Derivative Analysis of Absorption Features in Hyperspectral Remote Sensing Data of Carbonate Sediments

DTIC Science & Technology

2002-12-30

reflectance of carbonate sediments and application to shallow water benthic habitat classification,” Doctoral Dissertation, University of Miami. Chap.3...resolve overlapping features. A primary application has been to analyze pigment and chemical composition of leaves in order to track physiological...final absorption feature was observed at 630 nm, in a region associated with the biliprotein, phycocyanin [16,17]. As biliproteins are water soluble

Classification by diagnosing all absorption features (CDAF) for the most abundant minerals in airborne hyperspectral images

NASA Astrophysics Data System (ADS)

Mobasheri, Mohammad Reza; Ghamary-Asl, Mohsen

2011-12-01

Imaging through hyperspectral technology is a powerful tool that can be used to spectrally identify and spatially map materials based on their specific absorption characteristics in electromagnetic spectrum. A robust method called Tetracorder has shown its effectiveness at material identification and mapping, using a set of algorithms within an expert system decision-making framework. In this study, using some stages of Tetracorder, a technique called classification by diagnosing all absorption features (CDAF) is introduced. This technique enables one to assign a class to the most abundant mineral in each pixel with high accuracy. The technique is based on the derivation of information from reflectance spectra of the image. This can be done through extraction of spectral absorption features of any minerals from their respected laboratory-measured reflectance spectra, and comparing it with those extracted from the pixels in the image. The CDAF technique has been executed on the AVIRIS image where the results show an overall accuracy of better than 96%.

The 4.5 micron Sulfate Absorption Feature on Mars and Its Relationship to Formation Environment

NASA Technical Reports Server (NTRS)

Blaney, D. L.

2001-01-01

The 4.5 micron sulfate absorption feature on Mars is spatially variable. It is a sensitive composition and hydration state and can be used to identify different types of aqueous environments. Additional information is contained in the original extended abstract.

IUE detector saturation and the new 2800 A absorption feature 'discovered' by Karim, Hoyle, and Wickramasinghe

NASA Astrophysics Data System (ADS)

Savage, B. D.; Sitko, M. L.

1984-03-01

The 2800 A feature of Karim et al. (1983) is shown to be the result of IUE detector saturation effects in overexposed spectra. A properly exposed spectrum and an overexposed one are shown. The latter shows a broad absorption peak at 2800 A while the former does not.

4.6 micron absorption features due to solid phase CO and cyano group molecules toward compact infrared sources

NASA Technical Reports Server (NTRS)

Lacy, J. H.; Baas, F.; Allamandola, L. J.; Van De Bult, C. E. P.; Persson, S. E.; Mcgregor, P. J.; Lonsdale, C. J.; Geballe, T. R.

1984-01-01

Spectra obtained at a resolving power of 840, for seven protostellar sources in the region of the 4.67-micron fundamental vibrational band of CO, indicate that the deep absorption feature in W33A near 4.61 microns consists of three features which are seen in other sources, but with varying relative strength. UV-irradiation laboratory experiments with 'dirty ice' temperature cycling allow the identification of two of the features cited with solid CO and CO complexed to other molecules. Cyano group-containing molecules have a lower vapor pressure than CO, and can therefore survive in much warmer environments. The formation and location of the CO- and CN-bearing grain mantles and sources of UV irradiation in cold molecular clouds are discussed. Plausible UV light sources can produce the observed cyano group features, but only under conditions in which local heat sources do not cause evaporation of the CO molecules prior to their photoprocessing.

Special Features of Light Absorption by the Dimer of Bilayer Microparticles

NASA Astrophysics Data System (ADS)

Geints, Yu. É.; Panina, E. K.; Zemlyanov, A. A.

2018-05-01

Results of numerical simulation of light absorption by the dimer of bilayer spherical particles consisting of a water core and a polymer shell absorbing radiation are presented. The spatial distribution and the amplitude characteristics of the volume density of the absorbed power are investigated. It is shown that for a certain spatial dimer configuration, the maximal achievable density of the absorbed power is realized. It is also established that for closely spaced microcapsules with high shell absorption indices, the total power absorbed in the dimer volume can increase in comparison with the radiation absorption by two insulated microparticles.

Interstellar proteins and the discovery of a new absorption feature at lambda = 2800 A

NASA Astrophysics Data System (ADS)

Karim, L. M.; Hoyle, F.; Wickramasinghe, N. C.

1983-07-01

In order to check the presence of biogenic materials in interstellar grains, the spectra of three early-type, heavily reddened stars recorded by the IUE were examined. These stars showed comparatively weak absorption at 2200 A, minimizing the effect of graphite grains. A broad absorption feature centered on 2800 A is discovered in HD 14250 and interpreted to be due to the amino acid tryptophan. Comparison of the spectrum with that of the calculated extinction behavior of graphite spheres of radii 0.02 microns suggests that the latter are not responsible for the observed spectrum.

Relationships between vegetation indices, radiation absorption, and net photosynthesis evaluated by a sensitivity analysis

NASA Technical Reports Server (NTRS)

Choudhury, Bhaskar J.

1987-01-01

A two-stream approximation to the radiative-transfer equation is used to calculate the vegetation indices (simple ratio and normalized difference), the fraction of incident photosynthetically active radiation (PAR) absorbed by the canopy, and the daily mean canopy net photosynthesis under clear-sky conditions. The model calculations are tested against field observations over wheat, cotton, corn, and soybean. The relationships between the vegetation indices and radiation absorption or net photosynthesis are generally found to be curvilinear, and changes in the soil reflectance affected these relationships. The curvilinearity of the relationship between normalized differences and PAR absorption decreases as the magnitude of soil reflectance increases. The vegetation indices might provide the fractional radiation absorption with some a priori knowledge about soil reflectance. The relationship between the vegetation indices and net photosynthesis must be distinguished for C3 and C4 crops. Effects of spatial heterogeneity are discussed.

Radial measurements of IMF-sensitive absorption features in two massive ETGs

NASA Astrophysics Data System (ADS)

Vaughan, Sam P.; Davies, Roger L.; Zieleniewski, Simon; Houghton, Ryan C. W.

2018-03-01

We make radial measurements of stellar initial mass function (IMF) sensitive absorption features in the two massive early-type galaxies NGC 1277 and IC 843. Using the Oxford Short Wavelength Integral Field specTrogaph (SWIFT), we obtain resolved measurements of the Na I 0.82 and FeH 0.99 indices, amongst others, finding both galaxies show strong gradients in Na I absorption combined with flat FeH profiles at ˜0.4 Å. We find these measurements may be explained by radial gradients in the IMF, appropriate abundance gradients in [Na/Fe] and [Fe/H], or a combination of the two, and our data are unable to break this degeneracy. We also use full spectral fitting to infer global properties from an integrated spectrum of each object, deriving a unimodal IMF slope consistent with Salpeter in IC 843 (x = 2.27 ± 0.17) but steeper than Salpeter in NGC 1277 (x = 2.69 ± 0.11), despite their similar FeH equivalent widths. Independently, we fit the strength of the FeH feature and compare to the E-MILES and CvD12 stellar population libraries, finding agreement between the models. The IMF values derived in this way are in close agreement with those from spectral fitting in NGC 1277 (x_{CvD}=2.59^{+0.25}_{-0.48}, x_{E-MILES}=2.77± 0.31), but are less consistent in IC 843, with the IMF derived from FeH alone leading to steeper slopes than when fitting the full spectrum (x_{CvD}=2.57^{+0.30}_{-0.41}, x_{E-MILES}=2.72± 0.25). This work highlights the importance of a large wavelength coverage for breaking the degeneracy between abundance and IMF variations, and may bring into doubt the use of the Wing-Ford band as an IMF index if used without other spectral information.

The origin of absorptive features in the two-dimensional electronic spectra of rhodopsin.

PubMed

Farag, Marwa H; Jansen, Thomas L C; Knoester, Jasper

2018-05-09

In rhodopsin, the absorption of a photon causes the isomerization of the 11-cis isomer of the retinal chromophore to its all-trans isomer. This isomerization is known to occur through a conical intersection (CI) and the internal conversion through the CI is known to be vibrationally coherent. Recently measured two-dimensional electronic spectra (2DES) showed dramatic absorptive spectral features at early waiting times associated with the transition through the CI. The common two-state two-mode model Hamiltonian was unable to elucidate the origin of these features. To rationalize the source of these features, we employ a three-state three-mode model Hamiltonian where the hydrogen out-of plane (HOOP) mode and a higher-lying electronic state are included. The 2DES of the retinal chromophore in rhodopsin are calculated and compared with the experiment. Our analysis shows that the source of the observed features in the measured 2DES is the excited state absorption to a higher-lying electronic state and not the HOOP mode.

Understanding the features in the ultrafast transient absorption spectra of CdSe quantum dots

NASA Astrophysics Data System (ADS)

Zhang, Cheng; Do, Thanh Nhut; Ong, Xuanwei; Chan, Yinthai; Tan, Howe-Siang

2016-12-01

We describe a model to explain the features of the ultrafast transient absorption (TA) spectra of CdSe core type quantum dots (QDs). The measured TA spectrum consists of contributions by the ground state bleach (GSB), stimulated emission (SE) and excited state absorption (ESA) processes associated with the three lowest energy transition of the QDs. We model the shapes of the GSB, SE and ESA spectral components after fits to the linear absorption. The spectral positions of the ESA components take into account the biexcitonic binding energy. In order to obtain the correct weightage of the GSB, SE and ESA components to the TA spectrum, we enumerate the set of coherence transfer pathways associated with these processes. From our fits of the experimental TA spectra of 65 Å diameter QDs, biexcitonic binding energies for the three lowest energy transitions are obtained.

Investigations on the 1.7 micron residual absorption feature in the vegetation reflection spectrum

NASA Technical Reports Server (NTRS)

Verdebout, J.; Jacquemoud, S.; Andreoli, G.; Hosgood, B.; Sieber, A.

1993-01-01

The detection and interpretation of the weak absorption features associated with the biochemical components of vegetation is of great potential interest to a variety of applications ranging from classification to global change studies. This recent subject is also challenging because the spectral signature of the biochemicals is only detectable as a small distortion of the infrared spectrum which is mainly governed by water. Furthermore, the interpretation is complicated by complexity of the molecules (lignin, cellulose, starch, proteins) which contain a large number of different and common chemical bonds. In this paper, we present investigations on the absorption feature centered at 1.7 micron; these were conducted both on AVIRIS data and laboratory reflectance spectra of leaves.

The application of feature selection to the development of Gaussian process models for percutaneous absorption.

PubMed

Lam, Lun Tak; Sun, Yi; Davey, Neil; Adams, Rod; Prapopoulou, Maria; Brown, Marc B; Moss, Gary P

2010-06-01

The aim was to employ Gaussian processes to assess mathematically the nature of a skin permeability dataset and to employ these methods, particularly feature selection, to determine the key physicochemical descriptors which exert the most significant influence on percutaneous absorption, and to compare such models with established existing models. Gaussian processes, including automatic relevance detection (GPRARD) methods, were employed to develop models of percutaneous absorption that identified key physicochemical descriptors of percutaneous absorption. Using MatLab software, the statistical performance of these models was compared with single linear networks (SLN) and quantitative structure-permeability relationships (QSPRs). Feature selection methods were used to examine in more detail the physicochemical parameters used in this study. A range of statistical measures to determine model quality were used. The inherently nonlinear nature of the skin data set was confirmed. The Gaussian process regression (GPR) methods yielded predictive models that offered statistically significant improvements over SLN and QSPR models with regard to predictivity (where the rank order was: GPR > SLN > QSPR). Feature selection analysis determined that the best GPR models were those that contained log P, melting point and the number of hydrogen bond donor groups as significant descriptors. Further statistical analysis also found that great synergy existed between certain parameters. It suggested that a number of the descriptors employed were effectively interchangeable, thus questioning the use of models where discrete variables are output, usually in the form of an equation. The use of a nonlinear GPR method produced models with significantly improved predictivity, compared with SLN or QSPR models. Feature selection methods were able to provide important mechanistic information. However, it was also shown that significant synergy existed between certain parameters, and as such it

Airborne spectroradiometry: The application of AIS data to detecting subtle mineral absorption features

NASA Technical Reports Server (NTRS)

Cocks, T. D.; Green, A. A.

1986-01-01

Analysis of Airborne Imaging Spectrometer (AIS) data acquired in Australia has revealed a number of operational problems. Horizontal striping in AIS imagery and spectral distortions due to order overlap were investigated. Horizontal striping, caused by grating position errors can be removed with little or no effect on spectral details. Order overlap remains a problem that seriously compromises identification of subtle mineral absorption features within AIS spectra. A spectrometric model of the AIS was developed to assist in identifying spurious spectral features, and will be used in efforts to restore the spectral integrity of the data.

Designing basin-customized combined drought indices via feature extraction

NASA Astrophysics Data System (ADS)

Zaniolo, Marta; Giuliani, Matteo; Castelletti, Andrea

2017-04-01

The socio-economic costs of drought are progressively increasing worldwide due to the undergoing alteration of hydro-meteorological regimes induced by climate change. Although drought management is largely studied in the literature, most of the traditional drought indexes fail in detecting critical events in highly regulated systems, which generally rely on ad-hoc formulations and cannot be generalized to different context. In this study, we contribute a novel framework for the design of a basin-customized drought index. This index represents a surrogate of the state of the basin and is computed by combining the available information about the water available in the system to reproduce a representative target variable for the drought condition of the basin (e.g., water deficit). To select the relevant variables and how to combine them, we use an advanced feature extraction algorithm called Wrapper for Quasi Equally Informative Subset Selection (W-QEISS). The W-QEISS algorithm relies on a multi-objective evolutionary algorithm to find Pareto-efficient subsets of variables by maximizing the wrapper accuracy, minimizing the number of selected variables (cardinality) and optimizing relevance and redundancy of the subset. The accuracy objective is evaluated trough the calibration of a pre-defined model (i.e., an extreme learning machine) of the water deficit for each candidate subset of variables, with the index selected from the resulting solutions identifying a suitable compromise between accuracy, cardinality, relevance, and redundancy. The proposed methodology is tested in the case study of Lake Como in northern Italy, a regulated lake mainly operated for irrigation supply to four downstream agricultural districts. In the absence of an institutional drought monitoring system, we constructed the combined index using all the hydrological variables from the existing monitoring system as well as the most common drought indicators at multiple time aggregations. The soil

Iron K Features in the Quasar E 1821+643: Evidence for Gravitationally Redshifted Absorption?

NASA Technical Reports Server (NTRS)

Yaqoob, Tahir; Serlemitsos, Peter

2005-01-01

We report a Chandra high-energy grating detection of a narrow, redshifted absorption line superimposed on the red wing of a broad Fe K line in the z = 0.297 quasar E 1821+643. The absorption line is detected at a confidence level, estimated by two different methods, in the range approx. 2 - 3 sigma. Although the detection significance is not high enough to exclude a non-astrophysical origin, accounting for the absorption feature when modeling the X-ray spectrum implies that the Fe-K emission line is broad, and consistent with an origin in a relativistic accretion disk. Ignoring the apparent absorption feature leads to the conclusion that the Fe-K emission line is narrower, and also affects the inferred peak energy of the line (and hence the inferred ionization state of Fe). If the absorption line (at approx. 6.2 keV in the quasar frame) is real, we argue that it could be due to gravitationally redshifted Fe XXV or Fe XXVI resonance absorption within approx. 10 - 20 gravitational radii of the putative central black hole. The absorption line is not detected in earlier ASCA and Chandra low-energy grating observations, but the absorption line is not unequivocally ruled out by these data. The Chandra high-energy grating Fe-K emission line is consistent with an origin predominantly in Fe I-XVII or so. In an ASCA observation eight years earlier, the Fe-K line peaked at approx. 6.6 keV, closer to the energies of He-like Fe triplet lines. Further, in a Chandra low-energy grating observation the Fe-K line profile was double-peaked, one peak corresponding to Fe I-XVII or so, the other peak to Fe XXVI Ly alpha. Such a wide range in ionization state of Fe is not ruled out by the HEG and ASCA data either, and is suggestive of a complex structure for the line-emitter.

Differential absorption lidar observation on small-time-scale features of water vapor in the atmospheric boundary layer

NASA Astrophysics Data System (ADS)

Kong, Wei; Li, Jiatang; Liu, Hao; Chen, Tao; Hong, Guanglie; Shu, Rong

2017-11-01

Observation on small-time-scale features of water vapor density is essential for turbulence, convection and many other fast atmospheric processes study. For the high signal-to-noise signal of elastic signal acquired by differential absorption lidar, it has great potential for all-day water vapor turbulence observation. This paper presents a set of differential absorption lidar at 935nm developed by Shanghai Institute of Technical Physics of the Chinese Academy of Science for water vapor turbulence observation. A case at the midday is presented to demonstrate the daytime observation ability of this system. "Autocovariance method" is used to separate the contribution of water vapor fluctuation from random error. The results show that the relative error is less than 10% at temporal and spatial resolution of 10 seconds and 60 meters in the ABL. This indicate that the system has excellent performance for daytime water vapor turbulence observation.

Randic and Schultz molecular topological indices and their correlation with some X-ray absorption parameters

NASA Astrophysics Data System (ADS)

Khatri, Sunil; Kekre, Pravin A.; Mishra, Ashutosh

2016-10-01

The properties of a molecular system are affected by the topology of molecule. Therefore many studies have been made where the various physic-chemical properties are correlated with the topological indices. These studies have shown a very good correlation demonstrating the utility of the graph theoretical approach. It is, therefore, very natural to expect that the various physical properties obtained by the X-ray absorption spectra may also show correlation with the topological indices. Some complexes were used to establish correlation between topological indices and some X-ray absorption parameters like chemical shift. The chemical shift is on the higher energy side of the metal edge in these complexes. The result obtained in these studies shows that the topological indices of organic molecule acting as a legands can be used for estimating edge shift theoretically.

Optical constants of ammonium sulfate in the infrared. [stratospheric aerosol refractive and absorption indices

NASA Technical Reports Server (NTRS)

Downing, H. D.; Pinkley, L. W.; Sethna, P. P.; Williams, D.

1977-01-01

The infrared spectral reflectance at near normal incidence has been measured for 3.2 M, 2.4 M, and 1.6 M solutions of ammonium sulfate, an aerosol abundant in the stratosphere and also present in the troposphere. Kramers-Kronig analysis was used to determine values of the refractive and absorption indices from the measured spectral reflectance. A synthetic spectrum of crystalline ammonium sulfate was obtained by extrapolation of the absorption index obtained for the solution to the absorber number densities of the NH4 and SO4 ions characteristic of the crystal.

Absorption line indices in the UV. I. Empirical and theoretical stellar population models

NASA Astrophysics Data System (ADS)

Maraston, C.; Nieves Colmenárez, L.; Bender, R.; Thomas, D.

2009-01-01

Aims: Stellar absorption lines in the optical (e.g. the Lick system) have been extensively studied and constitute an important stellar population diagnostic for galaxies in the local universe and up to moderate redshifts. Proceeding towards higher look-back times, galaxies are younger and the ultraviolet becomes the relevant spectral region where the dominant stellar populations shine. A comprehensive study of ultraviolet absorption lines of stellar population models is however still lacking. With this in mind, we study absorption line indices in the far and mid-ultraviolet in order to determine age and metallicity indicators for UV-bright stellar populations in the local universe as well as at high redshift. Methods: We explore empirical and theoretical spectral libraries and use evolutionary population synthesis to compute synthetic line indices of stellar population models. From the empirical side, we exploit the IUE-low resolution library of stellar spectra and system of absorption lines, from which we derive analytical functions (fitting functions) describing the strength of stellar line indices as a function of gravity, temperature and metallicity. The fitting functions are entered into an evolutionary population synthesis code in order to compute the integrated line indices of stellar populations models. The same line indices are also directly evaluated on theoretical spectral energy distributions of stellar population models based on Kurucz high-resolution synthetic spectra, In order to select indices that can be used as age and/or metallicity indicators for distant galaxies and globular clusters, we compare the models to data of template globular clusters from the Magellanic Clouds with independently known ages and metallicities. Results: We provide synthetic line indices in the wavelength range ~1200 Å to ~3000 Å for stellar populations of various ages and metallicities.This adds several new indices to the already well-studied CIV and SiIV absorptions

Mg I absorption features in the solar spectrum near 9 and 12 microns

NASA Technical Reports Server (NTRS)

Glenar, David A.; Reuter, Dennis C.; Deming, Drake; Chang, Edward S.

1988-01-01

High-resolution FTS observations from the Kitt Peak National Solar Observatory and the Spacelab 3 ATMOS experiment have revealed additional infrared transitions due to Mg I in the spectra of both quiet sun and sunspot penumbra. In contrast to previous observations, these transitions are seen in absorption, not emission. Absorption intensities range from 1 to 7 percent of the continuum in the quiet sun. In the penumbra, the same features appear to show Zeeman splitting. Modeling of the line profiles in the photospheric spectrum shows evidence for a factor of three overabundance in the n = 5 or more levels of Mg I in the upper photosphere, but with no deviations from a Planck source function. It is concluded that whatever the process that produces the emission (including the Lemke and Holweger mechanism), it must occur well above the tau(5000) = 0.01 level.

Exploring multivariate representations of indices along linear geographic features

NASA Astrophysics Data System (ADS)

Bleisch, Susanne; Hollenstein, Daria

2018-05-01

A study of the walkability of a Swiss town required finding suitable representations of multivariate geographical da-ta. The goal was to represent multiple indices of walkability concurrently and visualizing the data along the street network it relates to. Different indices of pedestrian friendliness were assessed for short street sections and then mapped to an overlaid grid. Basic and composite glyphs were designed using square- or triangle-areas to display one to four index values concurrently within the grid structure. Color was used to indicate different indices. Implement-ing visualizations for different combinations of index sets, we find that single values can be emphasized or de-emphasized by selecting the color scheme accordingly and that different color selections either allow perceiving sin-gle values or overall trends over the evaluated area. Values for up to four indices can be displayed in combination within the resulting geovisualizations and the underlying gridded road network references the data to its real world locations.

Ultrafast transient absorption revisited: Phase-flips, spectral fingers, and other dynamical features

SciTech Connect

Cina, Jeffrey A., E-mail: cina@uoregon.edu; Kovac, Philip A.; Jumper, Chanelle C.

We rebuild the theory of ultrafast transient-absorption/transmission spectroscopy starting from the optical response of an individual molecule to incident femtosecond pump and probe pulses. The resulting description makes use of pulse propagators and free molecular evolution operators to arrive at compact expressions for the several contributions to a transient-absorption signal. In this alternative description, which is physically equivalent to the conventional response-function formalism, these signal contributions are conveniently expressed as quantum mechanical overlaps between nuclear wave packets that have undergone different sequences of pulse-driven optical transitions and time-evolution on different electronic potential-energy surfaces. Using this setup in application to amore » simple, multimode model of the light-harvesting chromophores of PC577, we develop wave-packet pictures of certain generic features of ultrafast transient-absorption signals related to the probed-frequency dependence of vibrational quantum beats. These include a Stokes-shifting node at the time-evolving peak emission frequency, antiphasing between vibrational oscillations on opposite sides (i.e., to the red or blue) of this node, and spectral fingering due to vibrational overtones and combinations. Our calculations make a vibrationally abrupt approximation for the incident pump and probe pulses, but properly account for temporal pulse overlap and signal turn-on, rather than neglecting pulse overlap or assuming delta-function excitations, as are sometimes done.« less

Salient features of dependence in daily US stock market indices

NASA Astrophysics Data System (ADS)

Gil-Alana, Luis A.; Cunado, Juncal; de Gracia, Fernando Perez

2013-08-01

This paper deals with the analysis of long range dependence in the US stock market. We focus first on the log-values of the Dow Jones Industrial Average, Standard and Poors 500 and Nasdaq indices, daily from February, 1971 to February, 2007. The volatility processes are examined based on the squared and the absolute values of the returns series, and the stability of the parameters across time is also investigated in both the level and the volatility processes. A method that permits us to estimate fractional differencing parameters in the context of structural breaks is conducted in this paper. Finally, the “day of the week” effect is examined by looking at the order of integration for each day of the week, providing also a new modeling approach to describe the dependence in this context.

Ultraviolet spectra of quenched carbonaceous composite derivatives: Comparison to the '217 nanometer' interstellar absorption feature

NASA Technical Reports Server (NTRS)

Sakata, Akira; Wada, Setsuko; Tokunaga, Alan T.; Narisawa, Takatoshi; Nakagawa, Hidehiro; Ono, Hiroshi

1994-01-01

QCCs (quenched carbonaceous composite) are amorphus carbonaceous material formed from a hydrocarbon plasma. We present the UV-visible spectra of 'filmy QCC; (obtained outside of the beam ejected from the hydrocarbon plasma) and 'dark QCC' (obtained very near to the beam) for comparison to the stellar extinction curve. When filmy QCC is heated to 500-700 C (thermally altered), the wavelength of the absorption maximum increases form 204 nm to 220-222 nm. The dark QCC has an absorption maximum at 217-222 nm. In addition, the thermally altered filmy QCC has a slope change at about 500 nm which resmbles that in the interstellar extinction curve. The resemblance of the extinction curve of the QCCs to that of the interstellar medium suggests that QCC derivatives may be representative of the type of interstellar material that produces the 217 nm interstellar medium feature. The peak extinction of the dark QCC is higher than the average interstellar extinction curve while that of the thermally altered filmy QCC is lower, so that a mixture of dark and thermally altered filmy QCC can match the peak extinction observed in the interstellar medium. It is shown from electron micrographs that most of the thermally altered flimy QCC is in the form of small grainy structure less than 4 nm in diameter. This shows that the structure unit causing the 217-222 nm feature in QCC is very small.

The Associated Absorption Features in Quasar Spectra of the Sloan Digital Sky Survey. I. Mg II Absorption Doublets

NASA Astrophysics Data System (ADS)

Chen, Zhi-Fu; Huang, Wei-Rong; Pang, Ting-Ting; Huang, Hong-Yan; Pan, Da-Sheng; Yao, Min; Nong, Wei-Jing; Lu, Mei-Mei

2018-03-01

Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for Mg II λλ2796, 2803 narrow absorption doublets in the spectra data around Mg II λ2798 emission lines. We obtain 17,316 Mg II doublets, within the redshift range of 0.3299 ≤ z abs ≤ 2.5663. We find that a velocity offset of υ r < 6000 km s‑1 is a safe boundary to constrain the vast majority of associated Mg II systems, although we find some doublets at υ r > 6000 km s‑1. If associated Mg II absorbers are defined by υ r < 6000 km s‑1, ∼33.3% of the absorbers are supposed to be contaminants of intervening systems. Removing the 33.3% contaminants, ∼4.5% of the quasars present at least one associated Mg II system with {W}{{r}}λ 2796≥slant 0.2 \\mathringA . The fraction of associated Mg II systems with high-velocity outflows correlates with the average luminosities of their central quasars, indicating a relationship between outflows and the quasar feedback power. The υ r distribution of the outflow Mg II absorbers is peaked at 1023 km s‑1, which is smaller than the corresponding value of the outflow C IV absorbers. The redshift number density evolution of absorbers (dn/dz) limited by υ r > ‑3000 km s‑1 differs from that of absorbers constrained by υ r > 2000 km s‑1. Absorbers limited by υ r > 2000 km s‑1 and higher values exhibit profiles similar to dn/dz. In addition, the dn/dz is smaller when absorbers are constrained with larger υ r . The distributions of equivalent widths, and the ratio of {W}rλ 2796/{W}rλ 2803, are the same for associated and intervening systems, and independent of quasar luminosity.

UV absorption investigation of ferromagnetically filled ultra-thick carbon onions, carriers of the 217.5 nm Interstellar Absorption Feature

NASA Astrophysics Data System (ADS)

Boi, Filippo S.; Zhang, Xiaotian; Ivaturi, Sameera; Liu, Qianyang; Wen, Jiqiu; Wang, Shanling

2017-12-01

Carbon nano-onions (CNOs) are fullerene-like structures which consist of quasi-spherical closed carbon shells. These structures have become a subject of great interest thanks to their characteristic absorption feature of interstellar origin (at 217.5 nm, 4.6 μm-1). An additional extinction peak at 3.8 μm-1 has also been reported and attributed to absorption by graphitic residues between the as-grown CNOs. Here, we report the ultraviolet absorption properties of ultra-thick CNOs filled with FePt3 crystals, which also exhibit two main absorption peaks—features located at 4.58 μm-1 and 3.44 μm-1. The presence of this additional feature is surprising and is attributed to nonmagnetic graphite flakes produced as a by-product in the pyrolysis experiment (as confirmed by magnetic separation methods). Instead, the feature at 4.58 μm-1 is associated with the π-plasmonic resonance of the CNOs structures. The FePt3 filled CNOs were fabricated in situ by an advanced one-step fast process consisting in the direct sublimation and pyrolysis of two molecular precursors, namely, ferrocene and dichloro-cyclooctadiene-platinum in a chemical vapour deposition system. The morphological, structural, and magnetic properties of the as-grown filled CNOs were characterized by a means of scanning and transmission electron microscopy, X-ray diffraction, and magnetometry.

Effect of cell-size on the energy absorption features of closed-cell aluminium foams

NASA Astrophysics Data System (ADS)

Nammi, S. K.; Edwards, G.; Shirvani, H.

2016-11-01

The effect of cell-size on the compressive response and energy absorption features of closed-cell aluminium (Al) foam were investigated by finite element method. Micromechanical models were constructed with a repeating unit-cell (RUC) which was sectioned from tetrakaidecahedra structure. Using this RUC, three Al foam models with different cell-sizes (large, medium and small) and all of same density, were built. These three different cell-size pieces of foam occupy the same volume and their domains contained 8, 27 and 64 RUCs respectively. However, the smaller cell-size foam has larger surface area to volume ratio compared to other two. Mechanical behaviour was modelled under uniaxial loading. All three aggregates (3D arrays of RUCs) of different cell-sizes showed an elastic region at the initial stage, then followed by a plateau, and finally, a densification region. The smaller cell size foam exhibited a higher peak-stress and a greater densification strain comparing other two cell-sizes investigated. It was demonstrated that energy absorption capabilities of smaller cell-size foams was higher compared to the larger cell-sizes examined.

Detection of a deep 3-microm absorption feature in the spectrum of Amalthea (JV).

PubMed

Takato, Naruhisa; Bus, Schelte J; Terada, Hiroshi; Pyo, Tae-Soo; Kobayashi, Naoto

2004-12-24

Near-infrared spectra of Jupiter's small inner satellites Amalthea and Thebe are similar to those of D-type asteroids in the 0.8- to 2.5-micrometer wavelength range. A deep absorption feature is detected at 3 micrometers in the spectra of the trailing side of Amalthea, which is similar to that of the non-ice components of Callisto and can be attributed to hydrous minerals. These surface materials cannot be explained if the satellite formed at its present orbit by accreting from a circumjovian nebula. Amalthea and Thebe may be the remnants of Jupiter's inflowing building blocks that formed in the outer part or outside of the circumjovian nebula.

Seagrass epiphytic assemblages are strong indicators of agricultural discharge but weak indicators of host features

NASA Astrophysics Data System (ADS)

Prado, Patricia

2018-05-01

Wastewater pulses from rice agriculture are persistently discharged into the northern shore of the Alfacs Bay (Ebro Delta, NW Mediterranean) from April to November. The bay also receives water from coastal lagoons which are subjected to freshwater inputs from the Ebro River mixed to an unknown extent with agricultural wastewater during the same period. This paper compares epiphyte assemblages growing on leaves of Cymodocea nodosa in sites exposed to agricultural drainage channels, lagoon connection channels, and control sites in the Ebro Delta Natural Park (southern shore of the bay). Leaf epiphytic assemblages of Zostera noltii patches in the northern shore of the bay were also compared with those of adjacent beds of C. nodosa. Drainage channel sites had consistently distinctive assemblages (higher species richness, biomass load, and taxa composition) than control sites. Assemblages from lagoon channel sites were more variable, with three sites showing particularly high covers of epiphytic algae and two sites more similar to controls. Epiphyte patterns clearly matched in situ measures of nutrient availability, and were consistent with decreased shoot densities in discharge sites. In contrast, differences in epiphyte assemblages between seagrass species were minor, and mostly a result of higher epiphytic loads on C. nodosa than on Z. noltii, which features thinner leaves. Further research is needed to investigate the consequences of these plant and epiphyte alterations in important ecosystem processes such as decomposition and export rates, as well as overall effects of nutrients and salinity in secondary producers such as associated macroinvertebrate assemblages supporting locally important marine fisheries.

Spectroscopic determination of leaf biochemistry using band-depth analysis of absorption features and stepwise multiple linear regression

USGS Publications Warehouse

Kokaly, R.F.; Clark, R.N.

1999-01-01

We develop a new method for estimating the biochemistry of plant material using spectroscopy. Normalized band depths calculated from the continuum-removed reflectance spectra of dried and ground leaves were used to estimate their concentrations of nitrogen, lignin, and cellulose. Stepwise multiple linear regression was used to select wavelengths in the broad absorption features centered at 1.73 ??m, 2.10 ??m, and 2.30 ??m that were highly correlated with the chemistry of samples from eastern U.S. forests. Band depths of absorption features at these wavelengths were found to also be highly correlated with the chemistry of four other sites. A subset of data from the eastern U.S. forest sites was used to derive linear equations that were applied to the remaining data to successfully estimate their nitrogen, lignin, and cellulose concentrations. Correlations were highest for nitrogen (R2 from 0.75 to 0.94). The consistent results indicate the possibility of establishing a single equation capable of estimating the chemical concentrations in a wide variety of species from the reflectance spectra of dried leaves. The extension of this method to remote sensing was investigated. The effects of leaf water content, sensor signal-to-noise and bandpass, atmospheric effects, and background soil exposure were examined. Leaf water was found to be the greatest challenge to extending this empirical method to the analysis of fresh whole leaves and complete vegetation canopies. The influence of leaf water on reflectance spectra must be removed to within 10%. Other effects were reduced by continuum removal and normalization of band depths. If the effects of leaf water can be compensated for, it might be possible to extend this method to remote sensing data acquired by imaging spectrometers to give estimates of nitrogen, lignin, and cellulose concentrations over large areas for use in ecosystem studies.We develop a new method for estimating the biochemistry of plant material using

The origin of blueshifted absorption features in the X-ray spectrum of PG 1211+143: outflow or disc

NASA Astrophysics Data System (ADS)

Gallo, L. C.; Fabian, A. C.

2013-07-01

In some radio-quiet active galactic nuclei (AGN), high-energy absorption features in the X-ray spectra have been interpreted as ultrafast outflows (UFOs) - highly ionized material (e.g. Fe XXV and Fe XXVI) ejected at mildly relativistic velocities. In some cases, these outflows can carry energy in excess of the binding energy of the host galaxy. Needless to say, these features demand our attention as they are strong signatures of AGN feedback and will influence galaxy evolution. For the same reason, alternative models need to be discussed and refuted or confirmed. Gallo and Fabian proposed that some of these features could arise from resonance absorption of the reflected spectrum in a layer of ionized material located above and corotating with the accretion disc. Therefore, the absorbing medium would be subjected to similar blurring effects as seen in the disc. A priori, the existence of such plasma above the disc is as plausible as a fast wind. In this work, we highlight the ambiguity by demonstrating that the absorption model can describe the ˜7.6 keV absorption feature (and possibly other features) in the quasar PG 1211+143, an AGN that is often described as a classic example of a UFO. In this model, the 2-10 keV spectrum would be largely reflection dominated (as opposed to power law dominated in the wind models) and the resonance absorption would be originating in a layer between about 6 and 60 gravitational radii. The studies of such features constitute a cornerstone for future X-ray observatories like Astro-H and Athena+. Should our model prove correct, or at least important in some cases, then absorption will provide another diagnostic tool with which to probe the inner accretion flow with future missions.

Significance of ambient conditions in uranium absorption and emission features of laser ablation plasmas

SciTech Connect

Skrodzki, P. J.; Shah, N. P.; Taylor, N.

2016-11-01

This study employs laser ablation (LA) to investigate mechanisms for U optical signal variation under various environmental conditions during laser absorption spectroscopy (LAS) and optical emission spectroscopy (OES). Potential explored mechanisms for signal quenching related to ambient conditions include plasma chemistry (e.g., uranium oxide formation), ambient gas confinement effects, and other collisional interactions between plasma constituents and the ambient gas. LA-LAS studies show that the persistence of the U ground state population is significantly reduced in the presence of air ambient compared to nitrogen. LA-OES results yield congested spectra from which the U I 356.18 nm transition is prominent andmore » serves as the basis for signal tracking. LA-OES signal and persistence vary negligibly between the test gases (air and N2), unlike the LA-LAS results. The plume hydrodynamic features and plume fundamental properties showed similar results in both air and nitrogen ambient. Investigation of U oxide formation in the laser-produced plasma suggests that low U concentration in a sample hinders consistent detection of UO molecular spectra.« less

Significance of ambient conditions in uranium absorption and emission features of laser ablation plasmas

SciTech Connect

Skrodzki, P. J.; Shah, N. P.; Taylor, N.

2016-10-02

This study employs laser ablation (LA) to investigate mechanisms for U optical signal variation under various environmental conditions during laser absorption spectroscopy (LAS) and optical emission spectroscopy (OES). Potential mechanisms explored for signal quenching related to ambient conditions include plasma chemistry (e.g., uranium oxide formation), ambient gas confinement effects, and other collisional interactions between plas-ma constituents and the ambient gas. LA-LAS studies show that the persistence of the U ground state population is significantly reduced in the presence of air ambient compared to nitrogen. LA-OES yields congested spectra from which the U I 356.18 nm transition is prominent and servesmore » as the basis for signal tracking. LA-OES signal and per-sistence vary negligibly between the test gases (air and N 2), unlike the LA-LAS results. The plume hydrodynamic features and plume fundamental properties showed similar results in both air and nitrogen ambient. In conclusion, investigation of U oxide formation in the laser-produced plasma suggests that low U concentration in a sample hinders consistent detection of UO molecular spectra.« less

THE USE OF Y$sup 91$ AS AN INERT INDICATOR IN INTESTINAL ABSORPTION TESTS

SciTech Connect

Maisterrena, J.A.; Murphy, C.A.; Tovar, E.

The use of Y/sup 91/ as an inert-indicator in the studies of the intestinal absorption of I/sup 131/-labeled substances is reported, emphasis being given to its clinical advantages. The Y/sup 91/ is not absorbed in the gastrointestinal tract, since recovery in the feces in 22 cases was 96 plus or minus 6.7% (S.D.) of the amount given. The Y/sup 91/ and the I/sup 131/-labeled substances are homogeneously distributed throughout any given stool sample but their rate of excretion is not always parallel. A close correlation was found between the amount of I/sup 131/ excreted as obtained from the complete fecalmore » collection method and that of Y/sup 91/-indicator method in a group of 20 subjects under special supervision. The value of the Y/sup 91/ inert-indicator method where the completeness of the stool collection is doubtful is shown in 23 cases. (auth)« less

Structural, thermal and optical absorption features of heavy metal oxides doped tellurite rich glasses

NASA Astrophysics Data System (ADS)

Kaky, Kawa M.; Lakshminarayana, G.; Baki, S. O.; Kityk, I. V.; Taufiq-Yap, Y. H.; Mahdi, M. A.

In order to improve tellurite glass stability to be applicable for optical fiber amplifier applications, glasses with the composition of (70 - x)TeO2. (10)ZnO. (10)WO3. (5)Na2O. (5)TiO2. (x)Bi2O3 (x = 1, 2, 3, 4, and 5 mol%) have been produced and characterized using the related methods. Structural properties were investigated using X-ray diffraction (XRD) which confirms the non-crystalline structure and scanning electron microscopy (SEM) micrographs also confirm the XRD results. The energy dispersive X-ray (EDX) analysis profiles show that all the mentioned elements are present in the prepared glasses. Following the IR spectra, all the tellurium bonds such as stretching vibrations of TeO4 tbp and TeO3/TeO3+1 unit are revealed. Raman spectra confirm the presence of different functional groups, actually, it shows bands mainly in four spectral regions: R1 (65-150) cm-1, R2 (280-550) cm-1, R3 (880-950) cm-1 and R4 (916-926) cm-1 and the identified bands are assigned to respective molecular groups. The thermal study was carried out using Differential scanning calorimetry (DSC) which indicates good thermal stability of the synthesized glasses with increasing Bi concentration. From the optical absorption spectra, we evaluated cut-off edge wavelengths and found increasing cutoff wavelength with an increase in Bi2O3 concentration. In the UV-Visible region, optical band gap energy and allowed transitions were investigated using three methods; direct, indirect, and absorption spectrum fitting (ASF), and band gaps from indirect and ASF were matched.

MULTI-WAVELENGTH STUDIES OF SPECTACULAR RAM PRESSURE STRIPPING OF A GALAXY: DISCOVERY OF AN X-RAY ABSORPTION FEATURE

SciTech Connect

Gu, Liyi; Makishima, Kazuo; Yagi, Masafumi

We report the detection of an X-ray absorption feature near the galaxy M86 in the Virgo cluster. The absorber has a column density of 2-3 × 10{sup 20} cm{sup –2}, and its position coincides with the peak of an intracluster H I cloud which was removed from the galaxy NGC 4388 presumably by ram pressure. These results indicate that the H I cloud is located in front of M86 along the line-of-sight, and suggest that the stripping was primarily created by an interaction between NGC 4388 and the hot plasmas of the Virgo cluster, not the M86 halo. By calculatingmore » an X-ray temperature map, we further detected an X-ray counterpart of the H I cloud up to ≈3' south of M86. It has a temperature of 0.89 keV and a mass of ∼4.5 × 10{sup 8} M {sub ☉}, exceeding the estimated H I gas mass. The high hot-to-cold gas ratio in the cloud indicates a significant evaporation of the H I gas, probably by thermal conduction from the hotter cluster plasma with a sub-Spitzer rate.« less

Economic indicators selection for crime rates forecasting using cooperative feature selection

NASA Astrophysics Data System (ADS)

Alwee, Razana; Shamsuddin, Siti Mariyam Hj; Salleh Sallehuddin, Roselina

2013-04-01

Features selection in multivariate forecasting model is very important to ensure that the model is accurate. The purpose of this study is to apply the Cooperative Feature Selection method for features selection. The features are economic indicators that will be used in crime rate forecasting model. The Cooperative Feature Selection combines grey relational analysis and artificial neural network to establish a cooperative model that can rank and select the significant economic indicators. Grey relational analysis is used to select the best data series to represent each economic indicator and is also used to rank the economic indicators according to its importance to the crime rate. After that, the artificial neural network is used to select the significant economic indicators for forecasting the crime rates. In this study, we used economic indicators of unemployment rate, consumer price index, gross domestic product and consumer sentiment index, as well as data rates of property crime and violent crime for the United States. Levenberg-Marquardt neural network is used in this study. From our experiments, we found that consumer price index is an important economic indicator that has a significant influence on the violent crime rate. While for property crime rate, the gross domestic product, unemployment rate and consumer price index are the influential economic indicators. The Cooperative Feature Selection is also found to produce smaller errors as compared to Multiple Linear Regression in forecasting property and violent crime rates.

[Study on intestinal absorption features of oligosaccharides in Morinda officinalis How. with sigle-pass perfusion].

PubMed

Deng, Shao-Dong; Zhang, Peng; Lin, Li; Xiao, Feng-Xia; Lin, Jing-Ran

2015-01-01

To study the in situ intestinal absorption of five oligosaccharides contained in Morinda officinalis How. (sucrose, kestose, nystose, 1F-Fructofuranosyinystose and Bajijiasu). The absorption of the five oligosaccharides in small intestine (duodenum, jejunum and ileum) and colon of rats and their contents were investigated by using in situ single-pass perfusion model and HPLC-ELSD. The effects of drug concentration, pH in perfusate and P-glycoprotein inhibitor on the intestinal absorption were investigated to define the intestinal absorption mechanism of the five oligosaccharides in rats. According to the results, all of the five oligosaccharides were absorbed in the whole intestine, and their absorption rates were affected by the pH of the perfusion solution, drug concentration and intestinal segments. Verapamil Hydrochloride could significantly increase the absorptive amount of sucrose and Bajijiasu, suggesting sucrose and Bajijiasu are P-gp's substrate. The five oligosaccharides are absorbed mainly through passive diffusion in the intestinal segments, without saturated absorption. They are absorbed well in all intestines and mainly in duodenum and jejunum.

Cryptography based on the absorption/emission features of multicolor semiconductor nanocrystal quantum dots.

PubMed

Zhou, Ming; Chang, Shoude; Grover, Chander

2004-06-28

Further to the optical coding based on fluorescent semiconductor quantum dots (QDs), a concept of using mixtures of multiple single-color QDs for creating highly secret cryptograms based on their absorption/emission properties was demonstrated. The key to readout of the optical codes is a group of excitation lights with the predetermined wavelengths programmed in a secret manner. The cryptograms can be printed on the surfaces of different objects such as valuable documents for security purposes.

The value of anthropometric indices for identifying women with features of metabolic syndrome

USDA-ARS?s Scientific Manuscript database

BMI is a widely used anthropometric measure for identifying CVD and metabolic syndrome (MetS) risk. Two new anthropometric indices are A Body Shape Index (ABSI) and Body Roundness Index (BRI) that may provide better correlations to features of MetS. Methods: Subject data were obtained from 91 over...

A robust indicator based on singular value decomposition for flaw feature detection from noisy ultrasonic signals

NASA Astrophysics Data System (ADS)

Cui, Ximing; Wang, Zhe; Kang, Yihua; Pu, Haiming; Deng, Zhiyang

2018-05-01

Singular value decomposition (SVD) has been proven to be an effective de-noising tool for flaw echo signal feature detection in ultrasonic non-destructive evaluation (NDE). However, the uncertainty in the arbitrary manner of the selection of an effective singular value weakens the robustness of this technique. Improper selection of effective singular values will lead to bad performance of SVD de-noising. What is more, the computational complexity of SVD is too large for it to be applied in real-time applications. In this paper, to eliminate the uncertainty in SVD de-noising, a novel flaw indicator, named the maximum singular value indicator (MSI), based on short-time SVD (STSVD), is proposed for flaw feature detection from a measured signal in ultrasonic NDE. In this technique, the measured signal is first truncated into overlapping short-time data segments to put feature information of a transient flaw echo signal in local field, and then the MSI can be obtained from the SVD of each short-time data segment. Research shows that this indicator can clearly indicate the location of ultrasonic flaw signals, and the computational complexity of this STSVD-based indicator is significantly reduced with the algorithm proposed in this paper. Both simulation and experiments show that this technique is very efficient for real-time application in flaw detection from noisy data.

Phase-dependent absorption features in X-ray spectra of X-ray Dim Isolated Neutron Stars

NASA Astrophysics Data System (ADS)

Borghese, A.; Rea, N.; Coti Zelati, F.; Turolla, R.; Tiengo, A.; Zane, S.

2017-12-01

A detailed phase-resolved spectroscopy of archival XMM-Newton observations of X-ray Dim Isolated Neutron Stars (XDINSs) led to the discovery of narrow and strongly phase-dependent absorption features in two of these sources. The first was discovered in the X-ray spectrum of RX J0720.4-3125, followed by a new possible candidate in RX J1308.6+2127. Both spectral lines have similar properties: they are detected for only ˜ 20% of the rotational cycle and appear to be stable over the timespan covered by the observations. We performed Monte Carlo simulations to test the significance of these phase-variable features and in both cases the outcome has confirmed the detection with a confidence level > 4.6σ. Because of the narrow width and the strong dependence on the pulsar rotational phase, the most likely interpretation for these spectral features is in terms of resonant proton cyclotron absorption scattering in a confined high-B structure close to the stellar surface. Within the framework of this interpretation, our results provide evidence for deviations from a pure dipole magnetic field on small scales for highly magnetized neutron stars and support the proposed scenario of XDINSs being aged magnetars, with a strong non-dipolar crustal B-field component.

Alternating absorption features during attosecond-pulse propagation in a laser-controlled gaseous medium

NASA Astrophysics Data System (ADS)

Pfeiffer, Adrian N.; Bell, M. Justine; Beck, Annelise R.; Mashiko, Hiroki; Neumark, Daniel M.; Leone, Stephen R.

2013-11-01

Recording the transmitted spectrum of a weak attosecond pulse through a medium, while a strong femtosecond pulse copropagates at variable delay, probes the strong-field dynamics of atoms, molecules, and solids. Usually, the interpretation of these measurements is based on the assumption of a thin medium. Here, the propagation through a macroscopic medium of helium atoms in the region of fully allowed resonances is investigated both theoretically and experimentally. The propagation has dramatic effects on the transient spectrum even at relatively low pressures (50 mbar) and short propagation lengths (1 mm). The absorption does not evolve monotonically with the product of propagation distance and pressure, but regions with characteristics of Lorentz line shapes and characteristics of Fano line shapes alternate. Criteria are deduced to estimate whether macroscopic effects can be neglected or not in a transient absorption experiment. Furthermore, the theory in the limit of single-atom response yields a general equation for Lorentz- and Fano-type line shapes at variable pulse delay.

Retrieval of canopy water content of different crop types with two new hyperspectral indices: Water Absorption Area Index and Depth Water Index

NASA Astrophysics Data System (ADS)

Pasqualotto, Nieves; Delegido, Jesús; Van Wittenberghe, Shari; Verrelst, Jochem; Rivera, Juan Pablo; Moreno, José

2018-05-01

Crop canopy water content (CWC) is an essential indicator of the crop's physiological state. While a diverse range of vegetation indices have earlier been developed for the remote estimation of CWC, most of them are defined for specific crop types and areas, making them less universally applicable. We propose two new water content indices applicable to a wide variety of crop types, allowing to derive CWC maps at a large spatial scale. These indices were developed based on PROSAIL simulations and then optimized with an experimental dataset (SPARC03; Barrax, Spain). This dataset consists of water content and other biophysical variables for five common crop types (lucerne, corn, potato, sugar beet and onion) and corresponding top-of-canopy (TOC) reflectance spectra acquired by the hyperspectral HyMap airborne sensor. First, commonly used water content index formulations were analysed and validated for the variety of crops, overall resulting in a R2 lower than 0.6. In an attempt to move towards more generically applicable indices, the two new CWC indices exploit the principal water absorption features in the near-infrared by using multiple bands sensitive to water content. We propose the Water Absorption Area Index (WAAI) as the difference between the area under the null water content of TOC reflectance (reference line) simulated with PROSAIL and the area under measured TOC reflectance between 911 and 1271 nm. We also propose the Depth Water Index (DWI), a simplified four-band index based on the spectral depths produced by the water absorption at 970 and 1200 nm and two reference bands. Both the WAAI and DWI outperform established indices in predicting CWC when applied to heterogeneous croplands, with a R2 of 0.8 and 0.7, respectively, using an exponential fit. However, these indices did not perform well for species with a low fractional vegetation cover (<30%). HyMap CWC maps calculated with both indices are shown for the Barrax region. The results confirmed the

Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+64. 3.1

NASA Technical Reports Server (NTRS)

Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.;

Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+641. 2.5

NASA Technical Reports Server (NTRS)

Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.;

Searches for 3.5 keV Absorption Features in Cluster AGN Spectra

NASA Astrophysics Data System (ADS)

Conlon, Joseph P.

2018-06-01

We investigate possible evidence for a spectral dip around 3.5 keV in central cluster AGNs, motivated by previous results for archival Chandra observations of the Perseus cluster and the general interest in novel spectral features around 3.5 keV that may arise from dark matter physics. We use two deep Chandra observations of the Perseus and Virgo clusters that have recently been made public. In both cases, mild improvements in the fit (Δχ2 = 4.2 and Δχ2 = 2.5) are found by including such a dip at 3.5 keV into the spectrum. A comparable result (Δχ2 = 6.5) is found re-analysing archival on-axis Chandra ACIS-S observations of the centre of the Perseus cluster.

Denivation Features of Polar Dunes: An Earth Analogue for Morphological Indicators of Solid Water on Mars

NASA Astrophysics Data System (ADS)

McGowan, H. A.; Neil, D.

2005-12-01

The identification of sources of water on Mars will be critical to the successful exploration of the planet and the establishment of a permanent presence by humans. While the Martian polar ice caps contain up to 70% water by mass, the extreme climate of these regions means that they may not be suitable for habitation. As a result, other sites must be identified where access to water is possible. Recent evidence has emerged that suggests sand dunes on Mars may contain 40-50% water by mass (Bourke 2005). In this paper, we present niveo-aeolian features observed in the sand dunes of the Victoria Valley, Antarctica, which have long been considered an Earth analogue for those on Mars (Morris et al. 1972). These features include cornices of permafrosted sand in dune-crest deflation hollows, exposed erosion resistant frozen water and sand lenses, wet sand flows and seeps. We also report on the morphological characteristics of sand sink holes which form in chains above layers of buried, melting and/or sublimating snow. This process is apparently reliant on the melting of inter-grain ice bonds and subsequent formation of a dry mobile sand layer on the dune surface. These micro-morphological features associated with summertime denivation of the Victoria Valley sand dunes, which are 5 to 10 m high and several hundred meters in crest length, are too small to identify on air photographs, satellite imagery and LIDAR DEMS of these transverse barchanoid ridges. However, on Mars where sand dunes are 1 to 2 orders of magnitude larger, these features may be identifiable if solid water exists within them, as suggested by Bourke (2005). Perhaps of greater importance, they may indicate the presence of buried palaeo-snow layers which have been preserved beneath the erosion resistant permafrosted sand dunes on Mars. We believe that the formation and subsequent exposure of these snow layers is the primary cause of the denivation features present in the polar dunes of the Victoria Valley

Identifying Features of Bodily Expression As Indicators of Emotional Experience during Multimedia Learning

PubMed Central

Riemer, Valentin; Frommel, Julian; Layher, Georg; Neumann, Heiko; Schrader, Claudia

2017-01-01

The importance of emotions experienced by learners during their interaction with multimedia learning systems, such as serious games, underscores the need to identify sources of information that allow the recognition of learners’ emotional experience without interrupting the learning process. Bodily expression is gaining in attention as one of these sources of information. However, to date, the question of how bodily expression can convey different emotions has largely been addressed in research relying on acted emotion displays. Following a more contextualized approach, the present study aims to identify features of bodily expression (i.e., posture and activity of the upper body and the head) that relate to genuine emotional experience during interaction with a serious game. In a multimethod approach, 70 undergraduates played a serious game relating to financial education while their bodily expression was captured using an off-the-shelf depth-image sensor (Microsoft Kinect). In addition, self-reports of experienced enjoyment, boredom, and frustration were collected repeatedly during gameplay, to address the dynamic changes in emotions occurring in educational tasks. Results showed that, firstly, the intensities of all emotions indeed changed significantly over the course of the game. Secondly, by using generalized estimating equations, distinct features of bodily expression could be identified as significant indicators for each emotion under investigation. A participant keeping their head more turned to the right was positively related to frustration being experienced, whereas keeping their head more turned to the left was positively related to enjoyment. Furthermore, having their upper body positioned more closely to the gaming screen was also positively related to frustration. Finally, increased activity of a participant’s head emerged as a significant indicator of boredom being experienced. These results confirm the value of bodily expression as an indicator

Visual feature integration indicated by pHase-locked frontal-parietal EEG signals.

PubMed

Phillips, Steven; Takeda, Yuji; Singh, Archana

2012-01-01

The capacity to integrate multiple sources of information is a prerequisite for complex cognitive ability, such as finding a target uniquely identifiable by the conjunction of two or more features. Recent studies identified greater frontal-parietal synchrony during conjunctive than non-conjunctive (feature) search. Whether this difference also reflects greater information integration, rather than just differences in cognitive strategy (e.g., top-down versus bottom-up control of attention), or task difficulty is uncertain. Here, we examine the first possibility by parametrically varying the number of integrated sources from one to three and measuring phase-locking values (PLV) of frontal-parietal EEG electrode signals, as indicators of synchrony. Linear regressions, under hierarchical false-discovery rate control, indicated significant positive slopes for number of sources on PLV in the 30-38 Hz, 175-250 ms post-stimulus frequency-time band for pairs in the sagittal plane (i.e., F3-P3, Fz-Pz, F4-P4), after equating conditions for behavioural performance (to exclude effects due to task difficulty). No such effects were observed for pairs in the transverse plane (i.e., F3-F4, C3-C4, P3-P4). These results provide support for the idea that anterior-posterior phase-locking in the lower gamma-band mediates integration of visual information. They also provide a potential window into cognitive development, seen as developing the capacity to integrate more sources of information.

Spectroscopic remote sensing of plant stress at leaf and canopy levels using the chlorophyll 680 nm absorption feature with continuum removal

USGS Publications Warehouse

Sanches, Ieda Del´Arco; Souza Filho, Carlos Roberto de; Kokaly, Raymond F.

2014-01-01

This paper explores the use of spectral feature analysis to detect plant stress in visible/near infrared wavelengths. A time series of close range leaf and canopy reflectance data of two plant species grown in hydrocarbon-contaminated soil was acquired with a portable spectrometer. The ProSpecTIR-VS airborne imaging spectrometer was used to obtain far range hyperspectral remote sensing data over the field experiment. Parameters describing the chlorophyll 680 nm absorption feature (depth, width, and area) were derived using continuum removal applied to the spectra. A new index, the Plant Stress Detection Index (PSDI), was calculated using continuum-removed values near the chlorophyll feature centre (680 nm) and on the green-edge (560 and 575 nm). Chlorophyll feature’s depth, width and area, the PSDI and a narrow-band normalised difference vegetation index were evaluated for their ability to detect stressed plants. The objective was to analyse how the parameters/indices were affected by increasing degrees of plant stress and to examine their utility as plant stress indicators at the remote sensing level (e.g. airborne sensor). For leaf data, PSDI and the chlorophyll feature area revealed the highest percentage (67–70%) of stressed plants. The PSDI also proved to be the best constraint for detecting the stress in hydrocarbon-impacted plants with field canopy spectra and airborne imaging spectroscopy data. This was particularly true using thresholds based on the ASD canopy data and considering the combination of higher percentage of stressed plants detected (across the thresholds) and fewer false-positives.

Visual Feature Integration Indicated by pHase-Locked Frontal-Parietal EEG Signals

PubMed Central

Phillips, Steven; Takeda, Yuji; Singh, Archana

2012-01-01

The capacity to integrate multiple sources of information is a prerequisite for complex cognitive ability, such as finding a target uniquely identifiable by the conjunction of two or more features. Recent studies identified greater frontal-parietal synchrony during conjunctive than non-conjunctive (feature) search. Whether this difference also reflects greater information integration, rather than just differences in cognitive strategy (e.g., top-down versus bottom-up control of attention), or task difficulty is uncertain. Here, we examine the first possibility by parametrically varying the number of integrated sources from one to three and measuring phase-locking values (PLV) of frontal-parietal EEG electrode signals, as indicators of synchrony. Linear regressions, under hierarchical false-discovery rate control, indicated significant positive slopes for number of sources on PLV in the 30–38 Hz, 175–250 ms post-stimulus frequency-time band for pairs in the sagittal plane (i.e., F3-P3, Fz-Pz, F4-P4), after equating conditions for behavioural performance (to exclude effects due to task difficulty). No such effects were observed for pairs in the transverse plane (i.e., F3-F4, C3-C4, P3-P4). These results provide support for the idea that anterior-posterior phase-locking in the lower gamma-band mediates integration of visual information. They also provide a potential window into cognitive development, seen as developing the capacity to integrate more sources of information. PMID:22427847

TOWARD DETECTING THE 2175 A DUST FEATURE ASSOCIATED WITH STRONG HIGH-REDSHIFT Mg II ABSORPTION LINES

SciTech Connect

Jiang Peng; Zhou Hongyan; Wang Junxian

2011-05-10

We report detections of 39 2175 A dust extinction bump candidates associated with strong Mg II absorption lines at z{approx} 1-1.8 on quasar spectra in Sloan Digital Sky Survey (SDSS) DR3. These strong Mg II absorption line systems are detected among 2951 strong Mg II absorbers with a rest equivalent width W{sub r} {lambda}2796> 1.0 A at 1.0 < z < 1.86, which is part of a full sample of 7421 strong Mg II absorbers compiled by Prochter et al. The redshift range of the absorbers is chosen to allow the 2175 A extinction features to be completely covered withinmore » the SDSS spectrograph operation wavelength range. An upper limit of the background quasar emission redshift at z = 2.1 is set to prevent the Ly{alpha} forest lines from contaminating the sensitive spectral region for the 2175 A bump measurements. The FM90 parameterization is applied to model the optical/UV extinction curve in the rest frame of Mg II absorbers of the 2175 A bump candidates. The simulation technique developed by Jiang et al. is used to derive the statistical significance of the candidate 2175 A bumps. A total of 12 absorbers are detected with 2175 A bumps at a 5{sigma} level of statistical significance, 10 are detected at a 4{sigma} level, and 17 are detected at a 3{sigma} level. Most of the candidate bumps in this work are similar to the relatively weak 2175 A bumps observed in the Large Magellanic Cloud LMC2 supershell rather than the strong ones observed in the Milky Way. This sample has greatly increased the total number of 2175 A extinction bumps measured on SDSS quasar spectra. Follow-up observations may rule out some of the possible false detections and reveal the physical and chemical natures of 2175 A quasar absorbers.« less

Toward Detecting the 2175 Å Dust Feature Associated with Strong High-redshift Mg II Absorption Lines

NASA Astrophysics Data System (ADS)

Jiang, Peng; Ge, Jian; Zhou, Hongyan; Wang, Junxian; Wang, Tinggui

2011-05-01

We report detections of 39 2175 Å dust extinction bump candidates associated with strong Mg II absorption lines at z~ 1-1.8 on quasar spectra in Sloan Digital Sky Survey (SDSS) DR3. These strong Mg II absorption line systems are detected among 2951 strong Mg II absorbers with a rest equivalent width Wr λ2796> 1.0 Å at 1.0 < z < 1.86, which is part of a full sample of 7421 strong Mg II absorbers compiled by Prochter et al. The redshift range of the absorbers is chosen to allow the 2175 Å extinction features to be completely covered within the SDSS spectrograph operation wavelength range. An upper limit of the background quasar emission redshift at z = 2.1 is set to prevent the Lyα forest lines from contaminating the sensitive spectral region for the 2175 Å bump measurements. The FM90 parameterization is applied to model the optical/UV extinction curve in the rest frame of Mg II absorbers of the 2175 Å bump candidates. The simulation technique developed by Jiang et al. is used to derive the statistical significance of the candidate 2175 Å bumps. A total of 12 absorbers are detected with 2175 Å bumps at a 5σ level of statistical significance, 10 are detected at a 4σ level, and 17 are detected at a 3σ level. Most of the candidate bumps in this work are similar to the relatively weak 2175 Å bumps observed in the Large Magellanic Cloud LMC2 supershell rather than the strong ones observed in the Milky Way. This sample has greatly increased the total number of 2175 Å extinction bumps measured on SDSS quasar spectra. Follow-up observations may rule out some of the possible false detections and reveal the physical and chemical natures of 2175 Å quasar absorbers.

FE K EMISSION AND ABSORPTION FEATURES IN THE XMM-EPIC SPECTRUM OF THE SEYFERT GALAXY IC 4329A

NASA Technical Reports Server (NTRS)

Markowitz, A.; Reeves, J. N.; Braito, V.

2001-01-01

We present a re-analysis of the XMM-Newton long-look of the X-ray bright Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two peaks, consistent with emission from neutral or near-neutral Fe Ka and KP. A relativistic diskline model whereby both peaks are the result of one doubly-peaked diskline profile is found to be a poor description of the data. Models using two relativistic disklines are found to describe the emission profile well. A low-inclination, moderately-relativistic dual-diskline model is possible if the contribution from narrow components, due to distant material, is small or absent. A high-inclination, moderately relativistic profile for each peak is possible if there are roughly equal contributions from both the broad and narrow components. Upper limits on Fe XXV and Fe XXVI emission and absorption at the systemic velocity of IC 4329a are obtained. We also present the results of RXTE monitoring of this source obtained so far; the combined XMM-Newton and RXTE data sets allow us to explore the time-resolved spectral behavior of this source on time scales ranging from hours to 2 years. We find no strong evidence for variability of the Fe Ka emission line on any time scale probed, likely due to the minimal level of continuum variability. We detect a narrow absorption line, at a energy of 7.68 keV in the rest frame of the source; its significance has been confirmed using Monte Carlo simulations. This feature is most likely due to absorption from Fe XXVI blueshifted to approximately 0.1c relative to the systemic velocity, making IC 4329a the lowest-redshift AGN known with a high-velocity, highly-ionized outflow component. As is often the case with similar outflows seen in high-luminosity quasars, the estimated mass outflow rate is larger than the inflow accretion rate, signaling that the outflow represents a substantial portion of the total energy budget of the AGN. The outflow could arise from a radiatively-driven disk wind, or it may be in the

Constraints on the OH-to-H Abundance Ratio in Infrared-bright Galaxies Derived from the Strength of the OH 35 μm Absorption Feature

NASA Astrophysics Data System (ADS)

Stone, Myra; Veilleux, Sylvain; González-Alfonso, Eduardo; Spoon, Henrik; Sturm, Eckhard

2018-02-01

We analyze Spitzer/InfraRed Spectrograph (IRS) observations of the OH 35 μm feature in 15 nearby (z ≲ 0.06) (ultra-)luminous infrared galaxies (U/LIRGs). All objects exhibit OH 35 μm purely in absorption, as expected. The small optical depth of this transition makes the strength of this feature a good indicator of the true OH column density. The measured OH 35 μm equivalent widths imply an average OH column density and a 1-σ standard deviation to the mean of {N}{OH}=1.31+/- 0.22× {10}17 cm‑2. This number is then compared with the hydrogen column density for a typical optical depth at 35 μm of ∼0.5 and gas-to-dust ratio of 125 to derive an OH-to-H abundance ratio of {X}{OH}=1.01+/- 0.15× {10}-6. This abundance ratio is formally a lower limit. It is consistent with the values generally assumed in the literature. The OH 35 μm line profiles predicted from published radiative transfer models constrained by observations of OH 65, 79, 84, and 119 μm in 5 objects (Mrk 231, Mrk 273, IRAS F05189-2524, IRAS F08572+3915, and IRAS F20551-4250) are also found to be consistent with the IRS OH 35 μm spectra.

Environmental Temperature Effect on the Far-Infrared Absorption Features of Aromatic-Based Titan's Aerosol Analogs

NASA Technical Reports Server (NTRS)

Gautier, Thomas; Trainer, Melissa G.; Loeffler, Mark J.; Sebree, Joshua A.; Anderson, Carrie M.

2016-01-01

Benzene detection has been reported in Titans atmosphere both in the stratosphere at ppb levels by remote sensing and in the thermosphere at ppm levels by the Cassini's Ion and Neutral Mass Spectrometer. This detection supports the idea that aromatic and heteroaromatic reaction pathways may play an important role in Titans atmospheric chemistry, especially in the formation of aerosols. Indeed, aromatic molecules are easily dissociated by ultraviolet radiation and can therefore contribute significantly to aerosol formation. It has been shown recently that aerosol analogs produced from a gas mixture containing a low concentration of aromatic and/or heteroaromatic molecules (benzene, naphthalene, pyridine, quinoline and isoquinoline) have spectral signatures below 500/cm, a first step towards reproducing the aerosol spectral features observed by Cassini's Composite InfraRed Spectrometer (CIRS) in the far infrared. In this work we investigate the influence of environmental temperature on the absorption spectra of such aerosol samples, simulating the temperature range to which aerosols, once formed, are exposed during their transport through Titans stratosphere. Our results show that environmental temperature does not have any major effect on the spectral shape of these aerosol analogs in the far-infrared, which is consistent with the CIRS observations.

Environmental temperature effect on the far-infrared absorption features of aromatic-based Titan's aerosol analogs

NASA Astrophysics Data System (ADS)

Gautier, Thomas; Trainer, Melissa G.; Loeffler, Mark J.; Sebree, Joshua A.; Anderson, Carrie M.

2017-01-01

Benzene detection has been reported in Titan's atmosphere both in the stratosphere at ppb levels by remote sensing (Coustenis et al., 2007; Vinatier et al., 2007) and in the thermosphere at ppm levels by the Cassini's Ion and Neutral Mass Spectrometer (Waite et al., 2007). This detection supports the idea that aromatic and heteroaromatic reaction pathways may play an important role in Titan's atmospheric chemistry, especially in the formation of aerosols. Indeed, aromatic molecules are easily dissociated by ultraviolet radiation and can therefore contribute significantly to aerosol formation. It has been shown recently that aerosol analogs produced from a gas mixture containing a low concentration of aromatic and/or heteroaromatic molecules (benzene, naphthalene, pyridine, quinoline and isoquinoline) have spectral signatures below 500 cm-1, a first step towards reproducing the aerosol spectral features observed by Cassini's Composite InfraRed Spectrometer (CIRS) in the far infrared (Anderson and Samuelson 2011, and references therein). In this work we investigate the influence of environmental temperature on the absorption spectra of such aerosol samples, simulating the temperature range to which aerosols, once formed, are exposed during their transport through Titan's stratosphere. Our results show that environmental temperature does not have any major effect on the spectral shape of these aerosol analogs in the far-infrared, which is consistent with the CIRS observations.

Absorption features of chromophoric dissolved organic matter (CDOM) and tracing implication for dissolved organic carbon (DOC) in Changjiang Estuary, China

NASA Astrophysics Data System (ADS)

Zhang, X. Y.; Chen, X.; Deng, H.; Du, Y.; Jin, H. Y.

2013-07-01

Chromophoric dissolved organic matter (CDOM) represents the light absorbing fraction of dissolved organic carbon (DOC). Studies have shown that the optical properties of CDOM can be used to infer the distribution and diffusion characteristics of DOC in the estuary and coastal zone. The inversion of DOC concentrations from remote sensing has been implemented in certain regions. In this study we investigate the potential of tracing DOC from CDOM by the measurement of DOC, absorption spectrum of CDOM, Chla concentration, suspended sediment (SS), and salinity from cruises in different seasons around the Changjiang estuary. Our results show that around the Changjiang estuary the absorption coefficients of CDOM in general have the similar spatial and temporal characteristics as that of DOC, but the strength of the correlation between CDOM and DOC varies locally and seasonally. The input of pollutants from outside the estuary, the bloom of phytoplankton in spring, re-suspension of deposited sediment, and light bleaching all contribute to the local and seasonal variation of the correlation between DOC and CDOM. An inversion model for the determination of DOC from CDOM is established, but the stability of model parameters and its application in different environments need further study. We find that relative to the absorption coefficient of CDOM, the fitted parameters of the absorption spectrum of DOM are better indictors for the composition of DOC. In addition, it is found that the terrestrial input of DOC to Changjiang estuary is a typical two-stage dilution process instead of a linear diffusion process.

Wetting of nonconserved residue-backbones: A feature indicative of aggregation associated regions of proteins.

PubMed

Pradhan, Mohan R; Pal, Arumay; Hu, Zhongqiao; Kannan, Srinivasaraghavan; Chee Keong, Kwoh; Lane, David P; Verma, Chandra S

2016-02-01

Aggregation is an irreversible form of protein complexation and often toxic to cells. The process entails partial or major unfolding that is largely driven by hydration. We model the role of hydration in aggregation using "Dehydrons." "Dehydrons" are unsatisfied backbone hydrogen bonds in proteins that seek shielding from water molecules by associating with ligands or proteins. We find that the residues at aggregation interfaces have hydrated backbones, and in contrast to other forms of protein-protein interactions, are under less evolutionary pressure to be conserved. Combining evolutionary conservation of residues and extent of backbone hydration allows us to distinguish regions on proteins associated with aggregation (non-conserved dehydron-residues) from other interaction interfaces (conserved dehydron-residues). This novel feature can complement the existing strategies used to investigate protein aggregation/complexation. © 2015 Wiley Periodicals, Inc.

Exploratory normalized difference water indices for semi-automated extraction of Antarctic lake features

NASA Astrophysics Data System (ADS)

Jawak, Shridhar D.; Luis, Alvarinho J.

2016-05-01

This work presents various normalized difference water indices (NDWI) to delineate lakes from Schirmacher Oasis, East Antarctica, by using a very high resolution WorldView-2 (WV-2) satellite imagery. Schirmacher oasis region hosts a number of fresh as well as saline water lakes, such as epishelf lakes, ice-free or landlocked lakes, which are completely frozen or semi-frozen and in a ice-free state. Hence, detecting all these types of lakes distinctly on satellite imagery was the major challenge, as the spectral characteristics of various types of lakes were identical to the other land cover targets. Multiband spectral index pixel-based approach is most experimented and recently growing technique because of its unbeatable advantages such as its simplicity and comparatively lesser amount of processing-time. In present study, semiautomatic extraction of lakes in cryospheric region was carried out by designing specific spectral indices. The study utilized number of existing spectral indices to extract lakes but none could deliver satisfactory results and hence we modified NDWI. The potentials of newly added bands in WV-2 satellite imagery was explored by developing spectral indices comprising of Yellow (585 - 625 nm) band, in combination with Blue (450 - 510 nm), Coastal (400 - 450 nm) and Green (510 - 580 nm) bands. For extraction of frozen lakes, use of Yellow (585 - 625 nm) and near-infrared 2 (NIR2) band pair, and Yellow and Green band pair worked well, whereas for ice-free lakes extraction, a combination of Blue and Coastal band yielded appreciable results, when compared with manually digitized data. The results suggest that the modified NDWI approach rendered bias error varying from 1 to 34 m2.

Study of Radiographic Linear Indications and Subsequent Microstructural Features in Gas Tungsten Arc Welds of Inconel 718

NASA Technical Reports Server (NTRS)

Walley, J. L.; Nunes, A. C.; Clounch, J. L.; Russell, C. K.

2007-01-01

This study presents examples and considerations for differentiating linear radiographic indications produced by gas tungsten arc welds in a 0.05-in-thick sheet of Inconel 718. A series of welds with different structural features, including the enigma indications and other defect indications such as lack of fusion and penetration, were produced, radiographed, and examined metallographically. The enigma indications were produced by a large columnar grain running along the center of the weld nugget occurring when the weld speed was reduced sufficiently below nominal. Examples of respective indications, including the effect of changing the x-ray source location, are presented as an aid to differentiation. Enigma, nominal, and hot-weld specimens were tensile tested to demonstrate the harmlessness of the enigma indication. Statistical analysis showed that there is no difference between the strengths of these three weld conditions.

FIRST ULTRAVIOLET REFLECTANCE SPECTRA OF PLUTO AND CHARON BY THE HUBBLE SPACE TELESCOPE COSMIC ORIGINS SPECTROGRAPH: DETECTION OF ABSORPTION FEATURES AND EVIDENCE FOR TEMPORAL CHANGE

SciTech Connect

Stern, S. A.; Spencer, J. R.; Shinn, A.

We have observed the mid-UV spectra of both Pluto and its large satellite, Charon, at two rotational epochs using the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) in 2010. These are the first HST/COS measurements of Pluto and Charon. Here we describe the observations and our reduction of them, and present the albedo spectra, average mid-UV albedos, and albedo slopes we derive from these data. These data reveal evidence for a strong absorption feature in the mid-UV spectrum of Pluto; evidence for temporal change in Pluto's spectrum since the 1990s is reported, and indirect evidence for a near-UV spectralmore » absorption on Charon is also reported.« less

Comparative Analysis of Vertebrate Dystrophin Loci Indicate Intron Gigantism as a Common Feature

PubMed Central

Pozzoli, Uberto; Elgar, Greg; Cagliani, Rachele; Riva, Laura; Comi, Giacomo P.; Bresolin, Nereo; Bardoni, Alessandra; Sironi, Manuela

2003-01-01

The human DMD gene is the largest known to date, spanning > 2000 kb on the X chromosome. The gene size is mainly accounted for by huge intronic regions. We sequenced 190 kb of Fugu rubripes (pufferfish) genomic DNA corresponding to the complete dystrophin gene (FrDMD) and provide the first report of gene structure and sequence comparison among dystrophin genomic sequences from different vertebrate organisms. Almost all intron positions and phases are conserved between FrDMD and its mammalian counterparts, and the predicted protein product of the Fugu gene displays 55% identity and 71% similarity to human dystrophin. In analogy to the human gene, FrDMD presents several-fold longer than average intronic regions. Analysis of intron sequences of the human and murine genes revealed that they are extremely conserved in size and that a similar fraction of total intron length is represented by repetitive elements; moreover, our data indicate that intron expansion through repeat accumulation in the two orthologs is the result of independent insertional events. The hypothesis that intron length might be functionally relevant to the DMD gene regulation is proposed and substantiated by the finding that dystrophin intron gigantism is common to the three vertebrate genes. [Supplemental material is available online at www.genome.org.] PMID:12727896

High sensitivity liquid phase measurements using broadband cavity enhanced absorption spectroscopy (BBCEAS) featuring a low cost webcam based prism spectrometer.

PubMed

Qu, Zhechao; Engstrom, Julia; Wong, Donald; Islam, Meez; Kaminski, Clemens F

2013-11-07

Cavity enhanced techniques enable high sensitivity absorption measurements in the liquid phase but are typically more complex, and much more expensive, to perform than conventional absorption methods. The latter attributes have so far prevented a wide spread use of these methods in the analytical sciences. In this study we demonstrate a novel BBCEAS instrument that is sensitive, yet simple and economical to set up and operate. We use a prism spectrometer with a low cost webcam as the detector in conjunction with an optical cavity consisting of two R = 0.99 dielectric mirrors and a white light LED source for illumination. High sensitivity liquid phase measurements were made on samples contained in 1 cm quartz cuvettes placed at normal incidence to the light beam in the optical cavity. The cavity enhancement factor (CEF) with water as the solvent was determined directly by phase shift cavity ring down spectroscopy (PS-CRDS) and also by calibration with Rhodamine 6G solutions. Both methods yielded closely matching CEF values of ~60. The minimum detectable change in absorption (αmin) was determined to be 6.5 × 10(-5) cm(-1) at 527 nm and was limited only by the 8 bit resolution of the particular webcam detector used, thus offering scope for further improvement. The instrument was used to make representative measurements on dye solutions and in the determination of nitrite concentrations in a variation of the widely used Griess Assay. Limits of detection (LOD) were ~850 pM for Rhodamine 6G and 3.7 nM for nitrite, respectively. The sensitivity of the instrument compares favourably with previous cavity based liquid phase studies whilst being achieved at a small fraction of the cost hitherto reported, thus opening the door to widespread use in the community. Further means of improving sensitivity are discussed in the paper.

Development of an extended-range fiber optic pH sensor using evanescent wave absorption of sol-gel-entrapped pH indicators

NASA Astrophysics Data System (ADS)

Butler, Thomas M.; MacCraith, Brian D.; McDonagh, Colette M.

1995-09-01

The sol-gel process has been used to entrap pH indicators in porous glass coatings for sensor applications. This sensor is based on evanescent wave absorption using an unclad optical fiber dipcoated with the pH sensitive coating. The entrapped pH indicators show a broadening of the pH range with respect to the behavior in solution giving accurate measurement over three pH units when one indicator is used (bromophenol blue) and over six pH units (pH 3-9) when two indicators are used (bromophenol blue and bromocresol purple). The response of the pH sensor was monitored by measuring absorption at 590 nm referenced against a nonabsorbing region of the spectrum. This enabled the use of LED sources together with low cost photodiodes. The sensor displayed short response time and good repeatability. The thickness and stability of the pH sensitive coatings can be influenced by modifying the composition of the starting sol mixture. The evanescent absorption, and hence the sensitivity of the sensor, can be increased by selectively launching higher order modes in the fiber. These issues together with a full sensor characterization will be reported.

Digital soil mapping using remote sensing indices, terrain attributes, and vegetation features in the rangelands of northeastern Iran.

PubMed

Mahmoudabadi, Ebrahim; Karimi, Alireza; Haghnia, Gholam Hosain; Sepehr, Adel

2017-09-11

Digital soil mapping has been introduced as a viable alternative to the traditional mapping methods due to being fast and cost-effective. The objective of the present study was to investigate the capability of the vegetation features and spectral indices as auxiliary variables in digital soil mapping models to predict soil properties. A region with an area of 1225 ha located in Bajgiran rangelands, Khorasan Razavi province, northeastern Iran, was chosen. A total of 137 sampling sites, each containing 3-5 plots with 10-m interval distance along a transect established based on randomized-systematic method, were investigated. In each plot, plant species names and numbers as well as vegetation cover percentage (VCP) were recorded, and finally one composite soil sample was taken from each transect at each site (137 soil samples in total). Terrain attributes were derived from a digital elevation model, different bands and spectral indices were obtained from the Landsat7 ETM+ images, and vegetation features were calculated in the plots, all of which were used as auxiliary variables to predict soil properties using artificial neural network, gene expression programming, and multivariate linear regression models. According to R 2 RMSE and MBE values, artificial neutral network was obtained as the most accurate soil properties prediction function used in scorpan model. Vegetation features and indices were more effective than remotely sensed data and terrain attributes in predicting soil properties including calcium carbonate equivalent, clay, bulk density, total nitrogen, carbon, sand, silt, and saturated moisture capacity. It was also shown that vegetation indices including NDVI, SAVI, MSAVI, SARVI, RDVI, and DVI were more effective in estimating the majority of soil properties compared to separate bands and even some soil spectral indices.

L-Asparagine crystals with wide gap semiconductor features: optical absorption measurements and density functional theory computations.

PubMed

Zanatta, G; Gottfried, C; Silva, A M; Caetano, E W S; Sales, F A M; Freire, V N

2014-03-28

Results of optical absorption measurements are presented together with calculated structural, electronic, and optical properties for the anhydrous monoclinic L-asparagine crystal. Density functional theory (DFT) within the generalized gradient approximation (GGA) including dispersion effects (TS, Grimme) was employed to perform the calculations. The optical absorption measurements revealed that the anhydrous monoclinic L-asparagine crystal is a wide band gap material with 4.95 eV main gap energy. DFT-GGA+TS simulations, on the other hand, produced structural parameters in very good agreement with X-ray data. The lattice parameter differences Δa, Δb, Δc between theory and experiment were as small as 0.020, 0.051, and 0.022 Å, respectively. The calculated band gap energy is smaller than the experimental data by about 15%, with a 4.23 eV indirect band gap corresponding to Z → Γ and Z → β transitions. Three other indirect band gaps of 4.30 eV, 4.32 eV, and 4.36 eV are assigned to α3 → Γ, α1 → Γ, and α2 → Γ transitions, respectively. Δ-sol computations, on the other hand, predict a main band gap of 5.00 eV, just 50 meV above the experimental value. Electronic wavefunctions mainly originating from O 2p-carboxyl, C 2p-side chain, and C 2p-carboxyl orbitals contribute most significantly to the highest valence and lowest conduction energy bands, respectively. By varying the lattice parameters from their converged equilibrium values, we show that the unit cell is less stiff along the b direction than for the a and c directions. Effective mass calculations suggest that hole transport behavior is more anisotropic than electron transport, but the mass values allow for some charge mobility except along a direction perpendicular to the molecular layers of L-asparagine which form the crystal, so anhydrous monoclinic L-asparagine crystals could behave as wide gap semiconductors. Finally, the calculations point to a high degree of optical

Crowdsourcing Broad Absorption Line Properties and Other Features of Quasar Outflow Using Zooniverse Citizen Science Project Platform

NASA Astrophysics Data System (ADS)

Crowe, Cassie; Lundgren, Britt; Grier, Catherine

2018-01-01

The Sloan Digital Sky Survey (SDSS) regularly publishes vast catalogs of quasars and other astronomical objects. Previously, the SDSS collaboration has used visual inspection to check quasar redshift validity and flag instances of broad absorption lines (BALs). This information helps researchers to easily single out the quasars with BAL properties and study their outflows and other intervening gas clouds. Due to the ever-growing number of new SDSS quasar observations, visual inspections are no longer possible using previous methods. Currently, BAL information is being determined entirely computationally, and the accuracy of that information is not precisely known. This project uses the Zooniverse citizen science platform to visually inspect quasar spectra for BAL properties, to check the accuracy of the current autonomous methods, and to flag multi-phase outflows and find candidates for in-falling gas into the quasar central engine. The layout and format of a Zooniverse project provides an easier way to inspect and record data on each spectrum and share the workload via crowdsourcing. Work done by the SDSS collaboration members is serving as a beta test for a public project upon the official release of the DR14 quasar catalog by SDSS.

Absorption features in the quasar HS 1603 + 3820 II. Distance to the absorber obtained from photoionisation modelling

NASA Astrophysics Data System (ADS)

Różańska, A.; Nikołajuk, M.; Czerny, B.; Dobrzycki, A.; Hryniewicz, K.; Bechtold, J.; Ebeling, H.

2014-04-01

We present the photoionisation modelling of the intrinsic absorber in the bright quasar HS 1603 + 3820. We constructed the broad-band spectral energy distribution using the optical/UV/X-ray observations from different instruments as inputs for the photoionisation calculations. The spectra from the Keck telescope show extremely high CIV to HI ratios, for the first absorber in system A, named A1. This value, together with high column density of CIV ion, place strong constraints on the photoionisation model. We used two photoionisation codes to derive the hydrogen number density at the cloud illuminated surface. By estimating bolometric luminosity of HS 1603 + 3820 using the typical formula for quasars, we calculated the distance to A1. We could find one photoionization solution, by assuming either a constant density cloud (which was modelled using CLOUDY), or a stratified cloud (which was modelled using TITAN), as well as the solar abundances. This model explained both the ionic column density of CIV and the high CIV to HI ratio. The location of A1 is 0.1 pc, and it is situated even closer to the nucleus than the possible location of the Broad Line Region in this object. The upper limit of the distance is sensitive to the adopted covering factor and the carbon abundance. Photoionisation modelling always prefers dense clouds with the number density n0 = 1010 - 1012 cm-3, which explains intrinsic absorption in HS 1603 + 3820. This number density is of the same order as that in the disk atmosphere at the implied distance of A1. Therefore, our results show that the disk wind that escapes from the outermost accretion disk atmosphere can build up dense absorber in quasars.

Assignment of Pre-edge Features in the Ru K-edge X-ray Absorption Spectra of Organometallic Ruthenium Complexes

PubMed Central

Getty, Kendra; Delgado-Jaime, Mario Ulises

2010-01-01

The nature of the lowest energy bound-state transition in the Ru K-edge X-ray Absorption Spectra for a series of Grubbs-type ruthenium complexes was investigated. The pre-edge feature was unambiguously assigned as resulting from formally electric dipole forbidden Ru 4d←1s transitions. The intensities of these transitions are extremely sensitive to the ligand environment and the symmetry of the metal centre. In centrosymmetric complexes the pre-edge is very weak since it is limited by the weak electric quadrupole intensity mechanism. By contrast, upon breaking centrosymmetry, Ru 5p-4d mixing allows for introduction of electric dipole allowed character resulting in a dramatic increase in the pre-edge intensity. The information content of this approach is explored as it relates to complexes of importance in olefin metathesis and its relevance as a tool for the study of reactive intermediates. PMID:20151030

Emotional, behavioral, and developmental features indicative of neglect or emotional abuse in preschool children: a systematic review.

PubMed

Naughton, Aideen Mary; Maguire, Sabine Ann; Mann, Mala Kanthi; Lumb, Rebecca Caroline; Tempest, Vanessa; Gracias, Shirley; Kemp, Alison Mary

2013-08-01

Early intervention for neglect or emotional abuse in preschoolers may mitigate lifelong consequences, yet practitioners lack confidence in recognizing these children. To define the emotional, behavioral, and developmental features of neglect or emotional abuse in preschoolers. A literature search of 18 databases, 6 websites, and supplementary searching performed from January 1, 1960, to February 1, 2011, identified 22 669 abstracts. Standardized critical appraisal of 164 articles was conducted by 2 independent, trained reviewers. Inclusion criteria were children aged 0 to 6 years with confirmed neglect or emotional abuse who had emotional, behavioral, and developmental features recorded or for whom the carer-child interaction was documented. Twenty-eight case-control (matched for socioeconomic, educational level, and ethnicity), 1 cross-sectional, and 13 cohort studies were included. Key features in the child included the following: aggression (11 studies) exhibited as angry, disruptive behavior, conduct problems, oppositional behavior, and low ego control; withdrawal or passivity (12 studies), including negative self-esteem, anxious or avoidant behavior, poor emotional knowledge, and difficulties in interpreting emotional expressions in others; developmental delay (17 studies), particularly delayed language, cognitive function, and overall development quotient; poor peer interaction (5 studies), showing poor social interactions, unlikely to act to relieve distress in others; and transition (6 studies) from ambivalent to avoidant insecure attachment pattern and from passive to increasingly aggressive behavior and negative self-representation. Emotional knowledge, cognitive function, and language deteriorate without intervention. Poor sensitivity, hostility, criticism, or disinterest characterize maternal-child interactions. Preschool children who have been neglected or emotionally abused exhibit a range of serious emotional and behavioral difficulties and adverse

Expression of Immunoglobulin Receptors with Distinctive Features Indicating Antigen Selection by Marginal Zone B Cells from Human Spleen

PubMed Central

Colombo, Monica; Cutrona, Giovanna; Reverberi, Daniele; Bruno, Silvia; Ghiotto, Fabio; Tenca, Claudya; Stamatopoulos, Kostas; Hadzidimitriou, Anastasia; Ceccarelli, Jenny; Salvi, Sandra; Boccardo, Simona; Calevo, Maria Grazia; De Santanna, Amleto; Truini, Mauro; Fais, Franco; Ferrarini, Manlio

2013-01-01

Marginal zone (MZ) B cells, identified as surface (s)IgMhighsIgDlowCD23low/−CD21+CD38− B cells, were purified from human spleens, and the features of their V(D)J gene rearrangements were investigated and compared with those of germinal center (GC), follicular mantle (FM) and switched memory (SM) B cells. Most MZ B cells were CD27+ and exhibited somatic hypermutations (SHM), although to a lower extent than SM B cells. Moreover, among MZ B-cell rearrangements, recurrent sequences were observed, some of which displayed intraclonal diversification. The same diversifying sequences were detected in very low numbers in GC and FM B cells and only when a highly sensitive, gene-specific polymerase chain reaction was used. This result indicates that MZ B cells could expand and diversify in situ and also suggested the presence of a number of activation-induced cytidine deaminase (AID)-expressing B cells in the MZ. The notion of antigen-driven expansion/selection in situ is further supported by the VH CDR3 features of MZ B cells with highly conserved amino acids at specific positions and by the finding of shared (“stereotyped”) sequences in two different spleens. Collectively, the data are consistent with the notion that MZ B cells are a special subset selected by in situ antigenic stimuli. PMID:23877718

A hybrid feature selection and health indicator construction scheme for delay-time-based degradation modelling of rolling element bearings

NASA Astrophysics Data System (ADS)

Zhang, Bin; Deng, Congying; Zhang, Yi

2018-03-01

Rolling element bearings are mechanical components used frequently in most rotating machinery and they are also vulnerable links representing the main source of failures in such systems. Thus, health condition monitoring and fault diagnosis of rolling element bearings have long been studied to improve operational reliability and maintenance efficiency of rotatory machines. Over the past decade, prognosis that enables forewarning of failure and estimation of residual life attracted increasing attention. To accurately and efficiently predict failure of the rolling element bearing, the degradation requires to be well represented and modelled. For this purpose, degradation of the rolling element bearing is analysed with the delay-time-based model in this paper. Also, a hybrid feature selection and health indicator construction scheme is proposed for extraction of the bearing health relevant information from condition monitoring sensor data. Effectiveness of the presented approach is validated through case studies on rolling element bearing run-to-failure experiments.

The UV-visible absorption and fluorescence spectroscopy indicators for monitoring the evolution of green waste composts.

NASA Astrophysics Data System (ADS)

Mounier, Stéphane; Abaker, Madi; Domeizel, Mariane; Rapetti, Nicola

2014-05-01

The maturity process of compost goes through several phases that have to be monitored in order to optimize the production process which in turn assure a good quality product and less time consumption. In order to estimate rapidly the phase where the compost is present and to measure the cellulose, the ratio C:N and the Stability Index Organic Matter (ISMO) a crucial parameter that needs to be monitored and controlled is the temperature. However, the temperature is not really a good indicator for the maturity of the compost because it is not constant and it depends on the mixing and environmental processes. The final measurements are performed at the end of the production process after certain time period that is subjectively determined by the producer. The work presented here is based on the optical properties of the organic matter that are observed each month for a period of six months. The organic matter of 5 composts was extracted by water and analyzed by UV-VIS spectroscopic technique [1] and 3D fluorescence emission technique [2]. The usual indexes were calculated (E2/E3, E4/E6, EBZ/EET, SUVA254), but also the PARAFAC decomposition of the 3D fluorescence response by Milori [3] and the Hx indexes [4]. The comparison of these results and the cellulose composition with the corresponding ISMO index indicates that the maturity process occurs more rapidly then the expectation of the producers. Further, the combination of the indicators gives useful information about different processes that take place during the maturity of the compost such as aromatization, the condensation and the stabilization of the parameters.

FTIR absorption indices for thermal maturity in comparison with vitrinite reflectance R0 in type-II kerogens from Devonian black shales

USGS Publications Warehouse

Lis, G.P.; Mastalerz, Maria; Schimmelmann, A.; Lewan, M.D.; Stankiewicz, B.A.

2005-01-01

FTIR absorbance signals in kerogens and macerals were evaluated as indices for thermal maturity. Two sets of naturally matured type-II kerogens from the New Albany Shale (Illinois Basin) and the Exshaw Formation (Western Canada Sedimentary Basin) and kerogens from hydrous pyrolysis artificial maturation of the New Albany Shale were characterized by FTIR. Good correlation was observed between the aromatic/aliphatic absorption ratio and vitrinite reflectance R 0. FTIR parameters are especially valuable for determining the degree of maturity of marine source rocks lacking vitrinite. With increasing maturity, FTIR spectra express four trends: (i) an increase in the absorption of aromatic bands, (ii) a decrease in the absorption of aliphatic bands, (iii) a loss of oxygenated groups (carbonyl and carboxyl), and (iv) an initial decrease in the CH2/CH3 ratio that is not apparent at higher maturity in naturally matured samples, but is observed throughout increasing R0 in artificially matured samples. The difference in the CH2/CH 3 ratio in samples from natural and artificial maturation at higher maturity indicates that short-term artificial maturation at high temperatures is not fully equivalent to slow geologic maturation at lower temperatures. With increasing R0, the (carboxyl + carbonyl)/aromatic carbon ratio generally decreases, except that kerogens from the Exshaw Formation and from hydrous pyrolysis experiments express an intermittent slight increase at medium maturity. FTIR-derived aromaticities correlate well with R0, although some uncertainty is due to the dependence of FTIR parameters on the maceral composition of kerogen whereas R0 is solely dependent on vitrinite. ?? 2005 Elsevier Ltd. All rights reserved.

Prediction of BOD, COD, and total nitrogen concentrations in a typical urban river using a fluorescence excitation-emission matrix with PARAFAC and UV absorption indices.

PubMed

Hur, Jin; Cho, Jinwoo

2012-01-01

The development of a real-time monitoring tool for the estimation of water quality is essential for efficient management of river pollution in urban areas. The Gap River in Korea is a typical urban river, which is affected by the effluent of a wastewater treatment plant (WWTP) and various anthropogenic activities. In this study, fluorescence excitation-emission matrices (EEM) with parallel factor analysis (PARAFAC) and UV absorption values at 220 nm and 254 nm were applied to evaluate the estimation capabilities for biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total nitrogen (TN) concentrations of the river samples. Three components were successfully identified by the PARAFAC modeling from the fluorescence EEM data, in which each fluorophore group represents microbial humic-like (C1), terrestrial humic-like organic substances (C2), and protein-like organic substances (C3), and UV absorption indices (UV(220) and UV(254)), and the score values of the three PARAFAC components were selected as the estimation parameters for the nitrogen and the organic pollution of the river samples. Among the selected indices, UV(220), C3 and C1 exhibited the highest correlation coefficients with BOD, COD, and TN concentrations, respectively. Multiple regression analysis using UV(220) and C3 demonstrated the enhancement of the prediction capability for TN.

Synthesis temperature effect on the structural features and optical absorption of Zn(1-x)Co(x)Al2O4 oxides.

PubMed

Gaudon, M; Apheceixborde, A; Ménétrier, M; Le Nestour, A; Demourgues, A

2009-10-05

Zinc/cobalt aluminates with spinel-type structure were prepared by a polymeric route, leading to a pure phase with controlled grain size. The prepared pigments were characterized by powder X-ray diffraction Rietveld analyses in order to determine structural features, scanning electron microscopy for morphological investigation, helium pycnometry and (27)Al MAS NMR in order to highlight the occurrence of defects inside the structure, and UV-visible-near-IR spectroscopy to identify electronic transitions responsible for the compounds' color. The green-blue coloration of these pigments is known to be dependent on the sample thermal history. Here, for the first time, the Zn(1-x)Co(x)Al(2)O(4) color is newly interpreted. The pigment is green once synthesized at low temperature (i.e., with diminution of the pigment grain size); this variation was attributed to the appearance of a new absorption band located at about 500 nm, linked to a complex network feature involving Co ions in octahedral sites as well as oxygen and cationic vacancies. Hence, this work shows the possibility of easily getting a nonstoichiometric network with an abnormal cationic distribution from "chimie douce" processes with moderate synthesis temperature, and so various colorations for the same composition.

Magnetic Resonance Imaging in Psoriatic Arthritis: A Descriptive Study of Indications, Features and Effect on Treatment Change.

PubMed

Maldonado-Ficco, Hernán; Sheane, Barry J; Thavaneswaran, Arane; Chandran, Vinod; Gladman, Dafna D

2017-08-01

The aims of this study were to describe the indications for, and features of, axial/peripheral joint magnetic resonance imaging (MRI) in psoriatic arthritis (PsA) and to examine the influence of MRI findings on clinical practice. All axial and peripheral (hand and/or foot) MRI scans on patients attending the Toronto PsA clinic l between 2003 and 2014 were included. Scan details were garnered from the radiologist's official report. A chart review was performed to determine if MRI findings contributed to a change of treatment. One hundred sixty-eight scans were performed on 125 patients (135 axial and 33 peripheral). The mean age was 50.5 (SD, 11.5) years, with 51.2% being female. Mean duration of PsA was 11.2 (SD, 10.9) years. Of the axial scans, the majority were performed on the whole spine (excluding the sacrum) (27.4%) or the sacroiliac joints and spine together (45.2%). The predominant indications were for suspected inflammatory (51.1%) or degenerative (24.4%) disease. Magnetic resonance imaging revealed inflammatory and/or structural change in 34.1% versus 54.8% with degenerative changes. In MRI axial inflammation (n = 25), the majority (48%) had sacroiliac joint involvement, whereas 28% had inflammation at 2 or more sites.Of the periphery, 60.6% of scans were on hands and 21.2% were on feet alone. The main indications were for suspected subclinical synovitis (78.8%). Inflammatory arthritis was the MRI diagnosis in 72.7%. Magnetic resonance imaging findings influenced treatment change (n = 32) in 56.3%, but were insufficient to effect treatment change without clinical findings (100%). Magnetic resonance imaging is useful in evaluating patients with active PsA, particularly when suspecting inflammation and radiographic findings are unhelpful. In some cases, it can be used as an adjunct to clinical examination in determining treatment change.

Evaluating the Nature of So-Called S*-State Feature in Transient Absorption of Carotenoids in Light-Harvesting Complex 2 (LH2) from Purple Photosynthetic Bacteria.

PubMed

Niedzwiedzki, Dariusz M; Hunter, C Neil; Blankenship, Robert E

2016-11-03

Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S* state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation-bacteriochlorophyll anion pair. These findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes.

Evaluating the Nature of So-Called S*-State Feature in Transient Absorption of Carotenoids in Light-Harvesting Complex 2 (LH2) from Purple Photosynthetic Bacteria

PubMed Central

2016-01-01

Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S* state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation–bacteriochlorophyll anion pair. These findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes. PMID:27726397

Evaluating the nature of so-called S*-State feature in transient absorption of carotenoids in light-harvesting complex 2 (LH2) from purple photosynthetic bacteria

DOE PAGES

Niedzwiedzki, Dariusz M.; Hunter, C. Neil; Blankenship, Robert E.

2016-10-11

Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S*more » state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation- bacteriochlorophyll anion pair. Lastly, these findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes.« less

Evaluating the nature of so-called S*-State feature in transient absorption of carotenoids in light-harvesting complex 2 (LH2) from purple photosynthetic bacteria

SciTech Connect

Niedzwiedzki, Dariusz M.; Hunter, C. Neil; Blankenship, Robert E.

Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S*more » state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation- bacteriochlorophyll anion pair. Lastly, these findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes.« less

Uterine malignant mixed Müllerian tumor (Metaplasic carcinoma) in the cat: clinicopathologic features and proliferation indices.

PubMed

Nicòtina, P A; Zanghì, A; Catone, G

2002-01-01

A homologous malignant mixed Müllerian tumor of the uterus occurring in an 8-year-old Persian cat was described with regard to its clinical and pathologic features. A polypoid multinodular mass of the right uterine horn was shown by an ultrasound examination. Grossly, the right uterine horn was enlarged because of a vegetative and infiltrating tumor, grayish-white in color, that penetrated the uterine wall to the level of the perimetrium. Many metastatic nodules were found in abdominal and thoracic cavities. Histologically, the neoplasm had both carcinomatous and sarcomatous components and was diagnosed as an uterine malignant mixed Müllerian tumor. This is the fourth case reported in cats. The histologic features and proliferation rate of this tumor were similar to the corresponding human neoplasms, which occur mainly in postmenopausal women. The possible hormone dependence of the tumor is briefly discussed.

Asymmetric dimethylarginine association with antioxidants intake in healthy young adults: a role as an indicator of metabolic syndrome features.

PubMed

Puchau, Blanca; Zulet, María A; Urtiaga, Goizane; Navarro-Blasco, Iñigo; Martínez, J Alfredo

2009-10-01

The purpose of this study was to evaluate the potential associations between serum asymmetric dimethylarginine (ADMA) and several anthropometric, biochemical, and lifestyle features in healthy young adults, emphasizing on the putative effects of the antioxidant intake on ADMA concentrations. Anthropometric and blood pressure measurements as well as lifestyle features and antioxidant intake were analyzed in 93 healthy young adults aged 18 to 34 years. Fasting blood samples were collected for the measurement of glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triacylglycerols, and ADMA concentrations, as well as erythrocyte glutathione peroxidase activity. Nail samples were collected for the analysis of selenium and zinc concentrations. Values of body mass index (P = .004), waist circumference (P = .008), waist-to-height ratio (P = .046), systolic blood pressure (P < .001), serum glucose (P < .001), and nail selenium (P = .004) and zinc (P = .018) were significantly different between subjects with serum ADMA higher and lower than the median (cutoff, 458 nmol/L). Furthermore, ADMA showed a positive association with several adiposity markers such as body weight (P < .001), body mass index (P < .001), waist circumference (P = .006), waist-to-height ratio (P = .020), body fat mass (P = .001), systolic blood pressure (P = .001), and serum glucose (P < .001), whereas erythrocyte glutathione peroxidase activity (P = .021) and nail selenium (P = .040) and zinc values (P = .013) were statistically significant negative predictors of ADMA concentrations. In conclusion, ADMA seems to be related with selenium and zinc status and several anthropometric and biochemical measurements linked to metabolic syndrome in apparently healthy young adults. These findings support a role for antioxidant/trace element intake in the modulation of ADMA, whose assessment may be a marker of metabolic syndrome manifestations.

Scale invariant feature transform in adaptive radiation therapy: a tool for deformable image registration assessment and re-planning indication

NASA Astrophysics Data System (ADS)

Paganelli, Chiara; Peroni, Marta; Riboldi, Marco; Sharp, Gregory C.; Ciardo, Delia; Alterio, Daniela; Orecchia, Roberto; Baroni, Guido

2013-01-01

Adaptive radiation therapy (ART) aims at compensating for anatomic and pathological changes to improve delivery along a treatment fraction sequence. Current ART protocols require time-consuming manual updating of all volumes of interest on the images acquired during treatment. Deformable image registration (DIR) and contour propagation stand as a state of the ART method to automate the process, but the lack of DIR quality control methods hinder an introduction into clinical practice. We investigated the scale invariant feature transform (SIFT) method as a quantitative automated tool (1) for DIR evaluation and (2) for re-planning decision-making in the framework of ART treatments. As a preliminary test, SIFT invariance properties at shape-preserving and deformable transformations were studied on a computational phantom, granting residual matching errors below the voxel dimension. Then a clinical dataset composed of 19 head and neck ART patients was used to quantify the performance in ART treatments. For the goal (1) results demonstrated SIFT potential as an operator-independent DIR quality assessment metric. We measured DIR group systematic residual errors up to 0.66 mm against 1.35 mm provided by rigid registration. The group systematic errors of both bony and all other structures were also analyzed, attesting the presence of anatomical deformations. The correct automated identification of 18 patients who might benefit from ART out of the total 22 cases using SIFT demonstrated its capabilities toward goal (2) achievement.

Aberrant proteins featured in the saliva of habitual betel quid chewers: an indication of early oral premalignancy?

PubMed

Jessie, Kala; Jayapalan, Jaime Jacqueline; Rahim, Zubaidah Haji Abdul; Hashim, Onn Haji

2014-12-01

Prolonged chewing of betel quid is known to cause oral diseases, including cancer. The present study was performed to screen for aberrant proteins in the saliva of habitual betel quid chewers compared to nonchewers. Saliva of female subjects (n = 10) who had been chewing betel quid for more than 20 years and nonbetel quid chewers (n = 10) of the same gender and range of age was analyzed by gel-based proteomics. Increased structural microheterogeneity of saliva haptoglobin beta chains indicated by shifts of focused spots similar to that earlier reported in patients with oral squamous cell carcinoma, and their relatively higher abundance compared to nonbetel quid chewers, were detected in saliva protein profiles of all chewers. In addition, the majority of the betel quid chewers also showed significant higher abundance of hemopexin, alpha-1B glycoprotein, alpha1-antitrypsin, complement C3, and transthyretin. These proteins had previously been associated with several different cancers. Our data demonstrated different forms of protein aberration in the saliva of betel quid chewers, which may be indicative of early oral precancerous conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Late Pleistocene eolian features in southeastern Maryland and Chesapeake Bay region indicate strong WNW-NW winds accompanied growth of the Laurentide Ice Sheet

USGS Publications Warehouse

Markewich, H.W.; Litwin, R.J.; Pavich, M.J.; Brook, G.A.

2009-01-01

Inactive parabolic dunes are present in southeastern Maryland, USA, along the east bank of the Potomac River. More elongate and finer-grained eolian deposits and paha-like ridges characterize the Potomac River-Patuxent River upland and the west side of Chesapeake Bay. These ridges are streamlined erosional features, veneered with eolian sediment and interspersed with dunes in the low-relief headwaters of Potomac- and Patuxent-river tributaries. Axis data for the dunes and ridges indicate formation by WNW-NW winds. Optically stimulated luminescence and radiocarbon age data suggest dune formation from ??? 33-15??ka, agreeing with the 30-13??ka ages Denny, C.S., Owens, J.P., Sirkin, L., Rubin, M., 1979. The Parsonburg Sand in the central Delmarva Peninsula, Maryland and Delaware. U.S. Geol. Surv. Prof. Pap. 1067-B, 16??pp. suggested for eolian deposits east of Chesapeake Bay. Age range and paleowind direction(s) for eolian features in the Bay region approximate those for late Wisconsin loess in the North American midcontinent. Formation of midcontinent loess and Bay-region eolian features was coeval with rapid growth of the Laurentide Ice Sheet and strong cooling episodes (??18O minima) evident in Greenland ice cores. Age and paleowind-direction coincidence, for eolian features in the midcontinent and Bay region, indicates strong mid-latitude WNW-NW winds for several hundred kilometers south of the Laurentide glacial terminus that were oblique to previously simulated anticyclonic winds for the last glacial maximum.

Molecular Indicators of Stress-Induced Neuroinflammation in a Mouse Model Simulating Features of Post-Traumatic Stress Disorder (Open Access)

DTIC Science & Technology

2017-05-23

OPEN ORIGINAL ARTICLE Molecular indicators of stress-induced neuroinflammation in a mouse model simulating features of post -traumatic stress disorder... post -traumatic stress disorder (PTSD). The model involved exposure of an intruder (male C57BL/6) mouse to a resident aggressor (male SJL) mouse for 5...revealed that neurogenesis and synaptic plasticity pathways were activated during the early responses but were inhibited after the later post -trauma

Investigation of the multiplet features of SrTiO 3 in X-ray absorption spectra based on configuration interaction calculations

DOE PAGES

Wu, M.; Xin, Houlin L.; Wang, J. O.; ...

2018-04-24

Synchrotron-based L 2,3-edge absorption spectra show strong sensitivities to the local electronic structure and chemical environment. However, detailed physical information cannot be extracted easily without computational aids. Here in this study using the experimental Ti L 2,3-edges absorption spectrum of SrTiO 3as a fingerprint and considering full multiplet effects, calculations yield different energy parameters characterizing local ground state properties. The peak splitting and intensity ratios of the L 3 and L 2 set of peaks are carefully analyzed quantitatively, giving rise to a small hybridization energy around 1.2 eV, and the different hybridization energy values reported in the literature aremore » further addressed. Finally, absorption spectra with different linearly polarized photons under various tetragonal crystal fields are investigated, revealing a non-linear orbital–lattice interaction, and a theoretical guidance for material engineering of SrTiO 3-based thin films and heterostructures is offered. Finally, detailed analysis of spectrum shifts with different tetragonal crystal fields suggests that the e g crystal field splitting is a necessary parameter for a thorough analysis of the spectra, even though it is not relevant for the ground state properties.« less

Investigation of the multiplet features of SrTiO 3 in X-ray absorption spectra based on configuration interaction calculations

SciTech Connect

Wu, M.; Xin, Houlin L.; Wang, J. O.

Synchrotron-based L 2,3-edge absorption spectra show strong sensitivities to the local electronic structure and chemical environment. However, detailed physical information cannot be extracted easily without computational aids. Here in this study using the experimental Ti L 2,3-edges absorption spectrum of SrTiO 3as a fingerprint and considering full multiplet effects, calculations yield different energy parameters characterizing local ground state properties. The peak splitting and intensity ratios of the L 3 and L 2 set of peaks are carefully analyzed quantitatively, giving rise to a small hybridization energy around 1.2 eV, and the different hybridization energy values reported in the literature aremore » further addressed. Finally, absorption spectra with different linearly polarized photons under various tetragonal crystal fields are investigated, revealing a non-linear orbital–lattice interaction, and a theoretical guidance for material engineering of SrTiO 3-based thin films and heterostructures is offered. Finally, detailed analysis of spectrum shifts with different tetragonal crystal fields suggests that the e g crystal field splitting is a necessary parameter for a thorough analysis of the spectra, even though it is not relevant for the ground state properties.« less

Using High Resolution Commercial Satellite Imagery to Quantify Spatial Features of Urban Areas and their Relationship to Quality of Life Indicators in Accra, Ghana

NASA Astrophysics Data System (ADS)

Sandborn, A.; Engstrom, R.; Yu, Q.

2014-12-01

Mapping urban areas via satellite imagery is an important task for detecting and anticipating land cover and land use change at multiple scales. As developing countries experience substantial urban growth and expansion, remotely sensed based estimates of population and quality of life indicators can provide timely and spatially explicit information to researchers and planners working to determine how cities are changing. In this study, we use commercial high spatial resolution satellite imagery in combination with fine resolution census data to determine the ability of using remotely sensed data to reveal the spatial patterns of quality of life in Accra, Ghana. Traditionally, spectral characteristics are used on a per-pixel basis to determine land cover; however, in this study, we test a new methodology that quantifies spatial characteristics using a variety of spatial features observed in the imagery to determine the properties of an urban area. The spatial characteristics used in this study include histograms of oriented gradients, PanTex, Fourier transform, and line support regions. These spatial features focus on extracting structural and textural patterns of built-up areas, such as homogeneous building orientations and straight line indices. Information derived from aggregating the descriptive statistics of the spatial features at both the fine-resolution census unit and the larger neighborhood level are then compared to census derived quality of life indicators including information about housing, education, and population estimates. Preliminary results indicate that there are correlations between straight line indices and census data including available electricity and literacy rates. Results from this study will be used to determine if this methodology provides a new and improved way to measure a city structure in developing cities and differentiate between residential and commercial land use zones, as well as formal versus informal housing areas.

A randomised cross-over trial in healthy adults indicating improved absorption of omega-3 fatty acids by pre-emulsification

PubMed Central

Garaiova, Iveta; Guschina, Irina A; Plummer, Sue F; Tang, James; Wang, Duolao; Plummer, Nigel T

2007-01-01

Background The health benefits of increased intakes of omega-3 fatty acids are well established but palatability often presents a problem. The process of emulsification is used in the food industry to provide a wider spectrum of use, often with the result of increased consumption. Moreover, as emulsification is an important step in the digestion and absorption of fats, the pre-emulsification process may enhance digestion and absorption. In this study the levels of plasma fatty acid and triacylglycerol (TAG) following the ingestion of either an oil mixture or an emulsified oil mixture have been compared. Methods In this randomised cross-over study, 13 volunteers received the oil mixture and 11 received the oil emulsion as part of an otherwise fat free meal. Blood samples were collected at 0, 1.5, 3, 4.5, 6, 7.5 and 9 hours after ingestion of oil, separated and stored at -20°C. Plasma triacylglycerols were assessed spectrophotometrically and fatty acids were determined by gas chromatography. Following a washout period of twenty days the procedure was repeated with the assignments reversed. Results The postprandial plasma TAG and the C18:3 (n-6), C18:3(n-3), C20:5(n-3) and C22:6 (n-3) polyunsaturated fatty acid (PUFA) levels for the emulsified oil group were increased significantly (P = 0.0182; P = 0.0493; P = 0.0137; P < 0.0001; P = 0.0355 respectively) compared with the non-emulsified oil group. The C16:0 and C18:0 saturated fatty acids, the C18:1 (n-9) monounsaturated fatty acid and the C18:2 PUFA were not significantly different for the oil and emulsified oil groups. Conclusion Pre-emulsification of an oil mixture prior to ingestion increases the absorption of longer chain more highly unsaturated fatty acids (especially eicosapentaenoic acid and docosahexaenoic acid) but does not affect absorption of shorter chain less saturated fatty acids, suggesting that pre-emulsification of fish oils may be a useful means of boosting absorption of these beneficial fatty

Detailed Spectral Analysis of the 260 ks XMM-Newton Data of 1E 1207.4-5209 and Significance of a 2.1 keV Absorption Feature

NASA Astrophysics Data System (ADS)

Mori, Kaya; Chonko, James C.; Hailey, Charles J.

2005-10-01

We have reanalyzed the 260 ks XMM-Newton observation of 1E 1207.4-5209. There are several significant improvements over previous work. First, a much broader range of physically plausible spectral models was used. Second, we have used a more rigorous statistical analysis. The standard F-distribution was not employed, but rather the exact finite statistics F-distribution was determined by Monte Carlo simulations. This approach was motivated by the recent work of Protassov and coworkers and Freeman and coworkers. They demonstrated that the standard F-distribution is not even asymptotically correct when applied to assess the significance of additional absorption features in a spectrum. With our improved analysis we do not find a third and fourth spectral feature in 1E 1207.4-5209 but only the two broad absorption features previously reported. Two additional statistical tests, one line model dependent and the other line model independent, confirmed our modified F-test analysis. For all physically plausible continuum models in which the weak residuals are strong enough to fit, the residuals occur at the instrument Au M edge. As a sanity check we confirmed that the residuals are consistent in strength and position with the instrument Au M residuals observed in 3C 273.

Late Pleistocene eolian features in southeastern Maryland and Chesapeake Bay region indicate strong WNW-NW winds accompanied growth of the Laurentide Ice Sheet

NASA Astrophysics Data System (ADS)

Markewich, Helaine W.; Litwin, Ronald J.; Pavich, Milan J.; Brook, George A.

2009-05-01

Inactive parabolic dunes are present in southeastern Maryland, USA, along the east bank of the Potomac River. More elongate and finer-grained eolian deposits and paha-like ridges characterize the Potomac River-Patuxent River upland and the west side of Chesapeake Bay. These ridges are streamlined erosional features, veneered with eolian sediment and interspersed with dunes in the low-relief headwaters of Potomac- and Patuxent-river tributaries. Axis data for the dunes and ridges indicate formation by WNW-NW winds. Optically stimulated luminescence and radiocarbon age data suggest dune formation from ˜ 33-15 ka, agreeing with the 30-13 ka ages Denny, C.S., Owens, J.P., Sirkin, L., Rubin, M., 1979. The Parsonburg Sand in the central Delmarva Peninsula, Maryland and Delaware. U.S. Geol. Surv. Prof. Pap. 1067-B, 16 pp. suggested for eolian deposits east of Chesapeake Bay. Age range and paleowind direction(s) for eolian features in the Bay region approximate those for late Wisconsin loess in the North American midcontinent. Formation of midcontinent loess and Bay-region eolian features was coeval with rapid growth of the Laurentide Ice Sheet and strong cooling episodes (δ 18O minima) evident in Greenland ice cores. Age and paleowind-direction coincidence, for eolian features in the midcontinent and Bay region, indicates strong mid-latitude WNW-NW winds for several hundred kilometers south of the Laurentide glacial terminus that were oblique to previously simulated anticyclonic winds for the last glacial maximum.

The spacing of the interstellar 6.2 and 7.7 micron emission features as an indicator of polycyclic aromatic hydrocarbon size

NASA Technical Reports Server (NTRS)

Hudgins, D. M.; Allamandola, L. J.

1999-01-01

A database of astrophysically relevant, infrared spectral measurements on a wide variety of neutral as well as positively and negatively charged polycyclic aromatic hydrocarbons (PAHs), ranging in size from C10H8 through C48H20, is now available to extend the interstellar PAH model. Beyond simply indicating general characteristics of the carriers, this collection of data now makes it possible to conduct a more thorough interpretation of the details of the interstellar spectra and thereby derive deeper insights into the nature of the emitting material and conditions in the emission zones. This Letter is the first such implementation of this spectral database. The infrared spectra of PAH cations, the main PAH form in the most energetic emission zones, are usually dominated by a few strong features in the 1650-1100 cm-1 (6.1-9.1 microns) region that tend to cluster the vicinity of the interstellar emission bands at 1610 and 1320 cm-1 (6.2 and 7.6 microns), but with spacings typically somewhat less than that observed in the canonical interstellar spectrum. However, the spectra in the database show that this spacing increases steadily with molecular size. Extrapolation of this trend indicates that PAHs in the 50-80 carbon atom size range are entirely consistent with the observed interstellar spacing. Furthermore, the profile of the 1610 cm-1 (6.2 microns) interstellar band indicates that PAHs containing as few as 20 carbon atoms contribute to this feature.

The Spacing of the Interstellar 6.2 Microns and 7.7 Microns Emission Features as an Indicator of PAH Size

NASA Technical Reports Server (NTRS)

Hudgins, Douglas M.; Allamandola, L. J.; Mead, Susan (Technical Monitor)

1998-01-01

A database of astrophysically relevant, infrared spectral measurements on a wide variety of neutral as well as positively and negatively charged polycyclic aromatic hydrocarbons ranging in size from C10H8 through C48H20 is now available to extend the interstellar PAH model. Beyond simply indicating general characteristics of the carriers, this collection of data now makes it possible to conduct a more thorough interpretation of the details of the interstellar spectra and thereby derive deeper insights into the nature of the emitting material and conditions in the emission zones. This paper is the first such implementation of this spectral database. The infrared spectra of PAH cations, the main PAH form in the most energetic emission zones, are usually dominated by a few strong features in the 1650 - 1100 per centimeter (6.1 - 9.1 microns) region which tend to cluster in the vicinity of the interstellar emission bands at 1610 per centimeter and 1320 per centimeter (6.2 and 7.6 microns) but with spacings typically somewhat less than that observed in the canonical interstellar spectrum. However, the spectra in the database show that this spacing increases steadily with molecular size. Extrapolation of this trend indicates that PAHS in the 50 to 80 carbon atom size range are entirely consistent with the observed interstellar spacing. Furthermore, the profile of the 1610 per centimeter (6.2 microns) interstellar band indicates that PAHS containing as few as 20 carbon atoms contribute to this feature.

Variation of the 3-μm absorption feature on Mars: observations over eastern Valles Marineris by the mariner 6 infrared spectrometer

USGS Publications Warehouse

Calvin, Wendy M.

1997-01-01

A new approach for calibration of the shortest wavelength channel (1.8 to 6.0 μm) of the Mariner 6 infrared spectrometer was derived. This calibration provides a new description of the instrument response function from 1.8 to 3.7 μm and accounts for the thermal contribution to the signal at longer wavelengths. This allows the two segments from 1.8 to 6 μm to be merged into a single spectrum. The broad water of hydration absorption spans these two segments and is examined in these merged spectra using a method of band integration. Unlike previous analyses which rely on ratios at two wavelengths, the integration method can assess the band strength independently from the albedo in the near infrared. Spectra taken over the eastern end of the Valles Marineris are examined for variations of the band-integrated value, and three distinct clusters are found. Within the estimated uncertainty, two clusters (both low and high albedo) have approximately the same integrated band depth. The third cluster (medium albedo) has an integrated band depth about 10% higher. This difference cannot be systematically attributed to either surface or atmospheric parameters and suggests variation in the amount of water either chemically or physically bound in surface materials. Approximately one-half of the high integrated band depth cluster is associated with chaotic terrain at the source of outflow channels, the other half occurs over lower inertia plains adjacent to chasmata. This suggests both surface physical properties and mineralogy as well as water in exchange with the atmosphere contribute to the 3-μm bound water absorption.

ABSORPTION ANALYZER

DOEpatents

Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

1961-11-14

A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

Self-organizing feature map (neural networks) as a tool to select the best indicator of road traffic pollution (soil, leaves or bark of Robinia pseudoacacia L.).

PubMed

Samecka-Cymerman, A; Stankiewicz, A; Kolon, K; Kempers, A J

2009-07-01

Concentrations of the elements Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were measured in the leaves and bark of Robinia pseudoacacia and the soil in which it grew, in the town of Oleśnica (SW Poland) and at a control site. We selected this town because emission from motor vehicles is practically the only source of air pollution, and it seemed interesting to evaluate its influence on soil and plants. The self-organizing feature map (SOFM) yielded distinct groups of soils and R. pseudoacacia leaves and bark, depending on traffic intensity. Only the map classifying bark samples identified an additional group of highly polluted sites along the main highway from Wrocław to Warszawa. The bark of R. pseudoacacia seems to be a better bioindicator of long-term cumulative traffic pollution in the investigated area, while leaves are good indicators of short-term seasonal accumulation trends.

Neuro-fuzzy inference system Prediction of stability indices and Sodium absorption ratio in Lordegan rural drinking water resources in west Iran.

PubMed

Takdastan, Afshin; Mirzabeygi Radfard, Majid; Yousefi, Mahmood; Abbasnia, Abbas; Khodadadia, Rouhollah; Soleimani, Hamed; Mahvi, Amir Hossein; Naghan, Davood Jalili

2018-06-01

According to World Health Organization guidelines, corrosion control is an important aspect of safe drinking-water supplies. Water always includes ingredients, dissolved gases and suspended materials. Although some of these water ingredients is indispensable for human beings, these elements more than permissible limits, could be endanger human health. The aim of this study is to assess physical and chemical parameters of drinking water in the rural areas of Lordegan city, also to determine corrosion indices. This cross-sectional study has carried out with 141 taken samples during 2017 with 13 parameters, which has been analyzed based on standard method and to estimate the water quality indices from groundwater using ANFIS. Also with regard to standard conditions, results of this paper are compared with Environmental Protection Agency and Iran national standards. Five indices, Ryznar Stability Index (RSI), Langlier Saturation Index (LSI), Larson-Skold Index (LS), Puckorius Scaling Index (PSI), and Aggressive Index (AI) programmed by using Microsoft Excel software. Owing to its simplicity, the program, can easily be used by researchers and operators. Parameters included Sulfate, Sodium, Chloride, and Electrical Conductivity respectively were 13.5, 28, 10.5, and 15% more than standard level. The amount of Nitrate, in 98% of cases were in permissible limits and about 2% were more than standard level. Result of presented research indicate that water is corrosive at 10.6%,89.4%,87.2%,59.6% and 14.9% of drinking water supply reservoirs, according to LSI, RSI, PSI, LS and AI, respectively.

Studies on the nature of the primary reactions of photosystem II in photosynthesis. I. The electrochromic 515 nm absorption change as an appropriate indicator for the functional state of the photochemical active centers of system II in DCMY poisoned chloroplasts.

PubMed

Renger, G; Wolff, C

1975-01-01

The field indicating electrochromic 515 nm absorption change has been measured under different excitation conditions in DCMU poisoned chloroplasts in the presence of benzylviologen as electron acceptor. It has been found: 1. The amplitude of the 515 nm absorption change is nearly completely suppressed under repetitive single turnover flash excitation conditions which kinetically block the back reaction around system II (P. Bennoun, Biochim. Biophys. Acta 216, 357 [1970]). 2. The amplitude of the 515 nm absorption change measured under repetitive single turnover flash excitation conditions which allow the completion of the back reaction during the dark time between the flashes (measuring light beam switched off) amounts in the presence of 2 mum DCMU nearly 50% of the electrochromic 515 nm amplitude obtained in the absence of DCMU. In DCMU poisoned chloroplasts this amplitude is significantly decreased by hydroxylaminhydrochloride, but nearly doubled in the presence of CDIP+ascorbate. 3. The dependence of the 515 nm amplitude on the time td between the flashes kinetically resembles the back reaction around system ?II. The time course of the back reaction can be fairly described either by a second order reaction or by a two phase exponential kinetics. 4. 1,3-dinitrobenzene (DNE) or alpha-bromo-alpha-benzylmalodinitril (BBMD) reduce the 515 nm amplitude in DCMU poisoned chloroplasts, but seem to influecne only slightly the kinetics of the back reaction. 5. The dependence of the 515 nm amplitude on the flash light intensity (the amplitude normalized to 1 at 100% flash light intensity) is not changed by DNB. Based on these experimental data it has been concluded that in DCMU poisoned chloroplasts the amplitude of the 515 nm absorption change reflects the functional state of photosystem II centers (designated as photoelectric dipole generators II) under suitable excitation conditions. Furthermore, it is inferred that in DCMU poisoned chlorplasts the photoelectric dipole

Rapidly variable relatvistic absorption

NASA Astrophysics Data System (ADS)

Parker, M.; Pinto, C.; Fabian, A.; Lohfink, A.; Buisson, D.; Alston, W.; Jiang, J.

2017-10-01

I will present results from the 1.5Ms XMM-Newton observing campaign on the most X-ray variable AGN, IRAS 13224-3809. We find a series of nine absorption lines with a velocity of 0.24c from an ultra-fast outflow. For the first time, we are able to see extremely rapid variability of the UFO features, and can link this to the X-ray variability from the inner accretion disk. We find a clear flux dependence of the outflow features, suggesting that the wind is ionized by increasing X-ray emission.

Percutaneous absorption

PubMed Central

Brisson, Paul

1974-01-01

Clinical effectiveness of topically applied medications depends on the ability of the active ingredient to leave its vehicle and penetrate into the epidermis. The stratum corneum is that layer of the epidermis which functionally is the most important in limiting percutaneous absorption, showing the characteristics of a composite semipermeable membrane. A mathematical expression of transepidermal diffusion may be derived from Fick's Law of mass transport; factors altering the rate of diffusion are discussed. PMID:4597976

Constructing organic D-A-π-A-featured sensitizers with a quinoxaline unit for high-efficiency solar cells: the effect of an auxiliary acceptor on the absorption and the energy level alignment.

PubMed

Pei, Kai; Wu, Yongzhen; Wu, Wenjun; Zhang, Qiong; Chen, Baoqin; Tian, He; Zhu, Weihong

2012-06-25

Four organic D-A-π-A-featured sensitizers (TQ1, TQ2, IQ1, and IQ2) have been studied for high-efficiency dye-sensitized solar cells (DSSCs). We employed an indoline or a triphenylamine unit as the donor, cyanoacetic acid as the acceptor/anchor, and a thiophene moiety as the conjugation bridge. Additionally, an electron-withdrawing quinoxaline unit was incorporated between the donor and the π-conjugation unit. These sensitizers show an additional absorption band covering the broad visible range in solution. The contribution from the incorporated quinoxaline was investigated theoretically by using DFT and time-dependent DFT. The incorporated low-band-gap quinoxaline unit as an auxiliary acceptor has several merits, such as decreasing the band gap, optimizing the energy levels, and realizing a facile structural modification on several positions in the quinoxaline unit. As demonstrated, the observed additional absorption band is favorable to the photon-to-electron conversion because it corresponds to the efficient electron transitions to the LUMO orbital. Electrochemical impedance spectroscopy (EIS) Bode plots reveal that the replacement of a methoxy group with an octyloxy group can increase the injection electron lifetime by a factor of 2.4. IQ2 and TQ2 can perform well without any co-adsorbent, successfully suppress the charge recombination from TiO(2) conduction band to I(3)(-) in the electrolyte, and enhance the electron lifetime, resulting in a decreased dark current and enhanced open circuit voltage (V(oc)) values. By using a liquid electrolyte, DSSCs based on dye IQ2 exhibited a broad incident photon-to-current conversion efficiency (IPCE) action spectrum and high efficiency (η=8.50 %) with a short circuit current density (J(sc)) of 15.65 mA cm(-2), a V(oc) value of 776 mV, a fill factor (FF) of 0.70 under AM 1.5 illumination (100 mW cm(-2)). Moreover, the overall efficiency remained at 97% of the initial value after 1000 h of visible

Geological features indicative of processes related to the hematite formation in Meridiani Planum and Aram Chaos, Mars: a comparison with diagenetic hematite deposits in southern Utah, USA

NASA Astrophysics Data System (ADS)

Ormö, Jens; Komatsu, Goro; Chan, Marjorie A.; Beitler, Brenda; Parry, William T.

2004-10-01

In order to understand the formation of the few but large, hematite deposits on Mars, comparisons are often made with terrestrial hematite occurrences. In southern Utah, hematite concretions have formed within continental sandstones and are exposed as extensive weathered-out beds. The hematite deposits are linked to geological and geomorphological features such as knobs, buttes, bleached beds, fractures and rings. These terrestrial features are visible in aerial and satellite images, which enables a comparison with similar features occurring extensively in the martian hematite-rich areas. The combination of processes involved in the movement and precipitation of iron in southern Utah can provide new insights in the context of the hematite formation on Mars. Here we present a mapping of the analogue geological and geomorphological features in parts of Meridiani Planum and Aram Chaos. Based on mapping comparisons with the Utah occurrences, we present models for the formation of the martian analogues, as well as a model for iron transport and precipitation on Mars. Following the Utah model, high albedo layers and rings in the mapped area on Mars are due to removal or lack of iron, and precipitation of secondary diagenetic minerals as fluids moved up along fractures and permeable materials. Hematite was precipitated intraformationally where the fluid transporting the reduced iron met oxidizing conditions. Our study shows that certain geological/geomorphological features can be linked to the hematite formation on Mars and that pH differences could suffice for the transport of the iron from an orthopyroxene volcanoclastic source rock. The presence of organic compounds can enhance the iron mobilization and precipitation processes. Continued studies will focus on possible influence of biological activity and/or methane in the formation of the hematite concretions in Utah and on Mars.

The 5-day wave and ionospheric absorption

NASA Technical Reports Server (NTRS)

Fraser, G. J.

1977-01-01

In a previous paper, Fraser and Thorpe (1976) indicated that the average partial-coherence spectra for three summers and the average for three winters at a southern mid-latitude site had a dominant peak at a period of about six days. This peak in coherence between absorption and temperature is anomalous, and the present paper explains how some of the unexpected coherence features can be explained by the five-day wave described by Geisler and Dickinson (1976) and whose existence in the upper stratosphere was discussed by Rodgers (1976).

IUE's View of Callisto: Detection of an SO2 Absorption Correlated to Possible Torus Neutral Wind Alterations

NASA Technical Reports Server (NTRS)

Lane, Arthur L.; Domingue, Deborah L.

1997-01-01

Observations taken with the International Ultraviolet Explorer (IUE) detected a 0.28 micron absorption feature on Callisto's leading and Jupiter-facing hemispheres. This feature is similar to Europa's 0.28 micron feature, however it shows no correlation with magnetospheric ion bombardment. The strongest 0.28 micron signature is seen in the region containing the Valhalla impact. This absorption feature also shows some spatial correlation to possible neutral wind interactions, suggestive of S implantation (rather than S(sub x)) into Callisto's water ice surface, Indications of possible temporal variations (on the 10% level) are seen at other wavelengths between the 1984-1986 and the 1996 observations.

Surface Textures and Features Indicative of Endogenous Growth at the McCartys Flow Field, NM, as an Analog to Martian Volcanic Plains

NASA Technical Reports Server (NTRS)

Bleacher, Jacob E.; Crumpler, L. S.; Garry, W. B.; Zimbelman, J. R.; Self, S.; Aubele, J. C.

2012-01-01

squeeze-outs along the pit walls that form when the rising crust exposes the still liquid core of the sheet. The plains of Tharsis and Elysium, Mars, display many analogous features

Factors responsible for Ixodes ricinus nymph abundance: Are soil features indicators of tick abundance in a French region where Lyme borreliosis is endemic?

PubMed

Goldstein, Valérie; Boulanger, Nathalie; Schwartz, Dominique; George, Jean-Claude; Ertlen, Damien; Zilliox, Laurence; Schaeffer, Mickaël; Jaulhac, Benoît

2018-05-01

In Europe, the hard tick Ixodes ricinus (Acari: Ixodidae) is the main vector of Lyme borreliosis spirochetes (Borrelia burgdorferi sensu lato group). A field study was conducted to evaluate the abundance of Ixodes nymphs in the French region of Alsace, where Lyme borreliosis is endemic, and to determine whether environmental factors such as soil moisture and composition may be associated with nymph abundance. In the ten sites studied, ticks were collected by drag sampling from March to October in 2013 and 2014. Temperature, relative humidity, saturation deficit, soil pH, humus composition and type of vegetation were recorded at each site. The abundance of I. ricinus was highly variable from one site to another. Inter-annual variations were also observed, since the nymph abundance were higher in 2013 than in 2014. This study shows that humus type can be indicative of nymph abundance. Three types of humus were observed: (1) moder, (2) mull, and (3) mull-moder humus. One of them, moder humus, which is characterized by a thick layer of fragmented leaves, was found in multivariate analyses to be strongly associated with the nymph abundance. This study demonstrates that factors such as saturation deficit do not suffice to explain the differences in nymph abundance among sites. The composition of the soil and especially the type of humus should also be taken into consideration when assessing acarological risk. Copyright © 2018 Elsevier GmbH. All rights reserved.

Subgap Absorption in Conjugated Polymers

DOE R&D Accomplishments Database

Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

1991-01-01

Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

Comparison of low-cost handheld retinal camera and traditional table top retinal camera in the detection of retinal features indicating a risk of cardiovascular disease

NASA Astrophysics Data System (ADS)

Joshi, V.; Wigdahl, J.; Nemeth, S.; Zamora, G.; Ebrahim, E.; Soliz, P.

2018-02-01

Retinal abnormalities associated with hypertensive retinopathy are useful in assessing the risk of cardiovascular disease, heart failure, and stroke. Assessing these risks as part of primary care can lead to a decrease in the incidence of cardiovascular disease-related deaths. Primary care is a resource limited setting where low cost retinal cameras may bring needed help without compromising care. We compared a low-cost handheld retinal camera to a traditional table top retinal camera on their optical characteristics and performance to detect hypertensive retinopathy. A retrospective dataset of N=40 subjects (28 with hypertensive retinopathy, 12 controls) was used from a clinical study conducted at a primary care clinic in Texas. Non-mydriatic retinal fundus images were acquired using a Pictor Plus hand held camera (Volk Optical Inc.) and a Canon CR1-Mark II tabletop camera (Canon USA) during the same encounter. The images from each camera were graded by a licensed optometrist according to the universally accepted Keith-Wagener-Barker Hypertensive Retinopathy Classification System, three weeks apart to minimize memory bias. The sensitivity of the hand-held camera to detect any level of hypertensive retinopathy was 86% compared to the Canon. Insufficient photographer's skills produced 70% of the false negative cases. The other 30% were due to the handheld camera's insufficient spatial resolution to resolve the vascular changes such as minor A/V nicking and copper wiring, but these were associated with non-referable disease. Physician evaluation of the performance of the handheld camera indicates it is sufficient to provide high risk patients with adequate follow up and management.

Ultrasound image features of intravesical prostatic protrusion indicated failure of medication therapy of finasteride and doxazosin in patients with benign prostatic hyperplasia (LUTS/BPH).

PubMed

Liu, Qiang; Zhu, Yunkai; Liu, Jianping; Qi, Jun; Kang, Jian

2017-03-01

Intravesical prostatic protrusion (IPP) is a type of benign prostatic hyperplasia (BPH) adenoma, and it plays a critical role in the pathogenesis of bladder outlet obstruction in patients with lower urinary tract syndromes (LUTS/BPH). The goal of this study was to investigate the effect of a combination therapy with finasteride and doxazosin on IPP in BPU/LUTS patients. A total of 322 BPH patients with enlarged prostatic volume as well as moderate to severe symptom scores were enrolled and divided into four groups according to the degree of IPP (IPP > 10 mm, 5-10 mm, <5 mm and no IPP) in this study. Aggravated International Prostatic Symptom Score (IPSS), acute urinary retention or relevant urinary complications were considered as failure of the therapy. The degrees of IPP were recorded before and after 6 months of treatment. Student's t test and χ 2 were performed between the baseline and endpoint of the therapy. The results showed that the total prostate volume (TPV) and transition zone volume (TZV) of the prostate decreased significantly after 6-month combination therapy (P < 0.05), while no significant changes in IPP were observed at that point (P > 0.05). Failure rates of the medication differed significantly among the four groups. The study indicated that the combination therapy using finasteride and doxazosin could not reduce the degree of IPP. LUTS/BPH patients with IPP which contributes to the failure of medication tend to have a higher risk of progression.

Io: Near-Infrared Absorptions Not Attributable to SO2

NASA Astrophysics Data System (ADS)

Shirley, J. H.; Clark, R. N.; Soderblom, L. A.; Carlson, R. W.; Kamp, L. W.; Galileo NIMS Team

2001-11-01

The Near-Infrared Mapping Spectrometer (NIMS) onboard the Galileo spacecraft imaged the leading side of Jupiter's satellite Io at full spectral resolution and with triple Nyquist spatial sampling during the fifteenth orbital encounter (E15). New despiking and "dejittering" algorithms have been applied to this high S/N observation (15INHRSPEC01A). Spectral absorption features not attributable to SO2 are found between 3.0-3.4 microns and near 4.65 microns. The patterns of the spatial distributions of both absorbers differ from that of the omnipresent SO2. The broad 3.0-3.4 micron absorption is most pronounced in polar regions. Preliminary work suggests that the 4.65 micron feature may be associated with an unidentified sulfate mineral, while the 3.0-3.4 micron feature may result from the presence of more than one absorbing material. Hydrogen-bearing species are likely candidates. For example, H2O ice provides a good match for the absorption near 3.2 microns, but the absorption is shifted to wavelengths longer than that in pure H2O ice. If only one absorber is present, then hydrogen bonding of small numbers of H2O molecules could perhaps account for the shift. The absorption is weak; if H20 related, optical path lengths of a fraction of a micron are indicated. Portions of this research were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Simultaneous infrared and UV-visible absorption spectra of matrix-isolated carbon vapor

NASA Technical Reports Server (NTRS)

Kurtz, Joe; Huffman, Donald R.

1989-01-01

Carbon molecules were suggested as possible carriers of the diffuse interstellar bands. In particular, it was proposed that the 443 nm diffuse interstellar band is due to the same molecule which gives rise to the 447 nm absorption feature in argon matrix-isolated carbon vapor. If so, then an associated C-C stretching mode should be seen in the IR. By doing spectroscopy in both the IR and UV-visible regions on the same sample, the present work provides evidence for correlating UV-visible absorption features with those found in the IR. Early data indicates no correlation between the strongest IR feature (1997/cm) and the 447 nm band. Correlation with weaker IR features is being investigated.

H I absorption in nearby compact radio galaxies

NASA Astrophysics Data System (ADS)

Glowacki, M.; Allison, J. R.; Sadler, E. M.; Moss, V. A.; Curran, S. J.; Musaeva, A.; Deng, C.; Parry, R.; Sligo, M. C.

2017-05-01

H I absorption studies yield information on both active galactic nucleus (AGN) feeding and feedback processes. This AGN activity interacts with the neutral gas in compact radio sources, which are believed to represent the young or recently re-triggered AGN population. We present the results of a survey for H I absorption in a sample of 66 compact radio sources at 0.040 < z < 0.096 with the Australia Telescope Compact Array. In total, we obtained seven detections, five of which are new, with a large range of peak optical depths (3-87 per cent). Of the detections, 71 per cent exhibit asymmetric, broad (ΔvFWHM > 100 km s-1) features, indicative of disturbed gas kinematics. Such broad, shallow and offset features are also found within low-excitation radio galaxies which is attributed to disturbed circumnuclear gas, consistent with early-type galaxies typically devoid of a gas-rich disc. Comparing mid-infrared colours of our galaxies with H I detections indicates that narrow and deep absorption features are preferentially found in late-type and high-excitation radio galaxies in our sample. These features are attributed to gas in galactic discs. By combining XMM-Newton archival data with 21-cm data, we find support that absorbed X-ray sources may be good tracers of H I content within the host galaxy. This sample extends previous H I surveys in compact radio galaxies to lower radio luminosities and provides a basis for future work exploring the higher redshift universe.

Enhanced absorption cycle computer model

NASA Astrophysics Data System (ADS)

Grossman, G.; Wilk, M.

1993-09-01

Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperature boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorption systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system's components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H2O triple-effect cycles, LiCl-H2O solar-powered open absorption cycles, and NH3-H2O single-effect and generator-absorber heat exchange cycles. An appendix contains the user's manual.

Comparison of presenting features, diagnostic tools, hospital outcomes, and quality of care indicators in older (>65 years) to younger, men to women, and diabetics to nondiabetics with acute chest pain triaged in the emergency department.

PubMed

Pelliccia, Francesco; Cartoni, Domenico; Verde, Monica; Salvini, Paolo; Petrolati, Sandro; Mercuro, Giuseppe; Tanzi, Pietro

2004-07-15

In a total of 4,843 consecutive patients admitted to an emergency department (ED) with acute chest pain over a 1-year period, presenting features, diagnostic tools, hospital outcomes, and quality-of-care indicators were compared between older (n = 1,781) and younger (n = 3,062) patients, men (n = 3,095) and women (n = 1,748), and diabetics (n = 856) and nondiabetics (n = 3,987). The results showed that after critical pathway implementation, there was an increase in the use of evidence-based treatment strategies in the ED and improved outcomes in older patients, women, and diabetics, with no more differences in the length of ED stay, diagnostic accuracy for myocardial infarction in the ED, door-to-thrombolysis time, and door-to-balloon time compared with younger patients, men, and nondiabetics.

Nonlinear Absorption and Heating of Dense Plasmas.

DTIC Science & Technology

plasma focus both illuminated by a high intensity CO2 laser. Results indicate the previously noted increases in absorption due to the inclusion of the nonlinear saturation mechanism. The previously obtained increases in absorption with increasing density scale height and decreasing temperatures are also recovered. The

Inherited Fe and Ti electron transition spectroscopic features in altered ultramafic-carbonatite intrusives

NASA Astrophysics Data System (ADS)

Shavers, E. J.; Ghulam, A.; Encarnacion, J. P.

2016-12-01

breccia, and is identified here as the cause of the 690 nm absorption feature. The Ti3+ absorption feature centered near 690 nm and strong Fe absorption features at 890 and 1100 nm may be useful indicators of rare intrusive lithologies in remote geologic mapping.

[Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

PubMed

Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng

2008-07-01

A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

Aerosol Absorption and Radiative Forcing

NASA Technical Reports Server (NTRS)

Stier, Philip; Seinfeld, J. H.; Kinne, Stefan; Boucher, Olivier

2007-01-01

We present a comprehensive examination of aerosol absorption with a focus on evaluating the sensitivity of the global distribution of aerosol absorption to key uncertainties in the process representation. For this purpose we extended the comprehensive aerosol-climate model ECHAM5-HAM by effective medium approximations for the calculation of aerosol effective refractive indices, updated black carbon refractive indices, new cloud radiative properties considering the effect of aerosol inclusions, as well as by modules for the calculation of long-wave aerosol radiative properties and instantaneous aerosol forcing. The evaluation of the simulated aerosol absorption optical depth with the AERONET sun-photometer network shows a good agreement in the large scale global patterns. On a regional basis it becomes evident that the update of the BC refractive indices to Bond and Bergstrom (2006) significantly improves the previous underestimation of the aerosol absorption optical depth. In the global annual-mean, absorption acts to reduce the shortwave anthropogenic aerosol top-of-atmosphere (TOA) radiative forcing clear-sky from -0.79 to -0.53 W m(sup -2) (33%) and all-sky from -0.47 to -0.13W m(sup -2 (72%). Our results confirm that basic assumptions about the BC refractive index play a key role for aerosol absorption and radiative forcing. The effect of the usage of more accurate effective medium approximations is comparably small. We demonstrate that the diversity in the AeroCom land-surface albedo fields contributes to the uncertainty in the simulated anthropogenic aerosol radiative forcings: the usage of an upper versus lower bound of the AeroCom land albedos introduces a global annual-mean TOA forcing range of 0.19W m(sup -2) (36%) clear-sky and of 0.12W m(sup -2) (92%) all-sky. The consideration of black carbon inclusions on cloud radiative properties results in a small global annual-mean all-sky absorption of 0.05W m(sup -2) and a positive TOA forcing perturbation of 0

AERONET derived (BC) aerosol absorption

NASA Astrophysics Data System (ADS)

Kinne, S.

2015-12-01

AERONET is a ground-based sun-/sky-photometer network with good annual statistics at more than 400 sites worldwide. Inversion methods applied to these data define all relevant column aerosol optical properties and reveal even microphysical detail. The extracted data include estimates for aerosol size-distributions and for aerosol refractive indices at four different solar wavelengths. Hereby, the imaginary parts of the refractive indices define the aerosol column absorption. For regional and global averages and radiative impact assessment with off-line radiative transfer, these local data have been extended with distribution patterns offered by AeroCom modeling experiments. Annual and seasonal absorption distributions for total aerosol and estimates for component contributions (such as BC) are presented and associated direct forcing impacts are quantified.

Aerosol Absorption Measurements in MILAGRO.

NASA Astrophysics Data System (ADS)

Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

2007-12-01

During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

Solar absorption surface panel

DOEpatents

Santala, Teuvo J.

1978-01-01

A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

Petawatt laser absorption bounded

PubMed Central

Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

2014-01-01

The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials. PMID:24938656

An Induced Pluripotent Stem Cell Patient Specific Model of Complement Factor H (Y402H) Polymorphism Displays Characteristic Features of Age-Related Macular Degeneration and Indicates a Beneficial Role for UV Light Exposure.

PubMed

Hallam, Dean; Collin, Joseph; Bojic, Sanja; Chichagova, Valeria; Buskin, Adriana; Xu, Yaobo; Lafage, Lucia; Otten, Elsje G; Anyfantis, George; Mellough, Carla; Przyborski, Stefan; Alharthi, Sameer; Korolchuk, Viktor; Lotery, Andrew; Saretzki, Gabriele; McKibbin, Martin; Armstrong, Lyle; Steel, David; Kavanagh, David; Lako, Majlinda

2017-11-01

Age-related macular degeneration (AMD) is the most common cause of blindness, accounting for 8.7% of all blindness globally. Vision loss is caused ultimately by apoptosis of the retinal pigment epithelium (RPE) and overlying photoreceptors. Treatments are evolving for the wet form of the disease; however, these do not exist for the dry form. Complement factor H polymorphism in exon 9 (Y402H) has shown a strong association with susceptibility to AMD resulting in complement activation, recruitment of phagocytes, RPE damage, and visual decline. We have derived and characterized induced pluripotent stem cell (iPSC) lines from two subjects without AMD and low-risk genotype and two patients with advanced AMD and high-risk genotype and generated RPE cells that show local secretion of several proteins involved in the complement pathway including factor H, factor I, and factor H-like protein 1. The iPSC RPE cells derived from high-risk patients mimic several key features of AMD including increased inflammation and cellular stress, accumulation of lipid droplets, impaired autophagy, and deposition of "drüsen"-like deposits. The low- and high-risk RPE cells respond differently to intermittent exposure to UV light, which leads to an improvement in cellular and functional phenotype only in the high-risk AMD-RPE cells. Taken together, our data indicate that the patient specific iPSC model provides a robust platform for understanding the role of complement activation in AMD, evaluating new therapies based on complement modulation and drug testing. Stem Cells 2017;35:2305-2320. © 2017 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Quasar Absorption Studies

NASA Technical Reports Server (NTRS)

Mushotzky, Richard (Technical Monitor); Elvis, Martin

2004-01-01

The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

Site Features

EPA Pesticide Factsheets

This dataset consists of various site features from multiple Superfund sites in U.S. EPA Region 8. These data were acquired from multiple sources at different times and were combined into one region-wide layer.

Nonlinear absorption properties of silicene nanosheets.

PubMed

Zhang, Fang; Wang, Mengxia; Wang, Zhengping; Han, Kezhen; Liu, Xiaojuan; Xu, Xinguang

2018-06-01

As the cousins of graphene, i.e. same group IVA element, the nonlinear absorption (NLA) properties of silicene nanosheets were rarely studied. In this paper, we successfully exfoliated the two-dimensional silicene nanosheets from bulk silicon crystal using liquid phase exfoliation method. The NLA properties of silicene nanosheets were systemically investigated for the first time, as we have known. Silicene performed exciting saturable absorption and two photon absorption (2PA) behavior. The lower saturable intensity and larger 2PA coefficient at 532 nm excitation indicates that silicene has potential application in ultrafast lasers and optical limiting devices, especially in visible waveband.

Nonlinear absorption properties of silicene nanosheets

NASA Astrophysics Data System (ADS)

Zhang, Fang; Wang, Mengxia; Wang, Zhengping; Han, Kezhen; Liu, Xiaojuan; Xu, Xinguang

2018-06-01

As the cousins of graphene, i.e. same group IVA element, the nonlinear absorption (NLA) properties of silicene nanosheets were rarely studied. In this paper, we successfully exfoliated the two-dimensional silicene nanosheets from bulk silicon crystal using liquid phase exfoliation method. The NLA properties of silicene nanosheets were systemically investigated for the first time, as we have known. Silicene performed exciting saturable absorption and two photon absorption (2PA) behavior. The lower saturable intensity and larger 2PA coefficient at 532 nm excitation indicates that silicene has potential application in ultrafast lasers and optical limiting devices, especially in visible waveband.

Compounds affecting cholesterol absorption

NASA Technical Reports Server (NTRS)

Koo, Sung I. (Inventor); Noh, Sang K. (Inventor); Hua, Duy H. (Inventor)

2004-01-01

A class of novel compounds is described for use in affecting lymphatic absorption of cholesterol. Compounds of particular interest are defined by Formula I: ##STR1## or a pharmaceutically acceptable salt thereof.

Absorption heat pump system

DOEpatents

Grossman, Gershon

1984-01-01

The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

Absorption heat pump system

DOEpatents

Grossman, G.

1982-06-16

The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

Laser Atmospheric Absorption Studies.

DTIC Science & Technology

1977-05-01

A. Modification of Commercial C09 Laser 50 B. CW HF/DF Laser System * 53 C. Microcomputer Data Link 55 D . Fourier Transform...improved accuracy are used [5]. c. The absorption coefficient is listed for each absorbing species separately which some codes require. d . A super...series of water vapor absorption measurements was planned. The results of the first four lines studied are presented here in Figures 33a- d . Figure

Solar selective absorption coatings

DOEpatents

Mahoney, Alan R [Albuquerque, NM; Reed, Scott T [Albuquerque, NM; Ashley, Carol S [Albuquerque, NM; Martinez, F Edward [Horseheads, NY

2004-08-31

A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

Solar selective absorption coatings

DOEpatents

Mahoney, Alan R [Albuquerque, NM; Reed, Scott T [Albuquerque, NM; Ashley, Carol S [Albuquerque, NM; Martinez, F Edward [Horseheads, NY

2003-10-14

A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

Absorption fluids data survey

NASA Astrophysics Data System (ADS)

Macriss, R. A.; Zawacki, T. S.

Development of improved data for the thermodynamic, transport and physical properties of absorption fluids were studied. A specific objective of this phase of the study is to compile, catalog and coarse screen the available US data of known absorption fluid systems and publish it as a first edition document to be distributed to manufacturers, researchers and others active in absorption heat pump activities. The methodology and findings of the compilation, cataloguing and coarse screening of the available US data on absorption fluid properties and presents current status and future work on this project are summarized. Both in house file and literature searches were undertaken to obtain available US publications with pertinent physical, thermodynamic and transport properties data for absorption fluids. Cross checks of literature searches were also made, using available published bibliographies and literature review articles, to eliminate secondary sources for the data and include only original sources and manuscripts. The properties of these fluids relate to the liquid and/or vapor state, as encountered in normal operation of absorption equipment employing such fluids, and to the crystallization boundary of the liquid phase, where applicable. The actual data were systematically classified according to the type of fluid and property, as well as temperature, pressure and concentration ranges over which data were available. Data were sought for 14 different properties: Vapor-Liquid Equilibria, Crystallization Temperature, Corrosion Characteristics, Heat of Mixing, Liquid-Phase-Densities, Vapor-Liquid-Phase Enthalpies, Specific Heat, Stability, Viscosity, Mass Transfer Rate, Heat Transfer Rate, Thermal Conductivity, Flammability, and Toxicity.

Time-dependent oral absorption models

NASA Technical Reports Server (NTRS)

Higaki, K.; Yamashita, S.; Amidon, G. L.

2001-01-01

The plasma concentration-time profiles following oral administration of drugs are often irregular and cannot be interpreted easily with conventional models based on first- or zero-order absorption kinetics and lag time. Six new models were developed using a time-dependent absorption rate coefficient, ka(t), wherein the time dependency was varied to account for the dynamic processes such as changes in fluid absorption or secretion, in absorption surface area, and in motility with time, in the gastrointestinal tract. In the present study, the plasma concentration profiles of propranolol obtained in human subjects following oral dosing were analyzed using the newly derived models based on mass balance and compared with the conventional models. Nonlinear regression analysis indicated that the conventional compartment model including lag time (CLAG model) could not predict the rapid initial increase in plasma concentration after dosing and the predicted Cmax values were much lower than that observed. On the other hand, all models with the time-dependent absorption rate coefficient, ka(t), were superior to the CLAG model in predicting plasma concentration profiles. Based on Akaike's Information Criterion (AIC), the fluid absorption model without lag time (FA model) exhibited the best overall fit to the data. The two-phase model including lag time, TPLAG model was also found to be a good model judging from the values of sum of squares. This model also described the irregular profiles of plasma concentration with time and frequently predicted Cmax values satisfactorily. A comparison of the absorption rate profiles also suggested that the TPLAG model is better at prediction of irregular absorption kinetics than the FA model. In conclusion, the incorporation of a time-dependent absorption rate coefficient ka(t) allows the prediction of nonlinear absorption characteristics in a more reliable manner.

Airborne imaging spectrometer data of the Ruby Mountains, Montana: Mineral discrimination using relative absorption band-depth images

USGS Publications Warehouse

Crowley, J.K.; Brickey, D.W.; Rowan, L.C.

1989-01-01

Airborne imaging spectrometer data collected in the near-infrared (1.2-2.4 ??m) wavelength range were used to study the spectral expression of metamorphic minerals and rocks in the Ruby Mountains of southwestern Montana. The data were analyzed by using a new data enhancement procedure-the construction of relative absorption band-depth (RBD) images. RBD images, like bandratio images, are designed to detect diagnostic mineral absorption features, while minimizing reflectance variations related to topographic slope and albedo differences. To produce an RBD image, several data channels near an absorption band shoulder are summed and then divided by the sum of several channels located near the band minimum. RBD images are both highly specific and sensitive to the presence of particular mineral absorption features. Further, the technique does not distort or subdue spectral features as sometimes occurs when using other data normalization methods. By using RBD images, a number of rock and soil units were distinguished in the Ruby Mountains including weathered quartz - feldspar pegmatites, marbles of several compositions, and soils developed over poorly exposed mica schists. The RBD technique is especially well suited for detecting weak near-infrared spectral features produced by soils, which may permit improved mapping of subtle lithologic and structural details in semiarid terrains. The observation of soils rich in talc, an important industrial commodity in the study area, also indicates that RBD images may be useful for mineral exploration. ?? 1989.

Implications of high-velocity interstellar H I absorption features

NASA Technical Reports Server (NTRS)

Cowie, L.; York, D. G.; Laurent, C.; Vidal-Madjar, A.

1979-01-01

Contributions to the interstellar H I column density at high velocities from immediate postshock gas and from the cooling gas behind a shock are compared. The detection of high-velocity H I in L-epsilon and L-delta for Iota Ori is reported and interpreted as cooling gas behind a shock of 100 km/s velocity. The immediate postshock gas should be observable for shock velocities greater than 200 km/s and permits direct determination of the velocities of adiabatic shocks in the interstellar medium. It is pointed out that interstellar L-alpha and L-beta lines may not have purely Lorentzian profiles if high-velocity H I is a widespread phenomenon.

Absorption Spectra of Gold Nanoparticle Suspensions

NASA Astrophysics Data System (ADS)

Anan'eva, M. V.; Nurmukhametov, D. R.; Zverev, A. S.; Nelyubina, N. V.; Zvekov, A. A.; Russakov, D. M.; Kalenskii, A. V.; Eremenko, A. N.

2018-02-01

Three gold nanoparticle suspensions are obtained, and mean radii in distributions - (6.1 ± 0.2), (11.9 ± 0.3), and (17.3 ± 0.7) nm - are determined by the transmission electron microscopy method. The optical absorption spectra of suspensions are obtained and studied. Calculation of spectral dependences of the absorption index of suspensions at values of the gold complex refractive index taken from the literature showed a significant deviation of experimental and calculated data in the region of 450-800 nm. Spectral dependences of the absorption of suspensions are simulated within the framework of the Mie-Drude theory taking into account the interband absorption in the form of an additional term in the imaginary part of the dielectric permittivity of the Gaussian type. It is shown that to quantify the spectral dependences in the region of the plasmon absorption band of nanoparticles, correction of the parameters of the interband absorption is necessary in addition to the increase of the relaxation parameter of the Drude theory. Spectral dependences of the dielectric permittivity of gold in nanodimensional state are refined from the solution of the inverse problem. The results of the present work are important for predicting the special features of operation of photonic devices and optical detonators based on gold nanoparticles.

Rocket-borne instrumentation using the resonant absorption technique to study the geocoronal and interplanetary helium emissions.

PubMed

Crifo, J F; Fahr, H J; Seidi, P; Wulf-Mathies, C

1979-09-01

A rocket payload able to perform a thorough and independent analysis of the He I 58.43340-nm geocoronal and interplanetary emissions is presented. It includes a sun-pointed resonant absorption spectrometer and a sky-scanning resonant absorption photometer. Both incorporate a similar helium resonance cell of original design featuring a most flexible pressure scanning capability and an accurate pressure measuring device, so that scanning by wavelength bandpasses from 20 down to 1 pm can be achieved. A description of the design and calibration of the instrument is given, followed by an indication of its successful operation in flight.

Seven-effect absorption refrigeration

DOEpatents

DeVault, Robert C.; Biermann, Wendell J.

1989-01-01

A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

Seven-effect absorption refrigeration

DOEpatents

DeVault, R.C.; Biermann, W.J.

1989-05-09

A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

Optical Hydrogen Absorption Consistent with a Thin Bow Shock Leading the Hot Jupiter HD 189733b

NASA Astrophysics Data System (ADS)

Cauley, P. Wilson; Redfield, Seth; Jensen, Adam G.; Barman, Travis; Endl, Michael; Cochran, William D.

2015-09-01

Bow shocks are ubiquitous astrophysical phenomena resulting from the supersonic passage of an object through a gas. Recently, pre-transit absorption in UV metal transitions of the hot Jupiter (HJ) exoplanets HD 189733b and WASP12-b have been interpreted as being caused by material compressed in a planetary bow shock. Here we present a robust detection of a time-resolved pre-transit, as well as in-transit absorption signature around the HJ exoplanet HD 189733b using high spectral resolution observations of several hydrogen Balmer lines. The line shape of the pre-transit feature and the shape of the timeseries absorption provide the strongest constraints on the morphology and physical characteristics of extended structures around an exoplanet. The in-transit measurements confirm the previous exospheric Hα detection, although the absorption depth measured here is ∼50% lower. The pre-transit absorption feature occurs 125 minutes before the predicted optical transit, a projected linear distance from the planet to the stellar disk of 7.2 Rp. The absorption strength observed in the Balmer lines indicates an optically thick, but physically small, geometry. We model this signal as the early ingress of a planetary bow shock. If the bow shock is mediated by a planetary magnetosphere, the large standoff distance derived from the model suggests a large planetary magnetic field strength of Beq = 28 G. Better knowledge of exoplanet magnetic field strengths is crucial to understanding the role these fields play in planetary evolution and the potential development of life on planets in the habitable zone.

OPTICAL HYDROGEN ABSORPTION CONSISTENT WITH A THIN BOW SHOCK LEADING THE HOT JUPITER HD 189733B

SciTech Connect

Cauley, P. Wilson; Redfield, Seth; Jensen, Adam G.

Bow shocks are ubiquitous astrophysical phenomena resulting from the supersonic passage of an object through a gas. Recently, pre-transit absorption in UV metal transitions of the hot Jupiter (HJ) exoplanets HD 189733b and WASP12-b have been interpreted as being caused by material compressed in a planetary bow shock. Here we present a robust detection of a time-resolved pre-transit, as well as in-transit absorption signature around the HJ exoplanet HD 189733b using high spectral resolution observations of several hydrogen Balmer lines. The line shape of the pre-transit feature and the shape of the timeseries absorption provide the strongest constraints on themore » morphology and physical characteristics of extended structures around an exoplanet. The in-transit measurements confirm the previous exospheric Hα detection, although the absorption depth measured here is ∼50% lower. The pre-transit absorption feature occurs 125 minutes before the predicted optical transit, a projected linear distance from the planet to the stellar disk of 7.2 R{sub p}. The absorption strength observed in the Balmer lines indicates an optically thick, but physically small, geometry. We model this signal as the early ingress of a planetary bow shock. If the bow shock is mediated by a planetary magnetosphere, the large standoff distance derived from the model suggests a large planetary magnetic field strength of B{sub eq} = 28 G. Better knowledge of exoplanet magnetic field strengths is crucial to understanding the role these fields play in planetary evolution and the potential development of life on planets in the habitable zone.« less

Multiplexed absorption tomography with calibration-free wavelength modulation spectroscopy

SciTech Connect

Cai, Weiwei; Kaminski, Clemens F., E-mail: cfk23@cam.ac.uk

2014-04-14

We propose a multiplexed absorption tomography technique, which uses calibration-free wavelength modulation spectroscopy with tunable semiconductor lasers for the simultaneous imaging of temperature and species concentration in harsh combustion environments. Compared with the commonly used direct absorption spectroscopy (DAS) counterpart, the present variant enjoys better signal-to-noise ratios and requires no baseline fitting, a particularly desirable feature for high-pressure applications, where adjacent absorption features overlap and interfere severely. We present proof-of-concept numerical demonstrations of the technique using realistic phantom models of harsh combustion environments and prove that the proposed techniques outperform currently available tomography techniques based on DAS.

Absorption heat pump system

DOEpatents

Grossman, Gershon; Perez-Blanco, Horacio

1984-01-01

An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

Absorption Heat Pump Cycles

NASA Astrophysics Data System (ADS)

Kunugi, Yoshifumi; Kashiwagi, Takao

Various advanced absorption cycles are studied, developed and invented. In this paper, their cycles are classified and arranged using the three categories: effect, stage and loop, then an outline of the cycles are explained on the Duehring diagram. Their cycles include high COP cycles for refrigerations and heat pumps, high temperature lift cycles for heat transformer, absorption-compression hybrid cycles and heat pump transformer cycle. The highest COPi is attained by the seven effect cycle. In addition, the cycles for low temperature are invented and explained. Furthermore the power generation • refrigeration cycles are illustrated.

Community indicators

PubMed Central

Flynn, Andrea; Wells, Samantha

2014-01-01

Community indicators are used to assess the impact of alcohol on communities. This article reviews the main data sources for community indicators, discusses their strengths and limitations, and discusses indicators used in reference to four main topics relating to alcohol use and problems at the community level: alcohol use, patterns, and problems; alcohol availability; alcohol-related health outcomes/trauma; and alcohol-related crime and enforcement. It also reviews the challenges associated with collecting community indicator data, along with important innovations in the field that have contributed to better knowledge of how to collect and analyze community-level data on the impact of alcohol. PMID:24881322

Laser Absorption by Over-Critical Plasmas

NASA Astrophysics Data System (ADS)

May, J.; Tonge, J.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.; Mori, W. B.

2015-11-01

Absorption of high intensity laser light by matter has important applications to emerging sciences and technology, such as Fast Ignition ICF and ion acceleration. As such, understanding the underlying mechanisms of this absorption is key to developing these technologies. Critical features which distinguish the interaction of high intensity light - defined here as a laser field having a normalized vector potential greater than unity - are that the reaction of the material to the fields results in sharp high-density interfaces; and that the movement of the electrons is in general relativistic, both in a fluid and a thermal sense. The results of these features are that the absorption mechanisms are qualitatively distinct from those at lower intensities. We will review previous work, by our group and others, on the absorption mechanisms, and highlight current research. We will show that the standing wave structure of the reflected laser light is key to particle dynamics for normally incident lasers. The authors acknowledge the support of the Department of Energy under contract DE-NA 0001833 and the National Science Foundation under contract ACI 1339893.

Two-Phonon Absorption

ERIC Educational Resources Information Center

Hamilton, M. W.

2007-01-01

A nonlinear aspect of the acousto-optic interaction that is analogous to multi-photon absorption is discussed. An experiment is described in which the second-order acousto-optically scattered intensity is measured and found to scale with the square of the acoustic intensity. This experiment using a commercially available acousto-optic modulator is…

A search for formic acid in the upper troposphere - A tentative identification of the 1105-per cm nu-6 band Q branch in high-resolution balloon-borne solar absorption spectra

NASA Technical Reports Server (NTRS)

Goldman, A.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

1984-01-01

Infrared solar absorption spectra recorded at 0.02-per cm resolution during a balloon flight from Alamogordo, NM (33 deg N), on March 23, 1981, have been analyzed for the possible presence of absorption by formic acid (HCOOH). An absorption feature at 1105 per cm has been tentatively identified in upper tropospheric spectra as due to the nu-6 band Q branch. A preliminary analysis indicates a concentration of about 0.6 ppbv and 0.4 ppbv near 8 and 10 km, respectively.

A search for intervening HI absorption

NASA Astrophysics Data System (ADS)

Reeves, Sarah N.; Sadler, Elaine M.; Allison, James R.; Koribalski, Baerbel S.; Curran, Stephen J.

2013-03-01

HI absorption-line studies provide a unique probe of the gas distribution and kinematics in galaxies well beyond the local universe (z ≳ 0.3). HI absorption-line surveys with next-generation radio telescopes will provide the first large-scale studies of HI in a redshift regime which is poorly understood. However, we currently lack the understanding to infer galaxy properties from absorption-line observations alone. To address this issue, we are conducting a search for intervening HI absorption in a sample of 20 nearby galaxies. Our aim is to investigate how the detection rate varies with distance from the galaxy. We target sight-lines to bright continuum sources, which intercept known gas-rich galaxies, selected from the HIPASS Bright Galaxy Catalogue (Koribalski et al. 2004). In our pilot sample, six galaxies with impact parameters < 20 kpc, we do not detect any absorption lines - although all are detected in 21cm emission. This indicates that an absorption non-detection cannot simply be interpreted as an absence of neutral gas - see Fig. 1. Our detection rate is low compared to previous surveys e.g. Gupta et al. (2010). This is, at least partially, due to the high resolution of the observations reducing the flux of the background source, which will also be an issue in future surveys, such as ASKAP-FLASH.

Effect of in-material losses on terahertz absorption, transmission, and reflection in photonic crystals made of polar dielectrics

SciTech Connect

Serebryannikov, Andriy E., E-mail: andser@amu.edu.pl; Nanotechnology Research Center—NANOTAM, Bilkent University, 06800 Ankara; Nojima, S.

2015-10-07

The effect of the material absorption factor on terahertz absorption (A), transmittance (T), and reflectance (R) for slabs of PhC that comprise rods made of GaAs, a polar dielectric, is studied. The main goal was to illustrate how critical a choice of the absorption factor for simulations is and to indicate the importance of the possible modification of the absorption ability by using either active or lossy impurities. The spectra of A, T, and R are strongly sensitive to the location of the polaritonic gap with respect to the photonic pass and stop bands connected with periodicity that enables themore » efficient combination of the effects of material and structural parameters. It will be shown that the spectra can strongly depend on the utilized value of the material absorption factor. In particular, both narrow and wide absorption bands may appear owing to a variation of the material parameters with a frequency in the vicinity of the polaritonic gap. The latter are often achieved at wideband suppression of transmission, so that an ultra-wide stop band can appear as a result of adjustment of the stop bands having different origin. The results obtained at simultaneous variation of the absorption factor and frequency, and angle of incidence and frequency, indicate the possibility of the existence of wide ranges of tolerance, in which the basic features do remain. This allows for mitigating the accuracy requirements for the absorption factor in simulations and promises the efficient absorption of nonmonochromatic waves and beams with a wide angular spectrum. Suppression of narrowband effects in transmission is demonstrated at rather large values of the absorption factor, when they appear due to either the defect modes related to structural defects or dispersion inspired variations of the material parameters in the vicinity of the polaritonic gap. Comparison with auxiliary structures helps one to detect the common features and differences of homogeneous slabs and

Evolutionary synthesis of simple stellar populations. Colours and indices

NASA Astrophysics Data System (ADS)

Kurth, O. M.; Fritze-v. Alvensleben, U.; Fricke, K. J.

1999-07-01

We construct evolutionary synthesis models for simple stellar populations using the evolutionary tracks from the Padova group (1993, 1994), theoretical colour calibrations from \\cite[Lejeune et al. (1997, 1998)]{lejeune} and fit functions for stellar atmospheric indices from \\cite[Worthey et al. (1994)]{worthey}. A Monte-Carlo technique allows us to obtain a smooth time evolution of both broad band colours in UBVRIK and a series of stellar absorption features for Single Burst Stellar Populations (SSPs). We present colours and indices for SSPs with ages from 1 \\ 10(9) yrs to 1.6 \\ 10(10) yrs and metallicities [M/H]=-2.3, -1.7, -0.7, -0.4, 0.0 and 0.4. Model colours and indices at an age of about a Hubble time are in good agreement with observed colours and indices of the Galactic and M 31 GCs.

69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

Linear absorptive dielectrics

NASA Astrophysics Data System (ADS)

Tip, A.

1998-06-01

Starting from Maxwell's equations for a linear, nonconducting, absorptive, and dispersive medium, characterized by the constitutive equations D(x,t)=ɛ1(x)E(x,t)+∫t-∞dsχ(x,t-s)E(x,s) and H(x,t)=B(x,t), a unitary time evolution and canonical formalism is obtained. Given the complex, coordinate, and frequency-dependent, electric permeability ɛ(x,ω), no further assumptions are made. The procedure leads to a proper definition of band gaps in the periodic case and a new continuity equation for energy flow. An S-matrix formalism for scattering from lossy objects is presented in full detail. A quantized version of the formalism is derived and applied to the generation of Čerenkov and transition radiation as well as atomic decay. The last case suggests a useful generalization of the density of states to the absorptive situation.

Vehicular impact absorption system

NASA Technical Reports Server (NTRS)

Knoell, A. C.; Wilson, A. H. (Inventor)

1978-01-01

An improved vehicular impact absorption system characterized by a plurality of aligned crash cushions of substantially cubic configuration is described. Each consists of a plurality of voided aluminum beverage cans arranged in substantial parallelism within a plurality of superimposed tiers and a covering envelope formed of metal hardware cloth. A plurality of cables is extended through the cushions in substantial parallelism with an axis of alignment for the cushions adapted to be anchored at each of the opposite end thereof.

Vertical Feature Mask Feature Classification Flag Extraction

Atmospheric Science Data Center

2013-03-28

  Vertical Feature Mask Feature Classification Flag Extraction This routine demonstrates extraction of the ... in a CALIPSO Lidar Level 2 Vertical Feature Mask feature classification flag value. It is written in Interactive Data Language (IDL) ...

Health Care Indicators

PubMed Central

Donham, Carolyn S.; Letsch, Suzanne W.; Maple, Brenda T.; Singer, Naphtale; Cowan, Cathy A.

1991-01-01

Contained in this regular feature of the journal is a section on each of the following four topics community hospital statistics; employment, hours, and earnings in the private health sector; prices; and national economic indicators. These statistics are valuable in their own right for understanding the relationship between the health care sector and the overall economy. In addition, they provide indicators of the direction and magnitude of health care costs prior to the availability of more comprehensive data. PMID:10112766

Time-varying sodium absorption in the Type Ia supernova 2013gh

DOE PAGES

Ferretti, Raphael; Amanullah, R.; Goobar, A.; ...

2016-07-18

Context. Temporal variability of narrow absorption lines in high-resolution spectra of Type Ia supernovae (SNe Ia) is studied to search for circumstellar matter. Time series which resolve the profiles of absorption lines such as Na I D or Ca II H&K are expected to reveal variations due to photoionisation and subsequent recombination of the gases. The presence, composition, and geometry of circumstellar matter may hint at the elusive progenitor system of SNe Ia and could also affect the observed reddening law. Aims. To date, there are few known cases of time-varying Na I D absorption in SNe Ia, all ofmore » which occurred during relatively late phases of the supernova (SN) evolution. Photoionisation, however, is predicted to occur during the early phases of SNe Ia, when the supernovae peak in the ultraviolet. We attempt, therefore, to observe early-time absorption-line variations by obtaining high-resolution spectra of SNe before maximum light. Methods. In this paper, we have obtained photometry and high-resolution spectroscopy of SNe Ia 2013gh and iPTF 13dge, to search for absorption-line variations. Furthermore, we study interstellar absorption features in relation to the observed photometric colours of the SNe. Results. Both SNe display deep Na I D and Ca II H&K absorption features. Furthermore, small but significant variations are detected in a feature of the Na I D profile of SN 2013gh. The variations are consistent with either geometric effects of rapidly moving or patchy gas clouds or photoionisation of Na I gas at R ≈ 10 19 cm from the explosion. Conclusions. Our analysis indicates that it is necessary to focus on early phases to detect photoionisation effects of gases in the circumstellar medium of SNe Ia. Different absorbers such as Na I and Ca II can be used to probe for matter at different distances from the SNe. Finally, the nondetection of variations during early phases makes it possible to put limits on the abundance of the species at those

Time-varying sodium absorption in the Type Ia supernova 2013gh

NASA Astrophysics Data System (ADS)

Ferretti, R.; Amanullah, R.; Goobar, A.; Johansson, J.; Vreeswijk, P. M.; Butler, R. P.; Cao, Y.; Cenko, S. B.; Doran, G.; Filippenko, A. V.; Freeland, E.; Hosseinzadeh, G.; Howell, D. A.; Lundqvist, P.; Mattila, S.; Nordin, J.; Nugent, P. E.; Petrushevska, T.; Valenti, S.; Vogt, S.; Wozniak, P.

2016-07-01

Context. Temporal variability of narrow absorption lines in high-resolution spectra of Type Ia supernovae (SNe Ia) is studied to search for circumstellar matter. Time series which resolve the profiles of absorption lines such as Na I D or Ca II H&K are expected to reveal variations due to photoionisation and subsequent recombination of the gases. The presence, composition, and geometry of circumstellar matter may hint at the elusive progenitor system of SNe Ia and could also affect the observed reddening law. Aims: To date, there are few known cases of time-varying Na I D absorption in SNe Ia, all of which occurred during relatively late phases of the supernova (SN) evolution. Photoionisation, however, is predicted to occur during the early phases of SNe Ia, when the supernovae peak in the ultraviolet. We attempt, therefore, to observe early-time absorption-line variations by obtaining high-resolution spectra of SNe before maximum light. Methods: We have obtained photometry and high-resolution spectroscopy of SNe Ia 2013gh and iPTF 13dge, to search for absorption-line variations. Furthermore, we study interstellar absorption features in relation to the observed photometric colours of the SNe. Results: Both SNe display deep Na I D and Ca II H&K absorption features. Furthermore, small but significant variations are detected in a feature of the Na I D profile of SN 2013gh. The variations are consistent with either geometric effects of rapidly moving or patchy gas clouds or photoionisation of Na I gas at R ≈ 1019 cm from the explosion. Conclusions: Our analysis indicates that it is necessary to focus on early phases to detect photoionisation effects of gases in the circumstellar medium of SNe Ia. Different absorbers such as Na I and Ca II can be used to probe for matter at different distances from the SNe. The nondetection of variations during early phases makes it possible to put limits on the abundance of the species at those distances. Full Tables 2 and 3 are only

Position indicator

DOEpatents

Tanner, David E.

1981-01-01

A nuclear reactor system is described in which a position indicator is provided for detecting and indicating the position of a movable element inside a pressure vessel. The movable element may be a valve element or similar device which moves about an axis. Light from a light source is transmitted from a source outside the pressure vessel to a first region inside the pressure vessel in alignment with the axis of the movable element. The light is redirected by a reflector prism to a second region displaced radially from the first region. The reflector prism moves in response to movement of the movable element about its axis such that the second region moves arcuately with respect to the first region. Sensors are arrayed in an arc corresponding to the arc of movement of the second region and signals are transmitted from the sensors to the exterior of the reactor vessel to provide indication of the position of the movable element.

SHARDS: Survey for High-z Absorption Red & Dead Sources

NASA Astrophysics Data System (ADS)

Pérez-González, P. G.; Cava, A.

2013-05-01

SHARDS, an ESO/GTC Large Program, is an ultra-deep (26.5 mag) spectro-photometric survey with GTC/OSIRIS designed to select and study massive passively evolving galaxies at z=1.0-2.3 in the GOODS-N field using a set of 24 medium-band filters (FWHM~17 nm) covering the 500-950 nm spectral range. Our observing strategy has been planned to detect, for z>1 sources, the prominent Mg absorption feature (at rest-frame ~280 nm), a distinctive, necessary, and sufficient feature of evolved stellar populations (older than 0.5 Gyr). These observations are being used to: (1) derive for the first time an unbiased sample of high-z quiescent galaxies, which extends to fainter magnitudes the samples selected with color techniques and spectroscopic surveys; (2) derive accurate ages and stellar masses based on robust measurements of spectral features such as the Mg_UV or D(4000) indices; (3) measure their redshift with an accuracy Δz/(1+z)<0.02; and (4) study emission-line galaxies (starbursts and AGN) up to very high redshifts. The well-sampled optical SEDs provided by SHARDS for all sources in the GOODS-N field are a valuable complement for current and future surveys carried out with other telescopes (e.g., Spitzer, HST, and Herschel).

Percutaneous absorption of selenium sulfide

SciTech Connect

Farley, J.; Skelly, E.M.; Weber, C.B.

1986-01-01

The purpose of this study was to determine selenium levels in the urine of Tinea patients before and after overnight application of a 2.5% selenium sulfide lotion. Selenium was measured by atomic absorption spectroscopy (AAS). Hydride generation and carbon rod atomization were studied. It was concluded from this study that selenium is absorbed through intact skin. Selenium is then excreted, at least partially, in urine, for at least a week following treatment. The data show that absorption and excretion of selenium vary on an individual basis. Selenium levels in urine following a single application of selenium sulfide lotion do notmore » indicate that toxic amounts of selenium are being absorbed. Repeated treatments with SeS/sub 2/ result in selenium concentrations in urine which are significantly higher than normal. Significant matrix effects are observed in the carbon rod atomization of urine samples for selenium determinations, even in the presence of a matrix modifier such as nickel. The method of standard additions is required to obtain accurate results in the direct determination of selenium in urine by carbon rod AAS.« less

UV laser long-path absorption spectroscopy

NASA Technical Reports Server (NTRS)

Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf

1994-01-01

Long path Differential Optical Absorption Spectroscopy (DOAS) using a picosecond UV laser as a light source was developed in our institute. Tropospheric OH radicals are measured by their rotational absorption lines around 308 nm. The spectra are obtained using a high resolution spectrograph. The detection system has been improved over the formerly used optomechanical scanning device by application of a photodiode array which increased the observed spectral range by a factor of 6 and which utilizes the light much more effectively leading to a considerable reduction of the measurement time. This technique provides direct measurements of OH because the signal is given by the product of the absorption coefficient and the OH concentration along the light path according to Lambert-Beers law. No calibration is needed. Since the integrated absorption coefficient is well known the accuracy of the measurement essentially depends on the extent to which the OH absorption pattern can be detected in the spectra. No interference by self generated OH radicals in the detection lightpath has been observed. The large bandwidth (greater than 0.15 nm) and the high spectral resolution (1.5 pm) allows absolute determination of interferences by other trace gas absorptions. The measurement error is directly accessible from the absorption-signal to baseline-noise ratio in the spectra. The applicability of the method strongly depends on visibility. Elevated concentrations of aerosols lead to considerable attenuation of the laser light which reduces the S/N-ratio. In the moderately polluted air of Julich, where we performed a number of OH measurement spectra. In addition absorption features of unidentified species were frequently detected. A quantitative deconvolution even of the known species is not easy to achieve and can leave residual structures in the spectra. Thus interferences usually increase the noise and deteriorate the OH detection sensitivity. Using diode arrays for sensitive

Ganges Features

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] Context image for PIA03285 Ganges Features

This image shows part of Ganges Chasma. Several landslides occur at the top of the image, while dunes and canyon floor deposits are visible at the bottom of the image.

Image information: VIS instrument. Latitude -6.8N, Longitude 312.2E. 17 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Corrosion Problems in Absorption Chillers

ERIC Educational Resources Information Center

Stetson, Bruce

1978-01-01

Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

Chemical Indicators.

ERIC Educational Resources Information Center

Prombain, Dorothy R.; And Others

This science sourcebook was written for intermediate grade teachers to provide guidance in teaching a specially developed unit on chemical indicators. Directions and suggestions for guiding student science activities are given. Some of the activities concern soil testing, crystals, and household powders such as sugar and salt. A list of necessary…

[The study of CO2 cavity enhanced absorption and highly sensitive absorption spectroscopy].

PubMed

Pei, Shi-Xin; Gao, Xiao-Ming; Cui, Fen-Ping; Huang, Wei; Shao, Jie; Fan, Hong; Zhang, Wei-Jun

2005-12-01

Cavity enhanced absorption spectroscopy (CEAS) is a new spectral technology that is based on the cavity ring down absorption spectroscopy. In the present paper, a DFB encapsulation narrow line width tunable diode laser (TDL) was used as the light source. At the center output, the TDL radiation wavelength was 1.573 microm, and an optical cavity, which consisted of two high reflectivity mirrors (near 1.573 microm, the mirror reflectivity was about 0.994%), was used as a sample cell. A wavemeter was used to record the accurate frequency of the laser radiation. In the experiment, the method of scanning the optical cavity to change the cavity mode was used, when the laser frequency was coincident with one of the cavity mode; the laser radiation was coupled into the optical cavity and the detector could receive the light signals that escaped the optical cavity. As a result, the absorption spectrum of carbon dioxide weak absorption at low pressure was obtained with an absorption intensity of 1.816 x 10(-23) cm(-1) x (molecule x cm(-2)(-1) in a sample cell with a length of only 33.5 cm. An absorption sensitivity of about 3.62 x 10(-7) cm(-1) has been achieved. The experiment result indicated that the cavity enhanced absorption spectroscopy has the advantage of high sensivity, simple experimental setup, and easy operation.

Mathematical model of zinc absorption: effects of dietary calcium, protein and iron on zinc absorption

PubMed Central

Miller, Leland V.; Krebs, Nancy F.; Hambidge, K. Michael

2013-01-01

A previously described mathematical model of Zn absorption as a function of total daily dietary Zn and phytate was fitted to data from studies in which dietary Ca, Fe and protein were also measured. An analysis of regression residuals indicated statistically significant positive relationships between the residuals and Ca, Fe and protein, suggesting that the presence of any of these dietary components enhances Zn absorption. Based on the hypotheses that (1) Ca and Fe both promote Zn absorption by binding with phytate and thereby making it unavailable for binding Zn and (2) protein enhances the availability of Zn for transporter binding, the model was modified to incorporate these effects. The new model of Zn absorption as a function of dietary Zn, phytate, Ca, Fe and protein was then fitted to the data. The proportion of variation in absorbed Zn explained by the new model was 0·88, an increase from 0·82 with the original model. A reduced version of the model without Fe produced an equally good fit to the data and an improved value for the model selection criterion, demonstrating that when dietary Ca and protein are controlled for, there is no evidence that dietary Fe influences Zn absorption. Regression residuals and testing with additional data supported the validity of the new model. It was concluded that dietary Ca and protein modestly enhanced Zn absorption and Fe had no statistically discernable effect. Furthermore, the model provides a meaningful foundation for efforts to model nutrient interactions in mineral absorption. PMID:22617116

Mathematical model of zinc absorption: effects of dietary calcium, protein and iron on zinc absorption.

PubMed

Miller, Leland V; Krebs, Nancy F; Hambidge, K Michael

2013-02-28

A previously described mathematical model of Zn absorption as a function of total daily dietary Zn and phytate was fitted to data from studies in which dietary Ca, Fe and protein were also measured. An analysis of regression residuals indicated statistically significant positive relationships between the residuals and Ca, Fe and protein, suggesting that the presence of any of these dietary components enhances Zn absorption. Based on the hypotheses that (1) Ca and Fe both promote Zn absorption by binding with phytate and thereby making it unavailable for binding Zn and (2) protein enhances the availability of Zn for transporter binding, the model was modified to incorporate these effects. The new model of Zn absorption as a function of dietary Zn, phytate, Ca, Fe and protein was then fitted to the data. The proportion of variation in absorbed Zn explained by the new model was 0·88, an increase from 0·82 with the original model. A reduced version of the model without Fe produced an equally good fit to the data and an improved value for the model selection criterion, demonstrating that when dietary Ca and protein are controlled for, there is no evidence that dietary Fe influences Zn absorption. Regression residuals and testing with additional data supported the validity of the new model. It was concluded that dietary Ca and protein modestly enhanced Zn absorption and Fe had no statistically discernable effect. Furthermore, the model provides a meaningful foundation for efforts to model nutrient interactions in mineral absorption.

DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE

SciTech Connect

Espada, D.; Matsushita, S.; Sakamoto, K.

2010-09-01

We report on atomic gas (H I) and molecular gas (as traced by CO(2-1)) redshifted absorption features toward the nuclear regions of the closest powerful radio galaxy, Centaurus A (NGC 5128). Our H I observations using the Very Long Baseline Array allow us to discern with unprecedented sub-parsec resolution H I absorption profiles toward different positions along the 21 cm continuum jet in the inner 0.''3 (or 5.4 pc). In addition, our CO(2-1) data obtained with the Submillimeter Array probe the bulk of the absorbing molecular gas with little contamination by emission, which was not possible with previous CO single-dishmore » observations. We shed light on the physical properties of the gas in the line of sight with these data, emphasizing the still open debate about the nature of the gas that produces the broad absorption line ({approx}55 km s{sup -1}). First, the broad H I line is more prominent toward the central and brightest 21 cm continuum component than toward a region along the jet at a distance {approx}20 mas (or 0.4 pc) further from the nucleus. This indicates that the broad absorption line arises from gas located close to the nucleus, rather than from diffuse and more distant gas. Second, the different velocity components detected in the CO(2-1) absorption spectrum match well with other molecular lines, such as those of HCO{sup +}(1-0), except the broad absorption line that is detected in HCO{sup +}(1-0) (and most likely related to that of the H I). Dissociation of molecular hydrogen due to the active galactic nucleus seems to be efficient at distances r {approx}< 10 pc, which might contribute to the depth of the broad H I and molecular lines.« less

Exciton absorption of entangled photons in semiconductor quantum wells

NASA Astrophysics Data System (ADS)

Rodriguez, Ferney; Guzman, David; Salazar, Luis; Quiroga, Luis; Condensed Matter Physics Group Team

2013-03-01

The dependence of the excitonic two-photon absorption on the quantum correlations (entanglement) of exciting biphotons by a semiconductor quantum well is studied. We show that entangled photon absorption can display very unusual features depending on space-time-polarization biphoton parameters and absorber density of states for both bound exciton states as well as for unbound electron-hole pairs. We report on the connection between biphoton entanglement, as quantified by the Schmidt number, and absorption by a semiconductor quantum well. Comparison between frequency-anti-correlated, unentangled and frequency-correlated biphoton absorption is addressed. We found that exciton oscillator strengths are highly increased when photons arrive almost simultaneously in an entangled state. Two-photon-absorption becomes a highly sensitive probe of photon quantum correlations when narrow semiconductor quantum wells are used as two-photon absorbers. Research funds from Facultad de Ciencias, Universidad de los Andes

Efficient energy absorption of intense ps-laser pulse into nanowire target

NASA Astrophysics Data System (ADS)

Habara, H.; Honda, S.; Katayama, M.; Sakagami, H.; Nagai, K.; Tanaka, K. A.

2016-06-01

The interaction between ultra-intense laser light and vertically aligned carbon nanotubes is investigated to demonstrate efficient laser-energy absorption in the ps laser-pulse regime. Results indicate a clear enhancement of the energy conversion from laser to energetic electrons and a simultaneously small plasma expansion on the surface of the target. A two-dimensional plasma particle calculation exhibits a high absorption through laser propagation deep into the nanotube array, even for a dense array whose structure is much smaller than the laser wavelength. The propagation leads to the radial expansion of plasma perpendicular to the nanotubes rather than to the front side. These features may contribute to fast ignition in inertial confinement fusion and laser particle acceleration, both of which require high current and small surface plasma simultaneously.

Efficient energy absorption of intense ps-laser pulse into nanowire target

SciTech Connect

Habara, H.; Honda, S.; Katayama, M.

The interaction between ultra-intense laser light and vertically aligned carbon nanotubes is investigated to demonstrate efficient laser-energy absorption in the ps laser-pulse regime. Results indicate a clear enhancement of the energy conversion from laser to energetic electrons and a simultaneously small plasma expansion on the surface of the target. A two-dimensional plasma particle calculation exhibits a high absorption through laser propagation deep into the nanotube array, even for a dense array whose structure is much smaller than the laser wavelength. The propagation leads to the radial expansion of plasma perpendicular to the nanotubes rather than to the front side. Thesemore » features may contribute to fast ignition in inertial confinement fusion and laser particle acceleration, both of which require high current and small surface plasma simultaneously.« less

Imaging electronic trap states in perovskite thin films with combined fluorescence and femtosecond transient absorption microscopy

DOE PAGES

Xiao, Kai; Ma, Ying -Zhong; Simpson, Mary Jane; ...

2016-04-22

Charge carrier trapping degrades the performance of organometallic halide perovskite solar cells. To characterize the locations of electronic trap states in a heterogeneous photoactive layer, a spatially resolved approach is essential. Here, we report a comparative study on methylammonium lead tri-iodide perovskite thin films subject to different thermal annealing times using a combined photoluminescence (PL) and femtosecond transient absorption microscopy (TAM) approach to spatially map trap states. This approach coregisters the initially populated electronic excited states with the regions that recombine radiatively. Although the TAM images are relatively homogeneous for both samples, the corresponding PL images are highly structured. Themore » remarkable variation in the PL intensities as compared to transient absorption signal amplitude suggests spatially dependent PL quantum efficiency, indicative of trapping events. Furthermore, detailed analysis enables identification of two trapping regimes: a densely packed trapping region and a sparse trapping area that appear as unique spatial features in scaled PL maps.« less

A theoretical study of microwave beam absorption by a Rectenna

NASA Technical Reports Server (NTRS)

Ott, J. H.; Rice, J. S.; Thorn, D. C.

1980-01-01

The results of a theoretical study of microwave beam absorption by a rectenna is given. Total absorption of power beam is shown to be theoretically possible. Several improvements in the rectenna design are indicated as a result of analytic modeling. The nature of rectenna scattering and atmospheric effects is discussed.

A theoretical study of microwave beam absorption by a rectenna

NASA Technical Reports Server (NTRS)

Ott, J. H.; Rice, J. S.; Thorn, D. C.

1981-01-01

The results of a theoretical study of microwave beam absorption by a Rectenna are given. Total absorption of the power beam is shown to be theoretically possible. Several improvements in the Rectenna design are indicated as a result of analytic modeling. The nature of Rectenna scattering and atmospheric effects are discussed.

Intestinal fluid absorption in spontaneously hypertensive rats.

PubMed Central

Dorey, P G; King, J; Munday, K A; Parsons, B J; Poat, J A

1983-01-01

A comparison has been made of intestinal fluid absorption between male Okamoto spontaneously hypertensive rats (s.h.r.) and normotensive male Wistar controls. S.h.r. show enhanced fluid absorption both in hypertensive adults and in young s.h.r. before hypertension has developed. Several potential causes for increased fluid transport in s.h.r. were tested using pharmacological antagonists. It is unlikely that enhanced fluid absorption is due to high sympathetic nervous activity, the renin-angiotensin system or is secondary to hypertension. Intestine from s.h.r. have a high short-circuit current indicating a change in ion pump activity. These results are discussed in relation to the possible causes of increased fluid (ion) transport by the intestine of s.h.r. PMID:6361232

Acetaminophen (paracetamol) oral absorption and clinical influences.

PubMed

Raffa, Robert B; Pergolizzi, Joseph V; Taylor, Robert; Decker, John F; Patrick, Jeffrey T

2014-09-01

Acetaminophen (paracetamol) is a widely used nonopioid, non-NSAID analgesic that is effective against a variety of pain types, but the consequences of overdose can be severe. Because acetaminophen is so widely available as a single agent and is increasingly being formulated in fixed-ratio combination analgesic products for the potential additive or synergistic analgesic effect and/or reduced adverse effects, accidental cumulative overdose is an emergent concern. This has rekindled interest in the sites, processes, and pharmacokinetics of acetaminophen oral absorption and the clinical factors that can influence these. The absorption of oral acetaminophen occurs primarily along the small intestine by passive diffusion. Therefore, the rate-limiting step is the rate of gastric emptying into the intestines. Several clinical factors can affect absorption per se or the rate of gastric emptying, such as diet, concomitant medication, surgery, pregnancy, and others. Although acetaminophen does not have the abuse potential of opioids or the gastrointestinal bleeding or organ adverse effects of NSAIDs, excess amounts can produce serious hepatic injury. Thus, an understanding of the sites and features of acetaminophen absorption--and how they might be influenced by factors encountered in clinical practice--is important for pain management using this agent. It can also provide insight for design of formulations that would be less susceptible to clinical variables. © 2013 World Institute of Pain.

Ultraviolet absorption hygrometer

DOEpatents

Gersh, M.E.; Bien, F.; Bernstein, L.S.

1986-12-09

An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

Electromagnetic-radiation absorption by water.

PubMed

Lunkenheimer, P; Emmert, S; Gulich, R; Köhler, M; Wolf, M; Schwab, M; Loidl, A

2017-12-01

Why does a microwave oven work? How does biological tissue absorb electromagnetic radiation? Astonishingly, we do not have a definite answer to these simple questions because the microscopic processes governing the absorption of electromagnetic waves by water are largely unclarified. This absorption can be quantified by dielectric loss spectra, which reveal a huge peak at a frequency of the exciting electric field of about 20 GHz and a gradual tailing off toward higher frequencies. The microscopic interpretation of such spectra is highly controversial and various superpositions of relaxation and resonance processes ascribed to single-molecule or molecule-cluster motions have been proposed for their analysis. By combining dielectric, microwave, THz, and far-infrared spectroscopy, here we provide nearly continuous temperature-dependent broadband spectra of water. Moreover, we find that corresponding spectra for aqueous solutions reveal the same features as pure water. However, in contrast to the latter, crystallization in these solutions can be avoided by supercooling. As different spectral contributions tend to disentangle at low temperatures, this enables us to deconvolute them when approaching the glass transition under cooling. We find that the overall spectral development, including the 20 GHz feature (employed for microwave heating), closely resembles the behavior known for common supercooled liquids. Thus water's absorption of electromagnetic waves at room temperature is not unusual but very similar to that of glass-forming liquids at elevated temperatures, deep in the low-viscosity liquid regime, and should be interpreted along similar lines.

Electromagnetic-radiation absorption by water

NASA Astrophysics Data System (ADS)

Lunkenheimer, P.; Emmert, S.; Gulich, R.; Köhler, M.; Wolf, M.; Schwab, M.; Loidl, A.

2017-12-01

Why does a microwave oven work? How does biological tissue absorb electromagnetic radiation? Astonishingly, we do not have a definite answer to these simple questions because the microscopic processes governing the absorption of electromagnetic waves by water are largely unclarified. This absorption can be quantified by dielectric loss spectra, which reveal a huge peak at a frequency of the exciting electric field of about 20 GHz and a gradual tailing off toward higher frequencies. The microscopic interpretation of such spectra is highly controversial and various superpositions of relaxation and resonance processes ascribed to single-molecule or molecule-cluster motions have been proposed for their analysis. By combining dielectric, microwave, THz, and far-infrared spectroscopy, here we provide nearly continuous temperature-dependent broadband spectra of water. Moreover, we find that corresponding spectra for aqueous solutions reveal the same features as pure water. However, in contrast to the latter, crystallization in these solutions can be avoided by supercooling. As different spectral contributions tend to disentangle at low temperatures, this enables us to deconvolute them when approaching the glass transition under cooling. We find that the overall spectral development, including the 20 GHz feature (employed for microwave heating), closely resembles the behavior known for common supercooled liquids. Thus water's absorption of electromagnetic waves at room temperature is not unusual but very similar to that of glass-forming liquids at elevated temperatures, deep in the low-viscosity liquid regime, and should be interpreted along similar lines.

Optical absorption in recycled waste plastic polyethylene

NASA Astrophysics Data System (ADS)

Aji, M. P.; Rahmawati, I.; Priyanto, A.; Karunawan, J.; Wati, A. L.; Aryani, N. P.; Susanto; Wibowo, E.; Sulhadi

2018-03-01

We investigated the optical properties of UV spectrum absorption in recycled waste plastic from polyethylene polymer type. Waste plastic polyethylene showed an optical spectrum absorption after it’s recycling process. Spectrum absorption is determined using spectrophotometer UV-Nir Ocean Optics type USB 4000. Recycling method has been processed using heating treatment around the melting point temperature of the polyethylene polymer that are 200°C, 220°C, 240°C, 260°C, and 280°C. In addition, the recycling process was carried out with time variations as well, which are 1h, 1.5h, 2h, and 2.5h. The result of this experiment shows that recycled waste plastic polyethylene has a spectrum absorption in the ∼ 340-550 nm wavelength range. The absorbance spectrum obtained from UV light which is absorbed in the orbital n → π* and the orbital π → π*. This process indicates the existence of electron transition phenomena. This mechanism is affected by the temperature and the heating time where the intensity of absorption increases and widens with the increase of temperature and heating time. Furthermore this study resulted that the higher temperature affected the enhancement of the band gap energy of waste plastic polyethylene. These results show that recycled waste plastic polyethylene has a huge potential to be absorber materials for solar cell.

Dynamic Optoelectronic Properties in Perovskite Oxide Thin Films Measured with Ultrafast Transient Absorption & Reflectance Spectroscopy

NASA Astrophysics Data System (ADS)

Smolin, Sergey Y.

-dependent, variable-angle spectroscopic ellipsometry and time-resolved ultrafast optical spectroscopy on a type I heterostructure, we clarify thermal and electronic contributions to spectral transients in LaFeO3. Upon comparison to thermally-derived static spectra of LaFeO3, we find that thermal contributions dominate the transient absorption and reflectance spectra above the band gap. A transient photoinduced absorption feature below the band gap at 1.9 eV is not reproduced in the thermally derived spectra and has significantly longer decay kinetics from the thermallyinduced features; therefore, this long lived photoinduced absorption is likely derived, at least partially, from photoexcited carriers with lifetimes much longer than 3 nanoseconds. LaFeO3 has a wide band gap of 2.4 eV but its absorption can be decreased with chemical substitution of Sr for Fe to make it more suitable for various applications. This type of A-site substitution is a common route to change static optical absorption in perovskite oxides, but there are no systematic studies looking at how A-site substitution changes dynamic optoelectronic properties. To understand the relationship between composition and static and dynamic optical properties we worked with the model system of La1-xSrxFeO 3-delta epitaxial films grown on LSAT, uncovering the effects of A-site cation substitution and oxygen stoichiometry. Variable-angle spectroscopic ellipsometry was used to measure static optical properties, revealing a linear increase in absorption coefficient at 1.25 eV and a red-shifting of the optical absorption edge with increasing Sr fraction. The absorption spectra can be similarly tuned through the introduction of oxygen vacancies, indicating the critical role that nominal Fe valence plays in optical absorption. Dynamic optoelectronic properties were studied with ultrafast transient reflectance spectroscopy with broadband visible (1.6 eV to 4 eV) and near-infrared (0.9 eV to 1.5 eV) probes. The sign of the reflectance

Gas-phase Absorption of {{\\rm{C}}}_{70}^{2+} below 10 K: Astronomical Implications

NASA Astrophysics Data System (ADS)

Campbell, E. K.; Holz, M.; Maier, J. P.

2017-02-01

The electronic spectrum of the fullerene dication {{{C}}}702+ has been measured in the gas phase at low temperature in a cryogenic radiofrequency ion trap. The spectrum consists of a strong origin band at 7030 Å and two weaker features to higher energy. The bands have FWHMs of 35 Å indicating an excited state lifetime on the order of one-tenth of a picosecond. Absorption cross-section measurements yield (2 ± 1) × 10-15 cm2 at 7030 Å. These results are used to predict the depth of diffuse interstellar bands (DIBs) due to the absorption by {{{C}}}702+. At an assumed column density of 2 × 1012 cm-2 the attenuation of starlight at 7030 Å is around 0.4% and thus the detection of such a shallow and broad interstellar band would be difficult. The electronic spectrum of {{{C}}}602+ shows no absorptions in the visible. Below 4000 Å the spectra of C60, {{{C}}}60+ and {{{C}}}602+ are similar. The large intrinsic FWHM of the features in this region, ˜200 Å for the band near 3250 Å, make them unsuitable for DIB detection.

Hydrolysis Batteries: Generating Electrical Energy during Hydrogen Absorption.

PubMed

Xiao, Rui; Chen, Jun; Fu, Kai; Zheng, Xinyao; Wang, Teng; Zheng, Jie; Li, Xingguo

2018-02-19

The hydrolysis reaction of aluminum can be decoupled into a battery by pairing an Al foil with a Pd-capped yttrium dihydride (YH 2 -Pd) electrode. This hydrolysis battery generates a voltage around 0.45 V and leads to hydrogen absorption into the YH 2 layer. This represents a new hydrogen absorption mechanism featuring electrical energy generation during hydrogen absorption. The hydrolysis battery converts 8-15 % of the thermal energy of the hydrolysis reaction into usable electrical energy, leading to much higher energy efficiency compared to that of direct hydrolysis. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Christiansen effect in disperse systems with resonant absorption

SciTech Connect

Zimnyakov, D A; Isaeva, Elmira A; Isaeva, A A

We discuss the results of experimental studies of competition of absorption and scattering of laser radiation propagating in dispersive media with resonant absorption. As media under study, use is made of a suspension of polystyrene particles in solutions of rhodamine 6G in ethylene glycol probed by laser light with a wavelength of 532 nm. It is found that an increase in the dye concentration leads to an increase in optical transmittance of suspensions and an increase in speckle modulation of the forward-scattered radiation. We interpret these features as a manifestation of Christiansen effect in disperse systems with resonance absorption.

Feature-based Morphometry

PubMed Central

Toews, Matthew; Wells, William M.; Collins, Louis; Arbel, Tal

2013-01-01

This paper presents feature-based morphometry (FBM), a new, fully data-driven technique for identifying group-related differences in volumetric imagery. In contrast to most morphometry methods which assume one-to-one correspondence between all subjects, FBM models images as a collage of distinct, localized image features which may not be present in all subjects. FBM thus explicitly accounts for the case where the same anatomical tissue cannot be reliably identified in all subjects due to disease or anatomical variability. A probabilistic model describes features in terms of their appearance, geometry, and relationship to sub-groups of a population, and is automatically learned from a set of subject images and group labels. Features identified indicate group-related anatomical structure that can potentially be used as disease biomarkers or as a basis for computer-aided diagnosis. Scale-invariant image features are used, which reflect generic, salient patterns in the image. Experiments validate FBM clinically in the analysis of normal (NC) and Alzheimer’s (AD) brain images using the freely available OASIS database. FBM automatically identifies known structural differences between NC and AD subjects in a fully data-driven fashion, and obtains an equal error classification rate of 0.78 on new subjects. PMID:20426102

Spectrophotometry of six broad absorption line QSOs

NASA Technical Reports Server (NTRS)

Junkkarinen, Vesa T.; Burbidge, E. Margaret; Smith, Harding E.

1987-01-01

Spectrophotometric observations of six broad absorption-line QSOs (BALQSOs) are presented. The continua and emission lines are compared with those in the spectra of QSOs without BALs. A statistically significant difference is found in the emission-line intensity ratio for (N V 1240-A)/(C IV 1549-A). The median value of (N V)/(C IV) for the BALQSOs is two to three times the median for QSOs without BALs. The absorption features of the BALQSOs are described, and the column densities and limits on the ionization structure of the BAL region are discussed. If the dominant ionization mechanism is photoionization, then it is likely that either the ionizing spectrum is steep or the abundances are considerably different from solar. Collisional ionization may be a significant factor, but it cannot totally dominate the ionization rate.

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

NASA Astrophysics Data System (ADS)

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.; Leone, Stephen R.

2016-01-01

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicate the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. An intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.

Systematic review: Helicobacter pylori infection and impaired drug absorption.

PubMed

Lahner, E; Annibale, B; Delle Fave, G

2009-02-15

Impaired acid secretion may affect drug absorption and may be consequent to corporal Helicobacter pylori-gastritis, which may affect the absorption of orally administered drugs. To focus on the evidence of impaired drug absorption associated with H. pylori infection. Data sources were the systematic search of MEDLINE/EMBASE/SCOPUS databases (1980-April 2008) for English articles using the keywords: drug malabsorption/absorption, stomach, Helicobacter pylori, gastritis, gastric acid, gastric pH, hypochlorhydria, gastric hypoacidity. Study selection was made from 2099 retrieved articles, five studies were identified. Data were extracted from selected papers, investigated drugs, study type, main features of subjects, study design, intervention type and results were extracted. In all, five studies investigated impaired absorption of l-dopa, thyroxine and delavirdine in H. pylori infection. Eradication treatment led to 21-54% increase in l-dopa in Parkinson's disease. Thyroxine requirement was higher in hypochlorhydric goitre with H. pylori-gastritis and thyrotropin levels decreased by 94% after treatment. In H. pylori- and HIV-positive hypochlorhydric subjects, delavirdine absorption increased by 57% with orange juice administration and by 150% after eradication. A plausible mechanism of impaired drug absorption is decreased acid secretion in H. pylori-gastritis patients. Helicobacter pylori infection and hypochlorhydria should be considered in prescribing drugs the absorption of which is potentially affected by intragastric pH.

MULTIMAGNON ABSORPTION IN MNF2-OPTICAL ABSORPTION SPECTRUM.

DTIC Science & Technology

The absorption spectrum of MnF2 at 4.2K in the 3900A region was measured in zero external fields and in high fields. Exciton lines with magnon ...sidebands are observed, accompanied by a large number of weak satellite lines. Results on the exciton and magnon absorptions are similar to those of...McClure et al. The satellite lines are interpreted as being multi- magnon absorptions, and it is possible to fit the energy of all the absorptions with

Differential optoacoustic absorption detector

NASA Technical Reports Server (NTRS)

Shumate, M. S. (Inventor)

1978-01-01

A differential optoacoustic absorption detector employed two tapered cells in tandem or in parallel. When operated in tandem, two mirrors were used at one end remote from the source of the beam of light directed into one cell back through the other, and a lens to focus the light beam into the one cell at a principal focus half way between the reflecting mirror. Each cell was tapered to conform to the shape of the beam so that the volume of one was the same as for the other, and the volume of each received maximum illumination. The axes of the cells were placed as close to each other as possible in order to connect a differential pressure detector to the cells with connecting passages of minimum length. An alternative arrangement employed a beam splitter and two lenses to operate the cells in parallel.

Triple effect absorption cycles

SciTech Connect

Erickson, D.C.; Potnis, S.V.; Tang, J.

1996-12-31

Triple effect absorption chillers can achieve 50% COP improvement over double-effect systems. However, to translate this potential into cost-effective hardware, the most promising embodiments must be identified. In this study, 12 generic triple effect cycles and 76 possible hermetic loop arrangements of those 12 generic cycles were identified. The generic triple effect cycles were screened based on their pressure and solubility field requirements, generic COPs, risk involved in the component design, and number of components in a high corrosive environment. This screening identified four promising arrangements: Alkitrate Topping cycle, Pressure Staged Envelope cycle, High Pressure Overlap cycle, and Dual Loopmore » cycle. All of these arrangements have a very high COP ({approximately} 1.8), however the development risk and cost involved is different for each arrangement. Therefore, the selection of a particular arrangement will depend upon the specific situation under consideration.« less

Analyzing Water's Optical Absorption

NASA Technical Reports Server (NTRS)

2002-01-01

A cooperative agreement between World Precision Instruments (WPI), Inc., and Stennis Space Center has led the UltraPath(TM) device, which provides a more efficient method for analyzing the optical absorption of water samples at sea. UltraPath is a unique, high-performance absorbance spectrophotometer with user-selectable light path lengths. It is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the laboratory or the field. As a low-cost, rugged, and portable system capable of high- sensitivity measurements in widely divergent waters, UltraPath will help scientists examine the role that coastal ocean environments play in the global carbon cycle. UltraPath(TM) is a trademark of World Precision Instruments, Inc. LWCC(TM) is a trademark of World Precision Instruments, Inc.

Nonequilibrium quantum absorption refrigerator

NASA Astrophysics Data System (ADS)

Du, Jian-Ying; Zhang, Fu-Lin

2018-06-01

We study a quantum absorption refrigerator, in which a target qubit is cooled by two machine qubits in a nonequilibrium steady-state. It is realized by a strong internal coupling in the two-qubit fridge and a vanishing tripartite interaction among the whole system. The coherence of a machine virtual qubit is investigated as quantumness of the fridge. A necessary condition for cooling shows that the quantum coherence is beneficial to the nonequilibrium fridge, while it is detrimental as far as the maximum coefficient of performance (COP) and the COP at maximum power are concerned. Here, the COP is defined only in terms of heat currents caused by the tripartite interaction, with the one maintaining the two-qubit nonequilibrium state being excluded. The later can be considered to have no direct involvement in extracting heat from the target, as it is not affected by the tripartite interaction.

Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.

NASA Astrophysics Data System (ADS)

Marley, N. A.; Marchany-Rivera, A.; Kelley, K. L.; Mangu, A.; Gaffney, J. S.

2007-12-01

Measurements of aerosol absorption were obtained as part of the MAX-Mex component of the MILAGRO field campaign at site T0 (Instituto Mexicano de Petroleo in Mexico City) by using a 7-channel aethalometer (Thermo- Anderson) during the month of March, 2006. The absorption measurements obtained in the field at 370, 470, 520, 590, 660, 880, and 950 nm were used to determine the aerosol Angstrom absorption exponents by linear regression. Since, unlike other absorbing aerosol species (e.g. humic like substances, nitrated PAHs), black carbon absorption is relatively constant from the ultraviolet to the infrared with an Angstrom absorption exponent of -1 (1), a comparison of the Angstrom exponents can indicate the presence of aerosol components with an enhanced UV absorption over that expected from BC content alone. The Angstrom exponents determined from the aerosol absorption measurements obtained in the field varied from - 0.7 to - 1.3 during the study and was generally lower in the afternoon than the morning hours, indicating an increase in secondary aerosol formation and photochemically generated UV absorbing species in the afternoon. Twelve-hour integrated samples of fine atmospheric aerosols (<0.1micron) were also collected at site T0 and T1 (Universidad Technologica de Tecamac, State of Mexico) from 5 am to 5 pm (day) and from 5 pm to 5 am (night) during the month of March 2006. Samples were collected on quartz fiber filters with high volume impactor samplers. Continuous absorption spectra of these aerosol samples have been obtained in the laboratory from 280 to 900nm with the use of an integrating sphere coupled to a UV spectrometer (Beckman DU with a Labsphere accessory). The integrating sphere allows the detector to collect and spatially integrate the total radiant flux reflected from the sample and therefore allows for the measurement of absorption on highly reflective or diffusely scattering samples. These continuous spectra have also been used to obtain the

Health Care Indicators

PubMed Central

Donham, Carolyn S.; Sensenig, Arthur L.

1994-01-01

This regular feature of the journal includes a discussion of each of the following four topics: community hospital statistics; employment, hours, and earnings in the private health sector; health care prices; and national economic indicators. These statistics are valuable in their own right for understanding the relationship between the health care sector and the overall economy. In addition, they allow us to anticipate the direction and magnitude of health care cost changes prior to the availability of more comprehensive data. PMID:10142373

Calcium absorption is not increased by caseinophosphopeptides.

PubMed

Teucher, Birgit; Majsak-Newman, Gosia; Dainty, Jack R; McDonagh, David; FitzGerald, Richard J; Fairweather-Tait, Susan J

2006-07-01

One of the suggested health benefits of caseinophosphopeptides (CPPs) is their ability to enhance calcium absorption. This possibility is based on the assumption that they resist proteolysis in the upper gastrointestinal tract and maintain calcium in a soluble form at alkaline pH in the distal ileum. The effects of CPP-enriched preparations (containing candidate functional food ingredients) on calcium absorption from a calcium lactate drink were tested. A randomized crossover trial was undertaken in 15 adults in whom we measured the absorption of calcium from a calcium lactate drink (drink A: 400 mg Ca as lactate) and 2 preparations enriched with forms of CPP (1.7 g each; drinks B and C). Both drinks B and C contained 400 mg Ca as calcium lactate plus approximately 100 mg CPP-derived calcium). Each volunteer received the 3 drinks in random order. Absorption was measured by the dual-label calcium stable-isotope technique. The quantity of calcium absorbed was significantly lower from drink A (103 mg) than from drink B (117 mg; P = 0.012) or drink C (121 mg; P = 0.002), which indicated a positive effect of the CPPs. However, because the CPP preparations contributed additional calcium besides that found in the calcium lactate (drink A), fractional absorption of calcium from drink B (23%) was slightly but significantly (P = 0.015) lower than that from drink A (26%). The differences in calcium absorption are unlikely to have any biological significance. CPPs are unsuitable as candidate ingredients for functional foods that are designed to deliver improved calcium nutrition.

Detection of metal stress in boreal forest species using the 0.67-micron chlorophyll absorption band

NASA Technical Reports Server (NTRS)

Singhroy, Vernon H.; Kruse, Fred A.

1991-01-01

Several recent studies have shown that a shift of the red-edge inflection near 0.70 micron in vegetation reflectance spectra is an indicator of metal stress, partially attributable to changes in chlorophyll concentration. This 'red-edge shift', however, is difficult to detect and has been reported both toward longer (red) and shorter (blue) wavelengths. Our work demonstrates that direct measurement of the depth and width of the chlorophyll absorption band at 0.67 micron using digital feature extraction and absorption band characterization procedures developed for the analysis of mineral spectra is a more consistent indicator of metal stress. Additionally, the magnitude of these parameters is generally greater than that of the red edge shift and thus should be more amenable to detection and mapping using field and aircraft spectrometers.

Absorption by Spinning Dust: A Contaminant for High-redshift 21 cm Observations

NASA Astrophysics Data System (ADS)

Draine, B. T.; Miralda-Escudé, Jordi

2018-05-01

Spinning dust grains in front of the bright Galactic synchrotron background can produce a weak absorption signal that could affect measurements of high-redshift 21 cm absorption. At frequencies near 80 MHz where the Experiment to Detect the Global EoR Signature (EDGES) has reported 21 cm absorption at z≈ 17, absorption could be produced by interstellar nanoparticles with radii a≈ 50 \\mathringA in the cold interstellar medium (ISM), with rotational temperature T ≈ 50 K. Atmospheric aerosols could contribute additional absorption. The strength of the absorption depends on the abundance of such grains and on their dipole moments, which are uncertain. The breadth of the absorption spectrum of spinning dust limits its possible impact on measurement of a relatively narrow 21 cm absorption feature.

BASIC STUDIES IN PERCUTANEOUS ABSORPTION.

DTIC Science & Technology

FATTY ACIDS, *SKIN(ANATOMY), ABSORPTION, ALKYL RADICALS, AMIDES, DIFFUSION, ELECTRON MICROSCOPY, HUMIDITY, LABORATORY ANIMALS, LIPIDS, ORGANIC SOLVENTS, PENETRATION, PRIVATION, PROTEINS, RATS, TEMPERATURE, WATER

Optical Absorption in Liquid Semiconductors

NASA Astrophysics Data System (ADS)

Bell, Florian Gene

An infrared absorption cell has been developed which is suitable for high temperature liquids which have absorptions in the range .1-10('3) cm('-1). The cell is constructed by clamping a gasket between two flat optical windows. This unique design allows the use of any optical windows chemically compatible with the liquid. The long -wavelength limit of the measurements is therefore limited only by the choice of the optical windows. The thickness of the cell can easily be set during assembly, and can be varied from 50 (mu)m to .5 cm. Measurements of the optical absorption edge were performed on the liquid alloy Se(,1-x)Tl(,x) for x = 0, .001, .002, .003, .005, .007, and .009, from the melting point up to 475(DEGREES)C. The absorption was found to be exponential in the photon energy over the experimental range from 0.3 eV to 1.2 eV. The absorption increased linearly with concentration according to the empirical relation (alpha)(,T)(h(nu)) = (alpha)(,1) + (alpha)(,2)x, and the absorption (alpha)(,1) was interpreted as the absorption in the absence of T1. (alpha)(,1) also agreed with the measured absorption in 100% Se at corresponding temperatures and energies. The excess absorption defined by (DELTA)(alpha) = (alpha)(,T)(h(nu))-(alpha)(,1) was interpreted as the absorption associated with Tl and was found to be thermally activated with an activation energy E(,t) = 0.5 eV. The exponential edge is explained as absorption on atoms immersed in strong electric fields surrounding ions. The strong fields give rise to an absorption tail similar to the Franz-Keldysh effect. A simple calculation is performed which is based on the Dow-Redfield theory of absorption in an electric field with excitonic effects included. The excess absorption at low photon energies is proportional to the square of the concentration of ions, which are proposed to exist in the liquid according to the relation C(,i) (PROPORTIONAL) x(' 1/2)(.)e('-E)t('/kT), which is the origin of the thermal activation

Gas Phase Absorption Spectroscopy of C+60 and C+70 in a Cryogenic Ion Trap: Comparison with Astronomical Measurements

NASA Astrophysics Data System (ADS)

Campbell, E. K.; Holz, M.; Maier, J. P.; Gerlich, D.; Walker, G. A. H.; Bohlender, D.

2016-05-01

Recent low-temperature laboratory measurements and astronomical observations have proved that the fullerene cation {{{C}}}60+ is responsible for four diffuse interstellar bands (DIBs). These absorptions correspond to the strongest bands of the lowest electronic transition. The gas phase spectrum below 10 {{K}} is reported here for the full wavelength range encompassed by the electronic transition. The absorption spectrum of {{{C}}}70+, with its origin band at 7959.2 {{\\mathringA }}, has been obtained under similar laboratory conditions. Observations made toward the reddened star {HD} 183143 were used in a specific search for the absorption of these fullerene cations in diffuse clouds. In the case of {{{C}}}60+, one further band in the astronomical spectrum at 9348.5 \\mathringA is identified, increasing the total number of assigned DIBs to five. Numerous other {{{C}}}60+ absorptions in the laboratory spectrum are found to lie below the astronomical detection limit. Special emphasis is placed on the laboratory determination of absolute absorption cross-sections. For {{{C}}}60+ this directly yields a column density, N({{{C}}}60+), of 2× {10}13 {{{cm}}}-2 in diffuse clouds, without the need to rely on theoretical oscillator strengths. The intensity of the {{{C}}}70+ electronic transition in the range 7000-8000 Å is spread over many features of similar strength. Absorption cross-section measurements indicate that even for a similar column density, the individual absorption bands of {{{C}}}70+ will be too weak to be detected in the astronomical spectra, which is confirmed giving an upper limit of 2 {{m\\mathringA }} to the equivalent width. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

THE VIEWING ANGLES OF BROAD ABSORPTION LINE VERSUS UNABSORBED QUASARS

SciTech Connect

DiPompeo, M. A.; Brotherton, M. S.; De Breuck, C.

2012-06-10

It was recently shown that there is a significant difference in the radio spectral index distributions of broad absorption line (BAL) quasars and unabsorbed quasars, with an overabundance of BAL quasars with steeper radio spectra. This result suggests that source orientation does play into the presence or absence of BAL features. In this paper, we provide more quantitative analysis of this result based on Monte Carlo simulations. While the relationship between viewing angle and spectral index does indeed contain a lot of scatter, the spectral index distributions are different enough to overcome that intrinsic variation. Utilizing two different models ofmore » the relationship between spectral index and viewing angle, the simulations indicate that the difference in spectral index distributions can be explained by allowing BAL quasar viewing angles to extend about 10 Degree-Sign farther from the radio jet axis than non-BAL sources, though both can be seen at small angles. These results show that orientation cannot be the only factor determining whether BAL features are present, but it does play a role.« less

Gas in scattering media absorption spectroscopy - GASMAS

NASA Astrophysics Data System (ADS)

Svanberg, Sune

2008-09-01

An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. GASMAS combines narrow-band diode-laser spectroscopy with diffuse media optical propagation. While solids and liquids have broad absorption features, free gas in pores and cavities in the material is characterized by sharp spectral signatures, typically 10,000 times sharper than those of the host material. Many applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, allowing propagation. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities have been studied. Transport of gas in porous media can readily be studied by first immersing the material in, e.g., pure nitrogen, and then observing the rate at which normal air, containing oxygen, reinvades the material. The conductance of the sinus connective passages can be measured in this way by flushing the nasal cavity with nitrogen. Also other dynamic processes such as drying of materials can be studied. The techniques have also been extended to remote-sensing applications (LIDAR-GASMAS).

Differential-optoacoustic absorption detector

NASA Technical Reports Server (NTRS)

Shumate, M. S.

1977-01-01

Two-cell spectrophone detects trace amounts of atmospheric pollutants by measuring absorption coefficients of gases with various laser sources. Device measures pressure difference between two tapered cells with differential manometer. Background signal is reduced by balanced window heating and balanced carrier gas absorption in two cells.

Atmospheric absorption of sound - Update

NASA Technical Reports Server (NTRS)

Bass, H. E.; Sutherland, L. C.; Zuckerwar, A. J.

1990-01-01

Best current expressions for the vibrational relaxation times of oxygen and nitrogen in the atmosphere are used to compute total absorption. The resulting graphs of total absorption as a function of frequency for different humidities should be used in lieu of the graph published earlier by Evans et al (1972).

Online feature selection with streaming features.

PubMed

Wu, Xindong; Yu, Kui; Ding, Wei; Wang, Hao; Zhu, Xingquan

2013-05-01

We propose a new online feature selection framework for applications with streaming features where the knowledge of the full feature space is unknown in advance. We define streaming features as features that flow in one by one over time whereas the number of training examples remains fixed. This is in contrast with traditional online learning methods that only deal with sequentially added observations, with little attention being paid to streaming features. The critical challenges for Online Streaming Feature Selection (OSFS) include 1) the continuous growth of feature volumes over time, 2) a large feature space, possibly of unknown or infinite size, and 3) the unavailability of the entire feature set before learning starts. In the paper, we present a novel Online Streaming Feature Selection method to select strongly relevant and nonredundant features on the fly. An efficient Fast-OSFS algorithm is proposed to improve feature selection performance. The proposed algorithms are evaluated extensively on high-dimensional datasets and also with a real-world case study on impact crater detection. Experimental results demonstrate that the algorithms achieve better compactness and higher prediction accuracy than existing streaming feature selection algorithms.

Absorption and emission spectra of Li atoms trapped in rare gas matrices

NASA Astrophysics Data System (ADS)

Wright, J. J.; Balling, L. C.

1980-10-01

Pulsed-dye-laser excitation has been used to investigate the optical absorption and emission spectra of Li atoms trapped in Ar, Kr, and Xe matrices at 10 °K. Attempts to stabilize Li atoms in a Ne matrix at 2 °K were unsuccessful. Results for all three rare gases were qualitatively the same. White light absorption scans showed a single absorption with three peaks centered near the free-atom 2s→2p transition wavelength. The intensity of fluorescence produced by dye-laser excitation within this absorption band was measured as a function of emission wavelength. Excitation of the longest- and shortest-wavelength absorption peaks produced identical emission profiles, but no distinct fluorescence signal was detected when the laser was tuned to the central absorption peaks, indicating that the apparent absorption triplet is actually the superposition of a singlet and a doublet absorption originating from two different trapping sites. No additional absorption bands were detected.

Generalized Landauer equation: Absorption-controlled diffusion processes

NASA Astrophysics Data System (ADS)

Godoy, Salvador; García-Colín, L. S.; Micenmacher, Victor

1999-05-01

The exact expression of the one-dimensional Boltzmann multiple-scattering coefficients, for the passage of particles through a slab of a given material, is obtained in terms of the single-scattering cross section of the material, including absorption. The remarkable feature of the result is that for multiple scattering in a metal, free from absorption, one recovers the well-known Landauer result for conduction electrons. In the case of particles, such as neutrons, moving through a weak absorbing media, Landuer's formula is modified due to the absorption cross section. For photons, in a strong absorbing media, one recovers the Lambert-Beer equation. In this latter case one may therefore speak of absorption-controlled diffusive processes.

Interpreting the 10 micron Astronomical Silicate Feature

NASA Astrophysics Data System (ADS)

Bowey, Janet E.

1998-11-01

10micron spectra of silicate dust in the diffuse medium towards Cyg OB2 no. 12 and towards field and embedded objects in the Taurus Molecular Cloud (TMC) were obtained with CGS3 at the United Kingdom Infrared Telescope (UKIRT). Cold molecular-cloud silicates are sampled in quiescent lines of sight towards the field stars Taurus-Elias 16 and Elias 13, whilst observations of the embedded young stellar objects HL Tau, Taurus-Elias 7 (Haro6-10) and Elias 18 also include emission from heated dust. To obtain the foreground silicate absorption profiles, featureless continua are estimated using smoothed astronomical and laboratory silicate emissivities. TMC field stars and Cyg OB2 no. 12 are modelled as photospheres reddened by foreground continuum and silicate extinction. Dust emission in the non-photospheric continua of HL Tau and Elias 7 (Haro6-10) is distinguished from foreground silicate absorption using a 10micron disk model, based on the IR-submm model of T Tauri stars by Adams, Lada & Shu (1988), with terms added to represent the foreground continuum and silicate extinction. The absorption profiles of HL Tau and Elias 7 are similar to that of the field star Elias 16. Fitted temperature indices of 0.43 (HL Tau) and 0.33 (Elias 7) agree with Boss' (1996) theoretical models of the 200-300K region, but are lower than those of IR-submm disks (0.5-0.61; Mannings & Emerson 1994); the modelled 10micron emission of HL Tau is optically thin, that of Elias 7 is optically thick. A preliminary arcsecond-resolution determination of the 10micron emissivity near θ1 Ori D in the Trapezium region of Orion and a range of emission temperatures (225-310K) are derived from observations by T. L. Hayward; this Ney-Allen emissivity is 0.6micron narrower than the Trapezium emissivity obtained by Forrest et al. (1975) with a large aperture. Published interstellar grain models, elemental abundances and laboratory studies of Solar System silicates (IDPs, GEMS and meteorites), the 10micron

Ultraviolet absorption spectrum of HOCl

NASA Technical Reports Server (NTRS)

Burkholder, James B.

1993-01-01

The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

Electrically tunable coherent optical absorption in graphene with ion gel.

PubMed

Thareja, Vrinda; Kang, Ju-Hyung; Yuan, Hongtao; Milaninia, Kaveh M; Hwang, Harold Y; Cui, Yi; Kik, Pieter G; Brongersma, Mark L

2015-03-11

We demonstrate electrical control over coherent optical absorption in a graphene-based Salisbury screen consisting of a single layer of graphene placed in close proximity to a gold back reflector. The screen was designed to enhance light absorption at a target wavelength of 3.2 μm by using a 600 nm-thick, nonabsorbing silica spacer layer. An ionic gel layer placed on top of the screen was used to electrically gate the charge density in the graphene layer. Spectroscopic reflectance measurements were performed in situ as a function of gate bias. The changes in the reflectance spectra were analyzed using a Fresnel based transfer matrix model in which graphene was treated as an infinitesimally thin sheet with a conductivity given by the Kubo formula. The analysis reveals that a careful choice of the ionic gel layer thickness can lead to optical absorption enhancements of up to 5.5 times for the Salisbury screen compared to a suspended sheet of graphene. In addition to these absorption enhancements, we demonstrate very large electrically induced changes in the optical absorption of graphene of ∼3.3% per volt, the highest attained so far in a device that features an atomically thick active layer. This is attributable in part to the more effective gating achieved with the ion gel over the conventional dielectric back gates and partially by achieving a desirable coherent absorption effect linked to the presence of the thin ion gel that boosts the absorption by 40%.

Update: The Digestion and Absorption of Carbohydrate and Protein: Role of the Small Intestine.

ERIC Educational Resources Information Center

Leese, H. J.

1984-01-01

Discusses the role of the small intestine in the digestion and absorption of carbohydrates and proteins. Indicates as outdated the view that these materials must be broken down to monomeric units before absorption and that the gut secretes a mixture of digestive juices which brings about absorption. (JN)

Gas-absorption process

DOEpatents

Stephenson, Michael J.; Eby, Robert S.

1978-01-01

This invention is an improved gas-absorption process for the recovery of a desired component from a feed-gas mixture containing the same. In the preferred form of the invention, the process operations are conducted in a closed-loop system including a gas-liquid contacting column having upper, intermediate, and lower contacting zones. A liquid absorbent for the desired component is circulated through the loop, being passed downwardly through the column, regenerated, withdrawn from a reboiler, and then recycled to the column. A novel technique is employed to concentrate the desired component in a narrow section of the intermediate zone. This technique comprises maintaining the temperature of the liquid-phase input to the intermediate zone at a sufficiently lower value than that of the gas-phase input to the zone to effect condensation of a major part of the absorbent-vapor upflow to the section. This establishes a steep temperature gradient in the section. The stripping factors below this section are selected to ensure that virtually all of the gases in the downflowing absorbent from the section are desorbed. The stripping factors above the section are selected to ensure re-dissolution of the desired component but not the less-soluble diluent gases. As a result, a peak concentration of the desired component is established in the section, and gas rich in that component can be withdrawn therefrom. The new process provides important advantages. The chief advantage is that the process operations can be conducted in a single column in which the contacting zones operate at essentially the same pressure.

The effects of wheelchair-seating stiffness and energy absorption on occupant frontal impact kinematics and submarining risk using computer simulation.

PubMed

Bertocci, Gina; Souza, Aaron L; Szobota, Stephanie

2003-01-01

Many wheelchair users must travel in motor vehicles while seated in their wheelchairs. The safety features of seat assemblies are key to motor vehicle occupant crash protection. Seating system properties such as strength, stiffness, and energy absorbance have been shown to have significant influence on risk of submarining. This study investigated the effects of wheelchair seat stiffness and energy absorption properties on occupant risk of submarining during a frontal motor vehicle 20 g/30 mph impact using a validated computer crash simulation model. The results indicate that wheelchair-seating stiffness and energy absorption characteristics influence occupant kinematics associated with the risk of submarining. Softer seat surfaces and relatively high energy absorption/permanent deformation were found to produce pelvis excursion trajectories associated with increased submarining risk. Findings also suggest that the current American National Standards Institute/Rehabilitation Engineering and Assistive Technology Society of North America (ANSI/RESNA) WC-19 seating integrity may not adequately assess submarining risk.

Identifying significant environmental features using feature recognition.

DOT National Transportation Integrated Search

2015-10-01

The Department of Environmental Analysis at the Kentucky Transportation Cabinet has expressed an interest in feature-recognition capability because it may help analysts identify environmentally sensitive features in the landscape, : including those r...

Gastrointestinal citrate absorption in nephrolithiasis

NASA Technical Reports Server (NTRS)

Fegan, J.; Khan, R.; Poindexter, J.; Pak, C. Y.

1992-01-01

Gastrointestinal absorption of citrate was measured in stone patients with idiopathic hypocitraturia to determine if citrate malabsorption could account for low urinary citrate. Citrate absorption was measured directly from recovery of orally administered potassium citrate (40 mEq.) in the intestinal lavage fluid, using an intestinal washout technique. In 7 stone patients citrate absorption, serum citrate levels, peak citrate concentration in serum and area under the curve were not significantly different from those of 7 normal subjects. Citrate absorption was rapid and efficient in both groups, with 96 to 98% absorbed within 3 hours. The absorption of citrate was less efficient from a tablet preparation of potassium citrate than from a liquid preparation, probably due to a delayed release of citrate from wax matrix. However, citrate absorption from solid potassium citrate was still high at 91%, compared to 98% for a liquid preparation. Thus, hypocitraturia is unlikely to be due to an impaired gastrointestinal absorption of citrate in stone patients without overt bowel disease.

Health indicators 1991.

PubMed

Dawson, N

1991-01-01

This is the second edition of a database developed by the Canadian Centre for Health Information (CCHI). It features 49 health indicators, under one cover containing the most recent data available from a variety of national surveys. This information may be used to establish health goals for the population and to offer objective measures of their success. The database can be accessed through CANSIM, Statistics Canada's socio-economic electronic database and retrieval system, or through a personal computer package which enables the user to retrieve and analyze the 1.2 million data points in the system.

Variable Sodium Absorption in a Low-extinction Type Ia Supernova

NASA Astrophysics Data System (ADS)

Simon, Joshua D.; Gal-Yam, Avishay; Gnat, Orly; Quimby, Robert M.; Ganeshalingam, Mohan; Silverman, Jeffrey M.; Blondin, Stephane; Li, Weidong; Filippenko, Alexei V.; Wheeler, J. Craig; Kirshner, Robert P.; Patat, Ferdinando; Nugent, Peter; Foley, Ryan J.; Vogt, Steven S.; Butler, R. Paul; Peek, Kathryn M. G.; Rosolowsky, Erik; Herczeg, Gregory J.; Sauer, Daniel N.; Mazzali, Paolo A.

2009-09-01

Recent observations have revealed that some Type Ia supernovae exhibit narrow, time-variable Na I D absorption features. The origin of the absorbing material is controversial, but it may suggest the presence of circumstellar gas in the progenitor system prior to the explosion, with significant implications for the nature of the supernova (SN) progenitors. We present the third detection of such variable absorption, based on six epochs of high-resolution spectroscopy of the Type Ia supernova SN 2007le from the Keck I Telescope and the Hobby-Eberly Telescope. The data span a time frame of approximately three months, from 5 days before maximum light to 90 days after maximum. We find that one component of the Na I D absorption lines strengthened significantly with time, indicating a total column density increase of ~2.5 × 1012 cm-2. The data limit the typical timescale for the variability to be more than 2 days but less than 10 days. The changes appear to be most prominent after maximum light rather than at earlier times when the ultraviolet flux from the SN peaks. As with SN 2006X, we detect no change in the Ca II H and K absorption lines over the same time period, rendering line-of-sight effects improbable and suggesting a circumstellar origin for the absorbing material. Unlike the previous two supernovae exhibiting variable absorption, SN 2007le is not highly reddened (E B - V = 0.27 mag), also pointing toward circumstellar rather than interstellar absorption. Photoionization calculations show that the data are consistent with a dense (107 cm-3) cloud or clouds of gas located ~0.1 pc (3 × 1017 cm) from the explosion. These results broadly support the single-degenerate scenario previously proposed to explain the variable absorption, with mass loss from a nondegenerate companion star responsible for providing the circumstellar gas. We also present possible evidence for narrow Hα emission associated with the SN, which will require deep imaging and spectroscopy at

Constraining the Intergalactic and Circumgalactic Media with Lyman-Alpha Absorption

NASA Astrophysics Data System (ADS)

Sorini, Daniele; Onorbe, Jose; Hennawi, Joseph F.; Lukic, Zarija

2018-01-01

Lyman-alpha (Ly-a) absorption features detected in quasar spectra in the redshift range 0absorption in the IGM with large N-body cosmological simulations. The technique developed is more accurate than previous attempts in the literature, and can be applied to Gpc-scale N-body simulations, allowing an accurate investigation of the Ly-a absorption on unprecedentedly large scales. In the second part of my thesis, I compare predictions of state-of-the-art hydrodynamic cosmological simulations with observations of the mean Ly-a absorption around foreground quasars, damped Ly-a absorbers, and Lyman-break galaxies, at different transverse distances (~20kpc-20Mpc) from background quasars. Far from galaxies >2Mpc, the simulations asymptotically match the observations, because the ΛCDM model successfully describes the ambient IGM. This represents a critical advantage of studying the mean absorption profile. However, significant differences between the simulations, and between simulations and observations are present on scales 20kpc-2Mpc, illustrating the challenges of accurately modeling and resolving galaxy formation physics. It is noteworthy that these differences are observed as far out as ~2Mpc, indicating that the `sphere-of-influence' of galaxies could extend to approximately ~20 times the halo virial radius (~100kpc). Current observations are very precise on these scales and can thus strongly discriminate between different galaxy formation models. I demonstrate that the Ly-a absorption profile is primarily sensitive to the underlying temperature-density relationship of diffuse gas around galaxies, and argue that it

Novel transmucosal absorption enhancers obtained by aminoalkylation of chitosan.

PubMed

Zambito, Ylenia; Uccello-Barretta, Gloria; Zaino, Chiara; Balzano, Federica; Di Colo, Giacomo

2006-12-01

Literature data suggest that quaternized chitosans have a transmucosal drug absorption enhancing property depending on their MW, quaternization degree and other structural features. With the purpose of preparing novel effective promoters, a chitosan (Ch) from crab shell (ChC; viscometric MW, 800 kDa; deacetylation: 90%, IR; 84%, NMR) and one from shrimp shell (ChS; viscometric MW, 590 kDa; deacetylation: 90%, IR; 82%, NMR) were reacted with 2-diethylaminoethyl chloride (DEAE-Cl) and novel derivatives containing different percentages of pendant quaternary ammonium groups were obtained. NMR analysis, based on HSQC, COSY, TOCSY and ROESY maps, indicated that three partially substituted N,O-[N,N-diethylaminomethyl(diethyldimethylene ammonium)(n)]methyl chitosans, coded N(+)-ChS-2 (degree of substitution, DS=40%; n=1.6), N(+)-ChS-4 (DS=132%; n=2.5), and N(+)-ChC-4 (DS=85%; n=1.7) resulted from the reaction, depending on whether the DEAE-Cl/Ch repeating unit molar ratio, was 2:1 or 4:1. The effects of the derivatives on the permeability of rhodamine 123 (Rh-123), hydrophobic, marker of the transcellular absorption route, and of fluorescein sodium (NaFlu), polar, marker of the paracellular route, across excised porcine cheek epithelium were assessed, using Franz type diffusion cells. Rh-123 permeability was enhanced by N(+)-ChS-4 (enhancement ratio, ER=8.4) and by N(+)-ChC-4 (ER=3.9), whereas N(+)-ChS-2 was ineffective. NaFlu permeability was enhanced by N(+)-ChS-2 (ER=7.2), N(+)-ChS-4 (ER=7.4) and N(+)-ChC-4 (ER=6.6). In conclusion, the three derivatives, whichever their DS, promote paracellular transport, while transcellular transport is substantially accelerated only by the most substituted one.

A Statistical Study of the Southern Fermi Bubble in UV Absorption Spectra

NASA Astrophysics Data System (ADS)

Karim, Md. Tanveer; Fox, Andrew; Jenkins, Edward; Bordoloi, Rongmon; Wakker, Bart; Savage, Blair D.; Lockman, Felix; Crawford, Steve; Bland-Hawthorn, Joss; Jorgenson, Regina A.

2018-01-01

The Fermi Bubbles are two giant lobes of plasma situated at the center of the Milky Way, extending 55° above and below the Galactic Midplane. Although the Bubbles have been widely studied in multiple wavelengths, few studies have been done in UV absorption. Here we present a statistical study of the Southern Fermi Bubble using 17 QSO sightlines — 6 inside the Bubble, 11 outside — using UV absorption spectra from the Hubble Space Telescope Cosmic Origins Spectrograph (HST/COS). We searched for high-velocity clouds (HVCs) in 11 metal lines from ions of Aluminium, Carbon and Silicon. We detected HVCs in 83% of the sightlines inside the Bubble and 64% outside the Bubble, showing an enhancement in the covering fraction of HVCs in the Southern Bubble region. We also observed a decrease in vLSR of the HVCs as a function of the galactic latitude, consistent with a scenario where the identified HVCs trace the Galactic nuclear outflow, as sightlines closer to the central engine are expected to show a higher velocity. Combined with previous studies, our analysis indicates that the Southern Fermi Bubble is a dynamic environment giving rise to complex absorption features.

SimBAL: A Spectral Synthesis Approach to Analyzing Broad Absorption Line Quasar Spectra

NASA Astrophysics Data System (ADS)

Terndrup, Donald M.; Leighly, Karen; Gallagher, Sarah; Richards, Gordon T.

2017-01-01

Broad Absorption Line quasars (BALQSOs) show blueshifted absorption lines in their rest-UV spectra, indicating powerful winds emerging from the central engine. These winds are essential part of quasars: they can carry away angular momentum and thus facilitate accretion through a disk, they can distribute chemically-enriched gas through the intergalactic medium, and they may inject kinetic energy to the host galaxy, influencing its evolution. The traditional method of analyzing BALQSO spectra involves measuring myriad absorption lines, computing the inferred ionic column densities in each feature, and comparing with the output of photonionization models. This method is inefficient and does not handle line blending well. We introduce SimBAL, a spectral synthesis fitting method for BALQSOs, which compares synthetic spectra created from photoionization model results with continuum-normalized observed spectra using Bayesian model calibration. We find that we can obtain an excellent fit to the UV to near-IR spectrum of the low-redshift BALQSO SDSS J0850+4451, including lines from diverse ionization states such as PV, CIII*, SIII, Lyalpha, NV, SiIV, CIV, MgII, and HeI*.

Indications of the Mineralogy of Callisto and Mars from Reflectance Spectroscopy.

NASA Astrophysics Data System (ADS)

Calvin, Wendy Marie

1991-02-01

Remotely sensed reflectance spectra contain information on mineral identities, grain sizes, and abundances. This thesis consists of analysis of such spectra for two planetary objects, Callisto and Mars. Theoretical modeling of telescopic spectra of Callisto indicates that the surface consists of 20 to 45 wt% water ice at large grain sizes. In the spectral region beyond 3 μm absorption by hydrated mineral phases is dominant. The non-ice material is spectrally similar to hydrous alteration minerals that are commonly found in certain petrologic types of meteorites. New high-resolution data of Callisto are consistent with the findings of the modeling study. In addition, these new data have identified the presence of a small amount of fine-grained water ice on the leading hemisphere, through a characteristic absorption near 3.4 mum. Variations in the depth of this absorption feature indicate dynamic competition between processes which create and erode fine -grained water ice. Calibration and analysis of spectrometer data from the Mariner 6 and 7 space-craft has provided new information regarding the mineralogy of Mars. Laboratory measurements and theoretical calculations of CO_2 frosts have allowed an analysis of spectra taken over the martian south polar cap. The grain sizes in the seasonal cap are quite large and there may be evidence of contamination by water frost or dust. Analysis of Mariner spectra in non-polar regions have tentatively identified absorption features near 2.76 μm and 5.4 mum. The location of these features, and other absorptions identified from terrestrial observations, are consistent with the spectra of hydrous magnesium carbonates. The hydrous carbonates do not have strong spectral features typically associated with carbonates. Theoretical calculations of mixtures indicates that 10-30wt% of these minerals can be included and still be consistent with spectral observations. These minerals form on earth through weathering of mafic minerals with

Broad Absorption Line Quasar catalogues with Supervised Neural Networks

SciTech Connect

Scaringi, Simone; Knigge, Christian; Cottis, Christopher E.

2008-12-05

We have applied a Learning Vector Quantization (LVQ) algorithm to SDSS DR5 quasar spectra in order to create a large catalogue of broad absorption line quasars (BALQSOs). We first discuss the problems with BALQSO catalogues constructed using the conventional balnicity and/or absorption indices (BI and AI), and then describe the supervised LVQ network we have trained to recognise BALQSOs. The resulting BALQSO catalogue should be substantially more robust and complete than BI-or AI-based ones.

On the state of the emitter of the 3.3 micron unidentified infrared band - Absorption spectroscopy of polycyclic aromatic hydrocarbon species

NASA Technical Reports Server (NTRS)

Flickinger, Gregory C.; Wdowiak, Thomas J.; Gomez, Percy L.

1991-01-01

Results of absorption measurements indicate that the PAH species responsible for the UIR (unidentified infrared) emission probably exist in a condensed form rather than as isolated molecules. It is shown that the peak absorption of the C-H stretch feature of vapor-phase PAHs occurs at a higher frequency than that of the condensed-phase PAHs and does not match the 3.289-micron interstellar feature. The vapor-phase experiments duplicate the phenomenon of the 3.3-micron profile simplification of PAH in KBr at elevated temperature. This confirms that the change of the profile with temperature is an intrinsic molecular effect, and is not a consequence of matrix (KBr) or condensed state interactions.

Measurement of Electronic States of PbS Nanocrystal Quantum Dots Using Scanning Tunneling Spectroscopy: The Role of Parity Selection Rules in Optical Absorption

NASA Astrophysics Data System (ADS)

Diaconescu, Bogdan; Padilha, Lazaro A.; Nagpal, Prashant; Swartzentruber, Brian S.; Klimov, Victor I.

2013-03-01

We study the structure of electronic states in individual PbS nanocrystal quantum dots by scanning tunneling spectroscopy (STS) using one-to-two monolayer nanocrystal films treated with 1, 2-ethanedithiols (EDT). Up to six individual valence and conduction band states are resolved for a range of quantum dot sizes. The measured states’ energies are in good agreement with calculations using the k·p four-band envelope function formalism. A comparison of STS and optical absorption spectra indicates that some of the absorption features can only be explained by asymmetric transitions involving the states of different symmetries (e.g., S and P or P and D), which points towards the relaxation of the parity selection rules in these nanostructures. STS measurements also reveal a midgap feature, which is likely similar to one observed in previous charge transport studies of EDT-treated quantum dot films.

Extreme Variability in a Broad Absorption Line Quasar

SciTech Connect

Stern, Daniel; Jun, Hyunsung D.; Graham, Matthew J.

CRTS J084133.15+200525.8 is an optically bright quasar at z = 2.345 that has shown extreme spectral variability over the past decade. Photometrically, the source had a visual magnitude of V ∼ 17.3 between 2002 and 2008. Then, over the following five years, the source slowly brightened by approximately one magnitude, to V ∼ 16.2. Only ∼1 in 10,000 quasars show such extreme variability, as quantified by the extreme parameters derived for this quasar assuming a damped random walk model. A combination of archival and newly acquired spectra reveal the source to be an iron low-ionization broad absorption line quasar withmore » extreme changes in its absorption spectrum. Some absorption features completely disappear over the 9 years of optical spectra, while other features remain essentially unchanged. We report the first definitive redshift for this source, based on the detection of broad H α in a Keck/MOSFIRE spectrum. Absorption systems separated by several 1000 km s{sup −1} in velocity show coordinated weakening in the depths of their troughs as the continuum flux increases. We interpret the broad absorption line variability to be due to changes in photoionization, rather than due to motion of material along our line of sight. This source highlights one sort of rare transition object that astronomy will now be finding through dedicated time-domain surveys.« less

Using Methane Absorption to Probe Jupiter's Atmosphere

NASA Technical Reports Server (NTRS)

1997-01-01

Mosaics of a belt-zone boundary near Jupiter's equator in near-infrared light moderately absorbed by atmospheric methane (top panel), and strongly absorbed by atmospheric methane (bottom panel). The four images that make up each of these mosaics were taken within a few minutes of each other. Methane in Jupiter's atmosphere absorbs light at specific wavelengths called absorption bands. By detecting light close and far from these absorption bands, Galileo can probe to different depths in Jupiter's atmosphere. Sunlight near 732 nanometers (top panel) is moderately absorbed by methane. Some of the light reflected from clouds deep in Jupiter's troposphere is absorbed, enhancing the higher features. Sunlight at 886 nanometers (bottom panel) is strongly absorbed by methane. Most of the light reflected from the deeper clouds is absorbed, making these clouds invisible. Features in the diffuse cloud layer higher in Jupiter's atmosphere are greatly enhanced.

North is at the top. The mosaic covers latitudes -13 to +3 degrees and is centered at longitude 282 degrees West. The smallest resolved features are tens of kilometers in size. These images were taken on November 5th, 1996, at a range of 1.2 million kilometers by the Solid State Imaging system aboard NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

The coupled effect of fiber volume fraction and void fraction on hydraulic fluid absorption of quartz/BMI laminates

NASA Astrophysics Data System (ADS)

Hurdelbrink, Keith R.; Anderson, Jacob P.; Siddique, Zahed; Altan, M. Cengiz

2016-03-01

Bismaleimide (BMI) resin with quartz (AQ581) fiber reinforcement is a composite material frequently used in aerospace applications, such as engine cowlings and radomes. Various composite components used in aircrafts are exposed to different types of hydraulic fluids, which may lead to anomalous absorption behavior over the service life of the composite. Accurate predictive models for absorption of liquid penetrants are particularly important as the composite components are often exposed to long-term degradation due to absorbed moisture, hydraulic fluids, or similar liquid penetrants. Microstructural features such as fiber volume fraction and void fraction can have a significant effect on the absorption behavior of fiber-reinforced composites. In this paper, hydraulic fluid absorption characteristics of quartz/BMI laminates fabricated from prepregs preconditioned at different relative humidity and subsequently cured at different pressures are presented. The composite samples are immersed into hydraulic fluid at room temperature, and were not subjected to any prior degradation. To generate process-induced microvoids, prepregs were conditioned in an environmental chamber at 2% or 99% relative humidity at room temperature for a period of 24 hours prior to laminate fabrication. To alter the fiber volume fraction, the laminates were fabricated at cure pressures of 68.9 kPa (10 psi) or 482.6 kPa (70 psi) via a hot-press. The laminates are shown to have different levels of microvoids and fiber volume fractions, which were observed to affect the absorption dynamics considerably and exhibited clear non-Fickian behavior. A one-dimensional hindered diffusion model (HDM) was shown to be successful in predicting the hydraulic fluid absorption. Model prediction indicates that as the fabrication pressure increased from 68.9 kPa to 482.6 kPa, the maximum fluid content (M∞) decreased from 8.0% wt. to 1.0% wt. The degree of non-Fickian behavior, measured by hindrance coefficient (�

Broadband absorption with gradient metasurfaces

NASA Astrophysics Data System (ADS)

Kwon, Hoyeong; Chalabi, Hamidreza; Alù, Andrea

2018-03-01

A metasurface with appropriately designed transverse spatial inhomogeneities can provide the desired phase redistribution in response to an incident wave with arbitrary incident angle. This property of gradient metasurfaces has been used to modify light propagation in unusual manners, to transform the impinging optical wavefront with large flexibility. In this work, we show how gradient metasurfaces can be tailored to offer high absorption in thin absorptive layers, and how to design realistic metasurfaces for this purpose using dielectric materials.

Reduced chromium in olivine grains from lunar basalt 15555 - X-ray Absorption Near Edge Structure (XANES)

NASA Technical Reports Server (NTRS)

Sutton, S. R.; Jones, K. W.; Gordon, B.; Rivers, M. L.; Bajt, S.; Smith, J. V.

1993-01-01

The oxidation state of Cr in 200-micron regions within individual lunar olivine and pyroxene grains from lunar basalt 15555 was inferred using X-ray Absorption Near Edge Structure (XANES). Reference materials had previously been studied by optical absorption spectroscopy and included Cr-bearing borosilicate glasses synthesized under controlled oxygen fugacity and Cr-doped olivines. The energy dependence of XANES spectral features defined by these reference materials indicated that Cr is predominantly divalent in the lunar olivine and trivalent in the pyroxene. These results, coupled with the apparent f(02)-independence of partitioning coefficients for Cr into olivine, imply that the source magma was dominated by divalent Cr at the time of olivine crystallization.

Scramjet Performance Assessment Using Water Absorption Diagnostics (U)

NASA Technical Reports Server (NTRS)

Cavolowsky, John A.; Loomis, Mark P.; Deiwert, George

1995-01-01

Simultaneous multiple path measurements of temperature and H2O concentration will be presented for the AIMHYE test entries in the NASA Ames 16-Inch Shock Tunnel. Monitoring the progress of high temperature chemical reactions that define scramjet combustor efficiencies is a task uniquely suited to nonintrusive optical diagnostics. One application strategy to overcome the many challenges and limitations of nonintrusive measurements is to use laser absorption spectroscopy coupled with optical fibers. Absorption spectroscopic techniques with rapidly tunable lasers are capable of making simultaneous measurements of mole fraction, temperature, pressure, and velocity. The scramjet water absorption diagnostic was used to measure combustor efficiency and was compared to thrust measurements using a nozzle force balance and integrated nozzle pressures to develop a direct technique for evaluating integrated scramjet performance. Tests were initially performed with a diode laser tuning over a water absorption feature at 1391.7 nm. A second diode laser later became available at a wavelength near 1343.3 nm covering an additional water absorption feature and was incorporated in the system for a two-wavelength technique. Both temperature and mole fraction can be inferred from the lineshape analysis using this approach. Additional high temperature spectroscopy research was conducted to reduce uncertainties in the scramjet application. The lasers are optical fiber coupled to ports at the combustor exit and in the nozzle region. The output from the two diode lasers were combined in a single fiber, and the resultant two-wavelength beam was subsequently split into four legs. Each leg was directed through 60 meters of optical fiber to four combustor exit locations for measurement of beam intensity after absorption by the water within the flow. Absorption results will be compared to 1D combustor analysis using RJPA and nozzle CFD computations as well as to data from a nozzle metric

Modeling the Oxygen K Absorption in the Interstellar Medium: An XMM-Newton View of Sco X-1

NASA Technical Reports Server (NTRS)

Garcia, J.; Ramirez, J. M.; Kallman, T. R.; Witthoeft, M.; Bautista, M. A.; Mendoza, C.; Palmeri, P.; Quinet, P.

2011-01-01

We investigate the absorption structure of the oxygen in the interstellar medium by analyzing XMM-Newton observations of the low mass X-ray binary Sco X-1. We use simple models based on the O I atomic cross section from different sources to fit the data and evaluate the impact of the atomic data in the interpretation of astrophysical observations. We show that relatively small differences in the atomic calculations can yield spurious results. We also show that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21 - 24.5 Angstrom wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of Epsilon = 10(exp -4) erg/sq cm, and an oxygen column density of N(sub O) approx. = 8-10 x 10(exp 17)/sq cm. Our models are able to reproduce both the K edge and the K(alpha) absorption line from O I, which are the two main features in this region. We find no conclusive evidence for absorption by other than atomic oxygen.

Reverse saturable absorption studies in polymerized indole - Effect of polymerization in the phenomenal enhancement of third order optical nonlinearity

NASA Astrophysics Data System (ADS)

Jayakrishnan, K.; Joseph, Antony; Bhattathiripad, Jayakrishnan; Ramesan, M. T.; Chandrasekharan, K.; Siji Narendran, N. K.

2016-04-01

We report our results on the identification of large order enhancement in nonlinear optical coefficients of polymerized indole and its comparative study with reference to its monomer counterpart. Indole monomer shows virtually little third order effects whereas its polymerized version exhibits phenomenal increase in its third order nonlinear optical parameters such as nonlinear refractive index and nonlinear absorption. Open aperture Z-scan trace of polyindole done with Q-switched Nd:YAG laser source (532 nm, 7 ns), shows β value as high as 89 cm/GW at a beam energy of 0.83 GW/cm2. Closed aperture Z-scan done at identical energies reveals nonlinear refractive index of the order of -3.55 × 10-17 m2/W. Band gap measurement of polyindole was done with UV-Vis absorption spectra and compared with that of Indole. FTIR spectra of the monomer and polymerized versions were recorded and relevant bond formations were confirmed from the characteristic peaks. Photo luminescent spectra were investigated to know the emission features of both molecules. Beam energy (I0) versus nonlinear absorption coefficient (β) plot indicates reverse saturable type of absorption behaviour in polyindole molecules. Degenerate Four Wave Mixing (DFWM) plot of polyindole reveals quite a cubic dependence between probe and phase conjugate signal and the resulting χ(3) is comparable with Z-scan results. Optical limiting efficiency of polyindole is comparable with certain derivatives of porphyrins, phthalocyanines and graphene oxides.

Some aspects of coupling-induced sound absorption in enclosures.

PubMed

Sum, K S; Pan, J

2003-08-01

It is known that the coupling between a modally reactive boundary structure of an enclosure and the enclosed sound field induces absorption in the sound field. However, the effect of this absorption on the sound-field response can vary significantly, even when material properties of the structure and dimensions of the coupled system are not changed. Although there have been numerous investigations of coupling between a structure and an enclosed sound field, little work has been done in the area of sound absorption induced by the coupling. Therefore, characteristics of the absorption are not well understood and the extent of its influence on the behavior of the sound-field response is not clearly known. In this paper, the coupling of a boundary structure and an enclosed sound field in frequency bands above the low-frequency range is considered. Three aspects of the coupling-induced sound absorption are studied namely, the effects of exciting either the structure or the sound field directly, damping in the uncoupled sound field and damping in the uncoupled structure. The results provide an understanding of some features of the coupling-induced absorption and its significance to the sound-field response.

Absorption dynamics and delay time in complex potentials

NASA Astrophysics Data System (ADS)

Villavicencio, Jorge; Romo, Roberto; Hernández-Maldonado, Alberto

2018-05-01

The dynamics of absorption is analyzed by using an exactly solvable model that deals with an analytical solution to Schrödinger’s equation for cutoff initial plane waves incident on a complex absorbing potential. A dynamical absorption coefficient which allows us to explore the dynamical loss of particles from the transient to the stationary regime is derived. We find that the absorption process is characterized by the emission of a series of damped periodic pulses in time domain, associated with damped Rabi-type oscillations with a characteristic frequency, ω = (E + ε)/ℏ, where E is the energy of the incident waves and ‑ε is energy of the quasidiscrete state of the system induced by the absorptive part of the Hamiltonian; the width γ of this resonance governs the amplitude of the pulses. The resemblance of the time-dependent absorption coefficient with a real decay process is discussed, in particular the transition from exponential to nonexponential regimes, a well-known feature of quantum decay. We have also analyzed the effect of the absorptive part of the potential on the dynamical delay time, which behaves differently from the one observed in attractive real delta potentials, exhibiting two regimes: time advance and time delay.

Photoluminescence and gain/absorption spectra of a driven-dissipative electron-hole-photon condensate

NASA Astrophysics Data System (ADS)

Hanai, Ryo; Littlewood, Peter B.; Ohashi, Yoji

2018-06-01

We investigate theoretically nonequilibrium effects on photoluminescence and gain/absorption spectra of a driven-dissipative exciton-polariton condensate, by employing the combined Hartree-Fock-Bogoliubov theory with the generalized random phase approximation extended to the Keldysh formalism. Our calculated photoluminescence spectra is in semiquantitative agreement with experiments, where features such as a blue shift of the emission from the condensate, the appearance of the dispersionless feature of a diffusive Goldstone mode, and the suppression of the dispersive profile of the mode are obtained. We show that the nonequilibrium nature of the exciton-polariton condensate strongly suppresses the visibility of the Bogoliubov dispersion in the negative energy branch (ghost branch) in photoluminescence spectra. We also show that the trace of this branch can be captured as a hole burning effect in gain/absorption spectra. Our results indicate that the nonequilibrium nature of the exciton-polariton condensate strongly reduces quantum depletion, while a scattering channel to the ghost branch is still present.

An x-ray absorption study of the iron site in bacterial photosynthetic reaction centers.

PubMed Central

Bunker, G; Stern, E A; Blankenship, R E; Parson, W W

1982-01-01

Measurements were made of the extended x-ray absorption fine structure (EXAFS) of the iron site in photosynthetic reaction centers from the bacterium Rhodopseudomonas sphaeroides. Forms with two quinones, two quinones with added o-phenanthroline, and one quinone were studied. Only the two forms containing two quinones maintained their integrity and were analyzed. The spectra show directly that the added o-phenanthroline does not chelate the iron atom. Further analysis indicates that the iron is octahedrally coordinated by nitrogen and/or oxygen atoms located at various distances, with the average value of about 2.14 A. The analysis suggests that most of the ligands are nitrogens and that three of the nitrogen ligands belong to histidine rings. This interpretation accounts for several unusual features of the EXAFS spectrum. We speculate that the quinones are bound to the histidine rings in some manner. Qualitative features of the absorption edge spectra also are discussed and are related to the Fe-ligand distance. PMID:6977382

Fat-soluble vitamin intestinal absorption: absorption sites in the intestine and interactions for absorption.

PubMed

Goncalves, Aurélie; Roi, Stéphanie; Nowicki, Marion; Dhaussy, Amélie; Huertas, Alain; Amiot, Marie-Josèphe; Reboul, Emmanuelle

2015-04-01

The interactions occurring at the intestinal level between the fat-soluble vitamins A, D, E and K (FSVs) are poorly documented. We first determined each FSV absorption profile along the duodenal-colonic axis of mouse intestine to clarify their respective absorption sites. We then investigated the interactions between FSVs during their uptake by Caco-2 cells. Our data show that vitamin A was mostly absorbed in the mouse proximal intestine, while vitamin D was absorbed in the median intestine, and vitamin E and K in the distal intestine. Significant competitive interactions for uptake were then elucidated among vitamin D, E and K, supporting the hypothesis of common absorption pathways. Vitamin A also significantly decreased the uptake of the other FSVs but, conversely, its uptake was not impaired by vitamins D and K and even promoted by vitamin E. These results should be taken into account, especially for supplement formulation, to optimise FSV absorption. Copyright © 2014 Elsevier Ltd. All rights reserved.

Differential optical absorption spectrometer for measurement of tropospheric pollutants

NASA Astrophysics Data System (ADS)

Evangelisti, F.; Baroncelli, A.; Bonasoni, P.; Giovanelli, G.; Ravegnani, F.

1995-05-01

Our institute has recently developed a differential optical absorption spectrometry system called the gas analyzer spectrometer correlating optical absorption differences (GASCOAD), which features as a detector a linear image sensor that uses an artificial light source for long-path tropospheric-pollution monitoring. The GASCOAD, its method of eliminating interference from background sky light, and subsequent spectral analysis are reported and discussed. The spectrometer was used from 7 to 22 February 1993 in Milan, a heavily polluted metropolitan area, to measure the concentrations of SO2, NO2, O3, and HNO2 averaged over a 1.7-km horizontal light path. The findings are reported and briefly discussed.

Photoionization-driven Absorption-line Variability in Balmer Absorption Line Quasar LBQS 1206+1052

SciTech Connect

Sun, Luming; Zhou, Hongyan; Ji, Tuo

In this paper we present an analysis of absorption-line variability in mini-BAL quasar LBQS 1206+1052. The Sloan Digital Sky Survey spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of ∼700 and ∼1400 km s{sup −1} relative to the quasar rest frame. The former component shows rare Balmer absorption, which is an indicator of high-density absorbing gas; thus, the quasar is worth follow-up spectroscopic observations. Our follow-up optical and near-infrared spectra using MMT, YFOSC, TSpec, and DBSP reveal that the strengths of the absorption lines vary for both components, while the velocities do notmore » change. We reproduce all of the spectral data by assuming that only the ionization state of the absorbing gas is variable and that all other physical properties are invariable. The variation of ionization is consistent with the variation of optical continuum from the V -band light curve. Additionally, we cannot interpret the data by assuming that the variability is due to a movement of the absorbing gas. Therefore, our analysis strongly indicates that the absorption-line variability in LBQS 1206+1052 is photoionization driven. As shown from photoionization simulations, the absorbing gas with blueshift velocity of ∼700 km s{sup −1} has a density in the range of 10{sup 9} to 10{sup 10} cm{sup −3} and a distance of ∼1 pc, and the gas with blueshift velocity of ∼1400 km s{sup −1} has a density of 10{sup 3} cm{sup −3} and a distance of ∼1 kpc.« less

Photoionization-driven Absorption-line Variability in Balmer Absorption Line Quasar LBQS 1206+1052

NASA Astrophysics Data System (ADS)

Sun, Luming; Zhou, Hongyan; Ji, Tuo; Jiang, Peng; Liu, Bo; Liu, Wenjuan; Pan, Xiang; Shi, Xiheng; Wang, Jianguo; Wang, Tinggui; Yang, Chenwei; Zhang, Shaohua; Miller, Lauren P.

2017-04-01

In this paper we present an analysis of absorption-line variability in mini-BAL quasar LBQS 1206+1052. The Sloan Digital Sky Survey spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of ˜700 and ˜1400 km s-1 relative to the quasar rest frame. The former component shows rare Balmer absorption, which is an indicator of high-density absorbing gas; thus, the quasar is worth follow-up spectroscopic observations. Our follow-up optical and near-infrared spectra using MMT, YFOSC, TSpec, and DBSP reveal that the strengths of the absorption lines vary for both components, while the velocities do not change. We reproduce all of the spectral data by assuming that only the ionization state of the absorbing gas is variable and that all other physical properties are invariable. The variation of ionization is consistent with the variation of optical continuum from the V-band light curve. Additionally, we cannot interpret the data by assuming that the variability is due to a movement of the absorbing gas. Therefore, our analysis strongly indicates that the absorption-line variability in LBQS 1206+1052 is photoionization driven. As shown from photoionization simulations, the absorbing gas with blueshift velocity of ˜700 km s-1 has a density in the range of 109 to 1010 cm-3 and a distance of ˜1 pc, and the gas with blueshift velocity of ˜1400 km s-1 has a density of 103 cm-3 and a distance of ˜1 kpc.

Novel Features for Brain-Computer Interfaces

PubMed Central

Woon, W. L.; Cichocki, A.

2007-01-01

While conventional approaches of BCI feature extraction are based on the power spectrum, we have tried using nonlinear features for classifying BCI data. In this paper, we report our test results and findings, which indicate that the proposed method is a potentially useful addition to current feature extraction techniques. PMID:18364991

Bicarbonate secretion and solute absorption in forestomach of the llama.

PubMed

Rübsamen, K; Engelhardt, W V

1978-07-01

Bicarbonate appearance in the lumen and its relationship to solute absorption were studied in a Pavlov pouch in the cardiac region of the first compartment of the llama forestomach. HCO3- appearance showed no diurnal variation. HCO3- accumulation was highly dependent on the pH of the solution used. The HCO3- ion probably is formed from CO2 diffusing into the lumen from the serosal side, as a result of cell metabolism and of OH- ions. HCO3- accumulation was closely related to volatile fatty acid (VFA) absorption. The ratio of HCO3- appearance to VFA absorption depended on the pH of the solution. At a pH of 6.6, about 0.1 mol HCO3- and, at a pH of 7.8, 0.9 mol HCO3- appeared per mole absorbed VFA, indicating that at slightly alkaline pH nearly all H+ ions required for the nonionic absorption of VFA appeared to be delivered from the dissociation of H2CO3. Bicarbonate gain and VFA absorption were increased when animals were not fed for 48 h. Sodium absorption was related to VFA as well as water absorption.

Time-variable Aluminum Absorption in the Polar AR Ursae Majoris, and an Updated Estimate for the Mass of the White Dwarf

NASA Astrophysics Data System (ADS)

Bai, Yu; Justham, Stephen; Liu, JiFeng; Guo, JinCheng; Gao, Qing; Gong, Hang

2016-09-01

We present spectra of the extreme polar AR Ursae Majoris (AR UMa), which display a clear Al I absorption doublet, alongside spectra taken less than a year earlier in which that feature is not present. Re-examination of earlier SDSS spectra indicates that the Al I absorption doublet was also present ≈8 years before our first non-detection. We conclude that this absorbing material is unlikely to be on the surface of either the white dwarf (WD) or the donor star. We suggest that this Al I absorption feature arises in circumstellar material, perhaps produced by the evaporation of asteroids as they approach the hot WD. The presence of any remaining reservoir of rocky material in AR UMa might help to constrain the prior evolution of this unusual binary system. We also apply spectral decomposition to find the stellar parameters of the M dwarf companion, and attempt to dynamically measure the mass of the WD in AR UMa by considering both the radial velocity curves of the H β emission line and the Na I absorption line. Thereby we infer a mass range for the WD in AR UMa of 0.91 M ⊙ < M WD < 1.24 M ⊙.

TIME-VARIABLE ALUMINUM ABSORPTION IN THE POLAR AR URSAE MAJORIS, AND AN UPDATED ESTIMATE FOR THE MASS OF THE WHITE DWARF

SciTech Connect

Bai, Yu; Justham, Stephen; Liu, JiFeng

2016-09-01

We present spectra of the extreme polar AR Ursae Majoris (AR UMa), which display a clear Al i absorption doublet, alongside spectra taken less than a year earlier in which that feature is not present. Re-examination of earlier SDSS spectra indicates that the Al i absorption doublet was also present ≈8 years before our first non-detection. We conclude that this absorbing material is unlikely to be on the surface of either the white dwarf (WD) or the donor star. We suggest that this Al i absorption feature arises in circumstellar material, perhaps produced by the evaporation of asteroids as theymore » approach the hot WD. The presence of any remaining reservoir of rocky material in AR UMa might help to constrain the prior evolution of this unusual binary system. We also apply spectral decomposition to find the stellar parameters of the M dwarf companion, and attempt to dynamically measure the mass of the WD in AR UMa by considering both the radial velocity curves of the H {sub β} emission line and the Na i absorption line. Thereby we infer a mass range for the WD in AR UMa of 0.91 M {sub ⊙} < M {sub WD} < 1.24 M {sub ⊙}.« less

The relative importance of aerosol scattering and absorption in remote sensing

NASA Technical Reports Server (NTRS)

Fraser, R. S.; Kaufman, Y. J.

1985-01-01

Previous attempts to explain the effect of aerosols on satellite measurements of surface properties for the visible and near-infrared spectrum have emphasized the amount of aerosols without consideration of their absorption properties. In order to estimate the importance of absorption, the radiances of the sunlight scattered from models of the earth-atmosphere system are computed as functions of the aerosol optical thickness and absorption. The absorption effect is small where the surface reflectance is weak, but is important for strong reflectance. These effects on classification of surface features, measuring vegetation index, and measuring surface reflectance are presented.

Enhanced absorption of light by charged nanoparticles.

PubMed

Rosenkrantz, Etai; Arnon, Shlomi

2010-04-15

We found that various charged nanoparticles (NPs) can raise the attenuation of electromagnetic (EM) radiation over 30 times more efficiently during resonance in comparison to equivalent noncharged particles for a given set of parameters. A condition that indicates a state of resonance between the incident EM radiation and the NP surface excitations is mathematically derived. Our results shed light on the mechanism responsible for the strong absorption of light by such charged NPs. The outcome of this research could help to design a new generation of communication devices as well as a new technique for biological cell imaging.

Designing using manufacturing features

NASA Astrophysics Data System (ADS)

Szecsi, T.; Hoque, A. S. M.

2012-04-01

This paper presents a design system that enables the composition of a part using manufacturing features. Features are selected from feature libraries. Upon insertion, the system ensures that the feature does not contradict the design-for-manufacture rules. This helps eliminating costly manufacturing problems. The system is developed as an extension to a commercial CAD/CAM system Pro/Engineer.

Effects of the morphology of CIPs on microwave absorption behaviors

NASA Astrophysics Data System (ADS)

Woo, Soobin; Yoo, Chan-Sei; Kim, Hwijun; Lee, Mijung; Quevedo-Lopez, Manuel; Choi, Hyunjoo

2017-11-01

Electromagnetic (EM) wave absorption properties are affected by the thickness and surface area of absorbing materials. In this study, a facile ball-milling process was introduced to effectively reduce the diameter and increase the aspect ratio of carbonyl iron powder (CIP), which is one of the most commercially available EM-absorbing materials. The size, aspect ratio, and consequent surface area of CIP were manipulated by controlling the milling parameters to investigate their effects on EM absorption properties. The results indicated that ball-milled CIPs exhibited better EM wave absorption ability when compared with that of pristine CIPs. However, significant differences in minimum reflection loss values were not observed between CIPs with different morphologies and similar specific surface areas. Hence, both fine and flaky CIPs were considered as beneficial for EM wave absorption.[Figure not available: see fulltext.

Absorptive coding metasurface for further radar cross section reduction

NASA Astrophysics Data System (ADS)

Sui, Sai; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Feng, Mingde; Xu, Zhuo; Qu, Shaobo

2018-02-01

Lossless coding metasurfaces and metamaterial absorbers have been widely used for radar cross section (RCS) reduction and stealth applications, which merely depend on redirecting electromagnetic wave energy into various oblique angles or absorbing electromagnetic energy, respectively. Here, an absorptive coding metasurface capable of both the flexible manipulation of backward scattering and further wideband bistatic RCS reduction is proposed. The original idea is carried out by utilizing absorptive elements, such as metamaterial absorbers, to establish a coding metasurface. We establish an analytical connection between an arbitrary absorptive coding metasurface arrangement of both the amplitude and phase and its far-field pattern. Then, as an example, an absorptive coding metasurface is demonstrated as a nonperiodic metamaterial absorber, which indicates an expected better performance of RCS reduction than the traditional lossless coding metasurface and periodic metamaterial-absorber. Both theoretical analysis and full-wave simulation results show good accordance with the experiment.

VUV absorption spectroscopy of bacterial spores and DNA components

NASA Astrophysics Data System (ADS)

Fiebrandt, Marcel; Lackmann, Jan-Wilm; Raguse, Marina; Moeller, Ralf; Awakowicz, Peter; Stapelmann, Katharina

2017-01-01

Low-pressure plasmas can be used to inactivate bacterial spores and sterilize goods for medical and pharmaceutical applications. A crucial factor are damages induced by UV and VUV radiation emitted by the plasma. To analyze inactivation processes and protection strategies of spores, absorption spectra of two B. subtilis strains are measured. The results indicate, that the inner and outer coat of the spore significantly contribute to the absorption of UV-C and also of the VUV, protecting the spore against radiation based damages. As the sample preparation can significantly influence the absorption spectra due to salt residues, the cleaning procedure and sample deposition is tested for its reproducibility by measuring DNA oligomers and pUC18 plasmid DNA. The measurements are compared and discussed with results from the literature, showing a strong decrease of the salt content enabling the detection of absorption structures in the samples.

Monitoring Telluric Water Absorption with CAMAL

NASA Astrophysics Data System (ADS)

Baker, Ashley; Blake, Cullen; Sliski, David

2017-01-01

Ground-based observations are severely limited by telluric water vapor absorption features, which are highly variable in time and significantly complicate both spectroscopy and photometry in the near-infrared (NIR). To achieve the stability required to study Earth-sized exoplanets, monitoring the precipitable water vapor (PWV) becomes necessary to mitigate the impact of telluric lines on radial velocity measurements and transit light curves. To address this issue, we present the Camera for the Automatic Monitoring of Atmospheric Lines (CAMAL), a stand-alone, inexpensive 6-inch aperture telescope dedicated to measuring PWV at the Whipple Observatory. CAMAL utilizes three NIR narrowband filters to trace the amount of atmospheric water vapor affecting simultaneous observations with the MINiature Exoplanet Radial Velocity Array (MINERVA) and MINERVA-Red telescopes. We present the current design of CAMAL, discuss our calibration methods, and show PWV measurements taken with CAMAL compared to those of a nearby GPS water vapor monitor.

Absorption band Q model for the Earth

NASA Technical Reports Server (NTRS)

Anderson, D. L.; Given, J. W.

1981-01-01

Attenuation in solids and liquids, as measured by the quality factor Q, is typically frequency dependent. In seismology, however, Q is usually assumed to be independent of frequency. Body wave, surface wave, and normal mode data are used to place constraints on the frequency dependence of Q in the mantle. Specific features of the absorption band model are: low-Q in the seismic band at both the top and the base of the mantle, low-Q for long-period body waves in the outer core, an inner core Q sub s that increases with period, and low Q sub p/Q sub s at short periods in the middle mantle.

Evaluation of wavelet spectral features in pathological detection and discrimination of yellow rust and powdery mildew in winter wheat with hyperspectral reflectance data

NASA Astrophysics Data System (ADS)

Shi, Yue; Huang, Wenjiang; Zhou, Xianfeng

2017-04-01

Hyperspectral absorption features are important indicators of characterizing plant biophysical variables for the automatic diagnosis of crop diseases. Continuous wavelet analysis has proven to be an advanced hyperspectral analysis technique for extracting absorption features; however, specific wavelet features (WFs) and their relationship with pathological characteristics induced by different infestations have rarely been summarized. The aim of this research is to determine the most sensitive WFs for identifying specific pathological lesions from yellow rust and powdery mildew in winter wheat, based on 314 hyperspectral samples measured in field experiments in China in 2002, 2003, 2005, and 2012. The resultant WFs could be used as proxies to capture the major spectral absorption features caused by infestation of yellow rust or powdery mildew. Multivariate regression analysis based on these WFs outperformed conventional spectral features in disease detection; meanwhile, a Fisher discrimination model exhibited considerable potential for generating separable clusters for each infestation. Optimal classification returned an overall accuracy of 91.9% with a Kappa of 0.89. This paper also emphasizes the WFs and their relationship with pathological characteristics in order to provide a foundation for the further application of this approach in monitoring winter wheat diseases at the regional scale.

[Analysis of UV-visible absorption spectrum on the decolorization of industrial wastewater by disinfection].

PubMed

Huang, Xin; Wang, Long-Yong; Gao, Nai-Yun; Li, Wei-Guo

2012-10-01

The UV-Visible absorption spectrum of industrial wastewater was explored to introduce a substituting method determining the color of water, and to compare the decolorization efficacy of different disinfectants. The results show that the visible absorption spectrum(350-600 nm), instead of ultraviolet absorption spectrum, should be applied to characterize the color of wastewater. There is a good correlation between the features of visible absorption spectrum and the true color of wastewater. Both ozone and chlorine dioxide has a better decolorization performance than chlorine. However, the color of chlorine dioxide itself has a negative effect on decolorization. The changes in the features of visible absorption spectrum effectively reflect the variations in the color of wastewater after disinfection.

Architecture for Absorption Based Heaters

SciTech Connect

Moghaddam, Saeed; Chugh, Devesh

An absorption based heater is constructed on a fluid barrier heat exchanging plate such that it requires little space in a structure. The absorption based heater has a desorber, heat exchanger, and absorber sequentially placed on the fluid barrier heat exchanging plate. The vapor exchange faces of the desorber and the absorber are covered by a vapor permeable membrane that is permeable to a refrigerant vapor but impermeable to an absorbent. A process fluid flows on the side of the fluid barrier heat exchanging plate opposite the vapor exchange face through the absorber and subsequently through the heat exchanger. Themore » absorption based heater can include a second plate with a condenser situated parallel to the fluid barrier heat exchanging plate and opposing the desorber for condensation of the refrigerant for additional heating of the process fluid.« less

Absorption of Orally Administered Hyaluronan.

PubMed

Kimura, Mamoru; Maeshima, Takuya; Kubota, Takumi; Kurihara, Hitoshi; Masuda, Yasunobu; Nomura, Yoshihiro

2016-12-01

Hyaluronan (HA) has been utilized as a supplement. However, the absorption of orally administrated HA remains controversial. The degradation and absorption of HA in the intestine were investigated in this study. HA excretion into the feces, degradation in the intestinal tract, absorption through the large intestine, and translocation to the blood and skin were examined. HA administered orally was not detected in rat feces. HA was degraded by cecal content, but not by artificial gastric juice and intestinal juice. Oligosaccharide HA passed through excised large intestine sacs. Furthermore, disaccharides, tetrasaccharides, and polysaccharides HA were distributed to the skin of rats following oral administration of high molecular weight HA (300 kDa). The results of the study suggest that orally administered HA is degraded to oligosaccharides by intestinal bacteria, and oligosaccharide HA is absorbed in the large intestine and is subsequently distributed throughout the tissues, including the skin.

Thermodynamic derivatives of infrared absorptance

NASA Technical Reports Server (NTRS)

Broersma, S.; Walls, W. L.

1974-01-01

Calculation of the concentration, pressure, and temperature dependence of the spectral absorptance of a vibrational absorption band. A smooth thermodynamic dependence was found for wavelength intervals where the average absorptance is less than 0.65. Individual rotational lines, whose parameters are often well known, were used as bases in the calculation of medium resolution spectra. Two modes of calculation were combined: well-separated rotational lines plus interaction terms, or strongly overlapping lines that were represented by a compound line of similar shape plus corrections. The 1.9- and 6.3-micron bands of H2O and the 4.3-micron band of CO2 were examined in detail and compared with experiment.

Neutron absorption constraints on the composition of 4 Vesta

NASA Astrophysics Data System (ADS)

Prettyman, Thomas H.; Mittlefehldt, David W.; Yamashita, Naoyuki; Beck, Andrew W.; Feldman, William C.; Hendricks, John S.; Lawrence, David J.; McCoy, Timothy J.; McSween, Harry Y.; Peplowski, Patrick N.; Reedy, Robert C.; Toplis, Michael J.; Corre, Lucille; Mizzon, Hugau; Reddy, Vishnu; Titus, Timothy N.; Raymond, Carol A.; Russell, Christopher T.

2013-11-01

Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock-forming elements. From a circular, polar low-altitude mapping orbit, GRaND sampled the regolith to decimeter depths with a spatial resolution of about 300 km. At this spatial scale, the variation in neutron absorption is about seven times lower than that of the Moon. The observed variation is consistent with the range of absorption for howardite whole-rock compositions, which further supports the connection between Vesta and the howardite, eucrite, and diogenite meteorites. We find a strong correlation between neutron absorption and the percentage of eucritic materials in howardites and polymict breccias, which enables petrologic mapping of Vesta's surface. The distribution of basaltic eucrite and diogenite determined from neutron absorption measurements is qualitatively similar to that indicated by visible and near infrared spectroscopy. The Rheasilvia basin and ejecta blanket has relatively low absorption, consistent with Mg-rich orthopyroxene. Based on a combination of Fe and neutron absorption measurements, olivine-rich lithologies are not detected on the spatial scales sampled by GRaND. The sensitivity of GRaND to the presence of mantle material is described and implications for the absence of an olivine signature are discussed. High absorption values found in Vesta's "dark" hemisphere, where exogenic hydrogen has accumulated, indicate that this region is richer in basaltic eucrite, representative of Vesta's ancient upper crust.

Neutron absorption constraints on the composition of 4 Vesta

USGS Publications Warehouse

Prettyman, Thomas H.; Mittlefehldt, David W.; Yamashita, Naoyuki; Beck, Andrew W.; Feldman, William C.; Hendricks, John S.; Lawrence, David J.; McCoy, Timothy J.; McSween, Harry Y.; Paplowski, Patrick N.; Reedy, Robert C.; Toplis, Michael J.; Le Corre, Lucille; Mizzon, Hugau; Reddy, Vishnu; Titus, Timothy N.; Raymond, Carol A.; Russell, Christopher T.

2013-01-01

Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock-forming elements. From a circular, polar low-altitude mapping orbit, GRaND sampled the regolith to decimeter depths with a spatial resolution of about 300 km. At this spatial scale, the variation in neutron absorption is about seven times lower than that of the Moon. The observed variation is consistent with the range of absorption for howardite whole-rock compositions, which further supports the connection between Vesta and the howardite, eucrite, and diogenite meteorites. We find a strong correlation between neutron absorption and the percentage of eucritic materials in howardites and polymict breccias, which enables petrologic mapping of Vesta's surface. The distribution of basaltic eucrite and diogenite determined from neutron absorption measurements is qualitatively similar to that indicated by visible and near infrared spectroscopy. The Rheasilvia basin and ejecta blanket has relatively low absorption, consistent with Mg-rich orthopyroxene. Based on a combination of Fe and neutron absorption measurements, olivine-rich lithologies are not detected on the spatial scales sampled by GRaND. The sensitivity of GRaND to the presence of mantle material is described and implications for the absence of an olivine signature are discussed. High absorption values found in Vesta's “dark” hemisphere, where exogenic hydrogen has accumulated, indicate that this region is richer in basaltic eucrite, representative of Vesta's ancient upper crust.

Absorption-heat-pump system

DOEpatents

Grossman, G.; Perez-Blanco, H.

1983-06-16

An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

An Inexpensive Optical Absorption Experiment

NASA Astrophysics Data System (ADS)

Greenslade, Thomas B.

2006-09-01

This optical absorption experiment can be put together in only a few minutes with materials found in most secondary or undergraduate stockrooms. The absorption material is the partly transparent flexible anti-static plastic material used to package solid-state devices. The detector is a hand-held photographic exposure meter of the type that was in common use before the advent of point-and-shoot cameras. A graph of the intensity of the transmitted light as a function of the number of sheets of the material is a decreasing exponential. The emphasis of the experiment is on the mathematical form.

Constraining Cometary Crystal Shapes from IR Spectral Features

NASA Technical Reports Server (NTRS)

Wooden, Diane H.; Lindsay, Sean; Harker, David E.; Kelley, Michael S. P.; Woodward, Charles E.; Murphy, James Richard

2013-01-01

A major challenge in deriving the silicate mineralogy of comets is ascertaining how the anisotropic nature of forsterite crystals affects the spectral features' wavelength, relative intensity, and asymmetry. Forsterite features are identified in cometary comae near 10, 11.05-11.2, 16, 19, 23.5, 27.5 and 33 microns [1-10], so accurate models for forsterite's absorption efficiency (Qabs) are a primary requirement to compute IR spectral energy distributions (SEDs, lambdaF lambda vs. lambda) and constrain the silicate mineralogy of comets. Forsterite is an anisotropic crystal, with three crystallographic axes with distinct indices of refraction for the a-, b-, and c-axis. The shape of a forsterite crystal significantly affects its spectral features [13-16]. We need models that account for crystal shape. The IR absorption efficiencies of forsterite are computed using the discrete dipole approximation (DDA) code DDSCAT [11,12]. Starting from a fiducial crystal shape of a cube, we systematically elongate/reduce one of the crystallographic axes. Also, we elongate/reduce one axis while the lengths of the other two axes are slightly asymmetric (0.8:1.2). The most significant grain shape characteristic that affects the crystalline spectral features is the relative lengths of the crystallographic axes. The second significant grain shape characteristic is breaking the symmetry of all three axes [17]. Synthetic spectral energy distributions using seven crystal shape classes [17] are fit to the observed SED of comet C/1995 O1 (Hale-Bopp). The Hale-Bopp crystalline residual better matches equant, b-platelets, c-platelets, and b-columns spectral shape classes, while a-platelets, a-columns and c-columns worsen the spectral fits. Forsterite condensation and partial evaporation experiments demonstrate that environmental temperature and grain shape are connected [18-20]. Thus, grain shape is a potential probe for protoplanetary disk temperatures where the cometary crystalline

Metal powder absorptivity: Modeling and experiment

DOE PAGES

Boley, C. D.; Mitchell, S. C.; Rubenchik, A. M.; ...

2016-08-10

Here, we present results of numerical modeling and direct calorimetric measurements of the powder absorptivity for a number of metals. The modeling results generally correlate well with experiment. We show that the powder absorptivity is determined, to a great extent, by the absorptivity of a flat surface at normal incidence. Our results allow the prediction of the powder absorptivity from normal flat-surface absorptivity measurements.

Metal powder absorptivity: Modeling and experiment

SciTech Connect

Boley, C. D.; Mitchell, S. C.; Rubenchik, A. M.

Here, we present results of numerical modeling and direct calorimetric measurements of the powder absorptivity for a number of metals. The modeling results generally correlate well with experiment. We show that the powder absorptivity is determined, to a great extent, by the absorptivity of a flat surface at normal incidence. Our results allow the prediction of the powder absorptivity from normal flat-surface absorptivity measurements.

Evidence for sulphur implantation in Europa's UV absorption band

NASA Technical Reports Server (NTRS)

Lane, A. L.; Nelson, R. M.; Matson, D. L.

1981-01-01

The UV spectral characteristics of the Galilean satellites are investigated (using data from the International Ultraviolet Explorer (IUE) spacecraft) as a function of the orbital position, large-scale areal variability, and temporal dynamics. The discovery of an absorption feature at 280 nm in Europa's reflection spectrum is reported and observations show that the absorption is strongest on the trailing hemisphere (central longitude 270 degrees). The feature resembles SO2 and seems to result from S-O bond formation between deeply implanted sulphur atoms and the adjacent damaged water-ice-lattice. The sulphur supposedly comes from energetic (hundreds of keV) sulphur ions that are present in the Jovian magnetosphere. An appropriate equilibrium condition can be found to match the observed spectral data if sputtering erosion occurs at no greater than approximately 20 meters per one billion years.

Developing Indicators of Student Coursework.

ERIC Educational Resources Information Center

McDonnell, Lorraine M.; Ormseth, Tor

The School Reform Assessment (SRA) project began in 1987 with the objective of developing indicators of student coursework that reliably and validly measure this central feature of schooling, while remaining sensitive to major policy changes and the information needs of policymakers, and efficiently collecting and reporting data. This paper…

Absorption Mode FT-ICR Mass Spectrometry Imaging

SciTech Connect

Smith, Donald F.; Kilgour, David P.; Konijnenburg, Marco

2013-12-03

Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here we present the first use of absorption mode formore » Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image and then these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode ?Datacubes? for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.« less

Credibility judgments of narratives: language, plausibility, and absorption.

PubMed

Nahari, Galit; Glicksohn, Joseph; Nachson, Israel

2010-01-01

Two experiments were conducted in order to find out whether textual features of narratives differentially affect credibility judgments made by judges having different levels of absorption (a disposition associated with rich visual imagination). Participants in both experiments were exposed to a textual narrative and requested to judge whether the narrator actually experienced the event he described in his story. In Experiment 1, the narrative varied in terms of language (literal, figurative) and plausibility (ordinary, anomalous). In Experiment 2, the narrative varied in terms of language only. The participants' perceptions of the plausibility of the story described and the extent to which they were absorbed in reading were measured. The data from both experiments together suggest that the groups applied entirely different criteria in credibility judgments. For high-absorption individuals, their credibility judgment depends on the degree to which the text can be assimilated into their own vivid imagination, whereas for low-absorption individuals it depends mainly on plausibility. That is, high-absorption individuals applied an experiential mental set while judging the credibility of the narrator, whereas low-absorption individuals applied an instrumental mental set. Possible cognitive mechanisms and implications for credibility judgments are discussed.

Emission from water vapor and absorption from other gases at 5-7.5 μm in Spitzer-IRS Spectra Of Protoplanetary Disks

SciTech Connect

Sargent, B. A.; Forrest, W.; Watson, Dan M.

We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming region showing emission in Spitzer Space Telescope Infrared Spectrograph 5-7.5 μm spectra from water vapor and absorption from other gases in these stars' protoplanetary disks. Seven stars' spectra show an emission feature at 6.6 μm due to the ν{sub 2} = 1-0 bending mode of water vapor, with the shape of the spectrum suggesting water vapor temperatures >500 K, though some of these spectra also show indications of an absorption band, likely from another molecule. This water vapor emission contrasts with the absorption from warm water vapor seenmore » in the spectrum of the FU Orionis star V1057 Cyg. The other 6 of the 13 stars have spectra showing a strong absorption band, peaking in strength at 5.6-5.7 μm, which for some is consistent with gaseous formaldehyde (H{sub 2}CO) and for others is consistent with gaseous formic acid (HCOOH). There are indications that some of these six stars may also have weak water vapor emission. Modeling of these stars' spectra suggests these gases are present in the inner few AU of their host disks, consistent with recent studies of infrared spectra showing gas in protoplanetary disks.« less

Escalator Design Features Evaluation

DOT National Transportation Integrated Search

1982-05-01

This study provides an evaluation of the effectiveness of several special design features associated with escalators in rail transit systems. The objective of the study was to evaluate the effectiveness of three escalator design features: (1) mat ope...

Variability of absorption heat pump efficiency for domestic water heating and space heating based on time-weighted bin analysis

DOE PAGES

Ally, Moonis Raza; Sharma, Vishaldeep

2017-11-02

Natural gas-driven absorption heat pumps are under renewed scrutiny as a viable technology for space conditioning and water heating for residential and commercial applications because of natural gas production trends, pricing, and the speculation that it might be a “bridge fuel” in the global transition towards energy sustainability. Since any level of natural gas combustion contributes to atmospheric carbon dioxide accumulation, the merits of natural gas consuming absorption technology are re-examined in this paper from the point of view of expected efficiency throughout the United States using a time-weighted bin temperature analysis. Such analyses are necessary because equipment standards formore » rated performance is restricted to one set ambient condition, whereas in actual practice, the absorption heat pump (AHP) must perform over a considerably wider range of external conditions, where its efficiency may be vastly different from that at the rated condition. Quantification of variation in efficiency and system performance are imperative to address how to provide the desired utility with the least environmental impact. In this paper, we examine limiting features in absorption heat pumps and relate it to systemic performances in sixteen cities across all eight climate zones in the U.S, each containing fifteen bin temperatures. The results indicate that the true expectation of performance of an AHP is significantly less than what might be optimized for the rated condition. Statistical measures of the variation in water heating COPs show that for most cities, the COP at the rated conditions is outside the 95% Confidence Interval. Moreover, it is concluded that deployment of absorption heat pump water heaters (AHPWH) may be restricted geographically by outdoor temperature constraints.« less

Variability of absorption heat pump efficiency for domestic water heating and space heating based on time-weighted bin analysis

SciTech Connect

Ally, Moonis Raza; Sharma, Vishaldeep

Natural gas-driven absorption heat pumps are under renewed scrutiny as a viable technology for space conditioning and water heating for residential and commercial applications because of natural gas production trends, pricing, and the speculation that it might be a “bridge fuel” in the global transition towards energy sustainability. Since any level of natural gas combustion contributes to atmospheric carbon dioxide accumulation, the merits of natural gas consuming absorption technology are re-examined in this paper from the point of view of expected efficiency throughout the United States using a time-weighted bin temperature analysis. Such analyses are necessary because equipment standards formore » rated performance is restricted to one set ambient condition, whereas in actual practice, the absorption heat pump (AHP) must perform over a considerably wider range of external conditions, where its efficiency may be vastly different from that at the rated condition. Quantification of variation in efficiency and system performance are imperative to address how to provide the desired utility with the least environmental impact. In this paper, we examine limiting features in absorption heat pumps and relate it to systemic performances in sixteen cities across all eight climate zones in the U.S, each containing fifteen bin temperatures. The results indicate that the true expectation of performance of an AHP is significantly less than what might be optimized for the rated condition. Statistical measures of the variation in water heating COPs show that for most cities, the COP at the rated conditions is outside the 95% Confidence Interval. Moreover, it is concluded that deployment of absorption heat pump water heaters (AHPWH) may be restricted geographically by outdoor temperature constraints.« less

Calcium Absorption from Fortified Ice Cream Formulations Compared with Calcium Absorption from Milk

PubMed Central

van der Hee, Regine M.; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S.M.J.E.; Rietveld, Anton G.; Wilkinson, Joy E.; Quail, Patricia J.; Berry, Mark J.; Dainty, Jack R.; Teucher, Birgit; Fairweather-Tait, Susan J.

2009-01-01

Objective Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Subjects/setting Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Statistical analysis Effects on calcium absorption were evaluated by analysis of variance. Results Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%±8%, 28%±5%, and 31%±9%, respectively, and did not differ significantly (P=0.159). Conclusions Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium. PMID:19394469

Bicarbonate absorption stimulates active calcium absorption in the rat proximal tubule.

PubMed Central

Bomsztyk, K; Calalb, M B

1988-01-01

To evaluate the effect of luminal bicarbonate on calcium reabsorption, rat proximal tubules were perfused in vivo. Perfusion solution contained mannitol to reduce water flux to zero. Total Ca concentration was measured by atomic absorption spectrometry, Ca ion concentration in the tubule lumen (CaL2+) and the peritubular capillary (CaP2+), and luminal pH (pHL) with ion-selective microelectrodes and transepithelial voltage (VTE) with conventional microelectrodes. When tubules were perfused with buffer-free Cl-containing solution, net Ca absorption (JCa) averaged 3.33 pmol/min. Even though VTE was 1.64 mV lumen-positive, CaL2+, 1.05 mM, did not fall below the concentration in the capillary blood, 1.07 mM. When 27 mM of Cl was replaced with HCO3, there was luminal fluid acidification. Despite a decrease in VTE and CaL2+, JCa increased to 7.13 pmol/min, indicating that the enhanced JCa could not be accounted for by the reduced electrochemical gradient, delta CCa. When acetazolamide or an analogue of amiloride was added to the HCO3 solution, JCa was not different from the buffer-free solution, suggesting that HCO3-stimulated JCa may be linked to acidification. To further test this hypothesis, we used 27 mM Hepes as the luminal buffer. With Hepes there was luminal fluid acidification and JCa was not different from the buffer-free solution but delta CCa was significantly reduced, indicating enhanced active calcium transport. We conclude from the results of the present study that HCO3 stimulates active Ca absorption, a process that may be linked to acidification-mediated HCO3 absorption. PMID:3366902

Calcium absorption from fortified ice cream formulations compared with calcium absorption from milk.

PubMed

van der Hee, Regine M; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S M J E; Rietveld, Anton G; Wilkinson, Joy E; Quail, Patricia J; Berry, Mark J; Dainty, Jack R; Teucher, Birgit; Fairweather-Tait, Susan J

2009-05-01

Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Effects on calcium absorption were evaluated by analysis of variance. Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%+/-8%, 28%+/-5%, and 31%+/-9%, respectively, and did not differ significantly (P=0.159). Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium.

Absorption of Bile Pigments by the Gall Bladder*

PubMed Central

Ostrow, J. Donald

1967-01-01

A technique is described for preparation in the guinea pig of an in situ, isolated, vascularized gall bladder that exhibits normal absorptive functions. Absorption of labeled bile pigments from the gall bladder was determined by the subsequent excretion of radioactivity in hepatic bile. Over a wide range of concentrations, unconjugated bilirubin-14C was well absorbed, whereas transfer of conjugated bilirubin proceeded slowly. Mesobilirubinogen-3H was absorbed poorly from whole bile, but was absorbed as rapidly as unconjugated bilirubin from a solution of pure conjugated bile salt. Bilirubin absorption was not impaired by iodoacetamide, 1.5 mM, or dinitrophenol, 1.0 mM, even though water transport was affected. This indicated that absorption of bilirubin was not dependent upon water transport, nor upon energy-dependent processes. The linear relationship between absorption and concentration of pigment at low concentrations in bile salt solutions suggested that pigment was transferred by passive diffusion. At higher pigment concentrations or in whole bile, this simple relationship was modified by interactions of pigment with bile salts and other constituents of bile. These interactions did not necessarily involve binding of bilirubin in micelles. The slow absorption of the more polar conjugates and photo-oxidative derivatives of bilirubin suggested that bilirubin was absorbed principally by nonionic, and partially, by ionic diffusion. Concentrations of pure conjugated bile salts above 3.5 mM were found to be injurious to the gall bladder mucosa. This mucosal injury did not affect the kinetics of bilirubin absorption. During in vitro incubation of bile at 37°C, decay of bilirubin and hydrolysis of the conjugate proceeded as first-order reactions. The effects of these processes on the kinetics of bilirubin absorption, and their possible role in the formation of “white bile” and in the demonstrated appearance of unconjugated bilirubin in hepatic bile, are discussed

Optical absorption and photoluminescence studies of gold nanoparticles deposited on porous silicon

PubMed Central

2013-01-01

We present an investigation on a coupled system consists of gold nanoparticles and silicon nanocrystals. Gold nanoparticles (AuNPs) embedded into porous silicon (PSi) were prepared using the electrochemical deposition method. Scanning electron microscope images and energy-dispersive X-ray results indicated that the growth of AuNPs on PSi varies with current density. X-ray diffraction analysis showed the presence of cubic gold phases with crystallite sizes around 40 to 58 nm. Size dependence on the plasmon absorption was studied from nanoparticles with various sizes. Comparison with the reference sample, PSi without AuNP deposition, showed a significant blueshift with decreasing AuNP size which was explained in terms of optical coupling between PSi and AuNPs within the pores featuring localized plasmon resonances. PMID:23331761

Cosmological Evolution of QSO Absorption Systems

NASA Astrophysics Data System (ADS)

Stengler-Larrea, Erik

1995-08-01

First, the evolution with cosmic time of the hydrogen clouds which produce the Lyman-alpha absorption lines is studied in dependence on the strength of these lines. From the analysis it is concluded that the results show no evidence of a dependence in the sense of stronger lines evolving faster, although for the resolution at which the used observations were done, it can not be ruled out. Within the same analysis, a distribution of the Doppler parameter of the lines was obtained, with large values and a wide spread. This parameter being an indicator of the gas temperature, this result is in accordance with high temperatures and, consequently, large ionised fractions and a large fraction of the baryonic matter of the universe being associated with these clouds. However, recent high resolution studies seem to reveal that much lower temperatures are characteristic of the clouds. The main content of this thesis, however, focuses on the redshift evolution of the absorbing systems producing absorption at the Lyman limit and of the amount of CIV producing CIV absorption lines. Regarding the CIV absorbers, previous predictions on the effects underlying their redshift distribution pointed to an increase with redshift of the absorbing column densities. In this thesis the first direct measurements of such column densities by profile fitting of a large number of absorption systems (73) are presented, confirming the predictions of a decrease of at least a factor of 3 between z=1.5 and z=3.0. The study on the evolution of Lyman limit absorption systems (LLSs) puts an end to previous discrepancies between the results of different groups. Both a smooth single power law dependence of the LLS number density on redshift indicating no evolution in number density for 0.4 <= z <= 4.1, and a broken power law with a rapid increase above z ~ 2.5 had been obtained with different data sets. A detailed analysis reveals here the reasons for these discrepancies and obtains the most reliable

Assessing the Ability of Vegetation Indices to Identify Shallow Subsurface Water Flow Pathways from Hyperspectral Imagery Using Machine Learning: Methodology

NASA Astrophysics Data System (ADS)

Byers, J. M.; Doctor, K.

2017-12-01

A common application of the satellite and airborne acquired hyperspectral imagery in the visible and NIR spectrum is the assessment of vegetation. Various absorption features of plants related to both water and chlorophyll content can be used to measure the vigor and access to underlying water sources of the vegetation. The typical strategy is to form hand-crafted features from the hyperspectral data cube by selecting two wavelengths to form difference or ratio images in the pixel space. The new image attempts to provide greater contrast for some feature of the vegetation. The Normalized Difference Vegetation Index (NDVI) is a widely used example formed from the ratio of differences and sums at two different wavelengths. There are dozens of these indices that are ostensibly formed using insights about the underlying physics of the spectral absorption with claims to efficacy in representing various properties of vegetation. In the language of machine learning these vegetation indices are features that can be used as a useful data representation within an algorithm. In this work we use a powerful approach from machine learning, probabilistic graphical models (PGM), to balance the competing needs of using existing hydrological classifications of terrain while finding statistically reliable features within hyperspectral data for identifying the generative process of the data. The algorithm in its simplest form is called a Naïve Bayes (NB) classifier and can be constructed in a data-driven estimation procedure of the conditional probability distributions that form the PGM. The Naïve Bayes model assumes that all vegetation indices (VI) are independent of one another given the hydrological class label. We seek to test its validity in a pilot study of detecting subsurface water flow pathways from VI. A more sophisticated PGM will also be explored called a tree-augmented NB that accounts for the probabilistic dependence between VI features. This methodology provides a

Transferability of multi- and hyperspectral optical biocrust indices

NASA Astrophysics Data System (ADS)

Rodríguez-Caballero, E.; Escribano, P.; Olehowski, C.; Chamizo, S.; Hill, J.; Cantón, Y.; Weber, B.

2017-04-01

Biological soil crusts (biocrusts) are communities of cyanobacteria, algae, microfungi, lichens and bryophytes in varying proportions, which live within or immediately on top of the uppermost millimeters of the soil in arid and semiarid regions. As biocrusts are highly relevant for ecosystem processes like carbon, nitrogen, and water cycling, a correct characterization of their spatial distribution is required. Following this objective, considerable efforts have been devoted to the identification and mapping of biocrusts using remote sensing data, and several mapping indices have been developed. However, their transferability to different regions has only rarely been tested. In this study we investigated the transferability of two multispectral indices, i.e. the Crust Index (CI) and the Biological Soil Crust Index (BSCI), and two hyperspectral indices, i.e. the Continuum Removal Crust Identification Algorithm (CRCIA) and the Crust Development Index (CDI), in three sites dominated by biocrusts, but with differences in soil and vegetation composition. Whereas multispectral indices have been important and valuable tools for first approaches to map and classify biological soil crusts, hyperspectral data and indices developed for these allowed to classify biocrusts at much higher accuracy. While multispectral indices showed Kappa (κ) values below 0.6, hyperspectral indices obtained good classification accuracy (κ ∼ 0.8) in both the study area where they had been developed and in the newly tested region. These results highlight the capability of hyperspectral sensors to identify specific absorption features related to photosynthetic pigments as chlorophyll and carotenoids, but also the limitation of multispectral information to discriminate between areas dominated by biocrusts, vegetation or bare soil. Based on these results we conclude that remote sensing offers an important and valid tool to map biocrusts. However, the spectral similarity between the main surface

External facial features modify the representation of internal facial features in the fusiform face area.

PubMed

Axelrod, Vadim; Yovel, Galit

2010-08-15

Most studies of face identity have excluded external facial features by either removing them or covering them with a hat. However, external facial features may modify the representation of internal facial features. Here we assessed whether the representation of face identity in the fusiform face area (FFA), which has been primarily studied for internal facial features, is modified by differences in external facial features. We presented faces in which external and internal facial features were manipulated independently. Our findings show that the FFA was sensitive to differences in external facial features, but this effect was significantly larger when the external and internal features were aligned than misaligned. We conclude that the FFA generates a holistic representation in which the internal and the external facial features are integrated. These results indicate that to better understand real-life face recognition both external and internal features should be included. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Visual feature integration with an attention deficit.

PubMed

Arguin, M; Cavanagh, P; Joanette, Y

1994-01-01

Treisman's feature integration theory proposes that the perception of illusory conjunctions of correctly encoded visual features is due to the failure of an attentional process. This hypothesis was examined by studying brain-damaged subjects who had previously been shown to have difficulty in attending to contralesional stimulation. These subjects exhibited a massive feature integration deficit for contralesional stimulation relative to ipsilesional displays. In contrast, both normal age-matched controls and brain-damaged subjects who did not exhibit any evidence of an attention deficit showed comparable feature integration performance with left- and right-hemifield stimulation. These observations indicate the crucial function of attention for visual feature integration in normal perception.

Absorption and Transport of Sea Cucumber Saponins from Apostichopus japonicus.

PubMed

Li, Shuai; Wang, Yuanhong; Jiang, Tingfu; Wang, Han; Yang, Shuang; Lv, Zhihua

2016-06-17

The present study is focused on the intestinal absorption of sea cucumber saponins. We determined the pharmacokinetic characteristics and bioavailability of Echinoside A and Holotoxin A₁; the findings indicated that the bioavailability of Holotoxin A₁ was lower than Echinoside A. We inferred that the differences in chemical structure between compounds was a factor that explained their different characteristics of transport across the intestine. In order to confirm the absorption characteristics of Echinoside A and Holotoxin A₁, we examined their transport across Caco-2 cell monolayer and effective permeability by single-pass intestinal perfusion. The results of Caco-2 cell model indicate that Echinoside A is transported by passive diffusion, and not influenced by the exocytosis of P-glycoprotein (P-gp, expressed in the apical side of Caco-2 monolayers as the classic inhibitor). The intestinal perfusion also demonstrated well the absorption of Echinoside A and poor absorption of Holotoxin A₁, which matched up with the result of the Caco-2 cell model. The results demonstrated our conjecture and provides fundamental information on the relationship between the chemical structure of these sea cucumber saponins and their absorption characteristics, and we believe that our findings build a foundation for the further metabolism study of sea cucumber saponins and contribute to the further clinical research of saponins.

Iodine Absorption Cells Purity Testing.

PubMed

Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

2017-01-06

This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions' spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches).

Ultraviolet absorption experiment MA-059

NASA Technical Reports Server (NTRS)

Donahue, T. M.; Hudson, R. D.; Anderson, J.; Kaufman, F.; Mcelroy, M. B.

1976-01-01

The ultraviolet absorption experiment performed during the Apollo Soyuz mission involved sending a beam of atomic oxygen and atomic nitrogen resonance radiation, strong unabsorbable oxygen and nitrogen radiation, and visual radiation, all filling the same 3 deg-wide field of view from the Apollo to the Soyuz. The radiation struck a retroreflector array on the Soyuz and was returned to a spectrometer onboard the Apollo. The density of atomic oxygen and atomic nitrogen between the two spacecraft was measured by observing the amount of resonance radiation absorbed when the line joining Apollo and Soyuz was perpendicular to their velocity with respect to the ambient atmosphere. Information concerning oxygen densities was also obtained by observation of resonantly fluorescent light. The absorption experiments for atomic oxygen and atomic nitrogen were successfully performed at a range of 500 meters, and abundant resonance fluorescence data were obtained.

Landing gear energy absorption system

NASA Technical Reports Server (NTRS)

Hansen, Christopher P. (Inventor)

1994-01-01

A landing pad system is described for absorbing horizontal and vertical impact forces upon engagement with a landing surface where circumferentially arranged landing struts respectively have a clevis which receives a slidable rod member and where the upper portion of a slidable rod member is coupled to the clevis by friction washers which are force fit onto the rod member to provide for controlled constant force energy absorption when the rod member moves relative to the clevis. The lower end of the friction rod is pivotally attached by a ball and socket to a support plate where the support plate is arranged to slide in a transverse direction relative to a housing which contains an energy absorption material for absorbing energy in a transverse direction.

Photodetector with enhanced light absorption

DOEpatents

Kane, James

1985-01-01

A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

Thermal Analysis of Unusual Local-scale Features on the Surface of Vesta

NASA Technical Reports Server (NTRS)

Tosi, F.; Capria, M. T.; DeSanctis, M. C.; Capaccioni, F.; Palomba, E.; Zambon, F.; Ammannito, E.; Blewett, D. T.; Combe, J.-Ph.; Denevi, B. W.;

Highly Photostable Near-Infrared Fluorescent pH Indicators and Sensors Based on BF2-Chelated Tetraarylazadipyrromethene Dyes

PubMed Central

2012-01-01

In this study, a series of new BF2-chelated tetraarylazadipyrromethane dyes are synthesized and are shown to be suitable for the preparation of on/off photoinduced electron transfer modulated fluorescent sensors. The new indicators are noncovalently entrapped in polyurethane hydrogel D4 and feature absorption maxima in the range 660–710 nm and fluorescence emission maxima at 680–740 nm. Indicators have high molar absorption coefficients of ∼80 000 M–1 cm–1, good quantum yields (up to 20%), excellent photostability and low cross-sensitivity to the ionic strength. pKa values of indicators are determined from absorbance and fluorescence measurements and range from 7 to 11, depending on the substitution pattern of electron-donating and -withdrawing functionalities. Therefore, the new indicators are suitable for exploitation and adaptation in a diverse range of analytical applications. Apparent pKa values in sensor films derived from fluorescence data show 0.5–1 pH units lower values in comparison with those derived from the absorption data due to Förster resonance energy transfer from protonated to deprotonated form. A dual-lifetime referenced sensor is prepared, and application for monitoring of pH in corals is demonstrated. PMID:22738322

Highly photostable near-infrared fluorescent pH indicators and sensors based on BF2-chelated tetraarylazadipyrromethene dyes.

PubMed

Jokic, Tijana; Borisov, Sergey M; Saf, Robert; Nielsen, Daniel A; Kühl, Michael; Klimant, Ingo

2012-08-07

In this study, a series of new BF(2)-chelated tetraarylazadipyrromethane dyes are synthesized and are shown to be suitable for the preparation of on/off photoinduced electron transfer modulated fluorescent sensors. The new indicators are noncovalently entrapped in polyurethane hydrogel D4 and feature absorption maxima in the range 660-710 nm and fluorescence emission maxima at 680-740 nm. Indicators have high molar absorption coefficients of ~80,000 M(-1) cm(-1), good quantum yields (up to 20%), excellent photostability and low cross-sensitivity to the ionic strength. pK(a) values of indicators are determined from absorbance and fluorescence measurements and range from 7 to 11, depending on the substitution pattern of electron-donating and -withdrawing functionalities. Therefore, the new indicators are suitable for exploitation and adaptation in a diverse range of analytical applications. Apparent pK(a) values in sensor films derived from fluorescence data show 0.5-1 pH units lower values in comparison with those derived from the absorption data due to Förster resonance energy transfer from protonated to deprotonated form. A dual-lifetime referenced sensor is prepared, and application for monitoring of pH in corals is demonstrated.

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.

Experience improves feature extraction in Drosophila.

PubMed

Peng, Yueqing; Xi, Wang; Zhang, Wei; Zhang, Ke; Guo, Aike

2007-05-09

Previous exposure to a pattern in the visual scene can enhance subsequent recognition of that pattern in many species from honeybees to humans. However, whether previous experience with a visual feature of an object, such as color or shape, can also facilitate later recognition of that particular feature from multiple visual features is largely unknown. Visual feature extraction is the ability to select the key component from multiple visual features. Using a visual flight simulator, we designed a novel protocol for visual feature extraction to investigate the effects of previous experience on visual reinforcement learning in Drosophila. We found that, after conditioning with a visual feature of objects among combinatorial shape-color features, wild-type flies exhibited poor ability to extract the correct visual feature. However, the ability for visual feature extraction was greatly enhanced in flies trained previously with that visual feature alone. Moreover, we demonstrated that flies might possess the ability to extract the abstract category of "shape" but not a particular shape. Finally, this experience-dependent feature extraction is absent in flies with defective MBs, one of the central brain structures in Drosophila. Our results indicate that previous experience can enhance visual feature extraction in Drosophila and that MBs are required for this experience-dependent visual cognition.

Observational Evidence Linking Interstellar UV Absorption to PAH Molecules

NASA Astrophysics Data System (ADS)

Blasberger, Avi; Behar, Ehud; Perets, Hagai B.; Brosch, Noah; Tielens, Alexander G. G. M.

2017-02-01

The 2175 Å UV extinction feature was discovered in the mid-1960s, yet its physical origin remains poorly understood. One suggestion is absorption by polycyclic aromatic hydrocarbon (PAH) molecules, which is supported by theoretical molecular structure computations and by laboratory experiments. PAHs are positively detected by their 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 μm IR emission bands, which are specified by their modes of vibration. A definitive empirical link between the 2175 Å UV extinction and the IR PAH emission bands, however, is still missing. We present a new sample of hot stars that have both 2175 Å absorption and IR PAH emission. We find significant shifts of the central wavelength of the UV absorption feature, up to 2350 Å, but predominantly in stars that also have IR PAH emission. These UV shifts depend on stellar temperature in a fashion that is similar to the shifts of the 6.2 and 7.7 μm IR PAH bands, that is, the features are increasingly more redshifted as the stellar temperature decreases, but only below ˜15 kK. Above 15 kK both UV and IR features retain their nominal values. Moreover, we find a suggestive correlation between the UV and IR shifts. We hypothesize that these similar dependences of both the UV and IR features on stellar temperature hint at a common origin of the two in PAH molecules and may establish the missing link between the UV and IR observations. We further suggest that the shifts depend on molecular size, and that the critical temperature of ˜15 kK above which no shifts are observed is related to the onset of UV-driven hot-star winds and their associated shocks.

Surface Composition and Physical Mixture State of the Regoliths of Outer Solar System Satellites: The Role of Scattering and Absorption by the non-Ice Components and Implications for Rayleigh Absorption and Rayleigh Scattering

NASA Astrophysics Data System (ADS)

Clark, R. N.; Perlman, Z. S.; Pearson, N.; Hendrix, A. R.; Cuzzi, J. N.; Cruikshank, D. P.; Bradley, E. T.; Filacchione, G.; Nicholson, P. D.; Hedman, M. M.; Brown, R. H.; Buratti, B. J.; Baines, K. H.; Sotin, C.; Nelson, R. M.

2014-12-01

Many outer Solar System satellites have surfaces dominated by water ice and a mysterious material(s) causing strong visible to ultraviolet absorption along with trace other compounds with infrared absorptions, including CO2 and organics. Various mechanisms have been proposed for the UV absorber, including tholins, iron oxides, and nano-sized metallic iron particles (e.g. see Clark et al., 2012, Icarus v218 p831, and references therein). We have constructed extensive laboratory analog measurements and radiative transfer modeling of the materials and scattering conditions that can contribute to the optical properties seen on outer Solar System satellites. We have successfully modeled Rayleigh absorption and Rayleigh scattering to produce spectral shapes typical of those seen in spectra of icy Solar System satellites, including those in the Saturn system observed with the Cassini UVIS and VIMS instruments. While it is easy to create these absorptions with radiative transfer modeling, it has been more difficult to do with laboratory analogs. We are finding that laboratory analogs refine and restricts the possible mixing states of the UV absorber in icy satellite surfaces. We have found that just because a particle is highly absorbing, as in metallic iron, if the particle is not embedded in another matrix, scattering will dominate over absorption and Rayleigh absorption will not be observed. Further, the closer the indices of refraction match between the absorbing particle and the matrix, there will be less scattering and more absorption will occur. But we have also found this to be true with other absorbing material, like Tholins. It is very difficult to obtain the very low reflectances observed in the UV in icy satellite spectra using traditional intimate mixtures, as scattering and first surface reflections contribute significantly to the reflectance. The solution, both from radiative transfer modeling and laboratory analogs point to embedded absorbing materials. For

Study of moisture absorption by an organoplastic

NASA Astrophysics Data System (ADS)

Aniskevich, A. N.; Yanson, Yu. O.

1991-07-01

A complex experimental study of the state of sorbed moisture in a unidirectionally reinforced organoplastic was conducted. The methods of TG, DSC, DTA, and NMR showed that moisture absorption in OP is reversible up to 8%, the sorbed moisture does not crystallize in the temperature range from -70 to 0 °C, it is finely dispersely distributed and is in the strongly and weakly bound state, and there is almost no free moisture. The results of the sorption experiments conducted on OP and its structural components: microplastic and EDT-10 binder, in a wide range of temperature-humidity conditions and the data from physical studies showed that moisture absorption in the materials basically takes place by diffusion and is satisfactorily described by a phenomenological model based on the Fick equation. A method of accelerated determination of the sorption characteristics of anisotropic composite materials was developed, using the introduced concept of the fictitious diffusion coefficient and the extrapolation method of determining the limiting moisture content. The features of migration of moisture on the interface in a multiphase system were investigated, and the possibility of successive calculation estimation of the sorption characteristics of an organoplastic at different structural levels was demonstrated: components—unidirectionally reinforced composite—model laminated article. The tested phenomenological model of the sorption process and the experimentally obtained values of the characteristics of the material were the basis for a method of calculation determination of the resource of moisture-proofing properties of a model multilayer article of CM in nonstationary external conditions.

Histopathological features of Proteus syndrome.

PubMed

Hoey, S E H; Eastwood, D; Monsell, F; Kangesu, L; Harper, J I; Sebire, N J

2008-05-01

Proteus syndrome is a rare, sporadic overgrowth disorder for which the underlying genetic defect remains unknown. Although the clinical course is well-described there is no systematic histopathological description of the lesional pathology. To describe the histopathological features encountered in a series of patients with Proteus syndrome from a single centre. Patients with Proteus syndrome who had undergone therapeutic surgical resection or biopsy were identified from a database and the histopathological findings were reviewed, with particular regard to descriptive features of the underlying tissue abnormality. There were 18 surgical specimens from nine patients, median age 4 years (range 1-9), classified into four main categories: soft-tissue swellings (lipomatous lesions), vascular anomalies (vascular malformation and haemangioma), macrodactyly (hamartomatous overgrowth) and others (sebaceous naevus and nonspecific features). In all cases, the clinical features of overgrowth were due to increased amounts of disorganized tissue, indicating a hamartomatous-type defect in which normal tissue constituents were present, but with an abnormal distribution and architecture. Vascular malformations represented a prominent category of lesions, accounting for 50% of the specimens, predominantly comprising lymphatic and lymphovascular malformations. No malignancy or cytological atypia was identified in any case. The histopathological features of lesions resected from children with Proteus syndrome predominantly include hamartomatous mixed connective tissue lesions, benign neoplasms such as lipomata, and lymphatic-rich vascular malformations.

Detectability of cold streams into high-redshift galaxies by absorption lines

NASA Astrophysics Data System (ADS)

Goerdt, Tobias; Dekel, Avishai; Sternberg, Amiel; Gnat, Orly; Ceverino, Daniel

2012-08-01

Cold gas streaming along the dark matter filaments of the cosmic web is predicted to be the major source of fuel for disc buildup, violent disc instability and star formation in massive galaxies at high redshift. We investigate to what extent such cold gas is detectable in the extended circumgalactic environment of galaxies via Lyα absorption and selected low-ionization metal absorption lines. We model the expected absorption signatures using high-resolution zoom-in adaptive mesh refinement cosmological simulations. In the post-processing, we distinguish between self-shielded gas and unshielded gas. In the self-shielded gas, which is optically thick to Lyman continuum radiation, we assume pure collisional ionization for species with an ionization potential greater than 13.6 eV. In the optically-thin, unshielded gas, these species are also photoionized by the metagalactic radiation. In addition to absorption of radiation from background quasars, we compute the absorption line profiles of radiation emitted by the galaxy at the centre of the same halo. We predict the strength of the absorption signal for individual galaxies without stacking. We find that the Lyα absorption profiles produced by the streams are consistent with observations of absorption and emission Lyα profiles in high-redshift galaxies. Due to the low metallicities in the streams, and their low covering factors, the metal absorption features are weak and difficult to detect.

Piezoelectric-tuned microwave cavity for absorption spectrometry

DOEpatents

Leskovar, Branko; Buscher, Harold T.; Kolbe, William F.

1978-01-01

Gas samples are analyzed for pollutants in a microwave cavity that is provided with two highly polished walls. One wall of the cavity is mechanically driven with a piezoelectric transducer at a low frequency to tune the cavity over a band of microwave frequencies in synchronism with frequency modulated microwave energy applied to the cavity. Absorption of microwave energy over the tuned frequencies is detected, and energy absorption at a particular microwave frequency is an indication of a particular pollutant in the gas sample.

Hyperspectral Features of Oil-Polluted Sea Ice and the Response to the Contamination Area Fraction

PubMed Central

Li, Ying; Liu, Chengyu; Xie, Feng

2018-01-01

Researchers have studied oil spills in open waters using remote sensors, but few have focused on extracting reflectance features of oil pollution on sea ice. An experiment was conducted on natural sea ice in Bohai Bay, China, to obtain the spectral reflectance of oil-contaminated sea ice. The spectral absorption index (SAI), spectral peak height (SPH), and wavelet detail coefficient (DWT d5) were calculated using stepwise multiple linear regression. The reflectances of some false targets were measured and analysed. The simulated false targets were sediment, iron ore fines, coal dust, and the melt pool. The measured reflectances were resampled using five common sensors (GF-2, Landsat8-OLI, Sentinel3-OLCI, MODIS, and AVIRIS). Some significant spectral features could discriminate between oil-polluted and clean sea ice. The indices correlated well with the oil area fractions. All of the adjusted R2 values exceeded 0.9. The SPH model1, based on spectral features at 507–670 and 1627–1746 nm, displayed the best fitting. The resampled data indicated that these multi-spectral and hyper-spectral sensors could be used to detect crude oil on the sea ice if the effect of noise and spatial resolution are neglected. The spectral features and their identified changes may provide reference on sensor design and band selection. PMID:29342945

Strong water absorption in the dayside emission spectrum of the planet HD 189733b.

PubMed

Grillmair, Carl J; Burrows, Adam; Charbonneau, David; Armus, Lee; Stauffer, John; Meadows, Victoria; van Cleve, Jeffrey; von Braun, Kaspar; Levine, Deborah

2008-12-11

Recent observations of the extrasolar planet HD 189733b did not reveal the presence of water in the emission spectrum of the planet. Yet models of such 'hot-Jupiter' planets predict an abundance of atmospheric water vapour. Validating and constraining these models is crucial to understanding the physics and chemistry of planetary atmospheres in extreme environments. Indications of the presence of water in the atmosphere of HD 189733b have recently been found in transmission spectra, where the planet's atmosphere selectively absorbs the light of the parent star, and in broadband photometry. Here we report the detection of strong water absorption in a high-signal-to-noise, mid-infrared emission spectrum of the planet itself. We find both a strong downturn in the flux ratio below 10 microm and discrete spectral features that are characteristic of strong absorption by water vapour. The differences between these and previous observations are significant and admit the possibility that predicted planetary-scale dynamical weather structures may alter the emission spectrum over time. Models that match the observed spectrum and the broadband photometry suggest that heat redistribution from the dayside to the nightside is weak. Reconciling this with the high nightside temperature will require a better understanding of atmospheric circulation or possible additional energy sources.

An x-ray absorption spectroscopy study of Ni-Mn-Ga shape memory alloys.

PubMed

Sathe, V G; Dubey, Aditi; Banik, Soma; Barman, S R; Olivi, L

2013-01-30

The austenite to martensite phase transition in Ni-Mn-Ga ferromagnetic shape memory alloys was studied by extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) spectroscopy. The spectra at all the three elements', namely, Mn, Ga and Ni, K-edges in several Ni-Mn-Ga samples (with both Ni and Mn excess) were analyzed at room temperature and low temperatures. The EXAFS analysis suggested a displacement of Mn and Ga atoms in opposite direction with respect to the Ni atoms when the compound transforms from the austenite phase to the martensite phase. The first coordination distances around the Mn and Ga atoms remained undisturbed on transition, while the second and subsequent shells showed dramatic changes indicating the presence of a modulated structure. The Mn rich compounds showed the presence of antisite disorder of Mn and Ga. The XANES results showed remarkable changes in the unoccupied partial density of states corresponding to Mn and Ni, while the electronic structure of Ga remained unperturbed across the martensite transition. The post-edge features in the Mn K-edge XANES spectra changed from a double peak like structure to a flat peak like structure upon phase transition. The study establishes strong correlation between the crystal structure and the unoccupied electronic structure in these shape memory alloys.

Ultrafast transient absorption studies of hematite nanoparticles: the effect of particle shape on exciton dynamics.

PubMed

Fitzmorris, Bob C; Patete, Jonathan M; Smith, Jacqueline; Mascorro, Xiomara; Adams, Staci; Wong, Stanislaus S; Zhang, Jin Z

2013-10-01

Much progress has been made in using hematite (α-Fe2 O3 ) as a potentially practical and sustainable material for applications such as solar-energy conversion and photoelectrochemical (PEC) water splitting; however, recent studies have shown that the performance can be limited by a very short charge-carrier diffusion length or exciton lifetime. In this study, we performed ultrafast studies on hematite nanoparticles of different shapes to determine the possible influence of particle shape on the exciton dynamics. Nanorice, multifaceted spheroidal nanoparticles, faceted nanocubes, and faceted nanorhombohedra were synthesized and characterized by using SEM and XRD techniques. Their exciton dynamics were investigated by using femtosecond transient absorption (TA) spectroscopy. Although the TA spectral features differ for the four samples studied, their decay profiles are similar, which can be fitted with time constants of 1-3 ps, approximately 25 ps, and a slow nanosecond component extending beyond the experimental time window that was measured (2 ns). The results indicate that the overall exciton lifetime is weakly dependent on the shape of the hematite nanoparticles, even though the overall optical absorption and scattering are influenced by the particle shape. This study suggests that other strategies need to be developed to increase the exciton lifetime or to lengthen the exciton diffusion length in hematite nanostructures. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Absorption characteristics of forest fire particulate matter

Treesearch

E.M. Patterson; Charles K. McMahon

1984-01-01

Abstract. Absorption properties of smokes from laboratory fires that represent prescription hums in the Southern states have been quantified to relate variations in measured absorption parameters to variation in fire conditions and to estimate emission factors for elemental carbon. Results showed significant differences in absorption of the smoke...

The widetilde{A}←widetilde{X} ABSORPTION SPECTRUM OF 2-NITROOXYBUTYL PEROXY RADICAL

NASA Astrophysics Data System (ADS)

Eddingsaas, Nathan; Takematsu, Kana; Okumura, Mitchio

2009-06-01

The nitrate radical is an important atmospheric oxidant in the nighttime sky. Nitrate radicals react by addition to alkenes, and in the presence of oxygen form nitrooxyalkyl peroxy radicals. The peroxy radical formed from the reaction of 2-butene, nitrate radical, and oxygen was detected by cavity ringdown spectroscopy (CRDS) via its widetilde{A}←widetilde{X} electronic absorption spectrum. The widetilde{A}←widetilde{X} electronic transition is a bound-bound transition with enough structure to distinguish between different peroxy radicals as well as different conformers of the same peroxy radical. Two conformers of the nitrooxybutyl peroxy radical have been observed; the absorption features are red shifted from the same absorption features of sec-butyl peroxy radical. Calculations on the structure of nitrooxyalkyl peroxy radicals and general trends of the position of the widetilde{A}←widetilde{X} absorption transitions have also been performed and compared to those of unsubstituted peroxy radicals.

Absorption-enhancing effects of gemini surfactant on the intestinal absorption of poorly absorbed hydrophilic drugs including peptide and protein drugs in rats.

PubMed

Alama, Tammam; Kusamori, Kosuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

2016-02-29

In general, the intestinal absorption of small hydrophilic molecules and macromolecules like peptides, after oral administration is very poor. Absorption enhancers are considered to be one of the most promising agents to enhance the intestinal absorption of drugs. In this research, we focused on a gemini surfactant, a new type of absorption enhancer. The intestinal absorption of drugs, with or without sodium dilauramidoglutamide lysine (SLG-30), a gemini surfactant, was examined by an in situ closed-loop method in rats. The intestinal absorption of 5(6)-carboxyfluorescein (CF) and fluorescein isothiocyanate-dextrans (FDs) was significantly enhanced in the presence of SLG-30, such effect being reversible. Furthermore, the calcium levels in the plasma significantly decreased when calcitonin was co-administered with SLG-30, suggestive of the increased intestinal absorption of calcitonin. In addition, no significant increase in the of lactate dehydrogenase (LDH) activity or in protein release from the intestinal epithelium was observed in the presence of SLG-30, suggestive of the safety of this compound. These findings indicate that SLG-30 is an effective absorption-enhancer for improving the intestinal absorption of poorly absorbed drugs, without causing serious damage to the intestinal epithelium. Copyright © 2015 Elsevier B.V. All rights reserved.

The Development of New Solar Indices for use in Thermospheric Density Modeling

NASA Technical Reports Server (NTRS)

Tobiska, W. Kent; Bouwer, S. Dave; Bowman, Bruce R.

2006-01-01

New solar indices have been developed to improve thermospheric density modeling for research and operational purposes. Out of 11 new and 4 legacy indices and proxies, we have selected three (F10.7, S10.7, and M10.7) for use in the new JB2006 empirical thermospheric density model. In this work, we report on the development of these solar irradiance indices. The rationale for their use, their definitions, and their characteristics, including the ISO 21348 spectral category and sub-category, wavelength range, solar source temperature region, solar source feature, altitude region of terrestrial atmosphere absorption at unit optical depth, and terrestrial atmosphere thermal processes in the region of maximum energy absorption, are described. We also summarize for each solar index, the facility and instrument(s) used to observe the solar emission, the time frame over which the data exist, the measurement cadence, the data latency, and the research as well as operational availability. The new solar indices are provided in forecast (http://SpaceWx.com) as well as real-time and historical (http://sol.spacenvironment.net/jb2006/) time frames. We describe the forecast methodology, compare results with actual data for active and quiet solar conditions, and compare improvements in F10.7 forecasting with legacy High Accuracy Satellite Drag Model (HASDM) and NOAA SEC forecasts.

Search for correlated UV and x ray absorption of NGC 3516

NASA Technical Reports Server (NTRS)

Martin, Christopher; Halpern, Jules P.; Kolman, Michiel

1991-01-01

NGC 3516, a low-luminosity Seyfert galaxy, is one of a small fraction of Seyfert galaxies that exhibit broad absorption in a resonance line. In order to determine whether the UV and x ray absorption in NGC 3516 are related, 5 IUE observations were obtained, quasi-simultaneously with 4 Ginga observations. The results are presented and discussed. The following subject areas are covered: short-term UV variability; emission lines; galactic absorption lines; the C IV, N V, and Si IV absorption features; lower limit on the carbon column density; estimate of the distance from the absorber to the continuum source; variability in the continuum and absorption; a comparison with BAL QSO's; and the x ray-UV connection.

Structural parameter effect of porous material on sound absorption performance of double-resonance material

NASA Astrophysics Data System (ADS)

Fan, C.; Tian, Y.; Wang, Z. Q.; Nie, J. K.; Wang, G. K.; Liu, X. S.

2017-06-01

In view of the noise feature and service environment of urban power substations, this paper explores the idea of compound impedance, fills some porous sound-absorption material in the first resonance cavity of the double-resonance sound-absorption material, and designs a new-type of composite acoustic board. We conduct some acoustic characterizations according to the standard test of impedance tube, and research on the influence of assembly order, the thickness and area density of the filling material, and back cavity on material sound-absorption performance. The results show that the new-type of acoustic board consisting of aluminum fibrous material as inner structure, micro-porous board as outer structure, and polyester-filled space between them, has good sound-absorption performance for low frequency and full frequency noise. When the thickness, area density of filling material and thickness of back cavity increase, the sound absorption coefficient curve peak will move toward low frequency.

Dataset used to improve liquid water absorption models in the microwave

DOE Data Explorer

Turner, David

2015-12-14

Two datasets, one a compilation of laboratory data and one a compilation from three field sites, are provided here. These datasets provide measurements of the real and imaginary refractive indices and absorption as a function of cloud temperature. These datasets were used in the development of the new liquid water absorption model that was published in Turner et al. 2015.

Simultaneous Atomic Absorption Spectrometry for Cadmium and Lead Determination in Wastewater: A Laboratory Exercise

ERIC Educational Resources Information Center

Correia, Paulo R. M.; Oliveira, Pedro V.

2004-01-01

The simultaneous determination of cadmium and lead by multi-element atomic absorption spectrometry with electrochemical atomization is proposed by employing a problem-based approach. The reports indicate that the students assimilated the principles of the simultaneous atomic absorption spectrometry (SIMAAS), the role of the chemical modifier, the…

Advanced regenerative absorption refrigeration cycles

DOEpatents

Dao, Kim

1990-01-01

Multi-effect regenerative absorption cycles which provide a high coefficient of performance (COP) at relatively high input temperatures. An absorber-coupled double-effect regenerative cycle (ADR cycle) (10) is provided having a single-effect absorption cycle (SEA cycle) (11) as a topping subcycle and a single-effect regenerative absorption cycle (1R cycle) (12) as a bottoming subcycle. The SEA cycle (11) includes a boiler (13), a condenser (21), an expansion device (28), an evaporator (31), and an absorber (40), all operatively connected together. The 1R cycle (12) includes a multistage boiler (48), a multi-stage resorber (51), a multisection regenerator (49) and also uses the condenser (21), expansion device (28) and evaporator (31) of the SEA topping subcycle (11), all operatively connected together. External heat is applied to the SEA boiler (13) for operation up to about 500 degrees F., with most of the high pressure vapor going to the condenser (21) and evaporator (31) being generated by the regenerator (49). The substantially adiabatic and isothermal functioning of the SER subcycle (12) provides a high COP. For higher input temperatures of up to 700 degrees F., another SEA cycle (111) is used as a topping subcycle, with the absorber (140) of the topping subcycle being heat coupled to the boiler (13) of an ADR cycle (10). The 1R cycle (12) itself is an improvement in that all resorber stages (50b-f) have a portion of their output pumped to boiling conduits (71a-f) through the regenerator (49), which conduits are connected to and at the same pressure as the highest pressure stage (48a) of the 1R multistage boiler (48).

Birefringence and anisotropic optical absorption in porous silicon

SciTech Connect

Efimova, A. I., E-mail: efimova@vega.phys.msu.ru; Krutkova, E. Yu.; Golovan', L. A.

2007-10-15

The refractive indices and the coefficients of optical absorption by free charge carriers and local vibrations in porous silicon (por-Si) films, comprising nanometer-sized silicon residues (nanocrystals) separated by nanometer-sized pores (nanopores) formed in the course of electrochemical etching of the initial single crystal silicon, have been studied by polarization-resolved IR absorption spectroscopy techniques. It is shown that the birefringence observed in por-Si is related to the anisotropic shapes of nanocrystals and nanopores, while the anisotropy (dichroism) of absorption by the local vibrational modes is determined predominantly by the microrelief of the surface of nanocrystals. It is demonstrated that silicon-hydrogen surfacemore » bonds in nanocrystals can be restored by means of selective hydrogen thermodesorption with the formation of a considerable number of H-terminated surface Si-Si dimers.« less

Diabetes regulates fructose absorption through thioredoxin-interacting protein.

PubMed

Dotimas, James R; Lee, Austin W; Schmider, Angela B; Carroll, Shannon H; Shah, Anu; Bilen, Julide; Elliott, Kayla R; Myers, Ronald B; Soberman, Roy J; Yoshioka, Jun; Lee, Richard T

2016-10-11

Metabolic studies suggest that the absorptive capacity of the small intestine for fructose is limited, though the molecular mechanisms controlling this process remain unknown. Here we demonstrate that thioredoxin-interacting protein (Txnip), which regulates glucose homeostasis in mammals, binds to fructose transporters and promotes fructose absorption by the small intestine. Deletion of Txnip in mice reduced fructose transport into the peripheral bloodstream and liver, as well as the severity of adverse metabolic outcomes resulting from long-term fructose consumption. We also demonstrate that fructose consumption induces expression of Txnip in the small intestine. Diabetic mice had increased expression of Txnip in the small intestine as well as enhanced fructose uptake and transport into the hepatic portal circulation. The deletion of Txnip in mice abolished the diabetes-induced increase in fructose absorption. Our results indicate that Txnip is a critical regulator of fructose metabolism and suggest that a diabetic state can promote fructose uptake.

Dielectric Characteristics and Microwave Absorption of Graphene Composite Materials

PubMed Central

Rubrice, Kevin; Castel, Xavier; Himdi, Mohamed; Parneix, Patrick

2016-01-01

Nowadays, many types of materials are elaborated for microwave absorption applications. Carbon-based nanoparticles belong to these types of materials. Among these, graphene presents some distinctive features for electromagnetic radiation absorption and thus microwave isolation applications. In this paper, the dielectric characteristics and microwave absorption properties of epoxy resin loaded with graphene particles are presented from 2 GHz to 18 GHz. The influence of various parameters such as particle size (3 µm, 6–8 µm, and 15 µm) and weight ratio (from 5% to 25%) are presented, studied, and discussed. The sample loaded with the smallest graphene size (3 µm) and the highest weight ratio (25%) exhibits high loss tangent (tanδ = 0.36) and a middle dielectric constant ε′ = 12–14 in the 8–10 GHz frequency range. As expected, this sample also provides the highest absorption level: from 5 dB/cm at 4 GHz to 16 dB/cm at 18 GHz. PMID:28773948

Improvement of depth resolution on photoacoustic imaging using multiphoton absorption

NASA Astrophysics Data System (ADS)

Yamaoka, Yoshihisa; Fujiwara, Katsuji; Takamatsu, Tetsuro

2007-07-01

Commercial imaging systems, such as computed tomography and magnetic resonance imaging, are frequently used powerful tools for observing structures deep within the human body. However, they cannot precisely visualized several-tens micrometer-sized structures for lack of spatial resolution. In this presentation, we propose photoacoustic imaging using multiphoton absorption technique to generate ultrasonic waves as a means of improving depth resolution. Since the multiphoton absorption occurs at only the focus point and the employed infrared pulses deeply penetrate living tissues, it enables us to extract characteristic features of structures embedded in the living tissue. When nanosecond pulses from a 1064-nm Nd:YAG laser were focused on Rhodamine B/chloroform solution (absorption peak: 540 nm), the peak intensity of the generated photoacoustic signal was proportional to the square of the input pulse energy. This result shows that the photoacoustic signals can be induced by the two-photon absorption of infrared nanosecond pulse laser and also can be detected by a commercial low-frequency MHz transducer. Furthermore, in order to evaluate the depth resolution of multiphoton-photoacoustic imaging, we investigated the dependence of photoacoustic signal on depth position using a 1-mm-thick phantom in a water bath. We found that the depth resolution of two-photon photoacoustic imaging (1064 nm) is greater than that of one-photon photoacoustic imaging (532 nm). We conclude that evolving multiphoton-photoacoustic imaging technology renders feasible the investigation of biomedical phenomena at the deep layer in living tissue.

A novel multiplex absorption spectrometer for time-resolved studies

NASA Astrophysics Data System (ADS)

Lewis, Thomas; Heard, Dwayne E.; Blitz, Mark A.

2018-02-01

A Time-Resolved Ultraviolet/Visible (UV/Vis) Absorption Spectrometer (TRUVAS) has been developed that can simultaneously monitor absorption at all wavelengths between 200 and 800 nm with millisecond time resolution. A pulsed photolysis laser (KrF 248 nm) is used to initiate chemical reactions that create the target species. The absorption signals from these species evolve as the composition of the gas in the photolysis region changes over time. The instrument can operate at pressures over the range ˜10-800 Torr and can measure time-resolved absorbances <10-4 in the UV (300 nm) and even lower in the visible (580 nm) 2.3 × 10-5, with the peak of sensitivity at ˜500 nm. The novelty of this setup lies in the arrangement of the multipass optics. Although appearing similar to other multipass optical systems (in particular the Herriott cell), there are fundamental differences, most notably the ability to adjust each mirror to maximise the overlap between the probe beam and the photolysis laser. Another feature which aids the sensitivity and versatility of the system is the use of 2 high-throughput spectrographs coupled with sensitive line-array CCDs, which can measure absorbance from ˜200 to 800 nm simultaneously. The capability of the instrument is demonstrated via measurements of the absorption spectrum of the peroxy radical, HOCH2CH2O2, and its self-reaction kinetics.

Physiologically Based Pharmacokinetic and Absorption Modeling for Osmotic Pump Products.

PubMed

Ni, Zhanglin; Talattof, Arjang; Fan, Jianghong; Tsakalozou, Eleftheria; Sharan, Satish; Sun, Dajun; Wen, Hong; Zhao, Liang; Zhang, Xinyuan

2017-07-01

Physiologically based pharmacokinetic (PBPK) and absorption modeling approaches were employed for oral extended-release (ER) drug products based on an osmotic drug delivery system (osmotic pumps). The purpose was to systemically evaluate the in vivo relevance of in vitro dissolution for this type of formulation. As expected, in vitro dissolution appeared to be generally predictive of in vivo PK profiles, because of the unique feature of this delivery system that the in vitro and in vivo release of osmotic pump drug products is less susceptible to surrounding environment in the gastrointestinal (GI) tract such as pH, hydrodynamic, and food effects. The present study considered BCS (Biopharmaceutics Classification System) class 1, 2, and 3 drug products with half-lives ranging from 2 to greater than 24 h. In some cases, the colonic absorption models needed to be adjusted to account for absorption in the colon. C max (maximum plasma concentration) and AUCt (area under the concentration curve) of the studied drug products were sensitive to changes in colon permeability and segmental GI transit times in a drug product-dependent manner. While improvement of the methodology is still warranted for more precise prediction (e.g., colonic absorption and dynamic movement in the GI tract), the results from the present study further emphasized the advantage of using PBPK modeling in addressing product-specific questions arising from regulatory review and drug development.

NEUTRON ABSORPTION AND SHIELDING DEVICE

DOEpatents

Axelrad, I.R.

1960-06-21

A neutron absorption and shielding device is described which is adapted for mounting in a radiation shielding wall surrounding a radioactive area through which instrumentation leads and the like may safely pass without permitting gamma or neutron radiation to pass to the exterior. The shielding device comprises a container having at least one nonrectilinear tube or passageway means extending therethrough, which is adapted to contain instrumentation leads or the like, a layer of a substance capable of absorbing gamma rays, and a solid resinous composition adapted to attenuate fast-moving neutrons and capture slow- moving or thermal neutrons.

Microwave Absorption Characteristics of Tire

NASA Astrophysics Data System (ADS)

Zhang, Yuzhe; Hwang, Jiann-Yang; Peng, Zhiwei; Andriese, Matthew; Li, Bowen; Huang, Xiaodi; Wang, Xinli

The recycling of waste tires has been a big environmental problem. About 280 million waste tires are produced annually in the United States and more than 2 billion tires are stockpiled, which cause fire hazards and health issues. Tire rubbers are insoluble elastic high polymer materials. They are not biodegradable and may take hundreds of years to decompose in the natural environment. Microwave irradiation can be a thermal processing method for the decomposition of tire rubbers. In this study, the microwave absorption properties of waste tire at various temperatures are characterized to determine the conditions favorable for the microwave heating of waste tires.

Carbon Dioxide Absorption Heat Pump

NASA Technical Reports Server (NTRS)

Jones, Jack A. (Inventor)

2002-01-01

A carbon dioxide absorption heat pump cycle is disclosed using a high pressure stage and a super-critical cooling stage to provide a non-toxic system. Using carbon dioxide gas as the working fluid in the system, the present invention desorbs the CO2 from an absorbent and cools the gas in the super-critical state to deliver heat thereby. The cooled CO2 gas is then expanded thereby providing cooling and is returned to an absorber for further cycling. Strategic use of heat exchangers can increase the efficiency and performance of the system.

Microwave measurements of the absolute values of absorption by water vapour in the atmosphere.

PubMed

Hogg, D C; Guiraud, F O

1979-05-31

MEASUREMENT of the absolute value of absorption by water vapour at microwave frequencies is difficult because the effect is so small. Far in the wings of the absorption lines, in the so-called 'windows' of the spectrum, it is especially difficult to achieve high accuracy in the free atmosphere. But it is in these windows that the behaviour of the absorption is important from both applied and scientific points of view. Satellite communications, remote sensing of the atmosphere, and radioastronomy, are all influenced by this behaviour. Measurements on an Earth-space path are reported here; the results indicate a nonlinear relationship between absorption and water-vapour content.

Tunneling induced absorption with competing Nonlinearities

PubMed Central

Peng, Yandong; Yang, Aihong; Xu, Yan; Wang, Peng; Yu, Yang; Guo, Hongju; Ren, Tingqi

2016-01-01

We investigate tunneling induced nonlinear absorption phenomena in a coupled quantum-dot system. Resonant tunneling causes constructive interference in the nonlinear absorption that leads to an increase of more than an order of magnitude over the maximum absorption in a coupled quantum dot system without tunneling. Resonant tunneling also leads to a narrowing of the linewidth of the absorption peak to a sublinewidth level. Analytical expressions show that the enhanced nonlinear absorption is largely due to the fifth-order nonlinear term. Competition between third- and fifth-order nonlinearities leads to an anomalous dispersion of the total susceptibility. PMID:27958303

Tunneling induced absorption with competing Nonlinearities.

PubMed

Peng, Yandong; Yang, Aihong; Xu, Yan; Wang, Peng; Yu, Yang; Guo, Hongju; Ren, Tingqi

2016-12-13

We investigate tunneling induced nonlinear absorption phenomena in a coupled quantum-dot system. Resonant tunneling causes constructive interference in the nonlinear absorption that leads to an increase of more than an order of magnitude over the maximum absorption in a coupled quantum dot system without tunneling. Resonant tunneling also leads to a narrowing of the linewidth of the absorption peak to a sublinewidth level. Analytical expressions show that the enhanced nonlinear absorption is largely due to the fifth-order nonlinear term. Competition between third- and fifth-order nonlinearities leads to an anomalous dispersion of the total susceptibility.

Study of the laser-induced decomposition of energetic materials at static high-pressure by time-resolved absorption spectroscopy

NASA Astrophysics Data System (ADS)

Hebert, Philippe; Saint-Amans, Charles

2013-06-01

A detailed description of the reaction rates and mechanisms occurring in shock-induced decomposition of condensed explosives is very important to improve the predictive capabilities of shock-to-detonation transition models. However, direct measurements of such experimental data are difficult to perform during detonation experiments. By coupling pulsed laser ignition of an explosive in a diamond anvil cell (DAC) with time-resolved streak camera recording of transmitted light, it is possible to make direct observations of deflagration phenomena at detonation pressure. We have developed an experimental set-up that allows combustion front propagation rates and time-resolved absorption spectroscopy measurements. The decomposition reactions are initiated using a nanosecond YAG laser and their kinetics is followed by time-resolved absorption spectroscopy. The results obtained for two explosives, nitromethane (NM) and HMX are presented in this paper. For NM, a change in reactivity is clearly seen around 25 GPa. Below this pressure, the reaction products are essentially carbon residues whereas at higher pressure, a transient absorption feature is first observed and is followed by the formation of a white amorphous product. For HMX, the evolution of the absorption as a function of time indicates a multi-step reaction mechanism which is found to depend on both the initial pressure and the laser fluence.

Fishing for Features

ScienceCinema

Heredia-Langner, Alejandro; Cort, John; Bailey, Vanessa

2018-01-16

The Fishing for Features Signature Discovery project developed a framework for discovering signature features in challenging environments involving large and complex data sets or where phenomena may be poorly characterized or understood. Researchers at PNNL have applied the framework to the optimization of biofuels blending and to discover signatures of climate change on microbial soil communities.

Fishing for Features

SciTech Connect

Heredia-Langner, Alejandro; Cort, John; Bailey, Vanessa

2016-07-21

The Fishing for Features Signature Discovery project developed a framework for discovering signature features in challenging environments involving large and complex data sets or where phenomena may be poorly characterized or understood. Researchers at PNNL have applied the framework to the optimization of biofuels blending and to discover signatures of climate change on microbial soil communities.

Food Iron Absorption Measured by an Extrinsic Tag

PubMed Central

Cook, J. D.; Layrisse, M.; Martinez-Torres, C.; Walker, R.; Monsen, E.; Finch, C. A.

1972-01-01

The paper describes the use of an extrinsic tag of inorganic radioiron to determine the total absorption of nonheme iron from a complete meal. The method was developed by measuring the iron absorbed from vegetable foods containing biosynthetically incorporated 55Fe (intrinsic tag) and from 59Fe added as a small dose of inorganic iron to the same meal (extrinsic tag). In studies with maize, black bean, and wheat, a consistent extrinsic: intrinsic radioiron absorption ratio averaging 1.10 was observed. Similar results were obtained with either ferrous or ferric iron as the extrinsic tag, and with doses of the latter ranging from 0.001 to 0.5 mg iron added to a test meal containing 2-4 mg of food iron. Adding the radioiron at different stages in preparation of the test meal also had little effect. Separate administration of the extrinsic tag was less satisfactory when small portions of a single food were employed, but with a complete meal, the separate dose was preferable. The extrinsic tag provided a valid measure of absorption despite marked differences in the iron status of the subject, and with wide changes in absorption imposed by adding desferrioxamine or ascorbic acid to the test meal. These findings indicate that there is a common pool of nonheme iron, the absorption of which is influenced by various blocking or enhancing substances present in the meal. PMID:5062612

Absorption degree analysis on biogas separation with ionic liquid systems.

PubMed

Zhang, Xin; Zhang, Suojiang; Bao, Di; Huang, Ying; Zhang, Xiangping

2015-01-01

For biogas upgrading, present work mainly focuses on either thermodynamics or mass transfer properties. A systematical study on these two aspects is important for developing a new biogas separation process. In this work, a new criterion "absorption degree", which combines both thermodynamics and mass transfer properties, was proposed for the first time to comprehensively evaluate the absorption performance. Henry's law constants of CO2 and CH4 in ionic liquids-polyethylene glycol dimethyl ethers mixtures were investigated. The liquid-side mass transfer coefficients (kL) were determined. The results indicate that IL-NHD mixtures exhibit not only a high CO2/CH4 selectivity, but also a fast kL for CO2 absorption. The [bmim][NO3]+NHD mixtures present a high absorption degree value for CO2 but a low value for CH4. For presenting a highest relative absorption degree value, the 50wt% [bmim][NO3]+50wt% NHD mixture is recommended for biogas upgrading. Copyright © 2014 Elsevier Ltd. All rights reserved.

Nonlinear Saturable and Polarization-induced Absorption of Rhenium Disulfide

PubMed Central

Cui, Yudong; Lu, Feifei; Liu, Xueming

2017-01-01

Monolayer of transition metal dichalcogenides (TMDs), with lamellar structure as that of graphene, has attracted significant attentions in optoelectronics and photonics. Here, we focus on the optical absorption response of a new member TMDs, rhenium disulphide (ReS2) whose monolayer and bulk forms have the nearly identical band structures. The nonlinear saturable and polarization-induced absorption of ReS2 are investigated at near-infrared communication band beyond its bandgap. It is found that the ReS2-covered D-shaped fiber (RDF) displays the remarkable polarization-induced absorption, which indicates the different responses for transverse electric (TE) and transverse magnetic (TM) polarizations relative to ReS2 plane. Nonlinear saturable absorption of RDF exhibits the similar saturable fluence of several tens of μJ/cm2 and modulation depth of about 1% for ultrafast pulses with two orthogonal polarizations. RDF is utilized as a saturable absorber to achieve self-started mode-locking operation in an Er-doped fiber laser. The results broaden the operation wavelength of ReS2 from visible light to around 1550 nm, and numerous applications may benefit from the anisotropic and nonlinear absorption characteristics of ReS2, such as in-line optical polarizers, high-power pulsed lasers, and optical communication system. PMID:28053313

Facilities Performance Indicators Report, 2008-09

ERIC Educational Resources Information Center

Hills, Christina, Ed.

2010-01-01

This paper features another expanded Web-based Facilities Performance Indicators Report (FPI). The purpose of APPA's Facilities Performance Indicators is to provide a representative set of statistics about facilities in educational institutions. The 2008-09 iteration of the Web-based Facilities Performance Indicators Survey was posted and…

A tomographic technique for the simultaneous imaging of temperature, chemical species, and pressure in reactive flows using absorption spectroscopy with frequency-agile lasers

SciTech Connect

Cai, Weiwei; Kaminski, Clemens F., E-mail: cfk23@cam.ac.uk

2014-01-20

This paper proposes a technique that can simultaneously retrieve distributions of temperature, concentration of chemical species, and pressure based on broad bandwidth, frequency-agile tomographic absorption spectroscopy. The technique holds particular promise for the study of dynamic combusting flows. A proof-of-concept numerical demonstration is presented, using representative phantoms to model conditions typically prevailing in near-atmospheric or high pressure flames. The simulations reveal both the feasibility of the proposed technique and its robustness. Our calculations indicate precisions of ∼70 K at flame temperatures and ∼0.05 bars at high pressure from reconstructions featuring as much as 5% Gaussian noise in the projections.

Decision trees to characterise the roles of permeability and solubility on the prediction of oral absorption.

PubMed

Newby, Danielle; Freitas, Alex A; Ghafourian, Taravat

2015-01-27

Oral absorption of compounds depends on many physiological, physiochemical and formulation factors. Two important properties that govern oral absorption are in vitro permeability and solubility, which are commonly used as indicators of human intestinal absorption. Despite this, the nature and exact characteristics of the relationship between these parameters are not well understood. In this study a large dataset of human intestinal absorption was collated along with in vitro permeability, aqueous solubility, melting point, and maximum dose for the same compounds. The dataset allowed a permeability threshold to be established objectively to predict high or low intestinal absorption. Using this permeability threshold, classification decision trees incorporating a solubility-related parameter such as experimental or predicted solubility, or the melting point based absorption potential (MPbAP), along with structural molecular descriptors were developed and validated to predict oral absorption class. The decision trees were able to determine the individual roles of permeability and solubility in oral absorption process. Poorly permeable compounds with high solubility show low intestinal absorption, whereas poorly water soluble compounds with high or low permeability may have high intestinal absorption provided that they have certain molecular characteristics such as a small polar surface or specific topology. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Molecular dynamics simulations of collision-induced absorption: Implementation in LAMMPS

NASA Astrophysics Data System (ADS)

Fakhardji, W.; Gustafsson, M.

2017-02-01

We pursue simulations of collision-induced absorption in a mixture of argon and xenon gas at room temperature by means of classical molecular dynamics. The established theoretical approach (Hartmann et al. 2011 J. Chem. Phys. 134 094316) is implemented with the molecular dynamics package LAMMPS. The bound state features in the absorption spectrum are well reproduced with the molecular dynamics simulation in comparison with a laboratory measurement. The magnitude of the computed absorption, however, is underestimated in a large part of the spectrum. We suggest some aspects of the simulation that could be improved.

Defeating feature fatigue.

PubMed

Rust, Roland T; Thompson, Debora Viana; Hamilton, Rebecca W

2006-02-01

Consider a coffeemaker that offers 12 drink options, a car with more than 700 features on the dashboard, and a mouse pad that's also a clock, calculator, and FM radio. All are examples of "feature bloat", or "featuritis", the result of an almost irresistible temptation to load products with lots of bells and whistles. The problem is that the more features a product boasts, the harder it is to use. Manufacturers that increase a product's capability--the number of useful functions it can perform--at the expense of its usability are exposing their customers to feature fatigue. The authors have conducted three studies to gain a better understanding of how consumers weigh a product's capability relative to its usability. They found that even though consumers know that products with more features are harder to use, they initially choose high-feature models. They also pile on more features when given the chance to customize a product for their needs. Once consumers have actually worked with a product, however, usability starts to matter more to them than capability. For managers in consumer products companies, these findings present a dilemma: Should they maximize initial sales by designing high-feature models, which consumers consistently choose, or should they limit the number of features in order to enhance the lifetime value of their customers? The authors' analytical model guides companies toward a happy middle ground: maximizing the net present value of the typical customer's profit stream. The authors also advise companies to build simpler products, help consumers learn which products suit their needs, develop products that do one thing very well, and design market research in which consumers use actual products or prototypes.

Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes

PubMed Central

2015-01-01

We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process. PMID:26120588

Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes.

PubMed

Friese, Daniel H; Bast, Radovan; Ruud, Kenneth

2015-05-20

We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process.

Combined Mössbauer spectroscopic, multi-edge X-ray absorption spectroscopic, and density functional theoretical study of the radical SAM enzyme spore photoproduct lyase.

PubMed

Silver, Sunshine C; Gardenghi, David J; Naik, Sunil G; Shepard, Eric M; Huynh, Boi Hanh; Szilagyi, Robert K; Broderick, Joan B

2014-03-01

Spore photoproduct lyase (SPL), a member of the radical S-adenosyl-L-methionine (SAM) superfamily, catalyzes the direct reversal of the spore photoproduct, a thymine dimer specific to bacterial spores, to two thymines. SPL requires SAM and a redox-active [4Fe-4S] cluster for catalysis. Mössbauer analysis of anaerobically purified SPL indicates the presence of a mixture of cluster states with the majority (40 %) as [2Fe-2S](2+) clusters and a smaller amount (15 %) as [4Fe-4S](2+) clusters. On reduction, the cluster content changes to primarily (60 %) [4Fe-4S](+). The speciation information from Mössbauer data allowed us to deconvolute iron and sulfur K-edge X-ray absorption spectra to uncover electronic (X-ray absorption near-edge structure, XANES) and geometric (extended X-ray absorption fine structure, EXAFS) structural features of the Fe-S clusters, and their interactions with SAM. The iron K-edge EXAFS data provide evidence for elongation of a [2Fe-2S] rhomb of the [4Fe-4S] cluster on binding SAM on the basis of an Fe···Fe scatterer at 3.0 Å. The XANES spectra of reduced SPL in the absence and presence of SAM overlay one another, indicating that SAM is not undergoing reductive cleavage. The X-ray absorption spectroscopy data for SPL samples and data for model complexes from the literature allowed the deconvolution of contributions from [2Fe-2S] and [4Fe-4S] clusters to the sulfur K-edge XANES spectra. The analysis of pre-edge features revealed electronic changes in the Fe-S clusters as a function of the presence of SAM. The spectroscopic findings were further corroborated by density functional theory calculations that provided insights into structural and electronic perturbations that can be correlated by considering the role of SAM as a catalyst or substrate.

The influence of local electric fields on photoinduced absorption in dye-sensitized solar cells.

PubMed

Cappel, Ute B; Feldt, Sandra M; Schöneboom, Jan; Hagfeldt, Anders; Boschloo, Gerrit

2010-07-07

The dye-sensitized solar cell (DSC) challenges conventional photovoltaics with its potential for low-cost production and its flexibility in terms of color and design. Transient absorption spectroscopy is widely used to unravel the working mechanism of DSCs. A surprising, unexplained feature observed in these studies is an apparent bleach of the ground-state absorption of the dye, under conditions where the dye is in the ground state. Here, we demonstrate that this feature can be attributed to a change of the local electric field affecting the absorption spectrum of the dye, an effect related to the Stark effect first reported in 1913. We present a method for measuring the effect of an externally applied electric field on the absorption of dye monolayers adsorbed on flat TiO(2) substrates. The measured signal has the shape of the first derivative of the absorption spectra of the dyes and reverses sign along with the reversion of the direction of the change in dipole moment upon excitation relative to the TiO(2) surface. A very similar signal is observed in photoinduced absorption spectra of dye-sensitized TiO(2) electrodes under solar cell conditions, demonstrating that the electric field across the dye molecules changes upon illumination. This result has important implications for the analysis of transient absorption spectra of DSCs and other molecular optoelectronic devices and challenges the interpretation of many previously published results.

Hydrological and Biogeochemical Controls on Absorption and Fluorescence of Dissolved Organic Matter in the Northern South China Sea

NASA Astrophysics Data System (ADS)

Wang, Chao; Guo, Weidong; Li, Yan; Stubbins, Aron; Li, Yizhen; Song, Guodong; Wang, Lei; Cheng, Yuanyue

2017-12-01

The Kuroshio intrusion from the West Philippine Sea (WPS) and mesoscale eddies are important hydrological features in the northern South China Sea (SCS). In this study, absorption and fluorescence of dissolved organic matter (CDOM and FDOM) were determined to assess the impact of these hydrological features on DOM dynamics in the SCS. DOM in the upper 100 m of the northern SCS had higher absorption, fluorescence, and degree of humification than in the Kuroshio Current of the WPS. The results of an isopycnal mixing model showed that CDOM and humic-like FDOM inventories in the upper 100 m of the SCS were modulated by the Kuroshio intrusion. However, protein-like FDOM was influenced by in situ processes. This basic trend was modified by mesoscale eddies, three of which were encountered during the fieldwork (one warm eddy and two cold eddies). DOM optical properties inside the warm eddy resembled those of DOM in the WPS, indicating that warm eddies could derive from the Kuroshio Current through Luzon Strait. DOM at the center of cold eddies was enriched in humic-like fluorescence and had lower spectral slopes than in eddy-free waters, suggesting inputs of humic-rich DOM from upwelling and enhanced productivity inside the eddy. Excess CDOM and FDOM in northern SCS intermediate water led to export to the Pacific Ocean interior, potentially delivering refractory carbon to the deep ocean. This study demonstrated that DOM optical properties are promising tools to study active marginal sea-open ocean interactions.

JCE Feature Columns

NASA Astrophysics Data System (ADS)

Holmes, Jon L.

1999-05-01

The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online (jceonline@chem.wisc.edu) know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad

Crystalline sulfur dioxide: Crystal field splittings, absolute band intensities and complex refractive indices derived from infrared spectra

NASA Technical Reports Server (NTRS)

Khanna, R. K.; Zhao, Guizhi

1986-01-01

The infrared absorption spectra of thin crystalline films of sulfur dioxide at 90 K are reported in the 2700 to 450/cm region. The observed multiplicity of the spectral features in the regions of fundamentals is attributed to factor group splittings of the modes in a biaxial crystal lattice and the naturally present minor S-34, S-36, and O-18 isotopic species. Complex refractive indices determined by an iterative Kramers-Kronig analysis of the extinction data, and absolute band strengths derived from them, are also reported in this region.

Iron Absorption in Drosophila melanogaster

PubMed Central

Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

2013-01-01

The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration. PMID:23686013

Iodine Absorption Cells Purity Testing

PubMed Central

Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

2017-01-01

This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions’ spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches). PMID:28067834

QED-driven laser absorption

NASA Astrophysics Data System (ADS)

Levy, Matthew; Blackburn, T.; Ratan, N.; Sadler, J.; Ridgers, C.; Kasim, M.; Ceurvorst, L.; Holloway, J.; Baring, M.; Bell, A.; Glenzer, S.; Gregori, G.; Ilderton, A.; Marklund, M.; Tabak, M.; Wilks, S.; Norreys, P.

2016-10-01

Absorption covers the physical processes which convert intense photon flux into energetic particles when a high-power laser (I >1018 W cm-2 where I is intensity at 1 μm wavelength) illuminates optically-thick matter. It underpins important applications of petawatt laser systems today, e.g., in isochoric heating of materials. Next-generation lasers such as ELI are anticipated to produce quantum electrodynamical (QED) bursts of γ-rays and anti-matter via the multiphoton Breit-Wheeler process which could enable scaled laboratory probes, e.g., of black hole winds. Here, applying strong-field QED to advances in plasma kinematic theory, we present a model elucidating absorption limited only by an avalanche of self-created electron-positron pairs at ultra-high-field. The model, confirmed by multidimensional QED-PIC simulations, works over six orders of magnitude in optical intensity and reveals this cascade is initiated at 1.8 x 1025 W cm-2 using a realistic linearly-polarized laser pulse. Here the laser couples its energy into highly-collimated electrons, ions, γ-rays, and positrons at 12%, 6%, 58% and 13% efficiency, respectively. We remark on attributes of the QED plasma state and possible applications.

Sulphate absorption across biological membranes.

PubMed

Mitchell, Stephen C; Waring, Rosemary H

2016-01-01

1. Sulphonation is unusual amongst the common Phase II (condensation; synthetic) reactions experienced by xenobiotics, in that the availability of the conjugating agent, sulphate, may become a rate-limiting factor. This sulphate is derived within the body via the oxygenation of sulphur moieties liberated from numerous ingested compounds including the sulphur-containing amino acids. Preformed inorganic sulphate also makes a considerable contribution to this pool. 2. There has been a divergence of opinion as to whether or not inorganic sulphate may be readily absorbed from the gastrointestinal tract and this controversy still continues in some quarters. Even more so, is the vexing question of potential absorption of inorganic sulphate via the lungs and through the skin. 3. This review examines the relevant diverse literature and concludes that sulphate ions may move across biological membranes by means of specific transporters and, although the gastrointestinal tract is by far the major portal of entry, some absorption across the lungs and the skin may take place under appropriate circumstances.

Health Care Indicators for the United States

PubMed Central

Donham, Carolyn S.; Maple, Brenda T.; Levit, Katharine R.

1992-01-01

Contained in this regular feature of the journal is a section on each of the following four topics community hospital statistics; employment, hours, and earnings in the private health sector; health care prices; and national economic indicators. PMID:10122005

Two-photon absorption in layered transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Dong, Ningning; Zhang, Saifeng; Li, Yuanxin; Wang, Jun

2018-02-01

Two-dimensional (2D) layered transition metal dichalcogenides (TMDCs) exhibit unique nonlinear optical (NLO) features and have becoming intriguing and promising candidate materials for photonic and optoelectronic devices with high performance and unique functions. Owing to layered geometry and the thickness-dependent bandgap, we studied the ultrafast NLO properties of a range of TMDCs. TMDCs with high-quality layered nanosheets were prepared through chemical vapor deposition (CVD) technique and vapor-phase growth method. Saturable absorption, two photon absorption (TPA) and two photon pumped frequency up-converted luminescence were observed from these 2D nanostructures. The exciting results open up the door to 2D photonic devices, such as passive mode-lockers, Q-switchers, optical limiters, light emitters, etc.

Interfacial charge transfer absorption: Application to metal molecule assemblies

NASA Astrophysics Data System (ADS)

Creutz, Carol; Brunschwig, Bruce S.; Sutin, Norman

2006-05-01

Optically induced charge transfer between adsorbed molecules and a metal electrode was predicted by Hush to lead to new electronic absorption features, but has been only rarely observed experimentally. Interfacial charge transfer absorption (IFCTA) provides information concerning the barriers to charge transfer between molecules and the metal/semiconductor and the magnitude of the electronic coupling and could thus provide a powerful tool for understanding interfacial charge-transfer kinetics. Here, we utilize a previously published model [C. Creutz, B.S. Brunschwig, N. Sutin, J. Phys. Chem. B 109 (2005) 10251] to predict IFCTA spectra of metal-molecule assemblies and compare the literature observations to these predictions. We conclude that, in general, the electronic coupling between molecular adsorbates and the metal levels is so small that IFCTA is not detectable. However, few experiments designed to detect IFCTA have been done. We suggest approaches to optimizing the conditions for observing the process.

Features of resilience

USGS Publications Warehouse

Connelly, Elizabeth B.; Allen, Craig R.; Hatfield, Kirk; Palma-Oliveira, José M.; Woods, David D.; Linkov, Igor

2017-01-01

The National Academy of Sciences (NAS) definition of resilience is used here to organize common concepts and synthesize a set of key features of resilience that can be used across diverse application domains. The features in common include critical functions (services), thresholds, cross-scale (both space and time) interactions, and memory and adaptive management. We propose a framework for linking these features to the planning, absorbing, recovering, and adapting phases identified in the NAS definition. The proposed delineation of resilience can be important in understanding and communicating resilience concepts.

Features of resilience

DOE PAGES

Connelly, Elizabeth B.; Allen, Craig R.; Hatfield, Kirk; ...

2017-02-20

The National Academy of Sciences (NAS) definition of resilience is used here to organize common concepts and synthesize a set of key features of resilience that can be used across diverse application domains. The features in common include critical functions (services), thresholds, cross-scale (both space and time) interactions, and memory and adaptive management. We propose a framework for linking these features to the planning, absorbing, recovering, and adapting phases identified in the NAS definition. As a result, the proposed delineation of resilience can be important in understanding and communicating resilience concepts.

[Spectral absorption properties of the water constituents in the estuary of Zhujiang River].

PubMed

Wang, Shan-shan; Wang, Yong-bo; Fu, Qing-hua; Yin, Bin; Li, Yun-mei

2014-12-01

Spectral absorption properties of the water constituents is the main factor affecting the light field under the surface of the water and the spectrum above the surface of the water. Thus, the study is useful for understanding of the water spectral property and the remote reversing of water quality parameters. Absorption properties of total suspended particles, non-algal particles, phytoplankton and CDOM were analyzed using the 30 samples collected in July 2013 in the estuary of Zhujiang River. The results indicated that: (1) the non-algal particles absorption dominated the absorption of the total suspended particles; (2) the absorption coefficient of the non-algal particles, which mainly came from the terrigenous deposits, decreased exponentially from short to long wavelength. In addition, the average value and spatial variation of the slope S(d) were higher than those in inland case- II waters; (3) the absorption coefficient of phytoplankton in 440 nm showed a better polynomial relationship with chlorophyll a concentration, while the absorption coefficient of phytoplankton in 675 nm linearly related with the chlorophyll a concentration. Moreover, the influence of accessory pigments on phytoplankton absorption coefficient mainly existed in the range of short wavelength, and Chlorophyll a was the main influencing factor for phytoplankton absorption in long wavelength. The specific absorption coefficient of phytoplankton decreased the power exponentially with the increase of the chlorophyll a concentration; (4) CDOM mainly came from the terrigenous sources and its spectral curve had an absorption shoulder between 250-290 nm. Thus, a piecewise S(g) fitting function could effectively express CDOM absorption properties, i.e., M value and S(g) value in period A (240-260 nm) showed a strong positive correlation. The M value was low, and the humic acid had a high proportion in CDOM; (5) the non-algal particles absorption dominated the total absorption in the estuary of

Community Perceptions of Specific Skin Features of Possible Melanoma

ERIC Educational Resources Information Center

Baade, Peter D.; Balanda, Kevin P.; Stanton, Warren R.; Lowe, John B.; Del Mar, Chris B.

2004-01-01

Background: Melanoma can be curable if detected early. One component of detecting melanoma is an awareness of the important features of the disease. It is currently not clear which features the community view as indicative of melanoma. Objective: To investigate which features of the skin members of an urban community believe may indicate skin…

AQUATOX Features and Tools

EPA Pesticide Factsheets

Numerous features have been included to facilitate the modeling process, from model setup and data input, presentation and analysis of results, to easy export of results to spreadsheet programs for additional analysis.

Abdominal cocoon: sonographic features.

PubMed

Vijayaraghavan, S Boopathy; Palanivelu, Chinnusamy; Sendhilkumar, Karuppusamy; Parthasarathi, Ramakrishnan

2003-07-01

An abdominal cocoon is a rare condition in which the small bowel is encased in a membrane. The diagnosis is usually established at surgery. Here we describe the sonographic features of this condition.

Feature Extraction Assessment Study.

DTIC Science & Technology

1984-11-01

base in the form of orthophotos , control manuscripts, . or maps or charts; aids to feature identification such as im- agery (rectified and unrectified...manually delineated (i.e. , drawn by * hand) on a feature manuscript which may be a mylar overlay on an orthophoto or other control base. Once delineated...partition of tiled constant gray level regions, with addi- tive noise in each, it is not clear that any segmentation tech- nique would identify each

Dynamics of feature categorization.

PubMed

Martí, Daniel; Rinzel, John

2013-01-01

In visual and auditory scenes, we are able to identify shared features among sensory objects and group them according to their similarity. This grouping is preattentive and fast and is thought of as an elementary form of categorization by which objects sharing similar features are clustered in some abstract perceptual space. It is unclear what neuronal mechanisms underlie this fast categorization. Here we propose a neuromechanistic model of fast feature categorization based on the framework of continuous attractor networks. The mechanism for category formation does not rely on learning and is based on biologically plausible assumptions, for example, the existence of populations of neurons tuned to feature values, feature-specific interactions, and subthreshold-evoked responses upon the presentation of single objects. When the network is presented with a sequence of stimuli characterized by some feature, the network sums the evoked responses and provides a running estimate of the distribution of features in the input stream. If the distribution of features is structured into different components or peaks (i.e., is multimodal), recurrent excitation amplifies the response of activated neurons, and categories are singled out as emerging localized patterns of elevated neuronal activity (bumps), centered at the centroid of each cluster. The emergence of bump states through sequential, subthreshold activation and the dependence on input statistics is a novel application of attractor networks. We show that the extraction and representation of multiple categories are facilitated by the rich attractor structure of the network, which can sustain multiple stable activity patterns for a robust range of connectivity parameters compatible with cortical physiology.

Particle agglomerated 3-d nanostructures for photon absorption

NASA Astrophysics Data System (ADS)

Sivayoganathan, Mugunthan

when compared with the previous nanostructures used in photovoltaic conversion. Several features of nanostructures contribute to the enhancement of this light absorption. The special feature of the structure is that ease to fabricate and modify the properties by varying the laser parameters could make it competitive among other nanostructures available for solar cells.

Quantum-enhanced absorption refrigerators

PubMed Central

Correa, Luis A.; Palao, José P.; Alonso, Daniel; Adesso, Gerardo

2014-01-01

Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators. PMID:24492860

Multistage quantum absorption heat pumps.

PubMed

Correa, Luis A

2014-04-01

It is well known that heat pumps, while being all limited by the same basic thermodynamic laws, may find realization on systems as "small" and "quantum" as a three-level maser. In order to quantitatively assess how the performance of these devices scales with their size, we design generalized N-dimensional ideal heat pumps by merging N-2 elementary three-level stages. We set them to operate in the absorption chiller mode between given hot and cold baths and study their maximum achievable cooling power and the corresponding efficiency as a function of N. While the efficiency at maximum power is roughly size-independent, the power itself slightly increases with the dimension, quickly saturating to a constant. Thus, interestingly, scaling up autonomous quantum heat pumps does not render a significant enhancement beyond the optimal double-stage configuration.

Sound absorption with green materials

NASA Astrophysics Data System (ADS)

Trematerra, Amelia; Lombardi, Ilaria

2017-07-01

Green materials are a valid alternative to traditional materials that are by-products of processing oil. At the end of their useful life, green materials can be disposed of without polluting the environment. They are now being used in the construction and automotive industries. While, studies are currently being carried out in the aviation sector on the use of green materials for non-structural components of airplanes. Green materials can be used to improve the acoustic comfort inside buildings as well as mitigate reverberation, echoes effects and reduce the transmission of noise between rooms. In this paper, the acoustic measurements of the properties of green materials are reported. The absorption coefficient of samples of the materials were measured in the frequency range from 200 Hz to 2,000 Hz with an impedance tube, with the flow resistance being measured.

Acoustic Absorption in Porous Materials

NASA Technical Reports Server (NTRS)

Kuczmarski, Maria A.; Johnston, James C.

2011-01-01

An understanding of both the areas of materials science and acoustics is necessary to successfully develop materials for acoustic absorption applications. This paper presents the basic knowledge and approaches for determining the acoustic performance of porous materials in a manner that will help materials researchers new to this area gain the understanding and skills necessary to make meaningful contributions to this field of study. Beginning with the basics and making as few assumptions as possible, this paper reviews relevant topics in the acoustic performance of porous materials, which are often used to make acoustic bulk absorbers, moving from the physics of sound wave interactions with porous materials to measurement techniques for flow resistivity, characteristic impedance, and wavenumber.

HI Absorption in Merger Remnants

NASA Technical Reports Server (NTRS)

Teng, Stacy H.; Veileux, Sylvain; Baker, Andrew J.

2012-01-01

It has been proposed that ultraluminous infrared galaxies (ULIRGs) pass through a luminous starburst phase, followed by a dust-enshrouded AGN phase, and finally evolve into optically bright "naked" quasars once they shed their gas/dust reservoirs through powerful wind events. We present the results of our recent 21- cm HI survey of 21 merger remnants with the Green Bank Telescope. These remnants were selected from the QUEST (Quasar/ULIRG Evolution Study) sample of ULIRGs and PG quasars; our targets are all bolometrically dominated by AGN and sample all phases of the proposed ULIRG -> IR-excess quasar -> optical quasar sequence. We explore whether there is an evolutionary connection between ULIRGs and quasars by looking for the occurrence of HI absorption tracing neutral gas outflows; our results will allow us to identify where along the sequence the majority of a merger's gas reservoir is expelled.

Backscatter absorption gas imaging system

DOEpatents

McRae, Jr., Thomas G.

1985-01-01

A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

Backscatter absorption gas imaging system

DOEpatents

McRae, T.G. Jr.

A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

Spectral features of biogenic calcium carbonates and implications for astrobiology

NASA Astrophysics Data System (ADS)

Berg, B. L.; Ronholm, J.; Applin, D. M.; Mann, P.; Izawa, M.; Cloutis, E. A.; Whyte, L. G.

2014-09-01

The ability to discriminate biogenic from abiogenic calcium carbonate (CaCO3) would be useful in the search for extant or extinct life, since CaCO3 can be produced by both biotic and abiotic processes on Earth. Bioprecipitated CaCO3 material was produced during the growth of heterotrophic microbial isolates on medium enriched with calcium acetate or calcium citrate. These biologically produced CaCO3, along with natural and synthetic non-biologically produced CaCO3 samples, were analysed by reflectance spectroscopy (0.35-2.5 μm), Raman spectroscopy (532 and 785 nm), and laser-induced fluorescence spectroscopy (365 and 405 nm excitation). Optimal instruments for the discrimination of biogenic from abiogenic CaCO3 were determined to be reflectance spectroscopy, and laser-induced fluorescence spectroscopy. Multiple absorption features in the visible light region occurred in reflectance spectra for most biogenic CaCO3 samples, which are likely due to organic pigments. Multiple fluorescence peaks occurred in emission spectra (405 nm excitation) of biogenic CaCO3 samples, which also are best attributed to the presence of organic compounds; however, further analyses must be performed in order to better determine the cause of these features to establish criteria for confirming the origin of a given CaCO3 sample. Raman spectroscopy was not useful for discrimination since any potential Raman peaks in spectra of biogenic carbonates collected by both the 532 and 785 nm lasers were overwhelmed by fluorescence. However, this also suggests that biogenic carbonates may be identified by the presence of this organic-associated fluorescence. No reliable spectroscopic differences in terms of parameters such as positions or widths of carbonate-associated absorption bands were found between the biogenic and abiogenic carbonate samples. These results indicate that the presence or absence of organic matter intimately associated with carbonate minerals is the only potentially useful

Textural features for image classification

NASA Technical Reports Server (NTRS)

Haralick, R. M.; Dinstein, I.; Shanmugam, K.

1973-01-01

Description of some easily computable textural features based on gray-tone spatial dependances, and illustration of their application in category-identification tasks of three different kinds of image data - namely, photomicrographs of five kinds of sandstones, 1:20,000 panchromatic aerial photographs of eight land-use categories, and ERTS multispectral imagery containing several land-use categories. Two kinds of decision rules are used - one for which the decision regions are convex polyhedra (a piecewise-linear decision rule), and one for which the decision regions are rectangular parallelpipeds (a min-max decision rule). In each experiment the data set was divided into two parts, a training set and a test set. Test set identification accuracy is 89% for the photomicrographs, 82% for the aerial photographic imagery, and 83% for the satellite imagery. These results indicate that the easily computable textural features probably have a general applicability for a wide variety of image-classification applications.

Detection of absorption lines in the spectra of X-ray bursts from X1608-52

NASA Astrophysics Data System (ADS)

Nakamura, Norio; Inoue, Hajime; Tanaka, Yasuo

X-ray bursts from X 1608-52 were observed with the gas scintillation proportional counters on the Tenma satellite. Absorption features were detected in the spectra of three bursts among 17 bursts observed. These absorption features are consistent with a common absorption line at 4.1 keV. The energy and the properties of the absorption lines of the X 1608-52 bursts are very similar to those observed from the X 1636-53 bursts by Waki et al. (1984). Near equality of the absorption-line energies for X 1636-53 and X 1608-52 would imply that mass and radius of the neutron stars in these two systems are very similar to each other.

[Absorption Characteristics of Particulates and CDOM in Waters of Chagan Lake and Xinlicheng Reservoir in Autumn].

PubMed

Li, Si-jia; Song, Kai-shan; Zhao, Ying; Mu, Guang-yi; Shao, Tian-tian; Ma, Jian-hang

2016-01-15

Field surveys and laboratory analysis were carried out in Chagan Lake and Xinlicheng Reservoir under different salinity conditions in September 2012. In the laboratory, the absorption coefficients of particulates and chromophoric dissolved organic matter (CDOM) were measured, aiming to compare the absorption features, source of optical active substances and relative contribution of optical active constituents over the range of PAR (400-700 nm) in Chagan Lake and Xinlicheng Reservoir. The results showed that the Chagan Lake and Xinlicheng Reservoir were water bodies with medium eutrophication in autumn by TAL nutrient index and the absorption spectra of particulates matters were similar to those of phytoplankton. For the Chagan Lake with high salinity( EC = 988. 87 micro S x cm(-1)), the total particulate absorption was dominated by the nonalgal particles, and the contribution rate was in the order of nonalgal particles > phytoplankton > CDOM. For the Xinlicheng Reservoir with low salinity (EC = 311.67 microS x -cm(-1)), the total particulate absorption was dominated by the phytoplankton, and the contribution rate was ranked as phytoplankton > nonalgal particles > CDOM. Positive correlation was observed between a(p) (440), a(p) (675), a(d) (440) and total suspended matter (TSM), inorganic suspended matter (ISM), organic suspended matter (OSM) and Chl-a respectively in Chagan Lake, with correlation coefficients all above 0.55. Positive correlation was observed between a(p)(440), a(p) (675) and Chl-a (0.77 and 0.85, P < 0.05) , so did a(d) (440) and ISM (0.74, P < 0.01), while negative correlation was observed between a(p) (440) and OSM in the Xinlicheng Reservoir. In terms of Chagan Lake, negative correlation was merely observed between a(g) (440) and OSM (-0.54, P < 0.05) , but not in the Xinlicheng Reservoir. Both Sg, which was calculated by the fitting absorption curve from 250 to 400 nm, and relative molecular weight M showed that Sg[ (0.021 +/- 0.001) m(-1)] in

Narrow absorption lines complex I: one form of broad absorption line

NASA Astrophysics Data System (ADS)

Lu, Wei-Jian; Lin, Ying-Ru

2018-03-01

We discover that some of the broad absorption lines (BALs) are actually a complex of narrow absorption lines (NALs). As a pilot study of this type of BAL, we show this discovery through a typical example in this paper. Utilizing the two-epoch observations of J002710.06-094435.3 (hereafter J0027-0944) from the Sloan Digital Sky Survey (SDSS), we find that each of the C IV and Si IV BAL troughs contains at least four NAL doublets. By resolving the Si IV BAL into multiple NALs, we present the following main results and conclusions. First, all these NALs show coordinated variations between the two-epoch SDSS observations, suggesting that they all originate in the quasar outflow, and that their variations are due to global changes in the ionization condition of the absorbing gas. Secondly, a BAL consisting of a number of NAL components indicates that this type of BAL is basically the same as the intrinsic NAL, which tends to support the inclination model rather than the evolution model. Thirdly, although both the C IV and Si IV BALs originate from the same clumpy substructures of the outflow, they show different profile shapes: multiple absorption troughs for the Si IV BAL in a wider velocity range, while P-Cygni for the C IV BAL in a narrower velocity range. This can be interpreted by the substantial differences in fine structure and oscillator strength between the Si IVλλ1393, 1402 and C IVλλ1548, 1551 doublets. Based on the above conclusions, we consider that the decomposition of a BAL into NALs can serve as a way to resolve the clumpy structure for outflows, and it can be used to learn more about characteristics of the clumpy structure and to test the outflow model, when utilizing high-resolution spectra and photoionization model.

Vitamin B12 absorption from eggs.

PubMed

Doscherholmen, A; McMahon, J; Ripley, D

1975-09-01

The assimilation of 57Co B12 from in vivo labeled eggs was much inferior to that of a comparable amount of crystalline 57Co B12. Furthermore, the absorption varied with the form in which the eggs were served. Judged by the urinary excretion test and the plasma absorption of radioactivity the average absorption from boiled and fried eggs was more than twice that from scrambled whole eggs, but less than half that absorbed from crystalline 57Co B12.

On pulsating cosmic /radio/ noise absorption

NASA Technical Reports Server (NTRS)

Dangelo, N.

1981-01-01

It has been proposed that some absorption events measured on riometers are actually due to backscatter of cosmic radio noise by E-region plasma waves (D'Angelo, 1976, 1978; D'Angelo and Mehta, 1980). Assuming that DC or nearly DC absorption is a viable process, it is shown that it may also be operative in producing pulsations in cosmic noise absorption on riometers, with periods ranging from a few seconds to several minutes.

Absorption Coefficient of Alkaline Earth Halides.

DTIC Science & Technology

1980-04-01

not observed at low energy level , are developed at high power levels . No matter how low the absorption is. the effect is objectionable at high-energy... levels . As a natural consequence, the magnitude of the absorption coefficient is the key parameter in selecting laser window materials. Over the past...Presence of impurities can complicate the exponential tail. particularly at low absorption levels . The impurities may enter 12 the lattice singly or

Observational Evidence Linking Interstellar UV Absorption to PAH Molecules

SciTech Connect

Blasberger, Avi; Behar, Ehud; Perets, Hagai B.

The 2175 Å UV extinction feature was discovered in the mid-1960s, yet its physical origin remains poorly understood. One suggestion is absorption by polycyclic aromatic hydrocarbon (PAH) molecules, which is supported by theoretical molecular structure computations and by laboratory experiments. PAHs are positively detected by their 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 μ m IR emission bands, which are specified by their modes of vibration. A definitive empirical link between the 2175 Å UV extinction and the IR PAH emission bands, however, is still missing. We present a new sample of hot stars that have both 2175 Å absorptionmore » and IR PAH emission. We find significant shifts of the central wavelength of the UV absorption feature, up to 2350 Å, but predominantly in stars that also have IR PAH emission. These UV shifts depend on stellar temperature in a fashion that is similar to the shifts of the 6.2 and 7.7 μ m IR PAH bands, that is, the features are increasingly more redshifted as the stellar temperature decreases, but only below ∼15 kK. Above 15 kK both UV and IR features retain their nominal values. Moreover, we find a suggestive correlation between the UV and IR shifts. We hypothesize that these similar dependences of both the UV and IR features on stellar temperature hint at a common origin of the two in PAH molecules and may establish the missing link between the UV and IR observations. We further suggest that the shifts depend on molecular size, and that the critical temperature of ∼15 kK above which no shifts are observed is related to the onset of UV-driven hot-star winds and their associated shocks.« less

Near-infrared absorption spectroscopy of interstellar hydrocarbon grains

NASA Astrophysics Data System (ADS)

Pendleton, Y. J.; Sandford, S. A.; Allamandola, L. J.; Tielens, A. G. G. M.; Sellgren, K.

1994-12-01

We present new 3600 - 2700/cm (2.8 - 3.7 micrometer) spectra of objects whose extinction is dominated by dust in the diffuse interstellar medium. The observations presented here augment an ongoing study of the organic component of the diffuse interstellar medium. These spectra contain a broad feature centered near 3300/cm (3.0 micrometers) and/or a feature with a more complex profile near 2950/cm (3.4 micrometers), the latter of which is attributed to saturated aliphatic hydrocarbons in interstellar grains and is the primary interest of this paper. As in our earlier work, the similarity of the absorption bands near 2950/cm (3.4 micrometers) along different lines of sight and the correlation of these features with interstellar extinction reveal that the carrier of this band lies in the dust in the diffuse interstellar medium (DISM). At least 2.5% of the cosmic carbon in the local interstellar medium and 4% toward the Galactic center is tied up in the carrier of the 2950/cm (3.4 micrometer) band. The spectral structure of the diffuse dust hydrocarbon C-H stretch absorption features is reasonably similar to UV photolyzed laboratory ice residues and is quite similar to the carbonaceous component of the Murchison meteorite. The similarity between the DISM and the meteoritic spectrum suggests that some of the interstellar material originally incorporated into the solar nebula may have survived relatively untouched in primitive solar system bodies. Comparisons of the DISM spectrum to hydrogenated amorphous carbon and quenched carbonaceous composite are also presented. The AV/tau ratio for the 2950/cm (3.4 micrometer) feature is lower toward the Galactic center than toward sources in the local solar neighborhood (approximately 150 for the Galactic center sources vs. approximately 250 for the local ISM sources). A similar trend has been observed previously for silicates in the diffuse medium by Roche & Aitken, suggesting that (1) the silicate and carbonaceous materials in

Near-infrared absorption spectroscopy of interstellar hydrocarbon grains

NASA Technical Reports Server (NTRS)

Pendleton, Y. J.; Sandford, S. A.; Allamandola, L. J.; Tielens, A. G. G. M.; Sellgren, K.

1994-01-01

We present new 3600 - 2700/cm (2.8 - 3.7 micrometer) spectra of objects whose extinction is dominated by dust in the diffuse interstellar medium. The observations presented here augment an ongoing study of the organic component of the diffuse interstellar medium. These spectra contain a broad feature centered near 3300/cm (3.0 micrometers) and/or a feature with a more complex profile near 2950/cm (3.4 micrometers), the latter of which is attributed to saturated aliphatic hydrocarbons in interstellar grains and is the primary interest of this paper. As in our earlier work, the similarity of the absorption bands near 2950/cm (3.4 micrometers) along different lines of sight and the correlation of these features with interstellar extinction reveal that the carrier of this band lies in the dust in the diffuse interstellar medium (DISM). At least 2.5% of the cosmic carbon in the local interstellar medium and 4% toward the Galactic center is tied up in the carrier of the 2950/cm (3.4 micrometer) band. The spectral structure of the diffuse dust hydrocarbon C-H stretch absorption features is reasonably similar to UV photolyzed laboratory ice residues and is quite similar to the carbonaceous component of the Murchison meteorite. The similarity between the DISM and the meteoritic spectrum suggests that some of the interstellar material originally incorporated into the solar nebula may have survived relatively untouched in primitive solar system bodies. Comparisons of the DISM spectrum to hydrogenated amorphous carbon and quenched carbonaceous composite are also presented. The A(sub V)/tau ratio for the 2950/cm (3.4 micrometer) feature is lower toward the Galactic center than toward sources in the local solar neighborhood (approximately 150 for the Galactic center sources vs. approximately 250 for the local ISM sources). A similar trend has been observed previously for silicates in the diffuse medium by Roche & Aitken, suggesting that (1) the silicate and carbonaceous

NARROW LINE ABSORPTION IN CACO3.

DTIC Science & Technology

CARBONATES), (*CALCIUM COMPOUNDS, (*ABSORPTION SPECTRA, CALCITE), (*CALCITE, RADIATION EFFECTS), ELECTRON PARAMAGNETIC RESONANCE, SINGLE CRYSTALS , NEUTRONS, X RAYS, GAMMA RAYS, IONS, CRYSTAL DEFECTS, PARAMAGNETIC RESONANCE.

Occupational absorption of tellurium: a report of two cases.

PubMed Central

Blackadder, E S; Manderson, W G

1975-01-01

Industrial uses of tellurium are limited, and reported cases of tellurium absorption of occupational origin are rare. Two such cases are reported here. Both showed typical signs and symptoms of intoxication; in particular, the stench of sour garlic was noted on breath and from excreta. An unusual feature was the bluish-black discoloration of the webs of the fingers and streaks on the face and neck. Full hospital investigation was negative. No permanent damage resulted and each patient made a spontaneous recovery without treatment. Images PMID:123755

Phytoplankton Pigment Communities Can be Modeled Using Unique Relationships With Spectral Absorption Signatures in a Dynamic Coastal Environment

NASA Astrophysics Data System (ADS)

Catlett, D.; Siegel, D. A.

2018-01-01

Understanding the roles of phytoplankton community composition in the functioning of marine ecosystems and ocean biogeochemical cycles is important for many ocean science problems of societal relevance. Remote sensing currently offers the only feasible method for continuously assessing phytoplankton community structure on regional to global scales. However, methods are presently hindered by the limited spectral resolution of most satellite sensors and by uncertainties associated with deriving quantitative indices of phytoplankton community structure from phytoplankton pigment concentrations. Here we analyze a data set of concurrent phytoplankton pigment concentrations and phytoplankton absorption coefficient spectra from the Santa Barbara Channel, California, to develop novel optical oceanographic models for retrieving metrics of phytoplankton community composition. Cluster and Empirical Orthogonal Function analyses of phytoplankton pigment concentrations are used to define up to five phytoplankton pigment communities as a representation of phytoplankton functional types. Unique statistical relationships are found between phytoplankton pigment communities and absorption features isolated using spectral derivative analysis and are the basis of predictive models. Model performance is substantially better for phytoplankton pigment community indices compared with determinations of the contributions of individual pigments or taxa to chlorophyll a. These results highlight the application of data-driven chemotaxonomic approaches for developing and validating bio-optical algorithms and illustrate the potential and limitations for retrieving phytoplankton community composition from hyperspectral satellite ocean color observations.

Ultrafast Transient Absorption Spectroscopy Investigation of Photoinduced Dynamics in Novel Donor-Acceptor Core-Shell Nanostructures for Organic Photovoltaics

NASA Astrophysics Data System (ADS)

Strain, Jacob; Jamhawi, Abdelqader; Abeywickrama, Thulitha M.; Loomis, Wendy; Rathnayake, Hemali; Liu, Jinjun

2016-06-01

Novel donor-acceptor nanostructures were synthesized via covalent synthesis and/or UV cross-linking method. Their photoinduced dynamics were investigated with ultrafast transient absorption (TA) spectroscopy. These new nanostructures are made with the strategy in mind to reduce manufacturing steps in the process of fabricating an organic photovoltaic cell. By imitating the heterojunction interface within a fixed particle domain, several fabrication steps can be bypassed reducing cost and giving more applicability to other film deposition methods. Such applications include aerosol deposition and ink-jet printing. The systems that were studied by TA spectroscopy include PDIB core, PDIB-P3HT core-shell, and PDIB-PANT core-shell which range in size from 60 to 130 nm. Within the experimentally accessible spectra range there resides a region of ground state bleaching, stimulated emission, and excited-state absorption of both neutrals and anions. Control experiments have been carried out to assign these features. At high pump fluences the TA spectra of PDIB core alone also indicate an intramolecular charge separation. The TA spectroscopy results thus far suggest that the core-shells resemble the photoinduced dynamics of a standard film although the particles are dispersed in solution, which indicates the desired outcome of the work.

Enhanced Microwave Absorption Properties of Carbon Black/Silicone Rubber Coating by Frequency-Selective Surface

NASA Astrophysics Data System (ADS)

Yang, Zhaoning; Luo, Fa; Gao, Lu; Qing, Yuchang; Zhou, Wancheng; Zhu, Dongmei

2016-10-01

A square frequency-selective surface (FSS) design has been employed to improve the microwave absorption properties of carbon black/silicone rubber (CBSR) composite coating. The FSS is placed on the surface of the CBSR coating. The effects of FSS design parameters on the microwave absorption properties of the CBSR coating have been investigated, including the size and period of the FSS design, and the thickness and permittivity of the coating. Simulation results indicate that the absorption peak for the CBSR coating alone is related to its thickness and electromagnetic parameters, while the combination of the CBSR coating with a FSS can exhibit a new absorption peak in the reflection curve; the frequency of the new absorption peak is determined by the resonance of the square FSS design and tightly depends on the size of the squares, with larger squares in the FSS design leading to a lower frequency of the new absorption peak. The enhancement of the absorption performance depends on achievement of a new absorption peak using a suitable size and period of the FSS design. In addition, the FSS design has a stable frequency response for both transverse electromagnetic (TE) and transverse magnetic (TM) polarizations as the incident angle varies from 0° to 40°. The optimized results indicate that the bandwidth with reflection loss below -5 dB can encompass the whole frequency range from 8 GHz to 18 GHz for thickness of the CBSR coating of only 1.8 mm. The simulation results are confirmed by experiments.

Thermal indicator for wells

DOEpatents

Gaven, Jr., Joseph V.; Bak, Chan S.

1983-01-01

Minute durable plate-like thermal indicators are employed for precision measuring static and dynamic temperatures of well drilling fluids. The indicators are small enough and sufficiently durable to be circulated in the well with drilling fluids during the drilling operation. The indicators include a heat resistant indicating layer, a coacting meltable solid component and a retainer body which serves to unitize each indicator and which may carry permanent indicator identifying indicia. The indicators are recovered from the drilling fluid at ground level by known techniques.

Three featured plenary sessions

NASA Astrophysics Data System (ADS)

2012-07-01

The conference included three plenary sessions. The plenary on Governance, Security, Economy, and the Ecosystem of the Changing Arctic featured Vera Alexander, president, Arctic Research Consortium of the U.S.; Alan Thornhill, chief environmental officer, U.S. Department of the Interior's Bureau of Ocean Energy Management; and Fran Ulmer, chair, U.S. Arctic Research Commission. A plenary on the U.N. Convention on the Law of the Sea featured Ambassador David Balton, deputy assistant secretary for oceans and fisheries, U.S. Department of State; and Rear Admiral Frederick Kenney Jr., judge advocate general and chief counsel, U.S. Coast Guard. The plenary on Science and the 21st Century featured Phil Keslin, chief technology officer, small lab within Google.

Energy absorption capabilities of composite sandwich panels under blast loads

NASA Astrophysics Data System (ADS)

Sankar Ray, Tirtha

, ET) was suggested to compare energy absorption capabilities of the structures under blast loading. In addition, AEweb/ET (where AEweb is the energy absorbed by the middle core) was also employed to evaluate the energy absorption contribution from the web. Taking advantage of FEA and the simplified analytical model, the influences of material properties as well as core architectures and geometries on energy absorption capabilities (quantified by AET/ ET and AEweb/E T) were investigated through parametric studies. Results from the material property investigation indicated that density of the front face sheet and strength were most influential on the energy absorption capability of the composite sandwich panels under blast loading. The study to investigate the potential effectiveness of energy absorbed via inelastic deformation compared to energy absorbed via progressive failure indicated that for practical applications (where the position of bomb is usually unknown and the panel is designed to be the same anywhere), the energy absorption via inelastic deformation is the more efficient approach. Regarding the geometric optimization, it was found that a core architecture consisting of vertically-oriented webs was ideal. The optimum values for these parameters can be generally described as those which cause the most inelasticity, but not failure, of the face sheets and webs.

Absorption in Sport: A Cross-Validation Study

PubMed Central

Koehn, Stefan; Stavrou, Nektarios A. M.; Cogley, Jeremy; Morris, Tony; Mosek, Erez; Watt, Anthony P.

2017-01-01

Absorption has been identified as readiness for experiences of deep involvement in the task. Conceptually, absorption is a key psychological construct, incorporating experiential, cognitive, and motivational components. Although, no operationalization of the construct has been provided to facilitate research in this area, the purpose of this research was the development and examination of the psychometric properties of a sport-specific measure of absorption that evolved from the use of the modified Tellegen Absorption Scale (MODTAS; Jamieson, 2005) in mainstream psychology. The study aimed to provide evidence of the psychometric properties, reliability, and validity of the Measure of Absorption in Sport Contexts (MASCs). The psychometric examination included a calibration sample from Scotland and a cross-validation sample from Australia using a cross-sectional design. The item pool was developed based on existing items from the modified Tellegen Absorption Scale (Jamieson, 2005). The MODTAS items were reworded and translated into a sport context. The Scottish sample consisted of 292 participants and the Australian sample of 314 participants. Congeneric model testing and confirmatory factor analysis for both samples and multi-group invariance testing across samples was used. In the cross-validation sample the MASC subscales showed acceptable internal consistency and construct reliability (≥0.70). Excellent fit indices were found for the final 18-item, six-factor measure in the cross-validation sample, χ(120)2 = 197.486, p < 0.001; CFI = 0.957; TLI = 0.945; RMSEA = 0.045; SRMR = 0.044. Multi-group invariance testing revealed no differences in item meaning, except for two items. The MASC and the Dispositional Flow Scale-2 showed moderate-to-strong positive correlations in both samples, r = 0.38, p < 0.001 and r = 0.42, p < 0.001, supporting the external validity of the MASC. This article provides initial evidence in support of the psychometric properties

An Investigation of the 3-μm Feature in M-Type Asteroids

NASA Astrophysics Data System (ADS)

Landsman, Zoe A.; Campins, H.; Hargrove, K.; Pinilla-Alonso, N.; Emery, J.; Ziffer, J.

2013-10-01

The M-type asteroids had originally been interpreted as the disrupted iron cores of differentiated bodies by spectral analogy with the NiFe meteorites. More detailed studies have since indicated a range of compositions. In particular, the presence of a 3-µm feature, diagnostic of hydration, detected in more than 35% of surveyed M-type asteroids (Jones et al. 1990, Rivkin et al. 1995, 2000) has challenged the notion that these bodies are all metallic. Spectroscopy in the 0.8 - 2.5 µm region has revealed absorption features due to mafic silicates and hydroxides or phyllosilicates (Fornasier et al. 2010, Hardersen et al. 2006, 2010, Ockert-Bell et al. 2010). Radar studies have shown that most M-types are not likely to be iron cores, but they typically have a higher metal content than average (Shepard et al. 2010). Taken together, these results paint a fairly confounding picture of the M-type asteroids. While several interpretations have been suggested, more work is needed to clarify the mineralogy of these bodies. We have started a new spectroscopic study of the M asteroids in the 2 - 4 µm region. We seek to characterize the shape, band center, and band depth of the 3-µm feature where it is present, as these measures are indicative of the type and extent of hydration present on asteroids (Lebofsky et al. 1985, Rivkin et al. 2002, Takir & Emery 2012, Volguardsen et al. 2007). With this work, we hope to shed new light on the origin of hydration on M asteroids and its context within their mineralogy and thermal evolution. In July 2013, we obtained 2 - 4 µm spectra for 69 Hesperia, 136 Austria, and 261 Prymno with the SpeX at NASA’s IRTF, and are in the process of reducing the data. We have also obtained 0.8 - 2.0 µm data for 261 Prymno using the NICS at the TNG in February 2013. We report the presence of an absorption feature near 0.9 µm in Prymno’s spectrum, indicating a partially silicate composition. Based on spectral, physical and orbital similarities to

Interactions of praseodymium and neodymium with nucleosides and nucleotides: absorption difference and comparative absorption spectral study.

PubMed

Misra, S N; Anjaiah, K; Joseph, G; Abdi, S H

1992-02-01

The interactions of praseodymium(III) and neodymium(III) with nucleosides and nucleotides have been studied in different stoichiometry in water and water-DMF mixtures by employing absorption difference and comparative absorption spectrophotometry. The 4f-4f bands were analysed by linear curve analysis followed by gaussian curve analysis, and various spectral parameters were computed, using partial and multiple regression method. The magnitude of changes in both energy interaction and intensity were used to explore the degree of outer and inner sphere coordination, incidence of covalency and the extent of metal 4f-orbital involvement in chemical bonding. Crystalline complexes of the type [Ln(nucleotide)2(H2O)2]- (where nucleotide--GMP or IMP) were characterized by IR, 1H NMR, 31P NMR data. These studies indicated that the binding of the nucleotide is through phosphate oxygen in a bidentate manner and the complexes undergo substantial ionisation in aqueous medium, thereby supporting the observed weak 4f-4f bands and lower values for nephelauxetic effect (1-beta), bonding (b) and covalency (delta) parameters derived from coulombic and spin orbit interaction parameters.

Escalator design features evaluation

NASA Technical Reports Server (NTRS)

Zimmerman, W. F.; Deshpande, G. K.

1982-01-01

Escalators are available with design features such as dual speed (90 and 120 fpm), mat operation and flat steps. These design features were evaluated based on the impact of each on capital and operating costs, traffic flow, and safety. A human factors engineering model was developed to analyze the need for flat steps at various speeds. Mat operation of escalators was found to be cost effective in terms of energy savings. Dual speed operation of escalators with the higher speed used during peak hours allows for efficient operation. A minimum number of flat steps required as a function of escalator speed was developed to ensure safety for the elderly.

Geochemistry of Soil Samples from 50 Solution-Collapse Features on the Coconino Plateau, Northern Arizona

USGS Publications Warehouse

Van Gosen, Bradley S.; Wenrich, Karen J.

1991-01-01

Soil sampling surveys were conducted during 1984-1986 across 50 solution-collapse features exposed on the Coconino Plateau of northern Arizona in order to determine whether soil geochemistry can be used to distinguish mineralized breccia pipes from unmineralized collapse features. The 50 sampled features represent the variety of collapse features that crop out on plateau surfaces in northwestern Arizonaoodeeplyorooted solution-collapse breccia pipes, near-surface gypsum collapses, and sinkholes. Of the 50 features that were sampled in this study, 3 are confirmed breccia pipes that contain significant uranium and base-metal minerals, I is believed to be a sinkhole with no economic potential, and 4 are stratabound copper deposits whose possible relationship to breccia pipes is yet to be determined. The remaining collapse features are suspected to overlie breccia pipes, although some of these may represent near surface gypsum collapse features. However, no exploratory drilling results or breccia exposures exist to indicate their underlying structure. The low cost and ease of soil sampling suggested that this technique be evaluated for breccia pipe exploration. This report provides the locations and geochemical results for the soil sampling surveys and brief descriptions of the 50 collapse features. The analytical results of almost 2,000 soil samples are provided in tabular hardcopy and dBase III Plus diskcopy format. The analytical data is provided in digital format to allow the reader to choose their own methods for evaluating the effectiveness of soil sampling over known and suspected breccia pipes. A pilot survey conducted over 17 collapse features in 1984 suggested that soil sampling might be useful in distinguishing mineralized breccia pipes from other circular features. Followup detailed surveys in 1985 and 1986 used a radial sampling pattern at each of 50 sites; at least one third of the samples were collected from areas outside of the collapse feature to

Near-infrared diode laser absorption diagnostic for temperature and water vapor in a scramjet combustor

NASA Astrophysics Data System (ADS)

Liu, Jonathan T. C.; Rieker, Gregory B.; Jeffries, Jay B.; Gruber, Mark R.; Carter, Campbell D.; Mathur, Tarun; Hanson, Ronald K.

2005-11-01

Tunable diode laser absorption measurements of gas temperature and water concentration were made at the exit of a model scramjet combustor fueled on JP-7. Multiplexed, fiber-coupled, near-infrared distributed feedback lasers were used to probe three water vapor absorption features in the 1.34 1.47 μm spectral region (2v1 and v1+v3 overtone bands). Ratio thermometry was performed using direct-absorption wavelength scans of isolated features at a 4-kHz repetition rate, as well as 2f wavelength modulation scans at a 2-kHz scan rate. Large signal-to-noise ratios demonstrate the ability of the optimally engineered optical hardware to reject beam steering and vibration noise. Successful measurements were made at full combustion conditions for a variety of fuel/air equivalence ratios and at eight vertical positions in the duct to investigate spatial uniformity. The use of three water vapor absorption features allowed for preliminary estimates of temperature distributions along the line of sight. The improved signal quality afforded by 2f measurements, in the case of weak absorption, demonstrates the utility of a scanned wavelength modulation strategy in such situations.

In vitro and in vivo percutaneous absorption of retinol from cosmetic formulations: Significance of the skin reservoir and prediction of systemic absorption

SciTech Connect

Yourick, Jeffrey J.; Jung, Connie T.; Bronaugh, Robert L.

2008-08-15

The percutaneous absorption of retinol (Vitamin A) from cosmetic formulations was studied to predict systemic absorption and to understand the significance of the skin reservoir in in vitro absorption studies. Viable skin from fuzzy rat or human subjects was assembled in flow-through diffusion cells for in vitro absorption studies. In vivo absorption studies using fuzzy rats were performed in glass metabolism cages for collection of urine, feces, and body content. Retinol (0.3%) formulations (hydroalcoholic gel and oil-in-water emulsion) containing {sup 3}H-retinol were applied and absorption was measured at 24 or 72 h. All percentages reported are % of applied dose.more » In vitro studies using human skin and the gel and emulsion vehicles found 0.3 and 1.3% retinol, respectively, in receptor fluid at 24 h. Levels of absorption in the receptor fluid increased over 72 h with the gel and emulsion vehicles. Using the gel vehicle, in vitro rat skin studies found 23% in skin and 6% in receptor fluid at 24 h, while 72-h studies found 18% in skin and 13% in receptor fluid. Thus, significant amounts of retinol remained in rat skin at 24 h and decreased over 72 h, with proportional increases in receptor fluid. In vivo rat studies with the gel found 4% systemic absorption of retinol after 24 h and systemic absorption did not increase at 72 h. Retinol remaining in rat skin after in vivo application was 18% and 13% of the applied dermal dose after 24 and 72 h, respectively. Similar observations were made with the oil-in water emulsion vehicle in the rat. Retinol formed a reservoir in rat skin both in vivo and in vitro. Little additional retinol was bioavailable after 24 h. Comparison of these in vitro and in vivo results for absorption through rat skin indicates that the 24-h in vitro receptor fluid value accurately estimated 24-h in vivo systemic absorption. Therefore, the best single estimate of retinol systemic absorption from in vitro human skin studies is the 24-h

Fluid absorption solar energy receiver

NASA Technical Reports Server (NTRS)

Bair, Edward J.

1993-01-01

A conventional solar dynamic system transmits solar energy to the flowing fluid of a thermodynamic cycle through structures which contain the gas and thermal energy storage material. Such a heat transfer mechanism dictates that the structure operate at a higher temperature than the fluid. This investigation reports on a fluid absorption receiver where only a part of the solar energy is transmitted to the structure. The other part is absorbed directly by the fluid. By proportioning these two heat transfer paths the energy to the structure can preheat the fluid, while the energy absorbed directly by the fluid raises the fluid to its final working temperature. The surface temperatures need not exceed the output temperature of the fluid. This makes the output temperature of the gas the maximum temperature in the system. The gas can have local maximum temperatures higher than the output working temperature. However local high temperatures are quickly equilibrated, and since the gas does not emit radiation, local high temperatures do not result in a radiative heat loss. Thermal radiation, thermal conductivity, and heat exchange with the gas all help equilibrate the surface temperature.

Controlling coulomb interactions in infrared stereometamaterials for unity light absorption

NASA Astrophysics Data System (ADS)

Mudachathi, Renilkumar; Moritake, Yuto; Tanaka, Takuo

2018-05-01

We investigate the influence of near field interactions between the constituent 3D split ring resonators on the absorbance and resonance frequency of a stereo metamaterial based perfect light absorber. The experimental and theoretical analyses reveal that the magnetic resonance red shifts and broadens for both the decreasing vertical and lateral separations of the constituents within the metamaterial lattice, analogous to plasmon hybridization. The strong interparticle interactions for higher density reduce the effective cross-section per resonator, which results in weak light absorption observed in both experimental and theoretical analyses. The red shift of the magnetic resonance with increasing lattice density is an indication of the dominating electric dipole interactions and we analyzed the metamaterial system in an electrostatic point of view to explain the observed resonance shift and decreasing absorption peak. From these analyses, we found that the fill factor introduces two competing factors determining the absorption efficiency such as coulomb interactions between the constituent resonators and their number density in a given array structure. We predicted unity light absorption for a fill factor of 0.17 balancing these two opposing factors and demonstrate an experimental absorbance of 99.5% at resonance with our 3D device realized using residual stress induced bending of 2D patterns.

Intestinal absorption of chromium as affected by wheat bran

SciTech Connect

Keim, K.S.; Holloway, C.L.; Hegsted, M.

1986-03-01

This study was designed to investigate the influence of dietary fiber, as found in wheat bran, on the absorption of chromium. Twenty male Sprague-Dawley rats were divided into two groups of 10. The control was fed a semi-purified diet containing casein, methionine, cornstarch, sucrose, corn oil, mineral and vitamin mix, and choline bitartrate. The experimental group was fed the same diet but with soft red winter wheat bran added to a level of 35% of the diet at the expense of sucrose. To determine chromium absorption and uptake by selected tissues, rats were fasted for 24 hr, fed 5 gmore » of the respective diet, 2 hr later intubated with 100..mu..Ci of Cr-51of sacrificed 24 hr later. The rats wee housed in metabolic cages after the Cr-51 intubation. The addition of wheat brand to the diet did not significantly affect chromium absorption as measured by percent dose of Cr-51 in the 24 hr urine. The percent dose in the control group was 0.68 +/- 0.20% (mean +/- SEM) and in the experimental group 0.63 +/- 0.24% (mean +/-SEM) (N.S.). The cr-51 uptake of liver, spleen, jejunum, and blood was not statistically different between groups. These results indicate that dietary fiber as found in wheat bran does not impair intestinal absorption of chromium.« less

Pancake Feature on Ceres

NASA Image and Video Library

2015-03-02

Some might see a pancake, and others a sand dollar, in this new image from NASA Dawn mission. Astronomers are puzzling over a mysterious large circular feature located south of the equator and slightly to the right of center in this view.

Integrated Education. Feature Issue.

ERIC Educational Resources Information Center

York, Jennifer, Ed.; Vandercook, Terri, Ed.

1988-01-01

This "feature issue" provides various perspectives on a number of integrated education topics, including successful integration practices and strategies, the changing roles of teachers, the appropriate role of research, the history and future of integrated education, and the realization of dreams of life in the mainstream for children with severe…

Assistive Technologies, Feature Issue.

ERIC Educational Resources Information Center

Wobschall, Rachel, Ed.; Lakin, Charlie, Ed.

1995-01-01

This feature issue of a newsletter on community integration of individuals with developmental disabilities considers the role of assistive technologies. It describes efforts to utilize consumer direction, public policy, creativity, energy, and professional know-how in the pursuit of technology-based opportunities to enhance community inclusion,…

Terahertz Absorption and Circular Dichroism Spectroscopy of Solvated Biopolymers

NASA Astrophysics Data System (ADS)

Xu, Jing; Plaxco, Kevin; Allen, S. James

2006-03-01

Biopolymers are expected to exhibit broad spectral features in the terahertz frequency range, corresponding to their functionally relevant, global and sub-global collective vibrational modes with ˜ picosecond timescale. Recent advances in terahertz technology have stimulated researchers to employ terahertz absorption spectroscopy to directly probe these postulated collective modes. However, these pioneering studies have been limited to dry and, at best, moist samples. Successful isolation of low frequency vibrational activities of solvated biopolymers in their natural water environment has remained elusive, due to the overwhelming attenuation of the terahertz radiation by water. Here we have developed a terahertz absorption and circular dichroism spectrometer suitable for studying biopolymers in biologically relevant water solutions. We have precisely isolated, for the first time, the terahertz absorption of solvated prototypical proteins, Bovine Serum Albumin and Lysozyme, and made important direct comparison to the existing molecular dynamic simulations and normal mode calculations. We have also successfully demonstrated the magnetic circular dichroism in semiconductors, and placed upper bounds on the terahertz circular dichroism signatures of prototypical proteins in water solution.

Estimation of water absorption coefficient using the TDR method

NASA Astrophysics Data System (ADS)

Suchorab, Zbigniew; Majerek, Dariusz; Brzyski, Przemysław; Sobczuk, Henryk; Raczkowski, Andrzej

2017-07-01

Moisture accumulation and transport in the building barriers is an important feature that influences building performance, causing serious exploitation problems as increased energy use, mold and bacteria growth, decrease of indoor air parameters that may lead to sick building syndrome (SBS). One of the parameters that is used to describe moisture characteristic of the material is water absorption coefficient being the measure of capillary behavior of the material as a function of time and the surface area of the specimen. As usual it is determined using gravimetric methods according to EN 1925:1999 standard. In this article we demonstrate the possibility of determination of water absorption coefficient of autoclaved aerated concrete (AAC) using the Time Domain Reflectometry (TDR) method. TDR is an electric technique that had been adopted from soil science and can be successfully used for real-time monitoring of moisture transport in building materials and envelopes. Data achieved using TDR readouts show high correlation with standard method of moisture absorptivity coefficient determination.

A Low-Cost Quantitative Absorption Spectrophotometer

ERIC Educational Resources Information Center

Albert, Daniel R.; Todt, Michael A.; Davis, H. Floyd

2012-01-01

In an effort to make absorption spectrophotometry available to high school chemistry and physics classes, we have designed an inexpensive visible light absorption spectrophotometer. The spectrophotometer was constructed using LEGO blocks, a light emitting diode, optical elements (including a lens), a slide-mounted diffraction grating, and a…

Do Atoms Really "Emit" Absorption Lines?

ERIC Educational Resources Information Center

Brecher, Kenneth

1991-01-01

Presents three absorption line sources that enhance student understanding of the phenomena associated with the interaction of light with matter and help dispel the misconception that atoms "emit" absorption lines. Sources include neodymium, food coloring and other common household liquids, and fluorescent materials. (MDH)

Absorption of sound by tree bark

Treesearch

G. Reethof; L. D. Frank; O. H. McDaniel

1976-01-01

Laboratory tests were conducted with a standing wave tube to measure the acoustic absorption of normally incident sound by the bark of six species of trees. Twelve bark samples, 10 cm in diameter, were tested. Sound of seven frequencies between 400 and 1600 Hz was used in the measurements. Absorption was generally about 5 percent; it exceeded 10 percent for only three...

Photoelectric absorption cross sections with variable abundances

NASA Technical Reports Server (NTRS)

Balucinska-Church, Monika; Mccammon, Dan

1992-01-01

Polynomial fit coefficients have been obtained for the energy dependences of the photoelectric absorption cross sections of 17 astrophysically important elements. These results allow the calculation of X-ray absorption in the energy range 0.03-10 keV in material with noncosmic abundances.

Low absorptance porcelain-on-aluminum coating

NASA Technical Reports Server (NTRS)

Leggett, H.

1979-01-01

Porcelain thermal-control coating for aluminum sheet and foil has solar absorptance of 0.22. Specially formulated coating absorptance is highly stable, changing only 0.03 after 1,000 hours of exposure to simulated sunlight and can be applied by standard commercial methods.

Iron absorption from intrinsically-labeled lentils

USDA-ARS?s Scientific Manuscript database

Low iron (Fe) absorption from important staple foods may contribute to Fe deficiency in developing countries. To date, there are few studies examining the Fe bioavailability of pulse crops as commonly prepared and consumed by humans. The objectives of this study were to characterize the Fe absorpt...

High-Absorptance Radiative Heat Sink

NASA Technical Reports Server (NTRS)

Cafferty, T.

1983-01-01

Absorptance of black-painted open-cell aluminum honeycomb improved by cutting honeycomb at angle or bias rather than straight across. This ensures honeycomb cavities escapes. At each reflection radiation attenuated by absorption. Applications include space-background simulators, space radiators, solar absorbers, and passive coolers for terrestrial use.

High enthalpy arc-heated plasma flow diagnostics by tunable diode laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Lin, Xin; Chen, Lianzhong; Zeng, Hui; Ou, Dongbin; Dong, Yonghui

2017-05-01

This paper reports the laser absorption measurements of atomic oxygen in the FD04 arc-heater at China Academy of Aerospace Aerodynamics (CAAA). An atomic oxygen absorption line at 777.19 nm is utilizied for detecting the population of electronically excited oxygen atom in an air plasma flow. A scanned-wavelength direct absorption mode is used in this study. The laser is scanned in wavelength across the absorption feature at a rate of 200 Hz. Under the assumption of thermal equilibrium, time-resolved temperature measurements are obtained on one line-of-sight in the arc-heater. The good agreement of the temperature inferred from the sonic throat method suggests the equilibrium assumption is valid. These results illustrate the feasibility of the diode laser sensors for flow parameters in high enthalpy arc-heated facilities.

Ultra-bright red-emitting photostable perylene bisimide dyes: new indicators for ratiometric sensing of high pH or carbon dioxide.

PubMed

Pfeifer, David; Klimant, Ingo; Borisov, Sergey M

2018-05-08

New pH sensitive perylene bisimide indicator dyes were synthesised and used for fabrication of optical sensors. The highly photostable dyes show absorption/emission bands in the red/near-infrared (NIR) region of the electromagnetic spectrum, high molar absorption coefficients (up to 100 000 M-1 cm-1) and fluorescence quantum yields close to unity. The absorption and emission spectra show strong bathochromic shift upon deprotonation of imidazole nitrogen which makes the dyes promising as ratiometric fluorescent indicators. Physical entrapment of the indicators into polyurethane hydrogel enables pH determination in alkaline pH. It is also shown that plastic carbon dioxide solid state sensor can be manufactured via immobilization of the pH indicator in a hydrophilic polymer, along with a quaternary ammonium base. The influence of plasticizer, different lipophilic bases and humidity on the sensitivity of the sensor material were systematically investigated. The disubstituted perylene, particularly, features two deprotonation equilibria enabling sensing over a very broad range from 0.5 to 1000 hPa pCO2. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Food Ingredients That Inhibit Cholesterol Absorption

PubMed Central

Jesch, Elliot D.; Carr, Timothy P.

2017-01-01

Cholesterol is a vital component of the human body. It stabilizes cell membranes and is the precursor of bile acids, vitamin D and steroid hormones. However, cholesterol accumulation in the bloodstream (hypercholesterolemia) can cause atherosclerotic plaques within artery walls, leading to heart attacks and strokes. The efficiency of cholesterol absorption in the small intestine is of great interest because human and animal studies have linked cholesterol absorption with plasma concentration of total and low density lipoprotein cholesterol. Cholesterol absorption is highly regulated and influenced by particular compounds in the food supply. Therefore, it is desirable to learn more about natural food components that inhibit cholesterol absorption so that food ingredients and dietary supplements can be developed for consumers who wish to manage their plasma cholesterol levels by non-pharmacological means. Food components thus far identified as inhibitors of cholesterol absorption include phytosterols, soluble fibers, phospholipids, and stearic acid. PMID:28702423

A SEARCH FOR Hα ABSORPTION AROUND KELT-3 b AND GJ 436 b

SciTech Connect

Cauley, P. Wilson; Redfield, Seth; Jensen, Adam G., E-mail: pcauley@wesleyan.edu

2017-02-01

Observations of extended atmospheres around hot planets have generated exciting results concerning the dynamics of escaping planetary material. The configuration of the escaping planetary gas can result in asymmetric transit features, producing both pre- and post-transit absorption in specific atomic transitions. Measuring the velocity and strength of the absorption can provide constraints on the mass loss mechanism, and potentially clues to the interactions between the planet and the host star. Here we present a search for H α absorption in the circumplanetary environments of the hot planets KELT-3 b and GJ 436 b. We find no evidence for absorption aroundmore » either planet at any point during the two separate transit epochs for which each system was observed. We provide upper limits on the radial extent and density of the excited hydrogen atmospheres around both planets. The null detection for GJ 436 b contrasts with the strong Ly α absorption measured for the same system, suggesting that the large cloud of neutral hydrogen is almost entirely in the ground state. The only confirmed exoplanetary H α absorption to date has been made around the active star HD 189733 b. KELT-3 and GJ 436 are less active than HD 189733, hinting that exoplanet atmospheres exposed to EUV photons from active stars are better suited for detection of H α absorption.« less

Unified analysis of optical absorption spectra of carotenoids based on a stochastic model.

PubMed

Uragami, Chiasa; Saito, Keisuke; Yoshizawa, Masayuki; Molnár, Péter; Hashimoto, Hideki

2018-05-03

The chemical structures of the carotenoid molecules are very simple and one might think that the electronic feature of it is easily predicted. However, it still has so much unknown information except the correlation between the electronic energy state and the length of effective conjugation chain of carotenoids. To investigate the electronic feature of the carotenoids, the most essential method is measuring the optical absorption spectra, but simulating it from the resonance Raman spectra is also the effective way. From this reason, we studied the optical absorption spectra as well as resonance Raman spectra of 15 different kinds of cyclic carotenoid molecules, recorded in tetrahydrofuran (THF) solutions at room temperature. The whole band shapes of the absorption spectra of all these carotenoid molecules were successfully simulated based on a stochastic model using Brownian oscillators. The parameters obtained from the simulation made it possible to discuss the intermolecular interaction between carotenoids and solvent THF molecules quantitatively. Copyright © 2018. Published by Elsevier Inc.

The ÖX˜ absorption of vinoxy radical revisited: Normal and Herzberg-Teller bands observed via cavity ringdown spectroscopy

NASA Astrophysics Data System (ADS)

Thomas, Phillip S.; Chhantyal-Pun, Rabi; Kline, Neal D.; Miller, Terry A.

2010-03-01

The ÖX˜ electronic absorption spectrum of vinoxy radical has been investigated using room temperature cavity ringdown spectroscopy. Analysis of the observed bands on the basis of computed vibrational frequencies and rotational envelopes reveals that two distinct types of features are present with comparable intensities. The first type corresponds to "normal" allowed electronic transitions to the origin and symmetric vibrations in the à state. The second type is interpreted in terms of excitations to asymmetric à state vibrations, which are only vibronically allowed by Herzberg-Teller coupling to the B˜ state. Results of electronic structure calculations indicate that the magnitude of the Herzberg-Teller coupling is appropriate to produce vibronically induced transitions with intensities comparable to those of the normal bands.

Performance of Ultrathin Silicon Solar Microcells with Nanostructures of Relief Formed by Soft Imprint Lithography for Broad Band Absorption Enhancement

SciTech Connect

Shir, Daniel J.; Yoon, Jongseung; Chanda, Debashis

2010-08-11

Recently developed classes of monocrystalline silicon solar microcells can be assembled into modules with characteristics (i.e., mechanically flexible forms, compact concentrator designs, and high-voltage outputs) that would be impossible to achieve using conventional, wafer-based approaches. This paper presents experimental and computational studies of the optics of light absorption in ultrathin microcells that include nanoscale features of relief on their surfaces, formed by soft imprint lithography. Measurements on working devices with designs optimized for broad band trapping of incident light indicate good efficiencies in energy production even at thicknesses of just a few micrometers. These outcomes are relevant not only tomore » the microcell technology described here but also to other photovoltaic systems that benefit from thin construction and efficient materials utilization.« less

A simulation study on terahertz absorption of liquid crystal mixture E7

NASA Astrophysics Data System (ADS)

Dong, Jian-qi; Cheng, Wen-qi; Li, Meng-ge; Wang, Kai-li; Chen, Ze-zhang; Ma, Heng

2017-09-01

A simulation work on a broad THz absorption of liquid crystal mixture E7 consisting of 5CB, 7CB, 8OCB and 5CT is reported. Based on the density functional theory, the molecular structures of the monomers were optimized and calculated using the Gaussian package with base set B3LYP and 6-311g. The results indicate that the simulation of the characteristic absorption spectra is accurate compared to the experimental and literature report in the infrared band. By analyzing contribution of the benzene ring, C-O and alkyl bonds on THz absorption, it is found that there are no significant effects from the cyano group and the alkyl radical. The addition of a benzene ring leads to an increase in absorption intensity and redshift. By discussing the atomic mass distribution and the structural symmetry of the monomers, a reason for the strong THz absorption of 8OCB is proposed.

Low-refractive-index dye-aggregate films with small absorption based on anomalous dispersion.

PubMed

Wakamatsu, Takashi; Watanabe, Keita; Saito, Kazuhiro

2005-02-20

Complex-refractive-index spectra of Squarylium (SQ) dye-aggregate films deposited upon metal films have been investigated by measurements of properties of the films including absorption spectra (AS) and attenuated total reflection. Complex refractive indices are estimated by Kramers-Kronig analysis for the AS and by a theoretical curve-fitting analysis for attenuated total reflection. The dye-aggregate films exhibited an absorption that was blueshifted from that of a monomer, as a result of the H-aggregate formation of SQ molecules, and had a changing refractive index with anomalous dispersion about the H-absorption band. From both measurements of the SQ films it was found that there is a region of low absorption in the short-wavelength side of the absorption band and that the refractive index there is lower than that of glass.

Low-refractive-index dye-aggregate films with small absorption based on anomalous dispersion

NASA Astrophysics Data System (ADS)

Wakamatsu, Takashi; Watanabe, Keita; Saito, Kazuhiro

2005-02-01

Complex-refractive-index spectra of Squarylium (SQ) dye-aggregate films deposited upon metal films have been investigated by measurements of properties of the films including absorption spectra (AS) and attenuated total reflection. Complex refractive indices are estimated by Kramers-Kronig analysis for the AS and by a theoretical curve-fitting analysis for attenuated total reflection. The dye-aggregate films exhibited an absorption that was blueshifted from that of a monomer, as a result of the H-aggregate formation of SQ molecules, and had a changing refractive index with anomalous dispersion about the H-absorption band. From both measurements of the SQ films it was found that there is a region of low absorption in the short-wavelength side of the absorption band and that the refractive index there is lower than that of glass.

Two-photon absorption spectrum of the photoinitiator Lucirin TPO-L

NASA Astrophysics Data System (ADS)

Mendonca, C. R.; Correa, D. S.; Baldacchini, T.; Tayalia, P.; Mazur, E.

2008-03-01

Two-photon absorption induced polymerization provides a powerful method for the fabrication of intricate three-dimensional microstructures. Recently, Lucirin TPO-L was shown to be a photoinitiator with several advantageous properties for two-photon induced polymerization. Here we measure the two-photon absorption cross-section spectrum of Lucirin TPO-L, which presents a maximum of 1.2 GM at 610 nm. Despite its small two-photon absorption cross-section, it is possible to fabricate excellent microstructures by two-photon polymerization due to the high polymerization quantum yield of Lucirin TPO-L. These results indicate that optimization of the two-photon absorption cross-section is not the only material parameter to be considered when searching for new photoinitiators for microfabrication via two-photon absorption.

Feature Centrality and Property Induction

ERIC Educational Resources Information Center

Hadjichristidis, Constantinos; Sloman, Steven; Stevenson, Rosemary; Over, David

2004-01-01

A feature is central to a concept to the extent that other features depend on it. Four studies tested the hypothesis that people will project a feature from a base concept to a target concept to the extent that they believe the feature is central to the two concepts. This centrality hypothesis implies that feature projection is guided by a…

Multi-wavelength differential absorption measurements of chemical species

NASA Astrophysics Data System (ADS)

Brown, David M.

The probability of accurate detection and quantification of airborne species is enhanced when several optical wavelengths are used to measure the differential absorption of molecular spectral features. Characterization of minor atmospheric constituents, biological hazards, and chemical plumes containing multiple species is difficult when using current approaches because of weak signatures and the use of a limited number of wavelengths used for identification. Current broadband systems such as Differential Optical Absorption Spectroscopy (DOAS) have either limitations for long-range propagation, or require transmitter power levels that are unsafe for operation in urban environments. Passive hyperspectral imaging systems that utilize absorption of solar scatter at visible and infrared wavelengths, or use absorption of background thermal emission, have been employed routinely for detection of airborne chemical species. Passive approaches have operational limitations at various ranges, or under adverse atmospheric conditions because the source intensity and spectrum is often an unknown variable. The work presented here describes a measurement approach that uses a known source of a low transmitted power level for an active system, while retaining the benefits of broadband and extremely long-path absorption operations. An optimized passive imaging system also is described that operates in the 3 to 4 mum window of the mid-infrared. Such active and passive instruments can be configured to optimize the detection of several hydrocarbon gases, as well as many other species of interest. Measurements have provided the incentive to develop algorithms for the calculations of atmospheric species concentrations using multiple wavelengths. These algorithms are used to prepare simulations and make comparisons with experimental results from absorption data of a supercontinuum laser source. The MODTRAN model is used in preparing the simulations, and also in developing additional

Monitoring Telluric Absorption with CAMAL

NASA Astrophysics Data System (ADS)

Baker, Ashley D.; Blake, Cullen H.; Sliski, David H.

2017-08-01

Ground-based astronomical observations may be limited by telluric water vapor absorption, which is highly variable in time and significantly complicates both spectroscopy and photometry in the near-infrared (NIR). To achieve the sensitivity required to detect Earth-sized exoplanets in the NIR, simultaneous monitoring of precipitable water vapor (PWV) becomes necessary to mitigate the impact of variable telluric lines on radial velocity measurements and transit light curves. To address this issue, we present the Camera for the Automatic Monitoring of Atmospheric Lines (CAMAL), a stand-alone, inexpensive six-inch aperture telescope dedicated to measuring PWV at the Fred Lawrence Whipple Observatory on Mount Hopkins. CAMAL utilizes three narrowband NIR filters to trace the amount of atmospheric water vapor affecting simultaneous observations with the MINiature Exoplanet Radial Velocity Array (MINERVA) and MINERVA-Red telescopes. Here, we present the current design of CAMAL, discuss our data analysis methods, and show results from 11 nights of PWV measurements taken with CAMAL. For seven nights of data we have independent PWV measurements extracted from high-resolution stellar spectra taken with the Tillinghast Reflector Echelle Spectrometer (TRES) also located on Mount Hopkins. We use the TRES spectra to calibrate the CAMAL absolute PWV scale. Comparisons between CAMAL and TRES PWV estimates show excellent agreement, matching to within 1 mm over a 10 mm range in PWV. Analysis of CAMAL’s photometric precision propagates to PWV measurements precise to better than 0.5 mm in dry (PWV < 4 mm) conditions. We also find that CAMAL-derived PWVs are highly correlated with those from a GPS-based water vapor monitor located approximately 90 km away at Kitt Peak National Observatory, with a root mean square PWV difference of 0.8 mm.

Exocomet Orbit Fitting: Accelerating Coma Absorption During Transits of β Pictoris

NASA Astrophysics Data System (ADS)

Kennedy, Grant M.

2018-06-01

Comets are a remarkable feature in our night sky, visible on their passage through the inner Solar system as the Sun's energy sublimates ices and liberates surface material, generating beautiful comae, dust, and ion tails. Comets are also thought to orbit other stars, and are the most promising interpretation of sporadic absorption features (i.e. transits) seen in spectra of stars such as β Pictoris and 49 Ceti. These "exocomets" are thought to form and evolve in the same way as in the Solar system, and as in the Solar system we may gain insight into their origins by deriving their orbits. In the case of β Pictoris, orbits have been estimated indirectly, using the radial velocity of the absorption features coupled with a physical evaporation model to estimate the stellocentric distance at transit dtr. Here, we note that the inferred dtr imply that some absorption signatures should accelerate over several hours, and show that this acceleration is indeed seen in HARPS spectra. This new constraint means that orbital characteristics can be obtained directly, and the pericentre distance and longitude constrained when parabolic orbits are assumed. The results from fitting orbits to 12 accelerating features, and a handful of non-accelerating ones, are in broad agreement with previous estimates based on an evaporation model, thereby providing some validation of the exocomet hypothesis. A prediction of the evaporation model, that coma absorption is deeper for more distant transits, is also seen here.

Aerosol scattering and absorption modulation transfer function

NASA Astrophysics Data System (ADS)

Sadot, Dan; Kopeika, Norman S.

1993-08-01

Recent experimental measurements of overall atmospheric modulation transfer function (MTF) indicate significant difference between the turbulence and overall atmospheric MTFs, except often at midday when turbulence is strong. We suggest here a physical explanation for those results which essentially relates to what we call a practical instrumentation-based atmospheric aerosol MTF which is a modification of the classical aerosol MTF theory. It is shown that system field-of-view and dynamic range affect strongly aerosol and overall atmospheric MTFs. It is often necessary to choose between MTF and SNR depending upon dynamic range requirements. Also, a new approach regarding aerosol absorption is presented. It is shown that aerosol-absorbed irradiance is spatial frequency dependent and enhances the degradation in image quality arising from received scattered light. This is most relevant for thermal imaging. An analytically corrected model for the aerosol MTF is presented which is relevant for imaging. An important conclusion is that the aerosol MTF is often the dominant part in the actual overall atmospheric MTF all across the optical spectral region.

Two-Photon Absorption Based Nanoscopic Velocimeter

NASA Astrophysics Data System (ADS)

Wang, Audrey; Abdalrahman, Akrm; Deng, Jianyu; Wang, Guiren

2017-11-01

Most velocimeters in micro/nanofluidics rely on particles as flow tracers, such as micro Particle Image Velocimetry (μPIV). However, for many microflows, such as electrokinetic and near wall flow, magnetophoresis, acoustophoresis, photophoresis and thermophoresis, particles have different velocity from their surrounding fluids. Although most molecular tracer based velocimeters can use neutral dye to measure average velocity, their temporal and spatial resolution are limited. Stimulated emission depletion (STED) based laser-induced fluorescence photobleaching anemometer (LIFPA), i.e. STED-LIFPA has achieved 70 nm spatial resolution. However, STED nanoscopy is very complicated for most users. Here we developed a two-photon absorption LIFPA (TP-LIFPA), which is relatively easier to operate. TP-LIFPA can take advantage of the two-photon microscopy to increase spatial resolution. We use a femtolaser to excite a dye. A microcapillary tube is used to test the feasibility of TP-LIFPA. TP-LIFPA can successfully measure the velocity profile in the capillary. The resolution of TP-LIFPA is estimated to be about 90 nm. The work indicates TP-LIFPA is a new promising nanoscopic velocimeter for interfacial flows, especially within 100 nm at the interfacial area between two phases in the future. The work was supported by NSF under Grant No. MRI CBET-1040227.

Interstellar Medium Absorption Profile Spectrograph (IMAPS)

NASA Technical Reports Server (NTRS)

Jenkins, E. B.

1985-01-01

The design and fabrication of an objective-grating echelle spectrograph to fly on sounding rockets and record spectra of stars from approximately 920 to 1120A with a resolving power lambda/delta lambda = 200,000 is discussed. The scientific purpose of the program is to observe, with ten times better velocity resolution than before, the plentiful absorption lines in this spectral region produced by atoms, ions and molecules in the interstellar medium. In addition, an important technical goal is to develop and flight-quality a new ultraviolet, photon-counting image sensor which has a windowless, opaque photocathode and a CCD bombarded directly by the accelerated photoelectrons. Except for some initial difficulties with the performance of CCDs, the development of the payload instrument is relatively straightforward and our overall design goals are satisfied. The first flight occurred in late 1984, but no data were obtained because of an inrush of air degraded the instrument's vacuum and caused the detector's high voltage to arc. A second flight in early 1985 was a complete success and obtained a spectrum of pi Sco. Data from this mission are currently being reduced; quick-look versions of the spectra indicate that excellent results will be obtained. Currently, the payload is being reconfigured to fly on a Spartan mission in 1988.

Constraining Cometary Crystal Shapes from IR Spectral Features

NASA Astrophysics Data System (ADS)

Wooden, D. H.; Lindsay, S.; Harker, D. E.; Kelley, M. S.; Woodward, C. E.; Murphy, J. R.

2013-12-01

A major challenge in deriving the silicate mineralogy of comets is ascertaining how the anisotropic nature of forsterite crystals affects the spectral features' wavelength, relative intensity, and asymmetry. Forsterite features are identified in cometary comae near 10, 11.05-11.2, 16, 19, 23.5, 27.5 and 33 μm [1-10], so accurate models for forsterite's absorption efficiency (Qabs) are a primary requirement to compute IR spectral energy distributions (SEDs, λFλ vs. λ) and constrain the silicate mineralogy of comets. Forsterite is an anisotropic crystal, with three crystallographic axes with distinct indices of refraction for the a-, b-, and c-axis. The shape of a forsterite crystal significantly affects its spectral features [13-16]. We need models that account for crystal shape. The IR absorption efficiencies of forsterite are computed using the discrete dipole approximation (DDA) code DDSCAT [11,12]. Starting from a fiducial crystal shape of a cube, we systematically elongate/reduce one of the crystallographic axes. Also, we elongate/reduce one axis while the lengths of the other two axes are slightly asymmetric (0.8:1.2). The most significant grain shape characteristic that affects the crystalline spectral features is the relative lengths of the crystallographic axes. The second significant grain shape characteristic is breaking the symmetry of all three axes [17]. Synthetic spectral energy distributions using seven crystal shape classes [17] are fit to the observed SED of comet C/1995 O1 (Hale-Bopp). The Hale-Bopp crystalline residual better matches equant, b-platelets, c-platelets, and b-columns spectral shape classes, while a-platelets, a-columns and c-columns worsen the spectral fits. Forsterite condensation and partial evaporation experiments demonstrate that environmental temperature and grain shape are connected [18-20]. Thus, grain shape is a potential probe for protoplanetary disk temperatures where the cometary crystalline forsterite formed. The

Fluid leak indicator

NASA Technical Reports Server (NTRS)

Anderson, George E. (Inventor); Loo, Shu (Inventor)

1989-01-01

A fluid leak indicator (30) for detecting and indicating leaks in visually inaccessible fluid tubing joints (20, 21), such as those obstructed by insulation (24), includes a bag system (25) and a wicking system (30) surrounding or wrapping the joints (20, 21) under the visual obstructing material (24). Leaking fluid is collected in the bag (25) or on the wicking material (34) where it is conducted along the wicking material (34) to a visibly accessible capturing transparent indicator bulb (35) for providing a visual indication of the leak without requiring a chemical change in the capturing indicator bulb (35).

Fluid leak indicator

NASA Technical Reports Server (NTRS)

Anderson, G. E.; Loo, S. (Inventor)

1985-01-01

A fluid leak indicator for detecting and indicating leaks in visually inaccessible fluid tubing joints, such as those obstructed by insulation includes a bag system and a wicking system surrounding or wrapping the joints under the visual obstructing material. Leaking fluid is collected in the bag or on the wicking material where it is conducted along the wicking material to a visily accessible capturing transparent indicator bulb for providing a visual indication of the leak without requiring a chemical change in the capturing indicator bulb.

Wild 2 Features

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site] Figure 1

These images taken by NASA's Stardust spacecraft highlight the diverse features that make up the surface of comet Wild 2. Side A (see Figure 1) shows a variety of small pinnacles and mesas seen on the limb of the comet. Side B (see Figure 1) shows the location of a 2-kilometer (1.2-mile) series of aligned scarps, or cliffs, that are best seen in the stereo images.

Wild 2 Features

NASA Image and Video Library

2004-06-17

These images taken by NASA's Stardust spacecraft highlight the diverse features that make up the surface of comet Wild 2, showing a variety of small pinnacles and mesas seen on the limb of the comet and the location of a 2-kilometer (1.2-mile) series of aligned scarps, or cliffs, that are best seen in the stereo images. http://photojournal.jpl.nasa.gov/catalog/PIA06284

Major depression with psychotic features

MedlinePlus

... this page: //medlineplus.gov/ency/article/000933.htm Major depression with psychotic features To use the sharing features on this page, please enable JavaScript. Major depression with psychotic features is a mental disorder in ...

Multiplicative Multitask Feature Learning

PubMed Central

Wang, Xin; Bi, Jinbo; Yu, Shipeng; Sun, Jiangwen; Song, Minghu

2016-01-01

We investigate a general framework of multiplicative multitask feature learning which decomposes individual task’s model parameters into a multiplication of two components. One of the components is used across all tasks and the other component is task-specific. Several previous methods can be proved to be special cases of our framework. We study the theoretical properties of this framework when different regularization conditions are applied to the two decomposed components. We prove that this framework is mathematically equivalent to the widely used multitask feature learning methods that are based on a joint regularization of all model parameters, but with a more general form of regularizers. Further, an analytical formula is derived for the across-task component as related to the task-specific component for all these regularizers, leading to a better understanding of the shrinkage effects of different regularizers. Study of this framework motivates new multitask learning algorithms. We propose two new learning formulations by varying the parameters in the proposed framework. An efficient blockwise coordinate descent algorithm is developed suitable for solving the entire family of formulations with rigorous convergence analysis. Simulation studies have identified the statistical properties of data that would be in favor of the new formulations. Extensive empirical studies on various classification and regression benchmark data sets have revealed the relative advantages of the two new formulations by comparing with the state of the art, which provides instructive insights into the feature learning problem with multiple tasks. PMID:28428735

Visualizing complex hydrodynamic features

NASA Astrophysics Data System (ADS)

Kempf, Jill L.; Marshall, Robert E.; Yen, Chieh-Cheng

1990-08-01

The Lake Erie Forecasting System is a cooperative project by university, private and governmental institutions to provide continuous forecasting of three-dimensional structure within the lake. The forecasts will include water velocity and temperature distributions throughout the body of water, as well as water level and wind-wave distributions at the lake's surface. Many hydrodynamic features can be extracted from this data, including coastal jets, large-scale thermocline motion and zones of upwelling and downwelling. A visualization system is being developed that will aid in understanding these features and their interactions. Because of the wide variety of features, they cannot all be adequately represented by a single rendering technique. Particle tracing, surface rendering, and volumetric techniques are all necessary. This visualization effortis aimed towards creating a system that will provide meaningful forecasts for those using the lake for recreational and commercial purposes. For example, the fishing industry needs to know about large-scale thermocline motion in order to find the best fishing areas and power plants need to know water intAke temperatures. The visualization system must convey this information in a manner that is easily understood by these users. Scientists must also be able to use this system to verify their hydrodynamic simulation. The focus of the system, therefore, is to provide the information to serve these diverse interests, without overwhelming any single user with unnecessary data.

Special Features of the Optical Absorption and Photoconductivity of Indium Monoselenide Upon Laser Excitation

NASA Astrophysics Data System (ADS)

Kyazym-Zade, A. G.; Salmanov, V. M.; Guseinov, A. G.; Mamedov, R. M.; Salmanova, A. A.; Akhmedova, F. Sh.

2018-02-01

The successive ionic layer adsorption and reaction (SILAR) method is used to prepare InSe thin films and InSe nanoparticles. Shapes and sizes of the obtained nanoparticles are investigated using a scanning electron microscope and an atomic force microscope. The main parameters of the examined structures, nanoparticle sizes (4-20 nm), and band gap ( E g = 1.60 eV) for nanoparticles with the least sizes are determined. Superfast (1.5·10-8 s) photocurrent relaxation and stimulated emission with line half-width of 8 Å have been observed upon exposure to laser radiation.

Fröhlich resonance in carbon nanospiroids and the 2175 Å interstellar absorption feature

NASA Astrophysics Data System (ADS)

Yastrebov, Sergey; Chekulaev, Maxim; Siklitskaya, Alexandra; Majewski, Jacek A.; Smith, Roger

2017-02-01

This paper demonstrates that a free electron gas model accurately simulates the spectral dependence of optical extinction spectra for carbon spiroids under the assumption that free electrons are confined in an homogeneous spherical particle owing to the delocalisation of π electrons that occurs in the actual spectral range. This effect can occur in the spiroid, rather than a spheroid (onion) due to the variable radii of the spiral turns as a function of distance from the centre, which are smaller than typical values for the spheroid.

Nonlinear bleaching, absorption, and scattering of 532-nm-irradiated plasmonic nanoparticles

SciTech Connect

Liberman, V.; Sworin, M.; Kingsborough, R. P.

2013-02-07

Single-pulse irradiation of Au and Ag suspensions of nanospheres and nanodisks with 532-nm 4-ns pulses has identified complex optical nonlinearities while minimizing material damage. For all materials tested, we observe competition between saturable absorption (SA) and reverse SA (RSA), with RSA behavior dominating for intensities above {approx}50 MW/cm{sup 2}. Due to reduced laser damage in single-pulse experiments, the observed intrinsic nonlinear absorption coefficients are the highest reported to date for Au nanoparticles. We find size dependence to the nonlinear absorption enhancement for Au nanoparticles, peaking in magnitude for 80-nm nanospheres and falling off at larger sizes. The nonlinear absorption coefficientsmore » for Au and Ag spheres are comparable in magnitude. On the other hand, the nonlinear absorption for Ag disks, when corrected for volume fraction, is several times higher. These trends in nonlinear absorption are correlated to local electric field enhancement through quasi-static mean-field theory. Through variable size aperture measurements, we also separate nonlinear scattering from nonlinear absorption. For all materials tested, we find that nonlinear scattering is highly directional and that its magnitude is comparable to that of nonlinear absorption. These results indicate methods to improve the efficacy of plasmonic nanoparticles as optical limiters in pulsed laser systems.« less