, the EPTs were significantly different between the neurologic and nonneurologic patients, independent of the number of IWTs done. If the EPTs were compared within each group between those with positive and negative IWTs, the difference was not significant at the first IWT. However, the difference became statistically significant after two IWTs for the nonneurologic group and after three IWTs for both groups. Our results have shown that repeating the IWT will increase its positivity. Combining the IWT and EPT will reinforce the results of both tests and can indicate more clearly the possibility of an unsuspected neurologic pathologic finding in patients with idiopathic DOA.

Theoretical and experimental study of DOA estimation using AML algorithm for an isotropic and non-isotropic 3D array

NASA Astrophysics Data System (ADS)

Asgari, Shadnaz; Ali, Andreas M.; Collier, Travis C.; Yao, Yuan; Hudson, Ralph E.; Yao, Kung; Taylor, Charles E.

2007-09-01

The focus of most direction-of-arrival (DOA) estimation problems has been based mainly on a two-dimensional (2D) scenario where we only need to estimate the azimuth angle. But in various practical situations we have to deal with a three-dimensional scenario. The importance of being able to estimate both azimuth and elevation angles with high accuracy and low complexity is of interest. We present the theoretical and the practical issues of DOA estimation using the Approximate-Maximum-Likelihood (AML) algorithm in a 3D scenario. We show that the performance of the proposed 3D AML algorithm converges to the Cramer-Rao Bound. We use the concept of an isotropic array to reduce the complexity of the proposed algorithm by advocating a decoupled 3D version. We also explore a modified version of the decoupled 3D AML algorithm which can be used for DOA estimation with non-isotropic arrays. Various numerical results are presented. We use two acoustic arrays each consisting of 8 microphones to do some field measurements. The processing of the measured data from the acoustic arrays for different azimuth and elevation angles confirms the effectiveness of the proposed methods.

Wireless Sensor Array Network DoA Estimation from Compressed Array Data via Joint Sparse Representation.

PubMed

Yu, Kai; Yin, Ming; Luo, Ji-An; Wang, Yingguan; Bao, Ming; Hu, Yu-Hen; Wang, Zhi

2016-05-23

A compressive sensing joint sparse representation direction of arrival estimation (CSJSR-DoA) approach is proposed for wireless sensor array networks (WSAN). By exploiting the joint spatial and spectral correlations of acoustic sensor array data, the CSJSR-DoA approach provides reliable DoA estimation using randomly-sampled acoustic sensor data. Since random sampling is performed at remote sensor arrays, less data need to be transmitted over lossy wireless channels to the fusion center (FC), and the expensive source coding operation at sensor nodes can be avoided. To investigate the spatial sparsity, an upper bound of the coherence of incoming sensor signals is derived assuming a linear sensor array configuration. This bound provides a theoretical constraint on the angular separation of acoustic sources to ensure the spatial sparsity of the received acoustic sensor array signals. The Cram e ´ r-Rao bound of the CSJSR-DoA estimator that quantifies the theoretical DoA estimation performance is also derived. The potential performance of the CSJSR-DoA approach is validated using both simulations and field experiments on a prototype WSAN platform. Compared to existing compressive sensing-based DoA estimation methods, the CSJSR-DoA approach shows significant performance improvement.

Directions of arrival estimation with planar antenna arrays in the presence of mutual coupling

NASA Astrophysics Data System (ADS)

Akkar, Salem; Harabi, Ferid; Gharsallah, Ali

2013-06-01

Directions of arrival (DoAs) estimation of multiple sources using an antenna array is a challenging topic in wireless communication. The DoAs estimation accuracy depends not only on the selected technique and algorithm, but also on the geometrical configuration of the antenna array used during the estimation. In this article the robustness of common planar antenna arrays against unaccounted mutual coupling is examined and their DoAs estimation capabilities are compared and analysed through computer simulations using the well-known MUltiple SIgnal Classification (MUSIC) algorithm. Our analysis is based on an electromagnetic concept to calculate an approximation of the impedance matrices that define the mutual coupling matrix (MCM). Furthermore, a CRB analysis is presented and used as an asymptotic performance benchmark of the studied antenna arrays. The impact of the studied antenna arrays geometry on the MCM structure is also investigated. Simulation results show that the UCCA has more robustness against unaccounted mutual coupling and performs better results than both UCA and URA geometries. The performed simulations confirm also that, although the UCCA achieves better performance under complicated scenarios, the URA shows better asymptotic (CRB) behaviour which promises more accuracy on DoAs estimation.

Opo lidar sounding of trace atmospheric gases in the 3 - 4 μm spectral range

NASA Astrophysics Data System (ADS)

Romanovskii, Oleg A.; Sadovnikov, Sergey A.; Kharchenko, Olga V.; Yakovlev, Semen V.

2018-04-01

The applicability of a KTA crystal-based laser system with optical parametric oscillators (OPO) generation to lidar sounding of the atmosphere in the spectral range 3-4 μm is studied in this work. A technique developed for lidar sounding of trace atmospheric gases (TAG) is based on differential absorption lidar (DIAL) method and differential optical absorption spectroscopy (DOAS). The DIAL-DOAS technique is tested to estimate its efficiency for lidar sounding of atmospheric trace gases. The numerical simulation performed shows that a KTA-based OPO laser is a promising source of radiation for remote DIAL-DOAS sounding of the TAGs under study along surface tropospheric paths. A possibility of using a PD38-03-PR photodiode for the DIAL gas analysis of the atmosphere is shown.

Bromine Explosions In Smog Chamber Experiments: A comparison of Cavity-Enhanced (CE) and White-cell DOAS

NASA Astrophysics Data System (ADS)

Buxmann, J.; Hoch, D. J.; Sihler, H.; Pöhler, D.; Platt, U.; Bleicher, S.; Balzer, N.; Zetzsch, C.

2011-12-01

Reactive halogen species (RHS), such as Cl, Br or BrO, can significantly influence chemical processes in the troposphere, including the destruction of ozone, change in the chemical balance of hydrogen radicals (OH, HO2), increased deposition of toxic compounds (like mercury) with potential consequences for the global climate. Previous studies have shown that salt lakes can be significant sources for gaseous RHS. Environmental conditions such as salt composition, relative humidity (RH), pH, and temperature (T) can strongly influence reactive bromine levels, but are difficult to quantify in the field. Therefore, we conducted laboratory experiments by exposing NaCl salt containing 0.33% (by weight) NaBr to simulated sunlight in a Teflon smog-chamber under various conditions of RH and ozone concentrations. BrO levels were observed by a Differential-Optical-Absorption-Spectrometer (DOAS) in combination with a multi-reflection cell (White-cell). The concentrations of OH- and Cl- radicals were quantified by the radical clock method. We present the first direct observation of BrO from the "Bromine Explosion" (auto catalytic release of reactive bromine from salt surfaces - key to ozone destruction) in the laboratory above a simulated salt pan. The maximum BrO mixing ratio of 6419±71 ppt at 60% RH was observed to be one order of magnitude higher than at 37% RH and 2% RH. The release of RHS from the salt pan is possibly controlled by the thickness of the quasi liquid layer, covering the reactive surface of the halide crystals, as the layer thickness strongly depends on RH. Furthermore, a new cavity enhanced DOAS (CE-DOAS) instrument was designed and successfully used in chamber experiments. For the first time, such an instrument uses a spectral interval in the UV - wavelength range (325-365 nm) to identify BrO. We show a comparison of the CE-DOAS and White-cell DOAS instrument in a series of experiments, where e.g. a peak BrO mixing ratio up to 380 ppt within the first minutes was observed by both instruments (relative humidity 29%, 20°C, initial [O3]=300ppb). The detection limits with a time resolution of less than five minutes per measurement were found for BrO at 25 ppt, for HCHO at 5.5 ppb, for O3 at 55 ppb for the CE-DOAS. The White-cell has a higher detection limit at a better minimal time resolution of one minute per measurement with BrO at 40 ppt, for HCHO at 10 ppb and for O3 at 300 ppb, respectively. The new BrO-CE DOAS instruments with high spatial resolution also looks very promising for future field measurement campaigns aimed at a better understanding of atmospheric processes, such as halogen activation.

Development of a cloud-screening method for MAX-DOAS measurements

NASA Astrophysics Data System (ADS)

Gielen, Clio; Van Roozendael, Michel; Hendrik, Francois; Fayt, Caroline; Hermans, Christian; Pinardi, Gaia; Vlemmix, Tim

2013-04-01

In recent years, ground-based multi-axis differential absorption spectroscopy (MAX-DOAS) has shown to be ideally suited for the retrieval of tropospheric trace gases and deriving information on the aerosol properties. These measurements are invaluable to our understanding of the physics and chemistry of the atmospheric system, and the impact on the Earth's climate. Unfortunately, MAX-DOAS measurements are often performed under (partially) cloudy conditions, causing data quality degradation and higher uncertainties on the retrievals. A high aerosol load and/or a strong cloud cover can introduce additional photon absorption or multiple scattering. The first effect strongly impacts the retrieved differential slant columns (DSCDs) of the trace gases, leading to an underestimation of the atmospheric column density. Multiple scattering, on the other hand, becomes important for low clouds with a high optical depth, and cause a strong increase in the retrieved trace gas DSCDs. The presence of thin clouds can furthermore introduce a degeneracy in the retrieved aerosol optical depth, since they will have similar effect on the MAX-DOAS measurements. In this case, only information on the trace gas DSCDs can be successfully retrieved. If the cloud cover consists of broken or scattered clouds, the MAX-DOAS method becomes very unstable, since the different elevation angels will probe regions of the sky with strongly deviating properties. Here we present a method to qualify the sky and cloud conditions, using the colour index and O4 DSCDs, as derived from the MAX-DOAS measurements. The colour index is defined as the ratio of the intensities at the short- and long-wavelength part of the visible spectral range, typically at 400 nm and 670 nm. For increasing optical thickness due to clouds or aerosols, the colour index values decrease and values for different elevation angles converge. In the case of broken clouds, the colour index shows a strong and rapid temporal variation, which is easily detectable. Additional information is derived from the O4 DSCD measurements, since they are quite sensitive to the change of the light paths due to scattering at different altitudes. For example, thick clouds at low altitude show a very strong increase in the DSCD values due to scattering, combined with a low colour index value due to the intensity screening. In general, our method shows promising results to qualify the sky and cloud conditions of MAX- DOAS measurements, without the need for other external cloud-detection systems such as Brewer instruments or pyrheliometers.

Potential of remote sensing of cirrus optical thickness by airborne spectral radiance measurements at different sideward viewing angles

NASA Astrophysics Data System (ADS)

Wolf, Kevin; Ehrlich, André; Hüneke, Tilman; Pfeilsticker, Klaus; Werner, Frank; Wirth, Martin; Wendisch, Manfred

2017-03-01

Spectral radiance measurements collected in nadir and sideward viewing directions by two airborne passive solar remote sensing instruments, the Spectral Modular Airborne Radiation measurement sysTem (SMART) and the Differential Optical Absorption Spectrometer (mini-DOAS), are used to compare the remote sensing results of cirrus optical thickness τ. The comparison is based on a sensitivity study using radiative transfer simulations (RTS) and on data obtained during three airborne field campaigns: the North Atlantic Rainfall VALidation (NARVAL) mission, the Mid-Latitude Cirrus Experiment (ML-CIRRUS) and the Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems (ACRIDICON) campaign. Radiative transfer simulations are used to quantify the sensitivity of measured upward radiance I with respect to τ, ice crystal effective radius reff, viewing angle of the sensor θV, spectral surface albedo α, and ice crystal shape. From the calculations it is concluded that sideward viewing measurements are generally better suited than radiance data from the nadir direction to retrieve τ of optically thin cirrus, especially at wavelengths larger than λ = 900 nm. Using sideward instead of nadir-directed spectral radiance measurements significantly improves the sensitivity and accuracy in retrieving τ, in particular for optically thin cirrus of τ ≤ 2. The comparison of retrievals of τ based on nadir and sideward viewing radiance measurements from SMART, mini-DOAS and independent estimates of τ from an additional active remote sensing instrument, the Water Vapor Lidar Experiment in Space (WALES), shows general agreement within the range of measurement uncertainties. For the selected example a mean τ of 0.54 ± 0.2 is derived from SMART, and 0.49 ± 0.2 by mini-DOAS nadir channels, while WALES obtained a mean value of τ = 0.32 ± 0.02 at 532 nm wavelength, respectively. The mean of τ derived from the sideward viewing mini-DOAS channels is 0.26 ± 0.2. For the few simultaneous measurements, the mini-DOAS sideward channel measurements systematically underestimate (-17.6 %) the nadir observations from SMART and mini-DOAS. The agreement between mini-DOAS sideward viewing channels and WALES is better, showing the advantage of using sideward viewing measurements for cloud remote sensing for τ ≤ 1. Therefore, we suggest sideward viewing measurements for retrievals of τ of thin cirrus because of the significantly enhanced capability of sideward viewing compared to nadir measurements.

Far-field DOA estimation and source localization for different scenarios in a distributed sensor network

NASA Astrophysics Data System (ADS)

Asgari, Shadnaz

Recent developments in the integrated circuits and wireless communications not only open up many possibilities but also introduce challenging issues for the collaborative processing of signals for source localization and beamforming in an energy-constrained distributed sensor network. In signal processing, various sensor array processing algorithms and concepts have been adopted, but must be further tailored to match the communication and computational constraints. Sometimes the constraints are such that none of the existing algorithms would be an efficient option for the defined problem and as the result; the necessity of developing a new algorithm becomes undeniable. In this dissertation, we present the theoretical and the practical issues of Direction-Of-Arrival (DOA) estimation and source localization using the Approximate-Maximum-Likelihood (AML) algorithm for different scenarios. We first investigate a robust algorithm design for coherent source DOA estimation in a limited reverberant environment. Then, we provide a least-square (LS) solution for source localization based on our newly proposed virtual array model. In another scenario, we consider the determination of the location of a disturbance source which emits both wideband acoustic and seismic signals. We devise an enhanced AML algorithm to process the data collected at the acoustic sensors. For processing the seismic signals, two distinct algorithms are investigated to determine the DOAs. Then, we consider a basic algorithm for fusion of the results yielded by the acoustic and seismic arrays. We also investigate the theoretical and practical issues of DOA estimation in a three-dimensional (3D) scenario. We show that the performance of the proposed 3D AML algorithm converges to the Cramer-Rao Bound. We use the concept of an isotropic array to reduce the complexity of the proposed algorithm by advocating a decoupled 3D version. We also explore a modified version of the decoupled 3D AML algorithm which can be used for DOA estimation with non-isotropic arrays. In this dissertation, for each scenario, efficient numerical implementations of the corresponding AML algorithm are derived and applied into a real-time sensor network testbed. Extensive simulations as well as experimental results are presented to verify the effectiveness of the proposed algorithms.

Car MAX-DOAS measurements of the tropospheric Formaldehyde (HCHO) column around Bucharest (Romania) and in the Rhein-Main area (Germany)

NASA Astrophysics Data System (ADS)

Donner, Sebastian; Shaiganfar, Reza; Riffel, Katharina; Dörner, Steffen; Lampel, Johannes; Remmers, Julia; Wagner, Thomas

2016-04-01

The DOAS (differential optical absorption spectroscopy)-method analyses the absorptions of atmospheric trace gases in spectra of scattered sun light. It is an excellent way to determine the concentrations of different trace gases (e.g. NO2, SO2, HCHO…) simultaneously. MAX (Multi-AXis)-DOAS measurements observe scattered sun light under different elevation angles. From such measurements tropospheric vertical column densities (VCDs) or even vertical profiles of the measured trace gases and aerosols can be determined. We performed mobile MAX-DOAS measurements using two instruments on the roof of a car in summer 2015 in Romania during the AROMAT2 campaign and in the Winter/Spring 2016 in the Rhein-Main area (Germany). The latter is one of the densest populated areas in Germany. One instrument is a commercial Mini-MAX-DOAS instrument from the Hoffmann company, the other a self-built instrument using an AVANTES spectrometer with better optical characteristics. The instruments were looking in two different directions (one forward and one backward). Mobile MAX-DOAS measurements cover a quite large area in a short period of time. This enables to map existing gradients of concentrations of tropospheric trace gases, e.g. NO2 and HCHO. The results of those measurements then can be used to validate satellite measurements or can be compared to model results. In this study we focus on formaldehyde (HCHO). In small amounts it is emitted directly by industries and other anthropogenic and biogenic activities. Large amounts are mostly secondary produced. As it is an intermediate product of basic oxidation cycles of other hydrocarbons its concentrations are determined by the abundances of other hydrocarbons. Therefore it can be used as an indicator for volatile organic compounds (VOCs). Furthermore HCHO plays an important role in photochemical smog chemistry and tropospheric O3 chemistry. In this work we present the measurement setup and preliminary HCHO results of the AROMAT2 campaign and first results of the measurements in the Rhein-Main area. We characterize the amounts, spatial gradients and identify potential emission sources of HCHO.

Observations of the vertical distributions of summertime atmospheric pollutants and the corresponding ozone production in Shanghai, China

NASA Astrophysics Data System (ADS)

Xing, Chengzhi; Liu, Cheng; Wang, Shanshan; Chan, Ka Lok; Gao, Yang; Huang, Xin; Su, Wenjing; Zhang, Chengxin; Dong, Yunsheng; Fan, Guangqiang; Zhang, Tianshu; Chen, Zhenyi; Hu, Qihou; Su, Hang; Xie, Zhouqing; Liu, Jianguo

2017-12-01

Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) and lidar measurements were performed in Shanghai, China, during May 2016 to investigate the vertical distribution of summertime atmospheric pollutants. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) and formaldehyde (HCHO) concentrations were retrieved from MAX-DOAS measurements using the Heidelberg Profile (HEIPRO) algorithm, while vertical distribution of ozone (O3) was obtained from an ozone lidar. Sensitivity study of the MAX-DOAS aerosol profile retrieval shows that the a priori aerosol profile shape has significant influences on the aerosol profile retrieval. Aerosol profiles retrieved from MAX-DOAS measurements with Gaussian a priori profile demonstrate the best agreements with simultaneous lidar measurements and vehicle-based tethered-balloon observations among all a priori aerosol profiles. Tropospheric NO2 vertical column densities (VCDs) measured with MAX-DOAS show a good agreement with OMI satellite observations with a Pearson correlation coefficient (R) of 0.95. In addition, measurements of the O3 vertical distribution indicate that the ozone productions do not only occur at surface level but also at higher altitudes (about 1.1 km). Planetary boundary layer (PBL) height and horizontal and vertical wind field information were integrated to discuss the ozone formation at upper altitudes. The results reveal that enhanced ozone concentrations at ground level and upper altitudes are not directly related to horizontal and vertical transportation. Similar patterns of O3 and HCHO vertical distributions were observed during this campaign, which implies that the ozone productions near the surface and at higher altitudes are mainly influenced by the abundance of volatile organic compounds (VOCs) in the lower troposphere.

Wearable Sensor Localization Considering Mixed Distributed Sources in Health Monitoring Systems

PubMed Central

Wan, Liangtian; Han, Guangjie; Wang, Hao; Shu, Lei; Feng, Nanxing; Peng, Bao

2016-01-01

In health monitoring systems, the base station (BS) and the wearable sensors communicate with each other to construct a virtual multiple input and multiple output (VMIMO) system. In real applications, the signal that the BS received is a distributed source because of the scattering, reflection, diffraction and refraction in the propagation path. In this paper, a 2D direction-of-arrival (DOA) estimation algorithm for incoherently-distributed (ID) and coherently-distributed (CD) sources is proposed based on multiple VMIMO systems. ID and CD sources are separated through the second-order blind identification (SOBI) algorithm. The traditional estimating signal parameters via the rotational invariance technique (ESPRIT)-based algorithm is valid only for one-dimensional (1D) DOA estimation for the ID source. By constructing the signal subspace, two rotational invariant relationships are constructed. Then, we extend the ESPRIT to estimate 2D DOAs for ID sources. For DOA estimation of CD sources, two rational invariance relationships are constructed based on the application of generalized steering vectors (GSVs). Then, the ESPRIT-based algorithm is used for estimating the eigenvalues of two rational invariance matrices, which contain the angular parameters. The expressions of azimuth and elevation for ID and CD sources have closed forms, which means that the spectrum peak searching is avoided. Therefore, compared to the traditional 2D DOA estimation algorithms, the proposed algorithm imposes significantly low computational complexity. The intersecting point of two rays, which come from two different directions measured by two uniform rectangle arrays (URA), can be regarded as the location of the biosensor (wearable sensor). Three BSs adopting the smart antenna (SA) technique cooperate with each other to locate the wearable sensors using the angulation positioning method. Simulation results demonstrate the effectiveness of the proposed algorithm. PMID:26985896

Wearable Sensor Localization Considering Mixed Distributed Sources in Health Monitoring Systems.

PubMed

Wan, Liangtian; Han, Guangjie; Wang, Hao; Shu, Lei; Feng, Nanxing; Peng, Bao

2016-03-12

In health monitoring systems, the base station (BS) and the wearable sensors communicate with each other to construct a virtual multiple input and multiple output (VMIMO) system. In real applications, the signal that the BS received is a distributed source because of the scattering, reflection, diffraction and refraction in the propagation path. In this paper, a 2D direction-of-arrival (DOA) estimation algorithm for incoherently-distributed (ID) and coherently-distributed (CD) sources is proposed based on multiple VMIMO systems. ID and CD sources are separated through the second-order blind identification (SOBI) algorithm. The traditional estimating signal parameters via the rotational invariance technique (ESPRIT)-based algorithm is valid only for one-dimensional (1D) DOA estimation for the ID source. By constructing the signal subspace, two rotational invariant relationships are constructed. Then, we extend the ESPRIT to estimate 2D DOAs for ID sources. For DOA estimation of CD sources, two rational invariance relationships are constructed based on the application of generalized steering vectors (GSVs). Then, the ESPRIT-based algorithm is used for estimating the eigenvalues of two rational invariance matrices, which contain the angular parameters. The expressions of azimuth and elevation for ID and CD sources have closed forms, which means that the spectrum peak searching is avoided. Therefore, compared to the traditional 2D DOA estimation algorithms, the proposed algorithm imposes significantly low computational complexity. The intersecting point of two rays, which come from two different directions measured by two uniform rectangle arrays (URA), can be regarded as the location of the biosensor (wearable sensor). Three BSs adopting the smart antenna (SA) technique cooperate with each other to locate the wearable sensors using the angulation positioning method. Simulation results demonstrate the effectiveness of the proposed algorithm.

Blind source separation and localization using microphone arrays

NASA Astrophysics Data System (ADS)

Sun, Longji

The blind source separation and localization problem for audio signals is studied using microphone arrays. Pure delay mixtures of source signals typically encountered in outdoor environments are considered. Our proposed approach utilizes the subspace methods, including multiple signal classification (MUSIC) and estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithms, to estimate the directions of arrival (DOAs) of the sources from the collected mixtures. Since audio signals are generally considered broadband, the DOA estimates at frequencies with the large sum of squared amplitude values are combined to obtain the final DOA estimates. Using the estimated DOAs, the corresponding mixing and demixing matrices are computed, and the source signals are recovered using the inverse short time Fourier transform. Subspace methods take advantage of the spatial covariance matrix of the collected mixtures to achieve robustness to noise. While the subspace methods have been studied for localizing radio frequency signals, audio signals have their special properties. For instance, they are nonstationary, naturally broadband and analog. All of these make the separation and localization for the audio signals more challenging. Moreover, our algorithm is essentially equivalent to the beamforming technique, which suppresses the signals in unwanted directions and only recovers the signals in the estimated DOAs. Several crucial issues related to our algorithm and their solutions have been discussed, including source number estimation, spatial aliasing, artifact filtering, different ways of mixture generation, and source coordinate estimation using multiple arrays. Additionally, comprehensive simulations and experiments have been conducted to examine various aspects of the algorithm. Unlike the existing blind source separation and localization methods, which are generally time consuming, our algorithm needs signal mixtures of only a short duration and therefore supports real-time implementation.

Monitoring of volcanic emissions for risk assessment at Popocatépetl volcano (Mexico)

NASA Astrophysics Data System (ADS)

Delgado, Hugo; Campion, Robin; Fickel, Matthias; Cortés Ramos, Jorge; Alvarez Nieves, José Manuel; Taquet, Noemi; Grutter, Michel; Osiris García Gómez, Israel; Darío Sierra Mondragón, Rubén; Meza Hernández, Israel

2015-04-01

In January 2014, the Mexican Agency FOPREDEN (Natural Disaster Prevention Fund) accepted to fund a project to renew, upgrade and complement the gas monitoring facilities. The UNAM-CENAPRED (National Center for Disaster Prevention) gas monitoring system currently consists of: • A COSPEC instrument and two mini-DOAS used for mobile traverse measurements • An SO2 camera used for punctual campaign • A network of three permanent scanning mini-DOAS (NOVAC type 1 instrument) and one permanent mini-DOAS (NOVAC type II, currently under repair). The activity planed in the framework of the new project, of which several of them are already successfully implemented, include: • Completely refurbished permanent scanning mini-DOAS network consisting of four stations and the punctual deployment of three RADES (Rapid Deployment System) for assessing plume geometry and chemistry or for responding to emergency situations. • Prolongation of the mobile traverse measurements in order to continuously update the 20 years-long SO2 flux database obtained with the COSPEC, now coupled with a mobile DOAS for redundancy. • The development and installation of a permanent SO2 camera, for monitoring in real time the short timescale variations of the SO2 emissions. • The installation of two permanent FTIR spectrometers, one measuring the plume thermal emissions and the other measuring with the solar occultation geometry, for frequent measurements of molecular ratio between SO2, HCl, HF and SiF4 • The exploitation in near-real time of the satellite imagery (OMI, MODIS and ASTER) available for the volcano. A special attention will be paid to increase the reliability and graphical representation of these data stream in order to facilitate their use for decision-making by the civil protection authority in charge of the volcano.

Type 3 Secretion System (T3SS) of Bradyrhizobium sp. DOA9 and Its Roles in Legume Symbiosis and Rice Endophytic Association

PubMed Central

Songwattana, Pongpan; Noisangiam, Rujirek; Teamtisong, Kamonluck; Prakamhang, Janpen; Teulet, Albin; Tittabutr, Panlada; Piromyou, Pongdet; Boonkerd, Nantakorn; Giraud, Eric; Teaumroong, Neung

2017-01-01

The Bradyrhizobium sp. DOA9 strain isolated from a paddy field has the ability to nodulate a wide spectrum of legumes. Unlike other bradyrhizobia, this strain has a symbiotic plasmid harboring nod, nif, and type 3 secretion system (T3SS) genes. This T3SS cluster contains all the genes necessary for the formation of the secretory apparatus and the transcriptional activator (TtsI), which is preceded by a nod-box motif. An in silico search predicted 14 effectors putatively translocated by this T3SS machinery. In this study, we explored the role of the T3SS in the symbiotic performance of DOA9 by evaluating the ability of a T3SS mutant (ΩrhcN) to nodulate legumes belonging to Dalbergioid, Millettioid, and Genistoid tribes. Among the nine species tested, four (Arachis hypogea, Vigna radiata, Crotalaria juncea, and Macroptilium atropurpureum) responded positively to the rhcN mutation (ranging from suppression of plant defense reactions, an increase in the number of nodules and a dramatic improvement in nodule development and infection), one (Stylosanthes hamata) responded negatively (fewer nodules and less nitrogen fixation) and four species (Aeschynomene americana, Aeschynomene afraspera, Indigofera tinctoria, and Desmodium tortuosum) displayed no phenotype. We also tested the role of the T3SS in the ability of the DOA9 strain to endophytically colonize rice roots, but detected no effect of the T3SS mutation, in contrast to what was previously reported in the Bradyrhizobium SUTN9-2 strain. Taken together, these data indicate that DOA9 contains a functional T3SS that interferes with the ability of the strain to interact symbiotically with legumes but not with rice. PMID:28979252

Type 3 Secretion System (T3SS) of Bradyrhizobium sp. DOA9 and Its Roles in Legume Symbiosis and Rice Endophytic Association.

PubMed

Songwattana, Pongpan; Noisangiam, Rujirek; Teamtisong, Kamonluck; Prakamhang, Janpen; Teulet, Albin; Tittabutr, Panlada; Piromyou, Pongdet; Boonkerd, Nantakorn; Giraud, Eric; Teaumroong, Neung

2017-01-01

The Bradyrhizobium sp. DOA9 strain isolated from a paddy field has the ability to nodulate a wide spectrum of legumes. Unlike other bradyrhizobia, this strain has a symbiotic plasmid harboring nod , nif , and type 3 secretion system (T3SS) genes. This T3SS cluster contains all the genes necessary for the formation of the secretory apparatus and the transcriptional activator (TtsI), which is preceded by a nod -box motif. An in silico search predicted 14 effectors putatively translocated by this T3SS machinery. In this study, we explored the role of the T3SS in the symbiotic performance of DOA9 by evaluating the ability of a T3SS mutant (Ω rhcN ) to nodulate legumes belonging to Dalbergioid, Millettioid, and Genistoid tribes. Among the nine species tested, four ( Arachis hypogea , Vigna radiata , Crotalaria juncea , and Macroptilium atropurpureum ) responded positively to the rhcN mutation (ranging from suppression of plant defense reactions, an increase in the number of nodules and a dramatic improvement in nodule development and infection), one ( Stylosanthes hamata ) responded negatively (fewer nodules and less nitrogen fixation) and four species ( Aeschynomene americana , Aeschynomene afraspera , Indigofera tinctoria , and Desmodium tortuosum ) displayed no phenotype. We also tested the role of the T3SS in the ability of the DOA9 strain to endophytically colonize rice roots, but detected no effect of the T3SS mutation, in contrast to what was previously reported in the Bradyrhizobium SUTN9-2 strain. Taken together, these data indicate that DOA9 contains a functional T3SS that interferes with the ability of the strain to interact symbiotically with legumes but not with rice.

Novel angle estimation for bistatic MIMO radar using an improved MUSIC

NASA Astrophysics Data System (ADS)

Li, Jianfeng; Zhang, Xiaofei; Chen, Han

2014-09-01

In this article, we study the problem of angle estimation for bistatic multiple-input multiple-output (MIMO) radar and propose an improved multiple signal classification (MUSIC) algorithm for joint direction of departure (DOD) and direction of arrival (DOA) estimation. The proposed algorithm obtains initial estimations of angles obtained from the signal subspace and uses the local one-dimensional peak searches to achieve the joint estimations of DOD and DOA. The angle estimation performance of the proposed algorithm is better than that of estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm, and is almost the same as that of two-dimensional MUSIC. Furthermore, the proposed algorithm can be suitable for irregular array geometry, obtain automatically paired DOD and DOA estimations, and avoid two-dimensional peak searching. The simulation results verify the effectiveness and improvement of the algorithm.

[Determination of the error of aerosol extinction coefficient measured by DOAS].

PubMed

Si, Fu-qi; Liu, Jian-guo; Xie, Pin-hua; Zhang, Yu-jun; Wang, Mian; Liu, Wen-qing; Hiroaki, Kuze; Liu, Cheng; Nobuo, Takeuchi

2006-10-01

The method of defining the error of aerosol extinction coefficient measured by differential optical absorption spectroscopy (DOAS) is described. Some factors which could bring errors to result, such as variation of source, integral time, atmospheric turbulence, calibration of system parameter, displacement of system, and back scattering of particles, are analyzed. The error of aerosol extinction coefficient, 0.03 km(-1), is determined by theoretical analysis and practical measurement.

The ESA FRM4DOAS project: Towards a quality-controlled MAXDOAS Centralized Processing System

NASA Astrophysics Data System (ADS)

Hendrick, Francois; Fayt, Caroline; Friess, Udo; Kreher, Karin; Piters, Ankie; Richter, Andreas; Wagner, Thomas; Cede, Alexander; Spinei, Elena; von Bismarck, Jonas; Fehr, Thorsten; Van Roozendael, Michel

2017-04-01

The Fiducial Reference Measurements for Ground-Based DOAS Air-Quality Observations (FRM4DOAS) is a two-year project funded by the European Space Agency (ESA). Started in July 2016, FRM4DOAS aims at further harmonizing MAXDOAS measurements and data sets, through (1) the specification of best practices for instrument operation, (2) the selection of state-of-the art retrieval algorithms, procedures, and settings, (3) the demonstration of a centralised rapid-delivery (6-24h latency) processing system for MAXDOAS instruments to be operated within the international Network for the Detection of Atmospheric Composition Change (NDACC). The project also links with the Pandonia initiative. In a first phase, the system concentrates on the development of 3 key products: NO2 vertical profiles, total O3 and tropospheric HCHO profiles, which will be retrieved at 11 MAXDOAS pilot stations. The system will also be tested and validated on data from the CINDI-2 campaign, and designed to allow further extension after commissioning. These activities will help and guarantee that homogenous, fully traceable, and quality-controlled datasets are generated from reference ground-based UV-vis instruments, which will play a crucial role in the validation of future ESA/Copernicus Sentinel satellite missions S-5P, S-4, and S-5.

A Channelization-Based DOA Estimation Method for Wideband Signals

PubMed Central

Guo, Rui; Zhang, Yue; Lin, Qianqiang; Chen, Zengping

2016-01-01

In this paper, we propose a novel direction of arrival (DOA) estimation method for wideband signals with sensor arrays. The proposed method splits the wideband array output into multiple frequency sub-channels and estimates the signal parameters using a digital channelization receiver. Based on the output sub-channels, a channelization-based incoherent signal subspace method (Channelization-ISM) and a channelization-based test of orthogonality of projected subspaces method (Channelization-TOPS) are proposed. Channelization-ISM applies narrowband signal subspace methods on each sub-channel independently. Then the arithmetic mean or geometric mean of the estimated DOAs from each sub-channel gives the final result. Channelization-TOPS measures the orthogonality between the signal and the noise subspaces of the output sub-channels to estimate DOAs. The proposed channelization-based method isolates signals in different bandwidths reasonably and improves the output SNR. It outperforms the conventional ISM and TOPS methods on estimation accuracy and dynamic range, especially in real environments. Besides, the parallel processing architecture makes it easy to implement on hardware. A wideband digital array radar (DAR) using direct wideband radio frequency (RF) digitization is presented. Experiments carried out in a microwave anechoic chamber with the wideband DAR are presented to demonstrate the performance. The results verify the effectiveness of the proposed method. PMID:27384566

Sample Entropy Analysis of EEG Signals via Artificial Neural Networks to Model Patients' Consciousness Level Based on Anesthesiologists Experience

PubMed Central

Jiang, George J. A.; Fan, Shou-Zen; Abbod, Maysam F.; Huang, Hui-Hsun; Lan, Jheng-Yan; Tsai, Feng-Fang; Chang, Hung-Chi; Yang, Yea-Wen; Chuang, Fu-Lan; Chiu, Yi-Fang; Jen, Kuo-Kuang; Wu, Jeng-Fu; Shieh, Jiann-Shing

2015-01-01

Electroencephalogram (EEG) signals, as it can express the human brain's activities and reflect awareness, have been widely used in many research and medical equipment to build a noninvasive monitoring index to the depth of anesthesia (DOA). Bispectral (BIS) index monitor is one of the famous and important indicators for anesthesiologists primarily using EEG signals when assessing the DOA. In this study, an attempt is made to build a new indicator using EEG signals to provide a more valuable reference to the DOA for clinical researchers. The EEG signals are collected from patients under anesthetic surgery which are filtered using multivariate empirical mode decomposition (MEMD) method and analyzed using sample entropy (SampEn) analysis. The calculated signals from SampEn are utilized to train an artificial neural network (ANN) model through using expert assessment of consciousness level (EACL) which is assessed by experienced anesthesiologists as the target to train, validate, and test the ANN. The results that are achieved using the proposed system are compared to BIS index. The proposed system results show that it is not only having similar characteristic to BIS index but also more close to experienced anesthesiologists which illustrates the consciousness level and reflects the DOA successfully. PMID:25738152

Using a focal-plane array to estimate antenna pointing errors

NASA Technical Reports Server (NTRS)

Zohar, S.; Vilnrotter, V. A.

1991-01-01

The use of extra collecting horns in the focal plane of an antenna as a means of determining the Direction of Arrival (DOA) of the signal impinging on it, provided it is within the antenna beam, is considered. Our analysis yields a relatively simple algorithm to extract the DOA from the horns' outputs. An algorithm which, in effect, measures the thermal noise of the horns' signals and determines its effect on the uncertainty of the extracted DOA parameters is developed. Both algorithms were implemented in software and tested in simulated data. Based on these tests, it is concluded that this is a viable approach to the DOA determination. Though the results obtained are of general applicability, the particular motivation for the present work is their application to the pointing of a mechanically deformed antenna. It is anticipated that the pointing algorithm developed for a deformed antenna could be obtained as a small perturbation of the algorithm developed for an undeformed antenna. In this context, it should be pointed out that, with a deformed antenna, the array of horns and its associated circuitry constitute the main part of the deformation-compensation system. In this case, the pointing system proposed may be viewed as an additional task carried out by the deformation-compensation hardware.

Diurnal, seasonal and long-term variations of global formaldehyde columns inferred from combined OMI and GOME-2 observations

NASA Astrophysics Data System (ADS)

De Smedt, I.; Stavrakou, T.; Hendrick, F.; Danckaert, T.; Vlemmix, T.; Pinardi, G.; Theys, N.; Lerot, C.; Gielen, C.; Vigouroux, C.; Hermans, C.; Fayt, C.; Veefkind, P.; Müller, J.-F.; Van Roozendael, M.

2015-11-01

We present the new version (v14) of the BIRA-IASB algorithm for the retrieval of formaldehyde (H2CO) columns from spaceborne UV-visible sensors. Applied to OMI measurements from Aura and to GOME-2 measurements from MetOp-A and MetOp-B, this algorithm is used to produce global distributions of H2CO representative of mid-morning and early afternoon conditions. Its main features include (1) a new iterative DOAS scheme involving three fitting intervals to better account for the O2-O2 absorption, (2) the use of earthshine radiances averaged in the equatorial Pacific as reference spectra, and (3) a destriping correction and background normalisation resolved in the across-swath position. For the air mass factor calculation, a priori vertical profiles calculated by the IMAGES chemistry transport model at 09:30 and 13:30 LT are used. Although the resulting GOME-2 and OMI H2CO vertical columns are found to be highly correlated, some systematic differences are observed. Afternoon columns are generally larger than morning ones, especially in mid-latitude regions. In contrast, over tropical rainforests, morning H2CO columns significantly exceed those observed in the afternoon. These differences are discussed in terms of the H2CO column variation between mid-morning and early afternoon, using ground-based MAX-DOAS measurements available from seven stations in Europe, China and Africa. Validation results confirm the capacity of the combined satellite measurements to resolve diurnal variations in H2CO columns. Furthermore, vertical profiles derived from MAX-DOAS measurements in the Beijing area and in Bujumbura are used for a more detailed validation exercise. In both regions, we find an agreement better than 15 % when MAX-DOAS profiles are used as a priori for the satellite retrievals. Finally, regional trends in H2CO columns are estimated for the 2004-2014 period using SCIAMACHY and GOME-2 data for morning conditions, and OMI for early afternoon conditions. Consistent features are observed, such as an increase of the columns in India and central-eastern China, and a decrease in the eastern US and Europe. We find that the higher horizontal resolution of OMI combined with a better sampling and a more favourable illumination at midday allow for more significant trend estimates, especially over Europe and North America. Importantly, in some parts of the Amazonian forest, we observe with both time series a significant downward trend in H2CO columns, spatially correlated with areas affected by deforestation.

Diurnal, seasonal and long-term variations of global formaldehyde columns inferred from combined OMI and GOME-2 observations

NASA Astrophysics Data System (ADS)

De Smedt, I.; Stavrakou, T.; Hendrick, F.; Danckaert, T.; Vlemmix, T.; Pinardi, G.; Theys, N.; Lerot, C.; Gielen, C.; Vigouroux, C.; Hermans, C.; Fayt, C.; Veefkind, P.; Müller, J.-F.; Van Roozendael, M.

2015-04-01

We present the new version (v14) of the BIRA-IASB algorithm for the retrieval of formaldehyde (H2CO) columns from spaceborne UV-Visible sensors. Applied to OMI measurements from Aura and to GOME-2 measurements from MetOp-A and B, this algorithm is used to produce global distributions of H2CO representative of mid-morning and early afternoon conditions. Its main features include (1) a new iterative DOAS scheme involving three fitting intervals to better account for the O2-O2 absorption, (2) the use of earthshine radiances averaged in the equatorial Pacific as reference spectra, (3) a destriping correction and background normalisation resolved in the along-swath position. For the air mass factor calculation, a priori vertical profiles calculated by the IMAGES chemistry transport model at 9.30 a.m. and 13.30 p.m. are used. Although the resulting GOME-2 and OMI H2CO vertical columns are found to be highly correlated, some systematic differences are observed. Afternoon columns are generally larger than morning ones, especially in mid-latitude regions. In contrast, over tropical rainforests, morning H2CO columns significantly exceed those observed in the afternoon. These differences are discussed in terms of the H2CO column variation between mid-morning and early afternoon, using ground-based MAX-DOAS measurements available from seven stations in Europe, China and Africa. Validation results confirm the capacity of the combined satellite measurements to resolve diurnal variations in H2CO columns. Furthermore, vertical profiles derived from MAX-DOAS measurements in the Beijing area and in Bujumbura are used for a more detailed validation exercise. In both regions, we find an agreement better than 15% when MAX-DOAS profiles are used as a priori for the satellite retrievals. Finally regional trends in H2CO columns are estimated for the 2004-2014 period using SCIAMACHY and GOME-2 data for morning conditions, and OMI for early afternoon conditions. Consistent features are observed such as an increase of the columns in India and Central-East China, and a decrease in Eastern US and Europe. We find that the higher horizontal resolution of OMI combined to a better sampling and a more favourable illumination at mid-day allow for more significant trend estimates, especially over Europe and North America. Importantly, in some parts of the Amazonian forest, we observe with both time series a significant downward trend in H2CO columns, spatially correlated with areas affected by deforestation.

Parallel Implementation of the Wideband DOA Algorithm on the IBM Cell BE Processor

DTIC Science & Technology

2010-05-01

Abstract—The Multiple Signal Classification ( MUSIC ) algorithm is a powerful technique for determining the Direction of Arrival (DOA) of signals...Broadband Engine Processor (Cell BE). The process of adapting the serial based MUSIC algorithm to the Cell BE will be analyzed in terms of parallelism and...using Multiple Signal Classification MUSIC algorithm [4] • Computation of Focus matrix • Computation of number of sources • Separation of Signal

A Robust Real Time Direction-of-Arrival Estimation Method for Sequential Movement Events of Vehicles.

PubMed

Liu, Huawei; Li, Baoqing; Yuan, Xiaobing; Zhou, Qianwei; Huang, Jingchang

2018-03-27

Parameters estimation of sequential movement events of vehicles is facing the challenges of noise interferences and the demands of portable implementation. In this paper, we propose a robust direction-of-arrival (DOA) estimation method for the sequential movement events of vehicles based on a small Micro-Electro-Mechanical System (MEMS) microphone array system. Inspired by the incoherent signal-subspace method (ISM), the method that is proposed in this work employs multiple sub-bands, which are selected from the wideband signals with high magnitude-squared coherence to track moving vehicles in the presence of wind noise. The field test results demonstrate that the proposed method has a better performance in emulating the DOA of a moving vehicle even in the case of severe wind interference than the narrowband multiple signal classification (MUSIC) method, the sub-band DOA estimation method, and the classical two-sided correlation transformation (TCT) method.

Development of a Differential Optical Absorption Spectroscopy System Using HighLuminance LED for Measurement of NO2

NASA Astrophysics Data System (ADS)

Fukuchi, Tetsuo; Nayuki, Takuya; Mori, Hideto; Goto, Naohiko; Fujii, Takashi; Nemoto, Koshichi

A differential optical absorption spectroscopy (DOAS) system for measurement of atmospheric NO2 was developed. The system uses a battery-operated, high luminance LED and a fiber-coupled spectrometer, and is portable. Laboratory experiments using a gas cell of length 0.22 m with varying NO2 concentrations were performed to evaluate the sensitivity of the DOAS system. The DOAS measurement results are in agreement with NO2 concentrations obtained simultaneously by a FT-IR (Fourier Transform Infrared) system for NO2 concentrations down to 20 ppm. Experiments with an optical path length of 93 m were also performed, and NO2 concentrations down to 0.20 ppm were measured. Since measurement of atmospheric NO2, which is in the order of several tens of ppb, requires optical path lengths of several hundred m, system improvements to improve the signal detection are necessary.

Sparse Bayesian learning for DOA estimation with mutual coupling.

PubMed

Dai, Jisheng; Hu, Nan; Xu, Weichao; Chang, Chunqi

2015-10-16

Sparse Bayesian learning (SBL) has given renewed interest to the problem of direction-of-arrival (DOA) estimation. It is generally assumed that the measurement matrix in SBL is precisely known. Unfortunately, this assumption may be invalid in practice due to the imperfect manifold caused by unknown or misspecified mutual coupling. This paper describes a modified SBL method for joint estimation of DOAs and mutual coupling coefficients with uniform linear arrays (ULAs). Unlike the existing method that only uses stationary priors, our new approach utilizes a hierarchical form of the Student t prior to enforce the sparsity of the unknown signal more heavily. We also provide a distinct Bayesian inference for the expectation-maximization (EM) algorithm, which can update the mutual coupling coefficients more efficiently. Another difference is that our method uses an additional singular value decomposition (SVD) to reduce the computational complexity of the signal reconstruction process and the sensitivity to the measurement noise.

The impact of vibrational Raman scattering of air on DOAS measurements of atmospheric trace gases

NASA Astrophysics Data System (ADS)

Lampel, J.; Frieß, U.; Platt, U.

2015-09-01

In remote sensing applications, such as differential optical absorption spectroscopy (DOAS), atmospheric scattering processes need to be considered. After inelastic scattering on N2 and O2 molecules, the scattered photons occur as additional intensity at a different wavelength, effectively leading to "filling-in" of both solar Fraunhofer lines and absorptions of atmospheric constituents, if the inelastic scattering happens after the absorption. Measured spectra in passive DOAS applications are typically corrected for rotational Raman scattering (RRS), also called Ring effect, which represents the main contribution to inelastic scattering. Inelastic scattering can also occur in liquid water, and its influence on DOAS measurements has been observed over clear ocean water. In contrast to that, vibrational Raman scattering (VRS) of N2 and O2 has often been thought to be negligible, but it also contributes. Consequences of VRS are red-shifted Fraunhofer structures in scattered light spectra and filling-in of Fraunhofer lines, additional to RRS. At 393 nm, the spectral shift is 25 and 40 nm for VRS of O2 and N2, respectively. We describe how to calculate VRS correction spectra according to the Ring spectrum. We use the VRS correction spectra in the spectral range of 420-440 nm to determine the relative magnitude of the cross-sections of VRS of O2 and N2 and RRS of air. The effect of VRS is shown for the first time in spectral evaluations of Multi-Axis DOAS data from the SOPRAN M91 campaign and the MAD-CAT MAX-DOAS intercomparison campaign. The measurements yield in agreement with calculated scattering cross-sections that the observed VRS(N2) cross-section at 393 nm amounts to 2.3 ± 0.4 % of the cross-section of RRS at 433 nm under tropospheric conditions. The contribution of VRS(O2) is also found to be in agreement with calculated scattering cross-sections. It is concluded, that this phenomenon has to be included in the spectral evaluation of weak absorbers as it reduces the measurement error significantly and can cause apparent differential optical depth of up to 3 ×10-4. Its influence on the spectral retrieval of IO, glyoxal, water vapour and NO2 in the blue wavelength range is evaluated for M91. For measurements with a large Ring signal a significant and systematic bias of NO2 dSCDs (differential slant column densities) up to (-3.8 ± 0.4) × 1014 molec cm-2 is observed if this effect is not considered. The effect is typically negligible for DOAS fits with an RMS (root mean square) larger than 4 × 10-4.

MAX-DOAS NO2 observations over Guangzhou, China; ground-based and satellite comparisons

NASA Astrophysics Data System (ADS)

Drosoglou, Theano; Elissavet Koukouli, Maria; Kouremeti, Natalia; Bais, Alkiviadis F.; Zyrichidou, Irene; Balis, Dimitris; van der A, Ronald J.; Xu, Jin; Li, Ang

2018-04-01

In this study, the tropospheric NO2 vertical column density (VCD) over an urban site in Guangzhou megacity in China is investigated by means of MAX-DOAS measurements during a campaign from late March 2015 to mid-March 2016. A MAX-DOAS system was deployed at the Guangzhou Institute of Geochemistry of the Chinese Academy of Sciences and operated there for about 1 year, during the spring and summer months. The tropospheric NO2 VCDs retrieved by the MAX-DOAS are presented and compared with space-borne observations from GOME-2/MetOp-A, GOME-2/MetOp-B and OMI/Aura satellite sensors. The comparisons reveal good agreement between satellite and MAX-DOAS observations over Guangzhou, with correlation coefficients ranging between 0.795 for GOME-2B and 0.996 for OMI. However, the tropospheric NO2 loadings are underestimated by the satellite sensors on average by 25.1, 10.3 and 5.7 %, respectively, for OMI, GOME-2A and GOME-2B. Our results indicate that GOME-2B retrievals are closer to those of the MAX-DOAS instrument due to the lower tropospheric NO2 concentrations during the days with valid GOME-2B observations. In addition, the effect of the main coincidence criteria is investigated, namely the cloud fraction (CF), the distance (d) between the satellite pixel center and the ground-based measurement site, as well as the time period within which the MAX-DOAS data are averaged around the satellite overpass time. The effect of CF and time window criteria is more profound on the selection of OMI overpass data, probably due to its smaller pixel size. The available data pairs are reduced to half and about one-third for CF ≤ 0.3 and CF ≤ 0.2, respectively, while, compared to larger CF thresholds, the correlation coefficient is improved to 0.996 from about 0.86, the slope value is very close to unity ( ˜ 0.98) and the mean satellite underestimation is reduced to about half (from ˜ 7 to ˜ 3.5 × 1015 molecules cm-2). On the other hand, the distance criterion affects mostly GOME-2B data selection, because GOME-2B pixels are quite evenly distributed among the different radii used in the sensitivity test. More specifically, the number of collocations is notably reduced when stricter radius limits are applied, the r value is improved from 0.795 (d ≤ 50 km) to 0.953 (d ≤ 20 km), and the absolute mean bias decreases about 6 times for d ≤ 30 km compared to the reference case (d ≤ 50 km).

Development of SAP-DoA techniques for GPR data processing within COST Action TU1208

NASA Astrophysics Data System (ADS)

Meschino, Simone; Pajewski, Lara; Marciniak, Marian

2016-04-01

This work focuses on the use of Sub-Array Processing (SAP) and Direction of Arrival (DoA) approaches for the processing of Ground-Penetrating Radar data, with the purpose of locating metal scatterers embedded in concrete or buried in the ground. Research activities have been carried out during two Short-Term Scientific Missions (STSMs) funded by the COST (European COoperation in Science and Technology) Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar" in May 2015 and January 2016. In applications involving smart antennas and in the presence of several transmitters operating simultaneously, it is important for a receiving array to be able to estimate the Direction of Arrival (DoA) of the incoming signals, in order to decipher how many emitters are present and predict their positions. A number of methods have been devised for DoA estimation: the MUltiple SIgnal Classification (MUSIC) and Estimation of Signal Parameters via Rotational Invariance Technique (ESPRIT) are amongst the most popular ones [1]. In the scenario considered by us, the electromagnetic sources are the currents induced on metal elements embedded in concrete or buried in the ground. GPR radargrams are processed, to estimate the DoAs of the electric field back-scattered by the sought targets. In order to work in near-field conditions, a sub-array processing (SAP) approach is adopted: the radargram is partitioned in sub-radargrams composed of few A-scans each, the dominant DoA is predicted for each sub-radargram. The estimated angles are triangulated, obtaining a set of crossings with intersections condensed around object locations. This pattern is filtered, in order to remove a noisy background of unwanted crossings, and is processed by applying the statistical procedure described in [2]. We tested our approach on synthetic GPR radargrams, obtained by using the freeware simulator gprMax implementing the Finite-Difference Time-Domain method [3]. In particular, we worked with the reference data of TU1208 Concrete Cells 1.1-1.3 [4]. Preliminary results and a description of the method have been presented in [5]. Further results have been obtained by processing radargrams obtained in the presence of modified versions of the TU1208 Concrete Cells, where we changed the positions of the reinforcing elements. As expected, we achieved better results when the distance between the scatterers was larger and their interaction weaker. By analysing in depth the results obtained for the enlarged versions of Cells 1.1-1.3, we could assess in a comprehensive way the accuracy and limits of our approach in the presence of multiple scatterers, versus their relative distance. During future STSMs, we look forward to testing our approach on experimental data. We also plan to improve the method, in order to exploit in a more advanced way the multi-frequency information enclosed in the GPR data. A final STSM will be devoted to implementing a graphical-user interface and writing a user manual, as we intend to release our codes for free public download by the end of the Action.

Characterisation of Central-African emissions based on MAX-DOAS measurements, satellite observations and model simulations over Bujumbura, Burundi.

NASA Astrophysics Data System (ADS)

Gielen, Clio; Hendrick, Francois; Pinardi, Gaia; De Smedt, Isabelle; Stavrakou, Trissevgeni; Yu, Huan; Fayt, Caroline; Hermans, Christian; Bauwens, Maité; Ndenzako, Eugene; Nzohabonayo, Pierre; Akimana, Rachel; Niyonzima, Sébastien; Müller, Jean-Francois; Van Roozendael, Michel

2016-04-01

Central Africa is known for its strong biogenic, pyrogenic, and to a lesser extent anthropogenic emissions. Satellite observations of species like nitrogen dioxide (NO2) and formaldehyde (HCHO), as well as inverse modelling results have shown that there are large uncertainties associated with the emissions in this region. There is thus a need for additional measurements, especially from the ground, in order to better characterise the biomass-burning and biogenic products emitted in this area. We present MAX-DOAS measurements of NO2, HCHO, and aerosols performed in Central Africa, in the city of Bujumbura, Burundi (3°S, 29°E, 850m). A MAX-DOAS instrument has been operating at this location by BIRA-IASB since late 2013. Aerosol-extinction and trace-gases vertical profiles are retrieved by applying the optimal-estimation-based profiling tool bePRO to the measured O4, NO2 and HCHO slant-column densities. The MAX-DOAS vertical columns and profiles are used for investigating the diurnal and seasonal cycles of NO2, HCHO, and aerosols. Regarding the aerosols, the retrieved AODs are compared to co-located AERONET sun photometer measurements for verification purpose, while in the case of NO2 and HCHO, the MAX-DOAS vertical columns and profiles are used for validating GOME-2 and OMI satellite observations. To characterise the biomass-burning and biogenic emissions in the Bujumbura region, the trace gases and aerosol MAX-DOAS retrievals are used in combination to MODIS fire counts/radiative-power and GOME-2/OMI NO2 and HCHO satellite data, as well as simulations from the NOAA backward trajectory model HYSPLIT. First results show that HCHO seasonal variation around local noon is driven by the alternation of rain and dry periods, the latter being associated with intense biomass-burning agricultural activities and forest fires in the south/south-east and transport from this region to Bujumbura. In contrast, NO2 is seen to depend mainly on local emissions close to the city, due to the short lifetime of this species (typically 1-2 hours). Regarding the biogenic emissions, it is found that they play only a minor role in the observed HCHO seasonality. These results are further assessed using the tropospheric 3D-CTM IMAGES.

Development of a digital mobile solar tracker

NASA Astrophysics Data System (ADS)

Baidar, S.; Kille, N.; Ortega, I.; Sinreich, R.; Thomson, D.; Hannigan, J.; Volkamer, R.

2015-11-01

We have constructed and deployed a fast digital solar tracker aboard a moving ground-based platform. The tracker consists of two rotating mirrors, a lens, an imaging camera, and a motion compensation system that provides the Euler angles of the mobile platform in real time. The tracker can be simultaneously coupled to UV-Vis and FTIR spectrometers making it a versatile tool to measure the absorption of trace gases using solar incoming radiation. The integrated system allows the tracker to operate autonomously while the mobile laboratory is in motion. Mobile direct sun Differential Optical Absorption Spectroscopy (mobile DS-DOAS) observations using this tracker were conducted during summer 2014 as part of the Front Range Photochemistry and Pollution Experiment (FRAPPE) in Colorado, USA. We demonstrate an angular precision of 0.052° (about 1/10 of the solar disk diameter) during research drives, and verify this tracking precision from measurements of the center to limb darkening (CLD, the changing appearance of Fraunhofer lines) in the mobile DS-DOAS spectra. The high photon flux from direct sun observation enables measurements of nitrogen dioxide (NO2) slant columns with high temporal resolution, and reveals spatial detail in the variations of NO2 vertical column densities (VCDs). The NO2 VCD from DS-DOAS is compared with a co-located MAX-DOAS instrument. Overall good agreement is observed amid a highly heterogeneous air mass.

Development of a digital mobile solar tracker

NASA Astrophysics Data System (ADS)

Baidar, Sunil; Kille, Natalie; Ortega, Ivan; Sinreich, Roman; Thomson, David; Hannigan, James; Volkamer, Rainer

2016-03-01

We have constructed and deployed a fast digital solar tracker aboard a moving ground-based platform. The tracker consists of two rotating mirrors, a lens, an imaging camera, and a motion compensation system that provides the Euler angles of the mobile platform in real time. The tracker can be simultaneously coupled to UV-Vis and Fourier transform infrared spectrometers, making it a versatile tool to measure the absorption of trace gases using solar incoming radiation. The integrated system allows the tracker to operate autonomously while the mobile laboratory is in motion. Mobile direct sun differential optical absorption spectroscopy (mobile DS-DOAS) observations using this tracker were conducted during summer 2014 as part of the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) in Colorado, USA. We demonstrate an angular precision of 0.052° (about 1/10 of the solar disk diameter) during research drives and verify this tracking precision from measurements of the center to limb darkening (CLD, the changing appearance of Fraunhofer lines) in the mobile DS-DOAS spectra. The high photon flux from direct sun observation enables measurements of nitrogen dioxide (NO2) slant columns with high temporal resolution and reveals spatial detail in the variations of NO2 vertical column densities (VCDs). The NO2 VCD from DS-DOAS is compared with a co-located MAX-DOAS instrument. Overall good agreement is observed amid a highly heterogeneous air mass.

Comparison of stratospheric NO2 profiles above Kiruna, Sweden retrieved from ground-based zenith sky DOAS measurements, SAOZ balloon measurements and SCIAMACHY limb observations

NASA Astrophysics Data System (ADS)

Gu, Myojeong; Enell, Carl-Fredrik; Hendrick, François; Pukite, Janis; Van Roozendael, Michel; Platt, Ulrich; Raffalski, Uwe; Wagner, Thomas

2015-04-01

Stratospheric NO2 not only destroys ozone but acts as a buffer against halogen catalyzed ozone loss by converting halogen species into stable nitrates. These two roles of stratospheric NO2 depend on the altitude. Hence, the objective of this study is to investigate the vertical distribution of stratospheric NO2. We compare the NO2 profiles derived from the zenith sky DOAS with those obtained from, SAOZ balloon measurements and satellite limb observations. Vertical profiles of stratospheric NO2 are retrieved from ground-based zenith sky DOAS observations operated at Kiruna, Sweden (68.84°N, 20.41°E) since 1996. To determine the profile of stratospheric NO2 measured from ground-based zenith sky DOAS, we apply the Optimal Estimation Method (OEM) to retrieval of vertical profiles of stratospheric NO2 which has been developed by IASB-BIRA. The basic principle behind this profiling approach is the dependence of the mean scattering height on solar zenith angle (SZA). We compare the retrieved profiles to two additional datasets of stratospheric NO2 profile. The first one is derived from satellite limb observations by SCIAMACHY (Scanning Imaging Absorption spectrometer for Atmospheric CHartographY) on EnviSAT. The second is derived from the SAOZ balloon measurements (using a UV/Visible spectrometer) performed at Kiruna in Sweden.

Array processing for RFID tag localization exploiting multi-frequency signals

NASA Astrophysics Data System (ADS)

Zhang, Yimin; Li, Xin; Amin, Moeness G.

2009-05-01

RFID is an increasingly valuable business and technology tool for electronically identifying, locating, and tracking products, assets, and personnel. As a result, precise positioning and tracking of RFID tags and readers have received considerable attention from both academic and industrial communities. Finding the position of RFID tags is considered an important task in various real-time locating systems (RTLS). As such, numerous RFID localization products have been developed for various applications. The majority of RFID positioning systems is based on the fusion of pieces of relevant information, such as the range and the direction-of-arrival (DOA). For example, trilateration can determine the tag position by using the range information of the tag estimated from three or more spatially separated reader antennas. Triangulation is another method to locate RFID tags that use the direction-of-arrival (DOA) information estimated at multiple spatially separated locations. The RFID tag positions can also be determined through hybrid techniques that combine the range and DOA information. The focus of this paper to study the design and performance of the localization of passive RFID tags using array processing techniques in a multipath environment, and exploiting multi-frequency CW signals. The latter are used to decorrelate the coherent multipath signals for effective DOA estimation and for the purpose of accurate range estimation. Accordingly, the spatial and frequency dimensionalities are fully utilized for robust and accurate positioning of RFID tags.

Retrieval of tropospheric HCHO in El Salvador using ground based DOAS

NASA Astrophysics Data System (ADS)

Abarca, W.; Gamez, K.; Rudamas, C.

2017-12-01

Formaldehyde (HCHO) is the most abundant carbonyl in the atmosphere, being an intermediate product in the oxidation of most volatile organic compounds (VOCs). HCHO is carcinogenic, and highly water soluble [1]. HCHO can originate from biomass burning and fossil fuel combustion and has been observed from satellite and ground-based sensors by using the Differential Optical Absorption Spectroscopy (DOAS) technique [2].DOAS products can be used for air quality monitoring, validation of chemical transport models, validation of satellite tropospheric column density retrievals, among others [3]. In this study, we report on column density levels of HCHO measured by ground based Multi-Axis -DOAS in different locations of El Salvador in March, 2015. We have not observed large differences of the HCHO column density values at different viewing directions. This result points out a reasonably polluted and hazy atmosphere in the measuring sites, as reported by other authors [4]. Average values ranging from 1016 to 1017 molecules / cm2 has been obtained. The contribution of vehicular traffic and biomass burning to the column density levels in these sites of El Salvador will be discussed. [1] A. R. Garcia et al., Atmos. Chem. Phys. 6, 4545 (2006) [2] E. Peters et al., Atmos. Chem. Phys. 12, 11179 (2012) [3] T. Vlemmix, et al. Atmos. Meas. Tech., 8, 941-963, 2015 [4] A. Heckel et al., Atmos. Chem. Phys. 5, (2005)

Elevated aerosol layers modify the O2–O2 absorption measured by ground-based MAX-DOAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortega, Ivan; Berg, Larry K.; Ferrare, Richard A.

2016-06-01

The oxygen collisional complex (O2-O2, or O4) is a greenhouse gas, and a calibration trace gas used to infer aerosol and cloud properties by Differential Optical Absorption Spectroscopy (DOAS). Recent reports suggest the need for an O4 correction factor (CFO4) when comparing simulated and measured O4 differential slant column densities (dSCD) by passive DOAS. We investigate the sensitivity of O4 dSCD simulations at ultraviolet (360 nm) and visible (477 nm) wavelengths towards separately measured aerosol extinction profiles. Measurements were conducted by the University of Colorado 2D-MAX-DOAS instrument and NASA’s multispectral High Spectral Resolution Lidar (HSRL-2) during the Two Column Aerosolmore » Project (TCAP) at Cape Cod, MA in July 2012. During two case study days with (1) high aerosol load (17 July, AOD ~ 0.35 at 477 nm), and (2) near molecular scattering conditions (22 July, AOD < 0.10 at 477 nm) the measured and calculated O4 dSCDs agreed within 6.4±0.4% (360 nm) and 4.7±0.6% (477 nm) if the HSRL-2 profiles were used as input to the calculations. However, if in the calculations the aerosol is confined to the surface layer (while keeping AOD constant) we find 0.53« less

Landslide Failure Likelihoods Estimated Through Analysis of Suspended Sediment and Streamflow Time Series Data

NASA Astrophysics Data System (ADS)

Stark, C. P.; Rudd, S.; Lall, U.; Hovius, N.; Dadson, S.; Chen, M.-C.

Off-Axis DOAS measurements with non-artificial scattered light, based upon the renowned DOAS technique, allow to optimize the sensitivity of the technique for the trace gas profile in question by strongly increasing the light's path through the relevant atmosphere layers. Multi-Axis-(MAX) DOAS probe several directions simultaneously or sequentially to increase the spatial resolution. Several devices (ground based, air- borne and ship-built) are operated by our group in the framework of the SCIAMACHY validation. Radiative transfer models are an essential requirement for the interpretation of these measurements and their conversion into detailed profile data. Apart from some existing Monte Carlo Models most codes use analytical algorithms to solve the radia- tive transfer equation for given atmospheric conditions. For specific circumstances, e.g. photon scattering within clouds, these approaches are not efficient enough to pro- vide sufficient accuracy. Also horizontal gradients in atmospheric parameters have to be taken into account. To meet the needs of measurement situations for all kinds of scattered light DOAS platforms, a three dimensional full spherical Monte Carlo model was devised. Here we present Air Mass Factors (AMF) to calculate vertical column densities (VCD) from measured slant column densities (SCD). Sensitivity studies on the influence of the wavelength and telescope direction used, of the altitude of profile layers, albedo, refraction and basic aerosols are shown. Also modelled intensity series are compared with radiometer data.

MUSIC algorithm DoA estimation for cooperative node location in mobile ad hoc networks

NASA Astrophysics Data System (ADS)

Warty, Chirag; Yu, Richard Wai; ElMahgoub, Khaled; Spinsante, Susanna

In recent years the technological development has encouraged several applications based on distributed communications network without any fixed infrastructure. The problem of providing a collaborative early warning system for multiple mobile nodes against a fast moving object. The solution is provided subject to system level constraints: motion of nodes, antenna sensitivity and Doppler effect at 2.4 GHz and 5.8 GHz. This approach consists of three stages. The first phase consists of detecting the incoming object using a highly directive two element antenna at 5.0 GHz band. The second phase consists of broadcasting the warning message using a low directivity broad antenna beam using 2× 2 antenna array which then in third phase will be detected by receiving nodes by using direction of arrival (DOA) estimation technique. The DOA estimation technique is used to estimate the range and bearing of the incoming nodes. The position of fast arriving object can be estimated using the MUSIC algorithm for warning beam DOA estimation. This paper is mainly intended to demonstrate the feasibility of early detection and warning system using a collaborative node to node communication links. The simulation is performed to show the behavior of detecting and broadcasting antennas as well as performance of the detection algorithm. The idea can be further expanded to implement commercial grade detection and warning system

Care of elderly patients: a prospective audit of the prevalence of hypotension and the use of BIS intraoperatively in 25 hospitals in London.

PubMed

Wickham, Alex; Highton, David; Martin, Daniel

2016-01-01

Anaesthesia is frequently complicated by intraoperative hypotension (IOH) in the elderly, and this is associated with adverse outcome. The definition of IOH is controversial, and although management guidelines for IOH in the elderly exist, the frequency of IOH and typical clinically applied treatment thresholds are largely unknown in the UK. We audited frequency of intraoperative blood pressure against national guidelines in elderly patients undergoing surgery. Depth of anaesthesia (DOA) monitoring was also audited due to the association between low DOA values and IOH with increased mortality (as part of "double" and "triple low" phenomena) and because it is a suggested management strategy to reduce IOH. Twenty-five hospitals submitted data on 481 patients. Hypotension varied depending on the definition, but affected 400 patients (83.3 %) using the AAGBI standard. Furthermore, 2.9, 13.5, and 24.6 % had mean arterial blood pressures <50, <60, and <70 mmHg for 20 min, respectively, and 136 (28.4 %) had systolic blood pressure decrease by 20 % for 20 min. DOA monitors were used for 45 (9.4 %) patients. IOH is common and use of DOA monitors is less than implied by guidelines. Improved management of IOH may be a simple intervention with real potential to reduce morbidity in this vulnerable group.

Real-time monitoring of benzene, toluene, and p-xylene in a photoreaction chamber with a tunable mid-infrared laser and ultraviolet differential optical absorption spectroscopy.

PubMed

Parsons, Matthew T; Sydoryk, Ihor; Lim, Alan; McIntyre, Thomas J; Tulip, John; Jäger, Wolfgang; McDonald, Karen

2011-02-01

We describe the implementation of a mid-infrared laser-based trace gas sensor with a photoreaction chamber, used for reproducing chemical transformations of benzene, toluene, and p-xylene (BTX) gases that may occur in the atmosphere. The system performance was assessed in the presence of photoreaction products including aerosol particles. A mid-infrared external cavity quantum cascade laser (EC-QCL)-tunable from 9.41-9.88 μm (1012-1063 cm(-1))-was used to monitor gas phase concentrations of BTX simultaneously and in real time during chemical processing of these compounds with hydroxyl radicals in a photoreaction chamber. Results are compared to concurrent measurements using ultraviolet differential optical absorption spectroscopy (UV DOAS). The EC-QCL based system provides quantitation limits of approximately 200, 200, and 600 parts in 10(9) (ppb) for benzene, toluene, and p-xylene, respectively, which represents a significant improvement over our previous work with this laser system. Correspondingly, we observe the best agreement between the EC-QCL measurements and the UV DOAS measurements with benzene, followed by toluene, then p-xylene. Although BTX gas-detection limits are not as low for the EC-QCL system as for UV DOAS, an unidentified by-product of the photoreactions was observed with the EC-QCL, but not with the UV DOAS system.

MAX-DOAS measurements of HONO slant column densities during the MAD-CAT campaign: inter-comparison, sensitivity studies on spectral analysis settings, and error budget

NASA Astrophysics Data System (ADS)

Wang, Yang; Beirle, Steffen; Hendrick, Francois; Hilboll, Andreas; Jin, Junli; Kyuberis, Aleksandra A.; Lampel, Johannes; Li, Ang; Luo, Yuhan; Lodi, Lorenzo; Ma, Jianzhong; Navarro, Monica; Ortega, Ivan; Peters, Enno; Polyansky, Oleg L.; Remmers, Julia; Richter, Andreas; Puentedura, Olga; Van Roozendael, Michel; Seyler, André; Tennyson, Jonathan; Volkamer, Rainer; Xie, Pinhua; Zobov, Nikolai F.; Wagner, Thomas

2017-10-01

In order to promote the development of the passive DOAS technique the Multi Axis DOAS - Comparison campaign for Aerosols and Trace gases (MAD-CAT) was held at the Max Planck Institute for Chemistry in Mainz, Germany, from June to October 2013. Here, we systematically compare the differential slant column densities (dSCDs) of nitrous acid (HONO) derived from measurements of seven different instruments. We also compare the tropospheric difference of SCDs (delta SCD) of HONO, namely the difference of the SCDs for the non-zenith observations and the zenith observation of the same elevation sequence. Different research groups analysed the spectra from their own instruments using their individual fit software. All the fit errors of HONO dSCDs from the instruments with cooled large-size detectors are mostly in the range of 0.1 to 0.3 × 1015 molecules cm-2 for an integration time of 1 min. The fit error for the mini MAX-DOAS is around 0.7 × 1015 molecules cm-2. Although the HONO delta SCDs are normally smaller than 6 × 1015 molecules cm-2, consistent time series of HONO delta SCDs are retrieved from the measurements of different instruments. Both fits with a sequential Fraunhofer reference spectrum (FRS) and a daily noon FRS lead to similar consistency. Apart from the mini-MAX-DOAS, the systematic absolute differences of HONO delta SCDs between the instruments are smaller than 0.63 × 1015 molecules cm-2. The correlation coefficients are higher than 0.7 and the slopes of linear regressions deviate from unity by less than 16 % for the elevation angle of 1°. The correlations decrease with an increase in elevation angle. All the participants also analysed synthetic spectra using the same baseline DOAS settings to evaluate the systematic errors of HONO results from their respective fit programs. In general the errors are smaller than 0.3 × 1015 molecules cm-2, which is about half of the systematic difference between the real measurements.The differences of HONO delta SCDs retrieved in the selected three spectral ranges 335-361, 335-373 and 335-390 nm are considerable (up to 0.57 × 1015 molecules cm-2) for both real measurements and synthetic spectra. We performed sensitivity studies to quantify the dominant systematic error sources and to find a recommended DOAS setting in the three spectral ranges. The results show that water vapour absorption, temperature and wavelength dependence of O4 absorption, temperature dependence of Ring spectrum, and polynomial and intensity offset correction all together dominate the systematic errors. We recommend a fit range of 335-373 nm for HONO retrievals. In such fit range the overall systematic uncertainty is about 0.87 × 1015 molecules cm-2, much smaller than those in the other two ranges. The typical random uncertainty is estimated to be about 0.16 × 1015 molecules cm-2, which is only 25 % of the total systematic uncertainty for most of the instruments in the MAD-CAT campaign. In summary for most of the MAX-DOAS instruments for elevation angle below 5°, half daytime measurements (usually in the morning) of HONO delta SCD can be over the detection limit of 0.2 × 1015 molecules cm-2 with an uncertainty of ˜ 0.9 × 1015 molecules cm-2.

3 dimensional distributions of NO2, CHOCHO, and HCHO measured by the University of Colorado 2D-MAX-DOAS during MAD-CAT

NASA Astrophysics Data System (ADS)

Ortega, Ivan; Sinreich, Roman; Volkamer, Rainer

2014-05-01

We present results of 2 dimensional Multi Axis-DOAS (2D-MAX-DOAS) measurements to infer 3-dimensional measurements of trace gases by characterizing boundary layer vertical profiles and near surface azimuth horizontal distribution of NO2 (14 angles covering 360°). We combine the established optimal estimation inversion with a new parameterization approach; the first method to derive NO2 tropospheric vertical profiles and boundary layer height and the second one to retrieve the azimuth horizontal distribution of near surface NO2 mixing ratios, both at multiple wavelengths (350 nm, 450 nm, and 560 nm). This was conducted for three cloud-free days in the framework of the intensive Multi Axis DOAS Comparison campaign for Aerosols and Trace gases (MAD-CAT) in Mainz, Germany 2013. By retrieving NO2 at multiple wavelengths range-resolved distributions of NO2 are derived using an 'Onion-peeling' approach, i.e., exploiting the fact that the optical path lengths at different wavelengths probe different horizontal air masses. We also measure glyoxal (CHOCHO) and formaldehyde (HCHO) distributions, and present to our knowledge the first 3-dimesional trace-gas distribution measurements of CHOCHO by a ground-based instrument. We expand the 2D-MAX-DOAS capabilities to calculate azimuth ratios of HCHO-to-NO2 (RFN) and CHOCHO-to-NO2 (RGN) to pinpoint volatile organic compound (VOC) oxidation chemistry and CHOCHO-to-HCHO (RGF) ratios as an indicator of biogenic and/or anthropogenic VOC emissions. The results of RFN correlate well with RGN and we identify azimuth variations that indicate gradients in the VOC/NOx chemistry that leads to O3 and secondary aerosol production. While there is a clear diurnal pattern in the RFN and RGN, no such variations are observed in the RGF, which shows rather constant values below 0.04 throughout the day, consistent with previous measurements, and indicative of urban air masses.

Study of different operational modes of the IAP 2-port-DOAS instrument for atmospheric trace gases investigation during CINDI-2 campaign basing on residual noise analysis

NASA Astrophysics Data System (ADS)

Borovski, A.; Postylyakov, O.; Elokhov, A.; Bruchkovski, I.

2017-11-01

An instrument for measuring atmospheric trace gases by DOAS method using scattered solar radiation was developed in A.M.Obukhov IAP RAS. The instrument layout is based on the lab Shamrock 303i spectrograph supplemented by 2-port radiation input system employing optical fiber. Optical ports may be used with a telescope with fixed field of view or with a scanning MAX-DOAS unit. MAX-DOAS unit port will be used for investigation of gas contents and profiles in the low troposphere. In September 2016 the IAP instrument participated in the CINDI-2 campaign, held in the Netherlands. CINDI 2 (2nd Cabauw Intercomparison of Nitrogen Dioxide Measuring Instruments) involves about 40 instruments quasi-synchronously performing DOAS measurements of NO2 and other trace gases. During the campaign the instrument ports had telescopes A and B with similar field of view of about 0.3°. Telescope A was always directed to the zenith. Telescope B was directed at 5° elevation angle. Two gratings were installed in the spectrometer. They provide different spectral resolution (FWHM 0.4 and 0.8 nm respectively) and spectral window width ( 70 and 140 nm respectively). During CINDI-2 campaign we performed test measurements in UV and visible wavelength ranges to investigate instrument stability and retrieval errors of NO2 and HCHO contents. We perform the preliminary error analysis of retrieval of the NO2 and HCHO differential slant column densities using spectra measured in four modes of the instrument basing on residual noise analysis in this paper. It was found that rotation of grating turret does not significantly affected on quality of NO2 DSCD retrieval from spectra which measured in visible spectral region. Influence of grating turret rotation is much more significant for gas DSCD retrieval from spectra which measured in UV spectral region. Standard deviation of retrieval error points to presence of some systematic error.

Radiological-Pathological Correlations Following Blast-Related Traumatic Brain Injury in the Whole Human Brain Using ex Vivo Diffusion Tensor Imaging

DTIC Science & Technology

2014-01-01

were as follows: Blast TBI: Suicide drug overdose – blast years prior Ruptured aneurysm – blast years prior intraventricular hemorrhage...drug overdose Suicide blunt trauma - fall Cancer Cardiac Arrest Tissue fixation was highly variable because cases were obtained from 4 different...blast years prior Civilian Blast DOA Non-blast TBI: MVA – DOA MVA – DOS Suicide – NFL – GSW to chest Cardiac Arrest – NFL Controls: Suicide

Evaluation of Variable Refrigerant Flow Systems Performance on Oak Ridge National Laboratory s Flexible Research Platform: Part 2 Heating Season Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Im, Piljae; Malhotra, Mini; Munk, Jeffrey D.

The performance of two HVAC systems was evaluated using ORNL’s FRP, which is a two-story, 3,200 ft2 (297.3 m2) multi-zone unoccupied building that represents a typical low-rise, small office building common in the US existing building stock. The FRP is equipped with a conventional 12.5 ton (44 kW) RTU-VAV reheat system as the baseline system. For this study, a 12 ton (42 kW) VRF with a dedicated outdoor air system (DOAS) was installed to be compared with the baseline RTU system.

Thailandins A and B, New Polyene Macrolactone Compounds Isolated from Actinokineospora bangkokensis Strain 44EHW(T), Possessing Antifungal Activity against Anthracnose Fungi and Pathogenic Yeasts.

PubMed

Intra, Bungonsiri; Greule, Anja; Bechthold, Andreas; Euanorasetr, Jirayut; Paululat, Thomas; Panbangred, Watanalai

2016-06-29

Two new polyene macrolactone antibiotics, thailandins A, 1, and B, 2, were isolated from the fermentation broth of rhizosphere soil-associated Actinokineospora bangkokensis strain 44EHW(T). The new compounds from this strain were purified using semipreparative HPLC and Sephadex LH-20 gel filtration while following an antifungal activity guided fractionation. Their structures were elucidated through spectroscopic techniques including UV, HR-ESI-MS, and NMR. These compounds demonstrated broad spectrum antifungal activity against fungi causing anthracnose disease (Colletotrichum gloeosporioides DoA d0762, Colletotrichum gloeosporiodes DoA c1060, and Colletotrichum capsici DoA c1511) as well as pathogenic yeasts (Candida albicans MT 2013/1, Candida parasilopsis DKMU 434, and Cryptococcus neoformans MT 2013/2) with minimum inhibitory concentrations ranging between 16 and 32 μg/mL. This is the first report of polyene antibiotics produced by Actinokineospora species as bioactive compounds against anthracnose fungi and pathogenic yeast strains.

Wideband Direction of Arrival Estimation in the Presence of Unknown Mutual Coupling

PubMed Central

Li, Weixing; Zhang, Yue; Lin, Jianzhi; Guo, Rui; Chen, Zengping

2017-01-01

This paper investigates a subarray based algorithm for direction of arrival (DOA) estimation of wideband uniform linear array (ULA), under the presence of frequency-dependent mutual coupling effects. Based on the Toeplitz structure of mutual coupling matrices, the whole array is divided into the middle subarray and the auxiliary subarray. Then two-sided correlation transformation is applied to the correlation matrix of the middle subarray instead of the whole array. In this way, the mutual coupling effects can be eliminated. Finally, the multiple signal classification (MUSIC) method is utilized to derive the DOAs. For the condition when the blind angles exist, we refine DOA estimation by using a simple approach based on the frequency-dependent mutual coupling matrixes (MCMs). The proposed method can achieve high estimation accuracy without any calibration sources. It has a low computational complexity because iterative processing is not required. Simulation results validate the effectiveness and feasibility of the proposed algorithm. PMID:28178177

On the angular error of intensity vector based direction of arrival estimation in reverberant sound fields.

PubMed

Levin, Dovid; Habets, Emanuël A P; Gannot, Sharon

2010-10-01

An acoustic vector sensor provides measurements of both the pressure and particle velocity of a sound field in which it is placed. These measurements are vectorial in nature and can be used for the purpose of source localization. A straightforward approach towards determining the direction of arrival (DOA) utilizes the acoustic intensity vector, which is the product of pressure and particle velocity. The accuracy of an intensity vector based DOA estimator in the presence of noise has been analyzed previously. In this paper, the effects of reverberation upon the accuracy of such a DOA estimator are examined. It is shown that particular realizations of reverberation differ from an ideal isotropically diffuse field, and induce an estimation bias which is dependent upon the room impulse responses (RIRs). The limited knowledge available pertaining the RIRs is expressed statistically by employing the diffuse qualities of reverberation to extend Polack's statistical RIR model. Expressions for evaluating the typical bias magnitude as well as its probability distribution are derived.

MAX-DOAS observations from ground, ship, and research aircraft: maximizing signal-to-noise to measure 'weak' absorbers

NASA Astrophysics Data System (ADS)

Volkamer, Rainer; Coburn, Sean; Dix, Barbara; Sinreich, Roman

2009-08-01

Multi AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instruments, as solar straylight satellites, require an accurate characterization and elimination of Fraunhofer lines from solar straylight spectra to measure the atmospheric column abundance of reactive gases that destroy toxic and heat trapping ozone and form climate cooling aerosols, like glyoxal (CHOCHO), iodine oxide (IO), or bromine oxide (BrO). The currently achievable noise levels with state-of-the-art DOAS instruments are limited to δ'DL ~ 10-4 (noise equivalent differential optical density, δ') further noise reductions are typically not straightforward, and the reason for this barrier is not well understood. Here we demonstrate that the nonlinearity of state-of-the-art CCD detectors poses a limitation to accurately characterize Fraunhofer lines; the incomplete elimination of Fraunhofer lines is found to cause residual structures of δ' ~ 10-4, and only partially accounted by fitting of an "offset" spectrum. We have developed a novel software tool, the CU Data Acquisition Code that overcomes this barrier by actively controlling the CCD saturation level, and demonstrates that δ'DL on the order of 10-5 are possible without apparent limitations from the presence of Fraunhofer lines. The software also implements active control of the elevation angle (angle with respect to the horizon) by means of a Motion Compensation System for use with mobile MAX-DOAS deployments from ships and aircraft. Finally, a novel approach to convert slant column densities into line-of-sight averaged concentrations is discussed.

Retrieval of CHOCHO from MAX-DOAS measurements in the Beijing area

NASA Astrophysics Data System (ADS)

Hendrick, Francois; Lerot, Christophe; Stavrakou, Trissevgeni; De Smedt, Isabelle; Fayt, Caroline; Gielen, Clio; Hermans, Christian; Müller, Jean-Francois; Pinardi, Gaia; Van Roozendael, Michel

2015-04-01

Glyoxal (CHOCHO) is one of the most important carbonyl compounds in the atmosphere. It is produced mainly by the oxidation of biogenic and anthropogenic non-methane volatile organic compounds (NMVOCs) which participate to the formation of tropospheric ozone and secondary organic aerosols. CHOCHO is also directly released by biomass burning and fossil fuel combustion. Measuring this species is therefore of major importance for air quality monitoring, especially given the scarcity of available CHOCHO observational data sets. In this presentation, CHOCHO vertical profiles and corresponding column densities are retrieved from MAX-DOAS measurements in the Beijing city center and at the suburban site of Xianghe located at 60km East of Beijing. The periods covered by the observations are June 2008-April 2009 in Beijing and March 2010-December 2014 in Xianghe. We first investigate the capability of the MAX-DOAS technique to measure this species in such highly-polluted environment. Then the diurnal and seasonal cycles of CHOCHO near-surface concentrations and vertical column densities as well as the corresponding CHOCHO/HCHO ratios are examined on a long-term basis at both locations. The CHOCHO/HCHO ratios are derived from MAX-DOAS HCHO vertical profiles retrieved in parallel to the CHOCHO profiles. These diurnal and seasonal cycles are further assessed using simulations from the 3D-CTM IMAGES and observations from the OMI and GOME-2 satellite nadir instruments. The impact of these results on our knowledge about the CHOCHO budget is discussed.

Is there a Developed Oldowan A at Olduvai Gorge? A diachronic analysis of the Oldowan in Bed I and Lower-Middle Bed II at Olduvai Gorge, Tanzania.

PubMed

Proffitt, Tomos

2018-05-08

Debates regarding the validity of the Developed Oldowan as separate cultural facies within the Oldowan techno-complex have primarily concentrated on the Developed Oldowan B/Acheulean transition, with little attention paid to the validity of the Developed Oldowan A (DOA) as a valid technological differentiation. This study presents a diachronic technological analysis and comparison of Oldowan and DOA lithic assemblages from Olduvai Gorge, Tanzania, dated between 1.84 and 1.6 Ma, to test the validity of Leakey's original distinction between these two cultural facies. The results from this comparative analysis show very few technological differences between the lithic assemblages previously assigned to the DOA and Classic Oldowan. Significant diachronic variation in raw material availability and use is, however, identified between Bed I and Lower/Middle Bed II of Olduvai Gorge, which may go some way to explaining the originally perceived techno-cultural differences. The results suggest an increase in hominin knapping and percussive activities, as well as a clear ability to preferentially select high quality raw materials stratigraphically above Tuff IF. Technological innovation and complexity, however, does not seem to vary significantly between the Classic Oldowan and DOA assemblages. The results of this analysis along with similar studies from the wider eastern African region lead to the conclusion that the term Developed Oldowan A should no longer be used. Copyright © 2018 Elsevier Ltd. All rights reserved.

Direction-of-arrival estimation for co-located multiple-input multiple-output radar using structural sparsity Bayesian learning

NASA Astrophysics Data System (ADS)

Wen, Fang-Qing; Zhang, Gong; Ben, De

2015-11-01

This paper addresses the direction of arrival (DOA) estimation problem for the co-located multiple-input multiple-output (MIMO) radar with random arrays. The spatially distributed sparsity of the targets in the background makes compressive sensing (CS) desirable for DOA estimation. A spatial CS framework is presented, which links the DOA estimation problem to support recovery from a known over-complete dictionary. A modified statistical model is developed to accurately represent the intra-block correlation of the received signal. A structural sparsity Bayesian learning algorithm is proposed for the sparse recovery problem. The proposed algorithm, which exploits intra-signal correlation, is capable being applied to limited data support and low signal-to-noise ratio (SNR) scene. Furthermore, the proposed algorithm has less computation load compared to the classical Bayesian algorithm. Simulation results show that the proposed algorithm has a more accurate DOA estimation than the traditional multiple signal classification (MUSIC) algorithm and other CS recovery algorithms. Project supported by the National Natural Science Foundation of China (Grant Nos. 61071163, 61271327, and 61471191), the Funding for Outstanding Doctoral Dissertation in Nanjing University of Aeronautics and Astronautics, China (Grant No. BCXJ14-08), the Funding of Innovation Program for Graduate Education of Jiangsu Province, China (Grant No. KYLX 0277), the Fundamental Research Funds for the Central Universities, China (Grant No. 3082015NP2015504), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PADA), China.

GMTI Direction of Arrival Measurements from Multiple Phase Centers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doerry, Armin W.; Bickel, Douglas L.

2015-03-01

Ground Moving Target Indicator (GMTI) radar attempts to detect and locate targets with unknown motion. Very slow-moving targets are difficult to locate in the presence of surrounding clutter. This necessitates multiple antenna phase centers (or equivalent) to offer independent Direction of Arrival (DOA) measurements. DOA accuracy and precision generally remains dependent on target Signal-to-Noise Ratio (SNR), Clutter-toNoise Ratio (CNR), scene topography, interfering signals, and a number of antenna parameters. This is true even for adaptive techniques like Space-Time-AdaptiveProcessing (STAP) algorithms.

Determination of the NO2 concentration and its distribution with different DOAS techniques - a study in the metropolitan area of Hong Kong

NASA Astrophysics Data System (ADS)

Horbanski, M.; Chan, K. L.; Pöhler, D.; Wenig, M. O.; Platt, U.

2012-04-01

In Hong Kong, like in other urban areas, nitrogen dioxide (NO2) emissions still remain one of the most problematic pollutions. Even though a lot of effort has already been made towards their reduction, concentrations are often much above the recommended limits. Therefore, the Hong Kong Environmental Protection Department continuously monitors the NO2 concentration levels. These stations only give in-situ information at a few fixed locations, which are unable to capture the strong spatial gradients that are present in urban areas. These gradients are mainly caused by differences in automobile traffic, the population densities and industries that are found in the individual city areas. The gradients are further enhanced by street canyon effects. Hence, it can be assumed that there are areas with much higher pollution compared to the values at the official measuring sites. At present the uncertainties about the spatial NO2 distribution place a limitation on the assessment of health risks and on the quality of chemical model calculations. We applied a new Cavity Enhanced (CE-) DOAS instrument to car based measurements in the city of Hong Kong for eight days in December 2010. Measurements on mobile platforms like cars give the opportunity to create a map of the NO2 for a whole city area with high spatial resolution. The CE-DOAS instrument is distinguished by its compact and robust setup. It directly measures NO2 by its optical absorption and therefore it does not have interferences with other trace gas species like O3 or NOy. This is a great advantage over other NO2 instruments (e.g. solid state detectors or chemiluminescence instruments which have such known problems). For our measurements a van travels along carefully selected tracks to give a representative coverage of the area of interest. The mobile measurements are corrected for the varying meteorological conditions and traffic variations during the different measurements by comparing them to a fixed measurement of NO2 to derive a representative distribution map. This is done by a simultaneously performed Long Path DOAS measurement which gives the average NO2 concentration along a few kilometer long light path over the area of interest. Our measurements show that NO2 concentrations in Hong Kong vary by more than an order of magnitude on scales of only few 100m. Concentrations up to several ppmv are observed at various locations, clearly showing that environmental measurement stations with their fixed point measurements do not sufficiently capture these variations and the given results may not be correct for a location close by. Besides the determination of NO2 maps the Long Path DOAS measurements since December 2009 are used to validate DOAS based OMI satellite measurements. This is done to assess the usability of satellite based measurements for air quality monitoring in urban areas. Monthly averaged LP-DOAS and OMI measurements correlate well but the satellite measurements significantly underestimate the NO2 concentration. Furthermore, the mean weekly NO2 cycles, display different characteristics which will be discussed.

Retrieval of vertical aerosol- and trace gas profiles in the Antarctic troposphere using helicopter-borne MAX-DOAS measurements

NASA Astrophysics Data System (ADS)

Nasse, Jan-Marcus; Zielcke, Johannes; Buxmann, Joelle; Frieß, Udo; Platt, Ulrich

2014-05-01

During springtime in polar regions when the sunlight returns, bromine monoxide (BrO) is released from sea ice into the atmosphere from saline surfaces due to an autocatalytic reaction mechanism. BrO affects the oxidative properties of the troposphere and can lead to a virtually complete depletion of surface ozone within a few days or even hours. Furthermore, the oxidation of gaseous elemental mercury by BrO renders this toxic compound soluble and leads to a deposition and thus entry of mercury into the vulnerable biosphere. However, the exact nature of the bromine radical sources in polar regions, as well as the details of the mechanisms leading to bromine explosions and also the interactions between dynamics and chemistry are not yet completely understood. For a better understanding of these processes, an accurate determination of the spatio-temporal distribution of BrO is crucial. We present first measurements of BrO and aerosols performed onboard a helicopter using a compact Multi AXial Differential Absorption Spectroscopy (MAX-DOAS) instrument during a cruise of the German research vessel Polarstern in the Antarctic Weddell Sea between August and October 2013. Numerous flights were performed in the boundary layer as well as in the free troposphere up to 2300m. Due to its versatility, allowing measurements at multiple altitudes with small elevation angles and thus high air mass factors, a helicopter as a platform for MAX-DOAS measurements offers a considerably improved information content throughout the lower troposphere compared to MAX-DOAS measurements from the ground. Using our HEIPRO (HEIdelberg Profile) retrieval algorithm based on optimal estimation, vertical profiles of aerosols and trace gases can be retrieved with an unprecedented vertical resolution and a better sensitivity for higher altitudes. Furthermore, these measurements allow for a thorough characterization of the dynamical and chemical processes bromine radicals are involved in. We will present BrO and aerosol vertical profiles obtained from the helicopter-borne observations, discuss the vertical resolution, error budget and information content of the measurements, and compare the data with profiles from our co-located ship-borne MAX-DOAS instrument.

First results of the CINDI-2 semi-blind MAX-DOAS intercomparison

NASA Astrophysics Data System (ADS)

Kreher, Karin; van Roozendael, Michel; Hendrick, Francois; Apituley, Arnoud; Friess, Udo; Lampel, Johannes; Piters, Ankie; Richter, Andreas; Wagner, Thomas; Cindi-2 Participants, All

2017-04-01

The second Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI-2) took place at the Cabauw Experimental Site for Atmospheric Research (CESAR; Utrecht area, The Netherlands) from 25 August until 7 October 2016. The goals of this inter-comparison campaign are to support the creation of high-quality ground-based data sets (e.g. to provide reliable long-term time series for trend analysis and satellite data validation), to characterise and better understand the differences between a large number of MAX-DOAS and DOAS instruments and analysis methods, and to contribute to a harmonisation of the measurement settings and retrieval methods. During a time period of 17 days, from 12 to 28 September 2016, a formal semi-blind intercomparison was held following a detailed measurement protocol. The development of this protocol was based on the experience gained during the first CINDI campaign held in 2009 as well as more recent projects and campaigns such as the MADCAT campaign in Mainz, Germany, in 2013. Strong emphasis was put on the careful synchronisation of the measurement sequence and on exact alignment of the elevation angles using horizon scans and lamp measurements. In this presentation, we provide an overview and some highlights of the MAX-DOAS semi-blind intercomparison campaign. We will introduce the participating groups, their instruments and the measurement protocol details, and then summarize the campaign outcomes to date. The CINDI-2 data sets have been investigated using a range of diagnostics including comparisons of daily time series and relative differences between the data sets, regression analysis and correlation plots. The data products so far investigated are NO2 (nitrogen dioxide) in the UV and visible wavelength region, O4 (oxygen dimer) in the same two wavelength intervals, O3 (ozone) in the UV and visible wavelength region, HCHO (formaldehyde) and NO2 in an additional (smaller) wavelength range in the visible. The results based on the regression analysis are presented in summary plots and tables, addressing MAX-DOAS and twilight zenith sky measurements separately. Further information on instrumental details such as the alignment of the viewing direction and elevation and the field of view are also summarized and included in the overall interpretation.

Investigation of the 3D distribution of tropospheric formaldehyde (HCHO) at the city of Mainz (Germany) using measurements of a 4 azimuth MAX-DOAS instrument

NASA Astrophysics Data System (ADS)

Donner, Sebastian; Gu, Myojeong; Remmers, Julia; Wang, Yang; Wagner, Thomas

2017-04-01

The Differential Optical Absorption Spectroscopy (DOAS)-method allows to investigate the distribution of different atmospheric trace gases (e.g. NO2, SO2, HCHO...) simultaneously. This is done by analysing the absorptions of these species in spectra of scattered sunlight. Multi-AXis (MAX)-DOAS measurements observe scattered sun light under different elevation angles. From such measurements tropospheric vertical column densities (VCDs) and vertical profiles of the measured trace gases and aerosols can be determined. We performed measurements using a 4 azimuth MAX-DOAS system on the roof of the Max Planck Institute for Chemistry in Mainz/Germany since 2013. This instrument observes scattered sunlight in 4 separate orthogonal azimuth directions. We derive vertical profiles of trace gases in these 4 different azimuth directions. From these results we can investigate the 3D distribution of the trace gases. Mainz is located at the edge of the Rhine-Main area which is one of the densest populated areas in Germany. Therefore it experiences episodes of high and low pollution depending on the meteorological conditions. In this study we focus on formaldehyde (HCHO). It is either emitted directly by industries and other anthropogenic and biogenic activities. Usually higher amounts are produced by photochemical reactions from precursor substances (secondary production), where it plays an important role in photochemical smog chemistry and O3 chemistry. As it is an intermediate product of basic oxidation cycles of other hydrocarbons (also referred to as volatile organic compounds (VOCs)) especially in summer its concentrations are determined by the abundances of VOCs. Therefore HCHO observations can be used as an indicator for VOCs. Up to now we have nearly 4 years (starting from May 2013) of almost continuous data which provides already a quite large dataset. In this work we present a first overview of our HCHO results including time series of HCHO columns, a first comparison of the results for different azimuth directions, a first characterisation of the corresponding spatial gradients and a comparison to mobile MAX-DOAS measurements which were performed in Winter 2015/2016.

Treatment strategies for inherited optic neuropathies: past, present and future

PubMed Central

Yu-Wai-Man, P; Votruba, M; Moore, A T; Chinnery, P F

2014-01-01

Bilateral visual loss secondary to inherited optic neuropathies is an important cause of registrable blindness among children and young adults. The two prototypal disorders seen in clinical practice are Leber hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (DOA). About 90% of LHON cases are due to one of three mitochondrial DNA (mtDNA) point mutations: m.3460G>A, m.11778G>A, and m.14484T>C, which affect critical complex I subunits of the mitochondrial respiratory chain. The majority of patients with DOA harbour pathogenic mutations within OPA1, a nuclear gene that codes for a multifunctional inner mitochondrial membrane protein. Despite their contrasting genetic basis, LHON and DOA share overlapping pathological and clinical features that serve to highlight the striking tissue-specific vulnerability of the retinal ganglion cell (RGC) layer to disturbed mitochondrial function. In addition to severe visual loss secondary to progressive optic nerve degeneration, a subgroup of patients will also develop a more aggressive syndromic phenotype marked by significant neurological deficits. The management of LHON and DOA remains largely supportive, but major advances in our understanding of the mechanisms underpinning RGC loss in these two disorders are paving the way for novel forms of treatment aimed at halting or reversing visual deterioration at different stages of the disease process. In addition to neuroprotective strategies for rescuing RGCs from irreversible cell death, innovative in vitro fertilisation techniques are providing the tantalising prospect of preventing the germline transmission of pathogenic mtDNA mutations, eradicating in so doing the risk of disease in future generations. PMID:24603424

Direction of Arrival Measurements of Auroral Medium Frequency Burst Radio Emissions at Toolik Lake, AK

NASA Astrophysics Data System (ADS)

Bunch, N. L.; Labelle, J. W.; Hughes, J. M.; Weatherwax, A. T.; Ye, S.; Lummerzheim, D.

2007-12-01

MF burst is an impulsive radio emission of auroral origin detected by ground-based instruments approximately between 1,300 and 3,700 kHz, and associated with substorm onsets. Its exact generation mechanism is unknown, though it has been speculated that it arises from mode conversion radiation. To discover the generation mechanism and the relation of MF burst to auroral processes, Dartmouth has deployed radio interferometers in Alaska, Northern Canada, Greenland, and Antarctica, including a three-element interferometer deployed at Toolik Lake Field Station in Alaska in 2006. This instrument measured spectra, amplitudes, and directions of arrival (DOA's) of over 47 MF burst events occurring between November 30, 2006 and May 26, 2007. These represent the first DOA measurements ever reported for the impulsive MF burst phenomenon. Preliminary analysis shows that the events originated from a wide range of directions in the sky, with all azimuths represented in the distribution of DOA's. The DOA of each individual event is well-defined, however. Many events show apparent motion, with southward motions more common than northward among the subset of events analyzed so far. Some of the events were detected simultaneously on an interferometer deployed at Kaktovik, Alaska, 400 km away. The all-sky imager at Toolik Lake was also operational for some events. Further analysis of these data promises to reveal first information about the locations and motions of MF burst sources, a first step towards discovering the generation mechanism of this mysterious radio emission and its relation to auroral processes.

Winter Distribution of On-road NO2 Concentration in Hong Kong

NASA Astrophysics Data System (ADS)

Zhu, Y.; Chan, K. L.; Boll, J.; Schütt, A. M. N.; Lipkowitsch, I.; Wenig, M.

2017-12-01

In this study, we investigated the spatial distribution of on road NO2 concentration using Cavity-Enhanced Differential Optical Absorption Spectroscopy (DOAS). We performed two measurement campaigns in winter 2010 and 2017. Air pollution is a severe problem for many big cities, especially in Asia. Traffic emission is the primary source of urban pollutants. As Hong Kong is one of the most densely populated cities in the world, many inhabitants are exposed to accumulated pollutants in street canyons. Our mobile measurements were performed for a week in December, 2010 and March, 2017. Additionally, long term air pollution data measured by a long-path DOAS (LP-DOAS) and the Environment Protection Department (EPD) air quality monitoring network were used to investigate the long term trend and seasonal variations of atmospheric NO2 in Hong Kong.The experiment setup and preliminary results of mobile measurements are presented. The measurements were performed along a fixed route which covers most of the urban area. We assembled a NO2 concentration map 2 to 3 times per day in order to cover both morning and evening rush hours. In order to construct a consistent map, we use coinciding LP-DOAS NO2 data to correct for the diurnal cycle. Furthermore, the spatial and temporal distribution of NO2 changes with the day of the week. Traffic load is highly dependent on human activities which typically fall into a 7 days cycle. Therefore, we have analyzed the weekly pattern of on road NO2 distribution to see the differences between anthropogenic emissions during weekdays and weekend.

Robust Angle Estimation for MIMO Radar with the Coexistence of Mutual Coupling and Colored Noise.

PubMed

Wang, Junxiang; Wang, Xianpeng; Xu, Dingjie; Bi, Guoan

2018-03-09

This paper deals with joint estimation of direction-of-departure (DOD) and direction-of- arrival (DOA) in bistatic multiple-input multiple-output (MIMO) radar with the coexistence of unknown mutual coupling and spatial colored noise by developing a novel robust covariance tensor-based angle estimation method. In the proposed method, a third-order tensor is firstly formulated for capturing the multidimensional nature of the received data. Then taking advantage of the temporal uncorrelated characteristic of colored noise and the banded complex symmetric Toeplitz structure of the mutual coupling matrices, a novel fourth-order covariance tensor is constructed for eliminating the influence of both spatial colored noise and mutual coupling. After a robust signal subspace estimation is obtained by using the higher-order singular value decomposition (HOSVD) technique, the rotational invariance technique is applied to achieve the DODs and DOAs. Compared with the existing HOSVD-based subspace methods, the proposed method can provide superior angle estimation performance and automatically jointly perform the DODs and DOAs. Results from numerical experiments are presented to verify the effectiveness of the proposed method.

Sequential Poly-ubiquitylation by Specialized Conjugating Enzymes Expands the Versatility of a Quality Control Ubiquitin Ligase.

PubMed

Weber, Annika; Cohen, Itamar; Popp, Oliver; Dittmar, Gunnar; Reiss, Yuval; Sommer, Thomas; Ravid, Tommer; Jarosch, Ernst

2016-09-01

The Doa10 quality control ubiquitin (Ub) ligase labels proteins with uniform lysine 48-linked poly-Ub (K48-pUB) chains for proteasomal degradation. Processing of Doa10 substrates requires the activity of two Ub conjugating enzymes. Here we show that the non-canonical conjugating enzyme Ubc6 attaches single Ub molecules not only to lysines but also to hydroxylated amino acids. These Ub moieties serve as primers for subsequent poly-ubiquitylation by Ubc7. We propose that the evolutionary conserved propensity of Ubc6 to mount Ub on diverse amino acids augments the number of ubiquitylation sites within a substrate and thereby increases the target range of Doa10. Our work provides new insights on how the consecutive activity of two specialized conjugating enzymes facilitates the attachment of poly-Ub to very heterogeneous client molecules. Such stepwise ubiquitylation reactions most likely represent a more general cellular phenomenon that extends the versatility yet sustains the specificity of the Ub conjugation system. Copyright © 2016 Elsevier Inc. All rights reserved.

MAX-DOAS measurements of nitrogen dioxide at the high altitude sites Zugspitze (2964 m) and Pico Espejo (4765 m)

NASA Astrophysics Data System (ADS)

Schreier, Stefan F.; Richter, Andreas; Wittrock, Folkard; Burrows, John P.

2015-04-01

Spectral measurements at two mountain sites were performed with a MAX-DOAS (Multi AXis Differential Optical Absorption Spectroscopy) instrument from February to July 2003 (Zugspitze, Germany) and from March 2004 to November 2008 (Pico Espejo, Venezuela). Here, these measurements are used for the retrieval of slant column densities (SCDs) of nitrogen dioxide (NO2). While at the altitude of observations the NO2 levels are usually small, uplifting of anthropogenic emissions from the valley and in Venezuela also transport of emissions from biomass burning can lead to significant enhancements. Daily, weekly, and seasonal cycles of NO2 SCDs are shown for the two stations, linked to different meteorological conditions and compared between the two sites. In a next step, a preliminary approach to derive vertical column densities (VCDs) is presented. VCDs of NO2 from ground-based MAX-DOAS instruments provide useful information for the validation of satellite instruments such as SCIAMACHY, OMI, and GOME-2. Comparisons between ground-based and satellite-based NO2 VCDs are shown for selected periods.

Robust Angle Estimation for MIMO Radar with the Coexistence of Mutual Coupling and Colored Noise

PubMed Central

Wang, Junxiang; Wang, Xianpeng; Xu, Dingjie; Bi, Guoan

2018-01-01

This paper deals with joint estimation of direction-of-departure (DOD) and direction-of- arrival (DOA) in bistatic multiple-input multiple-output (MIMO) radar with the coexistence of unknown mutual coupling and spatial colored noise by developing a novel robust covariance tensor-based angle estimation method. In the proposed method, a third-order tensor is firstly formulated for capturing the multidimensional nature of the received data. Then taking advantage of the temporal uncorrelated characteristic of colored noise and the banded complex symmetric Toeplitz structure of the mutual coupling matrices, a novel fourth-order covariance tensor is constructed for eliminating the influence of both spatial colored noise and mutual coupling. After a robust signal subspace estimation is obtained by using the higher-order singular value decomposition (HOSVD) technique, the rotational invariance technique is applied to achieve the DODs and DOAs. Compared with the existing HOSVD-based subspace methods, the proposed method can provide superior angle estimation performance and automatically jointly perform the DODs and DOAs. Results from numerical experiments are presented to verify the effectiveness of the proposed method. PMID:29522499

Vertical columns of NO2, HONO, HCHO, CHOCHO and aerosol extinction: diurnal and seasonal variations in context of CalNex and CARES

NASA Astrophysics Data System (ADS)

Ortega, I.; Coburn, S.; Oetjen, H.; Sinreich, R.; Thalman, R. M.; Waxman, E.; Volkamer, R.

2011-12-01

We present results from two ground-based University of Colorado Multi Axis Differential Optical Absorption Spectroscopy (CU-MAX-DOAS) instruments that were deployed during the CALNEX and CARES 2010 field campaigns. Ground based CU-MAX-DOAS measurements were carried out through Dec 2010, and measured vertical column abundances of nitrogen dioxide (NO2), nitrous acid (HONO), formaldehyde (HCHO), glyoxal (CHOCHO), and aerosol extinction, which is determined indirectly from observing the oxygen dimers (O4). The measurements were acquired on the top of Millikan library at Caltech, Pasadena, CA, at the Fontana Arrows site located 60 Km east of Caltech, and for a limited period also downwind of Sacramento at T1 site during CARES. In the South Coast Air Basin, the MAX-DOAS instruments at both sites collected an extended time series of use to test satellites, and atmospheric chemistry models. We determine the state of the planetary boundary layer by comparing the columns observations with in-situ sensors, and place the CALNEX and CARES measurements intensive into seasonal context.

Covariance-based direction-of-arrival estimation of wideband coherent chirp signals via sparse representation.

PubMed

Sha, Zhichao; Liu, Zhengmeng; Huang, Zhitao; Zhou, Yiyu

2013-08-29

This paper addresses the problem of direction-of-arrival (DOA) estimation of multiple wideband coherent chirp signals, and a new method is proposed. The new method is based on signal component analysis of the array output covariance, instead of the complicated time-frequency analysis used in previous literatures, and thus is more compact and effectively avoids possible signal energy loss during the hyper-processes. Moreover, the a priori information of signal number is no longer a necessity for DOA estimation in the new method. Simulation results demonstrate the performance superiority of the new method over previous ones.

Ozone distributions over southern Lake Michigan: comparisons between ferry-based observations, shoreline-based DOAS observations and model forecasts

NASA Astrophysics Data System (ADS)

Cleary, P. A.; Fuhrman, N.; Schulz, L.; Schafer, J.; Fillingham, J.; Bootsma, H.; McQueen, J.; Tang, Y.; Langel, T.; McKeen, S.; Williams, E. J.; Brown, S. S.

2015-05-01

Air quality forecast models typically predict large summertime ozone abundances over water relative to land in the Great Lakes region. While each state bordering Lake Michigan has dedicated monitoring systems, offshore measurements have been sparse, mainly executed through specific short-term campaigns. This study examines ozone abundances over Lake Michigan as measured on the Lake Express ferry, by shoreline differential optical absorption spectroscopy (DOAS) observations in southeastern Wisconsin and as predicted by the Community Multiscale Air Quality (CMAQ) model. From 2008 to 2009 measurements of O3, SO2, NO2 and formaldehyde were made in the summertime by DOAS at a shoreline site in Kenosha, WI. From 2008 to 2010 measurements of ambient ozone were conducted on the Lake Express, a high-speed ferry that travels between Milwaukee, WI, and Muskegon, MI, up to six times daily from spring to fall. Ferry ozone observations over Lake Michigan were an average of 3.8 ppb higher than those measured at shoreline in Kenosha, with little dependence on position of the ferry or temperature and with greatest differences during evening and night. Concurrent 1-48 h forecasts from the CMAQ model in the upper Midwestern region surrounding Lake Michigan were compared to ferry ozone measurements, shoreline DOAS measurements and Environmental Protection Agency (EPA) station measurements. The bias of the model O3 forecast was computed and evaluated with respect to ferry-based measurements. Trends in the bias with respect to location and time of day were explored showing non-uniformity in model bias over the lake. Model ozone bias was consistently high over the lake in comparison to land-based measurements, with highest biases for 25-48 h after initialization.

MAX-DOAS tropospheric nitrogen dioxide column measurements compared with the Lotos-Euros air quality model

NASA Astrophysics Data System (ADS)

Vlemmix, T.; Eskes, H. J.; Piters, A. J. M.; Schaap, M.; Sauter, F. J.; Kelder, H.; Levelt, P. F.

2015-02-01

A 14-month data set of MAX-DOAS (Multi-Axis Differential Optical Absorption Spectroscopy) tropospheric NO2 column observations in De Bilt, the Netherlands, has been compared with the regional air quality model Lotos-Euros. The model was run on a 7×7 km2 grid, the same resolution as the emission inventory used. A study was performed to assess the effect of clouds on the retrieval accuracy of the MAX-DOAS observations. Good agreement was found between modeled and measured tropospheric NO2 columns, with an average difference of less than 1% of the average tropospheric column (14.5 · 1015 molec cm-2). The comparisons show little cloud cover dependence after cloud corrections for which ceilometer data were used. Hourly differences between observations and model show a Gaussian behavior with a standard deviation (σ) of 5.5 · 1015 molec cm-2. For daily averages of tropospheric NO2 columns, a correlation of 0.72 was found for all observations, and 0.79 for cloud free conditions. The measured and modeled tropospheric NO2 columns have an almost identical distribution over the wind direction. A significant difference between model and measurements was found for the average weekly cycle, which shows a much stronger decrease during the weekend for the observations; for the diurnal cycle, the observed range is about twice as large as the modeled range. The results of the comparison demonstrate that averaged over a long time period, the tropospheric NO2 column observations are representative for a large spatial area despite the fact that they were obtained in an urban region. This makes the MAX-DOAS technique especially suitable for validation of satellite observations and air quality models in urban regions.

Estimations of pollution emissions by the Moscow megapolis basing on in-situ measurements and optical remote sensing

NASA Astrophysics Data System (ADS)

Elansky, N.; Postylyakov, O.; Verevkin, Y.; Volobuev, L.; Ponomarev, N.

2017-11-01

By the present a large amount of data has been accumulated on direct measurements of the pollution and thermodynamic state of the atmosphere in the Moscow region, which was obtained at stations of Roshydromet, Mosecomonitoring, A.M.Obukhov Institute of Atmospheric Physics (OIAP), M.V. Lomonosov Moscow State University, NPO Typhoon, what allows estimating pollution emissions based on measurements and correcting existing emission inventories, which are evaluated mainly on indirect data connected with population density, fuel consumption, etc. Within the framework of the project, the whole volume of data on the concentration of ground contaminants CO, NOx, SO2, CH4, obtained at regularly operated Moscow Ecological Monitoring stations and at OIAP stations from 2005 to 2014, was systematized. Observation data on pollution concentrations are supplemented by measurements of their integral content in the atmospheric boundary layer, obtained by differential spectroscopy methods (MAX DOAS, ZDOAS) at stationary stations and by passing Moscow with DOAS-equipped car. The paper present preliminary estimates of pollution emissions in the Moscow region, obtained on the basis of the collected array of experimental data. The estimations of pollutant emissions from Moscow were obtained experimentally in a few ways: (1) on the basis of network observations of surface concentrations, (2) on the basis of measurements in the atmospheric layer 0-348 m at Ostankino TV tower, (3) on the basis of the integral pollutant (NO2) content in ABL obtained by DOAS technique from stationary stations, and (4) using a car with DOAS equipment traveling over the closed route around Moscow (for NO2). All experimental approaches yielded close values of pollution emissions for Moscow. Trends in emissions of CO, NOx, and CH4 are negative, and the trend of SO2 emission is positive from 2005 to 2014.

Expenditure Distribution Trends with Regard to the Availability of Funds in the DOA and DOAF Budgets.

DTIC Science & Technology

1987-06-01

TERMAS (Continu*on r evere of fleUdr’y and ident-loy by block number) GUp eGRU Budget, Outlays, DOAF, DOA, DOD, Expenditures, Increment alism This thesis...34ONE (Ilo de Arid Code) 22C ~fF(E SYo Prfso TervL McCafferv 408-646-2554 1Code 54Mm DO’ FORtM 1-473.5.4 MAR 83 APR ed-ton -ay be used wmu ntl " awsted ...SCHOOL June 1987 Author: Michael FkA.’ atto Approved by: MCC ! s~visor Dan Boer Seoand Reade ill A. treer ., r .. Chairman .zParr~to nstive Sciences

Two-dimensional grid-free compressive beamforming.

PubMed

Yang, Yang; Chu, Zhigang; Xu, Zhongming; Ping, Guoli

2017-08-01

Compressive beamforming realizes the direction-of-arrival (DOA) estimation and strength quantification of acoustic sources by solving an underdetermined system of equations relating microphone pressures to a source distribution via compressive sensing. The conventional method assumes DOAs of sources to lie on a grid. Its performance degrades due to basis mismatch when the assumption is not satisfied. To overcome this limitation for the measurement with plane microphone arrays, a two-dimensional grid-free compressive beamforming is developed. First, a continuum based atomic norm minimization is defined to denoise the measured pressure and thus obtain the pressure from sources. Next, a positive semidefinite programming is formulated to approximate the atomic norm minimization. Subsequently, a reasonably fast algorithm based on alternating direction method of multipliers is presented to solve the positive semidefinite programming. Finally, the matrix enhancement and matrix pencil method is introduced to process the obtained pressure and reconstruct the source distribution. Both simulations and experiments demonstrate that under certain conditions, the grid-free compressive beamforming can provide high-resolution and low-contamination imaging, allowing accurate and fast estimation of two-dimensional DOAs and quantification of source strengths, even with non-uniform arrays and noisy measurements.

Industrial hygiene evaluation of thermal degradation products from PVC film in meat-wrapping operations.

PubMed

Cook, W A

1980-07-01

An industrial hygiene evaluation is presented concerning experimental data included in the preceding paper on thermal degradation products from hot-wire and "cool"-rod cutting of PVC film but, in this paper, limited to film used in meat-wrapping operations. Room air concentrations of less than 0.2 ppm HCl and less than 0.05 ppm benzene can be maintained by a number of factors, including minimal dilution ventilation. Estimates of room air concentrations of degradation products are presented using average values of amounts produced per cut. The relation of these concentrations to TLV's is given, together with methods of suggesting TLV's for substances not listed by ACGIH or OSHA. Room air concentrations for the 12 degradation products for which TLV's are assigned, based on average values per cut, were no greater than 0.3% of accepted limits. Room air concentrations of DOA are not determinable from available data but present information does not indicate that exposure to DOA causes airway hyperreactivity. The cool rod, rather than the hot wire, is recommended as good industrial hygiene practice, producing no apparent PVC degradation products, even though similar amounts of DOA are volatilized.

Flight parameter estimation using instantaneous frequency and direction of arrival measurements from a single acoustic sensor node.

PubMed

Lo, Kam W

2017-03-01

When an airborne sound source travels past a stationary ground-based acoustic sensor node in a straight line at constant altitude and constant speed that is not much less than the speed of sound in air, the movement of the source during the propagation of the signal from the source to the sensor node (commonly referred to as the "retardation effect") enables the full set of flight parameters of the source to be estimated by measuring the direction of arrival (DOA) of the signal at the sensor node over a sufficiently long period of time. This paper studies the possibility of using instantaneous frequency (IF) measurements from the sensor node to improve the precision of the flight parameter estimates when the source spectrum contains a harmonic line of constant frequency. A simplified Cramer-Rao lower bound analysis shows that the standard deviations in the estimates of the flight parameters can be reduced when IF measurements are used together with DOA measurements. Two flight parameter estimation algorithms that utilize both IF and DOA measurements are described and their performances are evaluated using both simulated data and real data.

A new root-based direction-finding algorithm

NASA Astrophysics Data System (ADS)

Wasylkiwskyj, Wasyl; Kopriva, Ivica; DoroslovačKi, Miloš; Zaghloul, Amir I.

2007-04-01

Polynomial rooting direction-finding (DF) algorithms are a computationally efficient alternative to search-based DF algorithms and are particularly suitable for uniform linear arrays of physically identical elements provided that mutual interaction among the array elements can be either neglected or compensated for. A popular algorithm in such situations is Root Multiple Signal Classification (Root MUSIC (RM)), wherein the estimation of the directions of arrivals (DOA) requires the computation of the roots of a (2N - 2) -order polynomial, where N represents number of array elements. The DOA are estimated from the L pairs of roots closest to the unit circle, where L represents number of sources. In this paper we derive a modified root polynomial (MRP) algorithm requiring the calculation of only L roots in order to estimate the L DOA. We evaluate the performance of the MRP algorithm numerically and show that it is as accurate as the RM algorithm but with a significantly simpler algebraic structure. In order to demonstrate that the theoretically predicted performance can be achieved in an experimental setting, a decoupled array is emulated in hardware using phase shifters. The results are in excellent agreement with theory.

Direction of Arrival Estimation for MIMO Radar via Unitary Nuclear Norm Minimization

PubMed Central

Wang, Xianpeng; Huang, Mengxing; Wu, Xiaoqin; Bi, Guoan

2017-01-01

In this paper, we consider the direction of arrival (DOA) estimation issue of noncircular (NC) source in multiple-input multiple-output (MIMO) radar and propose a novel unitary nuclear norm minimization (UNNM) algorithm. In the proposed method, the noncircular properties of signals are used to double the virtual array aperture, and the real-valued data are obtained by utilizing unitary transformation. Then a real-valued block sparse model is established based on a novel over-complete dictionary, and a UNNM algorithm is formulated for recovering the block-sparse matrix. In addition, the real-valued NC-MUSIC spectrum is used to design a weight matrix for reweighting the nuclear norm minimization to achieve the enhanced sparsity of solutions. Finally, the DOA is estimated by searching the non-zero blocks of the recovered matrix. Because of using the noncircular properties of signals to extend the virtual array aperture and an additional real structure to suppress the noise, the proposed method provides better performance compared with the conventional sparse recovery based algorithms. Furthermore, the proposed method can handle the case of underdetermined DOA estimation. Simulation results show the effectiveness and advantages of the proposed method. PMID:28441770

Two-Dimensional DOA and Polarization Estimation for a Mixture of Uncorrelated and Coherent Sources with Sparsely-Distributed Vector Sensor Array

PubMed Central

Si, Weijian; Zhao, Pinjiao; Qu, Zhiyu

2016-01-01

This paper presents an L-shaped sparsely-distributed vector sensor (SD-VS) array with four different antenna compositions. With the proposed SD-VS array, a novel two-dimensional (2-D) direction of arrival (DOA) and polarization estimation method is proposed to handle the scenario where uncorrelated and coherent sources coexist. The uncorrelated and coherent sources are separated based on the moduli of the eigenvalues. For the uncorrelated sources, coarse estimates are acquired by extracting the DOA information embedded in the steering vectors from estimated array response matrix of the uncorrelated sources, and they serve as coarse references to disambiguate fine estimates with cyclical ambiguity obtained from the spatial phase factors. For the coherent sources, four Hankel matrices are constructed, with which the coherent sources are resolved in a similar way as for the uncorrelated sources. The proposed SD-VS array requires only two collocated antennas for each vector sensor, thus the mutual coupling effects across the collocated antennas are reduced greatly. Moreover, the inter-sensor spacings are allowed beyond a half-wavelength, which results in an extended array aperture. Simulation results demonstrate the effectiveness and favorable performance of the proposed method. PMID:27258271

Learning Sequential Composition Control.

PubMed

Najafi, Esmaeil; Babuska, Robert; Lopes, Gabriel A D

2016-11-01

Sequential composition is an effective supervisory control method for addressing control problems in nonlinear dynamical systems. It executes a set of controllers sequentially to achieve a control specification that cannot be realized by a single controller. As these controllers are designed offline, sequential composition cannot address unmodeled situations that might occur during runtime. This paper proposes a learning approach to augment the standard sequential composition framework by using online learning to handle unforeseen situations. New controllers are acquired via learning and added to the existing supervisory control structure. In the proposed setting, learning experiments are restricted to take place within the domain of attraction (DOA) of the existing controllers. This guarantees that the learning process is safe (i.e., the closed loop system is always stable). In addition, the DOA of the new learned controller is approximated after each learning trial. This keeps the learning process short as learning is terminated as soon as the DOA of the learned controller is sufficiently large. The proposed approach has been implemented on two nonlinear systems: 1) a nonlinear mass-damper system and 2) an inverted pendulum. The results show that in both cases a new controller can be rapidly learned and added to the supervisory control structure.

Mitochondrial optic neuropathies – Disease mechanisms and therapeutic strategies

PubMed Central

Yu-Wai-Man, Patrick; Griffiths, Philip G.; Chinnery, Patrick F.

2011-01-01

Leber hereditary optic neuropathy (LHON) and autosomal-dominant optic atrophy (DOA) are the two most common inherited optic neuropathies in the general population. Both disorders share striking pathological similarities, marked by the selective loss of retinal ganglion cells (RGCs) and the early involvement of the papillomacular bundle. Three mitochondrial DNA (mtDNA) point mutations; m.3460G>A, m.11778G>A, and m.14484T>C account for over 90% of LHON cases, and in DOA, the majority of affected families harbour mutations in the OPA1 gene, which codes for a mitochondrial inner membrane protein. Optic nerve degeneration in LHON and DOA is therefore due to disturbed mitochondrial function and a predominantly complex I respiratory chain defect has been identified using both in vitro and in vivo biochemical assays. However, the trigger for RGC loss is much more complex than a simple bioenergetic crisis and other important disease mechanisms have emerged relating to mitochondrial network dynamics, mtDNA maintenance, axonal transport, and the involvement of the cytoskeleton in maintaining a differential mitochondrial gradient at sites such as the lamina cribosa. The downstream consequences of these mitochondrial disturbances are likely to be influenced by the local cellular milieu. The vulnerability of RGCs in LHON and DOA could derive not only from tissue-specific, genetically-determined biological factors, but also from an increased susceptibility to exogenous influences such as light exposure, smoking, and pharmacological agents with putative mitochondrial toxic effects. Our concept of inherited mitochondrial optic neuropathies has evolved over the past decade, with the observation that patients with LHON and DOA can manifest a much broader phenotypic spectrum than pure optic nerve involvement. Interestingly, these phenotypes are sometimes clinically indistinguishable from other neurodegenerative disorders such as Charcot-Marie-Tooth disease, hereditary spastic paraplegia, and multiple sclerosis, where mitochondrial dysfunction is also thought to be an important pathophysiological player. A number of vertebrate and invertebrate disease models has recently been established to circumvent the lack of human tissues, and these have already provided considerable insight by allowing direct RGC experimentation. The ultimate goal is to translate these research advances into clinical practice and new treatment strategies are currently being investigated to improve the visual prognosis for patients with mitochondrial optic neuropathies. PMID:21112411

MAX-DOAS measurements of tropospheric vertical profiles of aerosols, NO2, SO2 and HCHO in the suburban area of Xintai city, China: comparisons with aircraft and ground-based measurements, and investigation of transport

NASA Astrophysics Data System (ADS)

Wang, Yang; Dörner, Steffen; Wagner, Thomas; Wang, Yuying; He, Hao; Ren, Xinrong; Li, Zhanqing; Li, Donghui; Xu, Hua; Li, Zhengqiang; Xu, Jiwei; Liu, Dong; Wang, Zhenzhu; De Smedt, Isabelle; Theys, Nicolas

2017-04-01

Xingtai is one of the most polluted cities in China and is located on the western edge of the large industrial zone of the North China plain. The Taihang Mountains in the west of Xingtai block transport of polluted air mass towards western China and cause accumulation of pollutants along the mountains. Severely polluted air harms health of about seven million inhabitants in Xingtai. Air pollution also affects condensation nuclei for the formation of convective clouds, and thus potentially initiates heavy rainfall. In order to study the interaction of pollutants and clouds, the Atmosphere-Aerosol-Boundary Layer-Cloud (A2BC) Interaction Joint Experiment was held around Xingtai in the period from May to June 2016. Various instruments measuring gaseous pollutants, aerosols, clouds, precipitation, and radiance are operated at a monitoring station (37.18° N, 114.36° E) in the suburban area of Xintai city and aboard two aircrafts which fly up and down in spirals between 0.2 km and 4 km over the station. We operated a Multi Axis (MAX-) Differential Optical Absorption Spectroscopy (DOAS) instrument at the station in order to derive tropospheric vertical profiles of aerosols, NO2, SO2 and HCHO during daytime with a time resolution of about 10 minutes. We apply our profile inversion algorithm PriAM based on the optimal estimation theory to retrieve trace gas and aerosol profiles. The results are compared with other ground-based and aircraft measurements. In general reasonable consistency was found, but the comparison also revealed a considerable smoothing effect of the MAX-DOAS retrievals. The MAX-DOAS results are applied to characterize the vertical profiles and the diurnal cycles of the trace gas and aerosol pollutants. Lifted layers of pollutants, especially aerosols and SO2, were frequently observed during the campaign indicating frequent transport events of pollutants over the station. Rapid cleaning events of pollutants were also observed. We further investigate the effect of transport and the distribution of emission sources (e.g. the wind dependence of pollutants) using MAX-DOAS results in combination with satellite observations, and the HYSPLIT trajectory model.

Optimal dose of perineural dexmedetomidine for interscalene brachial plexus block to control postoperative pain in patients undergoing arthroscopic shoulder surgery: A prospective, double-blind, randomized controlled study.

PubMed

Jung, Hong Soo; Seo, Kwon Hui; Kang, Jae Hyuk; Jeong, Jin-Young; Kim, Yong-Shin; Han, Na-Re

2018-04-01

Adjuvant perineural dexmedetomidine can be used to prolong the analgesic effect of interscalene brachial plexus block (ISB). We investigated the optimal dose of dexmedetomidine in ISB for postoperative analgesia in patients undergoing arthroscopic shoulder surgery. One hundred patients scheduled for elective shoulder arthroscopic surgery were enrolled in this randomized, double-blind study. Ultrasound-guided ISB was performed before general anesthesia using 22 mL of ropivacaine 0.5% combined with 1, 1.5, or 2 μg/kg of dexmedetomidine (group D1, D2, and D3, respectively) or with normal saline as a control (group R, n = 25 per group). The primary outcome was the duration of analgesia (DOA), numeric pain rating scale (NRS), and consumption of additional analgesics during 36 h after ISB. Secondary outcome included durations of motor and sensory block (DOM and DOS), hemodynamic variables and sedation and dyspnea scores. Ninety-seven patients completed the study. The DOS, DOM, and DOA were significantly longer in the dexmedetomidine groups than in group R. The DOA was significantly longer in group D3 than in groups D1 (P = .026) and D2 (P = .039). The DOA was 808.13 ± 179.97, 1032.60 ± 288.14, 1042.04 ± 188.13, and 1223.96 ± 238.06 min in groups R, D1, D2, and D3, respectively. The NRS score was significantly higher in group R than in the dexmedetomidine groups 12 h after ISB (P < .001) and significantly lower in group D3 than in the other groups 18 h after ISB (P = .02). The incidence of hypotension was higher in groups D2 and D3 than in group R during surgery (P = .008 and P = .011, respectively). There were no significant differences in consumption of rescue analgesics, sedation, and dyspnea scores between the study groups. Perineural dexmedetomidine 2 μg/kg could be the optimal dose in ISB for arthroscopic shoulder surgery in that it provides an adequate DOA. However, this dose was associated with increased risk of hypotension.

Vertical profiles of pollutant gases measured with passive DOAS in the Po Valley devoted to satellite and chemical model data comparison

NASA Astrophysics Data System (ADS)

Masieri, S.; Petritoli, A.; Kostadinov, I.; Bortoli, D.; Premuda, M.; Ravegnani, F.; Giovanelli, G.

2009-04-01

In the frame of QUITSAT Italian pilot project (Air QUality with InTegration of ground-based and SAtellite measurement and chemical Transport model), two field campaigns were made in S.Pietro Capofiume (44.65˚ N; 11.37˚ E) and Bologna (44.52˚ N; 11.34˚ E) to provide concentration of ground particular matter and gaseous pollutants, namely nitrogen dioxide (NO2), formaldehyde (HCHO), sulphur dioxide (SO2) and ozone (O3). The aim of the campaigns was to provide experimental data need for tests and improvement of algorithms developed for integration of satellite and ground-based data together with chemical transport model data in order to retrieve air quality in the QUITSAT domain. Ground based measurements were carried out within a network of in-situ analyser in the Po Valley and with a scanning multi-axis DOAS (Differential Optical Absorption Spectroscopy) spectrometer system developed at ISAC-CNR institute [1], in collaboration with Geophysics Center of Evora [2]. TropoGAS (TROPOspheric Gas Analyser Spectrometer) spectrometer permits active and passive DOAS measurements at the chosen angles: α =1,2,3,6,10,15,20,90 and another measurement was taken along the sun direction. A Xenon lamp installed at 1km of distance from spectrometer was used as a reference concentration measured in the same place, and these values shows good agreement with in-situ analyser concentration. Gas spectral absorption was evaluated with DOAS [3] algorithms from 430 to 500 nm in two different windows: first from 436 to 460 nm for NO2 retrieval; second from 460 to 500 nm for O4 (best line at 477 nm) and NO2. Air Mass Factor (AMF) was calculated using PROMSAR (PROcessing of Multi-Scattered Atmospheric Radiation) model [4], that is a backward Montecarlo Radiative Transfer Model (RTM). An apposite inversion method [5][6], was applied to retrieve profiles of the target gases from their Slant Column Densities (SCD), using advanced approaches involving measurement of the atmospheric O4 whose profile depends strongly on altitude [7][8]. Due to this it is also possible gain information about the atmospheric aerosol profile to set better the parameters in AMF Calculation, and then retrieve gas concentration's profiles. The NO2 concentrations measured were in the range of 0.5-25 ppb, as we expect for summer periods in rural area. GAMES (Gas Aerosol Modelling Evaluation System) model [9] was used in this work to have a reference about vertical distribution of gases (the model provides concentration profiles along 4km of altitude, with 11 growing thickness levels). Result of comparison with profile caculate by the model and profile calulate by the Multi-axis DOAS technique, is presented and then it is compared with Satellite column retrieved (with our satellite Data processor) from SCIAMACHY sensor (onboard on ENVISAT platform) and (directly NO2 Tropospheric Vertical Column provided by KNMI) from OMI (onboard on AURA platform). Good agreements between used series are shown and improvements for this methodology are discussed. One month of measurement has been taken in consideration starting from 15 May to 15 June of 2007. Vertical structure of most important trace gases calculated with model has strong correlation with the off-axis DOAS one (in some cases with R2=0,8), so better understanding of profiles and chemistry behaviour can be studied. The experience acquired within QUITSAT activity appears valuable contribution for enlargement of the DOAS applications what concern atmospheric chemistry studies, operative monitoring of the air quality over regional scale as well as satellite data validation. Deployed approaches are not restricted to NO2 but could be applied to other gases e.g. ozone, formaldehyde etc.. Key words: Off axis DOAS, NO2, CTM, AMF, gas profiles, satellite data validation, 1 2. BIBLIOGRAPHY [1] F. Evangelisti, A. Baroncelli, P. Bonasoni, G. Giovanelli, And F. Ravegnani, "Differential optical absorption spectrometer for measurement of tropospheric pollutants," Applied Optics, 34, pp. 2737-2744, 1995. [2] D. Bortoli, "SPATRAM - Spectrometer for ATmospheric TRAcers Measurements, a Prototype Equipment for the monitoring of minor compounds of the atmosphere," PhD dissertation, University of Evora, Evora, Portugal, 2005. [3] U. Platt, "Modern methods of the measurements of atmospheric trace gases," Phys. Chem., 1, pp. 5409-5415, 1999. [4] E. Palazzi, A. Petritoli, G. Giovanelli, I. Kostadinov, D. Bortoli, and F. Ravegnani, "PROMSAR: A multiple scattering atmospheric model for the analysis of DOAS remote sensing measurements," Adv. Space. Res., 36, pp. 1007-1014, 2005. [5] M. Chahine, "A general relaxation method for inverse solutionof the full radiative transfer equation," J. Atmos. Sci., 29, 4, pp. 741-747, 1972. [6] E. Palazzi, A. Petritoli, F. Ravegnani, I. Kostadinov, D. Bortoli, S. Masieri, M. Premuda, and G. Giovanelli, "Retrieval of Gas Pollutants Vertical Profile in the Boundary Layer by Means of Multiple Axis DOAS," IEEE Transaction on Geoscience and Remote Sensing. Vol. 46, pp. 2796-2802, 10.1109/TGRS.2008.2000927, 2008. [7] T. Wagner, B. Dix, C. von Friedeburg, U. Frieß, S. Sanghavi, R. Sinreich, and U. Platt, "MAX-DOAS O4 measurements: A new technique to derive information on atmospheric aerosols—Principles and information content," J. Geophys. Res., 109, D22205, doi:10.1029/2004JD004904, 2004. [8] A. Petritoli, Bonasoni P., Giovanelli G., Ravegnani F., Kostadinov I., Bortoli D., Weiss A., Schaub D., Richter A. and F. Fortezza, "First comparison between ground-based and satellite-borne measurements of tropospheric nitrogen dioxide in the Po basin," J. Geophys. Res., 109, D15307, doi: 10.1029/2004JD004547, 2004. [9] M. Volta, and G. Finzi, "GAMES, a comprehensive Gas Aerosol Modelling Evaluation System," Environ. Model. Software, 21, pp. 587-594, 2006.

Monitoring stratospheric chlorine activation from time series of OClO DSCDs above Kiruna using ground-based zenith sky DOAS observations

NASA Astrophysics Data System (ADS)

Gu, Myojeong; Enell, Carl-Fredrik; Pukite, Janis; Platt, Ulrich; Raffalski, Uwe; Wagner, Thomas

2017-04-01

After to the Montreal protocol and amendments, the production of CFCs was strongly reduced. Since then scientists have steadily made efforts to monitor the amount of chlorine compounds which are responsible for the destruction of ozone in the stratosphere. Although very recent research of stratospheric ozone indicates an ozone recovery, ozone depletion is still observed in the polar spring and is expected to last for about another 70 years according to the WMO. Therefore, continuous observation and analysis of the stratospheric ozone as well as other stratospheric trace gases are highly demanded. Several previous studies have investigated OClO which is an indicator for stratospheric chlorine activation using satellite, ground-based, and balloon remote sensing measurements. In this work, we investigate long-term time series of OClO DSCDs (Differential Slant Column densities) above Kiruna, Sweden (67.84°N, 20.41°E) which is located inside the Arctic Circle by using the ground-based zenith sky DOAS measurements. Since our measurements are performed at the fixed site, for the interpretation also the relative position of the polar vortex has to be considered. Our long-term data obtained during about 15 years allows us to classify the dependence of the OClO amount on the various meteorological conditions. Our data show a large variability with high OClO SCDs in cold, and low OClO SCDs in warm winters. Our measurements also allow to investigate the effect of the chlorine activation and its duration on the strength of the ozone destruction.

Linear Vector Quantisation and Uniform Circular Arrays based decoupled two-dimensional angle of arrival estimation

NASA Astrophysics Data System (ADS)

Ndaw, Joseph D.; Faye, Andre; Maïga, Amadou S.

2017-05-01

Artificial neural networks (ANN)-based models are efficient ways of source localisation. However very large training sets are needed to precisely estimate two-dimensional Direction of arrival (2D-DOA) with ANN models. In this paper we present a fast artificial neural network approach for 2D-DOA estimation with reduced training sets sizes. We exploit the symmetry properties of Uniform Circular Arrays (UCA) to build two different datasets for elevation and azimuth angles. Linear Vector Quantisation (LVQ) neural networks are then sequentially trained on each dataset to separately estimate elevation and azimuth angles. A multilevel training process is applied to further reduce the training sets sizes.

Fast Noncircular 2D-DOA Estimation for Rectangular Planar Array

PubMed Central

Xu, Lingyun; Wen, Fangqing

2017-01-01

A novel scheme is proposed for direction finding with uniform rectangular planar array. First, the characteristics of noncircular signals and Euler’s formula are exploited to construct a new real-valued rectangular array data. Then, the rotational invariance relations for real-valued signal space are depicted in a new way. Finally the real-valued propagator method is utilized to estimate the pairing two-dimensional direction of arrival (2D-DOA). The proposed algorithm provides better angle estimation performance and can discern more sources than the 2D propagator method. At the same time, it has very close angle estimation performance to the noncircular propagator method (NC-PM) with reduced computational complexity. PMID:28417926

Direction of Radio Finding via MUSIC (Multiple Signal Classification) Algorithm for Hardware Design System

NASA Astrophysics Data System (ADS)

Zhang, Zheng

2017-10-01

Concept of radio direction finding systems, which use radio direction finding is based on digital signal processing algorithms. Thus, the radio direction finding system becomes capable to locate and track signals by the both. Performance of radio direction finding significantly depends on effectiveness of digital signal processing algorithms. The algorithm uses the Direction of Arrival (DOA) algorithms to estimate the number of incidents plane waves on the antenna array and their angle of incidence. This manuscript investigates implementation of the DOA algorithms (MUSIC) on the uniform linear array in the presence of white noise. The experiment results exhibit that MUSIC algorithm changed well with the radio direction.

An Improved DOA Estimation Approach Using Coarray Interpolation and Matrix Denoising

PubMed Central

Guo, Muran; Chen, Tao; Wang, Ben

2017-01-01

Co-prime arrays can estimate the directions of arrival (DOAs) of O(MN) sources with O(M+N) sensors, and are convenient to analyze due to their closed-form expression for the locations of virtual lags. However, the number of degrees of freedom is limited due to the existence of holes in difference coarrays if subspace-based algorithms such as the spatial smoothing multiple signal classification (MUSIC) algorithm are utilized. To address this issue, techniques such as positive definite Toeplitz completion and array interpolation have been proposed in the literature. Another factor that compromises the accuracy of DOA estimation is the limitation of the number of snapshots. Coarray-based processing is particularly sensitive to the discrepancy between the sample covariance matrix and the ideal covariance matrix due to the finite number of snapshots. In this paper, coarray interpolation based on matrix completion (MC) followed by a denoising operation is proposed to detect more sources with a higher accuracy. The effectiveness of the proposed method is based on the capability of MC to fill in holes in the virtual sensors and that of MC denoising operation to reduce the perturbation in the sample covariance matrix. The results of numerical simulations verify the superiority of the proposed approach. PMID:28509886

An Improved DOA Estimation Approach Using Coarray Interpolation and Matrix Denoising.

PubMed

Guo, Muran; Chen, Tao; Wang, Ben

2017-05-16

Co-prime arrays can estimate the directions of arrival (DOAs) of O ( M N ) sources with O ( M + N ) sensors, and are convenient to analyze due to their closed-form expression for the locations of virtual lags. However, the number of degrees of freedom is limited due to the existence of holes in difference coarrays if subspace-based algorithms such as the spatial smoothing multiple signal classification (MUSIC) algorithm are utilized. To address this issue, techniques such as positive definite Toeplitz completion and array interpolation have been proposed in the literature. Another factor that compromises the accuracy of DOA estimation is the limitation of the number of snapshots. Coarray-based processing is particularly sensitive to the discrepancy between the sample covariance matrix and the ideal covariance matrix due to the finite number of snapshots. In this paper, coarray interpolation based on matrix completion (MC) followed by a denoising operation is proposed to detect more sources with a higher accuracy. The effectiveness of the proposed method is based on the capability of MC to fill in holes in the virtual sensors and that of MC denoising operation to reduce the perturbation in the sample covariance matrix. The results of numerical simulations verify the superiority of the proposed approach.

Impact of engine lubricant properties on regulated gaseous emissions of 2000-2001 model-year gasoline vehicles.

PubMed

Durbin, Thomas D; Sauer, Claudia G; Pisano, John T; Rhee, Sam H; Huai, Tao; Miller, J Wayne; MacKay, Gervase I; Robbins, John; Gamble, Heather; Hochhauser, Albert M; Ingham, Michael C; Gorse, Robert A; Beard, Loren K

2004-03-01

The impact of the sulfur (S) content in lubricating oil was evaluated for four ultra-low-emission vehicles and two super-ultra-low-emission vehicles, all with low mileage. The S content in the lube oils ranged from 0.01 to 0.76%, while the S content of the gasoline was fixed at 0.2 ppmw. Vehicles were configured with aged catalysts and tested over the Federal Test Procedure, at idle and at 50-mph cruise conditions. In all testing modes, variations in the S level of the lubricant did not significantly affect the regulated gas-phase tailpipe emissions. In addition to the regulated gas-phase emissions, a key element of the research was measuring the engine-out sulfur dioxide (SO2) in near-real-time. This research used a new methodology based on a differential optical absorption spectrometer (DOAS) to measure SO2 from the lubricants used in this study. With the DOAS, the contribution of SO2 emissions for the highest-S lubricant was found to range from less than 1 to 6 ppm on a gasoline S equivalent basis over the range of vehicles and test cycles used. The development and operation of the DOAS is discussed in this paper.

ESPRIT-Like Two-Dimensional DOA Estimation for Monostatic MIMO Radar with Electromagnetic Vector Received Sensors under the Condition of Gain and Phase Uncertainties and Mutual Coupling

PubMed Central

Zhang, Yongshun; Zheng, Guimei; Feng, Cunqian; Tang, Jun

2017-01-01

In this paper, we focus on the problem of two-dimensional direction of arrival (2D-DOA) estimation for monostatic MIMO Radar with electromagnetic vector received sensors (MIMO-EMVSs) under the condition of gain and phase uncertainties (GPU) and mutual coupling (MC). GPU would spoil the invariance property of the EMVSs in MIMO-EMVSs, thus the effective ESPRIT algorithm unable to be used directly. Then we put forward a C-SPD ESPRIT-like algorithm. It estimates the 2D-DOA and polarization station angle (PSA) based on the instrumental sensors method (ISM). The C-SPD ESPRIT-like algorithm can obtain good angle estimation accuracy without knowing the GPU. Furthermore, it can be applied to arbitrary array configuration and has low complexity for avoiding the angle searching procedure. When MC and GPU exist together between the elements of EMVSs, in order to make our algorithm feasible, we derive a class of separated electromagnetic vector receiver and give the S-SPD ESPRIT-like algorithm. It can solve the problem of GPU and MC efficiently. And the array configuration can be arbitrary. The effectiveness of our proposed algorithms is verified by the simulation result. PMID:29072588

ESPRIT-Like Two-Dimensional DOA Estimation for Monostatic MIMO Radar with Electromagnetic Vector Received Sensors under the Condition of Gain and Phase Uncertainties and Mutual Coupling.

PubMed

Zhang, Dong; Zhang, Yongshun; Zheng, Guimei; Feng, Cunqian; Tang, Jun

2017-10-26

In this paper, we focus on the problem of two-dimensional direction of arrival (2D-DOA) estimation for monostatic MIMO Radar with electromagnetic vector received sensors (MIMO-EMVSs) under the condition of gain and phase uncertainties (GPU) and mutual coupling (MC). GPU would spoil the invariance property of the EMVSs in MIMO-EMVSs, thus the effective ESPRIT algorithm unable to be used directly. Then we put forward a C-SPD ESPRIT-like algorithm. It estimates the 2D-DOA and polarization station angle (PSA) based on the instrumental sensors method (ISM). The C-SPD ESPRIT-like algorithm can obtain good angle estimation accuracy without knowing the GPU. Furthermore, it can be applied to arbitrary array configuration and has low complexity for avoiding the angle searching procedure. When MC and GPU exist together between the elements of EMVSs, in order to make our algorithm feasible, we derive a class of separated electromagnetic vector receiver and give the S-SPD ESPRIT-like algorithm. It can solve the problem of GPU and MC efficiently. And the array configuration can be arbitrary. The effectiveness of our proposed algorithms is verified by the simulation result.

Effective direction of arrival estimation of gunshot signals from an in-flight unmanned aerial vehicle

NASA Astrophysics Data System (ADS)

Ribeiro, Juliano G. C.; Serrenho, Felipe G.; Apolinário, José A.; Ramos, António L. L.

2018-04-01

Spotting a shooter from a drone has been the subject of great interest lately due to its many applications in the fields of defense and security and law enforcement. Using a drone can be an effective way to detect potential threats in many real-life scenarios. Nevertheless, acoustic signals recorded from a drone usually exhibit a very low SNR, mainly due to the distance to the source and the proximity of the sensors to the propellers. This is a serious limiting factor and, therefore, the use of signal enhancement techniques is required. This work addresses the problem of determining the Direction-of-Arrival (DoA) of the muzzle blast, captured using a planar microphone array mounted on a commercial DJI PHANTOM 4 drone in flight. This new shooter localization method that relies solely on detecting and estimating the DoA of the muzzle blast. However, the typical low SNR in this scenario requires the use of preprocessing techniques, such as signal clipping and median filtering, to enhance the signal of interest (muzzle blast). In addition, we employ a recently introduced improved data selection DoA estimation method suitable for gunshot signals recorded from a low to medium altitude mobile aerial platform. Positive results achieved indicate that this approach is effective and of practical interest.

MAX-DOAS measurements of African continental pollution outflow over the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Behrens, Lisa K.; Hilboll, Andreas; Peters, Enno; Richter, Andreas; Alvarado, Leonardo; Wittrock, Folkard; Burrows, John P.; Vrekoussis, Mihalis

2017-04-01

Enhanced levels of atmospheric key pollutants can regularly be identified over the Atlantic Ocean in global trace gas maps retrieved from satellite measurements. The aim of the DFG project COPMAR (Continental outflow of pollutants towards the marine troposphere) was to validate these enhanced values using ship-based measurements and to identify the spatial gradients of the pollutants NO2, CHOCHO, and HCHO over the Atlantic Ocean. Therefore, a multi-axis differential optical absorption spectrometer (MAX-DOAS) was installed on board the research vessel Maria S. Merian for the cruise MSM58/2. This cruise was conducted in October 2016 and went from Ponta Delgada (Azores) to Cape Town (South Africa), crossing between Cape Verde and the African continent. The instrument was continuously scanning the horizon looking towards the African continent, and the ship sailed at nearly constant speed during the whole cruise. In this study, we present the results from the MAX-DOAS measurements for the three species. We discuss the influence of different fit settings and a-priori assumptions on the results and present the observed spatial gradients along the cruise track. Finally, we compare our results with satellite measurements by the GOME-2 and OMI instruments and discuss possible sources of the discrepancies.

Delay-and-sum beamforming for direction of arrival estimation applied to gunshot acoustics

NASA Astrophysics Data System (ADS)

Ramos, António L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald

2011-06-01

Sniper positioning systems described in the literature use a two-step algorithm to estimate the sniper's location. First, the shockwave and the muzzle blast acoustic signatures must be detected and recognized, followed by an estimation of their respective direction-of-arrival (DOA). Second, the actual sniper's position is calculated based on the estimated DOA via an iterative algorithm that varies from system to system. The overall performance of such a system, however, is highly compromised when the first step is not carried out successfully. Currently available systems rely on a simple calculation of differences of time-of-arrival to estimate angles-of-arrival. This approach, however, lacks robustness by not taking full advantage of the array of sensors. This paper shows how the delay-and-sum beamforming technique can be applied to estimate the DOA for both the shockwave and the muzzle blast. The method has the twofold advantage of 1) adding an array gain of 10 logM, i.e., an increased SNR of 6 dB for a 4-microphone array, which is equivalent to doubling the detection range assuming free-field propagation; and 2) offering improved robustness in handling single- and multi-shots events as well as reflections by taking advantage of the spatial filtering capability.

Are non-linearity effects of absorption important for MAX-DOAS observations?

NASA Astrophysics Data System (ADS)

Pukite, Janis; Wang, Yang; Wagner, Thomas

2017-04-01

For scattered light observations the absorption optical depth depends non-linearly on the trace gas concentrations if their absorption is strong. This is the case because the Beer-Lambert law is generally not applicable for scattered light measurements due to many (i.e. more than one) light paths contributing to the measurement. While in many cases a linear approximation can be made, for scenarios with strong absorption non-linear effects cannot always be neglected. This is especially the case for observation geometries with spatially extended and diffuse light paths, especially in satellite limb geometry but also for nadir measurements as well. Fortunately the effects of non-linear effects can be quantified by means of expanding the radiative transfer equation in a Taylor series with respect to the trace gas absorption coefficients. Herewith if necessary (1) the higher order absorption structures can be described as separate fit parameters in the DOAS fit and (2) the algorithm constraints of retrievals of VCDs and profiles can be improved by considering higher order sensitivity parameters. In this study we investigate the contribution of the higher order absorption structures for MAX-DOAS observation geometry for different atmospheric and ground properties (cloud and aerosol effects, trace gas amount, albedo) and geometry (different Sun and viewing angles).

Modal smoothing for analysis of room reflections measured with spherical microphone and loudspeaker arrays.

PubMed

Morgenstern, Hai; Rafaely, Boaz

2018-02-01

Spatial analysis of room acoustics is an ongoing research topic. Microphone arrays have been employed for spatial analyses with an important objective being the estimation of the direction-of-arrival (DOA) of direct sound and early room reflections using room impulse responses (RIRs). An optimal method for DOA estimation is the multiple signal classification algorithm. When RIRs are considered, this method typically fails due to the correlation of room reflections, which leads to rank deficiency of the cross-spectrum matrix. Preprocessing methods for rank restoration, which may involve averaging over frequency, for example, have been proposed exclusively for spherical arrays. However, these methods fail in the case of reflections with equal time delays, which may arise in practice and could be of interest. In this paper, a method is proposed for systems that combine a spherical microphone array and a spherical loudspeaker array, referred to as multiple-input multiple-output systems. This method, referred to as modal smoothing, exploits the additional spatial diversity for rank restoration and succeeds where previous methods fail, as demonstrated in a simulation study. Finally, combining modal smoothing with a preprocessing method is proposed in order to increase the number of DOAs that can be estimated using low-order spherical loudspeaker arrays.

Tropospheric nitrogen dioxide column retrieval based on ground-based zenith-sky DOAS observations

NASA Astrophysics Data System (ADS)

Tack, F. M.; Hendrick, F.; Pinardi, G.; Fayt, C.; Van Roozendael, M.

2013-12-01

A retrieval approach has been developed to derive tropospheric NO2 vertical column amounts from ground-based zenith-sky measurements of scattered sunlight. Zenith radiance spectra are observed in the visible range by the BIRA-IASB Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument and analyzed by the DOAS technique, based on a least-squares spectral fitting. In recent years, this technique has shown to be a well-suited remote sensing tool for monitoring atmospheric trace gases. The retrieval algorithm is developed and validated based on a two month dataset acquired from June to July 2009 in the framework of the Cabauw (51.97° N, 4.93° E) Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI). Once fully operational, the retrieval approach can be applied to observations from stations of the Network for the Detection of Atmospheric Composition Change (NDACC). The obtained tropospheric vertical column amounts are compared with the multi-axis retrieval from the BIRA-IASB MAX-DOAS instrument and the retrieval from a zenith-viewing only SAOZ instrument (Système d'Analyse par Observations Zénithales), owned by Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS). First results show a good agreement for the whole time series with the multi-axis retrieval (R = 0.82; y = 0.88x + 0.30) as well as with the SAOZ retrieval (R = 0.85; y = 0.76x + 0.28 ). Main error sources arise from the uncertainties in the determination of tropospheric and stratospheric air mass factors, the stratospheric NO2 abundances and the residual amount in the reference spectrum. However zenith-sky measurements have been commonly used over the last decades for stratospheric monitoring, this study also illustrates the suitability for retrieval of tropospheric column amounts. As there are long time series of zenith-sky acquisitions available, the developed approach offers new perspectives with regard to the use of observations from the NDACC stations.

A Comparison of MODIS and DOAS Sulfur Dioxide Measurements of the April 24, 2004 Eruption of Anatahan Volcano, Mariana Islands

NASA Astrophysics Data System (ADS)

Meier, V. L.; Scuderi, L.; Fischer, T.; Realmuto, V.; Hilton, D.

2006-12-01

Measurements of volcanic SO2 emissions provide insight into the processes working below a volcano, which can presage volcanic events. Being able to measure SO2 in near real-time is invaluable for the planning and response of hazard mitigation teams. Currently, there are several methods used to quantify the SO2 output of degassing volcanoes. Ground and aerial-based measurements using the differential optical absorption spectrometer (mini-DOAS) provide real-time estimates of SO2 output. Satellite-based measurements, which can provide similar estimates in near real-time, have increasingly been used as a tool for volcanic monitoring. Direct Broadcast (DB) real-time processing of remotely sensed data from NASA's Earth Observing System (EOS) satellites (MODIS Terra and Aqua) presents volcanologists with a range of spectral bands and processing options for the study of volcanic emissions. While the spatial resolution of MODIS is 1 km in the Very Near Infrared (VNIR) and Thermal Infrared (TIR), a high temporal resolution and a wide range of radiance measurements in 32 channels between VNIR and TIR combine to provide a versatile space borne platform to monitor SO2 emissions from volcanoes. An important question remaining to be answered is how well do MODIS SO2 estimates compare with DOAS estimates? In 2004 ground-based plume measurements were collected on April 24th and 25th at Anatahan volcano in the Mariana Islands using a mini-DOAS (Fischer and Hilton). SO2 measurements for these same dates have also been calculated using MODIS images and SO2 mapping software (Realmuto). A comparison of these different approaches to the measurement of SO2 for the same plume is presented. Differences in these observations are used to better quantify SO2 emissions, to assess the current mismatch between ground based and remotely sensed retrievals, and to develop an approach to continuously and accurately monitor volcanic activity from space in near real-time.

Sample entropy analysis for the estimating depth of anaesthesia through human EEG signal at different levels of unconsciousness during surgeries.

PubMed

Liu, Quan; Ma, Li; Fan, Shou-Zen; Abbod, Maysam F; Shieh, Jiann-Shing

2018-01-01

Estimating the depth of anaesthesia (DoA) in operations has always been a challenging issue due to the underlying complexity of the brain mechanisms. Electroencephalogram (EEG) signals are undoubtedly the most widely used signals for measuring DoA. In this paper, a novel EEG-based index is proposed to evaluate DoA for 24 patients receiving general anaesthesia with different levels of unconsciousness. Sample Entropy (SampEn) algorithm was utilised in order to acquire the chaotic features of the signals. After calculating the SampEn from the EEG signals, Random Forest was utilised for developing learning regression models with Bispectral index (BIS) as the target. Correlation coefficient, mean absolute error, and area under the curve (AUC) were used to verify the perioperative performance of the proposed method. Validation comparisons with typical nonstationary signal analysis methods (i.e., recurrence analysis and permutation entropy) and regression methods (i.e., neural network and support vector machine) were conducted. To further verify the accuracy and validity of the proposed methodology, the data is divided into four unconsciousness-level groups on the basis of BIS levels. Subsequently, analysis of variance (ANOVA) was applied to the corresponding index (i.e., regression output). Results indicate that the correlation coefficient improved to 0.72 ± 0.09 after filtering and to 0.90 ± 0.05 after regression from the initial values of 0.51 ± 0.17. Similarly, the final mean absolute error dramatically declined to 5.22 ± 2.12. In addition, the ultimate AUC increased to 0.98 ± 0.02, and the ANOVA analysis indicates that each of the four groups of different anaesthetic levels demonstrated significant difference from the nearest levels. Furthermore, the Random Forest output was extensively linear in relation to BIS, thus with better DoA prediction accuracy. In conclusion, the proposed method provides a concrete basis for monitoring patients' anaesthetic level during surgeries.

New psychoactive substances in oral fluid of French and Belgian drivers in 2016.

PubMed

Richeval, Camille; Wille, Sarah Maria Richarda; Nachon-Phanithavong, Mélodie; Samyn, Nele; Allorge, Delphine; Gaulier, Jean-Michel

2018-04-06

Driving under the influence of drugs (DUID) is a worldwide problem with potentially major judiciary and life-threatening consequences. Up to now, only classical drugs of abuse (DOA) are tested for DUID detection. A challenging issue for drafting up-dated international drug policies is to take into account the recent and expanding new psychoactive substances (NPS) market. NPS consist in various narcotic or psychotropic drugs, most of them having a "legal" status, that replicate chemical structures and/or pharmacological effects of classical DOA. Although it is obvious that NPS can lead to impaired driving, the prevalence of NPS use in a DUID context is unknown since the applied roadside screening tests are not yet adapted for these compounds. Between January and December 2016, a total of 391 oral fluid specimens were obtained from used roadside immunochemical test devices for DOA (Drugwipe-5S ® device). These specimens were analyzed using liquid chromatography coupled with tandem mass spectrometry and high resolution mass spectrometry. NPS (mainly cathinone derivatives) were detected in 33 out of the 391 oral fluid samples. This NPS positivity rate of 8.4% in oral fluid of drivers who were submitted to a roadside drug testing in 2016 in France and in Belgium is comparable to the available blood data (NPS positivity rate of 7%) observed in 2015 in similar populations. Our results demonstrate the reality of driving after NPS use in French and Belgian drivers who were submitted to a roadside DOA test. As there is a lack of on-site detection methods to screen for NPS, the detection of NPS in a rapid and cost-effective DUID detection strategy is currently impossible. The expanding use of NPS, notably by drivers as reported here, and the inability of currently used drug detection tests, should be urgently addressed by road safety and law enforcement authorities. Copyright © 2018 Elsevier B.V. All rights reserved.

Hemispherical Scanning Imaging DOAS: Resolving nitrogen dioxide in the urban environment

NASA Astrophysics Data System (ADS)

Leigh, R. J.; Graves, R. R.; Lawrence, J.; Faloon, K.; Monks, P. S.

2012-12-01

Imaging DOAS techniques have been used for nitrogen dioxide and sulfer dioxide for a number of years. This presentation describes a novel system which images concentrations of nitrogen dioxide by scanning an imaging spectrometer 360 degrees azimuthally, covering a region from 5 degrees below the horizon, to the zenith. The instrument has been built at the University of Leicester (UK), on optical designs by Surrey Satellite Technologies Ltd, and incorporates an Offner relay with Schwarzchild fore-optics, in a rotating mount. The spectrometer offers high fidelity spectroscopic retrievals of nitrogen dioxide as a result of a reliable Gaussian line shape, zero smile and low chromatic aberration. The full hemispherical scanning provides complete coverage of nitrogen dioxide concentrations above approximately 5 ppbv in urban environments. Through the use of multiple instruments, the three-dimensional structure of nitrogen dioxide can be sampled and tomographically reconstructed, providing valuable information on nitrogen dioxide emissions and downwind exposure, in addition to new understanding of boundary layer dynamics through the use of nitrogen dioxide as a tracer. Furthermore, certain aerosol information can be retrieved through absolute intensity measurements in each azimuthal direction supplemented by traditional techniques of O4 spectroscopy. Such measurements provide a new tool for boundary layer measurement and monitoring at a time when air quality implications on human health and climate are under significant scrutiny. This presentation will describe the instrument and tomographic potential of this technique. First measurements were taken as part of the international PEGASOS campaign in Bologna, Italy. Results from these measurements will be shown, including imaging of enhanced NO2 in the Bologna urban boundary layer during a severe thunderstorm. A Hemispherical Scanning Imaging DOAS instrument operating in Bologna, Italy in June 2012. Visible in the background over Bologna is an instrumented Zepplin measuring NO2 and ozone among other species. A hemispherical panorama of nitrogen dioxide concentrations, as measured by the HSI-DOAS instrument in Bologna.

Investigations of temporal and spatial distribution of precursors SO2 and NO2 vertical columns in the North China Plain using mobile DOAS

NASA Astrophysics Data System (ADS)

Wu, Fengcheng; Xie, Pinhua; Li, Ang; Mou, Fusheng; Chen, Hao; Zhu, Yi; Zhu, Tong; Liu, Jianguo; Liu, Wenqing

2018-02-01

Recently, Chinese cities have suffered severe events of haze air pollution, particularly in the North China Plain (NCP). Investigating the temporal and spatial distribution of pollutants, emissions, and pollution transport is necessary to better understand the effect of various sources on air quality. We report on mobile differential optical absorption spectroscopy (mobile DOAS) observations of precursors SO2 and NO2 vertical columns in the NCP in the summer of 2013 (from 11 June to 7 July) in this study. The different temporal and spatial distributions of SO2 and NO2 vertical column density (VCD) over this area are characterized under various wind fields. The results show that transport from the southern NCP strongly affects air quality in Beijing, and the transport route, particularly SO2 transport on the route of Shijiazhuang-Baoding-Beijing, is identified. In addition, the major contributors to SO2 along the route of Shijiazhuang-Baoding-Beijing are elevated sources compared to low area sources for the route of Dezhou-Cangzhou-Tianjin-Beijing; this is found using the interrelated analysis between in situ and mobile DOAS observations during the measurement periods. Furthermore, the discussions on hot spots near the city of JiNan show that average observed width of polluted air mass is 11.83 and 17.23 km associated with air mass diffusion, which is approximately 60 km away from emission sources based on geometrical estimation. Finally, a reasonable agreement exists between the Ozone Monitoring Instrument (OMI) and mobile DOAS observations, with a correlation coefficient (R2) of 0.65 for NO2 VCDs. Both datasets also have a similar spatial pattern. The fitted slope of 0.55 is significantly less than unity, which can reflect the contamination of local sources, and OMI observations are needed to improve the sensitivities to the near-surface emission sources through improvements of the retrieval algorithm or the resolution of satellites.

An Adaptive Monitoring Scheme for Automatic Control of Anaesthesia in dynamic surgical environments based on Bispectral Index and Blood Pressure.

PubMed

Yu, Yu-Ning; Doctor, Faiyaz; Fan, Shou-Zen; Shieh, Jiann-Shing

2018-04-13

During surgical procedures, bispectral index (BIS) is a well-known measure used to determine the patient's depth of anesthesia (DOA). However, BIS readings can be subject to interference from many factors during surgery, and other parameters such as blood pressure (BP) and heart rate (HR) can provide more stable indicators. However, anesthesiologist still consider BIS as a primary measure to determine if the patient is correctly anaesthetized while relaying on the other physiological parameters to monitor and ensure the patient's status is maintained. The automatic control of administering anesthesia using intelligent control systems has been the subject of recent research in order to alleviate the burden on the anesthetist to manually adjust drug dosage in response physiological changes for sustaining DOA. A system proposed for the automatic control of anesthesia based on type-2 Self Organizing Fuzzy Logic Controllers (T2-SOFLCs) has been shown to be effective in the control of DOA under simulated scenarios while contending with uncertainties due to signal noise and dynamic changes in pharmacodynamics (PD) and pharmacokinetic (PK) effects of the drug on the body. This study considers both BIS and BP as part of an adaptive automatic control scheme, which can adjust to the monitoring of either parameter in response to changes in the availability and reliability of BIS signals during surgery. The simulation of different control schemes using BIS data obtained during real surgical procedures to emulate noise and interference factors have been conducted. The use of either or both combined parameters for controlling the delivery Propofol to maintain safe target set points for DOA are evaluated. The results show that combing BIS and BP based on the proposed adaptive control scheme can ensure the target set points and the correct amount of drug in the body is maintained even with the intermittent loss of BIS signal that could otherwise disrupt an automated control system.

Measurements of tropospheric NO2 in Romania using a zenith-sky mobile DOAS system and comparisons with satellite observations.

PubMed

Constantin, Daniel-Eduard; Merlaud, Alexis; Van Roozendael, Michel; Voiculescu, Mirela; Fayt, Caroline; Hendrick, François; Pinardi, Gaia; Georgescu, Lucian

2013-03-20

In this paper we present a new method for retrieving tropospheric NO2 Vertical Column Density (VCD) from zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements using mobile observations. This method was used during three days in the summer of 2011 in Romania, being to our knowledge the first mobile DOAS measurements peformed in this country. The measurements were carried out over large and different areas using a mobile DOAS system installed in a car. We present here a step-by-step retrieval of tropospheric VCD using complementary observations from ground and space which take into account the stratospheric contribution, which is a step forward compared to other similar studies. The detailed error budget indicates that the typical uncertainty on the retrieved NO2tropospheric VCD is less than 25%. The resulting ground-based data set is compared to satellite measurements from the Ozone Monitoring Instrument (OMI) and the Global Ozone Monitoring Experiment-2 (GOME-2). For instance, on 18 July 2011, in an industrial area located at 47.03°N, 22.45°E, GOME-2 observes a tropospheric VCD value of (3.4 ± 1.9) × 1015 molec./cm2, while average mobile measurements in the same area give a value of (3.4 ± 0.7) × 10(15) molec./cm2. On 22 August 2011, around Ploiesti city (44.99°N, 26.1°E), the tropospheric VCD observed by satellites is (3.3 ± 1.9) × 10(15) molec./cm2 (GOME-2) and (3.2 ± 3.2) × 10(15) molec./cm2 (OMI), while average mobile measurements give (3.8 ± 0.8) × 10(15) molec./cm2. Average ground measurements over "clean areas", on 18 July 2011, give (2.5 ± 0.6) × 10(15) molec./cm2 while the satellite observes a value of (1.8 ± 1.3) × 10(15) molec./cm2.

Measurements of Tropospheric NO2 in Romania Using a Zenith-Sky Mobile DOAS System and Comparisons with Satellite Observations

PubMed Central

Constantin, Daniel-Eduard; Merlaud, Alexis; Van Roozendael, Michel; Voiculescu, Mirela; Fayt, Caroline; Hendrick, François; Pinardi, Gaia; Georgescu, Lucian

2013-01-01

In this paper we present a new method for retrieving tropospheric NO2 Vertical Column Density (VCD) from zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements using mobile observations. This method was used during three days in the summer of 2011 in Romania, being to our knowledge the first mobile DOAS measurements peformed in this country. The measurements were carried out over large and different areas using a mobile DOAS system installed in a car. We present here a step-by-step retrieval of tropospheric VCD using complementary observations from ground and space which take into account the stratospheric contribution, which is a step forward compared to other similar studies. The detailed error budget indicates that the typical uncertainty on the retrieved NO2tropospheric VCD is less than 25%. The resulting ground-based data set is compared to satellite measurements from the Ozone Monitoring Instrument (OMI) and the Global Ozone Monitoring Experiment-2 (GOME-2). For instance, on 18 July 2011, in an industrial area located at 47.03°N, 22.45°E, GOME-2 observes a tropospheric VCD value of (3.4 ± 1.9) × 1015 molec./cm2, while average mobile measurements in the same area give a value of (3.4 ± 0.7) × 1015 molec./cm2. On 22 August 2011, around Ploiesti city (44.99°N, 26.1°E), the tropospheric VCD observed by satellites is (3.3 ± 1.9) × 1015 molec./cm2 (GOME-2) and (3.2 ± 3.2) × 1015 molec./cm2 (OMI), while average mobile measurements give (3.8 ± 0.8) × 1015 molec./cm2. Average ground measurements over “clean areas”, on 18 July 2011, give (2.5 ± 0.6) × 1015 molec./cm2 while the satellite observes a value of (1.8 ± 1.3) × 1015 molec./cm2. PMID:23519349

EEG entropy measures in anesthesia

PubMed Central

Liang, Zhenhu; Wang, Yinghua; Sun, Xue; Li, Duan; Voss, Logan J.; Sleigh, Jamie W.; Hagihira, Satoshi; Li, Xiaoli

2015-01-01

Highlights: ► Twelve entropy indices were systematically compared in monitoring depth of anesthesia and detecting burst suppression.► Renyi permutation entropy performed best in tracking EEG changes associated with different anesthesia states.► Approximate Entropy and Sample Entropy performed best in detecting burst suppression. Objective: Entropy algorithms have been widely used in analyzing EEG signals during anesthesia. However, a systematic comparison of these entropy algorithms in assessing anesthesia drugs' effect is lacking. In this study, we compare the capability of 12 entropy indices for monitoring depth of anesthesia (DoA) and detecting the burst suppression pattern (BSP), in anesthesia induced by GABAergic agents. Methods: Twelve indices were investigated, namely Response Entropy (RE) and State entropy (SE), three wavelet entropy (WE) measures [Shannon WE (SWE), Tsallis WE (TWE), and Renyi WE (RWE)], Hilbert-Huang spectral entropy (HHSE), approximate entropy (ApEn), sample entropy (SampEn), Fuzzy entropy, and three permutation entropy (PE) measures [Shannon PE (SPE), Tsallis PE (TPE) and Renyi PE (RPE)]. Two EEG data sets from sevoflurane-induced and isoflurane-induced anesthesia respectively were selected to assess the capability of each entropy index in DoA monitoring and BSP detection. To validate the effectiveness of these entropy algorithms, pharmacokinetic/pharmacodynamic (PK/PD) modeling and prediction probability (Pk) analysis were applied. The multifractal detrended fluctuation analysis (MDFA) as a non-entropy measure was compared. Results: All the entropy and MDFA indices could track the changes in EEG pattern during different anesthesia states. Three PE measures outperformed the other entropy indices, with less baseline variability, higher coefficient of determination (R2) and prediction probability, and RPE performed best; ApEn and SampEn discriminated BSP best. Additionally, these entropy measures showed an advantage in computation efficiency compared with MDFA. Conclusion: Each entropy index has its advantages and disadvantages in estimating DoA. Overall, it is suggested that the RPE index was a superior measure. Investigating the advantages and disadvantages of these entropy indices could help improve current clinical indices for monitoring DoA. PMID:25741277

The tilt effect in DOAS observations

NASA Astrophysics Data System (ADS)

Lampel, Johannes; Wang, Yang; Hilboll, Andreas; Beirle, Steffen; Sihler, Holger; Puķīte, Janis; Platt, Ulrich; Wagner, Thomas

2017-12-01

Experience of differential atmospheric absorption spectroscopy (DOAS) shows that a spectral shift between measurement spectra and reference spectra is frequently required in order to achieve optimal fit results, while the straightforward calculation of the optical density proves inferior. The shift is often attributed to temporal instabilities of the instrument but implicitly solved the problem of the tilt effect discussed/explained in this paper. Spectral positions of Fraunhofer and molecular absorption lines are systematically shifted for different measurement geometries due to an overall slope - or tilt - of the intensity spectrum. The phenomenon has become known as the tilt effect for limb satellite observations, where it is corrected for in a first-order approximation, whereas the remaining community is less aware of its cause and consequences. It is caused by the measurement process, because atmospheric absorption and convolution in the spectrometer do not commute. Highly resolved spectral structures in the spectrum will first be modified by absorption and scattering processes in the atmosphere before they are recorded with a spectrometer, which convolves them with a specific instrument function. In the DOAS spectral evaluation process, however, the polynomial (or other function used for this purpose) accounting for broadband absorption is applied after the convolution is performed. In this paper, we derive that changing the order of the two modifications of the spectra leads to different results. Assuming typical geometries for the observations of scattered sunlight and a spectral resolution of 0.6 nm, this effect can be interpreted as a spectral shift of up to 1.5 pm, which is confirmed in the actual analysis of the ground-based measurements of scattered sunlight as well as in numerical radiative transfer simulations. If no spectral shift is allowed by the fitting routine, residual structures of up to 2.5 × 10-3 peak-to-peak are observed. Thus, this effect needs to be considered for DOAS applications aiming at an rms of the residual of 10-3 and below.

Estimates of free-tropospheric NO2 and HCHO mixing ratios derived from high-altitude mountain MAX-DOAS observations at midlatitudes and in the tropics

NASA Astrophysics Data System (ADS)

Schreier, Stefan F.; Richter, Andreas; Wittrock, Folkard; Burrows, John P.

2016-03-01

In this study, mixing ratios of NO2 (XNO2) and HCHO (XHCHO) in the free troposphere are derived from two multi-axis differential optical absorption spectroscopy (MAX-DOAS) data sets collected at Zugspitze (2650 m a.s.l., Germany) and Pico Espejo (4765 m a.s.l., Venezuela). The estimation of NO2 and HCHO mixing ratios is based on the modified geometrical approach, which assumes a single-scattering geometry and a scattering point altitude close to the instrument altitude. Firstly, the horizontal optical path length (hOPL) is obtained from O4 differential slant column densities (DSCDs) in the horizontal (0°) and vertical (90°) viewing directions. Secondly, XNO2 and XHCHO are estimated from the NO2 and HCHO DSCDs at the 0° and 90° viewing directions and averaged along the obtained hOPLs. As the MAX-DOAS instrument was performing measurements in the ultraviolet region, wavelength ranges of 346-372 and 338-357 nm are selected for the DOAS analysis to retrieve NO2 and HCHO DSCDs, respectively. In order to compare the measured O4 DSCDs and moreover to perform some sensitivity tests, the radiative transfer model SCIATRAN with adapted altitude settings for mountainous terrain is operated to simulate synthetic spectra, on which the DOAS analysis is also applied. The overall agreement between measured and synthetic O4 DSCDs is better for the higher Pico Espejo station than for Zugspitze. Further sensitivity analysis shows that a change in surface albedo (from 0.05 to 0.7) can influence the O4 DSCDs, with a larger absolute difference observed for the horizontal viewing direction. Consequently, the hOPL can vary by about 5 % throughout the season, for example when winter snow cover fully disappears in summer. Typical values of hOPLs during clear-sky conditions are 19 km (14 km) at Zugspitze and 34 km (26.5 km) at Pico Espejo when using the 346-372 (338-357 nm) fitting window. The estimated monthly values of XNO2 (XHCHO), averaged over these hOPLs during clear-sky conditions, are in the range of 60-100 ppt (500-950 ppt) at Zugspitze and 8.5-15.5 ppt (255-385 ppt) at Pico Espejo. Interestingly, multi-year-averaged monthly means of XNO2 and XHCHO increase towards the end of the dry season at the Pico Espejo site, suggesting that both trace gases are frequently lifted above the boundary layer as a result of South American biomass burning.

Estimates of free-tropospheric NO2 and HCHO mixing ratios derived from high-altitude mountain MAX-DOAS observations in the mid-latitudes and tropics

NASA Astrophysics Data System (ADS)

Schreier, S. F.; Richter, A.; Wittrock, F.; Burrows, J. P.

2015-11-01

In this study, mixing ratios of NO2 (XNO2) and HCHO (XHCHO) in the free troposphere are derived from two Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) data sets collected at Zugspitze (2650 m a.s.l., Germany) and Pico Espejo (4765 m a.s.l., Venezuela). The estimation of NO2 and HCHO mixing ratios is based on the modified geometrical approach, which assumes a single-scattering geometry and a scattering point altitude close to the instrument. Firstly, the horizontal optical path length (hOPL) is obtained from O4 differential slant column densities (DSCDs) in the horizontal (0°) and vertical (90°) viewing directions. Secondly, XNO2 and XHCHO are estimated from the NO2 and HCHO DSCDs at the 0 and 90° viewing directions and averaged along the obtained hOPLs. As the MAX-DOAS instrument was performing measurements in the ultraviolet region, wavelength ranges of 346-372 and 338-357 nm are selected for the DOAS analysis to retrieve NO2 and HCHO DSCDs, respectively. In order to compare the measured O4 DSCDs and moreover to perform some sensitivity tests, the radiative transfer model SCIATRAN with adapted altitude settings for mountainous terrain is operated to simulate synthetic spectra, on which the DOAS analysis is also applied. The overall agreement between measured and synthetic O4 DSCDs is better for the higher Pico Espejo station than for Zugspitze. Further sensitivity analysis shows that a change in surface albedo (from 0.05 to 0.7) can influence the O4 DSCDs, with a larger absolute difference observed for the horizontal viewing direction. Consequently, the hOPL can vary by about 5 % throughout the season, for example when winter snow cover fully disappears in summer. Typical values of hOPLs during clear sky conditions are 19 km (14 km) at Zugspitze and 34 km (26.5 km) at Pico Espejo when using the 346-372 nm (338-357 nm) fitting window. The estimated monthly values of XNO2 (XHCHO), averaged over these hOPLs during clear sky conditions, are in the range of 60-100 ppt (500-950 ppt) at Zugspitze and 8.5-15.5 ppt (255-385 ppt) at Pico Espejo. Interestingly, multi-year averaged monthly means of XNO2 and XHCHO increase towards the end of the dry season at the Pico Espejo site, suggesting that both trace gases are frequently lifted above the boundary layer as a result of South American biomass burning.

Accounting for surface reflectance in the derivation of vertical column densities of NO2 from airborne imaging DOAS

NASA Astrophysics Data System (ADS)

Meier, Andreas Carlos; Schönhardt, Anja; Richter, Andreas; Bösch, Tim; Seyler, André; Constantin, Daniel Eduard; Shaiganfar, Reza; Merlaud, Alexis; Ruhtz, Thomas; Wagner, Thomas; van Roozendael, Michel; Burrows, John. P.

2016-04-01

Nitrogen oxides, NOx (NOx = NO + NO2) play a key role in tropospheric chemistry. In addition to their directly harmful effects on the respiratory system of living organisms, they influence the levels of tropospheric ozone and contribute to acid rain and eutrophication of ecosystems. As they are produced in combustion processes, they can serve as an indicator for anthropogenic air pollution. In the late summers of 2014 and 2015, two extensive measurement campaigns were conducted in Romania by several European research institutes, with financial support from ESA. The AROMAT / AROMAT-2 campaigns (Airborne ROmanian Measurements of Aerosols and Trace gases) were dedicated to measurements of air quality parameters utilizing newly developed instrumentation at state-of-the-art. The experiences gained will help to calibrate and validate the measurements taken by the upcoming Sentinel-S5p mission scheduled for launch in 2016. The IUP Bremen contributed to these campaigns with its airborne imaging DOAS (Differential Optical Absorption Spectroscopy) instrument AirMAP (Airborne imaging DOAS instrument for Measurements of Atmospheric Pollution). AirMAP allows retrieving spatial distributions of trace gas columns densities in a stripe below the aircraft. The measurements have a high spatial resolution of approximately 30 x 80 m2 (along x across track) at a typical flight altitude of 3000 m. Supported by the instrumental setup and the large swath, gapless maps of trace gas distributions above a large city, like Bucharest or Berlin, can be acquired within a time window of approximately two hours. These properties make AirMAP a valuable tool for the validation of trace gas measurements from space. DOAS retrievals yield the density of absorbers integrated along the light path of the measurement. The light path is altered with a changing surface reflectance, leading to enhanced / reduced slant column densities of NO2 depending on surface properties. This effect must be considered in the derivation of air mass factors used to convert the measurements into vertical columns. Due to the high-resolution measurements, no data product of surface reflectance with sufficient spatial resolution is available. Thus the surface reflectance is estimated from AirMAP's own spectra. In this work the results of the research flights will be presented. The study focuses on the validation of AirMAP's measurements by comparison to other ground-based platforms like (mobile) MAX-DOAS measurements. Conclusions will be drawn on the quality of the measurements, their applicability for satellite data validation and possible improvements for future measurements.

Design of Small MEMS Microphone Array Systems for Direction Finding of Outdoors Moving Vehicles

PubMed Central

Zhang, Xin; Huang, Jingchang; Song, Enliang; Liu, Huawei; Li, Baoqing; Yuan, Xiaobing

2014-01-01

In this paper, a MEMS microphone array system scheme is proposed which implements real-time direction of arrival (DOA) estimation for moving vehicles. Wind noise is the primary source of unwanted noise on microphones outdoors. A multiple signal classification (MUSIC) algorithm is used in this paper for direction finding associated with spatial coherence to discriminate between the wind noise and the acoustic signals of a vehicle. The method is implemented in a SHARC DSP processor and the real-time estimated DOA is uploaded through Bluetooth or a UART module. Experimental results in different places show the validity of the system and the deviation is no bigger than 6° in the presence of wind noise. PMID:24603636

Design of small MEMS microphone array systems for direction finding of outdoors moving vehicles.

PubMed

Zhang, Xin; Huang, Jingchang; Song, Enliang; Liu, Huawei; Li, Baoqing; Yuan, Xiaobing

2014-03-05

In this paper, a MEMS microphone array system scheme is proposed which implements real-time direction of arrival (DOA) estimation for moving vehicles. Wind noise is the primary source of unwanted noise on microphones outdoors. A multiple signal classification (MUSIC) algorithm is used in this paper for direction finding associated with spatial coherence to discriminate between the wind noise and the acoustic signals of a vehicle. The method is implemented in a SHARC DSP processor and the real-time estimated DOA is uploaded through Bluetooth or a UART module. Experimental results in different places show the validity of the system and the deviation is no bigger than 6° in the presence of wind noise.

Regional robust stabilisation and domain-of-attraction estimation for MIMO uncertain nonlinear systems with input saturation

NASA Astrophysics Data System (ADS)

Azizi, S.; Torres, L. A. B.; Palhares, R. M.

2018-01-01

The regional robust stabilisation by means of linear time-invariant state feedback control for a class of uncertain MIMO nonlinear systems with parametric uncertainties and control input saturation is investigated. The nonlinear systems are described in a differential algebraic representation and the regional stability is handled considering the largest ellipsoidal domain-of-attraction (DOA) inside a given polytopic region in the state space. A novel set of sufficient Linear Matrix Inequality (LMI) conditions with new auxiliary decision variables are developed aiming to design less conservative linear state feedback controllers with corresponding larger DOAs, by considering the polytopic description of the saturated inputs. A few examples are presented showing favourable comparisons with recently published similar control design methodologies.

Alternative Fuels Data Center

Science.gov Websites

Volkswagen Settlement Allocation The Wisconsin Department of Administration (DOA) may use funds awarded to Wisconsin through the Volkswagen Clean Air Act Civil Settlement (Settlement) to replace

Eleven years of tropospheric NO2 measured by GOME, SCIAMACHY and OMI

NASA Astrophysics Data System (ADS)

Eskes, H.; Boersma, F.; Dirksen, R.; van der A, R.; Veefkind, P.; Levelt, P.; Brinksma, E.; van Roozendael, M.; de Smedt, I.; Gleason, J.

2006-12-01

Based on measurements of GOME on ESA ERS-2, SCIAMACHY on ESA-ENVISAT, and Ozone Monitoring Instrument (OMI) on the NASA EOS-Aura satellite there is now a unique 11-year dataset of global tropospheric nitrogen dioxide measurements from space. The retrieval approach consists of two steps. The first step is an application of the DOAS (Differential Optical Absorption Spectroscopy) approach which delivers the total absorption optical thickness along the light path (the slant column). For GOME and SCIAMACHY this is based on the DOAS implementation developed by BIRA/IASB. For OMI the DOAS implementation was developed in a collaboration between KNMI and NASA. The second retrieval step, developed at KNMI, estimates the tropospheric vertical column of NO2 based on the slant column, cloud fraction and cloud top height retrieval, stratospheric column estimates derived from a data assimilation approach and vertical profile estimates from space-time collocated profiles from the TM chemistry-transport model. The second step was applied with only minor modifications to all three instruments to generate a uniform 11-year data set. In our talk we will address the following topics: - A short summary of the retrieval approach and results - Comparisons with other retrievals - Comparisons with global and regional-scale models - OMI-SCIAMACHY and SCIAMACHY-GOME comparisons - Validation with independent measurements - Trend studies of NO2 for the past 11 years

Toward Quantitative Estimation of the Effect of Aerosol Particles in the Global Climate Model and Cloud Resolving Model

NASA Astrophysics Data System (ADS)

Eskes, H.; Boersma, F.; Dirksen, R.; van der A, R.; Veefkind, P.; Levelt, P.; Brinksma, E.; van Roozendael, M.; de Smedt, I.; Gleason, J.

2005-05-01

Based on measurements of GOME on ESA ERS-2, SCIAMACHY on ESA-ENVISAT, and Ozone Monitoring Instrument (OMI) on the NASA EOS-Aura satellite there is now a unique 11-year dataset of global tropospheric nitrogen dioxide measurements from space. The retrieval approach consists of two steps. The first step is an application of the DOAS (Differential Optical Absorption Spectroscopy) approach which delivers the total absorption optical thickness along the light path (the slant column). For GOME and SCIAMACHY this is based on the DOAS implementation developed by BIRA/IASB. For OMI the DOAS implementation was developed in a collaboration between KNMI and NASA. The second retrieval step, developed at KNMI, estimates the tropospheric vertical column of NO2 based on the slant column, cloud fraction and cloud top height retrieval, stratospheric column estimates derived from a data assimilation approach and vertical profile estimates from space-time collocated profiles from the TM chemistry-transport model. The second step was applied with only minor modifications to all three instruments to generate a uniform 11-year data set. In our talk we will address the following topics: - A short summary of the retrieval approach and results - Comparisons with other retrievals - Comparisons with global and regional-scale models - OMI-SCIAMACHY and SCIAMACHY-GOME comparisons - Validation with independent measurements - Trend studies of NO2 for the past 11 years

Loss of functional OPA1 unbalances redox state: implications in dominant optic atrophy pathogenesis.

PubMed

Millet, Aurélie M C; Bertholet, Ambre M; Daloyau, Marlène; Reynier, Pascal; Galinier, Anne; Devin, Anne; Wissinguer, Bernd; Belenguer, Pascale; Davezac, Noélie

2016-06-01

OPA1 mutations cause protein haploinsufficiency leading to dominant optic atrophy (DOA), an incurable retinopathy with variable severity. Up to 20% of patients also develop extraocular neurological complications. The mechanisms that cause this optic atrophy or its syndromic forms are still unknown. After identifying oxidative stress in a mouse model of the pathology, we sought to determine the consequences of OPA1 dysfunction on redox homeostasis. Mitochondrial respiration, reactive oxygen species levels, antioxidant defenses, and cell death were characterized by biochemical and in situ approaches in both in vitro and in vivo models of OPA1 haploinsufficiency. A decrease in aconitase activity suggesting an increase in reactive oxygene species and an induction of antioxidant defenses was observed in cortices of a murine model as well as in OPA1 downregulated cortical neurons. This increase is associated with a decline in mitochondrial respiration in vitro. Upon exogenous oxidative stress, OPA1-depleted neurons did not further exhibit upregulated antioxidant defenses but were more sensitive to cell death. Finally, low levels of antioxidant enzymes were found in fibroblasts from patients supporting their role as modifier factors. Our study suggests that the pro-oxidative state induced by OPA1 loss may contribute to DOA pathogenesis and that differences in antioxidant defenses can explain the variability in expressivity. Furthermore, antioxidants may be used as therapy as they could prevent or delay DOA symptoms in patients.

Flux Calculation Using CARIBIC DOAS Aircraft Measurements: SO2 Emission of Norilsk

NASA Technical Reports Server (NTRS)

Walter, D.; Heue, K.-P.; Rauthe-Schoech, A.; Brenninkmeijer, C. A. M.; Lamsal, L. N.; Krotkov, N. A.; Platt, U.

2012-01-01

Based on a case-study of the nickel smelter in Norilsk (Siberia), the retrieval of trace gas fluxes using airborne remote sensing is discussed. A DOAS system onboard an Airbus 340 detected large amounts of SO2 and NO2 near Norilsk during a regular passenger flight within the CARIBIC project. The remote sensing data were combined with ECMWF wind data to estimate the SO2 output of the Norilsk industrial complex to be around 1 Mt per year, which is in agreement with independent estimates. This value is compared to results using data from satellite remote sensing (GOME, OMI). The validity of the assumptions underlying our estimate is discussed, including the adaptation of this method to other gases and sources like the NO2 emissions of large industries or cities.

The CU 2-D-MAX-DOAS instrument – Part 2: Raman scattering probability measurements and retrieval of aerosol optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortega, Ivan; Coburn, Sean; Berg, Larry K.

The multiannual global mean of aerosol optical depth at 550 nm (AOD 550) over land is ~0.19, and that over oceans is ~0.13. About 45 % of the Earth surface shows AOD 550 smaller than 0.1. There is a need for measurement techniques that are optimized to measure aerosol optical properties under low AOD conditions. We present an inherently calibrated retrieval (i.e., no need for radiance calibration) to simultaneously measure AOD and the aerosol phase function parameter, g, based on measurements of azimuth distributions of the Raman scattering probability (RSP), the near-absolute rotational Raman scattering (RRS) intensity. We employ radiativemore » transfer model simulations to show that for solar azimuth RSP measurements at solar elevation and solar zenith angle (SZA) smaller than 80°, RSP is insensitive to the vertical distribution of aerosols and maximally sensitive to changes in AOD and g under near-molecular scattering conditions. The University of Colorado two-dimensional Multi-AXis Differential Optical Absorption Spectroscopy (CU 2-D-MAX-DOAS) instrument was deployed as part of the Two Column Aerosol Project (TCAP) at Cape Cod, MA, during the summer of 2012 to measure direct sun spectra and RSP from scattered light spectra at solar relative azimuth angles (SRAAs) between 5 and 170°. During two case study days with (1) high aerosol load (17 July, 0.3 < AOD 430 < 0.6) and (2) near-molecular scattering conditions (22 July, AOD 430 < 0.13) we compare RSP-based retrievals of AOD 430 and g with data from a co-located CIMEL sun photometer, Multi-Filter Rotating Shadowband Radiometer (MFRSR), and an airborne High Spectral Resolution Lidar (HSRL-2). The average difference (relative to DOAS) for AOD 430 is +0.012 ± 0.023 (CIMEL), -0.012 ± 0.024 (MFRSR), -0.011 ± 0.014 (HSRL-2), and +0.023 ± 0.013 (CIMEL AOD - MFRSR AOD) and yields the following expressions for correlations between different instruments: DOAS AOD = - (0.019 ± 0.006) + (1.03 ± 0.02)×CIMEL AOD ( R 2 = 0.98), DOAS AOD = -(0.006 ± 0.005)+(1.08 ± 0.02)×MFRSR AOD ( R 2 = 0.98), and CIMEL AOD=(0.013 ± 0.004)+(1.05 ± 0.01)× MFRSR AOD ( R 2=0.99). The average g measured by DOAS on both days was 0.66 ± 0.03, with a difference of 0.014 ± 0.05 compared to CIMEL. Active steps to minimize the error in the RSP help to reduce the uncertainty in retrievals of AOD and g. As AOD decreases and SZA increases, the RSP signal-to-noise ratio increases. At AOD 430 ~ 0.4 and 0.10 the absolute AOD errors are ~ 0.014 and 0.003 at 70° SZA and 0.02 and 0.004 at 35°SZA. Inherently calibrated, precise AOD and g measurements are useful to better characterize the aerosol direct effect in urban polluted and remote pristine environments.« less

The CU 2-D-MAX-DOAS instrument – Part 2: Raman scattering probability measurements and retrieval of aerosol optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortega, Ivan; Coburn, Sean; Berg, Larry K.

In this study, the multiannual global mean of aerosol optical depth at 550 nm (AOD 550) over land is ~0.19, and that over oceans is ~0.13. About 45 % of the Earth surface shows AOD 550 smaller than 0.1. There is a need for measurement techniques that are optimized to measure aerosol optical properties under low AOD conditions. We present an inherently calibrated retrieval (i.e., no need for radiance calibration) to simultaneously measure AOD and the aerosol phase function parameter, g, based on measurements of azimuth distributions of the Raman scattering probability (RSP), the near-absolute rotational Raman scattering (RRS) intensity.more » We employ radiative transfer model simulations to show that for solar azimuth RSP measurements at solar elevation and solar zenith angle (SZA) smaller than 80°, RSP is insensitive to the vertical distribution of aerosols and maximally sensitive to changes in AOD and g under near-molecular scattering conditions. The University of Colorado two-dimensional Multi-AXis Differential Optical Absorption Spectroscopy (CU 2-D-MAX-DOAS) instrument was deployed as part of the Two Column Aerosol Project (TCAP) at Cape Cod, MA, during the summer of 2012 to measure direct sun spectra and RSP from scattered light spectra at solar relative azimuth angles (SRAAs) between 5 and 170°. During two case study days with (1) high aerosol load (17 July, 0.3 < AOD 430 < 0.6) and (2) near-molecular scattering conditions (22 July, AOD 430 < 0.13) we compare RSP-based retrievals of AOD 430 and g with data from a co-located CIMEL sun photometer, Multi-Filter Rotating Shadowband Radiometer (MFRSR), and an airborne High Spectral Resolution Lidar (HSRL-2). The average difference (relative to DOAS) for AOD 430 is +0.012 ± 0.023 (CIMEL), –0.012 ± 0.024 (MFRSR), –0.011 ± 0.014 (HSRL-2), and +0.023 ± 0.013 (CIMEL AOD –MFRSR AOD) and yields the following expressions for correlations between different instruments: DOAS AOD = –(0.019 ± 0.006) + (1.03 ± 0.02) × CIMEL AOD ( R 2 = 0.98), DOAS AOD = –(0.006 ± 0.005) + (1.08 ± 0.02) × MFRSR AOD ( R 2 = 0.98), and CIMEL AOD = (0.013 ± 0.004) + (1.05 ± 0.01) × MFRSR AOD ( R 2 = 0.99). The average g measured by DOAS on both days was 0.66 ± 0.03, with a difference of 0.014 ± 0.05 compared to CIMEL. Active steps to minimize the error in the RSP help to reduce the uncertainty in retrievals of AOD and g. As AOD decreases and SZA increases, the RSP signal-to-noise ratio increases. At AOD 430 ~0.4 and 0.10 the absolute AOD errors are ~ 0.014 and 0.003 at 70° SZA and 0.02 and 0.004 at 35° SZA. Inherently calibrated, precise AOD and g measurements are useful to better characterize the aerosol direct effect in urban polluted and remote pristine environments.« less

The CU 2-D-MAX-DOAS instrument – Part 2: Raman scattering probability measurements and retrieval of aerosol optical properties

DOE PAGES

Ortega, Ivan; Coburn, Sean; Berg, Larry K.; ...

2016-08-23

In this study, the multiannual global mean of aerosol optical depth at 550 nm (AOD 550) over land is ~0.19, and that over oceans is ~0.13. About 45 % of the Earth surface shows AOD 550 smaller than 0.1. There is a need for measurement techniques that are optimized to measure aerosol optical properties under low AOD conditions. We present an inherently calibrated retrieval (i.e., no need for radiance calibration) to simultaneously measure AOD and the aerosol phase function parameter, g, based on measurements of azimuth distributions of the Raman scattering probability (RSP), the near-absolute rotational Raman scattering (RRS) intensity.more » We employ radiative transfer model simulations to show that for solar azimuth RSP measurements at solar elevation and solar zenith angle (SZA) smaller than 80°, RSP is insensitive to the vertical distribution of aerosols and maximally sensitive to changes in AOD and g under near-molecular scattering conditions. The University of Colorado two-dimensional Multi-AXis Differential Optical Absorption Spectroscopy (CU 2-D-MAX-DOAS) instrument was deployed as part of the Two Column Aerosol Project (TCAP) at Cape Cod, MA, during the summer of 2012 to measure direct sun spectra and RSP from scattered light spectra at solar relative azimuth angles (SRAAs) between 5 and 170°. During two case study days with (1) high aerosol load (17 July, 0.3 < AOD 430 < 0.6) and (2) near-molecular scattering conditions (22 July, AOD 430 < 0.13) we compare RSP-based retrievals of AOD 430 and g with data from a co-located CIMEL sun photometer, Multi-Filter Rotating Shadowband Radiometer (MFRSR), and an airborne High Spectral Resolution Lidar (HSRL-2). The average difference (relative to DOAS) for AOD 430 is +0.012 ± 0.023 (CIMEL), –0.012 ± 0.024 (MFRSR), –0.011 ± 0.014 (HSRL-2), and +0.023 ± 0.013 (CIMEL AOD –MFRSR AOD) and yields the following expressions for correlations between different instruments: DOAS AOD = –(0.019 ± 0.006) + (1.03 ± 0.02) × CIMEL AOD ( R 2 = 0.98), DOAS AOD = –(0.006 ± 0.005) + (1.08 ± 0.02) × MFRSR AOD ( R 2 = 0.98), and CIMEL AOD = (0.013 ± 0.004) + (1.05 ± 0.01) × MFRSR AOD ( R 2 = 0.99). The average g measured by DOAS on both days was 0.66 ± 0.03, with a difference of 0.014 ± 0.05 compared to CIMEL. Active steps to minimize the error in the RSP help to reduce the uncertainty in retrievals of AOD and g. As AOD decreases and SZA increases, the RSP signal-to-noise ratio increases. At AOD 430 ~0.4 and 0.10 the absolute AOD errors are ~ 0.014 and 0.003 at 70° SZA and 0.02 and 0.004 at 35° SZA. Inherently calibrated, precise AOD and g measurements are useful to better characterize the aerosol direct effect in urban polluted and remote pristine environments.« less

Genetic Screening for OPA1 and OPA3 Mutations in Patients with Suspected Inherited Optic Neuropathies

PubMed Central

Yu-Wai-Man, Patrick; Shankar, Suma P.; Biousse, Valérie; Miller, Neil R.; Bean, Lora J.H.; Coffee, Bradford; Hegde, Madhuri; Newman, Nancy J.

2010-01-01

Purpose Autosomal-dominant optic atrophy (DOA) is one of the most common inherited optic neuropathies, and it is genetically heterogeneous, with mutations in both OPA1 and OPA3 known to cause disease. About 60% of cases harbor OPA1 mutations, whereas OPA3 mutations have only been reported in two pedigrees with DOA and premature cataracts. The aim of this study was to determine the yield of OPA1 and OPA3 screening in a cohort of presumed DOA cases referred to a tertiary diagnostic laboratory. Design Retrospective case series. Participants One hundred and eighty-eight probands with bilateral optic atrophy referred for molecular genetic investigations at a tertiary diagnostic facility: 38 patients with an autosomal-dominant pattern of inheritance and 150 sporadic cases. Methods OPA1 and OPA3 genetic testing was initially performed using PCR-based sequencing methods. The presence of large-scale OPA1 and OPA3 genomic rearrangements was further assessed with a targeted comparative genomic hybridization (CGH) microarray platform. The three primary Leber hereditary optic neuropathy (LHON) mutations, m.3460G>A, m.11778G>A, and m.14484T>C, were also screened in all patients. Main Outcome Measures The proportion of patients with OPA1 and OPA3 pathogenic mutations. The clinical profile observed in molecularly confirmed DOA cases. Results We found 21 different OPA1 mutations in 27 of the 188 (14.4%) probands screened. The mutations included six novel pathogenic variants and the first reported OPA1 initiation codon mutation at c.1A>T. An OPA1 missense mutation, c.239A>G (p.Y80C), was identified in an 11-year-old African-American girl with optic atrophy and peripheral sensori-motor neuropathy in her lower limbs. The OPA1 detection rate was significantly higher among individuals with a positive family history of visual failure (50.0%) compared with sporadic cases (5.3%). The primary LHON screen was negative in our patient cohort, and additional molecular investigations did not reveal any large-scale OPA1 rearrangements or OPA3 genetic defects. The mean baseline visual acuity for our OPA1-positive group was 0.48 logarithm of the minimum angle of resolution (LogMAR) (Mean Snellen equivalent = 20/61, range = 20/20–20/400, 95% confidence interval = 20/52–20/71), and visual deterioration occurred in 54.2% of patients during follow-up. Conclusions OPA1 mutations are the most common genetic defects identified in patients with suspected DOA, whereas OPA3 mutations are very rare in isolated optic atrophy cases. PMID:21036400

Effects of anabolic implants and ractopamine-HCl on muscle fiber morphometrics, collagen solubility, and tenderness of beef longissimus lumborum steaks.

PubMed

Ebarb, S M; Phelps, K J; Drouillard, J S; Maddock-Carlin, K R; Vaughn, M A; Burnett, D D; Noel, J A; Van Bibber-Krueger, C L; Paulk, C B; Grieger, D M; Gonzalez, J M

2017-03-01

The objective of this study was to examine the effects of growth-promoting technologies (GP) and postmortem aging on longissimus lumborum muscle fiber cross-sectional area (CSA), collagen solubility, and their relationship to meat tenderness. Two groups of black-hided crossbred feedlot heifers (group 1: = 33, initial BW 430 ± 7 kg; group 2: = 32, initial BW 466 ± 7 kg) were blocked by BW and assigned to 1 of 3 treatments consisting of: no implant and no ractopamine hydrochloride (CON; = 21); implant, no ractopamine hydrochloride (IMP; = 22); implant and ractopamine hydrochloride (COMBO; = 22). Heifers that received an implant were administered an implant containing 200 mg trenbolone acetate and 20 mg estradiol on d 0 of the study, and heifers in the COMBO group received 400 mg∙head∙d of ractopamine hydrochloride for 28 (Group 1) or 29 d (Group 2) at the end of 90- (Group 1) or 106-d (Group 2) feeding period. Following harvest, strip loins were collected and further fabricated into 5 roasts for postmortem aging (DOA) periods of 2, 7, 14, 21, or 35 d. After aging, Warner-Bratzler shear force (WBSF), muscle fiber CSA, and collagen solubility were measured. There was no treatment × DOA interaction for WBSF ( = 0.86), but treatment and DOA impacted WBSF ( < 0.01). Over the entire aging study, COMBO steaks had greater ( < 0.01) shear force values when compared to CON steaks. The IMP steaks tended to have decreased ( = 0.07) shear force when compared to the COMBO steaks, but did not differ ( = 0.11) from CON steaks. The IMP and COMBO treatments had increased type IIA fiber CSA when compared to CON ( < 0.01). When compared to each other, the IMP and COMBO type IIA fiber CSA did not differ ( = 0.76). Type I and IIX fiber CSA tended to be greater than CON for IMP and COMBO treatments ( < 0.10). There was no treatment × DOA interaction for all collagen measures ( > 0.33). Collagen amounts were not impacted by GP treatment ( > 0.72), but DOA increased the concentration of soluble collagen ( = 0.04). Fiber CSA of all fiber types were positively correlated ( < 0.05; = 0.21 to 0.28) with WBSF only on d 2 of aging, while soluble collagen amount tended to negatively correlate with WBSF on d 7 and 14 of aging ( < 0.10; = -0.24 and -0.23, respectively). Administration of GP during heifer finishing resulted in greater steak WBSF over 35 d of aging, which was not due to collagen characteristics and only minimally affected by fiber CSA.

Sample entropy analysis for the estimating depth of anaesthesia through human EEG signal at different levels of unconsciousness during surgeries

PubMed Central

Fan, Shou-Zen; Abbod, Maysam F.

2018-01-01

Estimating the depth of anaesthesia (DoA) in operations has always been a challenging issue due to the underlying complexity of the brain mechanisms. Electroencephalogram (EEG) signals are undoubtedly the most widely used signals for measuring DoA. In this paper, a novel EEG-based index is proposed to evaluate DoA for 24 patients receiving general anaesthesia with different levels of unconsciousness. Sample Entropy (SampEn) algorithm was utilised in order to acquire the chaotic features of the signals. After calculating the SampEn from the EEG signals, Random Forest was utilised for developing learning regression models with Bispectral index (BIS) as the target. Correlation coefficient, mean absolute error, and area under the curve (AUC) were used to verify the perioperative performance of the proposed method. Validation comparisons with typical nonstationary signal analysis methods (i.e., recurrence analysis and permutation entropy) and regression methods (i.e., neural network and support vector machine) were conducted. To further verify the accuracy and validity of the proposed methodology, the data is divided into four unconsciousness-level groups on the basis of BIS levels. Subsequently, analysis of variance (ANOVA) was applied to the corresponding index (i.e., regression output). Results indicate that the correlation coefficient improved to 0.72 ± 0.09 after filtering and to 0.90 ± 0.05 after regression from the initial values of 0.51 ± 0.17. Similarly, the final mean absolute error dramatically declined to 5.22 ± 2.12. In addition, the ultimate AUC increased to 0.98 ± 0.02, and the ANOVA analysis indicates that each of the four groups of different anaesthetic levels demonstrated significant difference from the nearest levels. Furthermore, the Random Forest output was extensively linear in relation to BIS, thus with better DoA prediction accuracy. In conclusion, the proposed method provides a concrete basis for monitoring patients’ anaesthetic level during surgeries. PMID:29844970

Incorporation of a selective sigma-2 receptor ligand enhances uptake of liposomes by multiple cancer cells

PubMed Central

Zhang, Yifei; Huang, Yixian; Zhang, Peng; Gao, Xiang; Gibbs, Robert B; Li, Song

2012-01-01

Background: The sigma-2 receptor is an attractive target for tumor imaging and targeted therapy because it is overexpressed in multiple types of solid tumors, including prostate cancer, breast cancer, and lung cancer. SV119 is a synthetic small molecule that binds to sigma-2 receptors with high affinity and specificity. This study investigates the utility of SV119 in mediating the selective targeting of liposomal vectors in various types of cancer cells. Methods: SV119 was covalently linked with polyethylene glycol-dioleyl amido aspartic acid conjugate (PEG-DOA) to generate a novel functional lipid, SV119-PEG-DOA. This lipid was utilized for the preparation of targeted liposomes to enhance their uptake by cancer cells. Liposomes with various SV119 densities (0, 1, 3, and 5 mole%) were prepared and their cellular uptake was investigated in several tumor cell lines. In addition, doxorubicin (DOX) was loaded into the targeted and unmodified liposomes, and the cytotoxic effect on the DU-145 cells was evaluated by MTT assay. Results: Liposomes with or without SV119-PEG-DOA both have a mean diameter of approximately 90 nm and a neutral charge. The incorporation of SV119-PEG-DOA significantly increased the cellular uptake of liposomes by the DU-145, PC-3, A549, 201T, and MCF-7 tumor cells, which was shown by fluorescence microscopy and the quantitative measurement of fluorescence intensity. In contrast, the incorporation of SV119 did not increase the uptake of liposomes by the normal BEAS-2B cells. In a time course study, the uptake of SV119 liposomes by DU-145 cells was also significantly higher at each time point compared to the unmodified liposomes. Furthermore, the DOX-loaded SV119 liposomes showed significantly higher cytotoxicity to DU-145 cells compared to the DOX-loaded unmodified liposomes. Conclusion: SV119 liposomes were developed for targeted drug delivery to cancer cells. The targeting efficiency and specificity of SV119 liposomes to cancer cells was demonstrated in vitro. The results of this study suggest that SV119-modified liposomes might be a promising drug carrier for tumor-targeted delivery. PMID:22927761

ComPAQS: a compact concentric UV/visible spectrometer, providing a new tool for air quality monitoring from space

NASA Astrophysics Data System (ADS)

Leigh, Roland J.; Whyte, C.; Cutter, M. A.; Lobb, D. R.; Monks, P. S.

2017-11-01

Under the first phase of the Centre for Earth Observation Instrumentation (CEOI), a breadboard demonstrator of a novel UV/VIS spectrometer has been developed. Using designs from Surrey Satellite Technology Ltd (SSTL) the demonstrator has been constructed and tested at the University of Leicester's Space Research Centre. This spectrometer provides an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. Measurement of atmo spheric compounds with climate change or air quality implications is a key driver for the ground and space-based Earth Observation communities. Techniques using UV/VIS spectroscopy such as DOAS provide measurements of ozone profiles, aerosol optical depth, certain Volatile Organic Compounds, halogenated species, and key air quality parameters including tropospheric nitrogen dioxide. Compact instruments providing the necessary optical performance and spectral resolution are therefore a key enabling technology. The Compact Air Quality Spectrometer (CompAQS) features a concentric arrangement of a spherical meniscus lens, a concave spherical mirror and a suitable curved diffraction grating. This compact design provides efficiency and performance benefits over traditional concepts, improving the precision and spatial resolution available from space borne instruments with limited weight and size budgets. The breadboard spectrometer currently operating at the University of Leicester offers high throughput with a spectral range from 310 to 450 nm at 0.5nm(UV) to 1.0nm (visible) resolution, suitable for DOAS applications. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called `smile' - the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. In this presentation, the design of the spectrometer is detailed, with results from instrument characterisations undertaken at the University of Leicester, including demonstrations of DOAS fits for key air quality species.

High-resolution airborne imaging DOAS measurements of NO2 above Bucharest during AROMAT

NASA Astrophysics Data System (ADS)

Meier, Andreas Carlos; Schönhardt, Anja; Bösch, Tim; Richter, Andreas; Seyler, André; Ruhtz, Thomas; Constantin, Daniel-Eduard; Shaiganfar, Reza; Wagner, Thomas; Merlaud, Alexis; Van Roozendael, Michel; Belegante, Livio; Nicolae, Doina; Georgescu, Lucian; Burrows, John Philip

2017-05-01

In this study we report on airborne imaging DOAS measurements of NO2 from two flights performed in Bucharest during the AROMAT campaign (Airborne ROmanian Measurements of Aerosols and Trace gases) in September 2014. These measurements were performed with the Airborne imaging Differential Optical Absorption Spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP) and provide nearly gapless maps of column densities of NO2 below the aircraft with a high spatial resolution of better than 100 m. The air mass factors, which are needed to convert the measured differential slant column densities (dSCDs) to vertical column densities (VCDs), have a strong dependence on the surface reflectance, which has to be accounted for in the retrieval. This is especially important for measurements above urban areas, where the surface properties vary strongly. As the instrument is not radiometrically calibrated, we have developed a method to derive the surface reflectance from intensities measured by AirMAP. This method is based on radiative transfer calculation with SCIATRAN and a reference area for which the surface reflectance is known. While surface properties are clearly apparent in the NO2 dSCD results, this effect is successfully corrected for in the VCD results. Furthermore, we investigate the influence of aerosols on the retrieval for a variety of aerosol profiles that were measured in the context of the AROMAT campaigns. The results of two research flights are presented, which reveal distinct horizontal distribution patterns and strong spatial gradients of NO2 across the city. Pollution levels range from background values in the outskirts located upwind of the city to about 4 × 1016 molec cm-2 in the polluted city center. Validation against two co-located mobile car-DOAS measurements yields good agreement between the datasets, with correlation coefficients of R = 0.94 and R = 0.85, respectively. Estimations on the NOx emission rate of Bucharest for the two flights yield emission rates of 15.1 ± 9.4 and 13.6 ± 8.4 mol s-1, respectively.

Spatial aliasing for efficient direction-of-arrival estimation based on steering vector reconstruction

NASA Astrophysics Data System (ADS)

Yan, Feng-Gang; Cao, Bin; Rong, Jia-Jia; Shen, Yi; Jin, Ming

2016-12-01

A new technique is proposed to reduce the computational complexity of the multiple signal classification (MUSIC) algorithm for direction-of-arrival (DOA) estimate using a uniform linear array (ULA). The steering vector of the ULA is reconstructed as the Kronecker product of two other steering vectors, and a new cost function with spatial aliasing at hand is derived. Thanks to the estimation ambiguity of this spatial aliasing, mirror angles mathematically relating to the true DOAs are generated, based on which the full spectral search involved in the MUSIC algorithm is highly compressed into a limited angular sector accordingly. Further complexity analysis and performance studies are conducted by computer simulations, which demonstrate that the proposed estimator requires an extremely reduced computational burden while it shows a similar accuracy to the standard MUSIC.

CAST-10-2/DOA 2 Airfoil Studies Workshop Results

NASA Technical Reports Server (NTRS)

Ray, Edward J. (Compiler); Hill, Acquilla S. (Compiler)

1989-01-01

During the period of September 23 through 27, 1988, the Transonic Aerodynamics Division at the Langely Research Center hosted an International Workshop on CAST-10-2/DOA 2 Airfoil Studies. The CAST-10 studies were the outgrowth of several cooperative study agreements among the NASA, the NAE of Canada, the DLR of West Germany, and the ONERA of France. Both theoretical and experimental CAST-10 airfoil results that were obtained form an extensive series of tests and studies, were reviewed. These results provided an opportunity to make direct comparisons of adaptive wall test section (AWTS) results from the NASA 0.3-meter Transonic Cryogenic Tunnel and ONERA T-2 AWTS facilities with conventional ventilated wall wind tunnel results from the Canadian high Reynolds number two-dimensional test facility. Individual papers presented during the workshop are included.

Signal location using generalized linear constraints

NASA Astrophysics Data System (ADS)

Griffiths, Lloyd J.; Feldman, D. D.

1992-01-01

This report has presented a two-part method for estimating the directions of arrival of uncorrelated narrowband sources when there are arbitrary phase errors and angle independent gain errors. The signal steering vectors are estimated in the first part of the method; in the second part, the arrival directions are estimated. It should be noted that the second part of the method can be tailored to incorporate additional information about the nature of the phase errors. For example, if the phase errors are known to be caused solely by element misplacement, the element locations can be estimated concurrently with the DOA's by trying to match the theoretical steering vectors to the estimated ones. Simulation results suggest that, for general perturbation, the method can resolve closely spaced sources under conditions for which a standard high-resolution DOA method such as MUSIC fails.

Retrieval of free-tropospheric BrO from MAX-DOAS measurements at the high-altitude alpine station of Jungfraujoch

NASA Astrophysics Data System (ADS)

Van Roozendael, Michel; Hendrick, Francois; De Smedt, Isabelle; Fayt, Caroline; Gielen, Clio; Hermans, Christian; Pinardi, Gaia; Tack, Frederik; Theys, Nicolas

2014-05-01

There are currently many open questions about the sources, transport, and photochemical processing that control the abundance of BrO and its precursors in the global troposphere. Recent experimental studies based on various platforms and instrumentations indicate contrasting results reflecting the scarcity of the measurements and the experimental challenge of quantifying the typically low abundance levels of BrO. Modeling studies indicate however that the presence of only 1-2 pptv levels of reactive bromine has important consequences for free tropospheric ozone with indirect climate implications. The MAX-DOAS technique offers high sensitivity for near-surface trace gas measurements and it is well suited to BrO detection. From a high altitude site such as the Jungfraujoch which is located in the Swiss Alps at about 3600 m ASL, the free-troposphere can be sampled under favourable conditions. We report on attempts to quantify the free tropospheric BrO level based on MAXDOAS measurements performed by BIRA-IASB in the period from June 2010 until December 2012. Retrievals are based on the DOAS method followed by vertical profile inversion using an Optimal Estimation scheme. The possible sources of bias that can affect the spectral retrieval of BrO are carefully investigated and various sensitivity tests are performed to assess the stability of the inversion. Results are compared with independent estimates of the mid-latitude tropospheric BrO based on satellite measurements.

An overview of VHF lightning observations by digital interferometry from ISS/JEM-GLIMS

NASA Astrophysics Data System (ADS)

Morimoto, Takeshi; Kikuchi, Hiroshi; Sato, Mitsuteru; Ushio, Tomoo; Yamazaki, Atsushi; Suzuki, Makoto; Ishida, Ryohei; Sakamoto, Yuji; Yoshida, Kazuya; Hobara, Yasuhide; Sano, Takuki; Abe, Takumi; Kawasaki, Zen-Ichiro

2016-08-01

The Global Lightning and sprIte MeasurementS (GLIMS) mission has been conducted at the Exposed Facility of Japanese Experiment Module (JEM-EF) of the International Space Station for more than 30 months. This paper focuses on an electromagnetic (EM) payload of JEM-GLIMS mission, the very high frequency (VHF) broadband digital InTerFerometer (VITF). The JEM-GLIMS mission is designed to conduct comprehensive observations with both EM and optical payloads for lightning activities and related transient luminous events. Its nominal operation continued from November 2012 to December 2014. The extended operation followed for eight months. Through the operation period, the VITF collected more than two million VHF EM waveforms in almost 18,700 datasets. The number of VITF observations synchronized with optical signal is 8049. Active VHF radiations are detected in about 70 % of optical observations without obvious regional or seasonal dependency. Estimations of the EM direction-of-arrival (DOA) are attempted using the broadband digital interferometry. Some results agree with the optical observations, even though DOA estimation is problematic because of a very short antenna baseline and multiple pulses over a short time period, namely burst-type EM waveforms. The world's first lightning observations by means of space-borne VHF interferometry are achieved in this mission. This paper summarizes VITF instruments, the recorded VHF EM signals, and the results of DOA estimations by means of digital interferometry as a preliminary report after termination of the mission.[Figure not available: see fulltext.

Signal and array processing techniques for RFID readers

NASA Astrophysics Data System (ADS)

Wang, Jing; Amin, Moeness; Zhang, Yimin

2006-05-01

Radio Frequency Identification (RFID) has recently attracted much attention in both the technical and business communities. It has found wide applications in, for example, toll collection, supply-chain management, access control, localization tracking, real-time monitoring, and object identification. Situations may arise where the movement directions of the tagged RFID items through a portal is of interest and must be determined. Doppler estimation may prove complicated or impractical to perform by RFID readers. Several alternative approaches, including the use of an array of sensors with arbitrary geometry, can be applied. In this paper, we consider direction-of-arrival (DOA) estimation techniques for application to near-field narrowband RFID problems. Particularly, we examine the use of a pair of RFID antennas to track moving RFID tagged items through a portal. With two antennas, the near-field DOA estimation problem can be simplified to a far-field problem, yielding a simple way for identifying the direction of the tag movement, where only one parameter, the angle, needs to be considered. In this case, tracking of the moving direction of the tag simply amounts to computing the spatial cross-correlation between the data samples received at the two antennas. It is pointed out that the radiation patterns of the reader and tag antennas, particularly their phase characteristics, have a significant effect on the performance of DOA estimation. Indoor experiments are conducted in the Radar Imaging and RFID Labs at Villanova University for validating the proposed technique for target movement direction estimations.

Airborne DoA estimation of gunshot acoustic signals using drones with application to sniper localization systems

NASA Astrophysics Data System (ADS)

Fernandes, Rigel P.; Ramos, António L. L.; Apolinário, José A.

2017-05-01

Shooter localization systems have been subject of a growing attention lately owing to its wide span of possible applications, e.g., civil protection, law enforcement, and support to soldiers in missions where snipers might pose a serious threat. These devices are based on the processing of electromagnetic or acoustic signatures associated with the firing of a gun. This work is concerned with the latter, where the shooter's position can be obtained based on the estimation of the direction-of-arrival (DoA) of the acoustic components of a gunshot signal (muzzle blast and shock wave). A major limitation of current commercially available acoustic sniper localization systems is the impossibility of finding the shooter's position when one of these acoustic signatures is not detected. This is very likely to occur in real-life situations, especially when the microphones are not in the field of view of the shockwave or when the presence of obstacles like buildings can prevent a direct-path to sensors. This work addresses the problem of DoA estimation of the muzzle blast using a planar array of sensors deployed in a drone. Results supported by actual gunshot data from a realistic setup are very promising and pave the way for the development of enhanced sniper localization systems featuring two main advantages over stationary ones: (1) wider surveillance area; and (2) increased likelihood of a direct-path detection of at least one of the gunshot signals, thereby adding robustness and reliability to the system.

Airworthiness Designee Function Codes and Consolidated Directory for DMIR/DAR/ODAR/DAS/DOA and SFAR No. 36

DOT National Transportation Integrated Search

1997-05-01

This advisory circular (AC) contains information and guidance concerning : designee application, authorized functions, and initial and subseqent : certificates of authority for Designated Manufacturing Inspection : Representatives (DMIR), Designated ...

Precise DOA Estimation Using SAGE Algorithm with a Cylindrical Array

NASA Astrophysics Data System (ADS)

Takanashi, Masaki; Nishimura, Toshihiko; Ogawa, Yasutaka; Ohgane, Takeo

A uniform circular array (UCA) is a well-known array configuration which can accomplish estimation of 360° field of view with identical accuracy. However, a UCA cannot estimate coherent signals because we cannot apply the SSP owing to the structure of UCA. Although a variety of studies on UCA in coherent multipath environments have been done, it is impossible to estimate the DOA of coherent signals with different incident polar angles. Then, we have proposed Root-MUSIC algorithm with a cylindrical array. However, the estimation performance is degraded when incident signals arrive with close polar angles. To solve this problem, in the letter, we propose to use SAGE algorithm with a cylindrical array. Here, we adopt a CLA Root-MUSIC for the initial estimation and decompose two-dimensional search to double one-dimensional search to reduce the calculation load. The results show that the proposal achieves high resolution with low complexity.

HF Surface Wave Radar Tests at the Eastern China Sea

NASA Astrophysics Data System (ADS)

Wu, Xiong Bin; Cheng, Feng; Wu, Shi Cai; Yang, Zi Jie; Wen, Biyang; Shi, Zhen Hua; Tian, Jiansheng; Ke, Hengyu; Gao, Huotao

2005-01-01

The HF surface wave radar system OSMAR2000 adopts Frequency Modulated Interrupted Continuous Waveform (FMICW) and its 120m-antenna array is transmitting/receiving co-used. MUSIC and MVM are applied to obtain sea echo's direction of arrival (DOA) when extracting currents information. Verification tests of OSMAR2000 ocean surface dynamics detection against in-situ measurements had been accomplished on Oct. 23~29, 2000. Ship detection test was carried out on Dec.24, 2001. It shows that OSMAR2000 is capable of detecting 1000 tons ships with a wide beam out to 70 km. This paper introduces the radar system and the applied DOA estimation methods in the first, and then presents ship detection results and some sea state measurement results of surface currents and waves. The results indicate the validity of the developed radar system and the effectiveness of the applied signal processing methods.

Novel halogen chemistry in the marine boundary layer

NASA Astrophysics Data System (ADS)

Plane, J. M.; Saiz-Lopez, A.; Shillito, J. A.

2003-12-01

This paper will report the first observations of I2 in the marine boundary layer, made by Differential Optical Absorption (DOAS) spectroscopy during a field campaign at Mace Head (Ireland) in the summer of 2002. Very large I2 concentrations correlating with low tide indicate that the source is emission from macro-algae. Simple scaling suggests that this coastal emission could approach 2 Tg per year, making it a major contribution to the global iodine budget. During the same campaign, DOAS observations were also made of the halogen oxides IO, OIO and BrO. The pulses of IO and BrO that were measured at sunrise are strong evidence for heterogeneous processing on sea-salt aerosol producing high levels of IBr during the night. Simple modelling shows that the observed concentrations of the halogen radicals will play important roles in ozone depletion, the oxidation of dimethyl sulfide, and the formation of new particles in the marine boundary layer.

Computationally Efficient 2D DOA Estimation with Uniform Rectangular Array in Low-Grazing Angle.

PubMed

Shi, Junpeng; Hu, Guoping; Zhang, Xiaofei; Sun, Fenggang; Xiao, Yu

2017-02-26

In this paper, we propose a computationally efficient spatial differencing matrix set (SDMS) method for two-dimensional direction of arrival (2D DOA) estimation with uniform rectangular arrays (URAs) in a low-grazing angle (LGA) condition. By rearranging the auto-correlation and cross-correlation matrices in turn among different subarrays, the SDMS method can estimate the two parameters independently with one-dimensional (1D) subspace-based estimation techniques, where we only perform difference for auto-correlation matrices and the cross-correlation matrices are kept completely. Then, the pair-matching of two parameters is achieved by extracting the diagonal elements of URA. Thus, the proposed method can decrease the computational complexity, suppress the effect of additive noise and also have little information loss. Simulation results show that, in LGA, compared to other methods, the proposed methods can achieve performance improvement in the white or colored noise conditions.

Improved Spatial Differencing Scheme for 2-D DOA Estimation of Coherent Signals with Uniform Rectangular Arrays.

PubMed

Shi, Junpeng; Hu, Guoping; Sun, Fenggang; Zong, Binfeng; Wang, Xin

2017-08-24

This paper proposes an improved spatial differencing (ISD) scheme for two-dimensional direction of arrival (2-D DOA) estimation of coherent signals with uniform rectangular arrays (URAs). We first divide the URA into a number of row rectangular subarrays. Then, by extracting all the data information of each subarray, we only perform difference-operation on the auto-correlations, while the cross-correlations are kept unchanged. Using the reconstructed submatrices, both the forward only ISD (FO-ISD) and forward backward ISD (FB-ISD) methods are developed under the proposed scheme. Compared with the existing spatial smoothing techniques, the proposed scheme can use more data information of the sample covariance matrix and also suppress the effect of additive noise more effectively. Simulation results show that both FO-ISD and FB-ISD can improve the estimation performance largely as compared to the others, in white or colored noise conditions.

Computationally Efficient 2D DOA Estimation with Uniform Rectangular Array in Low-Grazing Angle

PubMed Central

Shi, Junpeng; Hu, Guoping; Zhang, Xiaofei; Sun, Fenggang; Xiao, Yu

2017-01-01

In this paper, we propose a computationally efficient spatial differencing matrix set (SDMS) method for two-dimensional direction of arrival (2D DOA) estimation with uniform rectangular arrays (URAs) in a low-grazing angle (LGA) condition. By rearranging the auto-correlation and cross-correlation matrices in turn among different subarrays, the SDMS method can estimate the two parameters independently with one-dimensional (1D) subspace-based estimation techniques, where we only perform difference for auto-correlation matrices and the cross-correlation matrices are kept completely. Then, the pair-matching of two parameters is achieved by extracting the diagonal elements of URA. Thus, the proposed method can decrease the computational complexity, suppress the effect of additive noise and also have little information loss. Simulation results show that, in LGA, compared to other methods, the proposed methods can achieve performance improvement in the white or colored noise conditions. PMID:28245634

Improved Spatial Differencing Scheme for 2-D DOA Estimation of Coherent Signals with Uniform Rectangular Arrays

PubMed Central

Hu, Guoping; Zong, Binfeng; Wang, Xin

2017-01-01

This paper proposes an improved spatial differencing (ISD) scheme for two-dimensional direction of arrival (2-D DOA) estimation of coherent signals with uniform rectangular arrays (URAs). We first divide the URA into a number of row rectangular subarrays. Then, by extracting all the data information of each subarray, we only perform difference-operation on the auto-correlations, while the cross-correlations are kept unchanged. Using the reconstructed submatrices, both the forward only ISD (FO-ISD) and forward backward ISD (FB-ISD) methods are developed under the proposed scheme. Compared with the existing spatial smoothing techniques, the proposed scheme can use more data information of the sample covariance matrix and also suppress the effect of additive noise more effectively. Simulation results show that both FO-ISD and FB-ISD can improve the estimation performance largely as compared to the others, in white or colored noise conditions. PMID:28837115

Direction of Arrival Estimation with a Novel Single-Port Smart Antenna

NASA Astrophysics Data System (ADS)

Sun, Chen; Karmakar, Nemai C.

2004-12-01

A novel direction of arrival (DOA) estimation technique that uses the conventional multiple-signal classification (MUSIC) algorithm with periodic signals is applied to a single-port smart antenna. Results show that the proposed method gives a high-resolution (1 degree) DOA estimation in an uncorrelated signal environment. The novelty lies in that the MUSIC algorithm is applied to a simplified antenna configuration. Only 1 analogue-to-digital converter (ADC) is used in this antenna, which features low power consumption, low cost, and ease of fabrication. Modifications to the conventional MUSIC algorithm do not bring much additional complexity. The proposed technique is also free from the negative influence by the mutual coupling among antenna elements. Therefore, it offers an economical way to extensively implement smart antennas into the existing wireless mobile communications systems, especially at the power consumption limited mobile terminals such as laptops in wireless networks.

Mobile MAX-DOAS and in situ measurements of NO2 and SO2

NASA Astrophysics Data System (ADS)

Wittrock, Folkard; Peters, Enno; Seyler, André; Mathieu-Üffing, Barbara; Kattner, Lisa; Richter, Andreas; Burrows, John P.

2017-04-01

The project MeSMarT (Measurements of shipping emissions in the marine troposphere) has been established as a cooperation between the University of Bremen and the German Bundesamt für Seeschifffahrt und Hydrographie (Federal Maritime and Hydrographic Agency) to estimate the influence of shipping emissions on the chemistry of the atmospheric boundary layer and to establish a monitoring system for main shipping routes. As part of the project in 2015 a mobile lab has been set up, which includes among other instrumentation for air pollution and meteorological parameters a scientific-grade MAX-DOAS system as well as in situ instruments for nitrogen oxides and sulfur dioxide (trace level). Focusing on NO2 and SO2 we present intercomparison results between the different instruments onboard the mobile lab as well as comparisons to standard instrumentation used at different sites in Northern Germany within the project.

Performance evaluation of radiant cooling system application on a university building in Indonesia

NASA Astrophysics Data System (ADS)

Satrio, Pujo; Sholahudin, S.; Nasruddin

2017-03-01

The paper describes a study developed to estimate the energy savings potential of a radiant cooling system installed in an institutional building in Indonesia. The simulations were carried out using IESVE to evaluate thermal performance and energy consumption The building model was calibrated using the measured data for the installed radiant system. Then this calibrated model was used to simulate the energy consumption and temperature distribution to determine the proportional energy savings and occupant comfort under different systems. The result was radiant cooling which integrated with a Dedicated Outside Air System (DOAS) could make 41,84% energy savings compared to the installed cooling system. The Computational Fluid Dynamics (CFD) simulation showed that a radiant system integrated with DOAS provides superior human comfort than a radiant system integrated with Variable Air Volume (VAV). Percentage People Dissatisfied was kept below 10% using the proposed system.

The TORC1-Regulated CPA Complex Rewires an RNA Processing Network to Drive Autophagy and Metabolic Reprogramming.

PubMed

Tang, Hong-Wen; Hu, Yanhui; Chen, Chiao-Lin; Xia, Baolong; Zirin, Jonathan; Yuan, Min; Asara, John M; Rabinow, Leonard; Perrimon, Norbert

2018-05-01

Nutrient deprivation induces autophagy through inhibiting TORC1 activity. We describe a novel mechanism in Drosophila by which TORC1 regulates RNA processing of Atg transcripts and alters ATG protein levels and activities via the cleavage and polyadenylation (CPA) complex. We show that TORC1 signaling inhibits CDK8 and DOA kinases, which directly phosphorylate CPSF6, a component of the CPA complex. These phosphorylation events regulate CPSF6 localization, RNA binding, and starvation-induced alternative RNA processing of transcripts involved in autophagy, nutrient, and energy metabolism, thereby controlling autophagosome formation and metabolism. Similarly, we find that mammalian CDK8 and CLK2, a DOA ortholog, phosphorylate CPSF6 to regulate autophagy and metabolic changes upon starvation, revealing an evolutionarily conserved mechanism linking TORC1 signaling with RNA processing, autophagy, and metabolism. Copyright © 2018 Elsevier Inc. All rights reserved.

TSaT-MUSIC: a novel algorithm for rapid and accurate ultrasonic 3D localization

NASA Astrophysics Data System (ADS)

Mizutani, Kyohei; Ito, Toshio; Sugimoto, Masanori; Hashizume, Hiromichi

2011-12-01

We describe a fast and accurate indoor localization technique using the multiple signal classification (MUSIC) algorithm. The MUSIC algorithm is known as a high-resolution method for estimating directions of arrival (DOAs) or propagation delays. A critical problem in using the MUSIC algorithm for localization is its computational complexity. Therefore, we devised a novel algorithm called Time Space additional Temporal-MUSIC, which can rapidly and simultaneously identify DOAs and delays of mul-ticarrier ultrasonic waves from transmitters. Computer simulations have proved that the computation time of the proposed algorithm is almost constant in spite of increasing numbers of incoming waves and is faster than that of existing methods based on the MUSIC algorithm. The robustness of the proposed algorithm is discussed through simulations. Experiments in real environments showed that the standard deviation of position estimations in 3D space is less than 10 mm, which is satisfactory for indoor localization.

NO2 DOAS Measurements of Traffic Emissions by Chasing Cars

NASA Astrophysics Data System (ADS)

Zhu, Ying; Lipkowitsch, Ivo; Chan, Ka Lok; Bräu, Melanie; Wenig, Mark

2016-04-01

On this poster we present NO2 measurements using a Cavity-Enhanced DOAS on a measurement bus which we used to chase other vehicles to measure their NO2 emissions. Emissions of nitrogen oxides from on-road vehicles have received highly attention recently due to the increasing trend of ambient NOx level. It is particularly important to identify and quantify the direct emission and secondary formation of NO2 contributed by traffic emissions, in order to study the impact to the local air quality. We sampled on-road emissions in different environments and different driving conditions (e.g. urban, highway, different speeds). We analyse the data set in terms of spatial and temporal variability to search for temporal and spatial patterns. We present mean values sorted for different vehicle types, distance to the target car and travelling speeds to provide an emission data base from this measurement study.

Intercomparison of OH Radical Measurements by Long-Path Absorption and Laser Induced Fluorescence in the Atmosphere Simulation Chamber SAPHIR

NASA Astrophysics Data System (ADS)

Dorn, H.-P.; Brauers, T.; Greif, J.; Häseler, R.; Hofzumahaus, A.; Holland, F.; Rupp, L.

2003-04-01

A striking advantage of the SAPHIR chamber is the availability of two spectroscopic detection instruments for OH radicals: Laser-Induced Fluorescence Spectroscopy (LIF) and Long-Path Differential Optical Laser Absorption Spectroscopy (DOAS). Both instruments have already been compared in 1994 during the field measurement campaign POPCORN. They agreed well with a correlation coefficient of r=0.90 and a weighted linear fit with a slope of 1.09 +- 0.12. However, OH measurements in the simulation chamber differ significantly from measurements in ambient air. While DOAS measures OH as an integral value along the central longitudinal axis of SAPHIR, LIF samples the air locally and close (2 cm) to the floor of the chamber. Thus, the LIF measurements might be possibly affected by local concentration gradients caused by insufficient mixing of the chamber air or by deposition to the wall. On the other hand, if turbulent mixing of the chamber air is weak and high concentrations of ozone are used in experiments, the DOAS instrument might be subject to artificial formation of OH radicals in the air volume which is illuminated by the detection laser. This interference results from laser induced photolysis of ozone and the subsequent reaction of water vapor with the excited oxygen atoms formed. Thus it is of decisive importance to compare OH measurements from both instruments in order to investigate potential disturbing effects due to the specific sampling properties of both instruments within SAPHIR. We report on OH measurements accomplished simultaneously with both instruments using different trace gas compositions and experimental conditions.

Genome-wide association analysis on five isolated populations identifies variants of the HLA-DOA gene associated with white wine liking

PubMed Central

Pirastu, Nicola; Kooyman, Maarten; Traglia, Michela; Robino, Antonietta; Willems, Sara M; Pistis, Giorgio; Amin, Najaf; Sala, Cinzia; Karssen, Lennart C; van Duijn, Cornelia M; Toniolo, Daniela; Gasparini, Paolo

2015-01-01

Wine is the most popular alcoholic beverage around the world and because of its importance in society has been widely studied. Understanding what drives its flavor has been a quest for decades but much is still unknown and will be determined at least in part by individual taste preferences. Recently studies in the genetics of taste have uncovered the role of different genes in the determination of food preferences giving new insight on its physiology. In this context we have performed a genome-wide association study on red and white wine liking using three isolated populations collected in Italy, and replicated our results on two additional populations coming from the Netherland and Central Asia for a total of 3885 samples. We have found a significant association (P=2.1 × 10−8) between white wine liking and rs9276975:C>T a polymorphism in the HLA-DOA gene encoding a non-canonical MHC II molecule, which regulates other MHC II molecules. The same association was also found with red wine liking (P=8.3 × 10−6). Sex-separated analysis have also revealed that the effect of HLA-DOA is twice as large in women as compared to men suggesting an interaction between this polymorphism and gender. Our results are one of the first examples of genome-wide association between liking of a commonly consumed food and gene variants. Moreover, our results suggest a role of the MHC system in the determination of food preferences opening new insight in this field in general. PMID:25758996

Monitoring the Depth of Anesthesia Using a New Adaptive Neurofuzzy System.

PubMed

Shalbaf, Ahmad; Saffar, Mohsen; Sleigh, Jamie W; Shalbaf, Reza

2018-05-01

Accurate and noninvasive monitoring of the depth of anesthesia (DoA) is highly desirable. Since the anesthetic drugs act mainly on the central nervous system, the analysis of brain activity using electroencephalogram (EEG) is very useful. This paper proposes a novel automated method for assessing the DoA using EEG. First, 11 features including spectral, fractal, and entropy are extracted from EEG signal and then, by applying an algorithm according to exhaustive search of all subsets of features, a combination of the best features (Beta-index, sample entropy, shannon permutation entropy, and detrended fluctuation analysis) is selected. Accordingly, we feed these extracted features to a new neurofuzzy classification algorithm, adaptive neurofuzzy inference system with linguistic hedges (ANFIS-LH). This structure can successfully model systems with nonlinear relationships between input and output, and also classify overlapped classes accurately. ANFIS-LH, which is based on modified classical fuzzy rules, reduces the effects of the insignificant features in input space, which causes overlapping and modifies the output layer structure. The presented method classifies EEG data into awake, light, general, and deep states during anesthesia with sevoflurane in 17 patients. Its accuracy is 92% compared to a commercial monitoring system (response entropy index) successfully. Moreover, this method reaches the classification accuracy of 93% to categorize EEG signal to awake and general anesthesia states by another database of propofol and volatile anesthesia in 50 patients. To sum up, this method is potentially applicable to a new real-time monitoring system to help the anesthesiologist with continuous assessment of DoA quickly and accurately.

Catalytic Activity of the Anaerobic Tyrosine Lyase Required for Thiamine Biosynthesis in Escherichia coli*

PubMed Central

Challand, Martin R.; Martins, Filipa T.; Roach, Peter L.

2010-01-01

Thiazole synthase in Escherichia coli is an αβ heterodimer of ThiG and ThiH. ThiH is a tyrosine lyase that cleaves the Cα–Cβ bond of tyrosine, generating p-cresol as a by-product, to form dehydroglycine. This reactive intermediate acts as one of three substrates for the thiazole cyclization reaction catalyzed by ThiG. ThiH is a radical S-adenosylmethionine (AdoMet) enzyme that utilizes a [4Fe-4S]+ cluster to reductively cleave AdoMet, forming methionine and a 5′-deoxyadenosyl radical. Analysis of the time-dependent formation of the reaction products 5′-deoxyadenosine (DOA) and p-cresol has demonstrated catalytic behavior of the tyrosine lyase. The kinetics of product formation showed a pre-steady state burst phase, and the involvement of DOA in product inhibition was identified by the addition of 5′-methylthioadenosine/S-adenosylhomocysteine nucleosidase to activity assays. This hydrolyzed the DOA and changed the rate-determining step but, in addition, substantially increased the uncoupled turnover of AdoMet. Addition of glyoxylate and ammonium inhibited the tyrosine cleavage reaction, but the reductive cleavage of AdoMet continued in an uncoupled manner. Tyrosine analogues were incubated with ThiGH, which showed a strong preference for phenolic substrates. 4-Hydroxyphenylpropionic acid analogues allowed uncoupled AdoMet cleavage but did not result in further reaction (Cα–Cβ bond cleavage). The results of the substrate analogue studies and the product inhibition can be explained by a mechanistic hypothesis involving two reaction pathways, a product-forming pathway and a futile cycle. PMID:19923213

Intercomparison of four different in-situ techniques for ambient formaldehyde measurements in urban air

NASA Astrophysics Data System (ADS)

Hak, C.; Pundt, I.; Trick, S.; Kern, C.; Platt, U.; Dommen, J.; Ordóñez, C.; Prévôt, A. S. H.; Junkermann, W.; Astorga-Lloréns, C.; Larsen, B. R.; Mellqvist, J.; Strandberg, A.; Yu, Y.; Galle, B.; Kleffmann, J.; Lörzer, J. C.; Braathen, G. O.; Volkamer, R.

2005-11-01

Results from an intercomparison of several currently used in-situ techniques for the measurement of atmospheric formaldehyde (CH2O) are presented. The measurements were carried out at Bresso, an urban site in the periphery of Milan (Italy) as part of the FORMAT-I field campaign. Eight instruments were employed by six independent research groups using four different techniques: Differential Optical Absorption Spectroscopy (DOAS), Fourier Transform Infra Red (FTIR) interferometry, the fluorimetric Hantzsch reaction technique (five instruments) and a chromatographic technique employing C18-DNPH-cartridges (2,4-dinitrophenylhydrazine). White type multi-reflection systems were employed for the optical techniques in order to avoid spatial CH2O gradients and ensure the sampling of nearly the same air mass by all instruments. Between 23 and 31 July 2002, up to 13 ppbv of CH2O were observed. The concentrations lay well above the detection limits of all instruments. The formaldehyde concentrations determined with DOAS, FTIR and the Hantzsch instruments were found to agree within ±11%, with the exception of one Hantzsch instrument, which gave systematically higher values. The two hour integrated samples by DNPH yielded up to 25% lower concentrations than the data of the continuously measuring instruments averaged over the same time period. The consistency between the DOAS and the Hantzsch method was better than during previous intercomparisons in ambient air with slopes of the regression line not significantly differing from one. The differences between the individual Hantzsch instruments could be attributed in part to the calibration standards used. Possible systematic errors of the methods are discussed.

Intercomparison of four different in-situ techniques for ambient formaldehyde measurements in urban air

NASA Astrophysics Data System (ADS)

Hak, C.; Pundt, I.; Kern, C.; Platt, U.; Dommen, J.; Ordóñez, C.; Prévôt, A. S. H.; Junkermann, W.; Astorga-Lloréns, C.; Larsen, B. R.; Mellqvist, J.; Strandberg, A.; Yu, Y.; Galle, B.; Kleffmann, J.; Lörzer, J. C.; Braathen, G. O.; Volkamer, R.

2005-05-01

Results from an intercomparison of several currently used in-situ techniques for the measurement of atmospheric formaldehyde (CH2O) are presented. The measurements were carried out at Bresso, an urban site in the periphery of Milan (Italy) as part of the FORMAT-I field campaign. Eight instruments were employed by six independent research groups using four different techniques: Differential Optical Absorption Spectroscopy (DOAS), Fourier Transform Infra Red (FTIR) interferometry, the fluorimetric Hantzsch reaction technique (five instruments) and a chromatographic technique employing C18-DNPH-cartridges (2,4-dinitrophenylhydrazine). White type multi-reflection systems were employed for the optical techniques in order to avoid spatial CH2O gradients and ensure the sampling of nearly the same air mass by all instruments. Between 23 and 31 July 2002, up to 13 ppbv of CH2O were observed. The concentrations lay well above the detection limits of all instruments. The formaldehyde concentrations determined with DOAS, FTIR and the Hantzsch instruments were found to agree within ±11%, with the exception of one Hantzsch instrument, which gave systematically higher values. The two hour integrated samples by DNPH yielded up to 25% lower concentrations than the data of the continuously measuring instruments averaged over the same time period. The consistency between the DOAS and the Hantzsch method was better than during previous intercomparisons in ambient air with slopes of the regression line not significantly differing from one. The differences between the individual Hantzsch instruments could be attributed in part to the calibration standards used. Possible systematic errors of the methods are discussed.

Remote measurement of high preeruptive water vapor emissions at Sabancaya volcano by passive differential optical absorption spectroscopy

NASA Astrophysics Data System (ADS)

Kern, Christoph; Masias, Pablo; Apaza, Fredy; Reath, Kevin A.; Platt, Ulrich

2017-05-01

Water (H2O) is by far the most abundant volcanic volatile species and plays a predominant role in driving volcanic eruptions. However, numerous difficulties associated with making accurate measurements of water vapor in volcanic plumes have limited their use as a diagnostic tool. Here we present the first detection of water vapor in a volcanic plume using passive visible-light differential optical absorption spectroscopy (DOAS). Ultraviolet and visible-light DOAS measurements were made on 21 May 2016 at Sabancaya Volcano, Peru. We find that Sabancaya's plume contained an exceptionally high relative water vapor abundance 6 months prior to its November 2016 eruption. Our measurements yielded average sulfur dioxide (SO2) emission rates of 800-900 t/d, H2O emission rates of around 250,000 t/d, and an H2O/SO2 molecular ratio of 1000 which is about an order of magnitude larger than typically found in high-temperature volcanic gases. We attribute the high water vapor emissions to a boiling-off of Sabancaya's hydrothermal system caused by intrusion of magma to shallow depths. This hypothesis is supported by a significant increase in the thermal output of the volcanic edifice detected in infrared satellite imagery leading up to and after our measurements. Though the measurement conditions encountered at Sabancaya were very favorable for our experiment, we show that visible-light DOAS systems could be used to measure water vapor emissions at numerous other high-elevation volcanoes. Such measurements would provide observatories with additional information particularly useful for forecasting eruptions at volcanoes harboring significant hydrothermal systems.

Fungal Colonization and Biodeterioration of Plasticized Polyvinyl Chloride

PubMed Central

Webb, Jeremy S.; Nixon, Marianne; Eastwood, Ian M.; Greenhalgh, Malcolm; Robson, Geoffrey D.; Handley, Pauline S.

2000-01-01

Significant substratum damage can occur when plasticized PVC (pPVC) is colonized by microorganisms. We investigated microbial colonization of pPVC in an in situ, longitudinal study. Pieces of pPVC containing the plasticizers dioctyl phthalate and dioctyl adipate (DOA) were exposed to the atmosphere for up to 2 years. Fungal and bacterial populations were quantified, and colonizing fungi were identified by rRNA gene sequencing and morphological characteristics. Aureobasidium pullulans was the principal colonizing fungus, establishing itself on the pPVC between 25 and 40 weeks of exposure. A group of yeasts and yeast-like fungi, including Rhodotorula aurantiaca and Kluyveromyces spp., established themselves on the pPVC much later (after 80 weeks of exposure). Numerically, these organisms dominated A. pullulans after 95 weeks, with a mean viable count ± standard error of 1,000 ± 200 yeast CFU cm−2, compared to 390 ± 50 A. pullulans CFU cm−2. No bacterial colonization was observed. We also used in vitro tests to characterize the deteriogenic properties of fungi isolated from the pPVC. All strains of A. pullulans tested could grow with the intact pPVC formulation as the sole source of carbon, degrade the plasticizer DOA, produce extracellular esterase, and cause weight loss of the substratum during growth in vitro. In contrast, several yeast isolates could not grow on pPVC or degrade DOA. These results suggest that microbial succession may occur during the colonization of pPVC and that A. pullulans is critical to the establishment of a microbial community on pPVC. PMID:10919769

Development of 2-D-MAX-DOAS and retrievals of trace gases and aerosols optical properties

NASA Astrophysics Data System (ADS)

Ortega, Ivan

Air pollution is a major problem worldwide that adversely a_ects human health, impacts ecosystems and climate. In the atmosphere, there are hundreds of important compounds participating in complex atmospheric reactions linked to air quality and climate. Aerosols are relevant because they modify the radiation balance, a_ect clouds, and thus Earth albedo. The amount of aerosol is often characterized by the vertical integral through the entire height of the atmosphere of the logarithm fraction of incident light that is extinguished called Aerosol Optical Depth (AOD). The AOD at 550 nm (AOD550) over land is 0.19 (multi annual global mean), and that over oceans is 0.13. About 43 % of the Earth surface shows AOD550 smaller than 0.1. There is a need for measurement techniques that are optimized to measure aerosol optical properties under low AOD conditions, sample spatial scales that resemble satellite ground-pixels and atmospheric models, and help integrate remote sensing and in-situ observations to obtain optical closure on the effects of aerosols and trace gases in our changing environment. In this work, I present the recent development of the University of Colorado two dimensional (2-D) Multi-AXis Differential Optical Absorption Spectroscopy (2-D-MAX-DOAS) instrument to measure the azimuth and altitude distribution of trace gases and aerosol optical properties simultaneously with a single instrument. The instrument measures solar scattered light from any direction in the sky, including direct sun light in the hyperspectral domain. In Chapter 2, I describe the capabilities of 2-D measurements in the context of retrievals of azimuth distributions of nitrogen dioxide (NO2), formaldehyde (HCHO), and glyoxal (CHOCHO), which are precursors for tropospheric O3 and aerosols. The measurements were carried out during the Multi-Axis DOAS Comparison campaign for Aerosols and Trace gases (MAD-CAT) campaign in Mainz, Germany and show the ability to bridge spatial scales to satellites and atmospheric models. Chapter 3 presents an innovative retrieval approach to measure AOD430 and the aerosol phase function parameter, g, without the need for absolute radiance calibration; the retrieval is based on solar azimuth distributions of the Raman Scattering Probability (RSP), the near-absolute Rotational Raman Scattering (RRS) intensity, during the Department of Energy Two Column Aerosol Project (TCAP) at Cape Cod, MA. Furthermore, the TCAP field campaign provides a unique dataset to evaluate innovative retrieval algorithms and perform radiation closure studies. In Chapters 4 I describe the effect of persistent elevated aerosol layers on the apparent absorption of the collision induced absorption of oxygen (O2-O2, or O4) as seen by the ground based 2-D-MAX-DOAS. Chapter 5 discusses the effect of chemical composition of aerosols for optical closure of aerosol extinction as characterized by ground based (2-D-MAX-DOAS) and airborne remote sensing instruments (HSRL-2) and in-situ observations of aerosol optical properties calculated from size distributions measured aboard the DoE G-1 aircraft. Chapter 5 also includes a discussion on the effects of dry, moist, and size-corrections that need to be applied to the in-situ observations in order to infer extinction in the atmosphere. In the final Chapter 6, I present a comprehensive analysis of CHOCHO, HCHO, and NO2 column measurements obtained in multiple field deployments of MAX-DOAS under different NOx (NO + NO2) conditions and VOC precursors. In particular, I assess the magnitude of the ratio of CHOCHO to HCHO (RGF), which has been proposed as a metric to distinguish biogenic and/or anthropogenic VOC (BVOC/AVOC) influences, and show with box-modeling that the concentration of NO2 and dictates the value of RGF . I proposed a new metric of RGF based on box-modeling and field measurements to distinguish AVOC/BVOC influences and split in BVOCs.

Development and application of a low-cost, portable DOAS system for stratospheric composition monitoring over the Argentinean Patagonia and Antarctic stations.

NASA Astrophysics Data System (ADS)

Raponi, Marcelo; Jiménez, Rodrigo; Ristori, Pablo; Wolfram, Elian; Tocho, Jorge; Quel, Eduardo

2010-05-01

A significant fraction of the Argentinean population is seasonally exposed to elevated UV radiation, particularly during severe stratospheric ozone destruction episodes in Antarctica. In order to provide early alert, global monitoring and to improve our understanding of these phenomena, various Argentinean and international organizations maintain stratospheric composition remote sensing sites from the southern tip of Argentina (Patagonia) to Antarctica. The understating of the ozone destruction dynamics will be significantly improved if more sites were available. For instance, the Laser and Applications Research Center, CEILAP (CITEFA-CONICET, Argentina) carries out systematic measurements of stratospheric ozone and tropospheric water vapor profiles at Rio Gallego (51° 36' S, 69° 19' W, 15 m asl) by means of LIDAR systems. Besides the active systems, the site possesses different passive instruments (GUV-541, UV-B and UV-A radiometers, SAOZ spectrometer, CIMEL sunphotometer) all of them working in synergy. The goal of this work is to present the design and development of a new compact atmospheric remote sensing system, able to determine the vertical column concentration in column (VCD) of multiple trace gases. We have developed a low-cost, portable passive DOAS system, ERO-DOAS, wich circumvents the cost limitations associated with new fixed monitoring sites. It is composed of commercial spectrophotometer (HR4000, Ocean Optics), a 400-μm core, 6-m long optic fiber, and a home-made automatic external shutter. We have developed a LabVIEW® based software for spectrometer/shutter control and data acquisition, and a MATLAB® based software for spectral data reduction. In the work we highlight the main characteristics of the system's components and we describe the visual interface implemented to controls the operation of the whole system, and the calculation algorithms to process the measured zenithal spectra, postulating the strategies implemented to solve the challenge. Also, we present measurements carry out at the Marambio Antarctic Base (64° 14' S; 56° 37' W, 197 m asl) during the months of January - February of 2008, using the ERO-DOAS. The NO2 and O3 VCD are derived from solar spectra acquired during the twilights (zenithal angles between 87° - 92° ), using the DOAS (Differential Optical Absorption Spectroscopy) technique. The biggest contribution to these spectra comes from the stratosphere, atmosphere layer that we want to study. The analysis is carried out by solving the Beer-Lambert-Bouger (BLB) law for all the atmospheric absorbers and a quasi-continuous wavelength range. The algorithm minimizes the fitting residuals to the BLB law, having as unknown the slant column density of the species to determine. The effects of Rayleigh and Mie scattering, fluorescence and most of the Raman scattering are accounted for and subtracted out using a high-pass polynomial filter. We compare the data acquired by our DOAS system with co-located measurements performed with EVA, a visible absorption spectrometer operated by the Instituto Nacional de Técnica Aeroespacial (INTA), Spain. Additionally, a comparative study is presented among the ground-based signals and those obtained by the instrument OMI (AURA satellite). The bigger mistake sources associated with the comparison between AURA satellite observations and those carried out from earth are: a) NOx daily cycle, b) NO2 natural variability, and c) NO2 tropospheric sensibility. In the case of Marambio, it hasn't relevance since it is non polluted places and the tropospheric NO2 level is very low. We observe that the NO2 has a strong photochemical variability during the day. This variability is associated with the solar cycle, the NOx vertical distribution, the temperature in the high layers of the atmosphere and sometimes (in high latitudes) of other active species.

Measurement of atmospheric ammonia at a dairy using differential optical absorption spectroscopy in the mid-ultraviolet

NASA Astrophysics Data System (ADS)

Mount, George H.; Rumburg, Brian; Havig, Jeff; Lamb, Brian; Westberg, Hal; Yonge, David; Johnson, Kristen; Kincaid, Ronald

Ammonia is the most abundant basic gas in the atmosphere, and after N 2 and N 2O is the most abundant nitrogen-containing specie (Seinfeld and Pandis, 1998. Atmospheric Chemistry and Physics: from air pollution to climate changes. Wiley, New York). Typical concentrations of ammonia in the boundary layer range from <1 part per billion by volume (ppbv) in the free continental troposphere to parts per million (ppmv) levels over animal waste lagoons and near animal stalls. Agricultural activities are the dominant global source of ammonia emissions and a major environmental concern. In the US, ≈85% of ammonia emissions come from livestock operations (EPA Trends, 1998. www.epa.gov/ttn/chief/trends98/chapter2.pdf). Dairy farms constitute a large fraction of the livestock inventory. Current estimates of ammonia emissions to the atmosphere are characterized by a high degree of uncertainty, and so it is very important to obtain better estimates of ammonia emissions. We are working at the Washington State University research dairy to quantify ammonia emissions and investigate the effects of various mitigation strategies on those emissions. We describe here a new instrument utilizing the differential optical absorption spectroscopy (DOAS) technique to measure ammonia in the mid-ultraviolet with a detectability limit of about 1 ppb. DOAS avoids many of the problems that have thwarted past ammonia concentration measurements. Initial results show concentrations in the barn/concrete yard areas in the tens of parts per million range, over the slurry lagoons of hundreds of parts per billion to low parts per million, and low parts per million levels after initial slurry applications onto pastureland. Future papers will report on emission fluxes from the various parts of the dairy and the results of mitigation strategies; we show here initial data results. For a recent review of ammonia volatilization from dairy farms, see Bussink and Oenema (Nutrient Cycling in Agroecosystems 51(1998) 19).

MEASUREMENT OF LOW LEVEL AIR TOXICS WITH MODIFIED UV DOAS

EPA Science Inventory

To further understand near source impacts, EPA is working to develop open-path optical techniques for spatiotemporal-resolved measurement of air pollutants. Of particular interest is near real time quantification of mobile-source generated CO, Nox and hydrocarbons measured in cl...

Axle Lubricant Efficiency

DTIC Science & Technology

2014-05-09

state or reflect those of the United States Government or the DoA, and shall not be used for advertising or product endorsement purposes...Engine Control Module FMTV Family of Medium Tactical Vehicles GO Gear Oil GPS Global Positioning System GVW Gross Vehicle Weight HDO Heavy Duty Oil

Remote measurement of high preeruptive water vapor emissions at Sabancaya volcano by passive differential optical absorption spectroscopy

USGS Publications Warehouse

Kern, Christoph; Masias, Pablo; Apaza, Fredy; Reath, Kevin; Platt, Ulrich

2017-01-01

Water (H2O) is by far the most abundant volcanic volatile species and plays a predominant role in driving volcanic eruptions. However, numerous difficulties associated with making accurate measurements of water vapor in volcanic plumes have limited their use as a diagnostic tool. Here we present the first detection of water vapor in a volcanic plume using passive visible-light differential optical absorption spectroscopy (DOAS). Ultraviolet and visible-light DOAS measurements were made on 21 May 2016 at Sabancaya Volcano, Peru. We find that Sabancaya's plume contained an exceptionally high relative water vapor abundance 6 months prior to its November 2016 eruption. Our measurements yielded average sulfur dioxide (SO2) emission rates of 800–900 t/d, H2O emission rates of around 250,000 t/d, and an H2O/SO2 molecular ratio of 1000 which is about an order of magnitude larger than typically found in high-temperature volcanic gases. We attribute the high water vapor emissions to a boiling-off of Sabancaya's hydrothermal system caused by intrusion of magma to shallow depths. This hypothesis is supported by a significant increase in the thermal output of the volcanic edifice detected in infrared satellite imagery leading up to and after our measurements. Though the measurement conditions encountered at Sabancaya were very favorable for our experiment, we show that visible-light DOAS systems could be used to measure water vapor emissions at numerous other high-elevation volcanoes. Such measurements would provide observatories with additional information particularly useful for forecasting eruptions at volcanoes harboring significant hydrothermal systems.

The influence of polarization on box air mass factors for UV/vis nadir satellite observations

NASA Astrophysics Data System (ADS)

Hilboll, Andreas; Richter, Andreas; Rozanov, Vladimir V.; Burrows, John P.

2015-04-01

Tropospheric abundances of pollutant trace gases like, e.g., NO2, are often derived by applying the differential optical absorption spectroscopy (DOAS) method to space-borne measurements of back-scattered and reflected solar radiation. The resulting quantity, the slant column density (SCD), subsequently has to be converted to more easily interpretable vertical column densities by means of the so-called box air mass factor (BAMF). The BAMF describes the ratio of SCD and VCD within one atmospheric layer and is calculated by a radiative transfer model. Current operational and scientific data products of satellite-derived trace gas VCDs do not include the effect of polarization in their radiative transfer models. However, the various scattering processes in the atmosphere do lead to a distinctive polarization pattern of the observed Earthshine spectra. This study investigates the influence of these polarization patterns on box air mass factors for satellite nadir DOAS measurements of NO2 in the UV/vis wavelength region. NO2 BAMFs have been simulated for a multitude of viewing geometries, surface albedos, and surface altitudes, using the radiative transfer model SCIATRAN. The results show a potentially large influence of polarization on the BAMF, which can reach 10% and more close to the surface. A simple correction for this effect seems not to be feasible, as it strongly depends on the specific measurement scenario and can lead to both high and low biases of the resulting NO2 VCD. We therefore conclude that all data products of NO2 VCDs derived from space-borne DOAS measurements should include polarization effects in their radiative transfer model calculations, or at least include the errors introduced by using linear models in their uncertainty estimates.

A new method research of monitoring low concentration NO and SO2 mixed gas

NASA Astrophysics Data System (ADS)

Bo, Peng; Gao, Chao; Guo, Yongcai; Chen, Fang

2018-01-01

In order to reduce the pollution of the environment, China has implemented a new ultra-low emission control regulations for polluting gas, requiring new coal-fired power plant emissions SO2 less than 30ppm, NO less than 75ppm, NO2 less than 50ppm, Monitoring low concentration of NO and SO2 mixed gases , DOAS technology facing new challenges, SO2 absorb significantly weaken at the original absorption peak, what more the SNR is very low, it is difficult to extract the characteristic signal, and thus cannot obtain its concentration. So it cannot separate the signal of NO from the mixed gas at the wavelength of 200 230nm through the law of spectral superposition, it cannot calculate the concentration of NO. The classical DOAS technology cannot meet the needs of monitoring. In this paper, we found another absorption spectrum segment of SO2, the SNR is 10 times higher than before, Will not be affected by NO, can calculate the concentration of SO2 accurately, A new method of segmentation and demagnetization separation technology of spectral signals is proposed, which achieves the monitoring the low concentration mixed gas accurately. This function cannot be achieved by the classical DOAS. Detection limit of this method is 0.1ppm per meter which is higher than before, The relative error below 5% when the concentration between 0 5ppm, the concentration of NO between 6 75ppm and SO2 between 6 30ppm the relative error below 1.5%, it has made a great breakthrough In the low concentration of NO and SO2 monitoring. It has great scientific significance and reference value for the development of coal-fired power plant emission control, atmospheric environmental monitoring and high-precision on-line instrumentation.

Trace gas retrieval for limb DOAS under changing atmospheric conditions: The X-gas scaling method vs optimal estimation

NASA Astrophysics Data System (ADS)

Hueneke, Tilman; Grossmann, Katja; Knecht, Matthias; Raecke, Rasmus; Stutz, Jochen; Werner, Bodo; Pfeilsticker, Klaus

2016-04-01

Changing atmospheric conditions during DOAS measurements from fast moving aircraft platforms pose a challenge for trace gas retrievals. Traditional inversion techniques to retrieve trace gas concentrations from limb scattered UV/vis spectroscopy, like optimal estimation, require a-priori information on Mie extinction (e.g., aerosol concentration and cloud cover) and albedo, which determine the atmospheric radiative transfer. In contrast to satellite applications, cloud filters can not be applied because they would strongly reduce the usable amount of expensively gathered measurement data. In contrast to ground-based MAX-DOAS applications, an aerosol retrieval based on O4 is not able to constrain the radiative transfer in air-borne applications due to the rapidly decreasing amount of O4 with altitude. Furthermore, the assumption of a constant cloud cover is not valid for fast moving aircrafts, thus requiring 2D or even 3D treatment of the radiative transfer. Therefore, traditional techniques are not applicable for most of the data gathered by fast moving aircraft platforms. In order to circumvent these limitations, we have been developing the so-called X-gas scaling method. By utilising a proxy gas X (e.g. O3, O4, …), whose concentration is either a priori known or simultaneously in-situ measured as well as remotely measured, an effective absorption length for the target gas is inferred. In this presentation, we discuss the strengths and weaknesses of the novel approach along with some sample cases. A particular strength of the X-gas scaling method is its insensitivity towards the aerosol abundance and cloud cover as well as wavelength dependent effects, whereas its sensitivity towards the profiles of both gases requires a priori information on their shapes.

Radicals and Aerosols in the Troposphere and Lower Stratosphere

NASA Astrophysics Data System (ADS)

Volkamer, Rainer; Koenig, Theodore; Dix, Barbara

2016-06-01

The remote tropical free troposphere (FT) is one of the most relevant atmospheric environments on Earth. About 75% of the global tropospheric O3 and CH4 loss occurs at tropical latitudes. Tropospheric bromine and iodine catalytically destroy tropospheric O3, oxidize atmospheric mercury, and modify oxidative capacity, and aerosols. Oxygenated VOCs (OVOC) modify HOx (= OH + HO2), NOx (= NO + NO2), tropospheric O3, aerosols, and are a sink for BrOx (= Br + BrO). Until recently, atmospheric models were untested for lack of vertically resolved measurements of BrO and IO radicals in the tropical troposphere. BrO and IO are highly reactive trace gases. Even very low concentrations (parts per trillion; 1 pptv = 10-12 volume mixing ratio) can significantly modify the lifetime of climate active gases, and determine (bromine) the rate limiting step of mercury oxidation in air (that is washed out, and subsequently bio-accumulates in fish). Analytical challenges arise when these radicals modify in sampling lines. Sensitive yet robust, portable, and inherently calibrated measurements directly in the open atmosphere have recently been demonstrated by means of limb-measurements of scattered solar photons by the University of Colorado Airborne Multi-AXis DOAS instrument (CU AMAX-DOAS) from research aircraft. The CU AMAX-DOAS instrument is optimized to (1) locate BrO, IO and glyoxal (a short lived OVOC) in the troposphere, (2) decouple stratospheric absorbers, (3) maximize sensitivity at instrument altitude, (4) facilitate altitude control and (5) enable observations over a wide range of solar zenith angles. Further, (6) the filling-in of Fraunhofer lines (Ring-effect) by Raman Scattering offers interesting opportunities for radiative closure studies to assess the effects of aerosols on Climate.

Monitoring shipping emissions with MAX-DOAS measurements of reactive trace gases

NASA Astrophysics Data System (ADS)

Wittrock, Folkard; Peters, Enno; Seyler, André; Kattner, Lisa; Mathieu-Üffing, Barbara; Burrows, John P.; Chirkov, Maksym; Meier, Andreas C.; Richter, Andreas; Schönhardt, Anja; Schmolke, Stefan; Theobald, Norbert

2014-05-01

Air pollution from ships contributes to overall air quality problems and it has direct health effects on the population in particular in coastal regions, and in harbor cities. In order to reduce the emissions the International Maritime Organisation (IMO) have tightened the regulations for air pollution. E.g. Sulfur Emission Control Areas (SECA) have been introduced where the sulfur content of marine fuel is limited. However, up to now there is no regular monitoring system available to verify that ships are complying with the new regulations. Furthermore measurements of reactive trace gases in marine environments are in general sparse. The project MeSMarT (Measurements of shipping emissions in the marine troposphere, www.mesmart.de) has been established as a cooperation between the University of Bremen and the German Bundesamt für Seeschifffahrt und Hydrographie (Federal Maritime and Hydrographic Agency) with support of the Helmholtz Research Centre Geesthacht to estimate the influence of ship emissions on the chemistry of the atmospheric boundary layer and to establish a monitoring system for main shipping routes. Here we present MAX-DOAS observations of NO2 and SO2 carried out during ship campaigns in the North and Baltic Sea and from two permanent sites close to the Elbe river (Wedel, Germany) and on the island Neuwerk close to the mouths of Elbe and Weser river. Mixing ratios of both trace gases have been retrieved using different approaches (pure geometric and taking into account the radiative transfer) and compared to in situ and air borne observations (see Kattner et al., Monitoring shipping emissions with in-situ measurements of trace gases, and Meier et al., Airborne measurements of NO2 shipping emissions using imaging DOAS) observations. Furthermore simple approaches have been used to calculate emission factors of NOx and SO2 for single ships.

Total Ozone from the Ozone Monitoring System (OMI) using TOMS and DOAS Methods

NASA Technical Reports Server (NTRS)

Veefkind, J. P.; Bhartia, P. K.; Gleason, J.; deHaan, J. F.; Wellemeyer, C.; Levelt, P. F.

2003-01-01

The Ozone Monitoring Instrument (OMI) is the Dutch-Finnish contribution to NASA's EOS-Aura satellite scheduled for launch in January 2004. OMI is an imaging spectrometer that will measure the back-scattered Solar radiance in the wavelength range of 270 to 500 nm. The instrument provides near global coverage in one day with a spatial resolution of 13x24 square kilometers. OMI is a new instrument, with a heritage from TOMS, SBW, GOME, GOMOS and SCIAMACHY. OMI'S unique capabilities for measuring important trace gases and aerosols with a small footprint and daily global coverage, in conjunction with the other Aura instruments, will make a major contribution to our understanding of stratospheric and tropospheric chemistry and climate change. OMI will provide data continuity with the 23-year ozone record of TOMS. There are three ozone products planned for OMI: total column ozone, ozone profile and tropospheric column ozone. We are developing two different algorithms for total column ozone: one similar to the algorithm currently being used to process the TOMS data, and the other an improved version of the differential optical absorption spectroscopy (DOAS) method, which has been applied to GOME and SCIAMACHY data. The main reasons for starting with two algorithms for total ozone have to do with heritage and past experience; our long-term goal is to combine the two to develop a more accurate and reliable total ozone product for OMI. We will compare the performance of these two algorithms by applying both of them to the GOME data. We will examine where and how the results differ, and use the extensive TOMS-Dobson comparison studies to assess the performance of the DOAS algorithm.

Recent observations of carbon and sulfur gas emissions from Tavurvur, Bagana and Ulawun (Papua New Guinea) with a combination of ground- and air-borne direct and remote sensing techniques

NASA Astrophysics Data System (ADS)

Arellano, Santiago; Galle, Bo; Mulina, Kila; Wallius, Julia; McCormick, Brendan; Salem, Lois; D'aleo, Roberto; Itikarai, Ima; Tirpitz, Lukas; Bobrowski, Nicole; Aiuppa, Alessandro

2017-04-01

Satellite observations reveal that volcanoes from Papua New Guinea contributed with ca. 15{%} of the global emission of volcanic sulfur dioxide (SO2) during the period 2005-2014. Relatively little is known about their carbon dioxide (CO2) outputs and more recent levels and dynamics of degassing activity. During September 2016 we conducted measurements of the CO2/SO2 ratio and the SO2 flux from Tavurvur, Bagana and Ulawun volcanoes using a combination of remote sensing and direct sampling techniques. Tavurvur exhibits low-level passive degassing from a modestly active vent and few other intra-crater fumaroles, which made access possible for direct measurements of the CO2/SO2 ratio with a compact Multi-GAS instrument. A wide-field of view pointing DOAS monitor was deployed for longer term monitoring of the SO2 flux from a distance of about 2 km. Bagana degasses continuously with occasional emissions of ash, and its SO2 flux, plume velocity and height was constrained by simultaneous scanning and dual-beam DOAS measurements. Molar ratios in the plume of Bagana were measured by the compact Multi-GAS aboard a multi-rotor UAV, up to a height of 1.6 km above ground. Ulawun showed continuous passive degassing and measurements with the UAV, up to an altitude of ca. 1.8 km, and mobile-DOAS traverses from a car were used to constrain its gas emission. Here we present an overview of the challenging conditions, measurement strategies and results of this campaign that forms part of the ongoing international effort DECADE aiming to better quantify the global gas emission of carbon- and sulfur containing species from volcanoes.

NEAR ROAD NITRIC OXIDE AND HYDROCARBON MEASUREMENTS WITH DUV-DOAS

EPA Science Inventory

As part of the overall EPA effort to increase understanding of the distribution of air pollutants in near road environments, optical remote sensing techniques developed for area source measurement are being used to assess mobile source emissions and dispersion from roadway segmen...

DOAS-based total column ozone retrieval from Phaethon system

NASA Astrophysics Data System (ADS)

Gkertsi, F.; Bais, A. F.; Kouremeti, N.; Drosoglou, Th; Fountoulakis, I.; Fragkos, K.

2018-05-01

This study introduces the measurement of the total ozone column using Differential Optical Absorption Spectroscopy (DOAS) analysis of direct-sun spectra recorded by the Phaethon system. This methodology is based on the analysis of spectra relative to a reference spectrum that has been recorded by the same instrument. The slant column density of ozone associated with the reference spectrum is derived by Langley extrapolation. Total ozone data derived by Phaethon over two years in Thessaloniki are compared with those of a collocated, well-maintained and calibrated, Brewer spectrophotometer. When the retrieval of total ozone is based on the absorption cross sections of (Paur and Bass, 1984) at 228 K, Phaethon shows an average overestimation of 1.85 ± 1.86%. Taking into account the effect of the day-to-day variability of stratospheric temperature on total ozone derived by both systems, the bias is reduced to 0.94 ± 1.26%. The sensitivity of the total ozone retrieval to changes in temperature is larger for Phaethon than for Brewer.

Degree-of-Freedom Strengthened Cascade Array for DOD-DOA Estimation in MIMO Array Systems.

PubMed

Yao, Bobin; Dong, Zhi; Zhang, Weile; Wang, Wei; Wu, Qisheng

2018-05-14

In spatial spectrum estimation, difference co-array can provide extra degrees-of-freedom (DOFs) for promoting parameter identifiability and parameter estimation accuracy. For the sake of acquiring as more DOFs as possible with a given number of physical sensors, we herein design a novel sensor array geometry named cascade array. This structure is generated by systematically connecting a uniform linear array (ULA) and a non-uniform linear array, and can provide more DOFs than some exist array structures but less than the upper-bound indicated by minimum redundant array (MRA). We further apply this cascade array into multiple input multiple output (MIMO) array systems, and propose a novel joint direction of departure (DOD) and direction of arrival (DOA) estimation algorithm, which is based on a reduced-dimensional weighted subspace fitting technique. The algorithm is angle auto-paired and computationally efficient. Theoretical analysis and numerical simulations prove the advantages and effectiveness of the proposed array structure and the related algorithm.

Positive state observer for the automatic control of the depth of anesthesia-Clinical results.

PubMed

Nogueira, Filipa N; Mendonça, T; Rocha, P

2016-09-13

The depth of anesthesia (DoA) is a crucial feature in general anesthesia. Nowadays the DoA is usually evaluated by the bispectral index (BIS). According to the surgical procedure, different reference levels for the BIS may be clinically required. This can be achieved by the simultaneous administration of an analgesic (e.g. remifentanil) and an hypnotic (eg propofol). As a contribution to the effort of automating the processes of drug delivery in general anesthesia, in this paper, a positive state observer is designed for the implementation of a control scheme proposed for the automatic administration of propofol and of remifentanil, in order to track a desired level for the BIS. It is proved and illustrated by simulations that the controller-observer scheme has a very good performance. This scheme was implemented, tested and evaluated both by means of simulations and for a set of patients during surgical procedures. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Acoustic source localization in mixed field using spherical microphone arrays

NASA Astrophysics Data System (ADS)

Huang, Qinghua; Wang, Tong

2014-12-01

Spherical microphone arrays have been used for source localization in three-dimensional space recently. In this paper, a two-stage algorithm is developed to localize mixed far-field and near-field acoustic sources in free-field environment. In the first stage, an array signal model is constructed in the spherical harmonics domain. The recurrent relation of spherical harmonics is independent of far-field and near-field mode strengths. Therefore, it is used to develop spherical estimating signal parameter via rotational invariance technique (ESPRIT)-like approach to estimate directions of arrival (DOAs) for both far-field and near-field sources. In the second stage, based on the estimated DOAs, simple one-dimensional MUSIC spectrum is exploited to distinguish far-field and near-field sources and estimate the ranges of near-field sources. The proposed algorithm can avoid multidimensional search and parameter pairing. Simulation results demonstrate the good performance for localizing far-field sources, or near-field ones, or mixed field sources.

Single-snapshot DOA estimation by using Compressed Sensing

NASA Astrophysics Data System (ADS)

Fortunati, Stefano; Grasso, Raffaele; Gini, Fulvio; Greco, Maria S.; LePage, Kevin

2014-12-01

This paper deals with the problem of estimating the directions of arrival (DOA) of multiple source signals from a single observation vector of an array data. In particular, four estimation algorithms based on the theory of compressed sensing (CS), i.e., the classical ℓ 1 minimization (or Least Absolute Shrinkage and Selection Operator, LASSO), the fast smooth ℓ 0 minimization, and the Sparse Iterative Covariance-Based Estimator, SPICE and the Iterative Adaptive Approach for Amplitude and Phase Estimation, IAA-APES algorithms, are analyzed, and their statistical properties are investigated and compared with the classical Fourier beamformer (FB) in different simulated scenarios. We show that unlike the classical FB, a CS-based beamformer (CSB) has some desirable properties typical of the adaptive algorithms (e.g., Capon and MUSIC) even in the single snapshot case. Particular attention is devoted to the super-resolution property. Theoretical arguments and simulation analysis provide evidence that a CS-based beamformer can achieve resolution beyond the classical Rayleigh limit. Finally, the theoretical findings are validated by processing a real sonar dataset.

NO2 and HCHO variability in Mexico City from MAX-DOAS measurements

NASA Astrophysics Data System (ADS)

Grutter, M.; Friedrich, M. M.; Rivera, C. I.; Arellano, E. J.; Stremme, W.

2015-12-01

Atmospheric studies in large cities are of great relevance since pollution affects air quality and human health. A network of Multi Axis Differential Optical Absorption Spectrometers (MAX-DOAS) has been established in strategic sites within the Mexico City metropolitan area. Four instruments are now in operation with the aim to study the variability and spatial distribution of key pollutants, providing results of O4, NO2 and HCHO slant column densities (SCD). A numerical code has been written to retrieve gas profiles of NO2 and HCHO using radiative transfer simulations. We present the first results of the variability of these trace gases which will bring new insight in the current knowledge of transport patterns, emissions as well as frequency and origin of extraordinary events. Results of the vertical column densities (VCD) valiability of NO2 and HCHO in Mexico City are presented. These studies are useful to validate current and future satellite observatopns such as OMI, TROPOMI and TEMPO.

High Reynolds number tests of the CAST 10-2/DOA 2 airfoil in the Langley 0.3-meter transonic cryogenic tunnel, phase 1

NASA Technical Reports Server (NTRS)

Dress, D. A.; Mcguire, P. D.; Stanewsky, E.; Ray, E. J.

1983-01-01

A wind tunnel investigation of an advanced technology airfoil, the CAST 10-2/DOA 2, was conducted in the Langley 0.3 meter Transonic Cryogenic Tunnel (0.3 m TCT). This was the first of a series of tests conducted in a cooperative National Aeronautics and Space Administration (NASA) and the Deutsche Forschungs- und Versuchsanstalt fur Luft- und Raumfahrt e. V. (DFVLR) airfoil research program. Test temperature was varied from 280 K to 100 K to pressures from slightly above 1 to 5.8 atmospheres. Mach number was varied from 0.60 to 0.80, and the Reynolds number (based on airfoil chord) was varied from 4 x 10 to the 8th power to 45 x 10 to the 6th power. This report presents the experimental aerodynamic data obtained for the airfoil and includes descriptions of the airfoil model, the 0.3 m TCT, the test instrumentation, and the testing procedures.

Multi-Target Angle Tracking Algorithm for Bistatic MIMO Radar Based on the Elements of the Covariance Matrix

PubMed Central

Zhang, Zhengyan; Zhang, Jianyun; Zhou, Qingsong; Li, Xiaobo

2018-01-01

In this paper, we consider the problem of tracking the direction of arrivals (DOA) and the direction of departure (DOD) of multiple targets for bistatic multiple-input multiple-output (MIMO) radar. A high-precision tracking algorithm for target angle is proposed. First, the linear relationship between the covariance matrix difference and the angle difference of the adjacent moment was obtained through three approximate relations. Then, the proposed algorithm obtained the relationship between the elements in the covariance matrix difference. On this basis, the performance of the algorithm was improved by averaging the covariance matrix element. Finally, the least square method was used to estimate the DOD and DOA. The algorithm realized the automatic correlation of the angle and provided better performance when compared with the adaptive asymmetric joint diagonalization (AAJD) algorithm. The simulation results demonstrated the effectiveness of the proposed algorithm. The algorithm provides the technical support for the practical application of MIMO radar. PMID:29518957

Multi-Target Angle Tracking Algorithm for Bistatic Multiple-Input Multiple-Output (MIMO) Radar Based on the Elements of the Covariance Matrix.

PubMed

Zhang, Zhengyan; Zhang, Jianyun; Zhou, Qingsong; Li, Xiaobo

2018-03-07

In this paper, we consider the problem of tracking the direction of arrivals (DOA) and the direction of departure (DOD) of multiple targets for bistatic multiple-input multiple-output (MIMO) radar. A high-precision tracking algorithm for target angle is proposed. First, the linear relationship between the covariance matrix difference and the angle difference of the adjacent moment was obtained through three approximate relations. Then, the proposed algorithm obtained the relationship between the elements in the covariance matrix difference. On this basis, the performance of the algorithm was improved by averaging the covariance matrix element. Finally, the least square method was used to estimate the DOD and DOA. The algorithm realized the automatic correlation of the angle and provided better performance when compared with the adaptive asymmetric joint diagonalization (AAJD) algorithm. The simulation results demonstrated the effectiveness of the proposed algorithm. The algorithm provides the technical support for the practical application of MIMO radar.

Magnesium silicide nanoparticles as a deoxygenation agent for cancer starvation therapy

NASA Astrophysics Data System (ADS)

Zhang, Chen; Ni, Dalong; Liu, Yanyan; Yao, Heliang; Bu, Wenbo; Shi, Jianlin

2017-05-01

A material that rapidly absorbs molecular oxygen (known as an oxygen scavenger or deoxygenation agent (DOA)) has various industrial applications, such as in food preservation, anticorrosion of metal and coal deoxidation. Given that oxygen is vital to cancer growth, to starve tumours through the consumption of intratumoral oxygen is a potentially useful strategy in fighting cancer. Here we show that an injectable polymer-modified magnesium silicide (Mg2Si) nanoparticle can act as a DOA by scavenging oxygen in tumours and form by-products that block tumour capillaries from being reoxygenated. The nanoparticles are prepared by a self-propagating high-temperature synthesis strategy. In the acidic tumour microenvironment, the Mg2Si releases silane, which efficiently reacts with both tissue-dissolved and haemoglobin-bound oxygen to form silicon oxide (SiO2) aggregates. This in situ formation of SiO2 blocks the tumour blood capillaries and prevents tumours from receiving new supplies of oxygen and nutrients.

Magnesium silicide nanoparticles as a deoxygenation agent for cancer starvation therapy.

PubMed

Zhang, Chen; Ni, Dalong; Liu, Yanyan; Yao, Heliang; Bu, Wenbo; Shi, Jianlin

2017-05-01

A material that rapidly absorbs molecular oxygen (known as an oxygen scavenger or deoxygenation agent (DOA)) has various industrial applications, such as in food preservation, anticorrosion of metal and coal deoxidation. Given that oxygen is vital to cancer growth, to starve tumours through the consumption of intratumoral oxygen is a potentially useful strategy in fighting cancer. Here we show that an injectable polymer-modified magnesium silicide (Mg 2 Si) nanoparticle can act as a DOA by scavenging oxygen in tumours and form by-products that block tumour capillaries from being reoxygenated. The nanoparticles are prepared by a self-propagating high-temperature synthesis strategy. In the acidic tumour microenvironment, the Mg 2 Si releases silane, which efficiently reacts with both tissue-dissolved and haemoglobin-bound oxygen to form silicon oxide (SiO 2 ) aggregates. This in situ formation of SiO 2 blocks the tumour blood capillaries and prevents tumours from receiving new supplies of oxygen and nutrients.

Electroencephalogram-based indices applied to dogs' depth of anaesthesia monitoring.

PubMed

Brás, S; Georgakis, A; Ribeiro, L; Ferreira, D A; Silva, A; Antunes, L; Nunes, C S

2014-12-01

Hypnotic drug administration causes alterations in the electroencephalogram (EEG) in a dose-dependent manner. These changes cannot be identified easily in the raw EEG, therefore EEG based indices were adopted for assessing depth of anaesthesia (DoA). This study examines several indices for estimating dogs' DoA. Data (EEG, clinical end-points) were collected from 8 dogs anaesthetized with propofol. EEG was initially collected without propofol. Then, 100 ml h⁻¹ (1000 mg h⁻¹) of propofol 1% infusion rate was administered until a deep anaesthetic stage was reached. The infusion rate was temporarily increased to 200 ml h⁻¹ (2000 mg h⁻¹) to achieve 80% of burst suppression. The index performance was accessed by correlation coefficient with the propofol concentrations, and prediction probability with the anaesthetic clinical end-points. The temporal entropy and the averaged instantaneous frequency were the best indices because they exhibit: (a) strong correlations with propofol concentrations, (b) high probabilities of predicting anaesthesia clinical end-points. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improving transport container design to reduce broiler chicken PSE (pale, soft, exudative) meat in Brazil.

PubMed

Spurio, Rafael S; Soares, Adriana L; Carvalho, Rafael H; Silveira Junior, Vivaldo; Grespan, Moisés; Oba, Alexandre; Shimokomaki, Massami

2016-02-01

Throughout the chicken production chain, transport from farm to the commercial abattoir is one of the most critical sources of stress, particularly heat stress. The aim of this work was to describe the performance of a new prototype truck container designed to improve the microenvironment and reduce the incidence of pale, soft and exudative (PSE) meat and dead on arrival (DOA) occurrences. Experiments were carried out for four different conditions: regular and prototype truck, both with and without wetting loaded cages at the farm (for bird thermal stress relief) just before transporting. While there was no difference in the DOA index (P ≥ 0.05), the prototype truck caused a reduction (P < 0.05) in the occurrence of PSE meat by 66.3% and 49.6% with and without wetting, respectively. The results of this experiment clearly revealed a low-cost solution for transporting chickens that yields better animal welfare conditions and improves meat quality. © 2015 Japanese Society of Animal Science.

Characterization of exhaust emissions from diesel-powered passenger cars with particular reference to unregulated components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lies, K.H.; Postulka, A.; Gring, H.

Besides regulated components VW's research program in the field of characterization of diesel emissions comprises a detailed analysis of the particulates and a comprehensive study of a number of unregulated gaseous compounds. The following chemical compounds and classes of compounds are measured: particulates, traces of metals, major elements, sulfates, sulfur dioxide, hydrogen sulfide, hydrogen cyanide, aldehydes, ammonia, phenols, individual hydrocarbons, and odor (DOAS). The test fleet of this investigation included a number of VW and Audi cars equipped with 4-, and 5-cylinder diesel engines (naturally aspirated and turbocharged). All measurements were performed on a chassis dynamometer in accordance with themore » specification of the known US-test-procedures: Federal Test Procedure, Sulfate Emission Test, Fuel Economy Test. For sampling , in principle, the dilution tunnel technique was used combined with an automatically working collection system. This micro-processor controlled system involves 13 individual sample lines, 8 for gaseous and 5 for particulate components.« less

The hot DOA1 degenerate HZ 21 - A search for circumstellar/photospheric metals and peculiar absorption at He II

NASA Technical Reports Server (NTRS)

Fritz, M. L.; Leckenby, H.; Sion, E. M.; Vauclair, G.; Liebert, J.

1990-01-01

A high-resolution IUE spectrum of the hot DO1 degenerate HZ 21 was obtained by combining US1 + European 2 low-background observing shifts. The SWP image reveals a rich spectrum of interstellar absorption lines with an average velocity in the line of sight to HZ 21 of -30 km/s. However, there is no clear evidence of any highly or lowly ionized metal features which could be attributed to circumstellar, wind, or photospheric absorption. There is, however, a broad absorption trough at He II (1640) which was not unexpected, given the clear presence of He II (4686) absorption in this star's optical spectrum. The velocity width of He II (1640) appears consistent with photospheric absorption wings which appear to flank the geocoronal Ly-alpha emission feature. The He II (1640) feature reveals what appears to be a broad (310 km/s) emission reversal. Evidence is provided that the emission reversal is probably real.

Decision Topology Assessment in Engineering Design Under Uncertainity

DTIC Science & Technology

2014-01-01

those of the United States Government or the DoA, and shall not be used for advertising or product endorsement purposes. REFERENCES 1. Clemen ...Raiffa, H., 1994, Decisions with Multiple Objectives, Cambridge University Press, Cambridge, United Kingdom. 6. Lewis, K., W. Chen, and L.C. Schmidt

Tropospheric nitrogen dioxide column retrieval from ground-based zenith-sky DOAS observations

NASA Astrophysics Data System (ADS)

Tack, F.; Hendrick, F.; Goutail, F.; Fayt, C.; Merlaud, A.; Pinardi, G.; Hermans, C.; Pommereau, J.-P.; Van Roozendael, M.

2015-01-01

We present an algorithm for retrieving tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs) from ground-based zenith-sky (ZS) measurements of scattered sunlight. The method is based on a four-step approach consisting of (1) the Differential Optical Absorption Spectroscopy (DOAS) analysis of ZS radiance spectra using a fixed reference spectrum corresponding to low NO2 absorption, (2) the determination of the residual amount in the reference spectrum using a Langley-plot-type method, (3) the removal of the stratospheric content from the daytime total measured slant column based on stratospheric VCDs measured at sunrise and sunset, and simulation of the rapid NO2 diurnal variation, (4) the retrieval of tropospheric VCDs by dividing the resulting tropospheric slant columns by appropriate air mass factors (AMFs). These steps are fully characterized and recommendations are given for each of them. The retrieval algorithm is applied on a ZS dataset acquired with a Multi-AXis (MAX-) DOAS instrument during the Cabauw (51.97° N, 4.93° E, sea level) Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI) held from the 10 June to the 21 July 2009 in the Netherlands. A median value of 7.9 × 1015 molec cm-2 is found for the retrieved tropospheric NO2 VCDs, with maxima up to 6.0 × 1016 molec cm-2. The error budget assessment indicates that the overall error σTVCD on the column values is less than 28%. In case of low tropospheric contribution, σTVCD is estimated to be around 39% and is dominated by uncertainties in the determination of the residual amount in the reference spectrum. For strong tropospheric pollution events, σTVCD drops to approximately 22% with the largest uncertainties on the determination of the stratospheric NO2 abundance and tropospheric AMFs. The tropospheric VCD amounts derived from ZS observations are compared to VCDs retrieved from off-axis and direct-sun measurements of the same MAX-DOAS instrument as well as to data from a co-located Système d'Analyse par Observations Zénithales (SAOZ) spectrometer. The retrieved tropospheric VCDs are in good agreement with the different datasets with correlation coefficients and slopes close to or larger than 0.9. The potential of the presented ZS retrieval algorithm is further demonstrated by its successful application on a 2 year dataset, acquired at the NDACC (Network for the Detection of Atmospheric Composition Change) station Observatoire de Haute Provence (OHP; Southern France).

Tropospheric nitrogen dioxide column retrieval from ground-based zenith-sky DOAS observations

NASA Astrophysics Data System (ADS)

Tack, F.; Hendrick, F.; Goutail, F.; Fayt, C.; Merlaud, A.; Pinardi, G.; Hermans, C.; Pommereau, J.-P.; Van Roozendael, M.

2015-06-01

We present an algorithm for retrieving tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs) from ground-based zenith-sky (ZS) measurements of scattered sunlight. The method is based on a four-step approach consisting of (1) the differential optical absorption spectroscopy (DOAS) analysis of ZS radiance spectra using a fixed reference spectrum corresponding to low NO2 absorption, (2) the determination of the residual amount in the reference spectrum using a Langley-plot-type method, (3) the removal of the stratospheric content from the daytime total measured slant column based on stratospheric VCDs measured at sunrise and sunset, and simulation of the rapid NO2 diurnal variation, (4) the retrieval of tropospheric VCDs by dividing the resulting tropospheric slant columns by appropriate air mass factors (AMFs). These steps are fully characterized and recommendations are given for each of them. The retrieval algorithm is applied on a ZS data set acquired with a multi-axis (MAX-) DOAS instrument during the Cabauw (51.97° N, 4.93° E, sea level) Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI) held from 10 June to 21 July 2009 in the Netherlands. A median value of 7.9 × 1015 molec cm-2 is found for the retrieved tropospheric NO2 VCDs, with maxima up to 6.0 × 1016 molec cm-2. The error budget assessment indicates that the overall error σTVCD on the column values is less than 28%. In the case of low tropospheric contribution, σTVCD is estimated to be around 39% and is dominated by uncertainties in the determination of the residual amount in the reference spectrum. For strong tropospheric pollution events, σTVCD drops to approximately 22% with the largest uncertainties on the determination of the stratospheric NO2 abundance and tropospheric AMFs. The tropospheric VCD amounts derived from ZS observations are compared to VCDs retrieved from off-axis and direct-sun measurements of the same MAX-DOAS instrument as well as to data from a co-located Système d'Analyse par Observations Zénithales (SAOZ) spectrometer. The retrieved tropospheric VCDs are in good agreement with the different data sets with correlation coefficients and slopes close to or larger than 0.9. The potential of the presented ZS retrieval algorithm is further demonstrated by its successful application on a 2-year data set, acquired at the NDACC (Network for the Detection of Atmospheric Composition Change) station Observatoire de Haute Provence (OHP; Southern France).

12 CFR 313.4 - Delegations of authority.

Code of Federal Regulations, 2010 CFR

2010-01-01

... CORPORATE DEBT COLLECTION Scope, Purpose, Definitions and Delegations of Authority § 313.4 Delegations of... debt, on behalf of the FDIC in its corporate capacity is delegated to the Director of DOA or Director... either its receivership or corporate capacity is delegated to the Director of DRR; or to the applicable...

Estimation of Target Angular Position Under Mainbeam Jamming Conditions,

DTIC Science & Technology

1995-12-01

technique, Multiple Signal Classification ( MUSIC ), is used to estimate the target Direction Of Arrival (DOA) from the processed data vectors. The model...used in the MUSIC technique takes into account the fact that the jammer has been cancelled in the target data vector. The performance of this algorithm

Examination of temporal and spatial variability of NO2 VCDs measured using mobile-MAX-DOAS in Toronto, Canada.

NASA Astrophysics Data System (ADS)

Davis, Zoe; Baray, Sabour; Khanbabkhani, Aida; Fujs, William; Csukat, Csilla; McLaren, Robert

2017-04-01

Mobile-MAX-DOAS is an innovative technique used to estimate pollutant emission rates and validate satellite measurements and air quality models. It is essential to identify and examine factors that can significantly impact the accuracy of this developing technique. Mobile-MAX-DOAS measurements were conducted in Toronto, Canada with a mini-MAX-DOAS instrument mounted (pointing backwards) on top of a car during August and September, 2016. Scattered sunlight spectra were collected every 45 seconds in the continuously repeated sequence of elevation angles of 30o, 30o, 30o, 30o, 40o, 30o, 90o. Tropospheric VCDs were determined using the geometric approximation from DSCDs fitted using a near-noon, low NO2 VCD FRS spectrum. The study goal was to examine the validity of the assumption that VCDs remain relatively constant at each measured location on a driving route encircling an urban area of interest with typical time periods of 1.5-3 hours to estimate emissions and whether driving direction significantly impacts results. NO2 VCD temporal variability was therefore determined by repeating driving routes in both directions in quick succession on multiple days. Strong temporal variability in NO2 VCDs of up to a factor of two were observed for some routes for the same vehicle locations under constant prevailing wind conditions within <2 hours. These differences may be due to the effects of transport, changing tropospheric chemistry and/or diurnal trends in emissions rates. Under these conditions measurements along different portions of the encircled area in a large city may not be representative of the entire measurement period, introducing error into the final emission estimate. Certain straight roads exhibited significantly different VCDs within < 30 minutes when the instrument azimuth pointing direction was changed by 180o. The weighted average VCD was ˜8(±3x) x1016molec. cm-1 from driving in one direction but ˜4 (± 1.5) x1016molec. cm-1 from driving in the opposite direction. This indicates sufficient horizontal inhomogeneity for the instrument to view significantly different NO2 regimes while at the same vehicle geographical location due to the different azimuth direction. NO2line fluxes were determined during weekday afternoon rush-hours by driving repeatedly in both directions under tangential prevailing winds conditions on a road that is 8km downwind of Toronto and 4km downwind of a major highway. During one afternoon the average NO2 VCD was 6(±2)x1016 molec. cm-2with a standard deviation of 3x1015 molec. cm-2. This average value is consistent with NO2 VCDs retrieved using optimal estimation methods from stationary MAX-DOAS measurements at nearby York University. Using a 10m elevation measured wind-speed of 16km hr-1, the NO2 line flux was 3(± 9) x1018molec. cm-1s-1, approximately 6 times that determined by Halla et al. (2011) for a line flux measured in a rural area of southwestern Ontario, downwind of pollution sources in Michigan and Ohio. Our resulting average NO2 flux of 84 (+/-25) mg m-2hr-1 is consistent with NOx fluxes measured in major European cities of up to 90 mg m-2hr-1. This work will be used as a baseline experiment to apply this method in other Canadian cities.

77 FR 4947 - Proposed Significant New Use Rules on Certain Chemical Substances; Reopening of Comment Period

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-01

...), Office of Pollution Prevention and Toxics, Environmental Protection Agency, 1200 Pennsylvania Ave. NW... requirements. Dated: January 24, 2012. Maria J. Doa, Director, Chemical Control Division, Office of Pollution Prevention and Toxics. [FR Doc. 2012-2200 Filed 1-31-12; 8:45 am] BILLING CODE 6560-50-P ...

The Exercise: An Exercise Generator Tool for the SOURCe Project

ERIC Educational Resources Information Center

Kakoyianni-Doa, Fryni; Tziafa, Eleni; Naskos, Athanasios

2016-01-01

The Exercise, an Exercise generator in the SOURCe project, is a tool that complements the properties and functionalities of the SOURCe project, which includes the search engine for the Searchable Online French-Greek parallel corpus for the UniveRsity of Cyprus (SOURCe) (Kakoyianni-Doa & Tziafa, 2013), the PENCIL (an alignment tool)…

40 CFR 272.951 - Louisiana State-Administered Program: Final Authorization.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., Baton Rouge, LA 70804-9095; Phone number: (225) 342-5015; Web site: http://doa.louisiana.gov/osr/lac/lac.... Paul, Minnesota 55164-0526; Phone: 1-800-328-4880; Web site: http://west.thomson.com. You may inspect a... National Archives and Records Administration (NARA). For information on the availability of this material...

40 CFR 272.951 - Louisiana state-administered Program: Final authorization.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., Baton Rouge, LA 70804-9095; Phone number: (225) 342-5015; Web site: http://doa.louisiana.gov/osr/lac/lac.... Paul, Minnesota 55164 0526; Phone: 1-800-328-4880; Web site: http://west.thomson.com. You may inspect a... National Archives and Records Administration (NARA). For information on the availability of this material...

77 FR 61583 - Privacy Act of 1974; System of Records; Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-10

... A0351 AMC, Student/Faculty Records: AMC Schools Systems, as the records had been transferred to the... discovered that the records had not yet been transferred to TRADOC. Therefore, the DOA systems of records notice cannot be deleted at this time. DATES: This correction is effective October 10, 2012. FOR FURTHER...

An interface for simulating radiative transfer in and around volcanic plumes with the Monte Carlo radiative transfer model McArtim

USGS Publications Warehouse

Kern, Christoph

2016-03-23

This report describes two software tools that, when used as front ends for the three-dimensional backward Monte Carlo atmospheric-radiative-transfer model (RTM) McArtim, facilitate the generation of lookup tables of volcanic-plume optical-transmittance characteristics in the ultraviolet/visible-spectral region. In particular, the differential optical depth and derivatives thereof (that is, weighting functions), with regard to a change in SO2 column density or aerosol optical thickness, can be simulated for a specific measurement geometry and a representative range of plume conditions. These tables are required for the retrieval of SO2 column density in volcanic plumes, using the simulated radiative-transfer/differential optical-absorption spectroscopic (SRT-DOAS) approach outlined by Kern and others (2012). This report, together with the software tools published online, is intended to make this sophisticated SRT-DOAS technique available to volcanologists and gas geochemists in an operational environment, without the need for an indepth treatment of the underlying principles or the low-level interface of the RTM McArtim.

A GC-MS method for the detection and quantitation of ten major drugs of abuse in human hair samples.

PubMed

Orfanidis, A; Mastrogianni, O; Koukou, A; Psarros, G; Gika, H; Theodoridis, G; Raikos, N

2017-03-15

A sensitive analytical method has been developed in order to identify and quantify major drugs of abuse (DOA), namely morphine, codeine, 6-monoacetylmorphine, cocaine, ecgonine methyl ester, benzoylecgonine, amphetamine, methamphetamine, methylenedioxymethamphetamine and methylenedioxyamphetamine in human hair. Samples of hair were extracted with methanol under ultrasonication at 50°C after a three step rinsing process to remove external contamination and dirt hair. Derivatization with BSTFA was selected in order to increase detection sensitivity of GC/MS analysis. Optimization of derivatization parameters was based on experiments for the selection of derivatization time, temperature and volume of derivatising agent. Validation of the method included evaluation of linearity which ranged from 2 to 350ng/mg of hair mean concentration for all DOA, evaluation of sensitivity, accuracy, precision and repeatability. Limits of detection ranged from 0.05 to 0.46ng/mg of hair. The developed method was applied for the analysis of hair samples obtained from three human subjects and were found positive in cocaine, and opiates. Published by Elsevier B.V.

Fast super-resolution estimation of DOA and DOD in bistatic MIMO Radar with off-grid targets

NASA Astrophysics Data System (ADS)

Zhang, Dong; Zhang, Yongshun; Zheng, Guimei; Feng, Cunqian; Tang, Jun

2018-05-01

In this paper, we focus on the problem of joint DOA and DOD estimation in Bistatic MIMO Radar using sparse reconstruction method. In traditional ways, we usually convert the 2D parameter estimation problem into 1D parameter estimation problem by Kronecker product which will enlarge the scale of the parameter estimation problem and bring more computational burden. Furthermore, it requires that the targets must fall on the predefined grids. In this paper, a 2D-off-grid model is built which can solve the grid mismatch problem of 2D parameters estimation. Then in order to solve the joint 2D sparse reconstruction problem directly and efficiently, three kinds of fast joint sparse matrix reconstruction methods are proposed which are Joint-2D-OMP algorithm, Joint-2D-SL0 algorithm and Joint-2D-SOONE algorithm. Simulation results demonstrate that our methods not only can improve the 2D parameter estimation accuracy but also reduce the computational complexity compared with the traditional Kronecker Compressed Sensing method.

Design of differential optical absorption spectroscopy long-path telescopes based on fiber optics.

PubMed

Merten, André; Tschritter, Jens; Platt, Ulrich

2011-02-10

We present a new design principle of telescopes for use in the spectral investigation of the atmosphere and the detection of atmospheric trace gases with the long-path differential optical absorption spectroscopy (DOAS) technique. A combination of emitting and receiving fibers in a single bundle replaces the commonly used coaxial-Newton-type combination of receiving and transmitting telescope. This very simplified setup offers a higher light throughput and simpler adjustment and allows smaller instruments, which are easier to handle and more portable. The higher transmittance was verified by ray-tracing calculations, which result in a theoretical factor threefold improvement in signal intensity compared with the old setup. In practice, due to the easier alignment and higher stability, up to factor of 10 higher signal intensities were found. In addition, the use of a fiber optic light source provides a better spectral characterization of the light source, which results in a lower detection limit for trace gases studied with this instrument. This new design will greatly enhance the usability and the range of applications of active DOAS instruments.

Multiple-Parameter Estimation Method Based on Spatio-Temporal 2-D Processing for Bistatic MIMO Radar

PubMed Central

Yang, Shouguo; Li, Yong; Zhang, Kunhui; Tang, Weiping

2015-01-01

A novel spatio-temporal 2-dimensional (2-D) processing method that can jointly estimate the transmitting-receiving azimuth and Doppler frequency for bistatic multiple-input multiple-output (MIMO) radar in the presence of spatial colored noise and an unknown number of targets is proposed. In the temporal domain, the cross-correlation of the matched filters’ outputs for different time-delay sampling is used to eliminate the spatial colored noise. In the spatial domain, the proposed method uses a diagonal loading method and subspace theory to estimate the direction of departure (DOD) and direction of arrival (DOA), and the Doppler frequency can then be accurately estimated through the estimation of the DOD and DOA. By skipping target number estimation and the eigenvalue decomposition (EVD) of the data covariance matrix estimation and only requiring a one-dimensional search, the proposed method achieves low computational complexity. Furthermore, the proposed method is suitable for bistatic MIMO radar with an arbitrary transmitted and received geometrical configuration. The correction and efficiency of the proposed method are verified by computer simulation results. PMID:26694385

Multiple-Parameter Estimation Method Based on Spatio-Temporal 2-D Processing for Bistatic MIMO Radar.

PubMed

Yang, Shouguo; Li, Yong; Zhang, Kunhui; Tang, Weiping

2015-12-14

A novel spatio-temporal 2-dimensional (2-D) processing method that can jointly estimate the transmitting-receiving azimuth and Doppler frequency for bistatic multiple-input multiple-output (MIMO) radar in the presence of spatial colored noise and an unknown number of targets is proposed. In the temporal domain, the cross-correlation of the matched filters' outputs for different time-delay sampling is used to eliminate the spatial colored noise. In the spatial domain, the proposed method uses a diagonal loading method and subspace theory to estimate the direction of departure (DOD) and direction of arrival (DOA), and the Doppler frequency can then be accurately estimated through the estimation of the DOD and DOA. By skipping target number estimation and the eigenvalue decomposition (EVD) of the data covariance matrix estimation and only requiring a one-dimensional search, the proposed method achieves low computational complexity. Furthermore, the proposed method is suitable for bistatic MIMO radar with an arbitrary transmitted and received geometrical configuration. The correction and efficiency of the proposed method are verified by computer simulation results.

Sterol homeostasis requires regulated degradation of squalene monooxygenase by the ubiquitin ligase Doa10/Teb4

PubMed Central

Foresti, Ombretta; Ruggiano, Annamaria; Hannibal-Bach, Hans K; Ejsing, Christer S; Carvalho, Pedro

2013-01-01

Sterol homeostasis is essential for the function of cellular membranes and requires feedback inhibition of HMGR, a rate-limiting enzyme of the mevalonate pathway. As HMGR acts at the beginning of the pathway, its regulation affects the synthesis of sterols and of other essential mevalonate-derived metabolites, such as ubiquinone or dolichol. Here, we describe a novel, evolutionarily conserved feedback system operating at a sterol-specific step of the mevalonate pathway. This involves the sterol-dependent degradation of squalene monooxygenase mediated by the yeast Doa10 or mammalian Teb4, a ubiquitin ligase implicated in a branch of the endoplasmic reticulum (ER)-associated protein degradation (ERAD) pathway. Since the other branch of ERAD is required for HMGR regulation, our results reveal a fundamental role for ERAD in sterol homeostasis, with the two branches of this pathway acting together to control sterol biosynthesis at different levels and thereby allowing independent regulation of multiple products of the mevalonate pathway. DOI: http://dx.doi.org/10.7554/eLife.00953.001 PMID:23898401

Retrieval and Analysis of Stratospheric NO2 from GOME

NASA Technical Reports Server (NTRS)

Wenig, M.; Kuehl, S.; Beirle, S.; Wagner, T.; Jaehne, B.; Platt, U.

2003-01-01

In this paper we describe the retrieval of stratospheric NO2 from the GOME (Global Ozone Monitoring Experiment) spectrometer. For this retrieval the Differential Optical Absorption Spectroscopy (DOAS) is used and we describe the influence of the instrument s characteristics on this measurement technique. This analysis led to an improved version of the DOAS algorithm resulting in results with lower systematic errors. Subsequently these results were used to separate the tropospheric and stratospheric fraction of the measured NO;! in the atmosphere. This paper is focusing on the annual variations of the stratospheric distribution of nitrogen oxides. For this examination the satellite data from beginning of 1996 to the end of 2001 was used and has been visualized in a plot zonal means versus time of the year, a visualization which proved to be very useful for Ozone. Additionally the so called "Noxon Cliff", a drop of NO2 column densities Noxon measured in 1975-77 while traveling northwards towards the pole in Canada, is shown. Also its southern equivalent could be discovered in the GOME data.

A Tensor-Based Subspace Approach for Bistatic MIMO Radar in Spatial Colored Noise

PubMed Central

Wang, Xianpeng; Wang, Wei; Li, Xin; Wang, Junxiang

2014-01-01

In this paper, a new tensor-based subspace approach is proposed to estimate the direction of departure (DOD) and the direction of arrival (DOA) for bistatic multiple-input multiple-output (MIMO) radar in the presence of spatial colored noise. Firstly, the received signals can be packed into a third-order measurement tensor by exploiting the inherent structure of the matched filter. Then, the measurement tensor can be divided into two sub-tensors, and a cross-covariance tensor is formulated to eliminate the spatial colored noise. Finally, the signal subspace is constructed by utilizing the higher-order singular value decomposition (HOSVD) of the cross-covariance tensor, and the DOD and DOA can be obtained through the estimation of signal parameters via rotational invariance technique (ESPRIT) algorithm, which are paired automatically. Since the multidimensional inherent structure and the cross-covariance tensor technique are used, the proposed method provides better angle estimation performance than Chen's method, the ESPRIT algorithm and the multi-SVD method. Simulation results confirm the effectiveness and the advantage of the proposed method. PMID:24573313

A differential optical absorption spectroscopy method for retrieval from ground-based Fourier transform spectrometers measurements of the direct solar beam

NASA Astrophysics Data System (ADS)

Huo, Yanfeng; Duan, Minzheng; Tian, Wenshou; Min, Qilong

2015-08-01

A differential optical absorption spectroscopy (DOAS)-like algorithm is developed to retrieve the column-averaged dryair mole fraction of carbon dioxide from ground-based hyper-spectral measurements of the direct solar beam. Different to the spectral fitting method, which minimizes the difference between the observed and simulated spectra, the ratios of multiple channel-pairs—one weak and one strong absorption channel—are used to retrieve from measurements of the shortwave infrared (SWIR) band. Based on sensitivity tests, a super channel-pair is carefully selected to reduce the effects of solar lines, water vapor, air temperature, pressure, instrument noise, and frequency shift on retrieval errors. The new algorithm reduces computational cost and the retrievals are less sensitive to temperature and H2O uncertainty than the spectral fitting method. Multi-day Total Carbon Column Observing Network (TCCON) measurements under clear-sky conditions at two sites (Tsukuba and Bremen) are used to derive xxxx for the algorithm evaluation and validation. The DOAS-like results agree very well with those of the TCCON algorithm after correction of an airmass-dependent bias.

A tensor-based subspace approach for bistatic MIMO radar in spatial colored noise.

PubMed

Wang, Xianpeng; Wang, Wei; Li, Xin; Wang, Junxiang

2014-02-25

In this paper, a new tensor-based subspace approach is proposed to estimate the direction of departure (DOD) and the direction of arrival (DOA) for bistatic multiple-input multiple-output (MIMO) radar in the presence of spatial colored noise. Firstly, the received signals can be packed into a third-order measurement tensor by exploiting the inherent structure of the matched filter. Then, the measurement tensor can be divided into two sub-tensors, and a cross-covariance tensor is formulated to eliminate the spatial colored noise. Finally, the signal subspace is constructed by utilizing the higher-order singular value decomposition (HOSVD) of the cross-covariance tensor, and the DOD and DOA can be obtained through the estimation of signal parameters via rotational invariance technique (ESPRIT) algorithm, which are paired automatically. Since the multidimensional inherent structure and the cross-covariance tensor technique are used, the proposed method provides better angle estimation performance than Chen's method, the ESPRIT algorithm and the multi-SVD method. Simulation results confirm the effectiveness and the advantage of the proposed method.

Wall interference tests of a CAST 10-2/DOA 2 airfoil in an adaptive-wall test section

NASA Technical Reports Server (NTRS)

Mineck, Raymond E.

1987-01-01

A wind-tunnel investigation of a CAST 10-2/DOA 2 airfoil model has been conducted in the adaptive-wall test section of the Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT) and in the National Aeronautical Establishment High Reynolds Number Two-Dimensional Test Facility. The primary goal of the tests was to assess two different wall-interference correction techniques: adaptive test-section walls and classical analytical corrections. Tests were conducted over a Mach number range from 0.3 to 0.8 and over a chord Reynolds number range from 6 million to 70 million. The airfoil aerodynamic characteristics from the tests in the 0.3-m TCT have been corrected for wall interference by the movement of the adaptive walls. No additional corrections for any residual interference have been applied to the data, to allow comparison with the classically corrected data from the same model in the conventional National Aeronautical Establishment facility. The data are presented graphically in this report as integrated force-and-moment coefficients and chordwise pressure distributions.

NO2 fluxes from Tijuana using a mobile mini-DOAS during Cal-Mex 2010

NASA Astrophysics Data System (ADS)

Rivera, Claudia; Barrera, Hugo; Grutter, Michel; Zavala, Miguel; Galle, Bo; Bei, Naifang; Li, Guohui; Molina, Luisa T.

2013-05-01

NO2 fluxes were measured using a mobile mini-DOAS during Cal-Mex 2010 field study, between May 15 and June 30, 2010, from the urban area of Tijuana, Baja California as well as the Rosarito power plant. The average calculated NO2 fluxes were 328 ± 184 (269 ± 201) g s-1, and 23.4 ± 4.9 (12.9 ± 11.9) g s-1 for Tijuana urban area and Rosarito power plant, respectively, using model based wind fields and onsite measurements (in parenthesis). Wind speed and wind direction data needed to estimate the fluxes were both modeled and obtained from radiosondes launched regularly during the field campaign, whereas the mixing layer height throughout the entire field campaign was measured using a ceilometer. Large variations in the NO2 fluxes from both the Tijuana urban area and Rosarito power plant were observed during Cal-Mex 2010; however, the variability was less when model based wind fields were used. Qualitative comparisons of modeled and measured plumes from the Tijuana urban area and Rosarito power plant showed good agreement.

Forest Fire Finder - DOAS application to long-range forest fire detection

NASA Astrophysics Data System (ADS)

Valente de Almeida, Rui; Vieira, Pedro

2017-06-01

Fires are an important factor in shaping Earth's ecosystems. Plant and animal life, in almost every land habitat, are at least partially dependent on the effects of fire. However, their destructive force, which has often proven uncontrollable, is one of our greatest concerns, effectively resulting in several policies in the most important industrialised regions of the globe. This paper aims to comprehensively characterise the Forest Fire Finder (FFF), a forest fire detection system based mainly upon a spectroscopic technique called differential optical absorption spectroscopy (DOAS). The system is designed and configured with the goal of detecting higher-than-the-horizon smoke columns by measuring and comparing scattered sunlight spectra. The article covers hardware and software, as well as their interactions and specific algorithms for day mode operation. An analysis of data retrieved from several installations deployed in the course of the last 5 years is also presented. Finally, this paper features a discussion on the most prominent future improvements planned for the system, as well as its ramifications and adaptations, such as a thermal imaging system for short-range fire seeking or environmental quality control.

Tomographic multiaxis-differential optical absorption spectroscopy observations of Sun-illuminated targets: a technique providing well-defined absorption paths in the boundary layer

NASA Astrophysics Data System (ADS)

Frins, Erna; Bobrowski, Nicole; Platt, Ulrich; Wagner, Thomas

2006-08-01

A novel experimental procedure to measure the near-surface distribution of atmospheric trace gases by using passive multiaxis differential absorption optical spectroscopy (MAX-DOAS) is proposed. The procedure consists of pointing the receiving telescope of the spectrometer to nonreflecting surfaces or to bright targets placed at known distances from the measuring device, which are illuminated by sunlight. We show that the partial trace gas absorptions between the top of the atmosphere and the target can be easily removed from the measured total absorption. Thus it is possible to derive the average concentration of trace gases such as NO2, HCHO, SO2, H2O, Glyoxal, BrO, and others along the line of sight between the instrument and the target similar to the well-known long-path DOAS observations (but with much less expense). If tomographic arrangements are used, even two- or three-dimensional trace gas distributions can be retrieved. The basic assumptions of the proposed method are confirmed by test measurements taken across the city of Heidelberg.

Infrasonic signatures of a Polar Low in the Norwegian and Barents Sea on 23 27 March 1992

NASA Astrophysics Data System (ADS)

Børre Orbæk, Jon; Naustvik, Magnus

1995-10-01

This article presents an analysis of a Polar Low in the Norwegian and Barents Sea, 23 27 March 1992. The low is remote monitored from northern Norway and Svalbard by means of two Passive Broadband Infrasonic Sodars (PBIS's), estimating the directionality of the local acoustic field of atmospheric infrasound. The presented data show that the polar low apparently generates strong infrasound, and it is believed that some part of the measured pressure perturbations are generated by the intense turbulent regions of the low, as part of the aerodynamic spectrum. Due to the very low attenuation of infrasound in the atmosphere, the sound propagates to distant recording stations more than 1000km away, by successive reflections between the upper atmosphere and the sea surface. Because of the small number of synoptic stations in the area, data inputs to the numerical circulation models are few, and because the phenomena in study are mesoscale, down to one tenth the size of a frontal cyclone, conventional meteorological data may not resolve the features of interest. The infrasonic direction-of-arrival (DOA)-spectra produced by the PBIS passive acoustic remote sensing technique utilized in this work, is shown to give new information to the analysis of the weather situation. While the satellite images normally are ambiguous with respect to the dynamics and thermodynamic state of the visible cloud-clusters, the infrasonic DOA-spectra may provide valuable dynamic information of the distant polar low in near real time. It is suggested that the major part of the infrasonic signatures detected by the PBIS's come from the active regions of turbulent convection. By picking out the directions of these active intensification regions, the DOA-spectra may, as is shown in this article, indicate that several local disturbances took part in the complex polar low development.

Multi-year MAX-DOAS observations of formaldehyde and glyoxal in Phimai, Thailand

NASA Astrophysics Data System (ADS)

Hoque, H. M. S.; Irie, H.; Shimizu, A.; Damiani, A.

2017-12-01

The first long-term Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations were performed in Phimai, Thailand (15.18 °N, 102.56 °E), a site in Southeast Asia, where ground-based remote sensing observations of trace gases and aerosols are very limited. Vertical profile information of eight components was retrieved independently using the Japanese MAX-DOAS profile retrieval algorithm, version 2 (JM2). Here we focus on the two organic compounds, formaldehyde (HCHO) and glyoxal (CHOCHO), and study their volume mixing ratio data in the lowest layer (0-1 km) of our retrieved vertical profiles. In addition to the systematic climatological analysis of HCHO and CHOCHO, we also report the ratio of CHOCHO to HCHO, RGF, which is suggested to be an important tracer of changes of the volatile organic compound (VOC) emission sources. Higher concentration of HCHO and CHOCHO was observed during the dry season (January-April), whereas the concentration level was close to the background level during the wet season (June-September). Such enhancements correspond well the influence of the pronounced seasonal variation of biomass burning activity. The RGF for the Phimai site was estimated to be 0.030±0.010. Our estimated RGF during the dry season ( 0.025±0.008) was lower than that in the wet season ( 0.033±0.012). This change in the RGF is consistent with the satellite retrievals, suggesting a higher RGF for strong biogenic emission sources. While the site can be characterized as environment with a low nitrogen dioxide (NO2) concentration level ( 1 ppbv), the impact of biomass burning on the lower RGF during the dry season was confirmed by occasional enhancement of the NO2 level as an anthropogenic tracer. The results are further supported by additional error analyses for the cloud influence. Our findings are expected to be used to reduce model uncertainties related to VOC chemistry and secondary organic aerosol (SOA) formation

Ground-based & satellite DOAS measurements integration for air quality evaluation/forecast management in the frame of QUITSAT Project.

NASA Astrophysics Data System (ADS)

Kostadinov, Ivan; Petritoli, Andrea; Giovanelli, Giorgio; Masieri, Samuele; Premuda, Margarita; Bortoli, Daniele; Ravegnani, Fabrizio; Palazzi, Elisa

The observations of the Earth's atmosphere from space provide excellent opportunities for the exploration of the sophisticated physical-chemical processes on both global and regional scales. The major interest during the last three decades was focused mainly on the stratosphere and the ozone depletion. More recently the continuous improvements of satellite sensors have revealed new opportunities for larger applications of space observations, attracting scientific interest to the lower troposphere and air quality issues. The air quality depends strongly on the anthropogenic activity and therefore regional environmental agencies along with policy makers are in need of appropriate means for its continuous monitoring and control to ensure the adoption of the most appropriate actions. The goal of the pilot project QUITSAT, funded by the Italian Space Agency, is to develop algorithms and procedures for the evaluation and prediction of the air quality in Lombardia and Emilia-Romagna regions (Italy) by means of integrating satellite observations with ground-based in-situ and remote sensing measurements. This work presents dedicated Differential Optical Absorption Spectroscopy (DOAS) measurements performed during the summer of 2007 and the winter of 2008. One of the DOAS instruments operate at Mt.Cimone station (2165m a.s.l) and the other two instruments conducted measurements in/near Bologna (90 m. a.s.l). Different observational geometry was adopted (zenith-sky, multi-axis and long-path) aimed to provide tropospheric NO2 columns and O3, SO2 and HCHO concentrations at ground level as an input data for QUITSAT procedures. Details of the instruments, the radiative transfer model used and the algorithms for retrieving and calculation of the target gases concentrations are presented. The obtained experimental results are correlated with the corresponding ones retrieved from SCIAMACHY /ENVISAT observations during the overpasses above the ground-based instruments. The analysis stresses on the specificity of the satellite and ground-based observations and the importance of the right choice of appropriate scenario for correlative studies.

Evidence That Isoprene Emission Is Not Limited by Cytosolic Metabolites. Exogenous Malate Does Not Invert the Reverse Sensitivity of Isoprene Emission to High [CO2].

PubMed

Rasulov, Bahtijor; Talts, Eero; Bichele, Irina; Niinemets, Ülo

2018-02-01

Isoprene is synthesized via the chloroplastic 2- C -methyl-d-erythritol 4-phosphate/1-deoxy-d-xylulose 5-phosphate pathway (MEP/DOXP), and its synthesis is directly related to photosynthesis, except under high CO 2 concentration, when the rate of photosynthesis increases but isoprene emission decreases. Suppression of MEP/DOXP pathway activity by high CO 2 has been explained either by limited supply of the cytosolic substrate precursor, phospho enol pyruvate (PEP), into chloroplast as the result of enhanced activity of cytosolic PEP carboxylase or by limited supply of energetic and reductive equivalents. We tested the PEP-limitation hypotheses by feeding leaves with the PEP carboxylase competitive inhibitors malate and diethyl oxalacetate (DOA) in the strong isoprene emitter hybrid aspen ( Populus tremula × Populus tremuloides ). Malate feeding resulted in the inhibition of net assimilation, photosynthetic electron transport, and isoprene emission rates, but DOA feeding did not affect any of these processes except at very high application concentrations. Both malate and DOA did not alter the sensitivity of isoprene emission to high CO 2 concentration. Malate inhibition of isoprene emission was associated with enhanced chloroplastic reductive status that suppressed light reactions of photosynthesis, ultimately leading to reduced isoprene substrate dimethylallyl diphosphate pool size. Additional experiments with altered oxygen concentrations in conditions of feedback-limited and non-feedback-limited photosynthesis further indicated that changes in isoprene emission rate in control and malate-inhibited leaves were associated with changes in the share of ATP and reductive equivalent supply for isoprene synthesis. The results of this study collectively indicate that malate importantly controls the chloroplast reductive status and, thereby, affects isoprene emission, but they do not support the hypothesis that cytosolic metabolite availability alters the response of isoprene emission to changes in atmospheric composition. © 2018 American Society of Plant Biologists. All Rights Reserved.

Quantification and parametrization of non-linearity effects by higher-order sensitivity terms in scattered light differential optical absorption spectroscopy

NASA Astrophysics Data System (ADS)

Puķīte, Jānis; Wagner, Thomas

2016-05-01

We address the application of differential optical absorption spectroscopy (DOAS) of scattered light observations in the presence of strong absorbers (in particular ozone), for which the absorption optical depth is a non-linear function of the trace gas concentration. This is the case because Beer-Lambert law generally does not hold for scattered light measurements due to many light paths contributing to the measurement. While in many cases linear approximation can be made, for scenarios with strong absorptions non-linear effects cannot always be neglected. This is especially the case for observation geometries, for which the light contributing to the measurement is crossing the atmosphere under spatially well-separated paths differing strongly in length and location, like in limb geometry. In these cases, often full retrieval algorithms are applied to address the non-linearities, requiring iterative forward modelling of absorption spectra involving time-consuming wavelength-by-wavelength radiative transfer modelling. In this study, we propose to describe the non-linear effects by additional sensitivity parameters that can be used e.g. to build up a lookup table. Together with widely used box air mass factors (effective light paths) describing the linear response to the increase in the trace gas amount, the higher-order sensitivity parameters eliminate the need for repeating the radiative transfer modelling when modifying the absorption scenario even in the presence of a strong absorption background. While the higher-order absorption structures can be described as separate fit parameters in the spectral analysis (so-called DOAS fit), in practice their quantitative evaluation requires good measurement quality (typically better than that available from current measurements). Therefore, we introduce an iterative retrieval algorithm correcting for the higher-order absorption structures not yet considered in the DOAS fit as well as the absorption dependence on temperature and scattering processes.

Early in-flight detection of SO2 via Differential Optical Absorption Spectroscopy: a feasible aviation safety measure to prevent potential encounters with volcanic plumes

NASA Astrophysics Data System (ADS)

Vogel, L.; Galle, B.; Kern, C.; Delgado Granados, H.; Conde, V.; Norman, P.; Arellano, S.; Landgren, O.; Lübcke, P.; Alvarez Nieves, J. M.; Cárdenas Gonzáles, L.; Platt, U.

2011-09-01

Volcanic ash constitutes a risk to aviation, mainly due to its ability to cause jet engines to fail. Other risks include the possibility of abrasion of windshields and potentially serious damage to avionic systems. These hazards have been widely recognized since the early 1980s, when volcanic ash provoked several incidents of engine failure in commercial aircraft. In addition to volcanic ash, volcanic gases also pose a threat. Prolonged and/or cumulative exposure to sulphur dioxide (SO2) or sulphuric acid (H2SO4) aerosols potentially affects e.g. windows, air frame and may cause permanent damage to engines. SO2 receives most attention among the gas species commonly found in volcanic plumes because its presence above the lower troposphere is a clear proxy for a volcanic cloud and indicates that fine ash could also be present. Up to now, remote sensing of SO2 via Differential Optical Absorption Spectroscopy (DOAS) in the ultraviolet spectral region has been used to measure volcanic clouds from ground based, airborne and satellite platforms. Attention has been given to volcanic emission strength, chemistry inside volcanic clouds and measurement procedures were adapted accordingly. Here we present a set of experimental and model results, highlighting the feasibility of DOAS to be used as an airborne early detection system of SO2 in two spatial dimensions. In order to prove our new concept, simultaneous airborne and ground-based measurements of the plume of Popocatépetl volcano, Mexico, were conducted in April 2010. The plume extended at an altitude around 5250 m above sea level and was approached and traversed at the same altitude with several forward looking DOAS systems aboard an airplane. These DOAS systems measured SO2 in the flight direction and at ±40 mrad (2.3°) angles relative to it in both, horizontal and vertical directions. The approaches started at up to 25 km distance to the plume and SO2 was measured at all times well above the detection limit. In combination with radiative transfer studies, this study indicates that an extended volcanic cloud with a concentration of 1012 molecules cm-3 at typical flight levels of 10 km can be detected unambiguously at distances of up to 80 km away. This range provides enough time (approx. 5 min) for pilots to take action to avoid entering a volcanic cloud in the flight path, suggesting that this technique can be used as an effective aid to prevent dangerous aircraft encounters with potentially ash rich volcanic clouds.

Early in-flight detection of SO2 via Differential Optical Absorption Spectroscopy: a feasible aviation safety measure to prevent potential encounters with volcanic plumes

NASA Astrophysics Data System (ADS)

Vogel, L.; Galle, B.; Kern, C.; Delgado Granados, H.; Conde, V.; Norman, P.; Arellano, S.; Landgren, O.; Lübcke, P.; Alvarez Nieves, J. M.; Cárdenas Gonzáles, L.; Platt, U.

2011-05-01

Volcanic ash constitutes a risk to aviation, mainly due to its ability to cause jet engines to fail. Other risks include the possibility of abrasion of windshields and potentially serious damage to avionic systems. These hazards have been widely recognized since the early 1980s, when volcanic ash provoked several incidents of engine failure in commercial aircraft. In addition to volcanic ash, volcanic gases also pose a threat. Prolonged and/or cumulative exposure to sulphur dioxide (SO2) or sulphuric acid (H2SO4) aerosols potentially affects e.g. windows, air frame and may cause permanent damage to engines. SO2 receives most attention among the gas species commonly found in volcanic plumes because its presence above the lower troposphere is a clear proxy for a volcanic cloud and indicates that fine ash could also be present. Up to now, remote sensing of SO2 via Differential Optical Absorption Spectroscopy (DOAS) in the ultraviolet spectral region has been used to measure volcanic clouds from ground based, airborne and satellite platforms. Attention has been given to volcanic emission strength, chemistry inside volcanic clouds and measurement procedures were adapted accordingly. Here we present a set of experimental and model results, highlighting the feasibility of DOAS to be used as an airborne early detection system of SO2 in two spatial dimensions. In order to prove our new concept, simultaneous airborne and ground-based measurements of the plume of Popocatépetl volcano, Mexico, were conducted in April 2010. The plume extended at an altitude around 5250 m above sea level and was approached and traversed at the same altitude with several forward looking DOAS systems aboard an airplane. These DOAS systems measured SO2 in the flight direction and at ± 40 mrad (2.3°) angles relative to it in both, horizontal and vertical directions. The approaches started at up to 25 km distance to the plume and SO2 was measured at all times well above the detection limit. In combination with radiative transfer studies, this study indicates that an extended volcanic cloud with a concentration of 1012 molecules cm-3 at typical flight levels of 10 km can be detected unambiguously at distances of up to 80 km away. This range provides enough time (approx. 5 min) for pilots to take action to avoid entering a volcanic cloud in the flight path, suggesting that this technique can be used as an effective aid to prevent dangerous aircraft encounters with potentially ash rich volcanic clouds.

Early in-flight detection of SO2 via Differential Optical Absorption Spectroscopy: A feasible aviation safety measure to prevent potential encounters with volcanic plumes

USGS Publications Warehouse

Vogel, L.; Galle, B.; Kern, C.; Delgado, Granados H.; Conde, V.; Norman, P.; Arellano, S.; Landgren, O.; Lubcke, P.; Alvarez, Nieves J.M.; Cardenas, Gonzales L.; Platt, U.

2011-01-01

Volcanic ash constitutes a risk to aviation, mainly due to its ability to cause jet engines to fail. Other risks include the possibility of abrasion of windshields and potentially serious damage to avionic systems. These hazards have been widely recognized 5 since the early 1980s, when volcanic ash provoked several incidents of engine failure in commercial aircraft. In addition to volcanic ash, volcanic gases also pose a threat. Prolonged and/or cumulative exposure to sulphur dioxide (SO2) or sulphuric acid (H2SO4) aerosols potentially affects e.g. windows, air frame and may cause permanent damage to engines. SO2 receives most attention among the gas species commonly found in 10 volcanic plumes because its presence above the lower troposphere is a clear proxy for a volcanic cloud and indicates that fine ash could also be present. Up to now, remote sensing of SO2 via Differential Optical Absorption Spectroscopy (DOAS) in the ultraviolet spectral region has been used to measure volcanic clouds from ground based, airborne and satellite platforms. Attention has been given to vol- 15 canic emission strength, chemistry inside volcanic clouds and measurement procedures were adapted accordingly. Here we present a set of experimental and model results, highlighting the feasibility of DOAS to be used as an airborne early detection system of SO2 in two spatial dimensions. In order to prove our new concept, simultaneous airborne and ground-based measurements of the plume of Popocatepetl volcano, Mexico, were conducted in April 2010. The plume extended at an altitude around 5250 m above sea level and was approached and traversed at the same altitude with several forward looking DOAS systems aboard an airplane. These DOAS systems measured SO2 in the flight direction and at ±40 mrad (2.3◦) angles relative to it in both, horizontal and vertical directions. The approaches started at up to 25 km distance to 25 the plume and SO2 was measured at all times well above the detection limit. In combination with radiative transfer studies, this study indicates that an extended volcanic cloud with a concentration of 1012 molecules cm−3 at typical flight levels of 10 km can be detected unambiguously at distances of up to 80 km away. This range provides enough time (approx. 5 min) for pilots to take action to avoid entering a volcanic cloud in the flight path, suggesting that this technique can be used as an effective aid to prevent dangerous aircraft encounters with potentially ash rich volcanic clouds.

Inline Monitoring of Free Water and Particulate Contamination of Jet A Fuel

DTIC Science & Technology

2015-04-10

authors expressed herein do not necessarily state or reflect those of the United States Government or the DoA, and shall not be used for advertising or...3.1 PROGENY Joel Schmitigal (TARDEC) and Mike Strong and David Beers (Progeny Systems Corporation) visited SwRI the week of 04 November 2013 to

Recombination of the steering vector of the triangle grid array in quaternions and the reduction of the MUSIC algorithm

NASA Astrophysics Data System (ADS)

Bai, Chen; Han, Dongjuan

2018-04-01

MUSIC is widely used on DOA estimation. Triangle grid is a common kind of the arrangement of array, but it is more complicated than rectangular array in calculation of steering vector. In this paper, the quaternions algorithm can reduce dimension of vector and make the calculation easier.

Evolution of Occupant Survivability Simulation Framework Using FEM-SPH Coupling

DTIC Science & Technology

2011-08-10

Conference (Oral only). • [5] K. Williams, et. al, “Validation of a Loading Model for Simulating Blast Mine Effects on Armoured Vehicles”, 7th...necessarily state or reflect those of the United States Government or the Department of the Army (DoA), and shall not be used for advertising or product endorsement purposes. 24

Waveform-Diverse Sensors

DTIC Science & Technology

2009-12-01

independent information on each individual radar pulse that is incident upon an illuminated RF tag/transponder. As such, data-rates commensurate with...Final Report Office of Naval Research Program Manager: Dr. Rabinder Madan Project Title: Waveform-Diverse Sensors Award # N00014-06-1-0004...multistatic, pulse compression, waveform diversity, DOA estimation 16. SECURITY CLASSIFICATION OF: a. REPORT b. ABSTRACT c. THIS PAGE 17. LIMITATION

Off-axis Doas Measurements At Observatoire De Haute Provence During 2001

NASA Astrophysics Data System (ADS)

Roozendael, M. Van; de Mazière, M.; Fayt, C.; Hendrick, F.; Hermans, C.

Since December 2000, a ground-based off-axis DOAS spectrometer has been operated by BIRA-IASB in the South of France at the Observatoire de Haute Provence (OHP, 44°N). The design of the instrument allows automated observations of the scattered light alternatively in the zenith direction and at 10° above the horizon (off-axis geometry). The spectrometer is polarised and follows the azimuth of the sun. Its temperature is regulated and it is equipped with a Princeton Instruments/ Hammamatsu cooled diode array detector. Observations are made every 5 minutes in the 320-390 nm range. The analysis of the spectra recorded between January and December 2001 demonstrates the sensitivity of the measurements to tropospheric contents of NO2, HCHO, O3 and BrO. Results show a large seasonality in the HCHO content with maximum values in summer. The tropospheric BrO column is found to be stable over the year in the range of approximately 1.5-2 x1013 molec/cm2, roughly consistent with GOME observations at Northern mid-latitudes. Large increases of the BrO concentration are observed in summer likely due to local pollution in the vicinity of the station.

A method for retrieving vertical ozone profiles from limb scattered measurements

NASA Astrophysics Data System (ADS)

Wang, Zijun; Chen, Shengbo; Yang, Chunyan; Jin, Lihua

2011-10-01

A two-step method is employed in this study to retrieve vertical ozone profiles using scattered measurements from the limb of the atmosphere. The combination of the Differential Optical Absorption Spectroscopy (DOAS) and the Multiplicative Algebraic Reconstruction Technique (MART) is proposed. First, the limb radiance, measured over a range of tangent heights, is processed using the DOAS technique to recover the effective column densities of atmospheric ozone. Second, these effective column densities along the lines of sight (LOSs) are inverted using the MART coupled with a forward model SCIATRAN (radiative transfer model for SCIAMACHY) to derive the ozone profiles. This method is applied to Optical Spectrograph and Infra Red Imager System (OSIRIS) radiance, using the wavelength windows 571-617 nm. Vertical ozone profiles between 10 and 48 km are derived with a vertical resolution of 1 km. The results illustrate a good agreement with the cloud-free coincident SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) ozone measurements, with deviations less than ±10% (±5% for altitudes from 17 to 47 km). Furthermore, sensitivities of retrieved ozone to aerosol, cloud parameters and NO2 concentration are also investigated.

Computer-aided discovery of biological activity spectra for anti-aging and anti-cancer olive oil oleuropeins.

PubMed

Corominas-Faja, Bruna; Santangelo, Elvira; Cuyàs, Elisabet; Micol, Vicente; Joven, Jorge; Ariza, Xavier; Segura-Carretero, Antonio; García, Jordi; Menendez, Javier A

2014-09-01

Aging is associated with common conditions, including cancer, diabetes, cardiovascular disease, and Alzheimer's disease. The type of multi-targeted pharmacological approach necessary to address a complex multifaceted disease such as aging might take advantage of pleiotropic natural polyphenols affecting a wide variety of biological processes. We have recently postulated that the secoiridoids oleuropein aglycone (OA) and decarboxymethyl oleuropein aglycone (DOA), two complex polyphenols present in health-promoting extra virgin olive oil (EVOO), might constitute a new family of plant-produced gerosuppressant agents. This paper describes an analysis of the biological activity spectra (BAS) of OA and DOA using PASS (Prediction of Activity Spectra for Substances) software. PASS can predict thousands of biological activities, as the BAS of a compound is an intrinsic property that is largely dependent on the compound's structure and reflects pharmacological effects, physiological and biochemical mechanisms of action, and specific toxicities. Using Pharmaexpert, a tool that analyzes the PASS-predicted BAS of substances based on thousands of "mechanism-effect" and "effect-mechanism" relationships, we illuminate hypothesis-generating pharmacological effects, mechanisms of action, and targets that might underlie the anti-aging/anti-cancer activities of the gerosuppressant EVOO oleuropeins.

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-12-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of atmospheric remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and comma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at 0.5 nm resolution, suitable for a number of typical DOAS applications.

NO2 DOAS measurements from ground and space: comparison of ground based measurements and OMI data in Mexico City

NASA Astrophysics Data System (ADS)

Rivera, C.; Stremme, W.; Grutter, M.

2012-04-01

The combination of satellite data and ground based measurements can provide valuable information about atmospheric chemistry and air quality. In this work we present a comparison between measured ground based NO2 differential columns at the Universidad Nacional Autónoma de México (UNAM) in Mexico City, using the Differential Optical Absorption Spectroscopy (DOAS) technique and NO2 total columns measured by the Ozone Monitoring Instrument (OMI) onboard the Aura satellite using the same measurement technique. From these data, distribution maps of average NO2 above the Mexico basin were constructed and hot spots inside the city could be identified. In addition, a clear footprint was detected from the Tula industrial area, ~50 km northwest of Mexico City, where a refinery, a power plant and other industries are located. A less defined footprint was identified in the Cuernavaca basin, South of Mexico City, and the nearby cities of Toluca and Puebla do not present strong enhancements in the NO2 total columns. With this study we expect to cross-validate space and ground measurements and provide useful information for future studies.

Detection of Ozone and Nitric Oxide in Decomposition Products of Air-Insulated Switchgear Using Ultraviolet Differential Optical Absorption Spectroscopy (UV-DOAS).

PubMed

Li, Yalong; Zhang, Xiaoxing; Li, Xin; Cui, Zhaolun; Xiao, Hai

2018-01-01

Air-insulated switchgear cabinets play a role in the protection and control of the modern power grid, and partial discharge (PD) switchgear is a long-term process in the non-normal operation of one of the situations; thus, condition monitoring of the switchgear is important. The air-insulated switchgear during PD enables the decomposition of air components, namely, O 3 and NO. A set of experimental platforms was designed on the basis of the principle of ultraviolet differential optical absorption spectroscopy (UV-DOAS) to detect O 3 and NO concentrations in air-insulated switchgear. Differential absorption algorithm and wavelet transform were used to extract effective absorption spectra; a linear relationship between O 3 and NO concentrations and absorption spectrum data were established. O 3 detection linearity was up to 0.9992 and the detection limit was at 3.76 ppm. NO detection linearity was up to 0.9990 and the detection limit was at 0.64 ppm. Results indicate that detection platform is suitable for detecting trace O 3 and NO gases produced by PD of the air-insulated switchgear.

Characterization and analysis of diesel exhaust odor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shala, F.J.

1983-01-01

An instrumental method known as the Diesel Odor Analysis System or DOAS, has been developed at A.D. Little, Inc. for measuring diesel exhaust odor. It was of interest to determine which compound or compounds in the oxygenated fraction of the exhaust were primarily responsible for the odor correlation as developed at A.D. Little, Inc. This was accomplished by observing how the measurement of the exhaust odor intensity and number of chemical constituents of the oxygenate fraction were changing with respect to the odor values as measured by the DOAS. Benzaldehyde was found to give the best correlation (R = 0.98)more » with odor. A quantitative relationship between exhaust odor as measured by the total intensity of aroma (TIA) and the benzaldehyde concentration (B) in ppm in the exhaust is given by: TIA = 1.11 log/sub 10/(B) + 4.10. This correlation was supported by results obtained from two other diesel engine exhaust sources. A methyl benzaldehyde isomer also yielded a good correlation (R = 0.90) with odor. Air to fuel ratio correlations were determined for the tentatively identified compounds, cinnamaldehyde (R = 0.94) and a C2-benzaldehyde isomer (R = 0.94).« less

Estimator banks: a new tool for direction-of-arrival estimation

NASA Astrophysics Data System (ADS)

Gershman, Alex B.; Boehme, Johann F.

1997-10-01

A new powerful tool for improving the threshold performance of direction-of-arrival (DOA) estimation is considered. The essence of our approach is to reduce the number of outliers in the threshold domain using the so-called estimator bank containing multiple 'parallel' underlying DOA estimators which are based on pseudorandom resampling of the MUSIC spatial spectrum for given data batch or sample covariance matrix. To improve the threshold performance relative to conventional MUSIC, evolutionary principles are used, i.e., only 'successful' underlying estimators (having no failure in the preliminary estimated source localization sectors) are exploited in the final estimate. An efficient beamspace root implementation of the estimator bank approach is developed, combined with the array interpolation technique which enables the application to arbitrary arrays. A higher-order extension of our approach is also presented, where the cumulant-based MUSIC estimator is exploited as a basic technique for spatial spectrum resampling. Simulations and experimental data processing show that our algorithm performs well below the MUSIC threshold, namely, has the threshold performance similar to that of the stochastic ML method. At the same time, the computational cost of our algorithm is much lower than that of stochastic ML because no multidimensional optimization is involved.

A Unitary ESPRIT Scheme of Joint Angle Estimation for MOTS MIMO Radar

PubMed Central

Wen, Chao; Shi, Guangming

2014-01-01

The transmit array of multi-overlapped-transmit-subarray configured bistatic multiple-input multiple-output (MOTS MIMO) radar is partitioned into a number of overlapped subarrays, which is different from the traditional bistatic MIMO radar. In this paper, a new unitary ESPRIT scheme for joint estimation of the direction of departure (DOD) and the direction of arrival (DOA) for MOTS MIMO radar is proposed. In our method, each overlapped-transmit-subarray (OTS) with the identical effective aperture is regarded as a transmit element and the characteristics that the phase delays between the two OTSs is utilized. First, the measurements corresponding to all the OTSs are partitioned into two groups which have a rotational invariance relationship with each other. Then, the properties of centro-Hermitian matrices and real-valued rotational invariance factors are exploited to double the measurement samples and reduce computational complexity. Finally, the close-formed solution of automatically paired DOAs and DODs of targets is derived in a new manner. The proposed scheme provides increased estimation accuracy with the combination of inherent advantages of MOTS MIMO radar with unitary ESPRIT. Simulation results are presented to demonstrate the effectiveness and advantage of the proposed scheme. PMID:25106023

A unitary ESPRIT scheme of joint angle estimation for MOTS MIMO radar.

PubMed

Wen, Chao; Shi, Guangming

2014-08-07

The transmit array of multi-overlapped-transmit-subarray configured bistatic multiple-input multiple-output (MOTS MIMO) radar is partitioned into a number of overlapped subarrays, which is different from the traditional bistatic MIMO radar. In this paper, a new unitary ESPRIT scheme for joint estimation of the direction of departure (DOD) and the direction of arrival (DOA) for MOTS MIMO radar is proposed. In our method, each overlapped-transmit-subarray (OTS) with the identical effective aperture is regarded as a transmit element and the characteristics that the phase delays between the two OTSs is utilized. First, the measurements corresponding to all the OTSs are partitioned into two groups which have a rotational invariance relationship with each other. Then, the properties of centro-Hermitian matrices and real-valued rotational invariance factors are exploited to double the measurement samples and reduce computational complexity. Finally, the close-formed solution of automatically paired DOAs and DODs of targets is derived in a new manner. The proposed scheme provides increased estimation accuracy with the combination of inherent advantages of MOTS MIMO radar with unitary ESPRIT. Simulation results are presented to demonstrate the effectiveness and advantage of the proposed scheme.

Nonlinear Blind Compensation for Array Signal Processing Application

PubMed Central

Ma, Hong; Jin, Jiang; Zhang, Hua

2018-01-01

Recently, nonlinear blind compensation technique has attracted growing attention in array signal processing application. However, due to the nonlinear distortion stemming from array receiver which consists of multi-channel radio frequency (RF) front-ends, it is too difficult to estimate the parameters of array signal accurately. A novel nonlinear blind compensation algorithm aims at the nonlinearity mitigation of array receiver and its spurious-free dynamic range (SFDR) improvement, which will be more precise to estimate the parameters of target signals such as their two-dimensional directions of arrival (2-D DOAs). Herein, the suggested method is designed as follows: the nonlinear model parameters of any channel of RF front-end are extracted to synchronously compensate the nonlinear distortion of the entire receiver. Furthermore, a verification experiment on the array signal from a uniform circular array (UCA) is adopted to testify the validity of our approach. The real-world experimental results show that the SFDR of the receiver is enhanced, leading to a significant improvement of the 2-D DOAs estimation performance for weak target signals. And these results demonstrate that our nonlinear blind compensation algorithm is effective to estimate the parameters of weak array signal in concomitance with strong jammers. PMID:29690571

Real-time vehicle noise cancellation techniques for gunshot acoustics

NASA Astrophysics Data System (ADS)

Ramos, Antonio L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald

2012-06-01

Acoustical sniper positioning systems rely on the detection and direction-of-arrival (DOA) estimation of the shockwave and the muzzle blast in order to provide an estimate of a potential snipers location. Field tests have shown that detecting and estimating the DOA of the muzzle blast is a rather difficult task in the presence of background noise sources, e.g., vehicle noise, especially in long range detection and absorbing terrains. In our previous work presented in the 2011 edition of this conference we highlight the importance of improving the SNR of the gunshot signals prior to the detection and recognition stages, aiming at lowering the false alarm and miss-detection rates and, thereby, increasing the reliability of the system. This paper reports on real-time noise cancellation techniques, like Spectral Subtraction and Adaptive Filtering, applied to gunshot signals. Our model assumes the background noise as being short-time stationary and uncorrelated to the impulsive gunshot signals. In practice, relatively long periods without signal occur and can be used to estimate the noise spectrum and its first and second order statistics as required in the spectral subtraction and adaptive filtering techniques, respectively. The results presented in this work are supported with extensive simulations based on real data.

Comparison of ASTM D613 and ASTM D6890

DTIC Science & Technology

2016-04-01

product , process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement...state or reflect those of the United States Government or the DoA, and shall not be used for advertising or product endorsement purposes...methylnaphthalene proved to be an impractical material for reference values. The ASTM Diesel National Exchange Group ran a study and determined that

Source Localization in Wireless Sensor Networks with Randomly Distributed Elements under Multipath Propagation Conditions

DTIC Science & Technology

2009-03-01

IN WIRELESS SENSOR NETWORKS WITH RANDOMLY DISTRIBUTED ELEMENTS UNDER MULTIPATH PROPAGATION CONDITIONS by Georgios Tsivgoulis March 2009...COVERED Engineer’s Thesis 4. TITLE Source Localization in Wireless Sensor Networks with Randomly Distributed Elements under Multipath Propagation...the non-line-of-sight information. 15. NUMBER OF PAGES 111 14. SUBJECT TERMS Wireless Sensor Network , Direction of Arrival, DOA, Random

Synthesis, structural characterization and mobility measurement of electron accepting pyrazine derivatives

NASA Astrophysics Data System (ADS)

Lai, William W.

Several pyrazine based cyano aza derivatives have been synthesized and electronic devices made from them. Hole and electron mobilities were measured using a time of flight (TOF) method with silicon wafers as both the substrate and charge carrier generation layer. The high density of charge carriers generated from silicon allowed for film layers as thin as 100nm and up to 250nm. Two compounds, 2,3,6,7-tetracyano-1,4,5,8-tetraazanapthalene (TCNN) and 2,3,6,7-tetracyano-9,10-dioctyl-1,4,5,6,9,10-hexaazaanthracene (DOA) were shown to be good electron acceptors. The potentials at which TCNN and DOA are reduced was -0.03 and -1.5 volts respectively. Electron mobilities of both compounds were found to be 2x10-5 cm2V˙s . The previously unreported oxidation potential of 2,3,6,7-tetracyano-9,10-dioctyl 1,4,5,6,9,10-hexaazaanthracene was measured and the hole mobility was determined to be 2x10-5 cm2V˙s . In the case of DOA, the charge carrier density of the electron carriers was comparable to that of the charge carrier density of the hole carriers. In contrast, the electron TOF signal of TCNN, which does not exhibit an oxidation, is greater than the hole TOF signal by roughly 200 fold. The inability for TCNN to act as a hole carrier was remedied by combining it with tetrathiafulvalene (TTF) as an electron donor. Crystals of the 1:1 complex were grown and the solved structure revealed segregated stacking. Conductivity measurements, by both two and four point methods determined the range of conductivity ranging from 10-5 to 10-6 Scm . The electron and hole mobility of the material was determined to be 2x10-5 and 2x10-6 cm2V˙s respectively. With the complementary TTF:TCNN system, the electron V-s and hole TOF signals were comparable, indicating a material that can equally conduct electrons or holes.

The Small Whiskbroom Imager for atmospheric compositioN monitorinG (SWING) and its operations from an unmanned aerial vehicle (UAV) during the AROMAT campaign

NASA Astrophysics Data System (ADS)

Merlaud, Alexis; Tack, Frederik; Constantin, Daniel; Georgescu, Lucian; Maes, Jeroen; Fayt, Caroline; Mingireanu, Florin; Schuettemeyer, Dirk; Meier, Andreas Carlos; Schönardt, Anja; Ruhtz, Thomas; Bellegante, Livio; Nicolae, Doina; Den Hoed, Mirjam; Allaart, Marc; Van Roozendael, Michel

2018-01-01

The Small Whiskbroom Imager for atmospheric compositioN monitorinG (SWING) is a compact remote sensing instrument dedicated to mapping trace gases from an unmanned aerial vehicle (UAV). SWING is based on a compact visible spectrometer and a scanning mirror to collect scattered sunlight. Its weight, size, and power consumption are respectively 920 g, 27 cm × 12 cm × 8 cm, and 6 W. SWING was developed in parallel with a 2.5 m flying-wing UAV. This unmanned aircraft is electrically powered, has a typical airspeed of 100 km h-1, and can operate at a maximum altitude of 3 km. We present SWING-UAV experiments performed in Romania on 11 September 2014 during the Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaign, which was dedicated to test newly developed instruments in the context of air quality satellite validation. The UAV was operated up to 700 m above ground, in the vicinity of the large power plant of Turceni (44.67° N, 23.41° E; 116 m a. s. l. ). These SWING-UAV flights were coincident with another airborne experiment using the Airborne imaging differential optical absorption spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP), and with ground-based DOAS, lidar, and balloon-borne in situ observations. The spectra recorded during the SWING-UAV flights are analysed with the DOAS technique. This analysis reveals NO2 differential slant column densities (DSCDs) up to 13±0.6×1016 molec cm-2. These NO2 DSCDs are converted to vertical column densities (VCDs) by estimating air mass factors. The resulting NO2 VCDs are up to 4.7±0.4×1016 molec cm-2. The water vapour DSCD measurements, up to 8±0.15×1022 molec cm-2, are used to estimate a volume mixing ratio of water vapour in the boundary layer of 0.013±0.002 mol mol-1. These geophysical quantities are validated with the coincident measurements.

The Cabauw Intercomparison Campaign for Nitrogen Dioxide Measuring Instruments (CINDI): Design, Execution, and Early Results

NASA Technical Reports Server (NTRS)

Piters, Ankie; Boersma, K.F.; Kroon, M.; Hains, J. C.; Roozendael, M. Van; Wittrock, F.; Abuhassan, N.; Adams, C.; Akrami, M.; Allaart, M. A. F.;

Ship-based MAX-DOAS measurements of tropospheric NO2, SO2, and HCHO distribution along the Yangtze River

NASA Astrophysics Data System (ADS)

Hong, Qianqian; Liu, Cheng; Chan, Ka Lok; Hu, Qihou; Xie, Zhouqing; Liu, Haoran; Si, Fuqi; Liu, Jianguo

2018-04-01

In this paper, we present ship-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements of tropospheric trace gases' distribution along the Yangtze River during winter 2015. The measurements were performed along the Yangtze River between Shanghai and Wuhan, covering major industrial areas in eastern China. Tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) were retrieved using the air mass factor calculated by the radiative transfer model. Enhanced tropospheric NO2 and SO2 VCDs were detected over downwind areas of industrial zones over the Yangtze River. In addition, spatial distributions of atmospheric pollutants are strongly affected by meteorological conditions; i.e., positive correlations were found between concentration of pollutants and wind speed over these areas, indicating strong influence of transportation of pollutants from high-emission upwind areas along the Yangtze River. Comparison of tropospheric NO2 VCDs between ship-based MAX-DOAS and Ozone Monitoring Instrument (OMI) satellite observations shows good agreement with each other, with a Pearson correlation coefficient (R) of 0.82. In this study, the NO2 / SO2 ratio was used to estimate the relative contributions of industrial sources and vehicle emissions to ambient NO2 levels. Analysis results of the NO2 / SO2 ratio show a higher contribution of industrial NO2 emissions in Jiangsu Province, while NO2 levels in Jiangxi and Hubei provinces are mainly related to vehicle emissions. These results indicate that different pollution control strategies should be applied in different provinces. In addition, multiple linear regression analysis of ambient carbon monoxide (CO) and odd oxygen (Ox) indicated that the primary emission and secondary formation of HCHO contribute 54.4 ± 3.7 % and 39.3 ± 4.3 % to the ambient HCHO, respectively. The largest contribution from primary emissions in winter suggested that photochemically induced secondary formation of HCHO is reduced due to lower solar irradiance in winter. Our findings provide an improved understanding of major pollution sources along the eastern part of the Yangtze River which are useful for designing specific air pollution control policies.

Direction of Arrival Studies of Medium Frequency Burst Radio Emissions at Toolik Lake, AK

NASA Astrophysics Data System (ADS)

Bunch, N.; Labelle, J.; Weatherwax, A.; Lummerzheim, D.; Stenbaek-Nielsen, H.

2008-05-01

MF burst is an impulsive radio emission of auroral origin, which can be detected by ground-based instruments at frequencies between 1,300 and 4,500kHz. MF burst has been shown to be associated with substorm onset, but its exact generation mechanism remains unknown, although it is thought to arise from mode conversion radiation [see review by LaBelle and Treumann, 2002] . In search of the generation mechanism of this emission, Dartmouth College has deployed radio interferometers in Alaska, Northern Canada, Greenland, and Antarctica, including a three-element interferometer deployed to Toolik Field Station in Alaska during the summer of 2006. This instrument measured spectra, amplitudes and directions of arrival (DOA's) of over 47 MF burst events between November 30, 2006 and May 26, 2007. These data represent the first DOA measurements of impulsive MF burst, of which selected case studies were presented at the Fall 2007 AGU conference. Here we present a statistical survey of all 47 events as well as detailed analysis of three events occurring on: Mar 5, Mar 23, and Nov 20, 2007. For the statistical survey, we present distributions of DOA as a function of local time and frequency. In each case study we analyze the direction of arrival of the emissions as a function of both time and frequency within each event. The time variations will be compared with the time variations of optical auroral forms simultaneously measured with all-sky cameras. The dependence of the arrival direction on frequency enables a significant test of the generation mechanism whereby the waves are emitted at the local plasma or upper hybrid frequency in the topside ionosphere, predicting that higher frequencies should originate at lower altitudes. These three events have been selected because All-Sky camera data are available at these times from Toolik Lake and Fort Yukon, Alaska. These are critical both for identifying which optical features are associated with the radio emissions as well as for constraining the electron density profiles used for ray tracing. Ray tracing is a critical tool for this study, and several alternative models will be used in order to understand the uncertainty in these events.

Retrieval of aerosol optical and micro-physical properties with 2D-MAX-DOAS

NASA Astrophysics Data System (ADS)

Ortega, Ivan; Coburn, Sean; Hostetler, Chris; Ferrare, Rich; Hair, Johnathan; Kassianov, Evgueni; Barnard, James; Berg, Larry; Schmid, Beat; Tomlinson, Jason; Hodges, Gary; Lantz, Kathy; Wagner, Thomas; Volkamer, Rainer

2015-04-01

Recent retrievals of 2 dimensional (2D) Multi-AXis Differential Optical Absorption Spectroscopy (2D-MAX-DOAS) have highlighted its importance in order to infer diurnal horizontal in-homogeneities around the measurement site. In this work, we expand the capabilities of 2D measurements in order to estimate simultaneously aerosol optical and micro-physical properties. Specifically, we present a retrieval method to obtain: (1) aerosol optical thickness (AOT) in the boundary layer (BL) and free troposphere (FT) and (2) the effective complex refractive index and the effective radius of the aerosol column size distribution. The retrieval method to obtain AOT is based on an iterative comparison of measured normalized radiances, oxygen collision pair (O4), and absolute Raman Scattering Probability (RSP) with the forward model calculations derived with the radiative transfer model McArtim based on defined aerosol extinction profiles. Once the aerosol load is determined we use multiple scattering phase functions and single scattering albedo (SSA) obtained with Mie calculations which then constrain the RTM to forward model solar almucantar normalized radiances. The simulated almucantar normalized radiances are then compared to the measured normalized radiances. The best-fit, determined by minimizing the root mean square, retrieves the complex refractive index, and effective radius. We apply the retrieval approach described above to measurements carried out during the 2012 intensive operation period of the Two Column Aerosol Project (TCAP) held on Cape Cod, MA, USA. Results are presented for two ideal case studies with both large and small aerosol loading and similar air mass outflow from the northeast coast of the US over the West Atlantic Ocean. The aerosol optical properties are compared with several independent instruments, including the NASA Langley airborne High Spectral Resolution Lidar (HSRL-2) for highly resolved extinction profiles during the overpasses, and with the co-located Multi Filter Rotating Shadow band Radiometer (MFRSR), and the Cimel Sun photometer for aerosol load at several wavelengths. To test aerosol horizontal homogeneity we use quantitatively analysis of asymmetry of solar azimuth normalized radiances and RSP. The aerosol column microphysical properties will be compared with merged size distribution of several in-situ instruments from airborne measurements during overpasses of the DoE-G1 aircraft around the ground measurement site.

Biomarker Discovery in Gulf War Veterans: Development of a War Illness Diagnostic Panel

DTIC Science & Technology

2015-10-01

reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of...subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO...a relatively low cost. This interdisciplinary research study is led by a team of experienced GWI investigators and statisticians at Baylor

Development of Parallel Architectures for Sensor Array Processing. Volume 1

DTIC Science & Technology

1993-08-01

required for the DOA estimation [ 1-7]. The Multiple Signal Classification ( MUSIC ) [ 1] and the Estimation of Signal Parameters by Rotational...manifold and the estimated subspace. Although MUSIC is a high resolution algorithm, it has several drawbacks including the fact that complete knowledge of...thoroughly, MUSIC algorithm was selected to develop special purpose hardware for real time computation. Summary of the MUSIC algorithm is as follows

Medical Services: Medical Record Administration and Health Care Documentation

DTIC Science & Technology

1999-05-03

prepared for each patient who must have one. (5) Ensure that a blood sample for deoxyribonucleic acid ( DNA ) identification is on file with the DNA ...degenerative joint disease DM diabetes mellitus DNA deoxyribonucleic acid DNR do not resuscitate DO Doctor of Osteopathy DOA dead on arrival DOB date...vein thrombosis DWI driving while intoxicated Dx diagnosis EBL estimated blood loss EBV Epstein-Barr virus ECG; EKG electrocardiogram E. coli

Multimillion Atom Reactive Simulations of Nanostructured Energetic Materials

DTIC Science & Technology

2007-08-01

code) 2007 Reprint Aug 2006-Aug 2007 Multimillion Atom Reactive Simulations of Nanostructured Energetic Materials W911NF-04-1-0178 sub 2781-USC-DOA...Priya Vashishta 213 821 2663 Reset Multimillion Atom Reactive Simulations of Nanostructured Energetic Materials Priya Vashishta,∗ Rajiv K. Kalia...function of the particle velocity that drives the shock [18]. The MD and experimental data agree very well. Furthermore, the simulation shows a sudden

Evidence for nonallopatric speciation among closely related sympatric Heliotropium species in the Atacama Desert

PubMed Central

Luebert, Federico; Jacobs, Pit; Hilger, Hartmut H; Muller, Ludo A H

2014-01-01

The genetic structure of populations of closely related, sympatric species may hold the signature of the geographical mode of the speciation process. In fully allopatric speciation, it is expected that genetic differentiation between species is homogeneously distributed across the genome. In nonallopatric speciation, the genomes may remain undifferentiated to a large extent. In this article, we analyzed the genetic structure of five sympatric species from the plant genus Heliotropium in the Atacama Desert. We used amplified fragment length polymorphisms (AFLPs) to characterize the genetic structure of these species and evaluate their genetic differentiation as well as the number of loci subject to positive selection using divergence outlier analysis (DOA). The five species form distinguishable groups in the genetic space, with zones of overlap, indicating that they are possibly not completely isolated. Among-species differentiation accounts for 35% of the total genetic differentiation (FST = 0.35), and FST between species pairs is positively correlated with phylogenetic distance. DOA suggests that few loci are subject to positive selection, which is in line with a scenario of nonallopatric speciation. These results support the idea that sympatric species of Heliotropium sect. Cochranea are under an ongoing speciation process, characterized by a fluctuation of population ranges in response to pulses of arid and humid periods during Quaternary times. PMID:24558582

Evidence for nonallopatric speciation among closely related sympatric Heliotropium species in the Atacama Desert.

PubMed

Luebert, Federico; Jacobs, Pit; Hilger, Hartmut H; Muller, Ludo A H

2014-02-01

The genetic structure of populations of closely related, sympatric species may hold the signature of the geographical mode of the speciation process. In fully allopatric speciation, it is expected that genetic differentiation between species is homogeneously distributed across the genome. In nonallopatric speciation, the genomes may remain undifferentiated to a large extent. In this article, we analyzed the genetic structure of five sympatric species from the plant genus Heliotropium in the Atacama Desert. We used amplified fragment length polymorphisms (AFLPs) to characterize the genetic structure of these species and evaluate their genetic differentiation as well as the number of loci subject to positive selection using divergence outlier analysis (DOA). The five species form distinguishable groups in the genetic space, with zones of overlap, indicating that they are possibly not completely isolated. Among-species differentiation accounts for 35% of the total genetic differentiation (F ST = 0.35), and F ST between species pairs is positively correlated with phylogenetic distance. DOA suggests that few loci are subject to positive selection, which is in line with a scenario of nonallopatric speciation. These results support the idea that sympatric species of Heliotropium sect. Cochranea are under an ongoing speciation process, characterized by a fluctuation of population ranges in response to pulses of arid and humid periods during Quaternary times.

Sparse Method for Direction of Arrival Estimation Using Denoised Fourth-Order Cumulants Vector.

PubMed

Fan, Yangyu; Wang, Jianshu; Du, Rui; Lv, Guoyun

2018-06-04

Fourth-order cumulants (FOCs) vector-based direction of arrival (DOA) estimation methods of non-Gaussian sources may suffer from poor performance for limited snapshots or difficulty in setting parameters. In this paper, a novel FOCs vector-based sparse DOA estimation method is proposed. Firstly, by utilizing the concept of a fourth-order difference co-array (FODCA), an advanced FOCs vector denoising or dimension reduction procedure is presented for arbitrary array geometries. Then, a novel single measurement vector (SMV) model is established by the denoised FOCs vector, and efficiently solved by an off-grid sparse Bayesian inference (OGSBI) method. The estimation errors of FOCs are integrated in the SMV model, and are approximately estimated in a simple way. A necessary condition regarding the number of identifiable sources of our method is presented that, in order to uniquely identify all sources, the number of sources K must fulfill K ≤ ( M 4 - 2 M 3 + 7 M 2 - 6 M ) / 8 . The proposed method suits any geometry, does not need prior knowledge of the number of sources, is insensitive to associated parameters, and has maximum identifiability O ( M 4 ) , where M is the number of sensors in the array. Numerical simulations illustrate the superior performance of the proposed method.

Miniaturized differential optical absorption spectroscopy (DOAS) system for the analysis of NO2

NASA Astrophysics Data System (ADS)

Morales, J. Alberto; Walsh, James E.; Treacy, Jack E.; Garland, Wendy E.

2003-03-01

Current trends in optical design engineering are leading to the development of new systems which can analyze atmospheric pollutants in a fast and easy way, allowing remote-sensing and miniaturization at a low cost. A small portable fiber-optic based system is presented for the spectroscopic analysis of a common gas pollutant, NO2. The novel optical set-up described consists of a small telescope that collects ultraviolet-visible light from a xenon lamp located 600 m away. The light is coupled into a portable diode array spectrometer through a fiber-optic cable and the system is controlled by a lap-top computer where the spectra are recorded. Using the spectrum of the lamp as a reference, the absorption spectrum of the open path between the lamp and the telescope is calculated. Known absorption features in the NO2 spectrum are used to calculate the concentration of the pollutant using the principles of Differential Optical Absorption Spectroscopy (DOAS). Calibration is carried by using sample gas bags of known concentration of the pollutant. The results obtained demonstrate that it is possible to detect and determine NO2 concentrations directly from the atmosphere at typical environment levels by using an inexpensive field based fiber-optic spectrometer system.

No-search algorithm for direction of arrival estimation

NASA Astrophysics Data System (ADS)

Tuncer, T. Engin; Ã-Zgen, M. Tankut

2009-10-01

Direction of arrival estimation (DOA) is an important problem in ionospheric research and electromagnetics as well as many other fields. When superresolution techniques are used, a computationally expensive search should be performed in general. In this paper, a no-search algorithm is presented. The idea is to separate the source signals in the time-frequency plane by using the Short-Time Fourier Transform. The direction vector for each source is found by coherent summation over the instantaneous frequency (IF) tracks of the individual sources which are found automatically by employing morphological image processing. Both overlapping and nonoverlapping source IF tracks can be processed and identified by the proposed approach. The CLEAN algorithm is adopted in order to isolate the IF tracks of the overlapping sources with different powers. The proposed method is very effective in finding the IF tracks and can be applied for signals with arbitrary IF characteristics. While the proposed method can be applied to any sensor geometry, planar uniform circular arrays (UCA) bring additional advantages. Different properties of the UCA are presented, and it is shown that the DOA angles can be found as the mean-square error optimum solution of a linear matrix equation. Several simulations are done, and it is shown that the proposed approach performs significantly better than the conventional methods.

CYBERWAR-2012/13: Siegel 2011 Predicted Cyberwar Via ACHILLES-HEEL DIGITS BEQS BEC ZERO-DIGIT BEC of/in ACHILLES-HEEL DIGITS Log-Law Algebraic-Inversion to ONLY BEQS BEC Digit-Physics U Barabasi Network/Graph-Physics BEQS BEC JAMMING Denial-of-Access(DOA) Attacks 2012-Instantiations

NASA Astrophysics Data System (ADS)

Huffmann, Master; Siegel, Edward Carl-Ludwig

2013-03-01

Newcomb-Benford(NeWBe)-Siegel log-law BEC Digit-Physics Network/Graph-Physics Barabasi et.al. evolving-``complex''-networks/graphs BEC JAMMING DOA attacks: Amazon(weekends: Microsoft I.E.-7/8(vs. Firefox): Memorial-day, Labor-day,...), MANY U.S.-Banks:WF,BoA,UB,UBS,...instantiations AGAIN militate for MANDATORY CONVERSION to PARALLEL ANALOG FAULT-TOLERANT but slow(er) SECURITY-ASSURANCE networks/graphs in parallel with faster ``sexy'' DIGITAL-Networks/graphs:``Cloud'', telecomm: n-G,..., because of common ACHILLES-HEEL VULNERABILITY: DIGITS!!! ``In fast-hare versus slow-tortoise race, Slow-But-Steady ALWAYS WINS!!!'' (Zeno). {Euler [#s(1732)] ∑- ∏()-Riemann[Monats. Akad. Berlin (1859)] ∑- ∏()- Kummer-Bernoulli (#s)}-Newcomb [Am.J.Math.4(1),39 (81) discovery of the QUANTUM!!!]-{Planck (01)]}-{Einstein (05)]-Poincar e [Calcul Probabilités,313(12)]-Weyl[Goett. Nach.(14); Math.Ann.77,313(16)]-(Bose (24)-Einstein(25)]-VS. -Fermi (27)-Dirac(27))-Menger [Dimensiontheorie(29)]-Benford [J.Am. Phil.Soc.78,115(38)]-Kac[Maths Stats.-Reason. (55)]- Raimi [Sci.Am.221,109(69)]-Jech-Hill [Proc.AMS,123,3,887(95)] log-function

Off-Grid Direction of Arrival Estimation Based on Joint Spatial Sparsity for Distributed Sparse Linear Arrays

PubMed Central

Liang, Yujie; Ying, Rendong; Lu, Zhenqi; Liu, Peilin

2014-01-01

In the design phase of sensor arrays during array signal processing, the estimation performance and system cost are largely determined by array aperture size. In this article, we address the problem of joint direction-of-arrival (DOA) estimation with distributed sparse linear arrays (SLAs) and propose an off-grid synchronous approach based on distributed compressed sensing to obtain larger array aperture. We focus on the complex source distribution in the practical applications and classify the sources into common and innovation parts according to whether a signal of source can impinge on all the SLAs or a specific one. For each SLA, we construct a corresponding virtual uniform linear array (ULA) to create the relationship of random linear map between the signals respectively observed by these two arrays. The signal ensembles including the common/innovation sources for different SLAs are abstracted as a joint spatial sparsity model. And we use the minimization of concatenated atomic norm via semidefinite programming to solve the problem of joint DOA estimation. Joint calculation of the signals observed by all the SLAs exploits their redundancy caused by the common sources and decreases the requirement of array size. The numerical results illustrate the advantages of the proposed approach. PMID:25420150

Localization and separation of acoustic sources by using a 2.5-dimensional circular microphone array.

PubMed

Bai, Mingsian R; Lai, Chang-Sheng; Wu, Po-Chen

2017-07-01

Circular microphone arrays (CMAs) are sufficient in many immersive audio applications because azimuthal angles of sources are considered more important than the elevation angles in those occasions. However, the fact that CMAs do not resolve the elevation angle well can be a limitation for some applications which involves three-dimensional sound images. This paper proposes a 2.5-dimensional (2.5-D) CMA comprised of a CMA and a vertical logarithmic-spacing linear array (LLA) on the top. In the localization stage, two delay-and-sum beamformers are applied to the CMA and the LLA, respectively. The direction of arrival (DOA) is estimated from the product of two array output signals. In the separation stage, Tikhonov regularization and convex optimization are employed to extract the source amplitudes on the basis of the estimated DOA. The extracted signals from two arrays are further processed by the normalized least-mean-square algorithm with the internal iteration to yield the source signal with improved quality. To validate the 2.5-D CMA experimentally, a three-dimensionally printed circular array comprised of a 24-element CMA and an eight-element LLA is constructed. Objective perceptual evaluation of speech quality test and a subjective listening test are also undertaken.

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-08-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer for atmospheric research has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications particularly from space (LEO, GEO orbits) and from HAPs or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at better than 0.5 nm resolution, suitable for a number of typical DOAS applications.

Computational Depth of Anesthesia via Multiple Vital Signs Based on Artificial Neural Networks.

PubMed

Sadrawi, Muammar; Fan, Shou-Zen; Abbod, Maysam F; Jen, Kuo-Kuang; Shieh, Jiann-Shing

2015-01-01

This study evaluated the depth of anesthesia (DoA) index using artificial neural networks (ANN) which is performed as the modeling technique. Totally 63-patient data is addressed, for both modeling and testing of 17 and 46 patients, respectively. The empirical mode decomposition (EMD) is utilized to purify between the electroencephalography (EEG) signal and the noise. The filtered EEG signal is subsequently extracted to achieve a sample entropy index by every 5-second signal. Then, it is combined with other mean values of vital signs, that is, electromyography (EMG), heart rate (HR), pulse, systolic blood pressure (SBP), diastolic blood pressure (DBP), and signal quality index (SQI) to evaluate the DoA index as the input. The 5 doctor scores are averaged to obtain an output index. The mean absolute error (MAE) is utilized as the performance evaluation. 10-fold cross-validation is performed in order to generalize the model. The ANN model is compared with the bispectral index (BIS). The results show that the ANN is able to produce lower MAE than BIS. For the correlation coefficient, ANN also has higher value than BIS tested on the 46-patient testing data. Sensitivity analysis and cross-validation method are applied in advance. The results state that EMG has the most effecting parameter, significantly.

Computational Depth of Anesthesia via Multiple Vital Signs Based on Artificial Neural Networks

PubMed Central

Sadrawi, Muammar; Fan, Shou-Zen; Abbod, Maysam F.; Jen, Kuo-Kuang; Shieh, Jiann-Shing

2015-01-01

This study evaluated the depth of anesthesia (DoA) index using artificial neural networks (ANN) which is performed as the modeling technique. Totally 63-patient data is addressed, for both modeling and testing of 17 and 46 patients, respectively. The empirical mode decomposition (EMD) is utilized to purify between the electroencephalography (EEG) signal and the noise. The filtered EEG signal is subsequently extracted to achieve a sample entropy index by every 5-second signal. Then, it is combined with other mean values of vital signs, that is, electromyography (EMG), heart rate (HR), pulse, systolic blood pressure (SBP), diastolic blood pressure (DBP), and signal quality index (SQI) to evaluate the DoA index as the input. The 5 doctor scores are averaged to obtain an output index. The mean absolute error (MAE) is utilized as the performance evaluation. 10-fold cross-validation is performed in order to generalize the model. The ANN model is compared with the bispectral index (BIS). The results show that the ANN is able to produce lower MAE than BIS. For the correlation coefficient, ANN also has higher value than BIS tested on the 46-patient testing data. Sensitivity analysis and cross-validation method are applied in advance. The results state that EMG has the most effecting parameter, significantly. PMID:26568957

Adaptive bearing estimation and tracking of multiple targets in a realistic passive sonar scenario

NASA Astrophysics Data System (ADS)

Rajagopal, R.; Challa, Subhash; Faruqi, Farhan A.; Rao, P. R.

1997-06-01

In a realistic passive sonar environment, the received signal consists of multipath arrivals from closely separated moving targets. The signals are contaminated by spatially correlated noise. The differential MUSIC has been proposed to estimate the DOAs in such a scenario. This method estimates the 'noise subspace' in order to estimate the DOAs. However, the 'noise subspace' estimate has to be updated as and when new data become available. In order to save the computational costs, a new adaptive noise subspace estimation algorithm is proposed in this paper. The salient features of the proposed algorithm are: (1) Noise subspace estimation is done by QR decomposition of the difference matrix which is formed from the data covariance matrix. Thus, as compared to standard eigen-decomposition based methods which require O(N3) computations, the proposed method requires only O(N2) computations. (2) Noise subspace is updated by updating the QR decomposition. (3) The proposed algorithm works in a realistic sonar environment. In the second part of the paper, the estimated bearing values are used to track multiple targets. In order to achieve this, the nonlinear system/linear measurement extended Kalman filtering proposed is applied. Computer simulation results are also presented to support the theory.

Longpath-DOAS measurements of BrO on the westcoast of Ireland

NASA Astrophysics Data System (ADS)

Buxmann, J.; Seitz, K.; Poehler, D.; Platt, U.

2009-04-01

Reactive halogen species (RHS) are of great importance since they influence the atmospheric ozone chemistry. The involved processes are not fully understood yet. Two field campaigns were undertaken at the west coast of Ireland at Mace Head research station and the Martin Ryan Institute (Carna, County Galway) respectively between August and September of 2007. During both campaigns the RHS BrO was investigated by active Differential Optical Absorption Spectroscopy (DOAS) in the marine boundary layer. Expecting very low concentrations of BrO, a low detection limit is necessary. By using a special strategy and an optimized configuration of the instruments, noise was significantly reduced compared to earlier investigations. Boundary layer BrO was detected at peak concentrations of (6,9 ± 1,7) ppt at both measurement sites in the late afternoon and early morning. Furthermore there was an ozone depletion event on August 24th from 40 ppb down to 10 ppb connected with high IO concentrations at the Martin Ryan Institute. At Mace Head diurnal profiles of BrO were measured for 8 days. An anticorrelation with Ozone concentrations was found. During the same period BrO also exceeded the detection limit during three nights reaching levels up to (3 ± 1,2) ppt. Possible causes of this observation are discussed.

Evaluation of the on-site immunoassay drug-screening device Triage-TOX in routine forensic autopsy.

PubMed

Tominaga, Mariko; Michiue, Tomomi; Maeda, Hitoshi

2015-11-01

Instrumental identification of drugs with quantification is essential in forensic toxicology, while on-site immunoassay urinalysis drug-screening devices conveniently provide preliminary information when adequately used. However, suitable or sufficient urine specimens are not always available. The present study evaluated the efficacy of a new on-site immunoassay drug-screening device Triage-TOX (Alere Inc., San Diego, CA, USA), which has recently been developed to provide objective data on the one-step automated processor, using 51 urine and 19 pericardial fluid samples from 66 forensic autopsy cases, compared with Triage-Drug of Abuse (DOA) and Monitect-9. For benzodiazepines, the positive predictive value and specificity of Triage-TOX were higher than those of Triage-DOA; however, sensitivity was higher with Monitect-9, despite frequent false-positives. The results for the other drugs with the three devices also included a few false-negatives and false-positives. These observations indicate the applicability of Triage-TOX in preliminary drug screening using urine or alternative materials in routine forensic autopsy, when a possible false-negative is considered, especially for benzodiazepines, providing objective information; however, the combined use of another device such as Monitect-9 can help minimize misinterpretation prior to instrumental analysis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Intercomparison of NO3 radical detection instruments in the atmosphere simulation chamber SAPHIR

NASA Astrophysics Data System (ADS)

Dorn, H.-P.; Apodaca, R. L.; Ball, S. M.; Brauers, T.; Brown, S. S.; Crowley, J. N.; Dubé, W. P.; Fuchs, H.; Häseler, R.; Heitmann, U.; Jones, R. L.; Kiendler-Scharr, A.; Labazan, I.; Langridge, J. M.; Meinen, J.; Mentel, T. F.; Platt, U.; Pöhler, D.; Rohrer, F.; Ruth, A. A.; Schlosser, E.; Schuster, G.; Shillings, A. J. L.; Simpson, W. R.; Thieser, J.; Tillmann, R.; Varma, R.; Venables, D. S.; Wahner, A.

2013-05-01

The detection of atmospheric NO3 radicals is still challenging owing to its low mixing ratios (≈ 1 to 300 pptv) in the troposphere. While long-path differential optical absorption spectroscopy (DOAS) has been a well-established NO3 detection approach for over 25 yr, newly sensitive techniques have been developed in the past decade. This publication outlines the results of the first comprehensive intercomparison of seven instruments developed for the spectroscopic detection of tropospheric NO3. Four instruments were based on cavity ring-down spectroscopy (CRDS), two utilised open-path cavity-enhanced absorption spectroscopy (CEAS), and one applied "classical" long-path DOAS. The intercomparison campaign "NO3Comp" was held at the atmosphere simulation chamber SAPHIR in Jülich (Germany) in June 2007. Twelve experiments were performed in the well-mixed chamber for variable concentrations of NO3, N2O5, NO2, hydrocarbons, and water vapour, in the absence and in the presence of inorganic or organic aerosol. The overall precision of the cavity instruments varied between 0.5 and 5 pptv for integration times of 1 s to 5 min; that of the DOAS instrument was 9 pptv for an acquisition time of 1 min. The NO3 data of all instruments correlated excellently with the NOAA-CRDS instrument, which was selected as the common reference because of its superb sensitivity, high time resolution, and most comprehensive data coverage. The median of the coefficient of determination (r2) over all experiments of the campaign (60 correlations) is r2 = 0.981 (quartile 1 (Q1): 0.949; quartile 3 (Q3): 0.994; min/max: 0.540/0.999). The linear regression analysis of the campaign data set yielded very small intercepts (median: 1.1 pptv; Q1/Q3: -1.1/2.6 pptv; min/max: -14.1/28.0 pptv), and the slopes of the regression lines were close to unity (median: 1.01; Q1/Q3: 0.92/1.10; min/max: 0.72/1.36). The deviation of individual regression slopes from unity was always within the combined accuracies of each instrument pair. The very good correspondence between the NO3 measurements by all instruments for aerosol-free experiments indicates that the losses of NO3 in the inlet of the instruments were determined reliably by the participants for the corresponding conditions. In the presence of inorganic or organic aerosol, however, differences in the measured NO3 mixing ratios were detectable among the instruments. In individual experiments the discrepancies increased with time, pointing to additional NO3 radical losses by aerosol deposited onto the filters or on the inlet walls of the instruments. Instruments using DOAS analyses showed no significant effect of aerosol on the detection of NO3. No hint of a cross interference of NO2 was found. The effect of non-Lambert-Beer behaviour of water vapour absorption lines on the accuracy of the NO3 detection by broadband techniques was small and well controlled. The NO3Comp campaign demonstrated the high quality, reliability and robustness of performance of current state-of-the-art instrumentation for NO3 detection.

Intercomparison of four airborne imaging DOAS systems for tropospheric NO2 mapping - First results of the AROMAPEX campaign

NASA Astrophysics Data System (ADS)

Tack, Frederik; Merlaud, Alexis; Meier, Andreas; Ge, Xinrui; Meuleman, Koen; Ruhtz, Thomas; van der Wal, Len; Van Roozendael, Michel; Iordache, Daniel; Schönhardt, Anja; Richter, Andreas; Vlemmix, Tim; de Goeij, Bryan; Ardelean, Magdalena; Boscornea, Andreea; Constantin, Daniel; Shaifangar, Reza; Wagner, Thomas; Lampel, Johannes; Schuettemeyer, Dirk

2017-04-01

The AROMAPEX campaign took place in Berlin in April, 2016, co-funded by the EU (EUFAR) and ESA, with the primary objective to intercompare experimental airborne atmospheric imagers dedicated to the mapping of the spatial distribution of tropospheric nitrogen dioxide (NO2). AROMAPEX is also a preparatory step for forthcoming intercomparison/validation campaigns of satellite air quality sensors, such as TROPOMI (TROPOspheric Monitoring Instrument). The instruments were operated from two planes, performing synchronized flights: APEX (VITO/BIRA-IASB) was operated from DLR's DO-228 D-CFFU plane at 6.1 km altitude while AirMAP (IUP Bremen), and the small, lightweight SWING (BIRA-IASB) and Spectrolite (TNO/TU Delft) instruments were operated from the FUB Cessna 207T D-EAFU at 3 km. Two synchronized flights took place on 21 April, 2016, the only cloud-free day during the campaign, in the morning from 09:34 to 12:01 LT and in the afternoon from 14:24 to 16:39 LT. APEX, AirMAP and SWING have a comparable swath width of 3 km, while Spectrolite has a swath of 450 m due to the fact that the field-of-view had to be reduced from 40° to 8.3° for practical reasons. The spatial resolution is approximately 100 m after spatial aggregation for APEX, AirMAP and Spectrolite (pushbroom scanning), and 300 m for SWING (whiskbroom scanning). The airborne Sunphotometer FUBISS-ASA2 was installed and operated during the ascent and descent of the FUB aircraft to derive aerosol optical depth (AOD). During the overpass of the imagers, simultaneous car mobile-DOAS observations were performed with three systems covering transects from north to south and west to east. The ground-based instrumental set-up was completed by a DOAS instrument, an Aeronet station and a ceilometer installed at the rooftop of FUB, located in the southwest of Berlin. The AROMAPEX experiment builds on the experience gained during the AROMAT campaigns held in September, 2014 and August, 2015 in Romania, and the BUMBA campaigns held in April, 2015 and July, 2016 in Belgium. We present first results of an intercomparison study of both the NO2 slant column densities (SCDs) and vertical column densities (VCDs) retrieved from the APEX, AirMAP, SWING and Spectrolite instruments. Two large NO2 plumes, crossing the city from west to east, were detected by all imaging systems with high consistency. Retrieved NO2 VCDs range between 1.5 x 1015 and 2.4 x 1016 molec cm-2. For the sake of harmonizing the different data sets, efforts are currently ongoing to agree on a common set of parameter settings, gridding algorithm and AMF LUT in the NO2 retrieval approach. Despite these efforts, discrepancies will remain due to a combination of (1) instrumental differences, e.g. SNR, spatial and spectral resolution; (2) algorithmic differences, e.g. DOAS fitting, RTM, a priori input; and (3) observation differences, e.g. flight altitude, overpass time and viewing geometry.

Nitrous Oxide-Oxygen Sedation: USAF Dental Guidelines.

DTIC Science & Technology

1981-11-01

prosthodontic tooth o rd ...r. 1-,t doA ,stry. Also, N20-0, sedation can be used a- . :., :> , ires -uch as periodontal scaling, orthodontic ad. ’ ci ... of...amnesia Plane 3 - total analgesia and amnesia; leads to loss of consciousness II - dream and/or delirium (unconsciousness) III - surgical (four depths...obtain N20. Cylinders can be bought without question at surgical supply houses. People without means but with desire and opportunity turn to theft. A

Triple Helix

DTIC Science & Technology

2008-08-01

and sponsoring FIRST teams at the Junior FIRST Lego League (JFLL) and the FIRST Lego League (FLL) levels in elementary and middle school . As such, the...a Final Technical Report for Year I Grant W911NF-07-1-0663 with the Newport News Public School District for the Menchville High School Robotics Team...August 2008 TRIPL HELIX 0 Menchville High School Newport News, VA 20080829081 w DEFENSE TECHNICAL INFORMATION CENTER bfro do.A icfr tkw, Def&*ue, Cow

Method and Apparatus for Reducing Noise from Near Ocean Surface Sources

DTIC Science & Technology

2001-10-01

reducing the acoustic noise from near-surface 4 sources using an array processing technique that utilizes 5 Multiple Signal Classification ( MUSIC ...sources without 13 degrading the signal level and quality of the TOI. The present 14 invention utilizes a unique application of the MUSIC beamforming...specific algorithm that utilizes a 5 MUSIC technique and estimates the direction of arrival (DOA) of 6 the acoustic signal signals and generates output

Elucidation of the Dynamics for Hot-Spot Initiation at Nonuniform Interfaces of Highly Shocked Materials

DTIC Science & Technology

2011-12-07

with nonuniform interfaces plays an essential role in the interfacial instabilities in iner- tial confinement fusion (ICF), in shock-induced...involved in interfacial instabilities at the atomic scale, providing insights on such phenomenon. Thus ReaxFF provides the possibility of realistic...calculations was also performed on the IPDI and DOA to determine the charges and structures for the binder model. These QM results and model preparation

Elucidation of the Dynamics for Hot-Spot Initiation at Nonuniform Interfaces of Highly Shocked Materials

DTIC Science & Technology

2011-12-07

with nonuniform interfaces plays an essential role in the interfacial instabilities in iner- tial confinement fusion (ICF), in shock-induced...involved in interfacial instabilities at the atomic scale, providing insights on such phenomenon. Thus ReaxFF provides the possibility of realistic...on the IPDI and DOA to determine the charges and structures for the binder model. These QM results and model preparation procedure are provided as part

The History of Structural Fatigue Testing at Fishermans Bend Australia

DTIC Science & Technology

2005-10-01

Aviation DH de Havilland Aircraft (UK) DOA Department of Aviation DSTO Defence Science and Technology Organisation ESH Equivalent Service Hours...gave early evidence of the truth of Mr. Wills’s predictions and greatly influenced the fatigue research programme. In October 1951 a de Havilland (DH...crack growth [22]. At about this time (in 1953) fatigue failures occurred in the fuselage of the DH Comet which led to the loss of two aircraft with

Inorganic Iodine and Bromine in the Tropical Upper Troposphere/Lower Stratosphere Derived From Balloon Borne Observations

NASA Astrophysics Data System (ADS)

Dorf, M.; Butz, A.; Camy-Peyret, C.; Chipperfield, M.; Kreycy, S.; Kritten, L.; Prados-Roman, C.; Pfeilsticker, K.

2008-12-01

Due to the ozone destroying capabilities of bromine and iodine bearing compounds, the stratospheric budget of inorganic bromine and iodine is of major interest for modeling ozone depletion and assessing the future evolution of the ozone layer. In particular the contribution of very short lived substances (VSLS) to the bromine budget has recently been shown to enhance ozone depletion in mid-latitudes and polar regions. So far, iodine species have not been unambiguously detected in the stratosphere with upper limits for total inorganic iodine (Iy) of about 0.1 ppt. However, observations are sparse and mainly restricted to mid- and high-latitudes. Here, we assess the budget of iodine and bromine in the tropical Upper Troposphere/ Lower Stratosphere (UT/LS) where the halogen source gases enter the stratosphere and supply the stratosphere with halogen species. We report on two stratospheric balloon flights of the LPMA/DOAS (Limb Profile Monitor of the Atmosphere/Differential Optical Absorption Spectrometer) payload from a tropical station in northern Brazil (5°S, 43°W) in June 2005 and June 2008. There, the LPMA/DOAS payload conducted spectroscopic direct sun measurements in the UV/visible and infrared spectral range during balloon ascent and in solar occultation geometry. The LPMA/DOAS observations allow for the retrieval of IO and OIO from their absorption features in the visible spectral range. Neither species could be detected unambiguously with detection limits ranging between 0.01 and 0.2 ppt in the UT/LS. Constraining a stratospheric chemistry model by the inferred detection limits for IO and OIO, yields an upper limit for Iy of 0.1 to 0.3 ppt. Implications for stratospheric ozone are discussed on the basis of model studies. BrO is inferred from absorption bands in the UV spectral range yielding the first BrO vertical profile in the tropical UT/LS. For the balloon flight in June 2005, total inorganic bromine (Bry) is estimated to (21.5 ± 2.5) ppt in 4.5-year-old air using a stratospheric model constrained by measured BrO. We derive a total contribution of (5.2 ± 2.5) ppt from brominated VSLS and inorganic product gases to Bry. Tropospheric BrO was found to be < 1 ppt. Our results are compared to 3-D CTM SLIMCAT model runs.

Monitoring shipping emissions in the German Bight using MAX-DOAS measurements

NASA Astrophysics Data System (ADS)

Seyler, André; Wittrock, Folkard; Kattner, Lisa; Mathieu-Üffing, Barbara; Peters, Enno; Richter, Andreas; Schmolke, Stefan; Burrows, John P.

2017-04-01

Shipping is generally the most energy efficient transportation mode, but, at the same time, it accounts for four fifths of the worldwide total merchandise trade volume. As a result, shipping contributes a significant part to the emissions from the transportation sector. The majority of shipping emissions occurs within 400 km of land, impacting on air pollution in coastal areas and harbor towns. The North Sea has one of the highest ship densities in the world and the vast majority of ships heading for the port of Hamburg sail through the German Bight and into the river Elbe. A three-year time series of ground-based MAX-DOAS measurements of NO2 and SO2 on the island Neuwerk in the German Bight has been analyzed for contributions from shipping emissions. Measurements of individual ship plumes as well as of background pollution are possible from this location, which is 6-7 kilometers away from the main shipping lane towards the harbor of Hamburg. More than 2000 individual ship plumes have been identified in the data and analyzed for the emission ratio of SO2 to NO2, yielding an average ratio of 0.3 for the years 2013/2014. Contributions of ships and land-based sources to air pollution levels in the German Bight have been estimated, showing that despite the vicinity to the shipping lane, the contribution of shipping sources to air pollution is only about 40%. Since January 2015, much lower fuel sulfur content limits of 0.1% (before: 1.0%) apply in the North and Baltic Sea Emission Control Area (ECA). Comparing MAX-DOAS measurements from 2015/2016 (new regulation) to 2013/2014 (old regulation), a large reduction in SO2/NO2 ratios in shipping emissions and a significant reduction (by a factor of eight) in ambient coastal SO2 levels have been observed. In addition to that, selected shipping emission measurements from other measurement sites and campaigns are presented. This study is part of the project MeSMarT (Measurements of Shipping emissions in the Marine Troposphere), a cooperation between the University of Bremen and the Federal Maritime and Hydrographic Agency (Bundesamt für Seeschifffahrt und Hydrographie, BSH), supported by the Helmholtz Zentrum Geesthacht (HZG).

Program Budgeting within the Department of the Navy

DTIC Science & Technology

1989-06-01

incremental increases in bidgets . When a popular call goes out for a 600 ship navy, a strategic defense initiative, or a B-2 bomber, this is the time...Previously defense budgets had been formulated by j focusing on the existing base and adding incremental improvements to it. The whole question of how much a...the aggregate budgets appeared to change in smooth increments , they found great variations in the budgets of the agencies which make up the DOA. They

Ignition and Flameholding in a Supersonic Combustor by an Electrical Discharge Combined with a Fuel Injector

DTIC Science & Technology

2014-01-01

W.F. O’Brien, J.A. Schetz - Plasma torch atomizer-igniter for supersonic combustion of liquid hydrocarbon fuels // AIAA Paper 2006-7970. 6. H. Do...A. Deminsky, I. V. Kochetov, A. P. Napartovich, S. B. Leonov, - “Modeling of Plasma Assisted Combustion in Premixed Supersonic Gas Flow...1 Ignition and Flameholding in a Supersonic Combustor by an Electrical Discharge Combined with a Fuel Injector K. V. Savelkin 1 , D. A

Benzocaine-Induced Methemoglobinemia Attributed to Topical Application of the Anesthetic in Several Laboratory Animal Species

DTIC Science & Technology

1993-01-01

SAD-A273 571 T PON AGE DoaM No o,.Q ’a J 0Lt)141 IF( AND UAItS COVIAto 4. TITLE AND SUBfII( 5 FUNDING NUMBERS Benzocaine -inducd methemoglobinemia...PUBLIC RELEASE: DISTRIBUTION UNLIMITED * 13. ABSTRACT (Mj,,mum 200 wotds) Case reports of benzocaine -induced methemoglobinemia following application...for several types of experimental studies. We designed a screening study using a common topical benzocaine -contzining anesthetics. Response to

Atmospheric NO2 profiles measured with lidar during the CINDI-2 campaign

NASA Astrophysics Data System (ADS)

Berkhout, A. J. C.; Gast, L. F. L.; van der Hoff, G. R.; Swart, D. P. J.; Hoed, M.; Allaart, M.

2018-04-01

From 12 to 28 September 2016, the CINDI-2 NO2 intercomparison campaign took place at the Cabauw research site in the Netherlands. Aimed principally at MAX-DOAS instruments, other techniques participated as well. The RIVM mobile lidar measured atmospheric NO2 profiles on six campaign days. Results show the development of NO2 concentrations during the day, as well as layered structures in the profiles. These were compared with profiles from other instruments.

Assessment of turkey vehicle container microclimate on transit during summer season conditions

NASA Astrophysics Data System (ADS)

Carvalho, Rafael H.; Honorato, Danielle C. B.; Guarnieri, Paulo D.; Soares, Adriana L.; Pedrão, Mayka R.; Oba, Alexandre; Paião, Fernanda G.; Ida, Elza I.; Shimokomaki, Massami

2018-06-01

This study evaluated the formed microclimate commercial truck transport practices effects on the turkeys' welfare by measuring Dead on Arrival (DOA) index and pale, soft, and exudative (PSE-like) meat occurrence. The experimental design was entirely randomized in a 6 × 2 factorial arrangements (two truck container compartments × six water shower groups) with birds positioned at superior front (SF), inferior front (IF), superior middle (SM), inferior middle (IM), superior rear (SR), and inferior rear (IR) and two bath treatments: with water shower (WiS) and without water shower (WoS) with eight replications for each treatment. The animals were transported for 95 min' journey from the farm to the slaughterhouse under hot-humidity conditions. The results shown herein indicated the formation of a thermal core at the inferior middle and rear truck container regions, because the heat produced by the birds and the influence of developed microclimate consisting of temperature, relative humidity, and air ventilation. The IM and IR container compartments under the WoS treatment presented the highest ( P < 0.01) numbers of PSE-like meat incidence and DOA index values compared with those located at the front under WiS treatment as the consequence of the altered to birds unbearable conditions within the container microclimate in transit. The formed microclimate during the commercial transport practices under hot-humidity conditions affected the bird's welfare consequently turkey meat qualities.

Efficacy of bladder neck incision on urodynamic abnormalities in patients with posterior urethral valves.

PubMed

Sarin, Yogesh K; Sinha, Shalini

2013-04-01

This study aims to study the efficacy of simultaneous endoscopic bladder neck incision (BNI) and primary endoscopic valve incision (PEVI) in patients with posterior urethral valves (PUV). Nine PUV patients underwent PEVI and BNI over a year. They were compared to nine comparable historical controls that had undergone only PEVI. Trends in renal function tests, urodynamics and changes in the upper urinary tracts were evaluated after 3 months during which no pharmacotherapy was given. The incidence of bladder dysfunction in the two groups was similar-55.5 % in case group and 66.6 % in control group. Hypocompliant, high-pressure bladder was the predominant cystometric finding in both groups. Three patients in the case group and two patients in the control group had high end infusion pressure (EIP) with poor compliance. Detrusor overactivity (DOA) was seen in 23.1 % patients in the case group as compared to 55.5 % patients in the control group (P = 0.3348). Five patients in both groups were later started on anticholinergics due to raised EIP, small capacity bladder and/or DOA. Although BNI should theoretically improve the outcome of PUV patients, the current pilot study failed to demonstrate any significant difference. A larger sample size and longer follow-up are required to prove or disprove its efficacy.

Intra-pixel variability in satellite tropospheric NO2 column densities derived from simultaneous space-borne and airborne observations over the South African Highveld

NASA Astrophysics Data System (ADS)

Broccardo, Stephen; Heue, Klaus-Peter; Walter, David; Meyer, Christian; Kokhanovsky, Alexander; van der A, Ronald; Piketh, Stuart; Langerman, Kristy; Platt, Ulrich

2018-05-01

Aircraft measurements of NO2 using an imaging differential optical absorption spectrometer (iDOAS) instrument over the South African Highveld region in August 2007 are presented and compared to satellite measurements from OMI and SCIAMACHY. In situ aerosol and trace-gas vertical profile measurements, along with aerosol optical thickness and single-scattering albedo measurements from the Aerosol Robotic Network (AERONET), are used to devise scenarios for a radiative transfer modelling sensitivity study. Uncertainty in the air-mass factor due to variations in the aerosol and NO2 profile shape is constrained and used to calculate vertical column densities (VCDs), which are compared to co-located satellite measurements. The lower spatial resolution of the satellites cannot resolve the detailed plume structures revealed in the aircraft measurements. The airborne DOAS in general measured steeper horizontal gradients and higher peak NO2 vertical column density. Aircraft measurements close to major sources, spatially averaged to the satellite resolution, indicate NO2 column densities more than twice those measured by the satellite. The agreement between the high-resolution aircraft instrument and the satellite instrument improves with distance from the source, this is attributed to horizontal and vertical dispersion of NO2 in the boundary layer. Despite the low spatial resolution, satellite images reveal point sources and plumes that retain their structure for several hundred kilometres downwind.

Nitrous acid measurements in urban Los Angeles using novel techniques

NASA Astrophysics Data System (ADS)

Young, C. J.; Washenfelder, R. A.; Brown, S. S.; Veres, P. R.; Cochran, A. K.; Roberts, J. M.; Pikelnaya, O.; Tsai, C.; Stutz, J.; Afif, C.; Michoud, V.; Borbon, A.

2010-12-01

Nitrous acid (HONO) is an important player in tropospheric photochemistry, as it is a source of hydroxyl radicals. Thus, accurate measurements of HONO and its sources and sinks are critical to fully understand tropospheric oxidation processes. Differential optical absorption spectroscopy (DOAS) has been used to measure HONO in the field over the past two decades, yielding much of the current knowledge about the molecule and its sources. In situ measurements with high sensitivity, time resolution and minimal interferences can provide further information about HONO sources and sinks. One method that could satisfy these criteria is incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS). IBBCEAS combines the sensitivity of cavity-enhanced techniques with the specificity of spectral resolution. The application of IBBCEAS to laboratory HONO measurements has been demonstrated, but the technique has not yet been used to detect HONO in the field. A two-channel instrument was custom-built for field measurements of HONO, with the first channel a 365 nm-centred IBBCEAS to measure HONO and NO2 and the second channel a 403 nm cavity ring-down spectrometer for an independent measure of NO2. The instrument was successfully deployed at the CalNex Pasadena ground site in May and June, 2010. Measurements compared well with previously validated HONO instrumentation, including DOAS, negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS) and a wet-chemical, derivitization system with HPLC detection (NitroMAC).

Assessment of turkey vehicle container microclimate on transit during summer season conditions

NASA Astrophysics Data System (ADS)

Carvalho, Rafael H.; Honorato, Danielle C. B.; Guarnieri, Paulo D.; Soares, Adriana L.; Pedrão, Mayka R.; Oba, Alexandre; Paião, Fernanda G.; Ida, Elza I.; Shimokomaki, Massami

2018-01-01

This study evaluated the formed microclimate commercial truck transport practices effects on the turkeys' welfare by measuring Dead on Arrival (DOA) index and pale, soft, and exudative (PSE-like) meat occurrence. The experimental design was entirely randomized in a 6 × 2 factorial arrangements (two truck container compartments × six water shower groups) with birds positioned at superior front (SF), inferior front (IF), superior middle (SM), inferior middle (IM), superior rear (SR), and inferior rear (IR) and two bath treatments: with water shower (WiS) and without water shower (WoS) with eight replications for each treatment. The animals were transported for 95 min' journey from the farm to the slaughterhouse under hot-humidity conditions. The results shown herein indicated the formation of a thermal core at the inferior middle and rear truck container regions, because the heat produced by the birds and the influence of developed microclimate consisting of temperature, relative humidity, and air ventilation. The IM and IR container compartments under the WoS treatment presented the highest (P < 0.01) numbers of PSE-like meat incidence and DOA index values compared with those located at the front under WiS treatment as the consequence of the altered to birds unbearable conditions within the container microclimate in transit. The formed microclimate during the commercial transport practices under hot-humidity conditions affected the bird's welfare consequently turkey meat qualities.

Assessment of turkey vehicle container microclimate on transit during summer season conditions.

PubMed

Carvalho, Rafael H; Honorato, Danielle C B; Guarnieri, Paulo D; Soares, Adriana L; Pedrão, Mayka R; Oba, Alexandre; Paião, Fernanda G; Ida, Elza I; Shimokomaki, Massami

2018-06-01

This study evaluated the formed microclimate commercial truck transport practices effects on the turkeys' welfare by measuring Dead on Arrival (DOA) index and pale, soft, and exudative (PSE-like) meat occurrence. The experimental design was entirely randomized in a 6 × 2 factorial arrangements (two truck container compartments × six water shower groups) with birds positioned at superior front (SF), inferior front (IF), superior middle (SM), inferior middle (IM), superior rear (SR), and inferior rear (IR) and two bath treatments: with water shower (WiS) and without water shower (WoS) with eight replications for each treatment. The animals were transported for 95 min' journey from the farm to the slaughterhouse under hot-humidity conditions. The results shown herein indicated the formation of a thermal core at the inferior middle and rear truck container regions, because the heat produced by the birds and the influence of developed microclimate consisting of temperature, relative humidity, and air ventilation. The IM and IR container compartments under the WoS treatment presented the highest (P < 0.01) numbers of PSE-like meat incidence and DOA index values compared with those located at the front under WiS treatment as the consequence of the altered to birds unbearable conditions within the container microclimate in transit. The formed microclimate during the commercial transport practices under hot-humidity conditions affected the bird's welfare consequently turkey meat qualities.

GOME Total Ozone and Calibration Error Derived Usign Version 8 TOMS Algorithm

NASA Technical Reports Server (NTRS)

Gleason, J.; Wellemeyer, C.; Qin, W.; Ahn, C.; Gopalan, A.; Bhartia, P.

2003-01-01

The Global Ozone Monitoring Experiment (GOME) is a hyper-spectral satellite instrument measuring the ultraviolet backscatter at relatively high spectral resolution. GOME radiances have been slit averaged to emulate measurements of the Total Ozone Mapping Spectrometer (TOMS) made at discrete wavelengths and processed using the new TOMS Version 8 Ozone Algorithm. Compared to Differential Optical Absorption Spectroscopy (DOAS) techniques based on local structure in the Huggins Bands, the TOMS uses differential absorption between a pair of wavelengths including the local stiucture as well as the background continuum. This makes the TOMS Algorithm more sensitive to ozone, but it also makes the algorithm more sensitive to instrument calibration errors. While calibration adjustments are not needed for the fitting techniques like the DOAS employed in GOME algorithms, some adjustment is necessary when applying the TOMS Algorithm to GOME. Using spectral discrimination at near ultraviolet wavelength channels unabsorbed by ozone, the GOME wavelength dependent calibration drift is estimated and then checked using pair justification. In addition, the day one calibration offset is estimated based on the residuals of the Version 8 TOMS Algorithm. The estimated drift in the 2b detector of GOME is small through the first four years and then increases rapidly to +5% in normalized radiance at 331 nm relative to 385 nm by mid 2000. The lb detector appears to be quite well behaved throughout this time period.

Intrinsic coincident full-Stokes polarimeter using stacked organic photovoltaics and architectural comparison of polarimeter techniques

NASA Astrophysics Data System (ADS)

Yang, Ruonan; Sen, Pratik; O'Connor, B. T.; Kudenov, M. W.

2017-08-01

An intrinsic coincident full-Stokes polarimeter is demonstrated by using stain-aligned polymer-based organic photovoltaics (OPVs) which can preferentially absorb certain polarized states of incident light. The photovoltaic-based polarimeter is capable of measuring four stokes parameters by cascading four semitransparent OPVs in series along the same optical axis. Two wave plates were incorporated into the system to modulate the S3 stokes parameter so as to reduce the condition number of the measurement matrix. The model for the full-Stokes polarimeter was established and validated, demonstrating an average RMS error of 0.84%. The optimization, based on minimizing the condition number of the 4-cell OPV design, showed that a condition number of 2.4 is possible. Performance of this in-line polarimeter concept was compared to other polarimeter architectures, including Division of Time (DoT), Division of Amplitude (DoAm), Division of Focal Plane (DoFP), and Division of Aperture (DoA) from signal-to-noise ratio (SNR) perspective. This in-line polarimeter concept has the potential to enable both high temporal (as compared with a DoT polarimeter) and high spatial resolution (as compared with DoFP and DoA polarimeters). We conclude that the intrinsic design has the same √2 SNR advantage as the DoAm polarimeter, but with greater compactness.

Observation of NO3 radicals by LP-DOAS during CAREBEIJING 2014

NASA Astrophysics Data System (ADS)

Lu, Xue; Qin, Min; Xie, Pinhua; Duan, Jun; Fang, Wu; Liu, Jianguo; Liu, Wenqing

2016-04-01

NO3 radical is a significant species during night, affecting the formation of secondary organic aerosol (SOA) in night. It is also the most pivotal oxidation in night, involved in the removal process of NOx and VOCs, which is directly related to atmosphere cleanliness. During the CAREBEIJING field campaign (June 5 - July 10, 2014), NO3 radical was measured with a long path differential optical absorption spectroscopy (LP-DOAS) at Wangdu Site (38.68°N; 115.18°E) in the north of China. In this poster, the principle and fitting analyses of LPDOAS were presented; a retrieval example and a time series of NO3 radicals' concentration with good continuity were showed. The detection limit (1σ) of NO3 with 3.4km optical path is 3.4ppt. The observed mean NO3 mixing ratios were 21 ppt. Under the assumption of steady state, the NO3 production rates were calculated averaging at 1.013ppb/h. The calculated NO3 lifetime has an average of 102.6 s. The correlation between the NO3 mixing ratio and its production rates is about 0.78, which indicates the importance of direct sinks. However, the slope of the logarithmic correlation between NO3 lifetime and NO2 mixing ratio is -0.44, revealing the removal of NO3 is not strongly dependent on the indirect loss process herein.

The CU 2-D-MAX-DOAS instrument - Part 2: Raman scattering probability measurements and retrieval of aerosol optical properties

NASA Astrophysics Data System (ADS)

Ortega, Ivan; Coburn, Sean; Berg, Larry K.; Lantz, Kathy; Michalsky, Joseph; Ferrare, Richard A.; Hair, Johnathan W.; Hostetler, Chris A.; Volkamer, Rainer

2016-08-01

The multiannual global mean of aerosol optical depth at 550 nm (AOD550) over land is ˜ 0.19, and that over oceans is ˜ 0.13. About 45 % of the Earth surface shows AOD550 smaller than 0.1. There is a need for measurement techniques that are optimized to measure aerosol optical properties under low AOD conditions. We present an inherently calibrated retrieval (i.e., no need for radiance calibration) to simultaneously measure AOD and the aerosol phase function parameter, g, based on measurements of azimuth distributions of the Raman scattering probability (RSP), the near-absolute rotational Raman scattering (RRS) intensity. We employ radiative transfer model simulations to show that for solar azimuth RSP measurements at solar elevation and solar zenith angle (SZA) smaller than 80°, RSP is insensitive to the vertical distribution of aerosols and maximally sensitive to changes in AOD and g under near-molecular scattering conditions. The University of Colorado two-dimensional Multi-AXis Differential Optical Absorption Spectroscopy (CU 2-D-MAX-DOAS) instrument was deployed as part of the Two Column Aerosol Project (TCAP) at Cape Cod, MA, during the summer of 2012 to measure direct sun spectra and RSP from scattered light spectra at solar relative azimuth angles (SRAAs) between 5 and 170°. During two case study days with (1) high aerosol load (17 July, 0.3 < AOD430 < 0.6) and (2) near-molecular scattering conditions (22 July, AOD430 < 0.13) we compare RSP-based retrievals of AOD430 and g with data from a co-located CIMEL sun photometer, Multi-Filter Rotating Shadowband Radiometer (MFRSR), and an airborne High Spectral Resolution Lidar (HSRL-2). The average difference (relative to DOAS) for AOD430 is +0.012 ± 0.023 (CIMEL), -0.012 ± 0.024 (MFRSR), -0.011 ± 0.014 (HSRL-2), and +0.023 ± 0.013 (CIMELAOD - MFRSRAOD) and yields the following expressions for correlations between different instruments: DOASAOD = -(0.019 ± 0.006) + (1.03 ± 0.02) × CIMELAOD (R2 = 0.98), DOASAOD = -(0.006 ± 0.005) + (1.08 ± 0.02) × MFRSRAOD (R2 = 0.98), and CIMELAOD = (0.013 ± 0.004) + (1.05 ± 0.01) × MFRSRAOD (R2 = 0.99). The average g measured by DOAS on both days was 0.66 ± 0.03, with a difference of 0.014 ± 0.05 compared to CIMEL. Active steps to minimize the error in the RSP help to reduce the uncertainty in retrievals of AOD and g. As AOD decreases and SZA increases, the RSP signal-to-noise ratio increases. At AOD430 ˜ 0.4 and 0.10 the absolute AOD errors are ˜ 0.014 and 0.003 at 70° SZA and 0.02 and 0.004 at 35° SZA. Inherently calibrated, precise AOD and g measurements are useful to better characterize the aerosol direct effect in urban polluted and remote pristine environments.

Detection of Buried Objects by Means of a SAP Technique: Comparing MUSIC- and SVR-Based Approaches

NASA Astrophysics Data System (ADS)

Meschino, S.; Pajewski, L.; Pastorino, M.; Randazzo, A.; Schettini, G.

2012-04-01

This work is focused on the application of a Sub-Array Processing (SAP) technique to the detection of metallic cylindrical objects embedded in a dielectric half-space. The identification of buried cables, pipes, conduits, and other cylindrical utilities, is an important problem that has been extensively studied in the last years. Most commonly used approaches are based on the use of electromagnetic sensing: a set of antennas illuminates the ground and the collected echo is analyzed in order to extract information about the scenario and to localize the sought objects [1]. In a SAP approach, algorithms for the estimation of Directions of Arrival (DOAs) are employed [2]: they assume that the sources (in this paper, currents induced on buried targets) are in the far-field region of the receiving array, so that the received wavefront can be considered as planar, and the main angular direction of the field can be estimated. However, in electromagnetic sensing of buried objects, the scatterers are usually quite near to the antennas. Nevertheless, by dividing the whole receiving array in a suitable number of sub-arrays, and by finding a dominant DOA for each one, it is possible to localize objects that are in the far-field of the sub-array, although being in the near-field of the array. The DOAs found by the sub-arrays can be triangulated, obtaining a set of crossings with intersections condensed around object locations. In this work, the performances of two different DOA algorithms are compared. In particular, a MUltiple SIgnal Classification (MUSIC)-type method [3] and Support Vector Regression (SVR) based approach [4] are employed. The results of a Cylindrical-Wave Approach forward solver are used as input data of the detection procedure [5]. To process the crossing pattern, the region of interest is divided in small windows, and a Poisson model is adopted for the statistical distribution of intersections in the windows. Hypothesis testing procedures are used (imposing a suitable threshold from a desired false-alarm rate), to ascribe each window to the ground or to the sought objects. Numerical results are presented, for a test scenario with a circular-section cylinder in a dielectric half-space. Different values of the ground permittivity, target size, and its position with respect to the receiving array, are considered. Preliminary results on the application of MUSIC and SVR to multiple-object localization are reported. [1] H. Jol, Ground Penetrating Radar: Theory and Applications, Elsevier, Amsterdam, NL, 2009. [2] Gross F.B., Smart Antennas for Wireless Communications, McGraw-Hill, New York 2005. [3] S. Meschino, L. Pajewski, G. Schettini, "Use of a Sub-Array Statistical Approach for the Detection of a Buried Object", Near Surface Geophysics, vol. 8(5), pp. 365-375, 2010. [4] M. Pastorino, A. Randazzo, "A Smart Antenna System for Direction of Arrival Estimation based on a Support Vector Regression," IEEE Trans. Antennas Propagat., vol. 53(7), pp. 2161-2168, 2005. [5] M. Di Vico, F. Frezza, L. Pajewski, G. Schettini, "Scattering by a Finite Set of Perfectly Conducting Cylinders Buried in a Dielectric Half-Space: a Spectral-Domain Solution," IEEE Trans. Antennas Propagat., vol. 53(2), pp. 719-727, 2005.

A Comparison of Nonlinear Filters for Orbit Determination and Estimation

DTIC Science & Technology

1986-06-01

Com- mand uses a nonlinear least squares filter for element set maintenance for all objects orbiting the Earth (3). These objects, including active...initial state vector is the singularly averaged classical orbital element set provided by SPACECOM/DOA. The state vector in this research consists of...GSF (G) - - 26.0 36.7 GSF(A) 32.1 77.4 38.8 59.6 The Air Force Space Command is responsible for main- taining current orbital element sets for about

Low-Cost Radar Sensors for Personnel Detection and Tracking in Urban Areas

DTIC Science & Technology

2007-01-31

progress on the reserach grant "Low-Cost Radar Sensors for Personnel Detection and Tracking in Urban Areas" during the period 1 May 2005 - 31 December...the DOA of target i with respect to the array boresight is given by: O 1sin-1 -/- fD)--F2(. )(1) where d is the spacing between the elements and A, is...wall. A large database was collected for different parameter spaces including number of humans, types of movements, wall types and radar polarization

Localization of Gunfire from Multiple Shooters (ARO Research Topic 5.2, Information Processing and Fusion; STIR Program)

DTIC Science & Technology

2016-03-03

for each shot, as well as "raw" data that includes time-of-arrival (TOA) and direction-of-arrival (DOA) of the muzzle blast (MB) produced by the weapon...angle of arrival, muzzle blast, shock wave, bullet deceleration, fusion REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR...of the muzzle blast (MB) produced by the weapon and the shock wave (SW) produced by the supersonic bullet. The localization accuracy is improved

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, Yasin; Khare, Vaibhav Rai; Mathur, Jyotirmay

The paper describes a parametric study developed to estimate the energy savings potential of a radiant cooling system installed in a commercial building in India. The study is based on numerical modeling of a radiant cooling system installed in an Information Technology (IT) office building sited in the composite climate of Hyderabad. To evaluate thermal performance and energy consumption, simulations were carried out using the ANSYS FLUENT and EnergyPlus softwares, respectively. The building model was calibrated using the measured data for the installed radiant system. Then this calibrated model was used to simulate the energy consumption of a building usingmore » a conventional all-air system to determine the proportional energy savings. For proper handling of the latent load, a dedicated outside air system (DOAS) was used as an alternative to Fan Coil Unit (FCU). A comparison of energy consumption calculated that the radiant system was 17.5 % more efficient than a conventional all-air system and that a 30% savings was achieved by using a DOAS system compared with a conventional system. Computational Fluid Dynamics (CFD) simulation was performed to evaluate indoor air quality and thermal comfort. It was found that a radiant system offers more uniform temperatures, as well as a better mean air temperature range, than a conventional system. To further enhance the energy savings in the radiant system, different operational strategies were analyzed based on thermal analysis using EnergyPlus. Lastly, the energy savings achieved in this parametric run were more than 10% compared with a conventional all-air system.« less

Long-term Studies of Marine Halogen Release

NASA Astrophysics Data System (ADS)

Tschritter, J.; Holla, R.; Frieß, U.; Platt, U.

2009-04-01

Institute of Enviromental Physics, Heidelberg, Germany. Long term measurements of atmospheric trace gases using multi-axis DOAS instruments are pursued at the new SOLAS observatory on the island of Sao Vicente, (Cape Verde). This research is part of the SOPRAN (Surface Ocean Processes in the ANthropocene) project (Fördernummer:03F0462F). Reactive halogen species (RHS) such as bromine- and iodine- containing species play major roles in the chemistry of ozone in both the troposphere and lower stratosphere and thus possibly influence the ozone budget on a global scale. In addition iodine-species emitted from the ocean surface have been shown to be responsible for the production of new atmospheric particles in the marine boundary layer. This may have an effect on cloud formation and radiation transfer on local and global scales. Long term measurements of RHS abundances will help to identify their key regions and processes for formation. A new long term Multi-MAX-DOAS instrument has been installed at the SOLAS observatory on the island of Sao Vicente, (Cape Verde). The main focus of these unique measurements is the investigation of reactive halogen chemistry in the subtropical marine boundary layer based on measurements of BrO, IO, and possibly OIO. Because of its wide spectral range also the use for O4-retrievals to gain aerosol profiles is possible. IO has been detected with mixing ratios up to 1.3 ppt. For BrO an upper limit of 2 ppt could be determined.

EFFECTS OF THE GENIUM MICROPROCESSOR KNEE SYSTEM ON KNEE MOMENT SYMMETRY DURING HILL WALKING.

PubMed

Highsmith, M Jason; Klenow, Tyler D; Kahle, Jason T; Wernke, Matthew M; Carey, Stephanie L; Miro, Rebecca M; Lura, Derek J

2016-09-01

Use of the Genium microprocessor knee (MPK) system reportedly improves knee kinematics during walking and other functional tasks compared to other MPK systems. This improved kinematic pattern was observed when walking on different hill conditions and at different speeds. Given the improved kinematics associated with hill walking while using the Genium, a similar improvement in the symmetry of knee kinetics is also feasible. The purpose of this study was to determine if Genium MPK use would reduce the degree of asymmetry (DoA) of peak stance knee flexion moment compared to the C-Leg MPK in transfemoral amputation (TFA) patients. This study used a randomized experimental crossover of TFA patients using Genium and C-Leg MPKs ( n = 20). Biomechanical gait analysis by 3D motion tracking with floor mounted force plates of TFA patients ambulating at different speeds on 5° ramps was completed. Knee moment DoA was significantly different between MPK conditions in the slow and fast uphill as well as the slow and self-selected downhill conditions. In a sample of high-functioning TFA patients, Genium knee system accommodation and use improved knee moment symmetry in slow speed walking up and down a five degree ramp compared with C-Leg. Additionally, the Genium improved knee moment symmetry when walking downhill at comfortable speed. These results likely have application in other patients who could benefit from more consistent knee function, such as older patients and others who have slower walking speeds.

Nitrogen Dioxide Total Column Over Terra Nova Bay Station - Antarctica - During 2001

NASA Astrophysics Data System (ADS)

Bortoli, D.; Ravegnani, F.; Giovanelli, G.; Petritoli, A.; Kostadinov, I.

GASCOD (Gas Analyzer Spectrometer Correlating Optical Differences), installed at the Italian Antarctic Station of Terra Nova Bay (TNB) - 74.69S, 164.12E - since 1995, carried out a full dataset of zenith scattered light measurements for the year 2001. The application of DOAS methodology to the collected data gave as final results, the slant column values for nitrogen dioxide. The seasonal variation shows a maxi- mum in the summer and it is in good agreement with the results obtained by other authors. The data analysis is performed by using different parameters like the po- tential vorticity (PV) at 500 K and the atmospheric temperatures at the same level. After the verification of the linear dependency between the NO2 slant column values and the temperature of NO2 cross section utilized in the DOAS algorithm, the actual stratospheric temperatures (from ECMWF) over TNB are applied to the results. The sensible changes in the nitrogen dioxide slant column values allow to highlight the good matching between the NO2 AM/PM ratio and the potential vorticity at 500 K. The NO2 slant column values follow the variations of the stratospheric temperature mainly during the spring season, when the lowest temperatures are observed and the ozone-hole phenomena mainly occur. ACKNOWLEDGMENTS: The author Daniele Bortoli was financially supported by the "Subprograma Ciência e Tecnologia do Ter- ceiro Quadro Comunitário de Apoio". The National Program for Antarctic Research (PNRA) supported this research.

Protein quality control at the inner nuclear membrane

PubMed Central

Khmelinskii, Anton; Blaszczak, Ewa; Pantazopoulou, Marina; Fischer, Bernd; Omnus, Deike J.; Le Dez, Gaëlle; Brossard, Audrey; Gunnarsson, Alexander; Barry, Joseph D.; Meurer, Matthias; Kirrmaier, Daniel; Boone, Charles; Huber, Wolfgang; Rabut, Gwenaël; Ljungdahl, Per O.; Knop, Michael

2015-01-01

The nuclear envelope is a double membrane that separates the nucleus from the cytoplasm. The inner nuclear membrane (INM) functions in essential nuclear processes including chromatin organization and regulation of gene expression1. The outer nuclear membrane is continuous with the endoplasmic reticulum (ER) and is the site of membrane protein synthesis. Protein homeostasis in this compartment is ensured by ER-associated protein degradation (ERAD) pathways that in yeast involve the integral membrane E3 ubiquitin ligases Hrd1 and Doa10 operating with the E2 ubiquitin-conjugating enzymes Ubc6 and Ubc72,3. However, little is known regarding protein quality control at the INM. Here we describe a protein degradation pathway at the INM mediated by the Asi complex consisting of the RING domain proteins Asi1 and Asi34. We report that the As complex functions together with the ubiquitin conjugating enzymes Ubc6andUbc7to degrade soluble and integral membrane proteins. Genetic evidence suggest that the Asi ubiquitin ligase defines a pathway distinct from but complementary to ERAD. Using unbiased screening with a novel genome-wide yeast library based on a tandem fluorescent protein timer (tFT)5, we identify more than 50 substrates of the Asi, Hrd1 and Doa10 E3 ubiquity ligases. We show that the Asi ubiquitin ligase is involved in degradation of mislocalised integral membrane proteins, thus acting to maintain and safeguard the identity of the INM. PMID:25519137

Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements

NASA Astrophysics Data System (ADS)

Noël, S.; Bramstedt, K.; Hilker, M.; Liebing, P.; Plieninger, J.; Reuter, M.; Rozanov, A.; Bovensmann, H.; Burrows, J. P.

2015-11-01

Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called "Onion Peeling DOAS" (ONPD) which combines an onion peeling approach with a weighting function DOAS (Differential Optical Absorption Spectroscopy) fit. By use of updated pointing information and optimisation of the data selection and of the retrieval approach the altitude range for reasonable CH4 could be extended to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5-10 % for CH4 and 2-3 % for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002-April 2012) and the latitudinal range between about 50 and 70° N have been derived. Based on these time series, CH4 and CO2 trends have been estimated, which are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere.

Identification of actinomycetes from plant rhizospheric soils with inhibitory activity against Colletotrichum spp., the causative agent of anthracnose disease.

PubMed

Intra, Bungonsiri; Mungsuntisuk, Isada; Nihira, Takuya; Igarashi, Yasuhiro; Panbangred, Watanalai

2011-04-01

Colletotrichum is one of the most widespread and important genus of plant pathogenic fungi worldwide. Various species of Colletotrichum are the causative agents of anthracnose disease in plants, which is a severe problem to agricultural crops particularly in Thailand. These phytopathogens are usually controlled using chemicals; however, the use of these agents can lead to environmental pollution. Potential non-chemical control strategies for anthracnose disease include the use of bacteria capable of producing anti-fungal compounds such as actinomycetes spp., that comprise a large group of filamentous, Gram positive bacteria from soil. The aim of this study was to isolate actinomycetes capable of inhibiting the growth of Colletotrichum spp, and to analyze the diversity of actinomycetes from plant rhizospheric soil. A total of 304 actinomycetes were isolated and tested for their inhibitory activity against Colletotrichum gloeosporioides strains DoA d0762 and DoA c1060 and Colletotrichum capsici strain DoA c1511 which cause anthracnose disease as well as the non-pathogenic Saccharomyces cerevisiae strain IFO 10217. Most isolates (222 out of 304, 73.0%) were active against at least one indicator fungus or yeast. Fifty four (17.8%) were active against three anthracnose fungi and 17 (5.6%) could inhibit the growth of all three fungi and S. cerevisiae used in the test. Detailed analysis on 30 selected isolates from an orchard at Chanthaburi using the comparison of 16S rRNA gene sequences revealed that most of the isolates (87%) belong to the genus Streptomyces sp., while one each belongs to Saccharopolyspora (strain SB-2) and Nocardiopsis (strain CM-2) and two to Nocardia (strains BP-3 and LK-1). Strains LC-1, LC-4, JF-1, SC-1 and MG-1 exerted high inhibitory activity against all three anthracnose fungi and yeast. In addition, the organic solvent extracts prepared from these five strains inhibited conidial growth of the three indicator fungi. Preliminary analysis of crude extracts by high performance liquid chromatography (HPLC) indicated that the sample from strain JF-1 may contain a novel compound. Phylogenetic analysis revealed that this strain is closely related to Streptomyces cavurensis NRRL 2740 with 99.8% DNA homology of 16S rRNA gene (500 bp). The present study suggests that rhizospheric soil is an attractive source for the discovery of a large number of actinomycetes with activity against Colletotrichum spp. An interesting strain (JF-1) with high inhibitory activity has the potential to produce a new compound that may be useful in the control of Colletotrichum spp.

First data on the volatile fluxes from passively degassing volcanoes of the Kuril Island arc

NASA Astrophysics Data System (ADS)

Melnikov, Dmitry; Malik, Nataliya; Chaplygin, Ilya; Zelenski, Mikhail

2017-04-01

We report the first data on the volatile fluxes from passively degassing volcanoes of Kuril Island arc in the North-Western Pacific measured in 2015-2016. Four volcanoes: Ebeko on the northern Paramushir Island, Kuntomintar and Pallace on the Central Shiashkotan and Ketoy islands, and Kudryavy on the southern Iturup island are representative for the whole Kuril arc as having the largest and strongest fumarolic fields among 40 of the active volcanoes of the arc. The fluxes were measured using scanning DOAS, remote miniDOAS, plume MultiGas and direct sampling techniques using the SO2 flux from the DOAS data and ratios measured by MultiGas (SO2/CO2, SO2/H2S, SO2/H2O) and direct sampling (SO2/HCl). For Kudryavy volcano the ratios were applied that have been measured by Taran et al. (1995) and Fischer et al. (1998) using direct sampling. Until now, for Kuril arc only the SO2 flux from Kudryavy was measured by the COSPEC technique in 1995 by Fischer et al. (1998) with an average SO2 flux of 75 t/d. Our data give for Kudryavy in October 2016 a value of 340 t/d. The total measured SO2 flux in 2015-2016 from the passively degassing volcanoes of the Kuril arc is near 1000 t/d. This value is an excellent agreement with the estimation made in Taran (2009) using a comparative plume height technique based on visual observations. Averaged fluxes (in ton/day) of mayor (Range of vent temperatures °C, SO2, CO2, H2O, HCl, total flux) components of volcanic emissions from Kurilian volcanoes in 2016: Ebeko - 97-490 °C, 100 (SO2), 81 (CO2), 1120 (H2O), 17 (HCl), 1319; Kuntomintar - 130-260 °C, 54 (SO2), 157 (CO2), 1064 (H2O), 8 (HCl), 1283; Pallas - 140-720 °C, 450 (SO2), 78 (CO2), 3800 (H2O), 120 (HCl), 4448; Kudryavy - 130-920 °C, 340 (SO2), 131 (CO2), 4445 (H2O), 85 (HCl), 5001. Total (± 20%): 930 (SO2), 450 (CO2), 10400 (H2O), 230 (HCl), 12050 (total flux). This work was supported by grant from the Russian Science Foundation # 15-17-20011. References: Taran et al. (1995) GCA, 59, 1741-1761; Fischer et al. (1998) EPSL, 160, 81-96; Taran (2009) GCA, 73, 1067-1091

Global observations of glyoxal columns from OMI/Aura and GOME-2/Metop-A sensors and comparison with multi-year simulations by the IMAGES model

NASA Astrophysics Data System (ADS)

Lerot, Christophe; Stavrakou, Trissevgeni; Hendrick, François; De Smedt, Isabelle; Müller, Jean-François; Volkamer, Rainer; Van Roozendael, Michel

2015-04-01

Volatile organic compounds (VOCs) originating from both natural and human activities play a key role in air quality. Information on their atmospheric concentrations can be derived using remote sensing techniques for a limited number of species, including formaldehyde (HCHO) and glyoxal (CHOCHO). The latter is mostly produced in the atmosphere as an intermediate product in the oxidation of other non-methane VOCs. It is also directly emitted from fire events and combustion processes. Owing to its short lifetime, elevated glyoxal concentrations are observed near emission sources. Measurements of atmospheric glyoxal concentrations therefore provide quantitative information on the different types of VOC emission and can help to better assess the quality of current inventories. In addition, glyoxal is also known to significantly contribute to the total budget of secondary organic aerosols. Global observations of glyoxal columns have been realized from different space-borne spectrometers using the well-known DOAS retrieval technique. In the past, we developed an algorithm to retrieve glyoxal columns from spectra measured by the GOME-2 instrument aboard METOP-A (Lerot et al., 2010). Specificities of this algorithm were an original two-step approach in the DOAS fit to minimize the impact of spectral interferences with the liquid water absorption as well as the use of a priori information from the Chemical Transport Model IMAGES in the air mass factor calculation. In this work, we present the adaptation of this algorithm to the OMI sensor on the AURA platform. The time series of glyoxal columns derived from OMI and GOME-2 are compared in different parts of the world and a high level of consistency is found. The OMI glyoxal data product is found to be very stable over the entire duration of the mission, in contrast to the GOME-2 product which is affected by instrumental degradation. We present validation results using several years of MAX-DOAS glyoxal measurements successively performed in Beijing and Xianghe, China, since 2008. Also, comparisons of the satellite data sets with simulations by the IMAGES chemistry transport model show generally good correlation. Sensitivity tests on the VOC emissions used in the model will also be discussed. Lerot, C., Stavrakou, T., De Smedt, I., Müller, J.-F., and Van Roozendael, M.: Glyoxal vertical columns from GOME-2 backscattered light measurements and comparisons with a global model, Atmos. Chem. Phys., 10, 12059-12072, doi:10.5194/acp-10-12059-2010, 2010.

Histologic Changes Caused by Application of Lewisite Analogs to Mouse Skin and Human Skin Xenografts

DTIC Science & Technology

1985-01-01

CLASSIICATION OF THIS PAGE (Nh..1 DO&a Eatat1d UNCLAS8inED S6CURmTV CLASSISCATION OP THIS PA•r(em Daf EMo* skin grafts : 1) epidermal cellular nuclear...microscopy. Under light microscopy, we observed the following changes In PDA-treated human skin grafts : I) epidermal cellular nuclear degeneration (apparent...needed. (Oe such model is ti-e human skin grafted athymic nude mouse (4,5). This animal model was recently established at LAIR. PhenyLdichLoroarsine (PDA

Impacts of Spatial Fidelity Violations in the Forward Signal Model on DOAS-based Greenhouse Gas Retrievals: a Preliminary Analysis for OCO-2 (and Other Missions)

NASA Technical Reports Server (NTRS)

Davis, Anthony B.; Frakenbert, Christian

2012-01-01

Success in three aspects of OCO-2 mission is threatened by unaccounted spa,al variability effects, all involving atmospheric scattering: 1. Low/moderately opaque clouds can escape the prescreening by mimicking a brighter surface. 2. Prescreening does not account for long-range radia,ve impact (adjacency effect) of nearby clouds. Need for extended cloud masking? 3. Oblique looks in target mode are highly exposed to surface adjacency and aerosol variability effects.We'll be covering all three bases!

Proposed Barge Terminal Expansion, Packer River Terminal, Inc., South St. Paul, Dakota County, Minnesota.

DTIC Science & Technology

1977-09-01

On 24 June 1974 Packer applied to the St. Paul District, Corps of Engineers (Corps) for a DOA permit under Section 10 of the River and Harbor Act of...exercised jurisdiction under Section 404 of P.L. 92-500 to the ordinary high water mark of the • Mississippi River, Thu’, even though the proposed project...Corps of Engineers was to expand their regulatory IT ril ct ion under Sect ion 404 of P.l.. 92-500 ,nd to promulgate new r- ’~giiI.,t .; ill conjunct

A new DOD and DOA estimation method for MIMO radar

NASA Astrophysics Data System (ADS)

Gong, Jian; Lou, Shuntian; Guo, Yiduo

2018-04-01

The battlefield electromagnetic environment is becoming more and more complex, and MIMO radar will inevitably be affected by coherent and non-stationary noise. To solve this problem, an angle estimation method based on oblique projection operator and Teoplitz matrix reconstruction is proposed. Through the reconstruction of Toeplitz, nonstationary noise is transformed into Gauss white noise, and then the oblique projection operator is used to separate independent and correlated sources. Finally, simulations are carried out to verify the performance of the proposed algorithm in terms of angle estimation performance and source overload.

Technical Papers Presented at the Defense Nuclear Agency Global Effects Review. Held at Moffett Field, California on 25-27 February 1986. Volume 1.

DTIC Science & Technology

1986-05-15

0.4 -4 -4.4 >1 -1 1% ~~~ 404EDCE doa- -4 -4 -45 ti ahEEED U.,~ U2. 44d 0 00.) ) 41 to0 4 V AJJV a09 00 go W Ac AC ACca .04J0.0 .0WhO >J413W...SCIENCES CORP ATTN MAJ GEN HJCOATES ATTN: M KAPLAN ATTN P PROSSER TECHNOLOGY INTERNATIONAL CORP BRITISH DEFENCE STAFF ""ATTN. W BOQUIST ATTN C FENWICK

Intercomparison of field measurements of nitrous acid (HONO) during the SHARP campaign

NASA Astrophysics Data System (ADS)

Pinto, J. P.; Dibb, J.; Lee, B. H.; Rappenglück, B.; Wood, E. C.; Levy, M.; Zhang, R.-Y.; Lefer, B.; Ren, X.-R.; Stutz, J.; Tsai, C.; Ackermann, L.; Golovko, J.; Herndon, S. C.; Oakes, M.; Meng, Q.-Y.; Munger, J. W.; Zahniser, M.; Zheng, J.

2014-05-01

Because of the importance of HONO as a radical reservoir, consistent and accurate measurements of its concentration are needed. As part of SHARP (Study of Houston Atmospheric Radical Precursors), time series of HONO were obtained by six different measurement techniques on the roof of the Moody Tower at the University of Houston. Techniques used were long path differential optical absorption spectroscopy (DOAS), stripping coil-visible absorption photometry (SC-AP), long path absorption photometry (LOPAP®), mist chamber/ion chromatography (MC-IC), quantum cascade-tunable infrared laser differential absorption spectroscopy (QC-TILDAS), and ion drift-chemical ionization mass spectrometry (ID-CIMS). Various combinations of techniques were in operation from 15 April through 31 May 2009. All instruments recorded a similar diurnal pattern of HONO concentrations with higher median and mean values during the night than during the day. Highest values were observed in the final 2 weeks of the campaign. Inlets for the MC-IC, SC-AP, and QC-TILDAS were collocated and agreed most closely with each other based on several measures. Largest differences between pairs of measurements were evident during the day for concentrations < 100 parts per trillion (ppt). Above 200 ppt, concentrations from the SC-AP, MC-IC, and QC-TILDAS converged to within about 20%, with slightly larger discrepancies when DOAS was considered. During the first 2 weeks, HONO measured by ID-CIMS agreed with these techniques, but ID-CIMS reported higher values during the afternoon and evening of the final 4 weeks, possibly from interference from unknown sources. A number of factors, including building related sources, likely affected measured concentrations.

Is a scaling factor required to obtain closure between measured and modelled O4 absorptions? - A case study for two days during the MADCAT campaign

NASA Astrophysics Data System (ADS)

Wagner, Thomas

2017-04-01

Measurements of the oxygen dimer O4 are often used in remote sensing applications to infer information on the atmospheric light path distribution. Such information is interesting in itself, but can also be used to retrieve properties of clouds and aerosols, e.g. from ground based Multi-AXis-Differential Optical Absorption Spectroscopy (MAX-DOAS) observations. In recent years, a scaling factor (between about 0.7 and 1) was applied by several groups to the retrieved O4 slant column densities in order to obtain meaningful aerosol profiles from MAX-DOAS observations. However, other groups did not report the need for such a scaling factor. Up to now, this discrepancy is neither understood nor resolved. Here we compare measured and modelled O4 slant column densities for two days during the MADCAT campaign (http://joseba.mpch-mainz.mpg.de/mad_cat.htm). Clouds were mostly absent during both days, and the aerosol profiles are constrained by simultaneous sun photometer and ceilometer measurements. One important difference between both days is the amount of aerosol in the lowest atmospheric layer. Our comparison study addresses several important steps of the O4 data analysis, such as the spectral retrieval and the radiative transfer simulations. We also investigate the effects of temperature and pressure variations on the calculation of the O4 vertical column density. Preliminary results are are not conclusive but indicate that a scaling factor is needed to bring measurements and simulations into agreement at least for one of the two selected days.

OMI satellite observed formaldehyde column from 2006 to 2015 over Xishuangbanna, southwest China, and validation using ground based zenith-sky DOAS.

PubMed

Liu, Rui; Feng, Tao; Wang, Shanshan; Shi, Chanzhen; Guo, Yanlin; Nan, Jialiang; Deng, Yun; Zhou, Bin

2018-02-01

Formaldehyde (HCHO) provides a proxy to reveal the isoprene and biogenic volatile organic compounds emission which plays important roles in atmospheric chemical process and climate change. The ground-based observation with zenith-sky DOAS is carried out in order to validate the HCHO columns from OMI. It has a good correlation of 0.71678 between the HCHO columns from two sources. Then we use the OMI HCHO columns from January 2006 to December 2015 to indicate the interannual variation and spatial distribution in Xishuangbanna. The HCHO concentration peaks appeared in March or April for each year significantly corresponding to the intensive fire counts at the same time, which illustrate that the high HCHO columns are strongly influenced by the biomass burning in spring. Temperature and precipitation are also the important influence factors in the seasonal variation when there is nearly no biomass burning. The spatial patterns over the past ten years strengthen the deduction from the temporal variation and show the relationship with land cover and land use, elevation and population density. It is concluded that the biogenic activity plays a role in controlling the background level of HCHO in Xishuangbanna, while biomass burning is the main driving force of high HCHO concentration. And forests are greater contributor to HCHO rather than rubber trees which cover over 20% of the land in the region. Moreover, uncertainties from HCHO slant column retrieval and AMFs calculation are discussed in detail. Copyright © 2017. Published by Elsevier B.V.

Observations of iodine monoxide in the Arctic troposphere

NASA Astrophysics Data System (ADS)

Zielcke, Johannes; Lampel, Johannes; Frieß, Udo; Sihler, Holger; Netcheva, Stoyka; Platt, Ulrich

2014-05-01

A unique feature of the polar troposphere is the strong impact of halogen photochemistry, in which reactive halogen species are responsible for ozone depletion as well as the oxidation of elemental mercury and dimethyl sulfide. The sources, however, as well as release and recycling mechanisms of these halogen species are far from being completely understood, especially the role of chlorine and iodine compounds. For iodine, which is thought to be produced either by organic precursors or inorganic processes, one curious issue is the difference of its role in the two polar regions, the Arctic and the Antarctic. Satellite observations show significant quantities of IO in large areas of Antarctica and the surrounding ocean and comparatively no IO in the Arctic. This is in concordance with some ground-based remote sensing observations in Antarctica, whereas publications of IO mixing ratios or upper limits from the Arctic are seldom. This strong hemispheric dichotomy may however not be the whole picture. Here we present data from ground-based MAX-DOAS observations in the Arctic. Long-term measurements from Alert, Canada (82N) spanning the period from 2007 until 2013 indicate elevated and significant quantities of IO in the troposphere in late spring and early summer comparable to ground-based observations in Antarctica. This is backed up by ship-borne MAX-DOAS measurements in Baffin Bay during summer 2010, which also show elevated and significant amounts of IO. Furthermore the interaction of IO and BrO will be shown, as well as the influence of meteorological parameters and the data will be compared to other measurements.

Evaluation of emissions from simulated commercial meat wrapping operations using PVC wrap.

PubMed

Smith, T J; Cafarella, J J; Chelton, C; Crowley, S

1983-03-01

Meatwrapper's asthma is an elusive health problem with a suspected relationship to exposure to emissions from polyvinyl chloride (PVC) film cut with a hot wire. A study was conducted to determine how the type of wrap cutter (wire or rod) and its temperature affected the emissions from a simulated occupational wrapping process. The cutting temperatures covered the same range as was measured in Boston retail food stores. A commercial wrapping machine and samples of commercial PVC meat and produce wraps were used. Seventy five percent of the particulate from the hot wire was respirable, and the quantity of emissions was a strong function of the film tension and cutting technique. Particulate emissions did not increase steadily with increasing wire temperature, but plateaued or declined at high temperatures. Particulate emissions from the rod cutter were very low at low temperatures, but exceeded those of the wire at temperatures above 200 degrees C. The particulate was 100% dioctyl adipate (DOA, the plasticizer in the wrap) with wire temperatures below 200 degrees C, and was approximately 80% DOA for temperatures above this. Gaseous HCl was not detected in emissions from a hot wire operated below 150 degrees C, but HCl emissions increased rapidly to a plateau for temperatures above 200 degrees C. Approximately 20% of the HCl produced at temperatures above 200 degrees C was associated with the particulate, which appeared to act as a carrier and transport the HCl through water filled impingers. Field tests are needed to determine if particulate produced in the workplace may also behave as a carrier for HCl.

Improving the accuracy of S02 column densities and emission rates obtained from upward-looking UV-spectroscopic measurements of volcanic plumes by taking realistic radiative transfer into account

USGS Publications Warehouse

Kern, Christoph; Deutschmann, Tim; Werner, Cynthia; Sutton, A. Jeff; Elias, Tamar; Kelly, Peter J.

2012-01-01

Sulfur dioxide (SO2) is monitored using ultraviolet (UV) absorption spectroscopy at numerous volcanoes around the world due to its importance as a measure of volcanic activity and a tracer for other gaseous species. Recent studies have shown that failure to take realistic radiative transfer into account during the spectral retrieval of the collected data often leads to large errors in the calculated emission rates. Here, the framework for a new evaluation method which couples a radiative transfer model to the spectral retrieval is described. In it, absorption spectra are simulated, and atmospheric parameters are iteratively updated in the model until a best match to the measurement data is achieved. The evaluation algorithm is applied to two example Differential Optical Absorption Spectroscopy (DOAS) measurements conducted at Kilauea volcano (Hawaii). The resulting emission rates were 20 and 90% higher than those obtained with a conventional DOAS retrieval performed between 305 and 315 nm, respectively, depending on the different SO2 and aerosol loads present in the volcanic plume. The internal consistency of the method was validated by measuring and modeling SO2 absorption features in a separate wavelength region around 375 nm and comparing the results. Although additional information about the measurement geometry and atmospheric conditions is needed in addition to the acquired spectral data, this method for the first time provides a means of taking realistic three-dimensional radiative transfer into account when analyzing UV-spectral absorption measurements of volcanic SO2 plumes.

The New MAX-DOAS Network in Mexico City for Trace Gas Detection

NASA Astrophysics Data System (ADS)

Arellano, E. J.; Krüger, A.; Rivera, C. I.; Stremme, W.; Friedrich, M. M.; Grutter, M.

2014-12-01

Atmospheric studies in large cities are of great relevance since pollution affects air quality and human health. We have designed and built instruments based on the Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) technique and established a network in strategic sites within the Mexico City metropolitan area. Four instruments are now in operation with the aim to study the variability and spatial distribution of key pollutants, which will bring new insight in the current knowledge of transport patterns, emissions as well as frequency and origin of extraordinary events. The instruments measure UV/visible spectra of the sky at different elevation angles in the 280 nm to 510 nm wavelength region along one axis. Currently, 36 measurements constitute a full scan performed from west until East direction (-90 to +90°). The scanning unit, which is installed outdoors, holds a small telescope and the motor control unit. Light is transmitted via an optical fiber to the main box, which holds a compact USB spectrometer and the main control electronics. The spectrometer is accurately temperature controlled and all the spectra of each scan, together with elevation angle and other parameters, are recorded on a compact PC. Post processing of these data with the QDOAS software results in slant column densities (SCD) of the atmospheric gases. This information is then converted to vertical profiles through a process described in a companion presentation. Preliminary results will be presented for formaldehyde, fitted in the region 324-360 nm. The data obtained is useful for the comparison with satellite data for example OMI.

Performance evaluation of radiant cooling system integrated with air system under different operational strategies

DOE PAGES

Khan, Yasin; Khare, Vaibhav Rai; Mathur, Jyotirmay; ...

2015-03-26

The paper describes a parametric study developed to estimate the energy savings potential of a radiant cooling system installed in a commercial building in India. The study is based on numerical modeling of a radiant cooling system installed in an Information Technology (IT) office building sited in the composite climate of Hyderabad. To evaluate thermal performance and energy consumption, simulations were carried out using the ANSYS FLUENT and EnergyPlus softwares, respectively. The building model was calibrated using the measured data for the installed radiant system. Then this calibrated model was used to simulate the energy consumption of a building usingmore » a conventional all-air system to determine the proportional energy savings. For proper handling of the latent load, a dedicated outside air system (DOAS) was used as an alternative to Fan Coil Unit (FCU). A comparison of energy consumption calculated that the radiant system was 17.5 % more efficient than a conventional all-air system and that a 30% savings was achieved by using a DOAS system compared with a conventional system. Computational Fluid Dynamics (CFD) simulation was performed to evaluate indoor air quality and thermal comfort. It was found that a radiant system offers more uniform temperatures, as well as a better mean air temperature range, than a conventional system. To further enhance the energy savings in the radiant system, different operational strategies were analyzed based on thermal analysis using EnergyPlus. Lastly, the energy savings achieved in this parametric run were more than 10% compared with a conventional all-air system.« less

Aircraft in situ and remote sensing measurements of emissions from Etna volcano, Sicily

NASA Astrophysics Data System (ADS)

Vogel, A.; Weber, K.; Fischer, C.; Prata, A. J.; Durant, A. J.

2012-04-01

Volcanoes emit particles (silicates and sulphate aerosol) and gases (e.g., water and sulphur dioxide) which influence the radiative balance of the atmosphere. The rate at which sulphur dioxide oxidises to sulphate aerosol is poorly constrained and measurements of downwind abundance are required to quantify the rate at which this process occurs. During July and November 2011, a series of measurements were performed in emissions from Etna Volcano, Sicily, using the University of Applied Sciences (Dusseldorf) research aircraft. Both in situ and remote sensing instrumentation was simultaneously deployed to quantify the down-wind characteristics of gases and particles in the plume emitted by the volcano. In situ particle characteristics were measured using a Grimm 1.109 optical particle counter (microparticles 0.25-32 microns) and Grimm 1320 diffusion electrometer (nanoparticles 25-300 nanometers). Column abundance of sulphur dioxide was measured using a vertically-pointing differential optical absorption spectrometer (DOAS). These measurements were compared to horizontal pathlength-integrated measurements of sulphur dioxide from the Airborne Volcanic Imaging Object Detector (AVOID). Down-wind plume dispersion was discriminated through a series of aircraft transects below and through the volcanic plume. The emissions contained large amounts of nanoparticles relative to microparticles, which reflects gas-phase nucleation of sulphate aerosol. The AVOID system discriminated horizontal layering of volcanic aerosol at altitudes of up to 12,000 ft from a detection range of >50 km. Plume boundaries were discriminated using a combination of the in situ and DOAS measurements in order to compare to the pathlength-integrated measurements from AVOID.

Proteolytic regulation of metabolic enzymes by E3 ubiquitin ligase complexes: lessons from yeast.

PubMed

Nakatsukasa, Kunio; Okumura, Fumihiko; Kamura, Takumi

2015-01-01

Eukaryotic organisms use diverse mechanisms to control metabolic rates in response to changes in the internal and/or external environment. Fine metabolic control is a highly responsive, energy-saving process that is mediated by allosteric inhibition/activation and/or reversible modification of preexisting metabolic enzymes. In contrast, coarse metabolic control is a relatively long-term and expensive process that involves modulating the level of metabolic enzymes. Coarse metabolic control can be achieved through the degradation of metabolic enzymes by the ubiquitin-proteasome system (UPS), in which substrates are specifically ubiquitinated by an E3 ubiquitin ligase and targeted for proteasomal degradation. Here, we review select multi-protein E3 ligase complexes that directly regulate metabolic enzymes in Saccharomyces cerevisiae. The first part of the review focuses on the endoplasmic reticulum (ER) membrane-associated Hrd1 and Doa10 E3 ligase complexes. In addition to their primary roles in the ER-associated degradation pathway that eliminates misfolded proteins, recent quantitative proteomic analyses identified native substrates of Hrd1 and Doa10 in the sterol synthesis pathway. The second part focuses on the SCF (Skp1-Cul1-F-box protein) complex, an abundant prototypical multi-protein E3 ligase complex. While the best-known roles of the SCF complex are in the regulation of the cell cycle and transcription, accumulating evidence indicates that the SCF complex also modulates carbon metabolism pathways. The increasing number of metabolic enzymes whose stability is directly regulated by the UPS underscores the importance of the proteolytic regulation of metabolic processes for the acclimation of cells to environmental changes.

Bromine, chlorine and sulfur emission into the free troposphere from a Rift volcano

NASA Astrophysics Data System (ADS)

Bobrowski, N.; Giuffrida, G. B.; Tedeso, D.; Yalire, M. M.; Galle, B.

2007-12-01

In June 2007 spectroscopic measurements were carried out at the crater rim of the Niyragongo volcano located 15 km north of the city Goma, North Kivu region (DRC). Niyragongo volcano belongs to the Virunga volcanic chain and it is associated with the Western branch of the Great Rift Valley. The volcanism at Niyragongo is caused by the rifting of the Earth's crust where two parts of the African plates are breaking apart. Niyragongo is a 3470 m high stratovolcano, which a large summit crater usually containing a lava lake inside and it is considered one of the most active volcanoes in Africa. Satellite measurements show an extremely large sulphur dioxide plume since May 2002, and it is considered one of the biggest sulphur dioxide sources on Earth. The ground - based remote sensing technique - MAX-DOAS (Multi Axis Differential Optical Absorption Spectroscopy) using scattered sunlight has been applied during a one week field trip on top of the crater rim of Niyragongo volcano to measure nitrogen oxide, halogen oxides and sulphur dioxide. The used Mini-MAX-DOAS is a lightweight, compact, robust instrument and has very low power consumption which allows to be deployed over several days with some small lead batteries. The measurements provide valuable information of the chemical composition as well its variability within the volcanic plume of the lava lake and allowed also studying chemical transformation processes of the halogens inside the plume. Bromine-sulphur and chlorine-sulphur ratios were investigated and a minimal bromine and chlorine emission flux estimation will be presented.

Penetration of Face Hardened Bullet Proof Steel by Yawed .50 cal. AP (armor Piercing) Bullets at O deg. Obliquity

DTIC Science & Technology

1943-07-09

for sevarad platos a o"’l i~u.Li * DAVID I. 157"iCYI, Copy, tos 81*,AI’C Doa ’* (dir*et) B3uiad Deec !’Alb (diroot) Lt, Gseauque 10 tJt. Jolmson- E...2233 10 CP N1 1/21’ Hole. 42 2265 55 PP NH 2" Pin S. 43 2260 53 PP NH 3" x 4" Crack. 44 2240 25 PP RJ HB No Crack. 45 2252 27 PP RJ RB No Cracks, 46

When Should You Terminate Your Own Program? Bad Business: The JASORS Debacle

DTIC Science & Technology

2005-11-30

NPS-PM-06-002= Wh ^Åèì do^a k^s^^`nrfpfqflk=oÉëÉ~êÅÜ tçêâáåÖ=é~éÉê=pÉêáÉë= = en Should You Terminate Your Own Program? Bad Business : The...JASORS Debacle 30 November 2005 by John T. Dillard, Senior Lecturer Graduate School of Business & Public Policy Approved for public release...Own Program? Bad Business : The JASORS Debacle 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e

Closed-Form 3-D Localization for Single Source in Uniform Circular Array with a Center Sensor

NASA Astrophysics Data System (ADS)

Bae, Eun-Hyon; Lee, Kyun-Kyung

A novel closed-form algorithm is presented for estimating the 3-D location (azimuth angle, elevation angle, and range) of a single source in a uniform circular array (UCA) with a center sensor. Based on the centrosymmetry of the UCA and noncircularity of the source, the proposed algorithm decouples and estimates the 2-D direction of arrival (DOA), i.e. azimuth and elevation angles, and then estimates the range of the source. Notwithstanding a low computational complexity, the proposed algorithm provides an estimation performance close to that of the benchmark estimator 3-D MUSIC.

Multisource passive acoustic tracking: an application of random finite set data fusion

NASA Astrophysics Data System (ADS)

Ali, Andreas M.; Hudson, Ralph E.; Lorenzelli, Flavio; Yao, Kung

2010-04-01

Multisource passive acoustic tracking is useful in animal bio-behavioral study by replacing or enhancing human involvement during and after field data collection. Multiple simultaneous vocalizations are a common occurrence in a forest or a jungle, where many species are encountered. Given a set of nodes that are capable of producing multiple direction-of-arrivals (DOAs), such data needs to be combined into meaningful estimates. Random Finite Set provides the mathematical probabilistic model, which is suitable for analysis and optimal estimation algorithm synthesis. Then the proposed algorithm has been verified using a simulation and a controlled test experiment.

Identification of actinomycetes from plant rhizospheric soils with inhibitory activity against Colletotrichum spp., the causative agent of anthracnose disease

PubMed Central

2011-01-01

Background Colletotrichum is one of the most widespread and important genus of plant pathogenic fungi worldwide. Various species of Colletotrichum are the causative agents of anthracnose disease in plants, which is a severe problem to agricultural crops particularly in Thailand. These phytopathogens are usually controlled using chemicals; however, the use of these agents can lead to environmental pollution. Potential non-chemical control strategies for anthracnose disease include the use of bacteria capable of producing anti-fungal compounds such as actinomycetes spp., that comprise a large group of filamentous, Gram positive bacteria from soil. The aim of this study was to isolate actinomycetes capable of inhibiting the growth of Colletotrichum spp, and to analyze the diversity of actinomycetes from plant rhizospheric soil. Results A total of 304 actinomycetes were isolated and tested for their inhibitory activity against Colletotrichum gloeosporioides strains DoA d0762 and DoA c1060 and Colletotrichum capsici strain DoA c1511 which cause anthracnose disease as well as the non-pathogenic Saccharomyces cerevisiae strain IFO 10217. Most isolates (222 out of 304, 73.0%) were active against at least one indicator fungus or yeast. Fifty four (17.8%) were active against three anthracnose fungi and 17 (5.6%) could inhibit the growth of all three fungi and S. cerevisiae used in the test. Detailed analysis on 30 selected isolates from an orchard at Chanthaburi using the comparison of 16S rRNA gene sequences revealed that most of the isolates (87%) belong to the genus Streptomyces sp., while one each belongs to Saccharopolyspora (strain SB-2) and Nocardiopsis (strain CM-2) and two to Nocardia (strains BP-3 and LK-1). Strains LC-1, LC-4, JF-1, SC-1 and MG-1 exerted high inhibitory activity against all three anthracnose fungi and yeast. In addition, the organic solvent extracts prepared from these five strains inhibited conidial growth of the three indicator fungi. Preliminary analysis of crude extracts by high performance liquid chromatography (HPLC) indicated that the sample from strain JF-1 may contain a novel compound. Phylogenetic analysis revealed that this strain is closely related to Streptomyces cavurensis NRRL 2740 with 99.8% DNA homology of 16S rRNA gene (500 bp). Conclusion The present study suggests that rhizospheric soil is an attractive source for the discovery of a large number of actinomycetes with activity against Colletotrichum spp. An interesting strain (JF-1) with high inhibitory activity has the potential to produce a new compound that may be useful in the control of Colletotrichum spp. PMID:21457542

The Greenhouse Gas Climate Change Initiative (GHG-CCI): comparative validation of GHG-CCI SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT CO2 and CH4 retrieval algorithm products with measurements from the TCCON

NASA Astrophysics Data System (ADS)

Dils, B.; Buchwitz, M.; Reuter, M.; Schneising, O.; Boesch, H.; Parker, R.; Guerlet, S.; Aben, I.; Blumenstock, T.; Burrows, J. P.; Butz, A.; Deutscher, N. M.; Frankenberg, C.; Hase, F.; Hasekamp, O. P.; Heymann, J.; De Mazière, M.; Notholt, J.; Sussmann, R.; Warneke, T.; Griffith, D.; Sherlock, V.; Wunch, D.

2014-06-01

Column-averaged dry-air mole fractions of carbon dioxide and methane have been retrieved from spectra acquired by the TANSO-FTS (Thermal And Near-infrared Sensor for carbon Observations-Fourier Transform Spectrometer) and SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography) instruments on board GOSAT (Greenhouse gases Observing SATellite) and ENVISAT (ENVIronmental SATellite), respectively, using a range of European retrieval algorithms. These retrievals have been compared with data from ground-based high-resolution Fourier transform spectrometers (FTSs) from the Total Carbon Column Observing Network (TCCON). The participating algorithms are the weighting function modified differential optical absorption spectroscopy (DOAS) algorithm (WFMD, University of Bremen), the Bremen optimal estimation DOAS algorithm (BESD, University of Bremen), the iterative maximum a posteriori DOAS (IMAP, Jet Propulsion Laboratory (JPL) and Netherlands Institute for Space Research algorithm (SRON)), the proxy and full-physics versions of SRON's RemoTeC algorithm (SRPR and SRFP, respectively) and the proxy and full-physics versions of the University of Leicester's adaptation of the OCO (Orbiting Carbon Observatory) algorithm (OCPR and OCFP, respectively). The goal of this algorithm inter-comparison was to identify strengths and weaknesses of the various so-called round- robin data sets generated with the various algorithms so as to determine which of the competing algorithms would proceed to the next round of the European Space Agency's (ESA) Greenhouse Gas Climate Change Initiative (GHG-CCI) project, which is the generation of the so-called Climate Research Data Package (CRDP), which is the first version of the Essential Climate Variable (ECV) "greenhouse gases" (GHGs). For XCO2, all algorithms reach the precision requirements for inverse modelling (< 8 ppm), with only WFMD having a lower precision (4.7 ppm) than the other algorithm products (2.4-2.5 ppm). When looking at the seasonal relative accuracy (SRA, variability of the bias in space and time), none of the algorithms have reached the demanding < 0.5 ppm threshold. For XCH4, the precision for both SCIAMACHY products (50.2 ppb for IMAP and 76.4 ppb for WFMD) fails to meet the < 34 ppb threshold for inverse modelling, but note that this work focusses on the period after the 2005 SCIAMACHY detector degradation. The GOSAT XCH4 precision ranges between 18.1 and 14.0 ppb. Looking at the SRA, all GOSAT algorithm products reach the < 10 ppm threshold (values ranging between 5.4 and 6.2 ppb). For SCIAMACHY, IMAP and WFMD have a SRA of 17.2 and 10.5 ppb, respectively.

NOVAC - Network for Observation of Volcanic and Atmospheric Change: Data archiving and management

NASA Astrophysics Data System (ADS)

Lehmann, T.; Kern, C.; Vogel, L.; Platt, U.; Johansson, M.; Galle, B.

2009-12-01

The potential for volcanic risk assessment using real-time gas emissions data and the recognized power of sharing data from multiple eruptive centers were the motivation for a European Union FP6 Research Program project entitled NOVAC: Network for Observation of Volcanic and Atmospheric Change. Starting in 2005, a worldwide network of permanent scanning Differential Optical Absorption Spectroscopy (DOAS) instruments was installed at 26 volcanoes around the world. These ground-based remote sensing instruments record the characteristic absorption of volcanic gas emissions (e.g. SO2, BrO) in the ultra-violet wavelength region. A real-time DOAS retrieval was implemented to evaluate the measured spectra, thus providing the respective observatories with gas emission data which can be used for volcanic risk assessment and hazard prediction. Observatory personnel at each partner institution were trained on technical and scientific aspects of the DOAS technique, and a central database was created to allow the exchange of data and ideas between all partners. A bilateral benefit for volcano observatories as well as scientific institutions (e.g. universities and research centers) resulted. Volcano observatories were provided with leading edge technology for measuring volcanic SO2 emission fluxes, and now use this technology for monitoring and risk assessment, while the involved universities and research centers are working on global studies and characterizing the atmospheric impact of the observed gas emissions. The NOVAC database takes into account that project members use the database in a variety of different ways. Therefore, the data is structured in layers, the top of which contains basic information about each instrument. The second layer contains evaluated emission data such as SO2 column densities, SO2 emission fluxes, and BrO/SO2 ratios. The lowest layer contains all spectra measured by the individual instruments. Online since the middle of 2006, the NOVAC database currently contains 26 volcanoes, 56 instruments and more than 50 million spectra. It is scalable for up to 200 or more volcanoes, as the NOVAC project is open to outside participation. The data is archived in a MySQL Database system, storing and querying is done with PHP functions. The web interface is dynamically created based on the existing dataset and offers approx. 150 different search, display, and sorting options. Each user has a separate account and can save his personal search configuration from session to session. Search results are displayed in table form and can also be downloaded. Both evaluated data files and measured spectra can be downloaded as single files or in packages. The spectra can be plotted directly from the database, as well as several measurement values and evaluated parameters over selectable timescales. Because of the large extent of the dataset, major emphasis was placed on performance optimization.

Long-Term Monitoring Research Needs: A DOE Perspective

NASA Astrophysics Data System (ADS)

Moore, B.; Davis, C. B.

2002-05-01

The U.S. Department of Energy's Office of Environmental Management is responsible for dealing with the nation's legacy of Cold War radioactive and hazardous waste and contamination. Major efforts are underway to deal with this legacy; these are expected to last up to decades and cost up to billions of dollars at some sites. At all sites, however, active remediation must eventually cease; if hazards then remain, the site must enter into a long-term stewardship mode. In this talk we discuss aspects of long-term monitoring pertinent to DOE sites, focusing on challenges to be faced, specific goals or targets to be met, and research needs to be addressed in order to enable DOE to meet its long-term stewardship obligations. DOE LTM research needs fall into three major categories: doing what we can do now much more efficiently; doing things we cannot do now; and proving the validity of our monitoring programs. Given the enormity of the DOE obligations, it will be highly desirable to develop much more efficient monitoring paradigms. Doing so will demand developing autonomous, remote monitoring networks of in situ sensors capable of replacing (or at least supplementing to a large extent) conventional groundwater and soil gas sampling and analysis programs. The challenges involved range from basic science (e.g., inventing in situ sensors for TCE that do not demand routine maintenance) to engineering (attaining superior reliability in data reporting in remote networks) to ergonomics (developing decent ways of selecting and presenting the "right" information from the monitoring network) to regulatory affairs (presenting convincing evidence that the more efficient systems actually provide superior monitoring). We explore these challenges in some detail, focusing on the "long" in long-term monitoring as it applies to DOE sites. Monitoring system performance validation and, ultimately, regulator and stakeholder acceptance of site closure and long-term stewardship plans depend critically on the validity and uncertainty in models used to predict contaminant fate and transport. This is an area of active research at the present time. We survey joint research initiatives in this area involving DOE along with USGS, U.S. EPA, U.S. NRC, and U.S. DOA and non-Federal collaborators, and explore their potential for furthering DOE long-term monitoring needs and objectives.

The Effects of Surface Properties and Albedo on Methane Retrievals with the Airborne Visible/Infrared Imaging Spectrometer Next Generation (AVIRIS-NG)

NASA Astrophysics Data System (ADS)

Ayasse, A.; Thorpe, A. K.; Roberts, D. A.

2017-12-01

Atmospheric methane has increased by a factor of 2.5 since the beginning of the industrial era in response to anthropogenic emissions (Ciais et al., 2013). Although it is less abundant than carbon dioxide it is 86 time more potent on a 20 year time scale (Myhre et al., 2013) and is therefore responsible for about 20% of the total global warming induced by anthropogenic greenhouse gasses (Kirschke et al., 2013). Given the importance of methane to global climate change, monitoring and measuring methane emissions using techniques such as remote sensing is of increasing interest. Recently the Airborne Visible-Infrared Imaging Spectrometer - Next Generation (AVIRIS-NG) has proven to be a valuable instrument for quantitative mapping of methane plumes (Frankenberg et al., 2016; Thorpe et al., 2016; Thompson et al., 2015). In this study, we applied the Iterative Maximum a Posterior Differential Optical Spectroscopy (IMAP-DOAS) methane retrieval algorithm to a synthetic image with variable methane concentrations, albedo, and land cover. This allowed for characterizing retrieval performance, including potential sensitivity to variable land cover, low albedo surfaces, and surfaces known to cause spurious signals. We conclude that albedo had little influence on the IMAP-DOAS results except at very low radiance levels. Water (without sun glint) was found to be the most challenging surface for methane retrievals while hydrocarbons and some green vegetation also caused error. Understanding the effect of surface properties on methane retrievals is important given the increased use of AVIRIS-NG to map gas plumes over diverse locations and methane sources. This analysis could be expanded to include additional gas species like carbon dioxide and to further investigate gas sensitivity of proposed instruments for dedicated gas mapping from airborne and spaceborne platforms.

Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG

NASA Astrophysics Data System (ADS)

Thorpe, Andrew K.; Frankenberg, Christian; Thompson, David R.; Duren, Riley M.; Aubrey, Andrew D.; Bue, Brian D.; Green, Robert O.; Gerilowski, Konstantin; Krings, Thomas; Borchardt, Jakob; Kort, Eric A.; Sweeney, Colm; Conley, Stephen; Roberts, Dar A.; Dennison, Philip E.

2017-10-01

At local scales, emissions of methane and carbon dioxide are highly uncertain. Localized sources of both trace gases can create strong local gradients in its columnar abundance, which can be discerned using absorption spectroscopy at high spatial resolution. In a previous study, more than 250 methane plumes were observed in the San Juan Basin near Four Corners during April 2015 using the next-generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) and a linearized matched filter. For the first time, we apply the iterative maximum a posteriori differential optical absorption spectroscopy (IMAP-DOAS) method to AVIRIS-NG data and generate gas concentration maps for methane, carbon dioxide, and water vapor plumes. This demonstrates a comprehensive greenhouse gas monitoring capability that targets methane and carbon dioxide, the two dominant anthropogenic climate-forcing agents. Water vapor results indicate the ability of these retrievals to distinguish between methane and water vapor despite spectral interference in the shortwave infrared. We focus on selected cases from anthropogenic and natural sources, including emissions from mine ventilation shafts, a gas processing plant, tank, pipeline leak, and natural seep. In addition, carbon dioxide emissions were mapped from the flue-gas stacks of two coal-fired power plants and a water vapor plume was observed from the combined sources of cooling towers and cooling ponds. Observed plumes were consistent with known and suspected emission sources verified by the true color AVIRIS-NG scenes and higher-resolution Google Earth imagery. Real-time detection and geolocation of methane plumes by AVIRIS-NG provided unambiguous identification of individual emission source locations and communication to a ground team for rapid follow-up. This permitted verification of a number of methane emission sources using a thermal camera, including a tank and buried natural gas pipeline.

Stratospheric NO2 vertical profile retrieved from ground-based Zenith-Sky DOAS observations at Kiruna, Sweden

NASA Astrophysics Data System (ADS)

Gu, Myojeong; Enell, Carl-Fredrik; Hendrick, François; Pukite, Janis; Van Roozendael, Michel; Platt, Ulrich; Raffalski, Uwe; Wagner, Thomas

2014-05-01

Stratospheric NO2 destroys ozone and acts as a buffer against halogen-catalyzed ozone loss through the formation of reservoir species (ClONO2, BrONO2). Since the importance of both mechanisms depends on the altitude, the investigation of stratospheric NO2 vertical distribution can provide more insight into the role of nitrogen compounds in the destruction of ozone. Here we present stratospheric NO2 vertical profiles retrieved from twilight ground-based zenith-sky DOAS observations at Kiruna, Sweden (68.84°N, 20.41°E) covering 1997 - 2013 periods. This instrument observes zenith scattered sunlight. The sensitivity for stratospheric trace gases is highest during twilight due to the maximum altitude of the scattering profile and the light path through the stratosphere, which vary with the solar zenith angle. The profiling algorithm, based on the Optimal Estimation Method, has been developed by IASB-BIRA and successfully applied at other stations (Hendrick et al., 2004). The basic principle behind this profiling approach is that during twilight, the mean Rayleigh scattering altitude scans the stratosphere rapidly, providing height-resolved information on the absorption by stratospheric NO2. In this study, the long-term evolution of the stratospheric NO2 profile at polar latitude will be investigated. Hendrick, F., B. Barret, M. Van Roozendael, H. Boesch, A. Butz, M. De Mazière, F. Goutail, C. Hermans, J.-C. Lambert, K. Pfeilsticker, and J.-P. Pommereau, Retrieval of nitrogen dioxide stratospheric profiles from ground-based zenith-sky UV-visible observations: Validation of the technique through correlative comparisons, Atmospheric Chemistry and Physics, 4, 2091-2106, 2004

Simulation Study of the Localization of a Near-Surface Crack Using an Air-Coupled Ultrasonic Sensor Array

PubMed Central

Delrue, Steven; Aleshin, Vladislav; Sørensen, Mikael; De Lathauwer, Lieven

2017-01-01

The importance of Non-Destructive Testing (NDT) to check the integrity of materials in different fields of industry has increased significantly in recent years. Actually, industry demands NDT methods that allow fast (preferably non-contact) detection and localization of early-stage defects with easy-to-interpret results, so that even a non-expert field worker can carry out the testing. The main challenge is to combine as many of these requirements into one single technique. The concept of acoustic cameras, developed for low frequency NDT, meets most of the above-mentioned requirements. These cameras make use of an array of microphones to visualize noise sources by estimating the Direction Of Arrival (DOA) of the impinging sound waves. Until now, however, because of limitations in the frequency range and the lack of integrated nonlinear post-processing, acoustic camera systems have never been used for the localization of incipient damage. The goal of the current paper is to numerically investigate the capabilities of locating incipient damage by measuring the nonlinear airborne emission of the defect using a non-contact ultrasonic sensor array. We will consider a simple case of a sample with a single near-surface crack and prove that after efficient excitation of the defect sample, the nonlinear defect responses can be detected by a uniform linear sensor array. These responses are then used to determine the location of the defect by means of three different DOA algorithms. The results obtained in this study can be considered as a first step towards the development of a nonlinear ultrasonic camera system, comprising the ultrasonic sensor array as the hardware and nonlinear post-processing and source localization software. PMID:28441738

Operational trace gas column observations from GOME-2 on MetOp

NASA Astrophysics Data System (ADS)

Valks, Pieter; Hao, Nan; Pinardi, Gaia; Hedelt, Pascal; Liu, Song; Van Roozendael, Michel; De Smedt, Isabelle; Theys, Nicolas; Koukouli, MariLiza; Balis, Dimitris

2017-04-01

This contribution focuses on the operational GOME-2 trace gas column products developed in the framework of EUMETSAT's Satellite Application Facility on Atmospheric Composition Monitoring (AC-SAF). We present an overview of the retrieval algorithms for ozone, OClO, NO2, SO2 and formaldehyde, and we show examples of various applications such as air quality and climate monitoring, using observations from the GOME-2 instruments on MetOp-A and MetOp-B. Total ozone and the minor trace gas columns from GOME-2 are retrieved with the latest version 4.8 of the GOME Data Processor (GDP), which uses an optimized Differential Optical Absorption Spectroscopy (DOAS) algorithm, with air mass factor conversions based on the LIDORT model. Improved total and tropospheric NO2 columns are retrieved in the visible wavelength region between 425 and 497 nm. SO2 emissions from volcanic and anthropogenic sources can be measured by GOME-2 using the UV wavelength region around 320 nm. For formaldehyde, an optimal DOAS fitting window around 335 nm has been determined for GOME-2. The GOME-2 trace gas columns have reached the operational EUMETSAT product status, and are available to the users in near real time (within two hours after sensing by GOME-2). The use of trace gas observations from the GOME-2 instruments on MetOp-A and MetOp-B for air quality purposed will be illustrated, e.g. for South-East Asia and Europe. Furthermore, comparisons of the GOME-2 satellite observations with ground-based measurements will be shown. Finally, the use of GOME-2 trace-gas column data in the Copernicus Atmosphere Monitoring Service (CAMS) will be presented.

Tropospheric NO2 and HCHO columns derived from ground-based MAX-DOAS system in Guangzhou, China and comparison with satellite observations: First results within the EU FP7 project MarcoPolo

NASA Astrophysics Data System (ADS)

Drosoglou, Theano; Kouremeti, Natalia; Bais, Alkis; Zyrichidou, Irene; Li, Shu; Balis, Dimitris; Huang, Zhonghui

2016-04-01

A miniature MAX-DOAS system, Phaethon, has been developed at the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece, for ground-based monitoring of column densities of atmospheric gases. Simultaneous measurements with two Phaethon systems at the city centre of Thessaloniki and at a rural location about 30 km away have shown that Phaethon provides NO2 and HCHO tropospheric column measurements of acceptable accuracy under both low and high air-pollution levels. Currently three systems have been deployed in areas with different pollution patterns to support air quality and satellite validation studies. In the framework of the EU FP7 Monitoring and Assessment of Regional air quality in China using space Observations, Project Of Long-term sino-european co-Operation, MarcoPolo project, one of the Phaethon systems has been installed since April 2015 in the Guangzhou region in China. Tropospheric NO2 and HCHO columns derived at Guangzhou during the first 10 months of operation are compared with corresponding retrievals from OMI/Aura and GOME-2/Metop-A and /Metop-B satellite sensors. The area is characterized by humid subtropical monsoon climate and cloud-free conditions are rather rare from early March to mid-October. Despite this limitation and the short period of operation of Phaethon in Guangzhou, the agreement between ground-based and satellite observations is generally good for both NO2 and HCHO. It appears that GOME-2 sensors seem to underestimate the tropospheric NO2, possibly due to their large pixel size, whereas the comparison with OMI data is better, especially when a small cloud fraction (< 0.2) is used for cloud screening.

Halogen/sulphur variations over the active lava lake of Nyiragongo

NASA Astrophysics Data System (ADS)

Giuffrida, G.; Bobrowski, N.; Tedesco, D.; Yalire, M.; Arellano, S.; Balagizi, C.; Galle, B.

2010-12-01

In June 2007 and July 2010 spectroscopic measurements and chemical in-situ studies were carried out at the crater rim of the Niyragongo volcano located 15 km north of the city Goma, North Kivu region (DRC). Niyragongo volcano belongs to the Virunga volcanic chain and it is associated with the Western branch of the Great Rift Valley. The volcanism at Niyragongo is caused by the rifting of the Earth’s crust where two parts of the African plates are breaking apart. Niyragongo crater contains the biggest lava lake today and it is considered one of the most active volcanoes in Africa. The ground - based remote sensing technique - MAX-DOAS (Multi Axis Differential Optical Absorption Spectroscopy) using scattered sunlight has been applied during both field trips on top at the crater rim of the volcano to measure sulphur dioxide, halogen oxides and nitrogen oxide. Additionally filter pack and spectroscopic in-situ carbon dioxide measurements were carried out, as well as SO2 flux measurements by a scanning DOAS from the NOVAC network at the flank of the volcano. The measurements provide information on the chemical composition as well as its variability within the volcanic plume from the lava lake. The variations of the gas ratios especially BrO/SO2, between 0.3 x 10-5 and 3 x 10-5, together with the variations of SO2 emission fluxes between about 500 up to 2000 t/d, will be discussed in the light of long-term variations between 2007 and 2010, and short-term variations - small scale activity changes (e.g. lava lake overflows), which could be observed during June 2007 and July 2010. Their possible potential to improve the understanding of the volcanic system will be investigated.

Modeling the Lowest 1 Km of the Atmosphere,

DTIC Science & Technology

1981-11-01

DU TRAITE DE L’ATLANTIQUE NORD) AGARDograph No.267 MODELING THE LOWEST 1 KM OF THE ATMOSPHERE by W.S.Lewelien Aeronautical Research Associates of... elS Energy: + Uj + (k "x1)ax3 a axj k Xj Species: ka C + + Qc (2.1.9) - Uj *xj ~ axj aj aj 4 The dependent variables in Eqs. (2.1.6 - 2.1.9) have been...0.75 uiu (3.4.10) azdz K 0~ az 8z / do-a 0.3 a 1- 2\\ 0.5 __"(34.10 - - 2uju -- 0.3 + - ~~az 6 + - Aula - - 0.45 (3.4.11) The only difficulty lies with

Effet des Plastifiants sur la Temperature de Transition Vitreuse, Tg, du Butadiene a Terminaison Hydroxy et du Polyazoture de Glycidyle - Simulations et Experiences (Effect of the Plasticizers on the Vitreous Transition Temperature, Tg, of the Butadiene to Termination Hydroxy and the Polyazoture of Glycidyle - Simulations and Experiences)

DTIC Science & Technology

2008-09-01

diverses temperatures 26 a) HTPB pur b) HTPB-DOA (polymere et plastifiant) c) GAP pur d) Gpl pur e)Gap-Gpl Liste des tableaux Tableau 1...Composition des mailles amorphes construites 11 Tableau 2. Proprietes des polymeres et plastifiants utilises 11 Tableau 3. Comparaisons entre les Tt...obtenues experimentalement, les T% publiees dans les ecrits scientifiques et celles predites a partir des 7"gdes composes purs 19 Tableau 4. Comparaison

Collaborative Monitoring and Hazard Mitigation at Fuego Volcano, Guatemala

NASA Astrophysics Data System (ADS)

Lyons, J. J.; Bluth, G. J.; Rose, W. I.; Patrick, M.; Johnson, J. B.; Stix, J.

2007-05-01

A portable, digital sensor network has been installed to closely monitor changing activity at Fuego volcano, which takes advantage of an international collaborative effort among Guatemala, U.S. and Canadian universities, and the Peace Corps. The goal of this effort is to improve the understanding shallow internal processes, and consequently to more effectively mitigate volcanic hazards. Fuego volcano has had more than 60 historical eruptions and nearly-continuous activity make it an ideal laboratory to study volcanic processes. Close monitoring is needed to identify base-line activity, and rapidly identify and disseminate changes in the activity which might threaten nearby communities. The sensor network is comprised of a miniature DOAS ultraviolet spectrometer fitted with a system for automated plume scans, a digital video camera, and two seismo-acoustic stations and portable dataloggers. These sensors are on loan from scientists who visited Fuego during short field seasons and donated use of their sensors to a resident Peace Corps Masters International student from Michigan Technological University for extended data collection. The sensor network is based around the local volcano observatory maintained by Instituto National de Sismologia, Vulcanologia, Metrologia e Hidrologia (INSIVUMEH). INSIVUMEH provides local support and historical knowledge of Fuego activity as well as a secure location for storage of scientific equipment, data processing, and charging of the batteries that power the sensors. The complete sensor network came online in mid-February 2007 and here we present preliminary results from concurrent gas, seismic, and acoustic monitoring of activity from Fuego volcano.

Marine fluorescence from high spectrally resolved satellite measurements

NASA Astrophysics Data System (ADS)

Wolanin, Aleksandra; Dinter, Tilman; Rozanov, Vladimir; Noël, Stefan; Vountas, Marco; Burrows, John P.; Bracher, Astrid

2014-05-01

When chlorophyll molecules absorb light, most of this energy is transformed into chemical energy in a process of photosynthesis. However, a fraction of the energy absorbed is reemitted as fluorescence. As a result of its relationship to photosynthetic e?ciency, information about chlorophyll fluorescence can be used to assess the physiological state of phytoplankton (Falkowski and Kolber,1995). In-situ measurements of chlorophyll fluorescence are widespread in physiological and ecophysiological studies. When retrieved from space, chlorophyll fluorescence can improve our knowledge of global biogeochemical cycles and phytoplankton productivity (Behrenfeld et al., 2009; Huot et al., 2013) by providing high coverage and periodicity. So far, the only satellite retrieval of sun-induced marine fluorescence, Fluorescence Line Height (FLH), was designed for MODIS (Abbott and Letelier, 1999), and later also applied to the similar sensor MERIS (Gower et al., 2004). However, it could so far not be evaluated on global scale. Here, we present a different approach to observe marine chlorophyll fluorescence, based on the Differential Optical Absorption Spectroscopy (DOAS) technique (Perner and Platt, 1979) applied to the hyperspectral data from Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and Global Ozone Monitoring Experiment-2 (GOME-2). Since fluorescence, as a trans-spectral process, leads to the shift of the wavelength of the radiation, it can be observed in the filling-in of Fraunhofer lines. In our retrieval, we evaluate the filling-in of the Zeeman triplet Fraunhofer line FeI at 684.3 nm, which is located very close to the emission peak of marine fluorescence (~685 nm). In order to conduct the chlorophyll fluorescence retrieval with the DOAS method, we calculated the reference spectra for chlorophyll fluorescence, based on simulations performed with the coupled ocean-atmosphere radiative transfer model SCIATRAN (Rozanov et al., 2014). Based on the simulated data, we also calculated corrections the influence of for water vapor, Raman scattering and solar zenith angle on the retrieved fluorescence emissions. Our fluorescence results from SCIAMACHY and GOME-2 show similar spatial patterns when compared to the MODIS FLH. The fluorescence is generally stronger in areas of high chlorophyll concentration. The observed differences between SCIAMACHY and GOME-2 DOAS FLH and MODIS FLH arise from differences among instruments, retrieval methods, spatial and temporal sampling and overpass time. Our hyperspectral retrieval shows noisier results than MODIS FLH, but is not susceptible to certain problems as the multispectral FLH, which arise from backscattered light by particulate matter or phycocyanin fluorescence (Abbott and Letelier, 1999). For our fluorescence retrieval, we acquired better quality for the SCIAMACHY data than for GOME-2, due to the higher spectral resolution and the smaller size of the footprint. Our results demonstrate that it is feasible to detect the weak fluorescence signal from the oceans within hyperspectral data from satellite measurements. The method presented is generic and can be applied to other instruments in the future.

Instrument intercomparison of glyoxal, methyl glyoxal and NO2 under simulated atmospheric conditions

NASA Astrophysics Data System (ADS)

Thalman, R.; Baeza-Romero, M. T.; Ball, S. M.; Borrás, E.; Daniels, M. J. S.; Goodall, I. C. A.; Henry, S. B.; Karl, T.; Keutsch, F. N.; Kim, S.; Mak, J.; Monks, P. S.; Muñoz, A.; Orlando, J.; Peppe, S.; Rickard, A. R.; Ródenas, M.; Sánchez, P.; Seco, R.; Su, L.; Tyndall, G.; Vázquez, M.; Vera, T.; Waxman, E.; Volkamer, R.

2015-04-01

The α-dicarbonyl compounds glyoxal (CHOCHO) and methyl glyoxal (CH3C(O)CHO) are produced in the atmosphere by the oxidation of hydrocarbons and emitted directly from pyrogenic sources. Measurements of ambient concentrations inform about the rate of hydrocarbon oxidation, oxidative capacity, and secondary organic aerosol (SOA) formation. We present results from a comprehensive instrument comparison effort at two simulation chamber facilities in the US and Europe that included nine instruments, and seven different measurement techniques: broadband cavity enhanced absorption spectroscopy (BBCEAS), cavity-enhanced differential optical absorption spectroscopy (CE-DOAS), white-cell DOAS, Fourier transform infrared spectroscopy (FTIR, two separate instruments), laser-induced phosphorescence (LIP), solid-phase micro extraction (SPME), and proton transfer reaction mass spectrometry (PTR-ToF-MS, two separate instruments; for methyl glyoxal only because no significant response was observed for glyoxal). Experiments at the National Center for Atmospheric Research (NCAR) compare three independent sources of calibration as a function of temperature (293-330 K). Calibrations from absorption cross-section spectra at UV-visible and IR wavelengths are found to agree within 2% for glyoxal, and 4% for methyl glyoxal at all temperatures; further calibrations based on ion-molecule rate constant calculations agreed within 5% for methyl glyoxal at all temperatures. At the European Photoreactor (EUPHORE) all measurements are calibrated from the same UV-visible spectra (either directly or indirectly), thus minimizing potential systematic bias. We find excellent linearity under idealized conditions (pure glyoxal or methyl glyoxal, R2 > 0.96), and in complex gas mixtures characteristic of dry photochemical smog systems (o-xylene/NOx and isoprene/NOx, R2 > 0.95; R2 ∼ 0.65 for offline SPME measurements of methyl glyoxal). The correlations are more variable in humid ambient air mixtures (RH > 45%) for methyl glyoxal (0.58 < R2 < 0.68) than for glyoxal (0.79 < R2 < 0.99). The intercepts of correlations were insignificant for the most part (below the instruments' experimentally determined detection limits); slopes further varied by less than 5% for instruments that could also simultaneously measure NO2. For glyoxal and methyl glyoxal the slopes varied by less than 12 and 17% (both 3-σ) between direct absorption techniques (i.e., calibration from knowledge of the absorption cross section). We find a larger variability among in situ techniques that employ external calibration sources (75-90%, 3-σ), and/or techniques that employ offline analysis. Our intercomparison reveals existing differences in reports about precision and detection limits in the literature, and enables comparison on a common basis by observing a common air mass. Finally, we evaluate the influence of interfering species (e.g., NO2, O3 and H2O) of relevance in field and laboratory applications. Techniques now exist to conduct fast and accurate measurements of glyoxal at ambient concentrations, and methyl glyoxal under simulated conditions. However, techniques to measure methyl glyoxal at ambient concentrations remain a challenge, and would be desirable.

Instrument inter-comparison of glyoxal, methyl glyoxal and NO2 under simulated atmospheric conditions

NASA Astrophysics Data System (ADS)

Thalman, R.; Baeza-Romero, M. T.; Ball, S. M.; Borrás, E.; Daniels, M. J. S.; Goodall, I. C. A.; Henry, S. B.; Karl, T.; Keutsch, F. N.; Kim, S.; Mak, J.; Monks, P. S.; Muñoz, A.; Orlando, J.; Peppe, S.; Rickard, A. R.; Ródenas, M.; Sánchez, P.; Seco, R.; Su, L.; Tyndall, G.; Vázquez, M.; Vera, T.; Waxman, E.; Volkamer, R.

2014-08-01

The α-dicarbonyl compounds glyoxal (CHOCHO) and methyl glyoxal (CH3C(O)CHO) are produced in the atmosphere by the oxidation of hydrocarbons, and emitted directly from pyrogenic sources. Measurements of ambient concentrations inform about the rate of hydrocarbon oxidation, oxidative capacity, and secondary organic aerosol (SOA) formation. We present results from a comprehensive instrument comparison effort at 2 simulation chamber facilities in the US and Europe that included 9 instruments, and 7 different measurement techniques: Broadband Cavity Enhanced Absorption Spectroscopy (BBCEAS), Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS), White-cell DOAS, Fourier Transform Infra-Red Spectroscopy (FTIR, two separate instruments), Laser Induced Phosphoresence (LIP), Solid Phase Micro Extraction (SPME), and Proton Transfer Reaction Mass Spectrometry (PTR-ToF-MS, two separate instruments; only methyl glyoxal as no significant response was observed for glyoxal). Experiments at the National Center for Atmospheric Research (NCAR) compare 3 independent sources of calibration as a function of temperature (293 K to 330 K). Calibrations from absorption cross-section spectra at UV-visible and IR wavelengths are found to agree within 2% for glyoxal, and 4% for methyl glyoxal at all temperatures; further calibrations based on ion-molecule rate constant calculations agreed within 5% for methyl glyoxal at all temperatures. At the EUropean PHOtoREactor (EUPHORE) all measurements are calibrated from the same UV-visible spectra (either directly or indirectly), thus minimizing potential systematic bias. We find excellent linearity under idealized conditions (pure glyoxal or methyl glyoxal, R2 > 0.96), and in complex gas mixtures characteristic of dry photochemical smog systems (o-xylene/NOx and isoprene/NOx, R2 > 0.95; R2 ~ 0.65 for offline SPME measurements of methyl glyoxal). The correlations are more variable in humid ambient air mixtures (RH > 45%) for methyl glyoxal (0.58 < R2 < 0.68) than for glyoxal (0.79 < R2 < 0.99). The intercepts of correlations were insignificant for the most part; slopes varied by less than 5% for instruments that also measure NO2. For glyoxal and methyl glyoxal the slopes varied by less than 12% and 17% (both 3-sigma) between inherently calibrated instruments (i.e., calibration from knowledge of the absorption cross-section). We find a larger variability among in situ techniques that employ external calibration sources (75% to 90%, 3-sigma), and/or techniques that employ offline analysis. Our inter-comparison reveal existing differences in reports about precision and detection limits in the literature, and enables comparison on a common basis by observing a common airmass. Finally, we evaluate the influence of interfering species (e.g., NO2, O3 and H2O) of relevance in field and laboratory applications. Techniques now exist to conduct fast and accurate measurements of glyoxal at ambient concentrations, and methyl glyoxal under simulated conditions. However, techniques to measure methyl glyoxal at ambient concentrations remain a challenge, and would be desirable.

Aircraft measurements of BrO, IO, glyoxal, NO 2, H 2O, O 2–O 2 and aerosol extinction profiles in the tropics: comparison with aircraft-/ship-based in situ and lidar measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Volkamer, Rainer; Baidar, S.; Campos, T. L.

Here, tropospheric chemistry of halogens and organic carbon over tropical oceans modifies ozone and atmospheric aerosols, yet atmospheric models remain largely untested for lack of vertically resolved measurements of bromine monoxide (BrO), iodine monoxide (IO) and small oxygenated hydrocarbons like glyoxal (CHOCHO) in the tropical troposphere. BrO, IO, glyoxal, nitrogen dioxide (NO 2), water vapor (H 2O) and O 2–O 2 collision complexes (O 4) were measured by the University of Colorado Airborne Multi-AXis Differential Optical Absorption Spectroscopy (CU AMAX-DOAS) instrument, aerosol extinction by high spectral resolution lidar (HSRL), in situ aerosol size distributions by an ultra high sensitivity aerosolmore » spectrometer (UHSAS) and in situ H 2O by vertical-cavity surface-emitting laser (VCSEL) hygrometer. Data are presented from two research flights (RF12, RF17) aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V aircraft over the tropical Eastern Pacific Ocean (tEPO) as part of the "Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated hydrocarbons" (TORERO) project (January/February 2012). We assess the accuracy of O 4 slant column density (SCD) measurements in the presence and absence of aerosols. Our O 4-inferred aerosol extinction profiles at 477 nm agree within 6% with HSRL in the boundary layer and closely resemble the renormalized profile shape of Mie calculations constrained by UHSAS at low (sub-Rayleigh) aerosol extinction in the free troposphere. CU AMAX-DOAS provides a flexible choice of geometry, which we exploit to minimize the SCD in the reference spectrum (SCD REF, maximize signal-to-noise ratio) and to test the robustness of BrO, IO and glyoxal differential SCDs. The RF12 case study was conducted in pristine marine and free tropospheric air. The RF17 case study was conducted above the NOAA RV Ka'imimoana (TORERO cruise, KA-12-01) and provides independent validation data from ship-based in situ cavity-enhanced DOAS and MAX-DOAS. Inside the marine boundary layer (MBL) no BrO was detected (smaller than 0.5 pptv), and 0.2–0.55 pptv IO and 32–36 pptv glyoxal were observed. The near-surface concentrations agree within 30% (IO) and 10% (glyoxal) between ship and aircraft. The BrO concentration strongly increased with altitude to 3.0 pptv at 14.5 km (RF12, 9.1 to 8.6° N; 101.2 to 97.4° W). At 14.5 km, 5–10 pptv NO 2 agree with model predictions and demonstrate good control over separating tropospheric from stratospheric absorbers (NO 2 and BrO). Our profile retrievals have 12–20 degrees of freedom (DoF) and up to 500 m vertical resolution. The tropospheric BrO vertical column density (VCD) was 1.5 × 10 13 molec cm –2 (RF12) and at least 0.5 × 10 13 molec cm –2 (RF17, 0–10 km, lower limit). Tropospheric IO VCDs correspond to 2.1 × 10 12 molec cm –2 (RF12) and 2.5 × 10 12 molec cm –2 (RF17) and glyoxal VCDs of 2.6 × 10 14 molec cm –2 (RF12) and 2.7 × 10 14 molec cm –2 (RF17). Surprisingly, essentially all BrO as well as the dominant IO and glyoxal VCD fraction was located above 2 km (IO: 58 ± 5%, 0.1–0.2 pptv; glyoxal: 52 ± 5%, 3–20 pptv). To our knowledge there are no previous vertically resolved measurements of BrO and glyoxal from aircraft in the tropical free troposphere. The atmospheric implications are briefly discussed. Future studies are necessary to better understand the sources and impacts of free tropospheric halogens and oxygenated hydrocarbons on tropospheric ozone, aerosols, mercury oxidation and the oxidation capacity of the atmosphere.« less

Study of cross-shaped ultrasonic array sensor applied to partial discharge location in transformer oil.

PubMed

Li, Jisheng; Xin, Xiaohu; Luo, Yongfen; Ji, Haiying; Li, Yanming; Deng, Junbo

2013-11-01

A conformal combined sensor is designed and it is used in Partial Discharge (PD) location experiments in transformer oil. The sensor includes a cross-shaped ultrasonic phased array of 13 elements and an ultra-high-frequency (UHF) electromagnetic rectangle array of 2 × 2 elements. Virtual expansion with high order cumulants, the ultrasonic array can achieve the effect of array with 61 elements. This greatly improves the aperture and direction sharpness of original array and reduces the cost of follow-up hardware. With the cross-shaped ultrasonic array, the results of PD location experiments are precise and the maximum error of the direction of arrival (DOA) is less than 5°.

Small Whiskbroom Imager for atmospheric compositioN monitorinG (SWING) from an Unmanned Aerial Vehicle (UAV): Results from the 2014 AROMAT campaign

NASA Astrophysics Data System (ADS)

Merlaud, Alexis; Tack, Frederik; Constantin, Daniel; Fayt, Caroline; Maes, Jeroen; Mingireanu, Florin; Mocanu, Ionut; Georgescu, Lucian; Van Roozendael, Michel

2015-04-01

The Small Whiskbroom Imager for atmospheric compositioN monitorinG (SWING) is an instrument dedicated to atmospheric trace gas retrieval from an Unmanned Aerial Vehicle (UAV). The payload is based on a compact visible spectrometer and a scanning mirror to collect scattered sunlight. Its weight, size, and power consumption are respectively 920 g, 27x12x12 cm3, and 6 W. The custom-built 2.5 m flying wing UAV is electrically powered, has a typical airspeed of 100 km/h, and can operate at a maximum altitude of 3 km. Both the payload and the UAV were developed in the framework of a collaboration between the Belgian Institute for Space Aeronomy (BIRA-IASB) and the Dunarea de Jos University of Galati, Romania. We present here SWING-UAV test flights dedicated to NO2 measurements and performed in Romania on 10 and 11 September 2014, during the Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaign. The UAV performed 5 flights in the vicinity of the large thermal power station of Turceni (44.67° N, 23.4° E). The UAV was operated in visual range during the campaign, up to 900 m AGL , downwind of the plant and crossing its exhaust plume. The spectra recorded on flight are analyzed with the Differential Optical Absorption Spectroscopy (DOAS) method. The retrieved NO2 Differential Slant Column Densities (DSCDs) are up to 1.5e17 molec/cm2 and reveal the horizontal gradients around the plant. The DSCDs are converted to vertical columns and compared with coincident car-based DOAS measurements. We also present the near-future perspective of the SWING-UAV observation system, which includes flights in 2015 above the Black Sea to quantify ship emissions, the addition of SO2 as a target species, and autopilot flights at higher altitudes to cover a typical satellite pixel extent (10x10 km2).

A Comparison of Multiscale Permutation Entropy Measures in On-Line Depth of Anesthesia Monitoring

PubMed Central

Li, Xiaoli; Li, Duan; Li, Yongwang; Ursino, Mauro

2016-01-01

Objective Multiscale permutation entropy (MSPE) is becoming an interesting tool to explore neurophysiological mechanisms in recent years. In this study, six MSPE measures were proposed for on-line depth of anesthesia (DoA) monitoring to quantify the anesthetic effect on the real-time EEG recordings. The performance of these measures in describing the transient characters of simulated neural populations and clinical anesthesia EEG were evaluated and compared. Methods Six MSPE algorithms—derived from Shannon permutation entropy (SPE), Renyi permutation entropy (RPE) and Tsallis permutation entropy (TPE) combined with the decomposition procedures of coarse-graining (CG) method and moving average (MA) analysis—were studied. A thalamo-cortical neural mass model (TCNMM) was used to generate noise-free EEG under anesthesia to quantitatively assess the robustness of each MSPE measure against noise. Then, the clinical anesthesia EEG recordings from 20 patients were analyzed with these measures. To validate their effectiveness, the ability of six measures were compared in terms of tracking the dynamical changes in EEG data and the performance in state discrimination. The Pearson correlation coefficient (R) was used to assess the relationship among MSPE measures. Results CG-based MSPEs failed in on-line DoA monitoring at multiscale analysis. In on-line EEG analysis, the MA-based MSPE measures at 5 decomposed scales could track the transient changes of EEG recordings and statistically distinguish the awake state, unconsciousness and recovery of consciousness (RoC) state significantly. Compared to single-scale SPE and RPE, MSPEs had better anti-noise ability and MA-RPE at scale 5 performed best in this aspect. MA-TPE outperformed other measures with faster tracking speed of the loss of unconsciousness. Conclusions MA-based multiscale permutation entropies have the potential for on-line anesthesia EEG analysis with its simple computation and sensitivity to drug effect changes. CG-based multiscale permutation entropies may fail to describe the characteristics of EEG at high decomposition scales. PMID:27723803

piscope - A Python based software package for the analysis of volcanic SO2 emissions using UV SO2 cameras

NASA Astrophysics Data System (ADS)

Gliss, Jonas; Stebel, Kerstin; Kylling, Arve; Solvejg Dinger, Anna; Sihler, Holger; Sudbø, Aasmund

2017-04-01

UV SO2 cameras have become a common method for monitoring SO2 emission rates from volcanoes. Scattered solar UV radiation is measured in two wavelength windows, typically around 310 nm and 330 nm (distinct / weak SO2 absorption) using interference filters. The data analysis comprises the retrieval of plume background intensities (to calculate plume optical densities), the camera calibration (to convert optical densities into SO2 column densities) and the retrieval of gas velocities within the plume as well as the retrieval of plume distances. SO2 emission rates are then typically retrieved along a projected plume cross section, for instance a straight line perpendicular to the plume propagation direction. Today, for most of the required analysis steps, several alternatives exist due to ongoing developments and improvements related to the measurement technique. We present piscope, a cross platform, open source software toolbox for the analysis of UV SO2 camera data. The code is written in the Python programming language and emerged from the idea of a common analysis platform incorporating a selection of the most prevalent methods found in literature. piscope includes several routines for plume background retrievals, routines for cell and DOAS based camera calibration including two individual methods to identify the DOAS field of view (shape and position) within the camera images. Gas velocities can be retrieved either based on an optical flow analysis or using signal cross correlation. A correction for signal dilution (due to atmospheric scattering) can be performed based on topographic features in the images. The latter requires distance retrievals to the topographic features used for the correction. These distances can be retrieved automatically on a pixel base using intersections of individual pixel viewing directions with the local topography. The main features of piscope are presented based on dataset recorded at Mt. Etna, Italy in September 2015.

Airborne remote-sensing of atmospheric CH4 and CO2 with MAMap: first results of measurements over wetlands in Germany and a N-S transect from Canada to Chile

NASA Astrophysics Data System (ADS)

Tretner, A.; Gerilowski, K.; Bovensmann, H.; Buchwitz, M.; Bertagnolio, P. P.; Erzinger, J.; Burrows, J.

2008-12-01

The Methane Airborne Mapper (MAMap) was designed for CO2 and CH4 remote sensing of the atmospheric column between an aircraft and the Earth's surface. The instrument is specified to detect mixing ratio variations below the aircraft of <3% of the atmospheric background as well as a ground pixel size of 20m x 20m (700m flight height, 200 km/h flight speed). It allows the detection of CO2 and CH4 gradients on a local, regional and global scale, and provides a link between ground-based and satellite- based measurements. The goal of the MAMap measurements is to improve the knowledge of CH4 and CO2 sources and sinks. In 2007 and 2008, several flight campaigns over bogs and wetlands have been conducted in Germany and correlated to ground-based measurements. A first version of the data retrieval has been developed using a modified version of the WFM-DOAS algorithm. WFM-DOAS is also used for the retrieval of CH4 and CO2 column concentrations from nadir measurements by SCIAMACHY onboard ENVISAT. In November 2008, a transect from Oshawa, Canada to Punta Arenas, Chile will be flown onboard the AWI POLAR 5 aircraft. Along the flight path CH4 and CO2 measurements will be conducted by MAMap. Besides the N-S track (Canada-USA-Bahamas-Panama-Ecuador-Peru-Chile), an additional W-E track from Guayaquil (Ecuador) to Iquitos (Peru) and back is planned, covering large areas of Peruvian rainforest. One focus of this project is the evaluation of tropical rain forest and savannah as sources/sinks of CH4 and CO2. Discrepancies between the models and satellite data regarding atmospheric CH4 concentrations over the tropics have been reported in the past. A first assessment of MAMap measurements performed in 2008 over wetlands in Germany and the AWI-POLAR 5 campaign will be presented.

Mapping-by-sequencing of Ligon-lintless-1 (Li 1 ) reveals a cluster of neighboring genes with correlated expression in developing fibers of Upland cotton (Gossypium hirsutum L.).

PubMed

Thyssen, Gregory N; Fang, David D; Turley, Rickie B; Florane, Christopher; Li, Ping; Naoumkina, Marina

2015-09-01

Mapping-by-sequencing and SNP marker analysis were used to fine map the Ligon-lintless-1 ( Li 1 ) short fiber mutation in tetraploid cotton to a 255-kb region that contains 16 annotated proteins. The Ligon-lintless-1 (Li 1 ) mutant of cotton (Gossypium hirsutum L.) has been studied as a model for cotton fiber development since its identification in 1929; however, the causative mutation has not been identified yet. Here we report the fine genetic mapping of the mutation to a 255-kb region that contains only 16 annotated genes in the reference Gossypium raimondii genome. We took advantage of the incompletely dominant dwarf vegetative phenotype to identify 100 mutants (Li 1 /Li 1 ) and 100 wild-type (li 1 /li 1 ) homozygotes from a mapping population of 2567 F2 plants, which we bulked and deep sequenced. Since only homozygotes were sequenced, we were able to use a high stringency in SNP calling to rapidly narrow down the region harboring the Li 1 locus, and designed subgenome-specific SNP markers to test the population. We characterized the expression of all sixteen genes in the region by RNA sequencing of elongating fibers and by RT-qPCR at seven time points spanning fiber development. One of the most highly expressed genes found in this interval in wild-type fiber cells is 40-fold under-expressed at the day of anthesis (DOA) in the mutant fiber cells.  This gene is a major facilitator superfamily protein, part of the large family of proteins that includes auxin and sugar transporters. Interestingly, nearly all genes in this region were most highly expressed at DOA and showed a high degree of co-expression. Further characterization is required to determine if transport of hormones or carbohydrates is involved in both the dwarf and lintless phenotypes of Li 1 plants.

Validation of the Only Commercially Available Immunoassay for Synthetic Cathinones in Urine: Randox Drugs of Abuse V Biochip Array Technology

PubMed Central

Ellefsen, Kayla N.; Anizan, Sébastien; Castaneto, Marisol S.; Desrosiers, Nathalie A.; Martin, LTC Thomas M.; Klette, CAPT Kevin L.; Huestis, Marilyn A.

2014-01-01

Deterrence of synthetic cathinone abuse is hampered by the lack of a high-throughput immunoassay screen. The Randox Drugs of Abuse V biochip immunoassay (DOA-V) contains two synthetic cathinones antibodies: Bath Salt I (BSI) targets mephedrone/methcathinone and Bath Salt II (BSII) targets 3’,4’-methylenedioxypyrovalerone (MDPV)/3’,4’-methylenedioxy-α-pyrrolidinobutiophenone (MDPBP). We evaluated DOA-V synthetic cathinones performance and conducted a full validation on the original assay with calibrators reconstituted in water, and the new assay with calibrators prepared in lyophilized urine; both utilized the same antibodies and were run on the fully automated Evidence® Analyzer. 20,017 authentic military urine specimens were screened and confirmed by LC-MS/MS for 28 synthetic cathinones. Limits of detection (LOD) for the original and new assays were 0.35 and 0.18 (BSI), and 8.5 and 9.2µg/L (BSII), respectively. Linearity was acceptable (R2>0.98); however, a large negative bias was observed with in-house prepared calibrators. Intra-assay imprecision was <20% BSI-II, while inter-assay imprecision was 18–42% BSI and <22% BSII. Precision was acceptable for Randox controls. Cross-reactivities of many additional synthetic cathinones were determined. Authentic drug-free negative urine pH <4 produced false positive results for BSI (6.3µg/L) and BSII (473µg/L). Oxidizing agents reduced BSI and increased BSII results. Sensitivity, specificity, and efficiency of 100%, 52.1%, and 53.0% were obtained at manufacturer’s proposed cutoffs (BSI 5µg/L, BSII 30µg/L). Performance improved if cutoff concentrations increased (BSI 7.5µg/L, BSII 40µg/L); however, there were limited confirmed positive specimens. Currently, this is the first and only fully validated immunoassay for preliminary detection of synthetic cathinones in urine. PMID:24659527

A Comparison of Multiscale Permutation Entropy Measures in On-Line Depth of Anesthesia Monitoring.

PubMed

Su, Cui; Liang, Zhenhu; Li, Xiaoli; Li, Duan; Li, Yongwang; Ursino, Mauro

2016-01-01

Multiscale permutation entropy (MSPE) is becoming an interesting tool to explore neurophysiological mechanisms in recent years. In this study, six MSPE measures were proposed for on-line depth of anesthesia (DoA) monitoring to quantify the anesthetic effect on the real-time EEG recordings. The performance of these measures in describing the transient characters of simulated neural populations and clinical anesthesia EEG were evaluated and compared. Six MSPE algorithms-derived from Shannon permutation entropy (SPE), Renyi permutation entropy (RPE) and Tsallis permutation entropy (TPE) combined with the decomposition procedures of coarse-graining (CG) method and moving average (MA) analysis-were studied. A thalamo-cortical neural mass model (TCNMM) was used to generate noise-free EEG under anesthesia to quantitatively assess the robustness of each MSPE measure against noise. Then, the clinical anesthesia EEG recordings from 20 patients were analyzed with these measures. To validate their effectiveness, the ability of six measures were compared in terms of tracking the dynamical changes in EEG data and the performance in state discrimination. The Pearson correlation coefficient (R) was used to assess the relationship among MSPE measures. CG-based MSPEs failed in on-line DoA monitoring at multiscale analysis. In on-line EEG analysis, the MA-based MSPE measures at 5 decomposed scales could track the transient changes of EEG recordings and statistically distinguish the awake state, unconsciousness and recovery of consciousness (RoC) state significantly. Compared to single-scale SPE and RPE, MSPEs had better anti-noise ability and MA-RPE at scale 5 performed best in this aspect. MA-TPE outperformed other measures with faster tracking speed of the loss of unconsciousness. MA-based multiscale permutation entropies have the potential for on-line anesthesia EEG analysis with its simple computation and sensitivity to drug effect changes. CG-based multiscale permutation entropies may fail to describe the characteristics of EEG at high decomposition scales.

MAX-DOAS measurements of shipping emissions

NASA Astrophysics Data System (ADS)

Seyler, André; Wittrock, Folkard; Kattner, Lisa; Mathieu-Üffing, Barbara; Peters, Enno; Richter, Andreas; Schmolke, Stefan; Theobald, Norbert; Burrows, John P.

2015-04-01

Air pollution from ships contributes to overall air quality problems and it has direct health effects on the population in particular in coastal regions, and in harbor cities. In order to reduce the emissions the International Maritime Organisation (IMO) have tightened the regulations for air pollution. E.g. Sulfur Emission Control Areas (SECA) have been introduced where the sulfur content of marine fuel is limited. Recently, on the 1st of January 2015, the allowed sulfur content of marine fuels inside Sulfur Emission Control Areas has been significantly decreased from 1.0% to 0.1%. However, up to now there is no regular monitoring system available to verify that ships are complying with the new regulations. Furthermore measurements of reactive trace gases in marine environments are in general sparse. The project MeSMarT (Measurements of shipping emissions in the marine troposphere, www.mesmart.de) has been established as a cooperation between the University of Bremen and the German Bundesamt für Seeschifffahrt und Hydrographie (Federal Maritime and Hydrographic Agency) with support of the Helmholtz Research Centre Geesthacht to estimate the influence of ship emissions on the chemistry of the atmospheric boundary layer and to establish a monitoring system for main shipping routes. Here we present MAX-DOAS observations of NO2 and SO2 carried out from two permanent sites close to the Elbe river (Wedel, Germany) and on the island Neuwerk close to the mouths of Elbe and Weser river since the year 2013. Mixing ratios of both trace gases have been retrieved using different approaches (pure geometric and taking into account the radiative transfer) and compared to in situ observations (see Kattner et al., Monitoring shipping fuel sulfur content regulations with in-situ measurements of shipping emissions). Furthermore, simple approaches have been used to calculate emission factors of NOx and SO2 for single ships.

Female ejaculation orgasm vs. coital incontinence: a systematic review.

PubMed

Pastor, Zlatko

2013-07-01

Women may expel various kinds of fluids during sexual arousal and at orgasm. Their origins, quantity, compositions, and expulsion mechanisms depend on anatomical and pathophysiological dispositions and the degree of sexual arousal. These are natural sexual responses but may also represent symptoms of urinary incontinence. The study aims to clarify the etiology of fluid leakage at orgasm, distinguish between associated physiological sexual responses, and differentiate these phenomena from symptoms of illness. A systematic literature review was performed. EMBASE (OvidSP) and Web of Science databases were searched for the articles on various phenomena of fluid expulsions in women during sexual arousal and at orgasm. Articles included focused on female ejaculation and its variations, coital incontinence (CI), and vaginal lubrication. Female ejaculation orgasm manifests as either a female ejaculation (FE) of a smaller quantity of whitish secretions from the female prostate or a squirting of a larger amount of diluted and changed urine. Both phenomena may occur simultaneously. The prevalence of FE is 10-54%. CI is divided into penetration and orgasmic forms. The prevalence of CI is 0.2-66%. Penetration incontinence occurs more frequently and is usually caused by stress urinary incontinence (SUI). Urodynamic diagnoses of detrusor overactivity (DOA) and SUI are observed in orgasmic incontinence. Fluid expulsions are not typically a part of female orgasm. FE and squirting are two different physiological components of female sexuality. FE was objectively evidenced only in tens of cases but its reported high prevalence is based mostly on subjective questionnaire research. Pathophysiology of squirting is rarely documented. CI is a pathological sign caused by urethral disorder, DOA, or a combination of both, and requires treatment. An in-depth appreciation of these similar but pathophysiologically distinct phenomena is essential for distinguishing normal, physiological sexual responses from signs of illness. © 2013 International Society for Sexual Medicine.

Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements

NASA Astrophysics Data System (ADS)

Noël, Stefan; Bramstedt, Klaus; Hilker, Michael; Liebing, Patricia; Plieninger, Johannes; Reuter, Max; Rozanov, Alexei; Sioris, Christopher E.; Bovensmann, Heinrich; Burrows, John P.

2016-04-01

Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called onion peeling DOAS (ONPD), which combines an onion peeling approach with a weighting function DOAS (differential optical absorption spectroscopy) fit in the spectral region between 1559 and 1671 nm. By use of updated pointing information and optimisation of the data selection as well as of the retrieval approach, the altitude range for reasonable CH4 could be broadened from 20 to 40 km to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles (17-45 km) of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5-10 % for CH4 and 2-3 % for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002-April 2012) and the latitudinal range between about 50 and 70° N have been derived. Based on these time series, CH4 and CO2 trends have been estimated. CH4 trends above about 20 km are not significantly different from zero and the trend at 17 km is about 3 ppbv year-1. The derived CO2 trends show a general decrease with altitude with values of about 1.9 ppmv year-1 at 21 km and about 1.3 ppmv year-1 at 39 km. These results are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere.

Mobile Optical Remote Sensing Measurements of VOC's to Quantify Emissions and to Map Impact

NASA Astrophysics Data System (ADS)

Mellqvist, J.; Samuelsson, J.; Marianne, E.; Brohede, S.; Andersson, P.; Johansson, J.; Izos, O.; Polidori, A.; Pikelnaya, O.

2017-12-01

Industrial volatile organic compound (VOC) emissions may cause direct health problems and contribute significantly to ozone formation. In order to investigate how small sources contribute to the VOC concentrations in the Los Angeles metropolitan area a comprehensive emission study has been carried out on behalf of the South Coast Air Quality Management District (SCAQMD). Emission measurements of alkanes, alkenes, aromatic VOCs and methane from major sources such as refineries, oil wells, petrol stations oil depots and oil platforms were measured in an intensive campaign during the fall of 2015 using several unique optical methods, including the Solar Occultation Flux method (SOF) and tracer correlation technique based on extractive FTIR and DOAS combined with an open path multi reflection cell. In 2017 these measurements have been continued during four shorter campaigns on several of the identified hot spot emission sites. The objective has been to study the time evolution and annual variation of the emission sources and their impact on the surroundings. The latter has been carried out by mobile mapping of VOC concentrations downwind of the sources and comparison to low cost portable PID sensors. The results from the field campaigns show that the emissions from the above mentioned sources are largely underestimated in inventories with potential impact on the air quality in the Los Angeles metropolitan area. In this presentation we will describe the optical techniques and describe recent standardization work carried out in Europe and the US. In addition, results from the measurements in the LA-basin will be shown and discussed.

Remote Sensing of Stratospheric Trace Gases by TELIS

NASA Astrophysics Data System (ADS)

Xu, Jian; Schreier, Franz; Doicu, Adrian; Birk, Manfred; Wagner, Georg; Trautmann, Thomas

2015-11-01

TELIS (TErahertz and submillimeter LImb Sounder) is a balloon-borne cryogenic heterodyne spectrometer with two far infrared and submillimeter channels (1.8THz and 480-650GHz developed by DLR and SRON, respectively). The instrument was designed to investigate atmospheric chemistry and dynamics with a focus on the stratosphere. Between 2009 and 2011, TELIS participated in three winter campaigns in Kiruna, Sweden. The recent campaign took place in 2014 over Timmins, Canada. During previous campaigns, TELIS shared a stratospheric balloon gondola with the balloon version of MIPAS (MIPAS-B) and mini-DOAS. The primary scientific goal of these campaigns has been to monitor the time-dependent chemistry of chlorine and bromine, and to achieve the closure of chemical families inside the polar vortex. In this work, we present retrieved profiles of ozone (O3), hydrogen chlorine (HCl), carbon monoxide (CO), and hydroxyl radical (OH) obtained by the 1.8 THz channel from the polar winter flights during 2009-2011. Furthermore, the corresponding retrieval algorithm is briefly described. The quality of the retrieval products is analyzed in a quantitative manner including: error characterization, internal comparisons of the two different channels, and external comparisons with coincident spaceborne observations. The errors due to the instrument parameters and pressure dominate in the upper troposphere and lower stratosphere, while the errors at higher altitudes are mainly due to the spectroscopic parameters and the radiometric calibration. The comparisons with other limb sounders help us to assess the measurement capabilities and instrument characteristics of TELIS, thereby establishing the instrument as a valuable tool to study the chemical interactions in the stratosphere.

Quantitative imaging of volcanic plumes — Results, needs, and future trends

USGS Publications Warehouse

Platt, Ulrich; Lübcke, Peter; Kuhn, Jonas; Bobrowski, Nicole; Prata, Fred; Burton, Mike; Kern, Christoph

2015-01-01

Recent technology allows two-dimensional “imaging” of trace gas distributions in plumes. In contrast to older, one-dimensional remote sensing techniques, that are only capable of measuring total column densities, the new imaging methods give insight into details of transport and mixing processes as well as chemical transformation within plumes. We give an overview of gas imaging techniques already being applied at volcanoes (SO2cameras, imaging DOAS, FT-IR imaging), present techniques where first field experiments were conducted (LED-LIDAR, tomographic mapping), and describe some techniques where only theoretical studies with application to volcanology exist (e.g. Fabry–Pérot Imaging, Gas Correlation Spectroscopy, bi-static LIDAR). Finally, we discuss current needs and future trends in imaging technology.

Research on anti - interference based on GNSS

NASA Astrophysics Data System (ADS)

Yu, Huanran; Liu, Yijun

2017-05-01

Satellite Navigation System has been widely used in military and civil fields. It has all-functional, all-weather, continuity and real-time characteristics, can provide the precise position, velocity and timing information's for the users. The environments where the receiver of satellite navigation system works become more and more complex, and the satellite signals are susceptible to intentional or unintentional interferences, anti-jamming capability has become a key problem of satellite navigation receiver's ability to work normal. In this paper, we study a DOA estimation algorithm based on linear symmetric matrix to improve the anti-jamming capability of the satellite navigation receiver, has great significance to improve the performance of satellite navigation system in complex electromagnetic environment and enhance its applicability in various environments.

Multiple Signal Classification for Gravitational Wave Burst Search

NASA Astrophysics Data System (ADS)

Cao, Junwei; He, Zhengqi

2013-01-01

This work is mainly focused on the application of the multiple signal classification (MUSIC) algorithm for gravitational wave burst search. This algorithm extracts important gravitational wave characteristics from signals coming from detectors with arbitrary position, orientation and noise covariance. In this paper, the MUSIC algorithm is described in detail along with the necessary adjustments required for gravitational wave burst search. The algorithm's performance is measured using simulated signals and noise. MUSIC is compared with the Q-transform for signal triggering and with Bayesian analysis for direction of arrival (DOA) estimation, using the Ω-pipeline. Experimental results show that MUSIC has a lower resolution but is faster. MUSIC is a promising tool for real-time gravitational wave search for multi-messenger astronomy.

Aerosols correction of the OMI tropospheric NO2 retrievals over cloud-free scenes: Different methodologies based on the O2-O2 477 nm band

NASA Astrophysics Data System (ADS)

Chimot, Julien; Vlemmix, Tim; Veefkind, Pepijn; Levelt, Pieternel

2016-04-01

Numerous studies have drawn attention to the complexities related to the retrievals of tropospheric NO2 columns derived from satellite UltraViolet-Visible (UV-Vis) measurements in the presence of aerosols. Correction for aerosol effects will remain a challenge for the next generation of air quality satellite instruments such as TROPOMI on Sentinel-5 Precursor, Sentinel-4 and Sentinel-5. The Ozone Monitoring Instrument (OMI) instrument has provided daily global measurements of tropospheric NO2 for more than a decade. However, aerosols are not explicitly taken into account in the current operational OMI tropospheric NO2 retrieval chain (DOMINO v2 [Boersma et al., 2011]). Our study analyses 2 approaches for an operational aerosol correction, based on the use of the O2-O2 477 nm band. The 1st approach is the cloud-model based aerosol correction, also named "implicit aerosol correction", and already used in the operational chain. The OMI O2-O2 cloud retrieval algorithm, based on the Differential Optical Absorption Spectroscopy (DOAS) approach, is applied both to cloudy and to cloud-free scenes with aerosols present. Perturbation of the OMI cloud retrievals over scenes dominated by aerosols has been observed in recent studies led by [Castellanos et al., 2015; Lin et al., 2015; Lin et al., 2014]. We investigated the causes of these perturbations by: (1) confronting the OMI tropospheric NO2, clouds and MODIS AQUA aerosol products; (2) characterizing the key drivers of the aerosol net effects, compared to a signal from clouds, in the UV-Vis spectra. This study has focused on large industrialised areas like East-China, over cloud-free scenes. One of the key findings is the limitation due to the coarse sampling of the employed cloud Look-Up Table (LUT) to convert the results of the applied DOAS fit into effective cloud fraction and pressure. This leads to an underestimation of tropospheric NO2 amount in cases of particles located at elevated altitude. A higher sampling of the variation of O2-O2 SCD and continuum reflectance as a function of effective cloud parameters in case of low effective cloud fraction values is requested for applying an aerosol correction. The updates of the OMI O2-O2 cloud algorithm, based on the scheduled new OMI cloud LUT, will be presented in terms of impacts of the effective cloud retrievals and reduced biases of tropospheric NO2 columns over cloud-free scenes dominated by aerosols in China. A 2nd approach is investigated, assuming a more explicit aerosol correction. Previous analyses pointed out that the O2-O2 spectra contain information about aerosols: the continuum reflectance is primarily constrained by the Aerosol Optical thickness (AOT) while the O2-O2 Slant Column Density (SCD) mostly results from the combination of AOT and aerosols altitude. We have developed a first prototype algorithm allowing to retrieve information about AOT and aerosol altitude from the O2-O2 DOAS fit. We will discuss preliminary sensitivities and the potential accuracy of the associated explicit aerosol correction, without the use of effective cloud parameters.

Parameterization retrieval of trace gas volume mixing ratios from Airborne MAX-DOAS

NASA Astrophysics Data System (ADS)

Dix, Barbara; Koenig, Theodore K.; Volkamer, Rainer

2016-11-01

We present a parameterization retrieval of volume mixing ratios (VMRs) from differential slant column density (dSCD) measurements by Airborne Multi-AXis Differential Optical Absorption Spectroscopy (AMAX-DOAS). The method makes use of the fact that horizontally recorded limb spectra (elevation angle 0°) are strongly sensitive to the atmospheric layer at instrument altitude. These limb spectra are analyzed using reference spectra that largely cancel out column contributions from above and below the instrument, so that the resulting limb dSCDs, i.e., the column integrated concentration with respect to a reference spectrum, are almost exclusively sensitive to the atmospheric layers around instrument altitude. The conversion of limb dSCDs into VMRs is then realized by calculating box air mass factors (Box-AMFs) for a Rayleigh atmosphere and applying a scaling factor constrained by O4 dSCDs to account for aerosol extinction. An iterative VMR retrieval scheme corrects for trace gas profile shape effects. Benefits of this method are (1) a fast conversion that only requires the computation of Box-AMFs in a Rayleigh atmosphere; (2) neither local aerosol extinction nor the slant column density in the DOAS reference (SCDref) needs to be known; and (3) VMRs can be retrieved for every measurement point along a flight track, thus increasing statistics and adding flexibility to capture concentration gradients. Sensitivity studies are performed for bromine monoxide (BrO), iodine monoxide (IO) and nitrogen dioxide (NO2), using (1) simulated dSCD data for different trace gas and aerosol profiles and (2) field measurements from the Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxygenated VOC (TORERO) field experiment. For simulated data in a Rayleigh atmosphere, the agreement between the VMR from the parameterization method (VMRpara) and the true VMR (VMRtrue) is excellent for all trace gases. Offsets, slopes and R2 values for the linear fit of VMRpara over VMRtrue are, respectively (0.008 ± 0.001) pptv, 0.988 ± 0.001, 0.987 for BrO; (-0.0066 ± 0.0001) pptv, 1.0021 ± 0.0003, 0.9979 for IO; (-0.17 ± 0.03) pptv, 1.0036 ± 0.0001, 0.9997 for NO2. The agreement for atmospheres with aerosol shows comparable R2 values to the Rayleigh case, but slopes deviate a bit more from one: (0.093 ± 0.002) pptv, 0.933 ± 0.002, 0.907 for BrO; (0.0021 ± 0.0004) pptv, 0.887 ± 0.001, 0.973 for IO; (8.5 ± 0.1) pptv, 0.8302 ± 0.0006, 0.9923 for NO2. VMRpara from field data are further compared with optimal estimation retrievals (VMROE). Least orthogonal distance fit of the data give the following equations: BrOpara = (0.1 ± 0.2) pptv + (0.95 ± 0.14) × BrOOE; IOpara = (0.01 ± 0.02) pptv + (1.00 ± 0.12) × IOOE; NO2para = (3.9 ± 2.5) pptv + (0.87 ± 0.15) × NO2OE. Overall, we conclude that the parameterization retrieval is accurate with an uncertainty of 20 % for IO, 30 % for BrO and NO2, but not better than 0.05 pptv IO, 0.5 pptv BrO and 10 pptv NO2. The retrieval is applicable over a wide range of atmospheric conditions and measurement geometries and not limited to the interpretation of vertical profile measurements in the remote troposphere.

Infrasonic detection performance in presence of nuisance signal

NASA Astrophysics Data System (ADS)

Charbit, Maurice; Arrowsmith, Stephen; Che, Il-young; Le Pichon, Alexis; Nouvellet, Adrien; Park, Junghyun; Roueff, Francois

2014-05-01

The infrasound network of the International Monitoring System (IMS) consists of sixty stations deployed all over the World by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The IMS has been designed to reliably detect, at least by two stations, an explosion greater than 1 kiloton located anywhere on the Earth [1]. Each station is an array of at least four microbarometers with an aperture of 1 to 3 km. The first important issue is to detect the presence of the signal of interest (SOI) embedded in noise. The detector is commonly based on the property that the SOI provides coherent observations on the sensors but not the noise. The statistic of test, called F-stat [2], [5], [6] , calculated in a time cell a few seconds, is commonly used for this purpose. In this paper, we assume that a coherent source is permanently present arriving from an unknown direction of arrivals (DOA). The typical case is the presence of microbaroms or the presence of wind. This source is seen as a nuisance signal (NS). In [4], [3] authors assume that a time cell without the SOI (CH0) is available, whereas a following time cell is considered as the cell under test (CUT). Therefore the DOA and the SNR of the NS can be estimated. If the signal-to-noise ration SNR of the NS is large enough, the distribution of the F-stat under the absence of SOI is known to be a non central Fisher. It follows that the threshold can be performed from a given value of the FAR. The major drawback to keep the NS is that the NS could hide the SOI, this phenomena is similar to the leakage which is a well-known phenomena in the Fourier analysis. An other approach consists to use the DOA estimate of the NS to mitigate the NS by spatial notch filter in the frequency domain. On this approach a new algorithm is provided. To illustrate, numerical results on synthetical and real data are presented, in term of Receiver Operating Characteristic ROC curves. REFERENCES [1] Christie D.R. and Campus P., The IMS infrasound netwrok: design and establishment of infrasound stations, Infrasound Monitoring for Atmospheric Studies, Springer Netherlands, Editor: Le Pichon, Alexis and Blanc, Elisabeth and Hauchecorne, Alain, pp 27-72, 2010. [2] Shumway R. H.,Advances in Mixed Signal Processing for Regional and Teleseismic Arrays 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, pp 503-509, 2007. [3] Park J., Hayward C.T., Zeiler C. P., Arrowsmith S.J. and Stump B.W., A Comparative Study of Automated Infrasound Detectors - PMCC and inframonitor with analyst review, SSA Annual Meeting, 2013. [4] Arrowsmith S.J., Whitaker R., Katz C. and Hayward C., The F-Detector Revisited: An Improved Strategy for Signal Detection at Seismic and Infrasound Arrays, Bulletin of the Seismological Society of America, 2008. [5] Arrowsmith S.J., Whitaker R., Steven R. Taylor, Burlacu R., Stump B.W., Hedlin M.A.H., Randall G., Hayward C. and ReVelle D., Regional monitoring of infrasound events using multiple arrays: application to Utah and Washington State, Geophys. J. Int., vol.175, pp 291-300, 2008. [6] Charbit M., Gaillard P. and Le Pichon A., Evaluating the performance of infrasound detectors, EGU, Vienne, Autriche, April 2012.

Measurements of diurnal variations and eddy covariance (EC) fluxes of glyoxal in the tropical marine boundary layer: description of the Fast LED-CE-DOAS instrument

NASA Astrophysics Data System (ADS)

Coburn, S.; Ortega, I.; Thalman, R.; Blomquist, B.; Fairall, C. W.; Volkamer, R.

2014-10-01

Here we present first eddy covariance (EC) measurements of fluxes of glyoxal, the smallest α-dicarbonyl product of hydrocarbon oxidation, and a precursor for secondary organic aerosol (SOA). The unique physical and chemical properties of glyoxal - i.e., high solubility in water (effective Henry's law constant, KH = 4.2 × 105 M atm-1) and short atmospheric lifetime (~2 h at solar noon) - make it a unique indicator species for organic carbon oxidation in the marine atmosphere. Previous reports of elevated glyoxal over oceans remain unexplained by atmospheric models. Here we describe a Fast Light-Emitting Diode Cavity-Enhanced Differential Optical Absorption Spectroscopy (Fast LED-CE-DOAS) instrument to measure diurnal variations and EC fluxes of glyoxal and inform about its unknown sources. The fast in situ sensor is described, and first results are presented from a cruise deployment over the eastern tropical Pacific Ocean (20° N to 10° S; 133 to 85° W) as part of the Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated VOCs (TORERO) field experiment (January to March 2012). The Fast LED-CE-DOAS is a multispectral sensor that selectively and simultaneously measures glyoxal (CHOCHO), nitrogen dioxide (NO2), oxygen dimers (O4), and water vapor (H2O) with ~2 Hz time resolution (Nyquist frequency ~1 Hz) and a precision of ~40 pptv Hz-0.5 for glyoxal. The instrument is demonstrated to be a "white-noise" sensor suitable for EC flux measurements. Fluxes of glyoxal are calculated, along with fluxes of NO2, H2O, and O4, which are used to aid the interpretation of the glyoxal fluxes. Further, highly sensitive and inherently calibrated glyoxal measurements are obtained from temporal averaging of data (e.g., detection limit smaller than 2.5 pptv in an hour). The campaign average mixing ratio in the Southern Hemisphere (SH) is found to be 43 ± 9 pptv glyoxal, which is higher than the Northern Hemisphere (NH) average of 32 ± 6 pptv (error reflects variability over multiple days). The diurnal variation of glyoxal in the marine boundary layer (MBL) is measured for the first time, and mixing ratios vary by ~8 pptv (NH) and ~12 pptv (SH) over the course of 24 h. Consistently, maxima are observed at sunrise (NH: 35 ± 5 pptv; SH: 47 ± 7 pptv), and minima at dusk (NH: 27 ± 5 pptv; SH: 35 ± 8 pptv). In both hemispheres, the daytime flux was directed from the atmosphere into the ocean, indicating that the ocean is a net sink for glyoxal during the day. After sunset the ocean was a source for glyoxal to the atmosphere (positive flux) in the SH; this primary ocean source was operative throughout the night. In the NH, the nighttime flux was positive only shortly after sunset and negative during most of the night. Positive EC fluxes of soluble glyoxal over oceans indicate the presence of an ocean surface organic microlayer (SML) and locate a glyoxal source within the SML. The origin of most atmospheric glyoxal, and possibly other oxygenated hydrocarbons over tropical oceans, remains unexplained and warrants further investigation.

Validation of WRF-Chem air quality simulations in the Netherlands at high resolution

NASA Astrophysics Data System (ADS)

Hilboll, A.; Lowe, D.; Kuenen, J. J. P.; Denier Van Der Gon, H.; Vrekoussis, M.

2017-12-01

Air pollution is the single most important environmental hazard for publichealth, and especially nitrogen dioxide (NO2) plays a key role in air qualityresearch. With the aim of improving the quality and reproducibility ofmeasurements of NO2 vertical distribution from MAX-DOAS instruments, theCINDI-2 campaign was held in Cabauw (NL) in September 2016.The measurement site was rural, but surrounded by several major pollutioncenters. Due to this spatial heterogeneity of emissions, as well as themeteorological conditions, high spatial and temporal variability in NO2 mixingratios were observed.Air quality models used in the analysis of the measured data must have highspatial resolution in order to resolve this fine spatial structure. Thisremains a challenge even today, mostly due to the uncertainties and largespatial heterogeneity of emission data, and the need to parameterize small-scaleprocesses.In this study, we use the state-of-the-art version 3.9 of the Weather Researchand Forecasting Model with Chemistry (WRF-Chem) to simulate air pollutantconcentrations over the Netherlands, to facilitate the analysis of the CINDI-2NO2 measurements. The model setup contains three nested domains withhorizontal resolutions of 15, 3, and 1 km. Anthropogenic emissions are takenfrom the TNO-MACC III inventory and, where available, from the Dutch PollutantRelease and Transfer Register (Emissieregistratie), at a spatial resolution of 7and 1 km, respectively. We use the Common Reactive Intermediates gas-phasechemical mechanism (CRIv2-R5) with the MOSAIC aerosol module.The high spatial resolution of model and emissions will allow us to resolve thestrong spatial gradients in the NO2 concentrations measured during theCINDI-2 campaign, allowing for an unprecedented level of detail in theanalysis of individual pollution sources.

Satellite-Based Tropospheric NO2 Column Trends in the Last 10 Years Over Mexican Urban Areas Measured by the Ozone Monitoring Instrument

NASA Astrophysics Data System (ADS)

Rivera, C. I.; Stremme, W.; Grutter, M.

2015-12-01

Population density and economic activities in urban agglomerations have drastically increased in many cities in Mexico during the last decade. Several factors are responsible for increased urbanization such as a shift of people from rural to urban areas while looking for better education, services and job opportunities as well as the natural growth of the urban areas themselves. Urbanization can create great social, economic and environmental pressures and changes which can easily be observed in most urban agglomerations in the world. In this study, we have focused on analyzing tropospheric NO2 (nitrogen dioxide) column trends over Mexican urban areas that have a population of at least one million inhabitants according to the latest 2010 population census. Differential Optical Absorption Spectroscopy (DOAS) measurements of NO2 conducted by the space-borne Ozone Monitoring Instrument (OMI) on board the Aura satellite between 2005 and 2014 have been used for this analysis. This dataset has allowed us to obtain a satellite-based 10-year tropospheric NO2 column trend over the most populated Mexican cities which include the dominating metropolitan area of Mexico City with more than twenty million inhabitants as well as ten other Mexican cities with a population ranging between one to five million inhabitants with a wide range of activities (commercial, agricultural or heavily industrialized) as well as two important border crossings. Distribution maps of tropospheric NO2 columns above the studied urban agglomerations were reconstructed from the analyzed OMI dataset, allowing to identify areas of interest due to clear NO2 enhancements inside these urban regions.

Ammonia emissions from a grazed field estimated by miniDOAS measurements and inverse dispersion modelling

NASA Astrophysics Data System (ADS)

Bell, Michael; Flechard, Chris; Fauvel, Yannick; Häni, Christoph; Sintermann, Jörg; Jocher, Markus; Menzi, Harald; Hensen, Arjan; Neftel, Albrecht

2017-05-01

Ammonia (NH3) fluxes were estimated from a field being grazed by dairy cattle during spring by applying a backward Lagrangian stochastic model (bLS) model combined with horizontal concentration gradients measured across the field. Continuous concentration measurements at field boundaries were made by open-path miniDOAS (differential optical absorption spectroscopy) instruments while the cattle were present and for 6 subsequent days. The deposition of emitted NH3 to clean patches on the field was also simulated, allowing both net and gross emission estimates, where the dry deposition velocity (vd) was predicted by a canopy resistance (Rc) model developed from local NH3 flux and meteorological measurements. Estimated emissions peaked during grazing and decreased after the cattle had left the field, while control on emissions was observed from covariance with temperature, wind speed and humidity and wetness measurements made on the field, revealing a diurnal emission profile. Large concentration differences were observed between downwind receptors, due to spatially heterogeneous emission patterns. This was likely caused by uneven cattle distribution and a low grazing density, where hotspots of emissions would arise as the cattle grouped in certain areas, such as around the water trough. The spatial complexity was accounted for by separating the model source area into sub-sections and optimising individual source area coefficients to measured concentrations. The background concentration was the greatest source of uncertainty, and based on a sensitivity/uncertainty analysis the overall uncertainty associated with derived emission factors from this study is at least 30-40 %.Emission factors can be expressed as 6 ± 2 g NH3 cow-1 day-1, or 9 ± 3 % of excreted urine-N emitted as NH3, when deposition is not simulated and 7 ± 2 g NH3 cow-1 day-1, or 10 ± 3 % of excreted urine-N emitted as NH3, when deposition is included in the gross emission model. The results suggest that around 14 ± 4 % of emitted NH3 was deposited to patches within the field that were not affected by urine or dung.

EPIC/DSCOVR's Oxygen Absorption Channels: A Cloud Profiling Information Content Analysis

NASA Astrophysics Data System (ADS)

Davis, A. B.; Merlin, G.; Labonnote, L. C.; Cornet, C.; Dubuisson, P.; Ferlay, N.; Parol, F.; Riedi, J.; Yang, Y.

2016-12-01

EPIC/DSCOVR has several spectral channels dedicated to cloud characterization, most notably O2 A- and B-band. Differential optical absorption spectroscopy (DOAS) ratios of in-band and reference channels are less prone to calibration error than the 4 individual signals. Using these ratios, we have replicated for mono-directional (quasi-backscattering) EPIC observations the recent cloud information content analysis by Merlin et al. (AMT-D,8:12709-12758,2015) that was focused on A-band-only but multi-angle observations by POLDER in the past, by AirMSPI in the present, and by 3MI and MAIA in the future. The methodology is based on extensive forward 1D radiative transfer (RT) computations using the ARTDECO model that implements a k-distribution technique for the absorbing (in-band) channels. These synthetic signals are combined into a Bayesian Rodgers-type framework for estimating posterior uncertainty on retrieved quantities. Recall that this formalism calls explicitly for: (1) estimates of instrument error, and (2) prior uncertainty on the retrieved quantities, to which we add (3) reasonable estimates of uncertainty in the non- or otherwise-retrieved properties. Wide ranges of cloud top heights (CTHs) and cloud geometrical thicknesses (CGTs) are examined for a representative selection of cloud optical thicknesses (COTs), solar angles, and surface reflectances. We found that CTH should be reliably retrieved from EPIC data under most circumstances as long as COT can be inferred from non-absorbing channels, and the bias from in-cloud absorption is removed. However, CGT will be hard to determine unless CTH is constrained by independent means. EPIC has several UV channels that could be brought to bear. These findings conflict those of Yang et al. (JQSRT,122:141-149,2013), so we also revisit that more preliminary study that did not account for a realistic level of residual instrument noise in the DOAS ratios. In conclusion, we believe that the present information content analysis will inform the EPIC/DSCOVR Level 2 algorithm development team about what cloud properties to target using the A/B-band channels, depending on the availability of other cloud information.

Long open-path measurements of greenhouse gases in air using near-infrared Fourier transform spectroscopy

NASA Astrophysics Data System (ADS)

Griffith, David W. T.; Pöhler, Denis; Schmitt, Stefan; Hammer, Samuel; Vardag, Sanam N.; Platt, Ulrich

2018-03-01

In complex and urban environments, atmospheric trace gas composition is highly variable in time and space. Point measurement techniques for trace gases with in situ instruments are well established and accurate, but do not provide spatial averaging to compare against developing high-resolution atmospheric models of composition and meteorology with resolutions of the order of a kilometre. Open-path measurement techniques provide path average concentrations and spatial averaging which, if sufficiently accurate, may be better suited to assessment and interpretation with such models. Open-path Fourier transform spectroscopy (FTS) in the mid-infrared region, and differential optical absorption spectroscopy (DOAS) in the UV and visible, have been used for many years for open-path spectroscopic measurements of selected species in both clean air and in polluted environments. Near infrared instrumentation allows measurements over longer paths than mid-infrared FTS for species such as greenhouse gases which are not easily accessible to DOAS.In this pilot study we present the first open-path near-infrared (4000-10 000 cm-1, 1.0-2.5 µm) FTS measurements of CO2, CH4, O2, H2O and HDO over a 1.5 km path in urban Heidelberg, Germany. We describe the construction of the open-path FTS system, the analysis of the collected spectra, several measures of precision and accuracy of the measurements, and the results a four-month trial measurement period in July-November 2014. The open-path measurements are compared to calibrated in situ measurements made at one end of the open path. We observe significant differences of the order of a few ppm for CO2 and a few tens of ppb for CH4 between the open-path and point measurements which are 2 to 4 times the measurement repeatability, but we cannot unequivocally assign the differences to specific local sources or sinks. We conclude that open-path FTS may provide a valuable new tool for investigations of atmospheric trace gas composition in complex, small-scale environments such as cities.

Aircraft-borne DOAS limb observations of iodine monoxide around Borneo

NASA Astrophysics Data System (ADS)

Großmann, Katja; Hossaini, Ryan; Mantle, Hannah; Chipperfield, Martyn; Wittrock, Folkard; Peters, Enno; Lampel, Johannes; Walker, Hannah; Heard, Dwayne; Krystofiak, Gisèle; Catoire, Valéry; Dorf, Marcel; Werner, Bodo; Pfeilsticker, Klaus

2015-04-01

Iodine monoxide (IO) has a major impact on the photochemistry of the troposphere. It can for example catalytically destroy ozone, influence the atmospheric oxidation capacity by changing the partitioning of the HOx and NOx species, or contribute to the formation of ultrafine particles. Information regarding the vertical distribution of IO is still sparse since only few vertical profiles of IO exist for the troposphere. Spectroscopic measurements were carried out from aboard the research aircraft DLR-Falcon during the SHIVA (Stratospheric ozone: Halogen Impacts in a Varying Atmosphere) campaign at Malaysian Borneo in November and December 2011 to study the abundance and transport of trace gases in the lower atmosphere. Sixteen research flights were performed covering legs near the surface in the marine boundary layer (MBL) as well as in the free troposphere (FT) up to an altitude of 13 km. The spectroscopic measurements were evaluated using the Differential Optical Absorption Spectroscopy (DOAS) technique in limb geometry, which supports observations of UV/visible absorbing trace gases, such as O4, BrO, IO, NO2, HCHO, CHOCHO, HONO and H2O, and altitude information was gained via the O4 scaling technique and/or full inversion. The inferred vertical profiles of IO showed mixing ratios of 0.5-1.5 ppt in the MBL, which decreased to 0.1-0.3 ppt in the FT. Occasionally, the IO observed in the FT of the marine environment coincided with elevated amounts of CO, but no IO was observed over land, neither in the boundary layer, nor in the FT. This behavior strongly indicated that the major sources for IO were organic and inorganic precursor molecules emitted from the ocean, which during daytime rapidly formed a sizable amount of IO in the MBL that was occasionally transported into the FT where efficient loss processes for IO must exist. The inferred vertical profiles of IO are compared to simulations using the global 3-D chemistry transport model TOMCAT including recent fluxes of HOI and I2 to examine possible sinks of iodine.

Measurements of Isoprene and its Oxidation Products during the CLOUD9 Experiment

NASA Astrophysics Data System (ADS)

Bernhammer, Anne-Kathrin; Breitenlechner, Martin; Coburn, Sean; Volkamer, Rainer; Hansel, Armin

2015-04-01

Isoprene (C5H8), being produced and emitted by the biosphere, is by far the dominant biogenic volatile organic compound (BVOC) in the atmosphere. Its complex reaction pathways with OH radicals, O3 and NO3, lead to compounds with lower volatilities and increasing water solubility. The high hydrophilicity allows for easy partitioning between the gas and liquid phase making those compounds good candidates for aqueous phase droplet chemistry that may contribute to particle growth. (Ervens et al., 2008). The CLOUD experiment (Cosmics Leaving Outdoor Droplets) at CERN allows the studying the evolution of particles originating from precursor gases in, in our case isoprene, in an ultraclean and very well controlled environmental chamber. Gas phase concentrations of isoprene and its first reaction products were measured in real-time with a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS, Graus et al., 2010) and Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS, Thalman and Volkamer, 2010). PTR-ToF-MS was calibrated using gas standards with known VOC concentrations. The PTR-ToF-MS was operated with H3O+ and NO+ as primary ions, continuously switching between both operating modes throughout the experiments. The use of different primary ions allows the discrimination of isomeric compounds like the main high NOx oxidation products methyl vinyl ketone (MVK) and methacroleine (MACR). The experiment was conducted at high isoprene concentrations and a constant level of O3. The highly water soluble gas phase oxidation products from the reaction of isoprene with O3 and OH radicals (from isoprene ozonolysis) were investigated and compared for two temperatures (+10 °C and -10 °C) and different NOx concentrations during cloud formation experiments. Here we will present first results of isoprene oxidation products observed with PTR-ToF-MS and CE-DOAS. References Ervens et al. (2008), Geophys. Res. Lett., 35, L02816 Graus et al. (2010), J. Am. Soc. Mass. Spectrom., 21, 1037-1044 Thalman and Volkamer (2010), Atmos. Meas. Tech., 3(6), 2681-2721.

HCHO and NO2 MAXDOAS retrieval strategies harmonization: Recent results from the EU FP7 project QA4ECV

NASA Astrophysics Data System (ADS)

Pinardi, Gaia; Peters, Enno; Hendrick, François; Gielen, Clio; Van Roozendael, Michel; Richter, Andreas; Piters, Ankie; Wagner, Thomas; Wang, Yang; Drosoglou, Theano; Bais, Alkis; Wang, Shanshan; Saiz-Lopez, Alfonso

2016-04-01

During the last decade, it has been extensively demonstrated that MAXDOAS is a useful and reliable technique to retrieve integrated column amounts of tropospheric trace gases and aerosols, as well as information on their vertical distributions. Since it is based on optical remote-sensing in the UV-visible region like nadir backscatter space-borne sensors, MAXDOAS is also increasingly recognized as a reference technique for validating satellite nadir observations of air quality species like NO2 and HCHO. However, building up an harmonized network of MAXDOAS spectrometers requires significant efforts in terms of common retrieval strategies and best-practices definitions. Within the EU FP7 project QA4ECV (Quality Assurance for Essential Climate Variables; see http://www.qa4ecv.eu/), harmonization activities have been initiated focusing on the two main steps of the MAXDOAS retrieval, i.e. the DOAS spectral fit providing the so-called differential slant column densities (DSCDs) and the conversion of the retrieved DSCDs to vertical profiles and/or vertical column densities (VCDs). Regarding the first step, the DOAS settings for HCHO and NO2 are optimized through an intercomparison exercise of slant column retrievals involving 15 groups of the MAXDOAS community including the QA4ECV partners, and based on the radiance spectra acquired during the MAD-CAT campaign held in Mainz (Germany) in June-July 2013 (see http://joseba.mpch-mainz.mpg.de/mad_cat.htm). The harmonization of the second step is done through the application of an AMF (aim mass factor) look-up table (LUT) approach on the optimized NO2 and HCHO DSCDs. The AMF LUTs depend on entry parameters like SZA, elevation and relative azimuth angles, wavelength, boundary layer height, AOD, and surface albedo. The advantages and drawbacks of the LUT approach are illustrated at several stations through comparison of the derived VCDs with those retrieved using the more sophisticated Optimal-Estimation-based profiling method. Recommendations for both MAXDOAS retrieval steps will be given in conclusion.

Are prehospital deaths from trauma and accidental injury preventable? A direct historical comparison to assess what has changed in two decades.

PubMed

Oliver, G J; Walter, D P; Redmond, A D

2017-05-01

In 1994, Hussain and Redmond revealed that up to 39% of prehospital deaths from accidental injury might have been preventable had basic first aid care been given. Since then there have been significant advances in trauma systems and care. The exclusion of prehospital deaths from the analysis of trauma registries, giv en the high rate of those, is a major limitation in prehospital research on preventable death. We have repeated the 1994 study to identify any changes over the years and potential developments to improve patient outcomes. We examined the full Coroner's inquest files for prehospital deaths from trauma and accidental injury over a three-year period in Cheshire. Injuries were scored using the Abbreviated-Injury-Scale (AIS-1990) and Injury Severity Score (ISS), and probability of survival estimated using Bull's probits to match the original protocol. One hundred and thirty-four deaths met our inclusion criteria; 79% were male, average age at death was 53.6 years. Sixty-two were found dead (FD), fifty-eight died at scene (DAS) and fourteen were dead on arrival at hospital (DOA). The predominant mechanism of injury was fall (39%). The median ISS was 29 with 58 deaths (43%) having probability of survival of >50%. Post-mortem evidence of head injury was present in 102 (76%) deaths. A bystander was on scene or present immediately after injury in 45% of cases and prior to the Emergency Medical Services (EMS) in 96%. In 93% of cases a bystander made the call for assistance, in those DAS or DOA, bystander intervention of any kind was 43%. The number of potentially preventable prehospital deaths remains high and unchanged. First aid intervention of any kind is infrequent. There is a potentially missed window of opportunity for bystander intervention prior to the arrival of the ambulance service, with simple first-aid manoeuvres to open the airway, preventing hypoxic brain injury and cardiac arrest. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Mapping of the Tropospheric NO2 Spatial Distribution at City-scale Based on Airborne APEX Hyperspectral Imaging

NASA Astrophysics Data System (ADS)

Tack, F. M.; Merlaud, A.; Danckaert, T.; Yu, H.; Fayt, C.; Iordache, D.; Meuleman, K.; Fierens, F.; Deutsch, F.; Van Roozendael, M.

2016-12-01

NO2 is a key pollutant with highly variable concentrations in space and time. Quantitative information about its spatial variability at high resolution is currently scarce, but very valuable for (air quality) studies at the urban scale. APEX is a pushbroom hyperspectral imager with high spatial (60 by 80 m2) and spectral (2.8-3.3 nm) resolution. APEX flights were conducted over (1) the city and port of Antwerp, Belgium on April 14, 2015 and July 19, 2016, (2) Brussels, Belgium on June 30, 2015 (BUMBA project), and (3) Berlin, Germany on April 21, 2016 (AROMAT and AROMAPEX projects). APEX was operated from a DLR DO-228 plane at 6.1 km altitude. Over Berlin, two additional imagers, AirMAP (IUP Bremen) and SWING (BIRA-IASB), were simultaneously operated from a FUB Cessna at 3 km for intercomparison purposes. NO2 vertical column densities (VCDs) are retrieved based on (1) the DOAS analysis of the observed spectra in the visible region (470 nm - 510 nm), and (2) air mass factor calculations with the RTM VLIDORT 2.6. Results show that APEX is suitable (1) to detect the fast varying spectral signatures of a trace gas like NO2 and (2) to identify small scale gradients in the NO2 field and to resolve individual emission sources. Main NOx sources in the Antwerp area are related to (petro)chemical industry, while traffic emissions are dominant in Brussels. Over Berlin, 2 large industrial NO2 plumes are detected by all three imaging systems, crossing the city from west to east. The NO2 VCD levels range between 0.2 and 3.5 x 1016 molec cm-2. The typical detection limit for the APEX instrument is around 1.7 to 2.2 x 1015 molec cm-2. Correlation coefficients of 0.85 and slopes close to unity are obtained when compared to coincident car mobile-DOAS measurements. The NO2 retrieval algorithm, campaign results, and ongoing research concerning the comparison of the VCDs with in-situ surface concentrations and a high resolution (25 m) air quality model, i.e. RIO-IFDM, will be discussed.

Characterization of potential EC flux underestimation of "sticky" trace gas species

NASA Astrophysics Data System (ADS)

Neftel, Albrecht; Hensen, Arjan; Ibrom, Andreas; Ammann, Christof; Voglmeier, Karl; Brümmer, Christian

2017-04-01

Eddy covariance (EC) flux measurements of "sticky" trace gas species are affected of damping of high frequency variations of the gas concentration. Several approaches have been developed to correct for this effect (see e.g. Ibrom et al., 2007, Ammann et al., 2006). These approaches have in common that the spectral properties of the scalar are compared with the sonic temperature deduced from the Sonic anemometer data that is only marginally damped. A main difference between the two method is that one uses power spectra, while the other is based on co-spectra of the gas concentration with the vertical wind speed. NH3 fluxes used in the analysis stem from two field experiments: a) Posieux intercomparison October 2015: NH3 emissions of a grazed pasture measured with Eddy Covariance using an Aerodyne quantum cascade laser and with a horizontal gradient measurement using MiniDOAS systems (Sintermann et al., 2016) in conjunction with a dispersion model. b) Dronten experiment June 2016 in the Netherlands: NH3 emissions from two manured circles within 40m diameters have been determined with four different approaches (Eddy Covariance, Integrated Horizontal Flux approach, horizontal gradients and plume measurements). Despite correction with standard methods, turbulent NH3 flux measurements with the eddy covariance method seem still be underestimated when, e.g., compared to flux estimated using gradient methods. We discuss possible correction algorithms and how such underestimations can be recognized in the usual case, where no alternative flux estimation methods are available. References: Ammann, C., Brunner, A., Spirig, C., and Neftel, A. 2006: Technical note: Water vapour concentration and flux measurements with PTR-MS, Atmos. Chem. Phys., 6, 4643-4651 Ibrom, A., Dellwik, E., Jensen, N.O., Flyvbjerg, H. and Pilegaard, K., 2007. Strong low-pass filtering effects on water vapour flux measurements with closed-path eddy correlation systems. Agricultural and Forest Meteorology, 147: 140 -156. Sintermann, J., Dietrich, K., Hani, C., Bell, M., Jocher, M., and Neftel, A. 2016 A miniDOAS instrument optimised for ammonia field measurements, Atmos Meas Tech, 9, 2721-2734

Compressed Symmetric Nested Arrays and Their Application for Direction-of-Arrival Estimation of Near-Field Sources.

PubMed

Li, Shuang; Xie, Dongfeng

2016-11-17

In this paper, a new sensor array geometry, called a compressed symmetric nested array (CSNA), is designed to increase the degrees of freedom in the near field. As its name suggests, a CSNA is constructed by getting rid of some elements from two identical nested arrays. The closed form expressions are also presented for the sensor locations and the largest degrees of freedom obtainable as a function of the total number of sensors. Furthermore, a novel DOA estimation method is proposed by utilizing the CSNA in the near field. By employing this new array geometry, our method can identify more sources than sensors. Compared with other existing methods, the proposed method achieves higher resolution because of increased array aperture. Simulation results are demonstrated to verify the effectiveness of the proposed method.

Description of five species of Xanthopimpla Saussure 1892 (Hymenoptera: Ichneumonidae: Pimplinae) from Malaysia

NASA Astrophysics Data System (ADS)

Dass, Angeline David; Ghani, Idris Abd.

2013-11-01

Description of five species of Xanthopimpla Saussure, 1829 (Hymenoptera: Ichneumonidae: Pimplinae) from Malaysia was done using specimens deposited in Centre for Insects Systematics, Universiti Kebangsaan Malaysia (CIS, UKM). Type and non-type specimens were loaned from several repositories namely Zoological Museum of Amsterdam Netherlands (ZMAN), Swedish Museum of Natural History (NRM), British Natural History Museum London (BMNH) and Department of Agricultural Malaysia (DOA) for identification and comparison. The specimens were identified to the species level which gives rise to five species namely Xanthopimpla conica Cushman, 1925, Xanthopimpla despinosa leipephelis Townes & Chiu, 1970, Xanthopimpla flavolineata Cameron, 1907, Xanthopimpla punctata (Fabricius, 1781) and Xanthopimpla tricapus impressa Townes & Chiu, 1970. A dichotomous key and descriptions for five Xanthopimpla spesies were provided. Photos and illustrations of carina on propodeum were also included in this paper.

A mobile system for active otpical pollution monitoring

NASA Technical Reports Server (NTRS)

Sunesson, A.; Edner, H.; Svanberg, S.; Uneus, L.; Wendt, W.; Fredriksson, K.

1986-01-01

The remote monitoring of atmospheric pollutants can now be performed in several ways. Laser radar techniques have proven their ability to reveal the spatial distribution of different species or particles. Classical optical techniques can also be used, but yield the average concentration over a given path and hence no range resolution. One such technique is Differential Optical Absorption Spectroscopy, DOAS. Such schemes can be used to monitor paths that a preliminary lidar investigation has shown to be of interest. Having previously had access to a mobile lidar system, a new system has been completed. The construction builds on experience from using the other system and it is meant to be more of a mobile optical laboratory than just a lidar system. A complete system description is given along with some preliminary usage. Future uses are contemplated.

Estimating the domain of applicability for machine learning QSAR models: a study on aqueous solubility of drug discovery molecules.

PubMed

Schroeter, Timon Sebastian; Schwaighofer, Anton; Mika, Sebastian; Ter Laak, Antonius; Suelzle, Detlev; Ganzer, Ursula; Heinrich, Nikolaus; Müller, Klaus-Robert

2007-12-01

We investigate the use of different Machine Learning methods to construct models for aqueous solubility. Models are based on about 4000 compounds, including an in-house set of 632 drug discovery molecules of Bayer Schering Pharma. For each method, we also consider an appropriate method to obtain error bars, in order to estimate the domain of applicability (DOA) for each model. Here, we investigate error bars from a Bayesian model (Gaussian Process (GP)), an ensemble based approach (Random Forest), and approaches based on the Mahalanobis distance to training data (for Support Vector Machine and Ridge Regression models). We evaluate all approaches in terms of their prediction accuracy (in cross-validation, and on an external validation set of 536 molecules) and in how far the individual error bars can faithfully represent the actual prediction error.

Estimating the domain of applicability for machine learning QSAR models: a study on aqueous solubility of drug discovery molecules.

PubMed

Schroeter, Timon Sebastian; Schwaighofer, Anton; Mika, Sebastian; Ter Laak, Antonius; Suelzle, Detlev; Ganzer, Ursula; Heinrich, Nikolaus; Müller, Klaus-Robert

2007-09-01

We investigate the use of different Machine Learning methods to construct models for aqueous solubility. Models are based on about 4000 compounds, including an in-house set of 632 drug discovery molecules of Bayer Schering Pharma. For each method, we also consider an appropriate method to obtain error bars, in order to estimate the domain of applicability (DOA) for each model. Here, we investigate error bars from a Bayesian model (Gaussian Process (GP)), an ensemble based approach (Random Forest), and approaches based on the Mahalanobis distance to training data (for Support Vector Machine and Ridge Regression models). We evaluate all approaches in terms of their prediction accuracy (in cross-validation, and on an external validation set of 536 molecules) and in how far the individual error bars can faithfully represent the actual prediction error.

Feedback Robust Cubature Kalman Filter for Target Tracking Using an Angle Sensor.

PubMed

Wu, Hao; Chen, Shuxin; Yang, Binfeng; Chen, Kun

2016-05-09

The direction of arrival (DOA) tracking problem based on an angle sensor is an important topic in many fields. In this paper, a nonlinear filter named the feedback M-estimation based robust cubature Kalman filter (FMR-CKF) is proposed to deal with measurement outliers from the angle sensor. The filter designs a new equivalent weight function with the Mahalanobis distance to combine the cubature Kalman filter (CKF) with the M-estimation method. Moreover, by embedding a feedback strategy which consists of a splitting and merging procedure, the proper sub-filter (the standard CKF or the robust CKF) can be chosen in each time index. Hence, the probability of the outliers' misjudgment can be reduced. Numerical experiments show that the FMR-CKF performs better than the CKF and conventional robust filters in terms of accuracy and robustness with good computational efficiency. Additionally, the filter can be extended to the nonlinear applications using other types of sensors.

Estimating the domain of applicability for machine learning QSAR models: a study on aqueous solubility of drug discovery molecules

NASA Astrophysics Data System (ADS)

Schroeter, Timon Sebastian; Schwaighofer, Anton; Mika, Sebastian; Ter Laak, Antonius; Suelzle, Detlev; Ganzer, Ursula; Heinrich, Nikolaus; Müller, Klaus-Robert

2007-12-01

We investigate the use of different Machine Learning methods to construct models for aqueous solubility. Models are based on about 4000 compounds, including an in-house set of 632 drug discovery molecules of Bayer Schering Pharma. For each method, we also consider an appropriate method to obtain error bars, in order to estimate the domain of applicability (DOA) for each model. Here, we investigate error bars from a Bayesian model (Gaussian Process (GP)), an ensemble based approach (Random Forest), and approaches based on the Mahalanobis distance to training data (for Support Vector Machine and Ridge Regression models). We evaluate all approaches in terms of their prediction accuracy (in cross-validation, and on an external validation set of 536 molecules) and in how far the individual error bars can faithfully represent the actual prediction error.

Estimating the domain of applicability for machine learning QSAR models: a study on aqueous solubility of drug discovery molecules

NASA Astrophysics Data System (ADS)

Schroeter, Timon Sebastian; Schwaighofer, Anton; Mika, Sebastian; Ter Laak, Antonius; Suelzle, Detlev; Ganzer, Ursula; Heinrich, Nikolaus; Müller, Klaus-Robert

2007-09-01

We investigate the use of different Machine Learning methods to construct models for aqueous solubility. Models are based on about 4000 compounds, including an in-house set of 632 drug discovery molecules of Bayer Schering Pharma. For each method, we also consider an appropriate method to obtain error bars, in order to estimate the domain of applicability (DOA) for each model. Here, we investigate error bars from a Bayesian model (Gaussian Process (GP)), an ensemble based approach (Random Forest), and approaches based on the Mahalanobis distance to training data (for Support Vector Machine and Ridge Regression models). We evaluate all approaches in terms of their prediction accuracy (in cross-validation, and on an external validation set of 536 molecules) and in how far the individual error bars can faithfully represent the actual prediction error.

Therapeutic Symptomatic Strategies in the Parasomnias.

PubMed

Manni, Raffaele; Toscano, Gianpaolo; Terzaghi, Michele

2018-06-05

The purpose of this review was to discuss the currently available pharmacologic and non-pharmacologic treatment options for parasomnias. Recent pathophysiological findings about sleep structure in parasomnias helped understanding several drug mechanisms of action. Serotoninergic theory accounts for the effect of serotoninergic drugs. Study about spectral analysis of sleep showed the effect of clonazepam on spectral bands. Cannabinoids proved to be effective in some of parasomnias, as in many other neurological disorders. A series of therapeutic strategies were analyzed and compared. Benzodiazepines, antidepressant drugs, and L-5-hydroxytryptophan may be beneficial in DOA. SSRI and topiramate are effective in SRED. RBD responds to clonazepam, melatonin, and to a lesser extent to dopaminergic and anticholinergic agents. Prazosin and cannabinoids are effective in nightmare disorder. Sleep paralysis may respond to antidepressant agents. Tricyclic antidepressant may be effective in sleep-related hallucinations and exploding head syndrome. Sleep enuresis may be successfully treated with desmopressin, anticholinergic drugs, and imipramine.

Evaluation of improved operational standard tropospheric NO2 retrievals from Ozone Monitoring Instrument using in situ and surface-based NO2 observations

NASA Astrophysics Data System (ADS)

Celarier, E. A.; Lamsal, L.; Krotkov, N. A.; Bucsela, E. J.; Herman, J. R.; Dickerson, R. R.; He, H.; Brent, L. C.; Retscher, C.; Swartz, W. H.; Gleason, J. F.

2011-12-01

Nitrogen oxides are key actors in air quality and climate change. Column observations of tropospheric NO2 from the nadir-veiwing satellite sensors have been widely used to understand sources and chemistry of NOx. We have implemented several improvements to the operational algorithm developed at NASA GSFC and retrieved tropospheric NO2. Here we evaluate the new product using in situ surface measurements at the SEARCH, AQS/EPA, and NAPS networks, in situ aircraft (DISCOVER-AQ and RAMMPP), and ground-based PANDORA and DOAS measurements. The agreement among these data is within the uncertainty of measurements. The new OMI tropospheric NO2 product available at high spatial resolution is valuable to evaluate chemical transport models, to examine spatial and temporal pattern of NOx emissions, to provide top-down constraints to surface NOx emissions, and to estimate NOx lifetimes.

Adaptive Sparse Representation for Source Localization with Gain/Phase Errors

PubMed Central

Sun, Ke; Liu, Yimin; Meng, Huadong; Wang, Xiqin

2011-01-01

Sparse representation (SR) algorithms can be implemented for high-resolution direction of arrival (DOA) estimation. Additionally, SR can effectively separate the coherent signal sources because the spectrum estimation is based on the optimization technique, such as the L1 norm minimization, but not on subspace orthogonality. However, in the actual source localization scenario, an unknown gain/phase error between the array sensors is inevitable. Due to this nonideal factor, the predefined overcomplete basis mismatches the actual array manifold so that the estimation performance is degraded in SR. In this paper, an adaptive SR algorithm is proposed to improve the robustness with respect to the gain/phase error, where the overcomplete basis is dynamically adjusted using multiple snapshots and the sparse solution is adaptively acquired to match with the actual scenario. The simulation results demonstrate the estimation robustness to the gain/phase error using the proposed method. PMID:22163875

Trend and variability of atmospheric ozone over middle Indo-Gangetic Plain: impacts of seasonality and precursor gases.

PubMed

Shukla, K; Srivastava, Prashant K; Banerjee, T; Aneja, Viney P

2017-01-01

Ozone dynamics in two urban background atmospheres over middle Indo-Gangetic Plain (IGP) were studied in two contexts: total columnar and ground-level ozone. In terms of total columnar ozone (TCO), emphases were made to compare satellite-based retrieval with ground-based observation and existing trend in decadal and seasonal variation was also identified. Both satellite-retrieved (Aura Ozone Monitoring Instrument-Differential Optical Absorption Spectroscopy (OMI-DOAS)) and ground-based observations (IMD-O 3 ) revealed satisfying agreement with OMI-DOAS observation over predicting TCO with a positive bias of 7.24 % under all-sky conditions. Minor variation between daily daytime (r = 0.54; R 2  = 29 %; n = 275) and satellite overpass time-averaged TCO (r = 0.58; R 2  = 34 %; n = 208) was also recognized. A consistent and clear seasonal trend in columnar ozone (2005-2015) was noted with summertime (March-June) maxima (Varanasi, 290.9 ± 8.8; Lucknow, 295.6 ± 9.5 DU) and wintertime (December-February) minima (Varanasi, 257.4 ± 10.1; Lucknow, 258.8 ± 8.8 DU). Seasonal trend decomposition based on locally weighted regression smoothing technique identified marginally decreasing trend (Varanasi, 0.0084; Lucknow, 0.0096 DU year -1 ) especially due to reduction in monsoon time minima and summertime maxima. In continuation to TCO, variation in ground-level ozone in terms of seasonality and precursor gases were also analysed from September 2014 to August 2015. Both stations registered similar pattern of variation with Lucknow representing slightly higher annual mean (44.3 ± 30.6; range, 1.5-309.1 μg/m 3 ) over Varanasi (38.5 ± 17.7; range, 4.9-104.2 μg/m 3 ). Variation in ground-level ozone was further explained in terms water vapour, atmospheric boundary layer height and solar radiation. Ambient water vapour content was found to associate negatively (r = -0.28, n = 284) with ground-level ozone with considerable seasonal variation in Varanasi. Implication of solar radiation on formation of ground-level ozone was overall positive (Varanasi, 0.60; Lucknow, 0.26), while season-specific association was recorded in case of atmospheric boundary layer.

Built Heritage Documentation and Management: AN Integrated Conservation Approach in Bagan

NASA Astrophysics Data System (ADS)

Mezzino, D.; Chan, L.; Santana Quintero, M.; Esponda, M.; Lee, S.; Min, A.; Pwint, M.

2017-08-01

Good practices in heritage conservation are based on accurate information about conditions, materials, and transformation of built heritage sites. Therefore, heritage site documentation and its analysis are essential parts for their conservation. In addition, the devastating effects of recent catastrophic events in different geographical areas have highly affected cultural heritage places. Such areas include and are not limited to South Europe, South East Asia, and Central America. Within this framework, appropriate acquisition of information can effectively provide tools for the decision-making process and management. Heritage documentation is growing in innovation, providing dynamic opportunities for effectively responding to the alarming rate of destruction by natural events, conflicts, and negligence. In line with these considerations, a multidisciplinary team - including students and faculty members from Carleton University and Yangon Technological University, as well as staff from the Department of Archaeology, National Museum and Library (DoA) and professionals from the CyArk foundation - developed a coordinated strategy to document four temples in the site of Bagan (Myanmar). On-field work included capacity-building activities to train local emerging professionals in the heritage field (graduate and undergraduate students from the Yangon Technological University) and to increase the technical knowledge of the local DoA staff in the digital documentation field. Due to the short time of the on-field activity and the need to record several monuments, a variety of documentation techniques, including image and non-image based ones, were used. Afterwards, the information acquired during the fieldwork was processed to develop a solid base for the conservation and monitoring of the four documented temples. The relevance of developing this kind of documentation in Bagan is related to the vulnerability of the site, often affected by natural seismic events and flooding, as well as the lack of maintenance. Bagan provided an excellent case study to test the effectiveness of the proposed approach, to prevent and manage the damages of catastrophic events, and to support retrofitting actions. In order to test the flexibility of adopted methodology and workflow, temples with different features - in terms of architectural design, shape, and geometry - were selected. The goals of these documentation activities range from testing digital documentation workflows for the metric and visual recording of the site (reviewing strengths and limitations of particular recording techniques), to the definition of effective conditions assessment strategies.

Impact of sulfur content regulations of shipping fuel on coastal air quality

NASA Astrophysics Data System (ADS)

Seyler, André; Wittrock, Folkard; Kattner, Lisa; Mathieu-Üffing, Barbara; Weigelt, Andreas; Peters, Enno; Richter, Andreas; Schmolke, Stefan; Burrows, John P.

2016-04-01

Shipping traffic is a sector that faces an enormous growth rate and contributes substantially to the emissions from the transportation sector, but lacks regulations and controls. Shipping is not enclosed in the Kyoto Protocol. However, the International Maritime Organization (IMO) introduced sufhur limits for marine heavy fuels, nitrogen oxide limits for newly-built ship engines and established Emission Control Areas (ECA) in the North and Baltic Sea as well as around North America with the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78 Annex VI). Recently, on the 1st of January 2015, the allowed sulfur content of marine fuels inside Sulfur Emission Control Areas has been significantly decreased from 1.0% to 0.1%. However, measurements of reactive trace gases and the chemical composition of the marine troposphere along shipping routes are sparse and up to now there is no regular monitoring system available. The project MeSmarT (measurements of shipping emissions in the marine troposphere) is a cooperation between the University of Bremen, the German Federal Maritime and Hydrographic Agency (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and the Helmholtz-Zentrum Geesthacht. This study aims to analyse the influence of shipping emissions on the coastal air quality by evaluating ground-based remote sensing measurements using the MAX-DOAS (Multi AXis Differential Optical Absorption Spectroscopy) technique. Measurements of the atmospheric trace gases nitrogen dioxide (NO2) and sulfur dioxide (SO2) have been carried out in the marine troposphere at the MeSmarT measurement sites in Wedel and on Neuwerk and on-board several ship cruises on the North and Baltic Sea. The capability of two-channel MAX-DOAS systems to do simultaneous measurements in the UV and visible spectral range has been used in the so called "onion-peeling" approach to derive spatial distributions of ship emissions and to analyse the movement of the exhausted plumes. Long term time evolutions have been evaluated to show the impact of recent sulfur emission regulations on the measured SO2 pollution levels. In 2015, a significant decrease of SO2 emissions has been found compared to the years before. This shows that the new, more restrictive fuel sulfur content limits lead to a clear improvement in coastal air quality.

Horizontal and vertical structure of reactive bromine events probed by bromine monoxide MAX-DOAS

NASA Astrophysics Data System (ADS)

Simpson, William R.; Peterson, Peter K.; Frieß, Udo; Sihler, Holger; Lampel, Johannes; Platt, Ulrich; Moore, Chris; Pratt, Kerri; Shepson, Paul; Halfacre, John; Nghiem, Son V.

2017-08-01

Heterogeneous photochemistry converts bromide (Br-) to reactive bromine species (Br atoms and bromine monoxide, BrO) that dominate Arctic springtime chemistry. This phenomenon has many impacts such as boundary-layer ozone depletion, mercury oxidation and deposition, and modification of the fate of hydrocarbon species. To study environmental controls on reactive bromine events, the BRomine, Ozone, and Mercury EXperiment (BROMEX) was carried out from early March to mid-April 2012 near Barrow (Utqiaġvik), Alaska. We measured horizontal and vertical gradients in BrO with multiple-axis differential optical absorption spectroscopy (MAX-DOAS) instrumentation at three sites, two mobile and one fixed. During the campaign, a large crack in the sea ice (an open lead) formed pushing one instrument package ˜ 250 km downwind from Barrow (Utqiaġvik). Convection associated with the open lead converted the BrO vertical structure from a surface-based event to a lofted event downwind of the lead influence. The column abundance of BrO downwind of the re-freezing lead was comparable to upwind amounts, indicating direct reactions on frost flowers or open seawater was not a major reactive bromine source. When these three sites were separated by ˜ 30 km length scales of unbroken sea ice, the BrO amount and vertical distributions were highly correlated for most of the time, indicating the horizontal length scales of BrO events were typically larger than ˜ 30 km in the absence of sea ice features. Although BrO amount and vertical distribution were similar between sites most of the time, rapid changes in BrO with edges significantly smaller than this ˜ 30 km length scale episodically transported between the sites, indicating BrO events were large but with sharp edge contrasts. BrO was often found in shallow layers that recycled reactive bromine via heterogeneous reactions on snowpack. Episodically, these surface-based events propagated aloft when aerosol extinction was higher (> 0.1 km-1); however, the presence of aerosol particles aloft was not sufficient to produce BrO aloft. Highly depleted ozone (< 1 nmol mol-1) repartitioned reactive bromine away from BrO and drove BrO events aloft in cases. This work demonstrates the interplay between atmospheric mixing and heterogeneous chemistry that affects the vertical structure and horizontal extent of reactive bromine events.

A Tale of Two Cities - HSI-DOAS Measurements of Air Quality

NASA Astrophysics Data System (ADS)

Graves, Rosemarie; Leigh, Roland; Anand, Jasdeep; McNally, Michael; Lawrence, James; Monks, Paul

2013-04-01

Differential Optical Absorption Spectroscopy is now commonly used as an air quality measuring system; primarily through the measurements of nitrogen dioxide (NO2) both as a ground-based and satellite technique. CityScan is a Hemispherical Scanning Imaging Differential Optical Absorption Spectrometer (HSI-DOAS) which has been optimised to measure concentrations of nitrogen dioxide. CityScan has a 95˚ field of view (FOV) between the zenith and 5˚ below the horizon. Across this FOV there are 128 resolved elements which are measured concurrently, the spectrometer is rotated azimuthally 1˚ per second providing full hemispherical coverage every 6 minutes. CityScan measures concentrations of nitrogen dioxide over specific lines of sight and due to the extensive field of view of the instrument this produces measurements which are representative over city-wide scales. Nitrogen dioxide is an important air pollutant which is produced in all combustion processes and can reduce lung function; especially in sensitised individuals. These instruments aim to bridge the gap in spatial scales between point source measurements of air quality and satellite measurements of air quality offering additional information on emissions, transport and the chemistry of nitrogen dioxide. More information regarding the CityScan technique can be found at http://www.leos.le.ac.uk/aq/index.html. CityScan has been deployed in both London and Bologna, Italy during 2012. The London deployment took place as part of the large NERC funded ClearfLo project in January and July/August. CityScan was deployed in Bologna in June as part of the large EU project PEGASOS. Analysis of both of these campaigns of data will be used to give unprecedented levels of spatial information to air quality measurements whilst also showing the difference in air quality between a relatively isolated mega city and a smaller city situated in a very polluted region; in this case the Po Valley. Results from multiple CityScan instruments will be used in conjunction with data from ground based in-situ monitor networks to evaluate the ability of in-situ monitors to effectively assess the air quality in an urban environment. Trend analysis will also be shown to demonstrate any changes in the air quality in London during the time of the Olympic Games in comparison with a normal summer.

Detection of BrO plumes over various sources using OMI and GOME-2 measurements

NASA Astrophysics Data System (ADS)

Seo, Sora; Richter, Andreas; Blechschmidt, Anne-Marlene; Burrows, John P.

2017-04-01

Reactive halogen species (RHS) play important roles in the chemistry of the stratosphere and troposphere. They are responsible for ozone depletion through catalytic reaction cycles, changes in the OH/HO2 and NO/NO2 ratios, and oxidation of compounds such as gaseous elemental mercury (GEM) and dimethyl sulphide (DMS). Thus, monitoring of halogen oxides is important for understanding global atmospheric oxidation capacity and climate change. Bromine monoxide (BrO) is one of the most common active halogen oxides. In the troposphere, large amounts of bromine are detected in Polar Regions in spring, over salt lakes, and in volcanic plumes. In this study, we analyse BrO column densities using OMI and GOME-2 observations. The measured spectra from both UV-visible nadir satellites were analyzed using the differential optical absorption spectroscopy (DOAS) method with different settings depending on the instrumental characteristics. Large amounts of volcanic BrO from the Kasatochi eruption in 2008 were detected for 6 days from August 8 to August 13. Especially large BrO amounts were found in the plume center for 3 days from August 9 to 11 with slant column densities (SCD) of up to ˜1.6x1015 molecules cm-2 and ˜5.5x1014 molecules cm-2 in OMI and GOME-2 measurements, respectively. In addition to the volcanic sources, events of widespread BrO enhancements were also observed over the Arctic and Antarctic coastal regions during the spring time by both satellites. As the overpass time of the two instruments is not the same, differences between the two data sets are expected. In this study, the agreement between OMI and GOME-2 BrO data is investigated using both the operational products and different DOAS fits. Systematic differences are found in BrO slant columns and fitting residuals, both being larger in the case of OMI data. In addition, results are sensitive to the choice of fitting window. From a monitoring point of view, due to the higher spatial resolution of OMI compared to GOME-2, OMI results are better suited for observing the shape variation and transport pattern of volcanic BrO. This will be further improved with upcoming the European Sentinel 5 Precursor satellite which has an even higher spatial resolution (3.5 / 7x7 km2).

A wide field-of-view imaging DOAS instrument for two-dimensional trace gas mapping from aircraft

NASA Astrophysics Data System (ADS)

Schönhardt, A.; Altube, P.; Gerilowski, K.; Krautwurst, S.; Hartmann, J.; Meier, A. C.; Richter, A.; Burrows, J. P.

2015-12-01

The Airborne imaging differential optical absorption spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP) has been developed for the purpose of trace gas measurements and pollution mapping. The instrument has been characterized and successfully operated from aircraft. Nitrogen dioxide (NO2) columns were retrieved from the AirMAP observations. A major benefit of the push-broom imaging instrument is the spatially continuous, gap-free measurement sequence independent of flight altitude, a valuable characteristic for mapping purposes. This is made possible by the use of a charge coupled device (CCD) frame-transfer detector. A broad field of view across track of around 48° is achieved with wide-angle entrance optics. This leads to a swath width of about the same size as the flight altitude. The use of fibre coupled light intake optics with sorted light fibres allows flexible instrument positioning within the aircraft and retains the very good imaging capabilities. The measurements yield ground spatial resolutions below 100 m depending on flight altitude. The number of viewing directions is chosen from a maximum of 35 individual viewing directions (lines of sight, LOS) represented by 35 individual fibres. The selection is adapted to each situation by averaging according to signal-to-noise or spatial resolution requirements. Observations at 30 m spatial resolution are obtained when flying at 1000 m altitude and making use of all 35 viewing directions. This makes the instrument a suitable tool for mapping trace gas point sources and small-scale variability. The position and aircraft attitude are taken into account for accurate spatial mapping using the Attitude and Heading Reference System of the aircraft. A first demonstration mission using AirMAP was undertaken in June 2011. AirMAP was operated on the AWI Polar-5 aircraft in the framework of the AIRMETH-2011 campaign. During a flight above a medium-sized coal-fired power plant in north-west Germany, AirMAP clearly detected the emission plume downwind from the exhaust stack, with NO2 vertical columns around 2 × 1016 molecules cm-2 in the plume centre. NOx emissions estimated from the AirMAP observations are consistent with reports in the European Pollutant Release and Transfer Register. Strong spatial gradients and variability in NO2 amounts across and along flight direction are observed, and small-scale enhancements of NO2 above a motorway are detected.

Parameterization retrieval of trace gas volume mixing ratios from Airborne MAX-DOAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dix, Barbara; Koenig, Theodore K.; Volkamer, Rainer

We present a parameterization retrieval of volume mixing ratios (VMRs) from differential slant column density (dSCD) measurements by Airborne Multi-AXis Differential Optical Absorption Spectroscopy (AMAX-DOAS). The method makes use of the fact that horizontally recorded limb spectra (elevation angle 0°) are strongly sensitive to the atmospheric layer at instrument altitude. These limb spectra are analyzed using reference spectra that largely cancel out column contributions from above and below the instrument, so that the resulting limb dSCDs, i.e., the column integrated concentration with respect to a reference spectrum, are almost exclusively sensitive to the atmospheric layers around instrument altitude. The conversionmore » of limb dSCDs into VMRs is then realized by calculating box air mass factors (Box-AMFs) for a Rayleigh atmosphere and applying a scaling factor constrained by O 4 dSCDs to account for aerosol extinction. An iterative VMR retrieval scheme corrects for trace gas profile shape effects. Benefits of this method are (1) a fast conversion that only requires the computation of Box-AMFs in a Rayleigh atmosphere; (2) neither local aerosol extinction nor the slant column density in the DOAS reference (SCD ref) needs to be known; and (3) VMRs can be retrieved for every measurement point along a flight track, thus increasing statistics and adding flexibility to capture concentration gradients. Sensitivity studies are performed for bromine monoxide (BrO), iodine monoxide (IO) and nitrogen dioxide (NO 2), using (1) simulated dSCD data for different trace gas and aerosol profiles and (2) field measurements from the Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxygenated VOC (TORERO) field experiment. For simulated data in a Rayleigh atmosphere, the agreement between the VMR from the parameterization method (VMR para) and the true VMR (VMR true) is excellent for all trace gases. Offsets, slopes and R 2 values for the linear fit of VMR para over VMR true are, respectively (0.008 ± 0.001) pptv, 0.988 ± 0.001, 0.987 for BrO; (-0.0066 ± 0.0001) pptv, 1.0021 ± 0.0003, 0.9979 for IO; (-0.17 ± 0.03) pptv, 1.0036 ± 0.0001, 0.9997 for NO 2. The agreement for atmospheres with aerosol shows comparable R 2 values to the Rayleigh case, but slopes deviate a bit more from one: (0.093 ± 0.002) pptv, 0.933 ± 0.002, 0.907 for BrO; (0.0021 ± 0.0004) pptv, 0.887 ± 0.001, 0.973 for IO; (8.5 ± 0.1) pptv, 0.8302 ± 0.0006, 0.9923 for NO 2. VMR para from field data are further compared with optimal estimation retrievals (VMR OE). Least orthogonal distance fit of the data give the following equations: BrO para = (0.1 ± 0.2) pptv + (0.95 ± 0.14) × BrO OE; IO para = (0.01 ± 0.02) pptv + (1.00 ± 0.12) × IO OE; NO 2para = (3.9 ± 2.5) pptv + (0.87 ± 0.15) × NO 2OE. Overall, we conclude that the parameterization retrieval is accurate with an uncertainty of 20 % for IO, 30 % for BrO and NO 2, but not better than 0.05 pptv IO, 0.5 pptv BrO and 10 pptv NO 2. Finally, the retrieval is applicable over a wide range of atmospheric conditions and measurement geometries and not limited to the interpretation of vertical profile measurements in the remote troposphere.« less

Parameterization retrieval of trace gas volume mixing ratios from Airborne MAX-DOAS

DOE PAGES

Dix, Barbara; Koenig, Theodore K.; Volkamer, Rainer

2016-11-28

We present a parameterization retrieval of volume mixing ratios (VMRs) from differential slant column density (dSCD) measurements by Airborne Multi-AXis Differential Optical Absorption Spectroscopy (AMAX-DOAS). The method makes use of the fact that horizontally recorded limb spectra (elevation angle 0°) are strongly sensitive to the atmospheric layer at instrument altitude. These limb spectra are analyzed using reference spectra that largely cancel out column contributions from above and below the instrument, so that the resulting limb dSCDs, i.e., the column integrated concentration with respect to a reference spectrum, are almost exclusively sensitive to the atmospheric layers around instrument altitude. The conversionmore » of limb dSCDs into VMRs is then realized by calculating box air mass factors (Box-AMFs) for a Rayleigh atmosphere and applying a scaling factor constrained by O 4 dSCDs to account for aerosol extinction. An iterative VMR retrieval scheme corrects for trace gas profile shape effects. Benefits of this method are (1) a fast conversion that only requires the computation of Box-AMFs in a Rayleigh atmosphere; (2) neither local aerosol extinction nor the slant column density in the DOAS reference (SCD ref) needs to be known; and (3) VMRs can be retrieved for every measurement point along a flight track, thus increasing statistics and adding flexibility to capture concentration gradients. Sensitivity studies are performed for bromine monoxide (BrO), iodine monoxide (IO) and nitrogen dioxide (NO 2), using (1) simulated dSCD data for different trace gas and aerosol profiles and (2) field measurements from the Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxygenated VOC (TORERO) field experiment. For simulated data in a Rayleigh atmosphere, the agreement between the VMR from the parameterization method (VMR para) and the true VMR (VMR true) is excellent for all trace gases. Offsets, slopes and R 2 values for the linear fit of VMR para over VMR true are, respectively (0.008 ± 0.001) pptv, 0.988 ± 0.001, 0.987 for BrO; (-0.0066 ± 0.0001) pptv, 1.0021 ± 0.0003, 0.9979 for IO; (-0.17 ± 0.03) pptv, 1.0036 ± 0.0001, 0.9997 for NO 2. The agreement for atmospheres with aerosol shows comparable R 2 values to the Rayleigh case, but slopes deviate a bit more from one: (0.093 ± 0.002) pptv, 0.933 ± 0.002, 0.907 for BrO; (0.0021 ± 0.0004) pptv, 0.887 ± 0.001, 0.973 for IO; (8.5 ± 0.1) pptv, 0.8302 ± 0.0006, 0.9923 for NO 2. VMR para from field data are further compared with optimal estimation retrievals (VMR OE). Least orthogonal distance fit of the data give the following equations: BrO para = (0.1 ± 0.2) pptv + (0.95 ± 0.14) × BrO OE; IO para = (0.01 ± 0.02) pptv + (1.00 ± 0.12) × IO OE; NO 2para = (3.9 ± 2.5) pptv + (0.87 ± 0.15) × NO 2OE. Overall, we conclude that the parameterization retrieval is accurate with an uncertainty of 20 % for IO, 30 % for BrO and NO 2, but not better than 0.05 pptv IO, 0.5 pptv BrO and 10 pptv NO 2. Finally, the retrieval is applicable over a wide range of atmospheric conditions and measurement geometries and not limited to the interpretation of vertical profile measurements in the remote troposphere.« less

Intercomparison of daytime stratospheric NO2 satellite retrievals and model simulations

NASA Astrophysics Data System (ADS)

Belmonte Rivas, M.; Veefkind, P.; Boersma, F.; Levelt, P.; Eskes, H.; Gille, J.

2014-01-01

This paper evaluates the agreement between stratospheric NO2 retrievals from infrared limb sounders (MIPAS and HIRDLS) and solar UV/VIS backscatter sensors (OMI, SCIAMACHY limb and nadir) over the 2005-2007 period and across the seasons. The observational agreement is contrasted with the representation of NO2 profiles in 3-D chemical transport models such as the Whole Atmosphere Community Climate Model (SD-WACCM) and TM4. A conclusion central to this work is that the definition of a reference for stratospheric NO2 columns formed by consistent agreement among SCIAMACHY, MIPAS and HIRDLS limb records (all of which agree to within 0.25 × 1015 molecules cm-2 or better than 10%) allows us to draw attention to relative errors in other datasets, e.g.: (1) the WACCM model overestimates NO2 densities in the extratropical lower stratosphere, particularly over northern latitudes by up to 35% relative to limb observations, and (2) there are remarkable discrepancies between stratospheric NO2 column estimates from limb and nadir techniques, with a characteristic seasonal and latitude dependent pattern. We find that SCIAMACHY nadir and OMI stratospheric columns show overall biases of -0.6 × 1015 molecules cm-2 (-20%) and +0.6 × 10 15 molecules cm-2 (+20%) relative to limb observations. It is highlighted that biases in nadir stratospheric columns are not expected to affect tropospheric retrievals significantly, and that they can be attributed to errors in the total slant column density, either related to algorithmic or instrumental effects. In order to obtain accurate and long time series of stratospheric NO2, a critical evaluation of the currently used Differential Optical Absorption Spectroscopy (DOAS) approaches to nadir retrievals becomes essential, as well as their agreement to limb and ground-based observations, particularly now that limb techniques are giving way to nadir observations as the next generation of climate and air quality monitoring instruments pushes forth.