The Relationship Between Intensity Coding and Binaural Sensitivity in Adults With Cochlear Implants.

PubMed

Todd, Ann E; Goupell, Matthew J; Litovsky, Ruth Y

Many bilateral cochlear implant users show sensitivity to binaural information when stimulation is provided using a pair of synchronized electrodes. However, there is large variability in binaural sensitivity between and within participants across stimulation sites in the cochlea. It was hypothesized that within-participant variability in binaural sensitivity is in part affected by limitations and characteristics of the auditory periphery which may be reflected by monaural hearing performance. The objective of this study was to examine the relationship between monaural and binaural hearing performance within participants with bilateral cochlear implants. Binaural measures included dichotic signal detection and interaural time difference discrimination thresholds. Diotic signal detection thresholds were also measured. Monaural measures included dynamic range and amplitude modulation detection. In addition, loudness growth was compared between ears. Measures were made at three stimulation sites per listener. Greater binaural sensitivity was found with larger dynamic ranges. Poorer interaural time difference discrimination was found with larger difference between comfortable levels of the two ears. In addition, poorer diotic signal detection thresholds were found with larger differences between the dynamic ranges of the two ears. No relationship was found between amplitude modulation detection thresholds or symmetry of loudness growth and the binaural measures. The results suggest that some of the variability in binaural hearing performance within listeners across stimulation sites can be explained by factors nonspecific to binaural processing. The results are consistent with the idea that dynamic range and comfortable levels relate to peripheral neural survival and the width of the excitation pattern which could affect the fidelity with which central binaural nuclei process bilateral inputs.

Estimating indices of range shifts in birds using dynamic models when detection is imperfect

USGS Publications Warehouse

Clement, Matthew J.; Hines, James E.; Nichols, James D.; Pardieck, Keith L.; Ziolkowski, David J.

2016-01-01

There is intense interest in basic and applied ecology about the effect of global change on current and future species distributions. Projections based on widely used static modeling methods implicitly assume that species are in equilibrium with the environment and that detection during surveys is perfect. We used multiseason correlated detection occupancy models, which avoid these assumptions, to relate climate data to distributional shifts of Louisiana Waterthrush in the North American Breeding Bird Survey (BBS) data. We summarized these shifts with indices of range size and position and compared them to the same indices obtained using more basic modeling approaches. Detection rates during point counts in BBS surveys were low, and models that ignored imperfect detection severely underestimated the proportion of area occupied and slightly overestimated mean latitude. Static models indicated Louisiana Waterthrush distribution was most closely associated with moderate temperatures, while dynamic occupancy models indicated that initial occupancy was associated with diurnal temperature ranges and colonization of sites was associated with moderate precipitation. Overall, the proportion of area occupied and mean latitude changed little during the 1997–2013 study period. Near-term forecasts of species distribution generated by dynamic models were more similar to subsequently observed distributions than forecasts from static models. Occupancy models incorporating a finite mixture model on detection – a new extension to correlated detection occupancy models – were better supported and may reduce bias associated with detection heterogeneity. We argue that replacing phenomenological static models with more mechanistic dynamic models can improve projections of future species distributions. In turn, better projections can improve biodiversity forecasts, management decisions, and understanding of global change biology.

Opto-electronic pulsed THz systems

NASA Astrophysics Data System (ADS)

Planken, P. C. M.; van Rijmenam, C. E. W. M.; Schouten, R. N.

2005-07-01

We present an overview of pulsed THz emission and detection schemes and give results of a highly efficient, water-cooled, semi-large aperture THz emitter. Using electro-optic detection we obtain a dynamic range of more than 5000 in a total measurement time of 20 ms, which represents the highest dynamic range for THz emitters centred around femtosecond laser oscillators to date. We find that the detection sensitivity is completely determined by the photon shot-noise of the probe laser beam. As an application of our efficient THz emitter, we present the first measurement of a phonon resonance in a THz apertureless scanning near-field optical microscopy measurement.

The Relationship Between Intensity Coding and Binaural Sensitivity in Adults With Cochlear Implants

PubMed Central

Todd, Ann E.; Goupell, Matthew J.; Litovsky, Ruth Y.

2016-01-01

Objectives Many bilateral cochlear implant users show sensitivity to binaural information when stimulation is provided using a pair of synchronized electrodes. However, there is large variability in binaural sensitivity between and within participants across stimulation sites in the cochlea. It was hypothesized that within-participant variability in binaural sensitivity is in part affected by limitations and characteristics of the auditory periphery which may be reflected by monaural hearing performance. The objective of this study was to examine the relationship between monaural and binaural hearing performance within participants with bilateral cochlear implants. Design Binaural measures included dichotic signal detection and interaural time difference discrimination thresholds. Diotic signal detection thresholds were also measured. Monaural measures included dynamic range and amplitude modulation detection. In addition, loudness growth was compared between ears. Measures were made at three stimulation sites per listener. Results Greater binaural sensitivity was found with larger dynamic ranges. Poorer interaural time difference discrimination was found with larger difference between comfortable levels of the two ears. In addition, poorer diotic signal detection thresholds were found with larger differences between the dynamic ranges of the two ears. No relationship was found between amplitude modulation detection thresholds or symmetry of loudness growth and the binaural measures. Conclusions The results suggest that some of the variability in binaural hearing performance within listeners across stimulation sites can be explained by factors non-specific to binaural processing. The results are consistent with the idea that dynamic range and comfortable levels relate to peripheral neural survival and the width of the excitation pattern which could affect the fidelity with which central binaural nuclei process bilateral inputs. PMID:27787393

The effect of delay line on the performance of a fiber optic interferometric sensor

NASA Astrophysics Data System (ADS)

Lin, Yung-Li; Lin, Ken-Huang; Lin, Wuu-Wen; Chen, Mao-Hsiung

2007-09-01

The optical fiber has the features of low loss and wide bandwidth; it has replaced the coaxial cable as the mainstream of the communication system in recent years. Because of its high sensitivity characteristic, the interferometer is usually applied to long distance, weak signal detection. In general, if the area to be monitored is located far away, the weak signal will make it uneasy to detect. An interferometer is used for phase detection. Thus, the hydrophone which is based on interferometric fiber optic sensor has extremely high sensitivity. Sagnac interferometric hydrophone has low noise of marine environment, which is more suitably used to detect underwater acoustic signal than that of a Mach-Zehnder interferometer. In this paper, we propose the configuration of dual Sagnac interferometer, and use the mathematical methods to drive and design optimal two delay fiber lengths, which can enlarge the dynamic range of underwater acoustic detection. In addition, we also use software simulation to design optimal two delay fiber lengths. The experimental configuration of dual Sagnac interferometer with two optical delay line is shown as Fig. 1. The maximum and minimum measurable phase signal value of dual Sagnac interferometer (L II=2 km, L 4=222.2 m), shown in Fig. 3. The fiber optic sensor head is of mandrel type. The acoustic window is made of silicon rubbers. It was shown that we can increase their sensitivities by increasing number of wrapping fiber coils. In our experiment, the result shows that among all the mandrel sensor heads, the highest dynamic range is up to 37.6 +/- 1.4 dB, and its sensitivity is -223.3 +/-1.7 dB re V / 1μ Pa. As for the configuration of the optical interferometers, the intensity of the dual Sagnac interferometer is 20 dB larger than its Sagnac counterpart. Its dynamic range is above 66 dB where the frequency ranges is between 50 ~ 400 Hz, which is 24 dB larger than that of the Sagnac interferometer with the sensitivity of -192.0 dB re V / l μPa. In addition, by using software simulation to design optimal lengths of delay fibers, we can increase the dynamic range of interferometer on underwater acoustic detection. This paper verifies that, by means of adjusting the length of these two delay fibers, we can actually increase the dynamic range of acoustic signal detection.

Anti-dynamic-crosstalk method for single photon LIDAR detection

NASA Astrophysics Data System (ADS)

Zhang, Fan; Liu, Qiang; Gong, Mali; Fu, Xing

2017-11-01

With increasing number of vehicles equipped with light detection and ranging (LIDAR), crosstalk is identified as a critical and urgent issue in the range detection for active collision avoidance. Chaotic pulse position modulation (CPPM) applied in the transmitting pulse train has been shown to prevent crosstalk as well as range ambiguity. However, static and unified strategy on discrimination threshold and the number of accumulated pulse is not valid against crosstalk with varying number of sources and varying intensity of each source. This paper presents an adaptive algorithm to distinguish the target echo from crosstalk with dynamic and unknown level of intensity in the context of intelligent vehicles. New strategy is given based on receiver operating characteristics (ROC) curves that consider the detection requirements of the probability of detection and false alarm for the scenario with varying crosstalk. In the adaptive algorithm, the detected results are compared by the new strategy with both the number of accumulated pulses and the threshold being raised step by step, so that the target echo can be exactly identified from crosstalk with the dynamic and unknown level of intensity. The validity of the algorithm has been verified through the experiments with a single photon detector and the time correlated single photo counting (TCSPC) technique, demonstrating a marked drop in required shots for identifying the target compared with static and unified strategy

Quantification of disease marker in undiluted serum using an actuating layer-embedded microcantilever

NASA Astrophysics Data System (ADS)

Hwang, Kyo Seon; Jeon, Hye Kyung; Lee, Sang-Myung; Kim, Sang Kyung; Kim, Tae Song

2009-05-01

In this study, we describe the application feasibility of a dynamic microcantilever with regard to the detection of a specific protein in human serum or real blood using an end-point analysis. The mechanical response (i.e., resonant frequency) of a functionalized dynamic microcantilever was shown to be altered by molecular interactions, which allowed for the detection of biomolecules present in small quantities without any additional signal enhancements, such as labeling. For the application of the microcantilever sensors to bioassays of serum samples, the mechanical response from the nonspecific adsorption of abundant proteins must be reduced, because it significantly influences the output signal deviation of the microcantilever sensor. We implemented a label-free prostate specific antigen (PSA) detection protocol in standard serum via our established process, which was designed to minimize nonspecific protein adsorption. PSA is a tumor marker for prostate cancer, with a threshold concentration of 2-4 ng/ml (7.2-14.4 pM) for the distinction between patients and normal individuals. The dynamic range of our dynamic microcantilever-based PSA assay on the background of standard serum ranged between 0.1 and 100 ng/ml (3.6 and 3600 pM). It was suggested that the dynamic microcantilever might allow for the sensitive label-free detection of disease markers in an actual human sample.

Dual Transition Edge Sensor Bolometer for Enhanced Dynamic Range

NASA Technical Reports Server (NTRS)

Chervenak, J. A.; Benford, D. J.; Moseley, S. H.; Irwin, K. D.

2004-01-01

Broadband surveys at the millimeter and submillimeter wavelengths will require bolometers that can reach new limits of sensitivity and also operate under high background conditions. To address this need, we present results on a dual transition edge sensor (TES) device with two operating modes: one for low background, ultrasensitive detection and one for high background, enhanced dynamic range detection. The device consists of a detector element with two transition temperatures (T(sub c)) of 0.25 and 0.51 K located on the same micromachined, thermally isolated membrane structure. It can be biased on either transition, and features phonon-limited noise performance at the lower T(sub c). We measure noise performance on the lower transition 7 x 10(exp -18) W/rt(Hz) and the bias power on the upper transition of 12.5 pW, giving a factor of 10 enhancement of the dynamic range for the device. We discuss the biasable range of this type of device and present a design concept to optimize utility of the device.

Shack-Hartmann wavefront sensor with large dynamic range by adaptive spot search method.

PubMed

Shinto, Hironobu; Saita, Yusuke; Nomura, Takanori

2016-07-10

A Shack-Hartmann wavefront sensor (SHWFS) that consists of a microlens array and an image sensor has been used to measure the wavefront aberrations of human eyes. However, a conventional SHWFS has finite dynamic range depending on the diameter of the each microlens. The dynamic range cannot be easily expanded without a decrease of the spatial resolution. In this study, an adaptive spot search method to expand the dynamic range of an SHWFS is proposed. In the proposed method, spots are searched with the help of their approximate displacements measured with low spatial resolution and large dynamic range. By the proposed method, a wavefront can be correctly measured even if the spot is beyond the detection area. The adaptive spot search method is realized by using the special microlens array that generates both spots and discriminable patterns. The proposed method enables expanding the dynamic range of an SHWFS with a single shot and short processing time. The performance of the proposed method is compared with that of a conventional SHWFS by optical experiments. Furthermore, the dynamic range of the proposed method is quantitatively evaluated by numerical simulations.

Microfluidic flow rate detection based on integrated optical fiber cantilever.

PubMed

Lien, Victor; Vollmer, Frank

2007-10-01

We demonstrate an integrated microfluidic flow sensor with ultra-wide dynamic range, suitable for high throughput applications such as flow cytometry and particle sorting/counting. A fiber-tip cantilever transduces flow rates to optical signal readout, and we demonstrate a dynamic range from 0 to 1500 microL min(-1) for operation in water. Fiber-optic sensor alignment is guided by preformed microfluidic channels, and the dynamic range can be adjusted in a one-step chemical etch. An overall non-linear response is attributed to the far-field angular distribution of single-mode fiber output.

Local extinction and turnover rates at the edge and interior of species' ranges

USGS Publications Warehouse

Doherty, P.F.; Boulinier, T.; James., D.

2003-01-01

One hypothesis for the maintenance of the edge of a species' range suggests that more central (and abundant) populations are relatively stable and edge populations are less stable with increased local extinction and turnover rates. To date, estimates of such metrics are equivocal due to design and analysis flaws. Apparent increased estimates of extinction and turnover rates at the edge of range, versus the interior, could be a function of decreased detection probabilities alone, and not of a biological process. We estimated extinction and turnover rates for species at the interiors and edges of their ranges using an approach which incorporates potential heterogeneity in species detection probabilities. Extinction rates were higher at the edges (0.17 ?? 0.03 []) than in the interiors (0.04 ?? 0.01), as was turnover. Without taking the probability of detection into account these differences would be artificially magnified. Knowledge of extinction and turnover rates is essential in furthering our understanding of range dynamics, and in directing conservation efforts. This study further illustrates the practical application of methods proposed recently for estimating extinction rates and other community dynamic parameters.

Local extinction and turnover rates at the edge and interior of species' ranges

USGS Publications Warehouse

Doherty, P.F.; Boulinier, T.; Nichols, J.D.

2003-01-01

One hypothesis for the maintenance of the edge of a species' range suggests that more central (and abundant) populations are relatively stable and edge populations are less stable with increased local extinction and turnover rates. To date, estimates of such metrics are equivocal due to design and analysis flaws. Apparent increased estimates of extinction and turnover rates at the edge of range, versus the interior, could be a function of decreased detection probabilities alone, and not of a biological process. We estimated extinction and turnover rates for species at the interiors and edges of their ranges using an approach which incorporates potential heterogeneity in species detection probabilities. Extinction rates were higher at the edges (0.17 ' 0.03 [SE]) than in the interiors (0.04 ' 0.01), as was turnover. Without taking the probability of detection into account these differences would be artificially magnified. Knowledge of extinction and turnover rates is essential in furthering our understanding of range dynamics, and in directing conservation efforts. This study further illustrates the practical application of methods proposed recently for estimating extinction rates and other community dynamic parameters.

Dynamical complexity changes during two forms of meditation

NASA Astrophysics Data System (ADS)

Li, Jin; Hu, Jing; Zhang, Yinhong; Zhang, Xiaofeng

2011-06-01

Detection of dynamical complexity changes in natural and man-made systems has deep scientific and practical meaning. We use the base-scale entropy method to analyze dynamical complexity changes for heart rate variability (HRV) series during specific traditional forms of Chinese Chi and Kundalini Yoga meditation techniques in healthy young adults. The results show that dynamical complexity decreases in meditation states for two forms of meditation. Meanwhile, we detected changes in probability distribution of m-words during meditation and explained this changes using probability distribution of sine function. The base-scale entropy method may be used on a wider range of physiologic signals.

Doppler imaging with dual-detection full-range frequency domain optical coherence tomography

PubMed Central

Meemon, Panomsak; Lee, Kye-Sung; Rolland, Jannick P.

2010-01-01

Most of full-range techniques for Frequency Domain Optical Coherence Tomography (FD-OCT) reported to date utilize the phase relation between consecutive axial lines to reconstruct a complex interference signal and hence may exhibit degradation in either mirror image suppression performance or detectable velocity dynamic range or both when monitoring a moving sample such as flow activity. We have previously reported a technique of mirror image removal by simultaneous detection of the quadrature components of a complex spectral interference called a Dual-Detection Frequency Domain OCT (DD-FD-OCT) [Opt. Lett. 35, 1058-1060 (2010)]. The technique enables full range imaging without any loss of acquisition speed and is intrinsically less sensitive to phase errors generated by involuntary movements of the subject. In this paper, we demonstrate the application of the DD-FD-OCT to a phase-resolved Doppler imaging without degradation in either mirror image suppression performance or detectable velocity dynamic range that were observed in other full-range Doppler methods. In order to accommodate for Doppler imaging, we have developed a fiber-based DD-FD-OCT that more efficiently utilizes the source power compared with the previous free-space DD-FD-OCT. In addition, the velocity sensitivity of the phase-resolved DD-FD-OCT was investigated, and the relation between the measured Doppler phase shift and set flow velocity of a flow phantom was verified. Finally, we demonstrate the Doppler imaging using the DD-FD-OCT in a biological sample. PMID:21258488

Improved pulse shape discriminator for fast neutron-gamma ray detection system

NASA Technical Reports Server (NTRS)

Lockwood, J. A.; St. Onge, R.

1969-01-01

Discriminator in nuclear particle detection system distinguishes nuclear particle type and energy among many different nuclear particles. Discriminator incorporates passive, linear circuit elements so that it will operate over a wide dynamic range.

Detecting transitions in protein dynamics using a recurrence quantification analysis based bootstrap method.

PubMed

Karain, Wael I

2017-11-28

Proteins undergo conformational transitions over different time scales. These transitions are closely intertwined with the protein's function. Numerous standard techniques such as principal component analysis are used to detect these transitions in molecular dynamics simulations. In this work, we add a new method that has the ability to detect transitions in dynamics based on the recurrences in the dynamical system. It combines bootstrapping and recurrence quantification analysis. We start from the assumption that a protein has a "baseline" recurrence structure over a given period of time. Any statistically significant deviation from this recurrence structure, as inferred from complexity measures provided by recurrence quantification analysis, is considered a transition in the dynamics of the protein. We apply this technique to a 132 ns long molecular dynamics simulation of the β-Lactamase Inhibitory Protein BLIP. We are able to detect conformational transitions in the nanosecond range in the recurrence dynamics of the BLIP protein during the simulation. The results compare favorably to those extracted using the principal component analysis technique. The recurrence quantification analysis based bootstrap technique is able to detect transitions between different dynamics states for a protein over different time scales. It is not limited to linear dynamics regimes, and can be generalized to any time scale. It also has the potential to be used to cluster frames in molecular dynamics trajectories according to the nature of their recurrence dynamics. One shortcoming for this method is the need to have large enough time windows to insure good statistical quality for the recurrence complexity measures needed to detect the transitions.

Large dynamic range optical vector analyzer based on optical single-sideband modulation and Hilbert transform

NASA Astrophysics Data System (ADS)

Xue, Min; Pan, Shilong; Zhao, Yongjiu

2016-07-01

A large dynamic range optical vector analyzer (OVA) based on optical single-sideband modulation is proposed and demonstrated. By dividing the optical signal after optical device under test into two paths, reversing the phase of one swept sideband using a Hilbert transformer in one path, and detecting the two signals from the two paths with a balanced photodetector, the measurement errors induced by the residual -1st-order sideband and the high-order sidebands can be eliminated and the dynamic range of the measurement is increased. In a proof-of-concept experiment, the stimulated Brillouin scattering and a fiber Bragg grating are measured by OVAs with and without the Hilbert transform and balanced photodetection. Results show that about 40-dB improvement in the measurement dynamic range is realized by the proposed OVA.

A CMOS image sensor with programmable pixel-level analog processing.

PubMed

Massari, Nicola; Gottardi, Massimo; Gonzo, Lorenzo; Stoppa, David; Simoni, Andrea

2005-11-01

A prototype of a 34 x 34 pixel image sensor, implementing real-time analog image processing, is presented. Edge detection, motion detection, image amplification, and dynamic-range boosting are executed at pixel level by means of a highly interconnected pixel architecture based on the absolute value of the difference among neighbor pixels. The analog operations are performed over a kernel of 3 x 3 pixels. The square pixel, consisting of 30 transistors, has a pitch of 35 microm with a fill-factor of 20%. The chip was fabricated in a 0.35 microm CMOS technology, and its power consumption is 6 mW with 3.3 V power supply. The device was fully characterized and achieves a dynamic range of 50 dB with a light power density of 150 nW/mm2 and a frame rate of 30 frame/s. The measured fixed pattern noise corresponds to 1.1% of the saturation level. The sensor's dynamic range can be extended up to 96 dB using the double-sampling technique.

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

Gundlach-Graham, Alexander W.; Dennis, Elise; Ray, Steven J.

Here we describe the first combination of a Distance-of-Flight Mass Spectrometry (DOFMS) instrument and an inductively coupled plasma (ICP) ion source. DOFMS is a velocity-based MS technique in which ions of a range of mass-to-charge (m/z) values are detected simultaneously along the length of a spatially selective detector. As a relative of time-of-flight (TOF) MS, DOFMS leverages benefits fromboth TOFMS and spatially dispersive MS. The simultaneous detection of groups of m/z values improves dynamic range by spreading ion signal across many detector elements and reduces correlated noise by signal ratioing. To ascertain the performance characteristics of the ICP-DOFMS instrument, wemore » have employed a microchannel-plate/phosphor detection assembly with a scientific CCD to capture images of the phosphor plate. With this simple (and commercially available) detection scheme, elemental detection limits from 2–30 ng L*1 and a linear dynamic range of 5 orders of magnitude (10–106 ng L1) have been demonstrated. Additionally, a competitive isotope-ratio precision of 0.1% RSD has been achieved with only a 6 s signal integration period. In addition to first figures of merit, this paper outlines technical considerations for the design of the ICP-DOFMS.« less

Study of Static Microchannel Plate Saturation Effects for the Fast Plasma Investigation Dual Electron Spectrometers on NASA's Magnetospheric MultiScale Mission

NASA Technical Reports Server (NTRS)

Avanov, L. A.; Gliese, U.; Pollock, C. J.; Moore, T. E.; Chornay, D. J.; Barrie, A. C.; Kujawski, J. T.; Gershman, D. J.; Tucker, C. J.; Mariano, A.;

Large dynamic range terahertz spectrometers based on plasmonic photomixers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Wang, Ning; Javadi, Hamid; Jarrahi, Mona

2017-02-01

Heterodyne terahertz spectrometers are highly in demand for space explorations and astrophysics studies. A conventional heterodyne terahertz spectrometer consists of a terahertz mixer that mixes a received terahertz signal with a local oscillator signal to generate an intermediate frequency signal in the radio frequency (RF) range, where it can be easily processed and detected by RF electronics. Schottky diode mixers, superconductor-insulator-superconductor (SIS) mixers and hot electron bolometer (HEB) mixers are the most commonly used mixers in conventional heterodyne terahertz spectrometers. While conventional heterodyne terahertz spectrometers offer high spectral resolution and high detection sensitivity levels at cryogenic temperatures, their dynamic range and bandwidth are limited by the low radiation power of existing terahertz local oscillators and narrow bandwidth of existing terahertz mixers. To address these limitations, we present a novel approach for heterodyne terahertz spectrometry based on plasmonic photomixing. The presented design replaces terahertz mixer and local oscillator of conventional heterodyne terahertz spectrometers with a plasmonic photomixer pumped by an optical local oscillator. The optical local oscillator consists of two wavelength-tunable continuous-wave optical sources with a terahertz frequency difference. As a result, the spectrometry bandwidth and dynamic range of the presented heterodyne spectrometer is not limited by radiation frequency and power restrictions of conventional terahertz sources. We demonstrate a proof-of-concept terahertz spectrometer with more than 90 dB dynamic range and 1 THz spectrometry bandwidth.

Dynamic contrast-enhanced MRA at 1.5 T for detection of arteriovenous shunting before and after Onyx embolization of cerebral arteriovenous malformations.

PubMed

Nogueira, Raul G; Bayrlee, Ahmad; Hirsch, Joshua A; Yoo, Albert J; Copen, William A

2013-10-01

Conventional non-invasive angiographic techniques for evaluating cerebral Arteriovenous Malformations (cAVMs) after embolization treatment are limited by their inability to acquire time-resolved images. We describe the use of dynamic contrast-enhanced magnetic resonance angiography (MRA) in the evaluation of residual arteriovenous shunting in cAVMs following Onyx embolization. Six subjects who underwent multimodal MR imaging including dynamic MRA after different stages of endovascular treatment with Onyx were included. Each MRA was assessed for the presence of residual arteriovenous shunting. The results were compared with digital subtraction angiography (DSA). Mean age was 41 years (range, 25-63) and the mean maximum AVM diameter was 5.3 cm (range, 4.7-6.0). Fourteen dynamic MRA were performed using a 1.5 T scanner. Arteriovenous shunting was detected in thirteen of fourteen patients by both dynamic MRA and DSA, with complete agreement between the two techniques. The only MRA without detectable residual arteriovenous shunting was for a subject who had complete treatment with no residual cAVM as confirmed by the DSA images. Dynamic contrast-enhanced MRA is a promising non-invasive modality in identifying residual arteriovenous shunting after different stages of AVM embolization, achieving 100% agreement in this small study. Embolization with Onyx caused no significant image artifact. Copyright © 2013 by the American Society of Neuroimaging.

Trifunctional molecular beacon-mediated quadratic amplification for highly sensitive and rapid detection of mercury(II) ion with tunable dynamic range.

PubMed

Zhao, Yue; Liu, Huaqing; Chen, Feng; Bai, Min; Zhao, Junwu; Zhao, Yongxi

2016-12-15

Analyses of target with low abundance or concentration varying over many orders of magnitude are severe challenges faced by numerous assay methods due to their modest sensitivity and limited dynamic range. Here, we introduce a homogeneous and rapid quadratic polynomial amplification strategy through rational design of a trifunctional molecular beacon, which serves as not only a reporter molecule but also a bridge to couple two stage amplification modules without adding any reaction components or process other than basic linear amplification. As a test bed for our studies, we took mercury(II) ion as an example and obtained a high sensitivity with detection limit down to 200 pM within 30min. In order to create a tunable dynamic range, homotropic allostery is employed to modulate the target specific binding. When the number of metal binding site varies from 1 to 3, signal response is programmed accordingly with useful dynamic range spanning 50, 25 and 10 folds, respectively. Furthermore, the applicability of the proposed method in river water and biological samples are successfully verified with good recovery and reproducibility, indicating considerable potential for its practicality in complex real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Oligonucleotide-functionalized gold nanoparticles-enhanced QCM-D sensor for mercury(II) ions with high sensitivity and tunable dynamic range.

PubMed

Chen, Qiang; Wu, Xiaojie; Wang, Dingzhong; Tang, Wei; Li, Na; Liu, Feng

2011-06-21

A quartz crystal microbalance with dissipation monitoring (QCM-D) sensor was developed for highly sensitive and specific detection of mercury(II) ions (Hg(2+)) with a tunable dynamic range, using oligonucleotide-functionalized gold nanoparticles (GNPs) for both frequency and dissipation amplification. The fabrication of the sensor employed a 'sandwich-type' strategy, and formation of T-Hg(2+)-T structures in linker DNA reduced the hybridization of the GNPs-tagged DNA on the gold electrode, which could be used as the molecular switch for Hg(2+) sensing. This QCM-D mercury sensor showed a linear response of 10-200 nM, with detection limits of 4 nM and 7 nM for frequency and dissipation measurements, respectively. Moreover, the dynamic range of the sensor could be tuned by simply altering the concentration of linker DNA without designing new sensors in the cases where detection of Hg(2+) at different levels is required. This sensor afforded excellent selectivity toward Hg(2+) compared with other potential coexisting metal ions. The feasibility of the sensor was demonstrated by analyzing Hg(2+)-spiked tap- and lake-water samples with satisfactory recoveries. The proposed approach extended the application of the QCM-D system in metal ions sensing, and could be adopted for the detection of other analytes when complemented with the use of functional DNA structures.

An ultra-small, multi-point, and multi-color photo-detection system with high sensitivity and high dynamic range.

PubMed

Anazawa, Takashi; Yamazaki, Motohiro

2017-12-05

Although multi-point, multi-color fluorescence-detection systems are widely used in various sciences, they would find wider applications if they are miniaturized. Accordingly, an ultra-small, four-emission-point and four-color fluorescence-detection system was developed. Its size (space between emission points and a detection plane) is 15 × 10 × 12 mm, which is three-orders-of-magnitude smaller than that of a conventional system. Fluorescence from four emission points with an interval of 1 mm on the same plane was respectively collimated by four lenses and split into four color fluxes by four dichroic mirrors. Then, a total of sixteen parallel color fluxes were directly input into an image sensor and simultaneously detected. The emission-point plane and the detection plane (the image-sensor surface) were parallel and separated by a distance of only 12 mm. The developed system was applied to four-capillary array electrophoresis and successfully achieved Sanger DNA sequencing. Moreover, compared with a conventional system, the developed system had equivalent high fluorescence-detection sensitivity (lower detection limit of 17 pM dROX) and 1.6-orders-of-magnitude higher dynamic range (4.3 orders of magnitude).

Digital Microarrays: Single-Molecule Readout with Interferometric Detection of Plasmonic Nanorod Labels.

PubMed

Sevenler, Derin; Daaboul, George G; Ekiz Kanik, Fulya; Ünlü, Neşe Lortlar; Ünlü, M Selim

2018-05-21

DNA and protein microarrays are a high-throughput technology that allow the simultaneous quantification of tens of thousands of different biomolecular species. The mediocre sensitivity and limited dynamic range of traditional fluorescence microarrays compared to other detection techniques have been the technology's Achilles' heel and prevented their adoption for many biomedical and clinical diagnostic applications. Previous work to enhance the sensitivity of microarray readout to the single-molecule ("digital") regime have either required signal amplifying chemistry or sacrificed throughput, nixing the platform's primary advantages. Here, we report the development of a digital microarray which extends both the sensitivity and dynamic range of microarrays by about 3 orders of magnitude. This technique uses functionalized gold nanorods as single-molecule labels and an interferometric scanner which can rapidly enumerate individual nanorods by imaging them with a 10× objective lens. This approach does not require any chemical signal enhancement such as silver deposition and scans arrays with a throughput similar to commercial fluorescence scanners. By combining single-nanoparticle enumeration and ensemble measurements of spots when the particles are very dense, this system achieves a dynamic range of about 6 orders of magnitude directly from a single scan. As a proof-of-concept digital protein microarray assay, we demonstrated detection of hepatitis B virus surface antigen in buffer with a limit of detection of 3.2 pg/mL. More broadly, the technique's simplicity and high-throughput nature make digital microarrays a flexible platform technology with a wide range of potential applications in biomedical research and clinical diagnostics.

Functional near-infrared spectroscopy at small source-detector distance by means of high dynamic-range fast-gated SPAD acquisitions: first in-vivo measurements

NASA Astrophysics Data System (ADS)

Di Sieno, L.; Contini, D.; Dalla Mora, A.; Torricelli, A.; Spinelli, L.; Cubeddu, R.; Tosi, A.; Boso, G.; Pifferi, A.

2013-06-01

In this article, we show experimental results of time-resolved optical spectroscopy performed with small distance between launching and detecting fibers. It was already demonstrated that depth discrimination is independent of source-detector separation and that measurements at small source detector distance provide better contrast and spatial resolution. The main disadvantage is represent by the huge increase in early photons (scarcely diffused by tissue) peak that can saturate the dynamic range of most detectors, hiding information carried by late photons. Thanks to a fast-gated Single- Photon Avalanche Diode (SPAD) module, we are able to reject the peak of early photons and to obtain high-dynamic range acquisitions. We exploit fast-gated SPAD module to perform for the first time functional near-infrared spectroscopy (fNIRS) at small source-detector distance for in vivo measurements and we demonstrate the possibility to detect non-invasively the dynamics of oxygenated and deoxygenated haemoglobin occurring in the motor cortex during a motor task. We also show the improvement in terms of signal amplitude and Signal-to-Noise Ratio (SNR) obtained exploiting fast-gated SPAD performances with respect to "non-gated" measurements.

Smart CMOS sensor for wideband laser threat detection

NASA Astrophysics Data System (ADS)

Schwarze, Craig R.; Sonkusale, Sameer

2015-09-01

The proliferation of lasers has led to their widespread use in applications ranging from short range standoff chemical detection to long range Lidar sensing and target designation operating across the UV to LWIR spectrum. Recent advances in high energy lasers have renewed the development of laser weapons systems. The ability to measure and assess laser source information is important to both identify a potential threat as well as determine safety and nominal hazard zone (NHZ). Laser detection sensors are required that provide high dynamic range, wide spectral coverage, pulsed and continuous wave detection, and large field of view. OPTRA, Inc. and Tufts have developed a custom ROIC smart pixel imaging sensor architecture and wavelength encoding optics for measurement of source wavelength, pulse length, pulse repetition frequency (PRF), irradiance, and angle of arrival. The smart architecture provides dual linear and logarithmic operating modes to provide 8+ orders of signal dynamic range and nanosecond pulse measurement capability that can be hybridized with the appropriate detector array to provide UV through LWIR laser sensing. Recent advances in sputtering techniques provide the capability for post-processing CMOS dies from the foundry and patterning PbS and PbSe photoconductors directly on the chip to create a single monolithic sensor array architecture for measuring sources operating from 0.26 - 5.0 microns, 1 mW/cm2 - 2 kW/cm2.

A survey of design methods for failure detection in dynamic systems

NASA Technical Reports Server (NTRS)

Willsky, A. S.

1975-01-01

A number of methods for detecting abrupt changes (such as failures) in stochastic dynamical systems are surveyed. The class of linear systems is concentrated on but the basic concepts, if not the detailed analyses, carry over to other classes of systems. The methods surveyed range from the design of specific failure-sensitive filters, to the use of statistical tests on filter innovations, to the development of jump process formulations. Tradeoffs in complexity versus performance are discussed.

Coupled range dynamics of brood parasites and their hosts responding to climate and vegetation changes.

PubMed

Péron, Guillaume; Altwegg, Res; Jamie, Gabriel A; Spottiswoode, Claire N

2016-09-01

As populations shift their ranges in response to global change, local species assemblages can change, setting the stage for new ecological interactions, community equilibria and evolutionary responses. Here, we focus on the range dynamics of four avian brood parasite species and their hosts in southern Africa, in a context of bush encroachment (increase in woody vegetation density in places previously occupied by savanna-grassland mosaics) favouring some species at the expense of others. We first tested whether hosts and parasites constrained each other's ability to expand or maintain their ranges. Secondly, we investigated whether range shifts represented an opportunity for new host-parasite and parasite-parasite interactions. We used multispecies dynamic occupancy models with interactions, fitted to citizen science data, to estimate the contribution of interspecific interactions to range shifts and to quantify the change in species co-occurrence probability over a 25-year period. Parasites were able to track their hosts' range shifts. We detected no deleterious effect of the parasites' presence on either the local population viability of host species or the hosts' ability to colonize newly suitable areas. In the recently diversified indigobird radiation (Vidua spp.), following bush encroachment, the new assemblages presented more potential opportunities for speciation via host switch, but also more potential for hybridization between extant lineages, also via host switch. Multispecies dynamic occupancy models with interactions brought new insights into the feedbacks between range shifts, biotic interactions and local demography: brood parasitism had little detected impact on extinction or colonization processes, but inversely the latter processes affected biotic interactions via the modification of co-occurrence patterns. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

Microsomal metabolism of calycosin, formononetin and drug-drug interactions by dynamic microdialysis sampling and HPLC-DAD-MS analysis.

PubMed

Wen, Xiao-Dong; Qi, Lian-Wen; Li, Bin; Li, Ping; Yi, Ling; Wang, Ya-Qiong; Liu, E-Hu; Yang, Xiao-Lin

2009-08-15

A dynamic microdialysis sampling method with liquid chromatography-diode array detection and time-of-flight mass spectrometry (LC-DAD-TOF/MS) analysis was developed to investigate rat microsomal metabolisms of calycosin and formononetin, and their drug-drug interactions. Two hydroxylated metabolites from calycosin, and three hydroxylated or 4'-O-demethylated derivatives from formononetin were detected and identified after co-incubation with microsomes. Calibration curves offered linear ranges of two orders of magnitude with r(2)>0.999 for calycosin, formononetin and daidzein. The quantitative LC method provides a range of 0.028-0.034microg/mL for limits of detection, overall precision less than 5% and accuracy less than 3% by RSD. Besides, calycosin and formononetin were found to produce the depressive effect on the CYP450 enzyme reaction, and inhibit phase I enzyme reaction of each other when they are concurrent. Dynamic microdialysis sampling with LC-DAD-TOF/MS analysis developed in this work is a powerful tool for in vitro metabolism studies of drugs and metabolic interactions.

Acoustical nanometre-scale vibrations of live cells detected by a near-field optical setup

NASA Astrophysics Data System (ADS)

Piga, Rosaria; Micheletto, Ruggero; Kawakami, Yoichi

2007-04-01

The Scanning Near-field Optical Microscope (SNOM) is able to detect tiny vertical movement on the cell membrane in the range of only 1 nanometer or less, about 3 orders of magnitude better than conventional optical microscopes. Here we show intriguing data of cell membrane nanometer-scale dynamics associated to different phenomena of the cell’s The Scanning Near-field Optical Microscope (SNOM) is able to detect tiny vertical movement on the cell membrane in the range of only 1 nanometer or less, about 3 orders of magnitude better than conventional optical microscopes. Here we show intriguing data of cell membrane nanometer-scale dynamics associated to different phenomena of the cell’s life, such as cell cycle and cell death, on rat pheochromocytoma line PC12. Working in culture medium with alive and unperturbed samples, we could detect nanometer-sized movements; Fourier components revealed a clear distinct behavior associated to regulation of neurite outgrowth and changes on morphology after necrotic stimulus.

A Novel Method for Proximity Detection of Moving Targets Using a Large-Scale Planar Capacitive Sensor System

PubMed Central

Ye, Yong; Deng, Jiahao; Shen, Sanmin; Hou, Zhuo; Liu, Yuting

2016-01-01

A novel method for proximity detection of moving targets (with high dielectric constants) using a large-scale (the size of each sensor is 31 cm × 19 cm) planar capacitive sensor system (PCSS) is proposed. The capacitive variation with distance is derived, and a pair of electrodes in a planar capacitive sensor unit (PCSU) with a spiral shape is found to have better performance on sensitivity distribution homogeneity and dynamic range than three other shapes (comb shape, rectangular shape, and circular shape). A driving excitation circuit with a Clapp oscillator is proposed, and a capacitance measuring circuit with sensitivity of 0.21 Vp−p/pF is designed. The results of static experiments and dynamic experiments demonstrate that the voltage curves of static experiments are similar to those of dynamic experiments; therefore, the static data can be used to simulate the dynamic curves. The dynamic range of proximity detection for three projectiles is up to 60 cm, and the results of the following static experiments show that the PCSU with four neighboring units has the highest sensitivity (the sensitivities of other units are at least 4% lower); when the attack angle decreases, the intensity of sensor signal increases. This proposed method leads to the design of a feasible moving target detector with simple structure and low cost, which can be applied in the interception system. PMID:27196905

Swept-source based, single-shot, multi-detectable velocity range Doppler optical coherence tomography

PubMed Central

Meemon, Panomsak; Rolland, Jannick P.

2010-01-01

Phase-Resolved Doppler Optical Coherence Tomography (PR-DOCT) allows visualization and characterization of the location, direction, velocity, and profile of flow activity embedded in a static sample structure. The detectable Velocity Dynamic Range (VDR) of each particular PR-DOCT system is governed by a detectable Doppler phase shift, a flow angle, and an acquisition time interval used to determine the Doppler phase shift. In general, the lower boundary of the detectable Doppler phase shift is limited by the phase stability of the system, while the upper boundary is limited by the π phase ambiguity. For a given range of detectable Doppler phase shift, shortening the acquisition duration will increase not only the maximum detectable velocity but unfortunately also the minimum detectable velocity, which may lead to the invisibility of a slow flow. In this paper, we present an alternative acquisition scheme for PR-DOCT that extends the lower limit of the velocity dynamic range, while maintaining the maximum detectable velocity, hence increasing the overall VDR of PR-DOCT system. The essence of the approach is to implement a technique of multi-scale measurement to simultaneously acquire multiple VDRs in a single measurement. We demonstrate an example of implementation of the technique in a dual VDR DOCT, where two Doppler maps having different detectable VDRs were simultaneously detected, processed, and displayed in real time. One was a fixed VDR DOCT capable of measuring axial velocity of up to 10.9 mm/s without phase unwrapping. The other was a variable VDR DOCT capable of adjusting its detectable VDR to reveal slow flow information down to 11.3 μm/s. The technique is shown to effectively extend the overall detectable VDR of the PR-DOCT system. Examples of real time Doppler imaging of an African frog tadpole are demonstrated using the dual-VDR DOCT system. PMID:21258521

Sample Introduction Using the Hildebrand Grid Nebulizer for Plasma Spectrometry

DTIC Science & Technology

1988-01-01

linear dynamic ranges, precision, and peak width were de- termined for elements in methanol and acetonitrile solutions. , (1)> The grid nebulizer was...FIA) with ICP-OES detection were evaluated. Detec- tion limits, linear dynamic ranges, precision, and peak width were de- termined for elements in...Concentration vs. Log Peak Area for Mn, 59 Cd, Zn, Au, Ni in Methanol (CMSC) 3-28 Log Concentration vs. Log Peak Area for Mn, 60 Cd, Au, Ni in

A survey of design methods for failure detection in dynamic systems

NASA Technical Reports Server (NTRS)

Willsky, A. S.

1975-01-01

A number of methods for the detection of abrupt changes (such as failures) in stochastic dynamical systems were surveyed. The class of linear systems were emphasized, but the basic concepts, if not the detailed analyses, carry over to other classes of systems. The methods surveyed range from the design of specific failure-sensitive filters, to the use of statistical tests on filter innovations, to the development of jump process formulations. Tradeoffs in complexity versus performance are discussed.

Analysis of biogenic amines using corona discharge ion mobility spectrometry.

PubMed

Hashemian, Z; Mardihallaj, A; Khayamian, T

2010-05-15

A new method based on corona discharge ion mobility spectrometry (CD-IMS) was developed for the analysis of biogenic amines including spermidine, spermine, putrescine, and cadaverine. The ion mobility spectra of the compounds were obtained with and without n-Nonylamine used as the reagent gas. The high proton affinity of n-Nonylamine prevented ion formation from compounds with a proton affinity lower than that of n-Nonylamine and, therefore, enhanced its selectivity. It was also realized that the ion mobility spectrum of n-Nonylamine varied with its concentration. A sample injection port of a gas chromatograph was modified and used as the sample introduction system into the CD-IMS. The detection limits, dynamic ranges, and analytical parameters of the compounds with and without using the reagent gas were obtained. The detection limits and dynamic ranges of the compounds were about 2ng and 2 orders of magnitude, respectively. The wide dynamic range of CD-IMS originates from the high current of the corona discharge. The results revealed the high capability of the CD-IMS for the analysis of biogenic amines.

Detection of generalized synchronization using echo state networks

NASA Astrophysics Data System (ADS)

Ibáñez-Soria, D.; Garcia-Ojalvo, J.; Soria-Frisch, A.; Ruffini, G.

2018-03-01

Generalized synchronization between coupled dynamical systems is a phenomenon of relevance in applications that range from secure communications to physiological modelling. Here, we test the capabilities of reservoir computing and, in particular, echo state networks for the detection of generalized synchronization. A nonlinear dynamical system consisting of two coupled Rössler chaotic attractors is used to generate temporal series consisting of time-locked generalized synchronized sequences interleaved with unsynchronized ones. Correctly tuned, echo state networks are able to efficiently discriminate between unsynchronized and synchronized sequences even in the presence of relatively high levels of noise. Compared to other state-of-the-art techniques of synchronization detection, the online capabilities of the proposed Echo State Network based methodology make it a promising choice for real-time applications aiming to monitor dynamical synchronization changes in continuous signals.

Quantitation of secreted proteins using mCherry fusion constructs and a fluorescent microplate reader.

PubMed

Duellman, Tyler; Burnett, John; Yang, Jay

2015-03-15

Traditional assays for secreted proteins include methods such as Western blot and enzyme-linked immunosorbent assay (ELISA) detection of the protein in the cell culture medium. We describe a method for the detection of a secreted protein based on fluorescent measurement of an mCherry fusion reporter. This microplate reader-based mCherry fluorescence detection method has a wide dynamic range of 4.5 orders of magnitude and a sensitivity that allows detection of 1 to 2fmol fusion protein. Comparison with the Western blot detection method indicated greater linearity, wider dynamic range, and a similar lower detection threshold for the microplate-based fluorescent detection assay of secreted fusion proteins. An mCherry fusion protein of matrix metalloproteinase-9 (MMP-9), a secreted glycoprotein, was created and expressed by transfection of human embryonic kidney (HEK) 293 cells. The cell culture medium was assayed for the presence of the fluorescent signal up to 32 h after transfection. The secreted MMP-9-mCherry fusion protein was detected 6h after transfection with a linear increase in signal intensity over time. Treatment with chloroquine, a drug known to inhibit the secretion of many proteins, abolished the MMP-9-mCherry secretion, demonstrating the utility of this method in a biological experiment. Copyright © 2014 Elsevier Inc. All rights reserved.

Application of ultra-small-angle X-ray scattering / X-ray photon correlation spectroscopy to relate equilibrium or non-equilibrium dynamics to microstructure

NASA Astrophysics Data System (ADS)

Allen, Andrew; Zhang, Fan; Levine, Lyle; Ilavsky, Jan

2013-03-01

Ultra-small-angle X-ray scattering (USAXS) can probe microstructures over the nanometer-to-micrometer scale range. Through use of a small instrument entrance slit, X-ray photon correlation spectroscopy (XPCS) exploits the partial coherence of an X-ray synchrotron undulator beam to provide unprecedented sensitivity to the dynamics of microstructural change. In USAXS/XPCS studies, the dynamics of local structures in a scale range of 100 nm to 1000 nm can be related to an overall hierarchical microstructure extending from 1 nm to more than 1000 nm. Using a point-detection scintillator mode, the equilibrium dynamics at ambient temperature of small particles (which move more slowly than nanoparticles) in aqueous suspension have been quantified directly for the first time. Using a USAXS-XPCS scanning mode for non-equilibrium dynamics incipient processes within dental composites have been elucidated, prior to effects becoming detectable using any other technique. Use of the Advanced Photon Source, an Office of Science User Facility operated for the United States Department of Energy (U.S. DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357.

Detecting Intramolecular Conformational Dynamics of Single Molecules in Short Distance Range with Sub-Nanometer Sensitivity

PubMed Central

Zhou, Ruobo; Kunzelmann, Simone; Webb, Martin R.; Ha, Taekjip

2011-01-01

Single molecule detection is useful for characterizing nanoscale objects such as biological macromolecules, nano-particles and nano-devices with nano-meter spatial resolution. Fluorescence resonance energy transfer (FRET) is widely used as a single-molecule assay to monitor intramolecular dynamics in the distance range of 3–8 nm. Here we demonstrate that self-quenching of two rhodamine derivatives can be used to detect small conformational dynamics corresponding to sub-nanometer distance changes in a FRET-insensitive short range at the single molecule level. A ParM protein mutant labeled with two rhodamines works as a single molecule ADP sensor which has 20 times brighter fluorescence signal in the ADP bound state than the unbound state. Single molecule time trajectories show discrete transitions between fluorescence on and off states that can be directly ascribed to ADP binding and dissociation events. The conformational changes observed with 20:1 contrast are only 0.5 nm in magnitude and are between crystallographic distances of 1.6 nm and 2.1 nm, demonstrating exquisite sensitivity to short distance scale changes. The systems also allowed us to gain information on the photophysics of self-quenching induced by rhodamine stacking: (1) photobleaching of either of the two rhodamines eliminates quenching of the other rhodamine fluorophore and (2) photobleaching from the highly quenched, stacked state is only two-fold slower than from the unstacked state. PMID:22023515

Single-shot measurement of >1010 pulse contrast for ultra-high peak-power lasers

NASA Astrophysics Data System (ADS)

Wang, Yongzhi; Ma, Jingui; Wang, Jing; Yuan, Peng; Xie, Guoqiang; Ge, Xulei; Liu, Feng; Yuan, Xiaohui; Zhu, Heyuan; Qian, Liejia

2014-01-01

Real-time pulse-contrast observation with a high dynamic range is a prerequisite to tackle the contrast challenge in ultra-high peak-power lasers. However, the commonly used delay-scanning cross-correlator (DSCC) can only provide the time-consumed measurements for repetitive lasers. Single-shot cross-correlator (SSCC) becomes essential in optimizing laser systems and exploring contrast mechanisms. Here we report our progress in developing SSCC towards its practical use. By integrating both the techniques of scattering-noise reduction and sensitive parallel detection into SSCC, we demonstrate a high dynamic range of >1010, which, to our best knowledge, is the first demonstration of an SSCC with a dynamic range comparable to that of commercial DSCCs. The comparison of high-dynamic measurement performances between SSCC and a standard DSCC (Sequoia, Amplitude Technologies) is also carried out on a 200 TW Ti:sapphire laser, and the consistency of results verifies the veracity of our SSCC.

Highly-sensitive and large-dynamic diffuse optical tomography system for breast tumor detection

NASA Astrophysics Data System (ADS)

Du, Wenwen; Zhang, Limin; Yin, Guoyan; Zhang, Yanqi; Zhao, Huijuan; Gao, Feng

2018-02-01

Diffuse optical tomography (DOT) as a new functional imaging has important clinical applications in many aspects such as benign and malignant breast tumor detection, tumor staging and so on. For quantitative detection of breast tumor, a three-wavelength continuous-wave DOT prototype system combined the ultra-high sensitivity of the photon-counting detection and the measurement parallelism of the lock-in technique was developed to provide high temporal resolution, high sensitivity, large dynamic detection range and signal-to-noise ratio. Additionally, a CT-analogous scanning mode was proposed to cost-effectively increase the detection data. To evaluate the feasibility of the system, a series of assessments were conducted. The results demonstrate that the system can obtain high linearity, stability and negligible inter-wavelength crosstalk. The preliminary phantom experiments show the absorption coefficient is able to be successfully reconstructed, indicating that the system is one of the ideal platforms for optical breast tumor detection.

Preference limits of the visual dynamic range for ultra high quality and aesthetic conveyance

NASA Astrophysics Data System (ADS)

Daly, Scott; Kunkel, Timo; Sun, Xing; Farrell, Suzanne; Crum, Poppy

2013-03-01

A subjective study was conducted to investigate the preferred maximum and minimum display luminances in order to determine the dynamic ranges for future displays. Two studies address the diffuse reflective regions, and a third study tested preferences of highlight regions. Preferences, as opposed to detection thresholds, were studied to provide results more directly relevant to the viewing of entertainment or art. Test images were specifically designed to test these limits without the perceptual conflicts that usually occur in these types of studies. For the diffuse range, we found a display with a dynamic range having luminances between 0.1 and 650 cd/m2 matches the average preferences. However, to satisfy 90% of the population, a dynamic range from 0.005 and ~3,000 cd/m2 is needed. Since a display should be able to produce values brighter than the diffuse white maximum, as in specular highlights and emissive sources, the highlight study concludes that even the average preferred maximum luminance for highlight reproduction is ~4,000 cd/m2.

DNA nanomechanics allows direct digital detection of complementary DNA and microRNA targets.

PubMed

Husale, Sudhir; Persson, Henrik H J; Sahin, Ozgur

2009-12-24

Techniques to detect and quantify DNA and RNA molecules in biological samples have had a central role in genomics research. Over the past decade, several techniques have been developed to improve detection performance and reduce the cost of genetic analysis. In particular, significant advances in label-free methods have been reported. Yet detection of DNA molecules at concentrations below the femtomolar level requires amplified detection schemes. Here we report a unique nanomechanical response of hybridized DNA and RNA molecules that serves as an intrinsic molecular label. Nanomechanical measurements on a microarray surface have sufficient background signal rejection to allow direct detection and counting of hybridized molecules. The digital response of the sensor provides a large dynamic range that is critical for gene expression profiling. We have measured differential expressions of microRNAs in tumour samples; such measurements have been shown to help discriminate between the tissue origins of metastatic tumours. Two hundred picograms of total RNA is found to be sufficient for this analysis. In addition, the limit of detection in pure samples is found to be one attomolar. These results suggest that nanomechanical read-out of microarrays promises attomolar-level sensitivity and large dynamic range for the analysis of gene expression, while eliminating biochemical manipulations, amplification and labelling.

Digital PCR Modeling for Maximal Sensitivity, Dynamic Range and Measurement Precision

PubMed Central

Majumdar, Nivedita; Wessel, Thomas; Marks, Jeffrey

2015-01-01

The great promise of digital PCR is the potential for unparalleled precision enabling accurate measurements for genetic quantification. A challenge associated with digital PCR experiments, when testing unknown samples, is to perform experiments at dilutions allowing the detection of one or more targets of interest at a desired level of precision. While theory states that optimal precision (Po) is achieved by targeting ~1.59 mean copies per partition (λ), and that dynamic range (R) includes the space spanning one positive (λL) to one negative (λU) result from the total number of partitions (n), these results are tempered for the practitioner seeking to construct digital PCR experiments in the laboratory. A mathematical framework is presented elucidating the relationships between precision, dynamic range, number of partitions, interrogated volume, and sensitivity in digital PCR. The impact that false reaction calls and volumetric variation have on sensitivity and precision is next considered. The resultant effects on sensitivity and precision are established via Monte Carlo simulations reflecting the real-world likelihood of encountering such scenarios in the laboratory. The simulations provide insight to the practitioner on how to adapt experimental loading concentrations to counteract any one of these conditions. The framework is augmented with a method of extending the dynamic range of digital PCR, with and without increasing n, via the use of dilutions. An example experiment demonstrating the capabilities of the framework is presented enabling detection across 3.33 logs of starting copy concentration. PMID:25806524

Monoclonal Antibodies Attached to Carbon Nanotube Transistors for Paclitaxel Detection

NASA Astrophysics Data System (ADS)

Lee, Wonbae; Lau, Calvin; Richardson, Mark; Rajapakse, Arith; Weiss, Gregory; Collins, Philip; UCI, Molecular Biology; Biochemistry Collaboration; UCI, Departments of Physics; Astronomy Collaboration

Paclitaxel is a naturally-occurring pharmaceutical used in numerous cancer treatments, despite its toxic side effects. Partial inhibition of this toxicity has been demonstrated using weakly interacting monoclonal antibodies (3C6 and 8A10), but accurate monitoring of antibody and paclitaxel concentrations remains challenging. Here, single-molecule studies of the kinetics of antibody-paclitaxel interactions have been performed using single-walled carbon nanotube field-effect transistors. The devices were sensitized with single antibody attachments to record the single-molecule binding dynamics of paclitaxel. This label-free technique recorded a range of dynamic interactions between the antibody and paclitaxel, and it provided sensitive paclitaxel detection for pM to nM concentrations. Measurements with two different antibodies suggest ways of extending this working range and uncovering the mechanistic differences among different antibodies.

Detection and Tracking of Dynamic Objects by Using a Multirobot System: Application to Critical Infrastructures Surveillance

PubMed Central

Rodríguez-Canosa, Gonzalo; Giner, Jaime del Cerro; Barrientos, Antonio

2014-01-01

The detection and tracking of mobile objects (DATMO) is progressively gaining importance for security and surveillance applications. This article proposes a set of new algorithms and procedures for detecting and tracking mobile objects by robots that work collaboratively as part of a multirobot system. These surveillance algorithms are conceived of to work with data provided by long distance range sensors and are intended for highly reliable object detection in wide outdoor environments. Contrary to most common approaches, in which detection and tracking are done by an integrated procedure, the approach proposed here relies on a modular structure, in which detection and tracking are carried out independently, and the latter might accept input data from different detection algorithms. Two movement detection algorithms have been developed for the detection of dynamic objects by using both static and/or mobile robots. The solution to the overall problem is based on the use of a Kalman filter to predict the next state of each tracked object. Additionally, new tracking algorithms capable of combining dynamic objects lists coming from either one or various sources complete the solution. The complementary performance of the separated modular structure for detection and identification is evaluated and, finally, a selection of test examples discussed. PMID:24526305

A novel Laser Ion Mobility Spectrometer

NASA Astrophysics Data System (ADS)

Göbel, J.; Kessler, M.; Langmeier, A.

2009-05-01

IMS is a well know technology within the range of security based applications. Its main advantages lie in the simplicity of measurement, along with a fast and sensitive detection method. Contemporary technology often fails due to interference substances, in conjunction with saturation effects and a low dynamic detection range. High throughput facilities, such as airports, require the analysis of many samples at low detection limits within a very short timeframe. High detection reliability is a requirement for safe and secure operation. In our present work we developed a laser based ion-mobility-sensor which shows several advantages over known IMS sensor technology. The goal of our research was to increase the sensitivity compared to the range of 63Ni based instruments. This was achieved with an optimised geometric drift tube design and a pulsed UV laser system at an efficient intensity. In this intensity range multi-photon ionisation is possible, which leads to higher selectivity in the ion-formation process itself. After high speed capturing of detection samples, a custom designed pattern recognition software toolbox provides reliable auto-detection capability with a learning algorithm and a graphical user interface.

Multitarget, quantitative nanoplasmonic electrical field-enhanced resonating device (NE2RD) for diagnostics.

PubMed

Inci, Fatih; Filippini, Chiara; Baday, Murat; Ozen, Mehmet Ozgun; Calamak, Semih; Durmus, Naside Gozde; Wang, ShuQi; Hanhauser, Emily; Hobbs, Kristen S; Juillard, Franceline; Kuang, Ping Ping; Vetter, Michael L; Carocci, Margot; Yamamoto, Hidemi S; Takagi, Yuko; Yildiz, Umit Hakan; Akin, Demir; Wesemann, Duane R; Singhal, Amit; Yang, Priscilla L; Nibert, Max L; Fichorova, Raina N; Lau, Daryl T-Y; Henrich, Timothy J; Kaye, Kenneth M; Schachter, Steven C; Kuritzkes, Daniel R; Steinmetz, Lars M; Gambhir, Sanjiv S; Davis, Ronald W; Demirci, Utkan

2015-08-11

Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients' homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE(2)RD), which addresses all these impediments on a single platform. The NE(2)RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE(2)RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE(2)RD's broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the point-of-care or primary care settings and at patients' homes.

Multitarget, quantitative nanoplasmonic electrical field-enhanced resonating device (NE2RD) for diagnostics

PubMed Central

Inci, Fatih; Filippini, Chiara; Ozen, Mehmet Ozgun; Calamak, Semih; Durmus, Naside Gozde; Wang, ShuQi; Hanhauser, Emily; Hobbs, Kristen S.; Juillard, Franceline; Kuang, Ping Ping; Vetter, Michael L.; Carocci, Margot; Yamamoto, Hidemi S.; Takagi, Yuko; Yildiz, Umit Hakan; Akin, Demir; Wesemann, Duane R.; Singhal, Amit; Yang, Priscilla L.; Nibert, Max L.; Fichorova, Raina N.; Lau, Daryl T.-Y.; Henrich, Timothy J.; Kaye, Kenneth M.; Schachter, Steven C.; Kuritzkes, Daniel R.; Steinmetz, Lars M.; Gambhir, Sanjiv S.; Davis, Ronald W.; Demirci, Utkan

2015-01-01

Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients’ homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE2RD), which addresses all these impediments on a single platform. The NE2RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE2RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE2RD’s broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the point-of-care or primary care settings and at patients’ homes. PMID:26195743

Long-term fragmentation effects on the distribution and dynamics of canopy gaps in a tropical montane forest

Treesearch

Nicholas R. Vaughn; Gregory P. Asner; Christian P. Giardina

2015-01-01

Fragmentation alters forest canopy structure through various mechanisms, which in turn drive subsequent changes to biogeochemical processes and biological diversity. Using repeated airborne LiDAR (Light Detection and Ranging) mappings, we investigated the size distribution and dynamics of forest canopy gaps across a topical montane forest landscape in Hawaii naturally...

All-electrical detection of spin dynamics in magnetic antidot lattices by the inverse spin Hall effect

DOE PAGES

Jungfleisch, Matthias B.; Zhang, Wei; Ding, Junjia; ...

2016-02-03

The understanding of spin dynamics in laterally confined structures on sub-micron length scales has become a significant aspect of the development of novel magnetic storage technologies. Numerous ferromagnetic resonance measurements, optical characterization by Kerr microscopy and Brillouin light scattering spectroscopy and x-ray studies were carried out to detect the dynamics in patterned magnetic antidot lattices. Here, we investigate Oersted-field driven spin dynamics in rectangular Ni80Fe20/Pt antidot lattices with different lattice parameters by electrical means. When the system is driven to resonance, a dc voltage across the length of the sample is detected that changes its sign upon field reversal, whichmore » is in agreement with a rectification mechanism based on the inverse spin Hall effect. Furthermore, we show that the voltage output scales linearly with the applied microwave drive in the investigated range of powers. Lastly, our findings have direct implications on the development of engineered magnonics applications and devices.« less

Detection of coupling delay: A problem not yet solved

NASA Astrophysics Data System (ADS)

Coufal, David; Jakubík, Jozef; Jajcay, Nikola; Hlinka, Jaroslav; Krakovská, Anna; Paluš, Milan

2017-08-01

Nonparametric detection of coupling delay in unidirectionally and bidirectionally coupled nonlinear dynamical systems is examined. Both continuous and discrete-time systems are considered. Two methods of detection are assessed—the method based on conditional mutual information—the CMI method (also known as the transfer entropy method) and the method of convergent cross mapping—the CCM method. Computer simulations show that neither method is generally reliable in the detection of coupling delays. For continuous-time chaotic systems, the CMI method appears to be more sensitive and applicable in a broader range of coupling parameters than the CCM method. In the case of tested discrete-time dynamical systems, the CCM method has been found to be more sensitive, while the CMI method required much stronger coupling strength in order to bring correct results. However, when studied systems contain a strong oscillatory component in their dynamics, results of both methods become ambiguous. The presented study suggests that results of the tested algorithms should be interpreted with utmost care and the nonparametric detection of coupling delay, in general, is a problem not yet solved.

CE separation of proteins and yeasts dynamically modified by PEG pyrenebutanoate with fluorescence detection.

PubMed

Horká, Marie; Růzicka, Filip; Holá, Veronika; Slais, Karel

2007-07-01

The optimized protocols of the bioanalytes separation, proteins and yeasts, dynamically modified by the nonionogenic tenside PEG pyrenebutanoate, were applied in CZE and CIEF with the acidic gradient in pH range 2-5.5, both with fluorescence detection. PEG pyrenebutanoate was used as a buffer additive for a dynamic modification of proteins and/or yeast samples. The narrow peaks of modified analytes were detected. The values of the pI's of the labeled proteins were calculated using new fluorescent pI markers in CIEF and they were found to be comparable with pI's of the native compounds. As an example of the possible use of the suggested CIEF technique, the mixed cultures of yeasts, Candida albicans, Candida glabrata, Candida kefyr, Candida krusei, Candida lusitaniae, Candida parapsilosis, Candida tropicalis, Candida zeylanoides, Geotrichum candidum, Saccharomyces cerevisiae, Trichosporon asahii and Yarrowia lipolytica, were reproducibly focused and separated with high sensitivity. Using UV excitation for the on-column fluorometric detection, the minimum detectable amounts of analytes, femtograms of proteins and down to ten cells injected on the separation capillary, were estimated.

Au nanoparticle-based sensor for apomorphine detection in plasma

PubMed Central

Lucotti, Andrea; Tommasini, Matteo; Trusso, Sebastiano; de Grazia, Ugo; Ciusani, Emilio; Ossi, Paolo M

2015-01-01

Summary Artificially roughened gold surfaces with controlled nanostructure produced by pulsed laser deposition have been investigated as sensors for apomorphine detection aiming at clinical application. The use of such gold surfaces has been optimized using aqueous solutions of apomorphine in the concentration range between 3.3 × 10−4 M and 3.3 × 10−7 M. The experimental parameters have been investigated and the dynamic concentration range of the sensor has been assessed by the selection of two apomorphine surface enhanced Raman scattering (SERS) peaks. The sensor behavior used to detect apomorphine in unfiltered human blood plasma is presented and discussed. PMID:26734514

Efficient dynamic events discrimination technique for fiber distributed Brillouin sensors.

PubMed

Galindez, Carlos A; Madruga, Francisco J; Lopez-Higuera, Jose M

2011-09-26

A technique to detect real time variations of temperature or strain in Brillouin based distributed fiber sensors is proposed and is investigated in this paper. The technique is based on anomaly detection methods such as the RX-algorithm. Detection and isolation of dynamic events from the static ones are demonstrated by a proper processing of the Brillouin gain values obtained by using a standard BOTDA system. Results also suggest that better signal to noise ratio, dynamic range and spatial resolution can be obtained. For a pump pulse of 5 ns the spatial resolution is enhanced, (from 0.541 m obtained by direct gain measurement, to 0.418 m obtained with the technique here exposed) since the analysis is concentrated in the variation of the Brillouin gain and not only on the averaging of the signal along the time. © 2011 Optical Society of America

Neighborhood and habitat effects on vital rates: expansion of the Barred Owl in the Oregon Coast Ranges

Treesearch

Charles B. Yackulic; Janice Reid; Raymond Davis; James E. Hines; James D. Nichols; Eric Forsman

2012-01-01

In this paper, we modify dynamic occupancy models developed for detection-nondetection data to allow for the dependence of local vital rates on neighborhood occupancy, where neighborhood is defined very flexibly. Such dependence of occupancy dynamics on the status of a relevant neighborhood is pervasive, yet frequently ignored. Our framework permits joint inference...

Distance, flow and PCR inhibition: eDNA dynamics in two headwater streams

Treesearch

Stephen F. Jane; Taylor M. Wilcox; Kevin S. McKelvey; Michael K. Young; Michael K. Schwartz; Winsor H. Lowe; Benjamin H. Letcher; Andrew R. Whiteley

2014-01-01

Environmental DNA (eDNA) detection has emerged as a powerful tool for monitoring aquatic organisms, but much remains unknown about the dynamics of aquatic eDNA over a range of environmental conditions. DNA concentrations in streams and rivers will depend not only on the equilibrium between DNA entering the water and DNA leaving the system through degradation, but also...

Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources.

PubMed

Rutherford, Michael E; Chapman, David J; White, Thomas G; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E

2016-05-01

The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits).

Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

PubMed Central

Rutherford, Michael E.; Chapman, David J.; White, Thomas G.; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E.

2016-01-01

The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits). PMID:27140147

A new type of tri-axial accelerometers with high dynamic range MEMS for earthquake early warning

NASA Astrophysics Data System (ADS)

Peng, Chaoyong; Chen, Yang; Chen, Quansheng; Yang, Jiansi; Wang, Hongti; Zhu, Xiaoyi; Xu, Zhiqiang; Zheng, Yu

2017-03-01

Earthquake Early Warning System (EEWS) has shown its efficiency for earthquake damage mitigation. As the progress of low-cost Micro Electro Mechanical System (MEMS), many types of MEMS-based accelerometers have been developed and widely used in deploying large-scale, dense seismic networks for EEWS. However, the noise performance of these commercially available MEMS is still insufficient for weak seismic signals, leading to the large scatter of early-warning parameters estimation. In this study, we developed a new type of tri-axial accelerometer based on high dynamic range MEMS with low noise level using for EEWS. It is a MEMS-integrated data logger with built-in seismological processing. The device is built on a custom-tailored Linux 2.6.27 operating system and the method for automatic detecting seismic events is STA/LTA algorithms. When a seismic event is detected, peak ground parameters of all data components will be calculated at an interval of 1 s, and τc-Pd values will be evaluated using the initial 3 s of P wave. These values will then be organized as a trigger packet actively sent to the processing center for event combining detection. The output data of all three components are calibrated to sensitivity 500 counts/cm/s2. Several tests and a real field test deployment were performed to obtain the performances of this device. The results show that the dynamic range can reach 98 dB for the vertical component and 99 dB for the horizontal components, and majority of bias temperature coefficients are lower than 200 μg/°C. In addition, the results of event detection and real field deployment have shown its capabilities for EEWS and rapid intensity reporting.

Paper-based solid-phase multiplexed nucleic acid hybridization assay with tunable dynamic range using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Krull, Ulrich J

2013-08-06

A multiplexed solid-phase nucleic acid hybridization assay on a paper-based platform is presented using multicolor immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize two types of QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) and red-emitting QDs (rQDs) served as donors with Cy3 and Alexa Fluor 647 (A647) acceptors. The gQD/Cy3 FRET pair served as an internal standard, while the rQD/A647 FRET pair served as a detection channel, combining the control and analytical test zones in one physical location. Hybridization of dye-labeled oligonucleotide targets provided the proximity for FRET sensitized emission from the acceptor dyes, which served as an analytical signal. Hybridization assays in the multicolor format provided a limit of detection of 90 fmol and an upper limit of dynamic range of 3.5 pmol. The use of an array of detection zones was designed to provide improved analytical figures of merit compared to that which could be achieved on one type of array design in terms of relative concentration of multicolor QDs. The hybridization assays showed excellent resistance to nonspecific adsorption of oligonucleotides. Selectivity of the two-plex hybridization assay was demonstrated by single nucleotide polymorphism (SNP) detection at a contrast ratio of 50:1. Additionally, it is shown that the use of preformed QD-probe oligonucleotide conjugates and consideration of the relative number density of the two types of QD-probe conjugates in the two-color assay format is advantageous to maximize assay sensitivity and the upper limit of dynamic range.

Prototype of microbolometer thermal infrared camera for forest fire detection from space

NASA Astrophysics Data System (ADS)

Guerin, Francois; Dantes, Didier; Bouzou, Nathalie; Chorier, Philippe; Bouchardy, Anne-Marie; Rollin, Joël.

2017-11-01

The contribution of the thermal infrared (TIR) camera to the Earth observation FUEGO mission is to participate; to discriminate the clouds and smoke; to detect the false alarms of forest fires; to monitor the forest fires. Consequently, the camera needs a large dynamic range of detectable radiances. A small volume, low mass and power are required by the small FUEGO payload. These specifications can be attractive for other similar missions.

Characterization of resonant tunneling diodes for microwave and millimeter-wave detection

NASA Technical Reports Server (NTRS)

Mehdi, I.; East, J. R.; Haddad, G. I.

1991-01-01

The authors report on the direct detection capabilities of resonant tunneling diodes in the 10-100 GHz range. An open circuit voltage sensitivity of 1750 mV/mW (in Ka-band) was measured. This is higher than the sensitivity of comparatively based commercially available solid-state detectors. The detector properties are a strong function of diode bias and the measured tangential signal sensitivity (-32 dBm at Ka-band with 1-MHz bandwidth) and the dynamic range (25 dB) of the diode are smaller compared to other solid-state detectors.

Combining High Dynamic Range Photography and High Range Resolution RADAR for Pre-discharge Threat Cues

DTIC Science & Technology

2011-08-16

Munitions • Dragunov • AK47 • RPG • AR10 Confusers • Person with Tripod • Person with Broom Results • Dragunov, AK47 , RPG, and AR10 detected as...weapons • Person+Tripod declared as clutter • Person+Broom declared as clutter Notes • AK47 and Dragunov in same room Demo April 2010 Detection Results...tp9042 AK47 + Dragunov RPG Person + Tripod Person + Broom AR10 R an g e Sweep Number Sweep Number Declarations RADAR Data UNCLASSIFIED Summary

Single-shot measurement of >1010 pulse contrast for ultra-high peak-power lasers

PubMed Central

Wang, Yongzhi; Ma, Jingui; Wang, Jing; Yuan, Peng; Xie, Guoqiang; Ge, Xulei; Liu, Feng; Yuan, Xiaohui; Zhu, Heyuan; Qian, Liejia

2014-01-01

Real-time pulse-contrast observation with a high dynamic range is a prerequisite to tackle the contrast challenge in ultra-high peak-power lasers. However, the commonly used delay-scanning cross-correlator (DSCC) can only provide the time-consumed measurements for repetitive lasers. Single-shot cross-correlator (SSCC) becomes essential in optimizing laser systems and exploring contrast mechanisms. Here we report our progress in developing SSCC towards its practical use. By integrating both the techniques of scattering-noise reduction and sensitive parallel detection into SSCC, we demonstrate a high dynamic range of >1010, which, to our best knowledge, is the first demonstration of an SSCC with a dynamic range comparable to that of commercial DSCCs. The comparison of high-dynamic measurement performances between SSCC and a standard DSCC (Sequoia, Amplitude Technologies) is also carried out on a 200 TW Ti:sapphire laser, and the consistency of results verifies the veracity of our SSCC. PMID:24448655

Resonant and resistive dual-mode uncooled infrared detectors toward expanded dynamic range and high linearity

NASA Astrophysics Data System (ADS)

Li, Xin; Liang, Ji; Zhang, Hongxiang; Yang, Xing; Zhang, Hao; Pang, Wei; Zhang, Menglun

2017-06-01

This paper reports an uncooled infrared (IR) detector based on a micromachined piezoelectric resonator operating in resonant and resistive dual-modes. The two sensing modes achieved IR responsivities of 2.5 Hz/nW and 900 μdB/nW, respectively. Compared with the single mode operation, the dual-mode measurement improves the limit of detection by two orders of magnitude and meanwhile maintains high linearity and responsivity in a higher IR intensity range. A combination of the two sensing modes compensates for its own shortcomings and provides a much larger dynamic range, and thus, a wider application field of the proposed detector is realized.

Analytically Sensitive Protein Detection in Microtiter Plates by Proximity Ligation with Rolling Circle Amplification.

PubMed

Ebai, Tonge; Souza de Oliveira, Felipe Marques; Löf, Liza; Wik, Lotta; Schweiger, Caroline; Larsson, Anders; Keilholtz, Ulrich; Haybaeck, Johannes; Landegren, Ulf; Kamali-Moghaddam, Masood

2017-09-01

Detecting proteins at low concentrations in plasma is crucial for early diagnosis. Current techniques in clinical routine, such as sandwich ELISA, provide sensitive protein detection because of a dependence on target recognition by pairs of antibodies, but detection of still lower protein concentrations is often called for. Proximity ligation assay with rolling circle amplification (PLARCA) is a modified proximity ligation assay (PLA) for analytically specific and sensitive protein detection via binding of target proteins by 3 antibodies, and signal amplification via rolling circle amplification (RCA) in microtiter wells, easily adapted to instrumentation in use in hospitals. Proteins captured by immobilized antibodies were detected using a pair of oligonucleotide-conjugated antibodies. Upon target recognition these PLA probes guided oligonucleotide ligation, followed by amplification via RCA of circular DNA strands that formed in the reaction. The RCA products were detected by horseradish peroxidase-labeled oligonucleotides to generate colorimetric reaction products with readout in an absorbance microplate reader. We compared detection of interleukin (IL)-4, IL-6, IL-8, p53, and growth differentiation factor 15 (GDF-15) by PLARCA and conventional sandwich ELISA or immuno-RCA. PLARCA detected lower concentrations of proteins and exhibited a broader dynamic range compared to ELISA and iRCA using the same antibodies. IL-4 and IL-6 were detected in clinical samples at femtomolar concentrations, considerably lower than for ELISA. PLARCA offers detection of lower protein levels and increased dynamic ranges compared to ELISA. The PLARCA procedure may be adapted to routine instrumentation available in hospitals and research laboratories. © 2017 American Association for Clinical Chemistry.

A Bayesian state-space formulation of dynamic occupancy models

USGS Publications Warehouse

Royle, J. Andrew; Kery, M.

2007-01-01

Species occurrence and its dynamic components, extinction and colonization probabilities, are focal quantities in biogeography and metapopulation biology, and for species conservation assessments. It has been increasingly appreciated that these parameters must be estimated separately from detection probability to avoid the biases induced by nondetection error. Hence, there is now considerable theoretical and practical interest in dynamic occupancy models that contain explicit representations of metapopulation dynamics such as extinction, colonization, and turnover as well as growth rates. We describe a hierarchical parameterization of these models that is analogous to the state-space formulation of models in time series, where the model is represented by two components, one for the partially observable occupancy process and another for the observations conditional on that process. This parameterization naturally allows estimation of all parameters of the conventional approach to occupancy models, but in addition, yields great flexibility and extensibility, e.g., to modeling heterogeneity or latent structure in model parameters. We also highlight the important distinction between population and finite sample inference; the latter yields much more precise estimates for the particular sample at hand. Finite sample estimates can easily be obtained using the state-space representation of the model but are difficult to obtain under the conventional approach of likelihood-based estimation. We use R and Win BUGS to apply the model to two examples. In a standard analysis for the European Crossbill in a large Swiss monitoring program, we fit a model with year-specific parameters. Estimates of the dynamic parameters varied greatly among years, highlighting the irruptive population dynamics of that species. In the second example, we analyze route occupancy of Cerulean Warblers in the North American Breeding Bird Survey (BBS) using a model allowing for site-specific heterogeneity in model parameters. The results indicate relatively low turnover and a stable distribution of Cerulean Warblers which is in contrast to analyses of counts of individuals from the same survey that indicate important declines. This discrepancy illustrates the inertia in occupancy relative to actual abundance. Furthermore, the model reveals a declining patch survival probability, and increasing turnover, toward the edge of the range of the species, which is consistent with metapopulation perspectives on the genesis of range edges. Given detection/non-detection data, dynamic occupancy models as described here have considerable potential for the study of distributions and range dynamics.

Ultrasensitive microfluidic solid-phase ELISA using an actuatable microwell-patterned PDMS chip.

PubMed

Wang, Tanyu; Zhang, Mohan; Dreher, Dakota D; Zeng, Yong

2013-11-07

Quantitative detection of low abundance proteins is of significant interest for biological and clinical applications. Here we report an integrated microfluidic solid-phase ELISA platform for rapid and ultrasensitive detection of proteins with a wide dynamic range. Compared to the existing microfluidic devices that perform affinity capture and enzyme-based optical detection in a constant channel volume, the key novelty of our design is two-fold. First, our system integrates a microwell-patterned assay chamber that can be pneumatically actuated to significantly reduce the volume of chemifluorescent reaction, markedly improving the sensitivity and speed of ELISA. Second, monolithic integration of on-chip pumps and the actuatable assay chamber allow programmable fluid delivery and effective mixing for rapid and sensitive immunoassays. Ultrasensitive microfluidic ELISA was demonstrated for insulin-like growth factor 1 receptor (IGF-1R) across at least five orders of magnitude with an extremely low detection limit of 21.8 aM. The microwell-based solid-phase ELISA strategy provides an expandable platform for developing the next-generation microfluidic immunoassay systems that integrate and automate digital and analog measurements to further improve the sensitivity, dynamic ranges, and reproducibility of proteomic analysis.

Highly sensitive protein detection using a plasmonic field effect transistor (Conference Presentation)

NASA Astrophysics Data System (ADS)

Shokri-Kojori, Hossein; Ji, Yiwen; Han, Xu; Paik, Younghun; Braunschweig, Adam; Kim, Sung Jin

2016-03-01

Localized surface Plasmon Resonance (LSPR) is a nanoscale phenomenon which presents strong resonance associated with noble metal nanostructures. This plasmon resonance based technology enables highly sensitive detection for chemical and biological applications. Recently, we have developed a plasmon field effect transistor (FET) that enables direct plasmonic-to-electric signal conversion with signal amplification. The plasmon FET consists of back-gated field effect transistor incorporated with gold nanoparticles on top of the FET channel. The gold nanostructures are physically separated from transistor electrodes and can be functionalized for a specific biological application. In this presentation, we report a successful demonstration of a model system to detect Con A proteins using Carbohydrate linkers as a capture molecule. The plasmon FET detected a very low concentration of Con A (0.006 mg/L) while it offers a wide dynamic range of 0.006-50 mg/L. In this demonstration, we used two-color light sources instead of a bulky spectrometer to achieve high sensitivity and wide dynamic range. The details of two-color based differential measurement method will be discussed. This novel protein-based sensor has several advantages such as extremely small size for point-of-care system, multiplexing capability, no need of complex optical geometry.

Chemical and Biological Dynamics Using Droplet-Based Microfluidics.

PubMed

Dressler, Oliver J; Casadevall I Solvas, Xavier; deMello, Andrew J

2017-06-12

Recent years have witnessed an increased use of droplet-based microfluidic techniques in a wide variety of chemical and biological assays. Nevertheless, obtaining dynamic data from these platforms has remained challenging, as this often requires reading the same droplets (possibly thousands of them) multiple times over a wide range of intervals (from milliseconds to hours). In this review, we introduce the elemental techniques for the formation and manipulation of microfluidic droplets, together with the most recent developments in these areas. We then discuss a wide range of analytical methods that have been successfully adapted for analyte detection in droplets. Finally, we highlight a diversity of studies where droplet-based microfluidic strategies have enabled the characterization of dynamic systems that would otherwise have remained unexplorable.

Application of automatic gain control for radiometer diagnostic in SST-1 tokamak.

PubMed

Makwana, Foram R; Siju, Varsha; Edappala, Praveenlal; Pathak, S K

2017-12-01

This paper describes the characterisation of a negative feedback type of automatic gain control (AGC) circuit that will be an integral part of the heterodyne radiometer system operating at a frequency range of 75-86 GHz at SST-1 tokamak. The developed AGC circuit is a combination of variable gain amplifier and log amplifier which provides both gain and attenuation typically up to 15 dB and 45 dB, respectively, at a fixed set point voltage and it has been explored for the first time in tokamak radiometry application. The other important characteristics are that it exhibits a very fast response time of 390 ns to understand the fast dynamics of electron cyclotron emission and can operate at very wide input RF power dynamic range of around 60 dB that ensures signal level within the dynamic range of the detection system.

Satellite-tracking and Earth dynamics research programs

NASA Technical Reports Server (NTRS)

1982-01-01

The activities carried out by the Smithsonian Astrophysical Observatory (SAO) are described. The SAO network continued to track LAGEOS at highest priority for polar motion and Earth rotation studies, and for other geophysical investigations, including crustal dynamics, Earth and ocean tides, and the general development of precision orbit determination. The network performed regular tracking of several other retroreflector satellites including GEOS-1, GEOS-3, BE-C, and Starlette for refined determinations of station coordinates and the Earth's gravity field and for studies of solid Earth dynamics. A major program in laser upgrading continued to improve ranging accuracy and data yield. This program includes an increase in pulse repetition rate from 8 ppm to 30 ppm, a reduction in laser pulse width from 6 nsec to 2 to 3 nsec, improvements in the photoreceiver and the electronics to improve daylight ranging, and an analog pulse detection system to improve range noise and accuracy. Data processing hardware and software are discussed.

A high sensitive 66 dB linear dynamic range receiver for 3-D laser radar

NASA Astrophysics Data System (ADS)

Ma, Rui; Zheng, Hao; Zhu, Zhangming

2017-08-01

This study presents a CMOS receiver chip realized in 0.18 μm standard CMOS technology and intended for high precision 3-D laser radar. The chip includes an adjustable gain transimpedance pre-amplifier, a post-amplifier and two timing comparators. An additional feedback is employed in the regulated cascode transimpedance amplifier to decrease the input impedance, and a variable gain transimpedance amplifier controlled by digital switches and analog multiplexer is utilized to realize four gain modes, extending the input dynamic range. The measurement shows that the highest transimpedance of the channel is 50 k {{Ω }}, the uncompensated walk error is 1.44 ns in a wide linear dynamic range of 66 dB (1:2000), and the input referred noise current is 2.3 pA/\\sqrt{{Hz}} (rms), resulting in a very low detectable input current of 1 μA with SNR = 5.

Enhancing the Linear Dynamic Range in Multi-Channel Single Photon Detector beyond 7OD

PubMed Central

Gudkov, Dmytro; Gudkov, George; Gorbovitski, Boris; Gorfinkel, Vera

2015-01-01

We present design, implementation, and characterization of a single photon detector based on 32-channel PMT sensor [model H7260-20, Hamamatsu]. The developed high speed electronics enables the photon counting with linear dynamic range (LDR) up to 108count/s per detector's channel. The experimental characterization and Monte-Carlo simulations showed that in the single photon counting mode the LDR of the PMT sensor is limited by (i) “photon” pulse width (current pulse) of 900ps and (ii) substantial decrease of amplitudes of current pulses for count rates exceeding 108 count/s. The multi-channel architecture of the detector and the developed firm/software allow further expansion of the dynamic range of the device by 32-fold by using appropriate beam shaping. The developed single photon counting detector was tested for the detection of fluorescence labeled microbeads in capillary flow. PMID:27087788

Ultra-sensitive all-fibre photothermal spectroscopy with large dynamic range

PubMed Central

Jin, Wei; Cao, Yingchun; Yang, Fan; Ho, Hoi Lut

2015-01-01

Photothermal interferometry is an ultra-sensitive spectroscopic means for trace chemical detection in gas- and liquid-phase materials. Previous photothermal interferometry systems used free-space optics and have limitations in efficiency of light–matter interaction, size and optical alignment, and integration into photonic circuits. Here we exploit photothermal-induced phase change in a gas-filled hollow-core photonic bandgap fibre, and demonstrate an all-fibre acetylene gas sensor with a noise equivalent concentration of 2 p.p.b. (2.3 × 10−9 cm−1 in absorption coefficient) and an unprecedented dynamic range of nearly six orders of magnitude. The realization of photothermal interferometry with low-cost near infrared semiconductor lasers and fibre-based technology allows a class of optical sensors with compact size, ultra sensitivity and selectivity, applicability to harsh environment, and capability for remote and multiplexed multi-point detection and distributed sensing. PMID:25866015

Application of spin-exchange relaxation-free magnetometry to the Cosmic Axion Spin Precession Experiment

NASA Astrophysics Data System (ADS)

Wang, Tao; Kimball, Derek F. Jackson; Sushkov, Alexander O.; Aybas, Deniz; Blanchard, John W.; Centers, Gary; Kelley, Sean R. O.'; Wickenbrock, Arne; Fang, Jiancheng; Budker, Dmitry

2018-03-01

The Cosmic Axion Spin Precession Experiment (CASPEr) seeks to measure oscillating torques on nuclear spins caused by axion or axion-like-particle (ALP) dark matter via nuclear magnetic resonance (NMR) techniques. A sample spin-polarized along a leading magnetic field experiences a resonance when the Larmor frequency matches the axion/ALP Compton frequency, generating precessing transverse nuclear magnetization. Here we demonstrate a Spin-Exchange Relaxation-Free (SERF) magnetometer with sensitivity ≈ 1 fT /√{ Hz } and an effective sensing volume of 0.1 cm3 that may be useful for NMR detection in CASPEr. A potential drawback of SERF-magnetometer-based NMR detection is the SERF's limited dynamic range. Use of a magnetic flux transformer to suppress the leading magnetic field is considered as a potential method to expand the SERF's dynamic range in order to probe higher axion/ALP Compton frequencies.

A novel scattering switch-on detection technique for target-induced plasmon-coupling based sensing by single-particle optical anisotropy imaging.

PubMed

Peng, Lan; Cao, Xuan; Xiong, Bin; He, Yan; Yeung, Edward S

2016-06-18

We reported a novel scattering switch-on detection technique using flash-lamp polarization darkfield microscopy (FLPDM) for target-induced plasmon-coupling based sensing in homogeneous solution. With this method, we demonstrated sub-nM sensitivity for hydrogen sulfide (H2S) detection over a dynamic range of five orders of magnitude. This robust technique holds great promise for applications in toxic environmental pollutants and biological molecules.

Evaluation of the External RNA Controls Consortium (ERCC) reference material using a modified Latin square design.

PubMed

Pine, P Scott; Munro, Sarah A; Parsons, Jerod R; McDaniel, Jennifer; Lucas, Anne Bergstrom; Lozach, Jean; Myers, Timothy G; Su, Qin; Jacobs-Helber, Sarah M; Salit, Marc

2016-06-24

Highly multiplexed assays for quantitation of RNA transcripts are being used in many areas of biology and medicine. Using data generated by these transcriptomic assays requires measurement assurance with appropriate controls. Methods to prototype and evaluate multiple RNA controls were developed as part of the External RNA Controls Consortium (ERCC) assessment process. These approaches included a modified Latin square design to provide a broad dynamic range of relative abundance with known differences between four complex pools of ERCC RNA transcripts spiked into a human liver total RNA background. ERCC pools were analyzed on four different microarray platforms: Agilent 1- and 2-color, Illumina bead, and NIAID lab-made spotted microarrays; and two different second-generation sequencing platforms: the Life Technologies 5500xl and the Illumina HiSeq 2500. Individual ERCC controls were assessed for reproducible performance in signal response to concentration among the platforms. Most demonstrated linear behavior if they were not located near one of the extremes of the dynamic range. Performance issues with any individual ERCC transcript could be attributed to detection limitations, platform-specific target probe issues, or potential mixing errors. Collectively, these pools of spike-in RNA controls were evaluated for suitability as surrogates for endogenous transcripts to interrogate the performance of the RNA measurement process of each platform. The controls were useful for establishing the dynamic range of the assay, as well as delineating the useable region of that range where differential expression measurements, expressed as ratios, would be expected to be accurate. The modified Latin square design presented here uses a composite testing scheme for the evaluation of multiple performance characteristics: linear performance of individual controls, signal response within dynamic range pools of controls, and ratio detection between pairs of dynamic range pools. This compact design provides an economical sample format for the evaluation of multiple external RNA controls within a single experiment per platform. These results indicate that well-designed pools of RNA controls, spiked into samples, provide measurement assurance for endogenous gene expression studies.

A statistical model of false negative and false positive detection of phase singularities.

PubMed

Jacquemet, Vincent

2017-10-01

The complexity of cardiac fibrillation dynamics can be assessed by analyzing the distribution of phase singularities (PSs) observed using mapping systems. Interelectrode distance, however, limits the accuracy of PS detection. To investigate in a theoretical framework the PS false negative and false positive rates in relation to the characteristics of the mapping system and fibrillation dynamics, we propose a statistical model of phase maps with controllable number and locations of PSs. In this model, phase maps are generated from randomly distributed PSs with physiologically-plausible directions of rotation. Noise and distortion of the phase are added. PSs are detected using topological charge contour integrals on regular grids of varying resolutions. Over 100 × 10 6 realizations of the random field process are used to estimate average false negative and false positive rates using a Monte-Carlo approach. The false detection rates are shown to depend on the average distance between neighboring PSs expressed in units of interelectrode distance, following approximately a power law with exponents in the range of 1.14 to 2 for false negatives and around 2.8 for false positives. In the presence of noise or distortion of phase, false detection rates at high resolution tend to a non-zero noise-dependent lower bound. This model provides an easy-to-implement tool for benchmarking PS detection algorithms over a broad range of configurations with multiple PSs.

Comparison of two different solvents employed for pressurised fluid extraction of stevioside from Stevia rebaudiana: methanol versus water.

PubMed

Pól, Jaroslav; Varadová Ostrá, Elena; Karásek, Pavel; Roth, Michal; Benesová, Karolínka; Kotlaríková, Pavla; Cáslavský, Josef

2007-08-01

Pressurised fluid extraction using water or methanol was employed for the extraction of stevioside from Stevia rebaudiana Bertoni. The extraction method was optimised in terms of temperature and duration of the static or the dynamic step. Extracts were analysed by liquid chromatography followed by UV and mass-spectrometric (MS) detections. Thermal degradation of stevioside was the same in both solvents within the range 70-160 degrees C. Methanol showed better extraction ability for isolation of stevioside from Stevia rebaudiana leaves than water within the range 110-160 degrees C. However, water represents the green alternative to methanol. The limit of detection of stevioside in the extract analysed was 30 ng for UV detection and 2 ng for MS detection.

Highly sensitive, colorimetric detection of mercury(II) in aqueous media by quaternary ammonium group-capped gold nanoparticles at room temperature.

PubMed

Liu, Dingbin; Qu, Weisi; Chen, Wenwen; Zhang, Wei; Wang, Zhuo; Jiang, Xingyu

2010-12-01

We provide a highly sensitive and selective assay to detect Hg(2+) in aqueous solutions using gold nanoparticles modified with quaternary ammonium group-terminated thiols at room temperature. The mechanism is the abstraction of thiols by Hg(2+) that led to the aggregation of nanoparticles. With the assistance of solar light irradiation, the detection limit can be as low as 30 nM, which satisfies the guideline concentration of Hg(2+) in drinking water set by the WHO. In addition, the dynamic range of detection is wide (3 × 10(-8)-1 × 10(-2) M). This range, to our best knowledge, is the widest one that has been reported so far in gold nanoparticle (AuNP)-based assays for Hg(2+).

Analysis and design of a capsule landing system and surface vehicle control system for Mars exploration

NASA Technical Reports Server (NTRS)

Frederick, D. K.; Lashmet, P. K.; Sandor, G. N.; Shen, C. N.; Smith, E. V.; Yerazunis, S. W.

1973-01-01

Problems related to the design and control of a mobile planetary vehicle to implement a systematic plan for the exploration of Mars are reported. Problem areas include: vehicle configuration, control, dynamics, systems and propulsion; systems analysis, terrain modeling and path selection; and chemical analysis of specimens. These tasks are summarized: vehicle model design, mathematical model of vehicle dynamics, experimental vehicle dynamics, obstacle negotiation, electrochemical controls, remote control, collapsibility and deployment, construction of a wheel tester, wheel analysis, payload design, system design optimization, effect of design assumptions, accessory optimal design, on-board computer subsystem, laser range measurement, discrete obstacle detection, obstacle detection systems, terrain modeling, path selection system simulation and evaluation, gas chromatograph/mass spectrometer system concepts, and chromatograph model evaluation and improvement.

Ultrasensitive direct impedimetric immunosensor for detection of serum HER2.

PubMed

Sharma, Shikha; Zapatero-Rodríguez, Julia; Saxena, Rahul; O'Kennedy, Richard; Srivastava, Sudha

2018-05-30

Assesment of human epidermal growth factor receptor 2 status is a key factor prompting definitive treatment decisions that help in reducing mortality rates associated with breast cancer. In this article, highly sensitive and low-cost impedimetric immunosensor using single-chain fragment variable antibody fragments was developed for quantitative detection of human epidermal growth factor receptor 2 from serum employing gold nanoparticle-modified disposable screen-printed carbon electrodes. The gold nanoparticles facilitate fast electron transfer and offer a biocompatible surface for immobilization of small antibody fragments in an oriented manner, resulting in improved antigen binding efficiency. The single-chain fragment variable antibody fragment-modified screen printed immunosensor exhibits wide dynamic range of 0.01-100 ng mL -1 and detection limit of 0.01 ng mL -1 . The advantages offered by this platform in terms of high sensitivity, broad dynamic range and low-cost demonstrates great potential for improved monitoring of human epidermal growth factor receptor 2 levels for the management of breast and other cancers. Copyright © 2018 Elsevier B.V. All rights reserved.

Quantum sensing of weak radio-frequency signals by pulsed Mollow absorption spectroscopy.

PubMed

Joas, T; Waeber, A M; Braunbeck, G; Reinhard, F

2017-10-17

Quantum sensors-qubits sensitive to external fields-have become powerful detectors for various small acoustic and electromagnetic fields. A major key to their success have been dynamical decoupling protocols which enhance sensitivity to weak oscillating (AC) signals. Currently, those methods are limited to signal frequencies below a few MHz. Here we harness a quantum-optical effect, the Mollow triplet splitting of a strongly driven two-level system, to overcome this limitation. We microscopically understand this effect as a pulsed dynamical decoupling protocol and find that it enables sensitive detection of fields close to the driven transition. Employing a nitrogen-vacancy center, we detect GHz microwave fields with a signal strength (Rabi frequency) below the current detection limit, which is set by the center's spectral linewidth [Formula: see text]. Pushing detection sensitivity to the much lower 1/T 2 limit, this scheme could enable various applications, most prominently coherent coupling to single phonons and microwave photons.Dynamical decoupling protocols can enhance the sensitivity of quantum sensors but this is limited to signal frequencies below a few MHz. Here, Joas et al. use the Mollow triplet splitting in a nitrogen-vacancy centre to overcome this limitation, enabling sensitive detection of signals in the GHz range.

Time-resolved methods in biophysics. 7. Photon counting vs. analog time-resolved singlet oxygen phosphorescence detection.

PubMed

Jiménez-Banzo, Ana; Ragàs, Xavier; Kapusta, Peter; Nonell, Santi

2008-09-01

Two recent advances in optoelectronics, namely novel near-IR sensitive photomultipliers and inexpensive yet powerful diode-pumped solid-state lasers working at kHz repetition rate, enable the time-resolved detection of singlet oxygen (O2(a1Deltag)) phosphorescence in photon counting mode, thereby boosting the time-resolution, sensitivity, and dynamic range of this well-established detection technique. Principles underlying this novel approach and selected examples of applications are provided in this perspective, which illustrate the advantages over the conventional analog detection mode.

Fiber Bragg Grating Sensor System for Monitoring Smart Composite Aerospace Structures

NASA Technical Reports Server (NTRS)

Moslehi, Behzad; Black, Richard J.; Gowayed, Yasser

2012-01-01

Lightweight, electromagnetic interference (EMI) immune, fiber-optic, sensor- based structural health monitoring (SHM) will play an increasing role in aerospace structures ranging from aircraft wings to jet engine vanes. Fiber Bragg Grating (FBG) sensors for SHM include advanced signal processing, system and damage identification, and location and quantification algorithms. Potentially, the solution could be developed into an autonomous onboard system to inspect and perform non-destructive evaluation and SHM. A novel method has been developed to massively multiplex FBG sensors, supported by a parallel processing interrogator, which enables high sampling rates combined with highly distributed sensing (up to 96 sensors per system). The interrogation system comprises several subsystems. A broadband optical source subsystem (BOSS) and routing and interface module (RIM) send light from the interrogation system to a composite embedded FBG sensor matrix, which returns measurand-dependent wavelengths back to the interrogation system for measurement with subpicometer resolution. In particular, the returned wavelengths are channeled by the RIM to a photonic signal processing subsystem based on powerful optical chips, then passed through an optoelectronic interface to an analog post-detection electronics subsystem, digital post-detection electronics subsystem, and finally via a data interface to a computer. A range of composite structures has been fabricated with FBGs embedded. Stress tensile, bending, and dynamic strain tests were performed. The experimental work proved that the FBG sensors have a good level of accuracy in measuring the static response of the tested composite coupons (down to submicrostrain levels), the capability to detect and monitor dynamic loads, and the ability to detect defects in composites by a variety of methods including monitoring the decay time under different dynamic loading conditions. In addition to quasi-static and dynamic load monitoring, the system can capture acoustic emission events that can be a prelude to structural failure, as well as piezoactuator-induced ultrasonic Lamb-waves-based techniques as a basis for damage detection.

Computational and Mathematical Modeling of Coupled Superconducting Quantum Interference Devices

NASA Astrophysics Data System (ADS)

Berggren, Susan Anne Elizabeth

This research focuses on conducting an extensive computational investigation and mathematical analysis into the average voltage response of arrays of Superconducting Quantum Interference Devices (SQUIDs). These arrays will serve as the basis for the development of a sensitive, low noise, significantly lower Size, Weight and Power (SWaP) antenna integrated with Low-Noise Amplifier (LNA) using the SQUID technology. The goal for this antenna is to be capable of meeting all requirements for Guided Missile Destroyers (DDG) 1000 class ships for Information Operations/Signals Intelligence (IO/SIGINT) applications in Very High Frequency/Ultra High Frequency (V/UHF) bands. The device will increase the listening capability of receivers by moving technology into a new regime of energy detection allowing wider band, smaller size, more sensitive, stealthier systems. The smaller size and greater sensitivity will allow for ships to be “de-cluttered” of their current large dishes and devices, replacing everything with fewer and smaller SQUID antenna devices. The fewer devices present on the deck of a ship, the more invisible the ship will be to enemy forces. We invent new arrays of SQUIDs, optimized for signal detection with very high dynamic range and excellent spur-free dynamic range, while maintaining extreme small size (and low radar cross section), wide bandwidth, and environmentally noise limited sensitivity, effectively shifting the bottle neck of receiver systems forever away from the antenna itself deeper into the receiver chain. To accomplish these goals we develop and validate mathematical models for different designs of SQUID arrays and use them to invent a new device and systems design. This design is capable of significantly exceeding, per size weight and power, state-of-the-art receiver system measures of performance, such as bandwidth, sensitivity, dynamic range, and spurious-free dynamic range.

Wide-Field Imaging Using Nitrogen Vacancies

NASA Technical Reports Server (NTRS)

Englund, Dirk Robert (Inventor); Trusheim, Matthew Edwin (Inventor)

2017-01-01

Nitrogen vacancies in bulk diamonds and nanodiamonds can be used to sense temperature, pressure, electromagnetic fields, and pH. Unfortunately, conventional sensing techniques use gated detection and confocal imaging, limiting the measurement sensitivity and precluding wide-field imaging. Conversely, the present sensing techniques do not require gated detection or confocal imaging and can therefore be used to image temperature, pressure, electromagnetic fields, and pH over wide fields of view. In some cases, wide-field imaging supports spatial localization of the NVs to precisions at or below the diffraction limit. Moreover, the measurement range can extend over extremely wide dynamic range at very high sensitivity.

Eddy current gauge for monitoring displacement using printed circuit coil

DOEpatents

Visioli, Jr., Armando J.

1977-01-01

A proximity detection system for non-contact displacement and proximity measurement of static or dynamic metallic or conductive surfaces is provided wherein the measurement is obtained by monitoring the change in impedance of a flat, generally spiral-wound, printed circuit coil which is excited by a constant current, constant frequency source. The change in impedance, which is detected as a corresponding change in voltage across the coil, is related to the eddy current losses in the distant conductive material target. The arrangement provides for considerable linear displacement range with increased accuracies, stability, and sensitivity over the entire range.

Characterization of Combustion Dynamics, Detection, and Prevention of an Unstable Combustion State Based on a Complex-Network Theory

NASA Astrophysics Data System (ADS)

Gotoda, Hiroshi; Kinugawa, Hikaru; Tsujimoto, Ryosuke; Domen, Shohei; Okuno, Yuta

2017-04-01

Complex-network theory has attracted considerable attention for nearly a decade, and it enables us to encompass our understanding of nonlinear dynamics in complex systems in a wide range of fields, including applied physics and mechanical, chemical, and electrical engineering. We conduct an experimental study using a pragmatic online detection methodology based on complex-network theory to prevent a limiting unstable state such as blowout in a confined turbulent combustion system. This study introduces a modified version of the natural visibility algorithm based on the idea of a visibility limit to serve as a pragmatic online detector. The average degree of the modified version of the natural visibility graph allows us to detect the onset of blowout, resulting in online prevention.

A dynamic sandwich assay on magnetic beads for selective detection of single-nucleotide mutations at room temperature.

PubMed

Wang, Junxiu; Xiong, Guoliang; Ma, Liang; Wang, Shihui; Zhou, Xu; Wang, Lei; Xiao, Lehui; Su, Xin; Yu, Changyuan

2017-08-15

Single-nucleotide mutation (SNM) has proven to be associated with a variety of human diseases. Development of reliable methods for the detection of SNM is crucial for molecular diagnosis and personalized medicine. The sandwich assays are widely used tools for detecting nucleic acid biomarkers due to their low cost and rapid signaling. However, the poor hybridization specificity of signal probe at room temperature hampers the discrimination of mutant and wild type. Here, we demonstrate a dynamic sandwich assay on magnetic beads for SNM detection based on the transient binding between signal probe and target. By taking the advantage of mismatch sensitive thermodynamics of transient DNA binding, the dynamic sandwich assay exhibits high discrimination factor for mutant with a broad range of salt concentration at room temperature. The beads used in this assay serve as a tool for separation, and might be helpful to enhance SNM selectivity. Flexible design of signal probe and facile magnetic separation allow multiple-mode downstream analysis including colorimetric detection and isothermal amplification. With this method, BRAF mutations in the genomic DNA extracted from cancer cell lines were tested, allowing sensitive detection of SNM at very low abundances (0.1-0.5% mutant/wild type). Copyright © 2017 Elsevier B.V. All rights reserved.

Detection-dependent kinetics as a probe of folding landscape microstructure.

PubMed

Yang, Wei Yuan; Gruebele, Martin

2004-06-30

The folding landscapes of polypeptides and proteins exhibit a hierarchy of local minima. The causes range from proline isomerization all the way down to microstructure in the free energy caused by residual frustration inherent in even the best 20 amino acid design. The corresponding time scales range from hours to submicroseconds. The smallest microstructures are difficult to detect. We have measured the folding/unfolding kinetics of the engineered trpzip2 peptide at different tryptophan fluorescence wavelengths, each yielding a different rate. Wavelength-dependent folding kinetics on 0.1-2 mus time scales show that different microstructures with a range of solvent exposure and local dynamics are populated. We estimate a lower limit for the roughness of the free energy surface based on the range of rates observed.

Detection of time delays and directional interactions based on time series from complex dynamical systems

NASA Astrophysics Data System (ADS)

Ma, Huanfei; Leng, Siyang; Tao, Chenyang; Ying, Xiong; Kurths, Jürgen; Lai, Ying-Cheng; Lin, Wei

2017-07-01

Data-based and model-free accurate identification of intrinsic time delays and directional interactions is an extremely challenging problem in complex dynamical systems and their networks reconstruction. A model-free method with new scores is proposed to be generally capable of detecting single, multiple, and distributed time delays. The method is applicable not only to mutually interacting dynamical variables but also to self-interacting variables in a time-delayed feedback loop. Validation of the method is carried out using physical, biological, and ecological models and real data sets. Especially, applying the method to air pollution data and hospital admission records of cardiovascular diseases in Hong Kong reveals the major air pollutants as a cause of the diseases and, more importantly, it uncovers a hidden time delay (about 30-40 days) in the causal influence that previous studies failed to detect. The proposed method is expected to be universally applicable to ascertaining and quantifying subtle interactions (e.g., causation) in complex systems arising from a broad range of disciplines.

Dynamic programming in parallel boundary detection with application to ultrasound intima-media segmentation.

PubMed

Zhou, Yuan; Cheng, Xinyao; Xu, Xiangyang; Song, Enmin

2013-12-01

Segmentation of carotid artery intima-media in longitudinal ultrasound images for measuring its thickness to predict cardiovascular diseases can be simplified as detecting two nearly parallel boundaries within a certain distance range, when plaque with irregular shapes is not considered. In this paper, we improve the implementation of two dynamic programming (DP) based approaches to parallel boundary detection, dual dynamic programming (DDP) and piecewise linear dual dynamic programming (PL-DDP). Then, a novel DP based approach, dual line detection (DLD), which translates the original 2-D curve position to a 4-D parameter space representing two line segments in a local image segment, is proposed to solve the problem while maintaining efficiency and rotation invariance. To apply the DLD to ultrasound intima-media segmentation, it is imbedded in a framework that employs an edge map obtained from multiplication of the responses of two edge detectors with different scales and a coupled snake model that simultaneously deforms the two contours for maintaining parallelism. The experimental results on synthetic images and carotid arteries of clinical ultrasound images indicate improved performance of the proposed DLD compared to DDP and PL-DDP, with respect to accuracy and efficiency. Copyright © 2013 Elsevier B.V. All rights reserved.

Adaptive Impact-Driven Detection of Silent Data Corruption for HPC Applications

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

Di, Sheng; Cappello, Franck

For exascale HPC applications, silent data corruption (SDC) is one of the most dangerous problems because there is no indication that there are errors during the execution. We propose an adaptive impact-driven method that can detect SDCs dynamically. The key contributions are threefold. (1) We carefully characterize 18 real-world HPC applications and discuss the runtime data features, as well as the impact of the SDCs on their execution results. (2) We propose an impact-driven detection model that does not blindly improve the prediction accuracy, but instead detects only influential SDCs to guarantee user-acceptable execution results. (3) Our solution can adaptmore » to dynamic prediction errors based on local runtime data and can automatically tune detection ranges for guaranteeing low false alarms. Experiments show that our detector can detect 80-99.99% of SDCs with a false alarm rate less that 1% of iterations for most cases. The memory cost and detection overhead are reduced to 15% and 6.3%, respectively, for a large majority of applications.« less

Multiplexed quantification of nucleic acids with large dynamic range using multivolume digital RT-PCR on a rotational SlipChip tested with HIV and hepatitis C viral load.

PubMed

Shen, Feng; Sun, Bing; Kreutz, Jason E; Davydova, Elena K; Du, Wenbin; Reddy, Poluru L; Joseph, Loren J; Ismagilov, Rustem F

2011-11-09

In this paper, we are working toward a problem of great importance to global health: determination of viral HIV and hepatitis C (HCV) loads under point-of-care and resource limited settings. While antiretroviral treatments are becoming widely available, viral load must be evaluated at regular intervals to prevent the spread of drug resistance and requires a quantitative measurement of RNA concentration over a wide dynamic range (from 50 up to 10(6) molecules/mL for HIV and up to 10(8) molecules/mL for HCV). "Digital" single molecule measurements are attractive for quantification, but the dynamic range of such systems is typically limited or requires excessive numbers of compartments. Here we designed and tested two microfluidic rotational SlipChips to perform multivolume digital RT-PCR (MV digital RT-PCR) experiments with large and tunable dynamic range. These designs were characterized using synthetic control RNA and validated with HIV viral RNA and HCV control viral RNA. The first design contained 160 wells of each of four volumes (125 nL, 25 nL, 5 nL, and 1 nL) to achieve a dynamic range of 5.2 × 10(2) to 4.0 × 10(6) molecules/mL at 3-fold resolution. The second design tested the flexibility of this approach, and further expanded it to allow for multiplexing while maintaining a large dynamic range by adding additional wells with volumes of 0.2 nL and 625 nL and dividing the SlipChip into five regions to analyze five samples each at a dynamic range of 1.8 × 10(3) to 1.2 × 10(7) molecules/mL at 3-fold resolution. No evidence of cross-contamination was observed. The multiplexed SlipChip can be used to analyze a single sample at a dynamic range of 1.7 × 10(2) to 2.0 × 10(7) molecules/mL at 3-fold resolution with limit of detection of 40 molecules/mL. HIV viral RNA purified from clinical samples were tested on the SlipChip, and viral load results were self-consistent and in good agreement with results determined using the Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 Test. With further validation, this SlipChip should become useful to precisely quantify viral HIV and HCV RNA for high-performance diagnostics in resource-limited settings. These microfluidic designs should also be valuable for other diagnostic and research applications, including detecting rare cells and rare mutations, prenatal diagnostics, monitoring residual disease, and quantifying copy number variation and gene expression patterns. The theory for the design and analysis of multivolume digital PCR experiments is presented in other work by Kreutz et al.

Markov Dynamics as a Zooming Lens for Multiscale Community Detection: Non Clique-Like Communities and the Field-of-View Limit

PubMed Central

Schaub, Michael T.; Delvenne, Jean-Charles; Yaliraki, Sophia N.; Barahona, Mauricio

2012-01-01

In recent years, there has been a surge of interest in community detection algorithms for complex networks. A variety of computational heuristics, some with a long history, have been proposed for the identification of communities or, alternatively, of good graph partitions. In most cases, the algorithms maximize a particular objective function, thereby finding the ‘right’ split into communities. Although a thorough comparison of algorithms is still lacking, there has been an effort to design benchmarks, i.e., random graph models with known community structure against which algorithms can be evaluated. However, popular community detection methods and benchmarks normally assume an implicit notion of community based on clique-like subgraphs, a form of community structure that is not always characteristic of real networks. Specifically, networks that emerge from geometric constraints can have natural non clique-like substructures with large effective diameters, which can be interpreted as long-range communities. In this work, we show that long-range communities escape detection by popular methods, which are blinded by a restricted ‘field-of-view’ limit, an intrinsic upper scale on the communities they can detect. The field-of-view limit means that long-range communities tend to be overpartitioned. We show how by adopting a dynamical perspective towards community detection [1], [2], in which the evolution of a Markov process on the graph is used as a zooming lens over the structure of the network at all scales, one can detect both clique- or non clique-like communities without imposing an upper scale to the detection. Consequently, the performance of algorithms on inherently low-diameter, clique-like benchmarks may not always be indicative of equally good results in real networks with local, sparser connectivity. We illustrate our ideas with constructive examples and through the analysis of real-world networks from imaging, protein structures and the power grid, where a multiscale structure of non clique-like communities is revealed. PMID:22384178

Selected physical properties of various diesel blends

NASA Astrophysics Data System (ADS)

Hlaváčová, Zuzana; Božiková, Monika; Hlaváč, Peter; Regrut, Tomáš; Ardonová, Veronika

2018-01-01

The quality determination of biofuels requires identifying the chemical and physical parameters. The key physical parameters are rheological, thermal and electrical properties. In our study, we investigated samples of diesel blends with rape-seed methyl esters content in the range from 3 to 100%. In these, we measured basic thermophysical properties, including thermal conductivity and thermal diffusivity, using two different transient methods - the hot-wire method and the dynamic plane source. Every thermophysical parameter was measured 100 times using both methods for all samples. Dynamic viscosity was measured during the heating process under the temperature range 20-80°C. A digital rotational viscometer (Brookfield DV 2T) was used for dynamic viscosity detection. Electrical conductivity was measured using digital conductivity meter (Model 1152) in a temperature range from -5 to 30°C. The highest values of thermal parameters were reached in the diesel sample with the highest biofuel content. The dynamic viscosity of samples increased with higher concentration of bio-component rapeseed methyl esters. The electrical conductivity of blends also increased with rapeseed methyl esters content.

A High Sensitivity and Wide Dynamic Range Fiber-Optic Sensor for Low-Concentration VOC Gas Detection

PubMed Central

Khan, Md. Rajibur Rahaman; Kang, Shin-Won

2014-01-01

In this paper, we propose a volatile organic compound (VOC) gas sensing system with high sensitivity and a wide dynamic range that is based on the principle of the heterodyne frequency modulation method. According to this method, the time period of the sensing signal shift when Nile Red containing a VOC-sensitive membrane of a fiber-optic sensing element comes into contact with a VOC. This sensing membrane produces strong, fast and reversible signals when exposed to VOC gases. The response and recovery times of the proposed sensing system were less than 35 s, and good reproducibility and accuracy were obtained. PMID:25490592

Temporally increasing spatial synchrony of North American temperature and bird populations

Treesearch

Walter D. Koenig; Andrew M. Liebhold

2016-01-01

The ecological impacts of modern global climate change are detectable in a wide variety of phenomena, ranging from shifts in species ranges to changes in community composition and human disease dynamics. So far, however, little attention has been given to temporal changes in spatial synchrony—the coincident change in abundance or value across the landscape—despite the...

Fluorescence excitation-emission matrix (EEM) spectroscopy and cavity ring-down (CRD) absorption spectroscopy of oil-contaminated jet fuel using fiber-optic probes.

PubMed

Omrani, Hengameh; Barnes, Jack A; Dudelzak, Alexander E; Loock, Hans-Peter; Waechter, Helen

2012-06-21

Excitation emission matrix (EEM) and cavity ring-down (CRD) spectral signatures have been used to detect and quantitatively assess contamination of jet fuels with aero-turbine lubricating oil. The EEM spectrometer has been fiber-coupled to permit in situ measurements of jet turbine oil contamination of jet fuel. Parallel Factor (PARAFAC) analysis as well as Principal Component Analysis and Regression (PCA/PCR) were used to quantify oil contamination in a range from the limit of detection (10 ppm) to 1000 ppm. Fiber-loop cavity ring-down spectroscopy using a pulsed 355 nm laser was used to quantify the oil contamination in the range of 400 ppm to 100,000 ppm. Both methods in combination therefore permit the detection of oil contamination with a linear dynamic range of about 10,000.

Biosensing of DNA oxidative damage: a model of using glucose meter for non-glucose biomarker detection.

PubMed

Zhu, Xuena; Sarwar, Mehenur; Yue, Qiaoli; Chen, Chunying; Li, Chen-Zhong

2017-01-01

Non-glucose biomarker-DNA oxidative damage biomarker 8-hydroxy-2'-deoxyguanosine (8-OHdG) has been successfully detected using a smartphone-enabled glucose meter. Through a series of immune reactions and enzymatic reactions on a solid lateral flow platform, 8-OHdG concentration has been converted to a relative amount of glucose, and therefore can be detected by conventional glucose meter directly. The device was able to detect 8-OHdG concentrations in phosphate buffer saline as low as 1.73 ng mL -1 with a dynamic range of 1-200 ng mL -1 . Considering the inherent advantages of the personal glucose meter, the demonstration of this device, therefore, should provide new opportunities for the monitoring of a wide range of biomarkers and various target analytes in connection with different molecular recognition events.

Analysis and design of a capsule landing system and surface vehicle control system for Mars exporation

NASA Technical Reports Server (NTRS)

Frederick, D. K.; Lashmet, P. K.; Sandor, G. N.; Shen, C. N.; Smith, E. J.; Yerazunis, S. W.

1972-01-01

The problems related to the design and control of a mobile planetary vehicle to implement a systematic plan for the exploration of Mars were investigated. Problem areas receiving attention include: vehicle configuration, control, dynamics, systems and propulsion; systems analysis; navigation, terrain modeling and path selection; and chemical analysis of specimens. The following specific tasks were studied: vehicle model design, mathematical modeling of dynamic vehicle, experimental vehicle dynamics, obstacle negotiation, electromechanical controls, collapsibility and deployment, construction of a wheel tester, wheel analysis, payload design, system design optimization, effect of design assumptions, accessory optimal design, on-board computer subsystem, laser range measurement, discrete obstacle detection, obstacle detection systems, terrain modeling, path selection system simulation and evaluation, gas chromatograph/mass spectrometer system concepts, chromatograph model evaluation and improvement and transport parameter evaluation.

Analysis and design of a capsule landing system and surface vehicle control system for Mars exploration

NASA Technical Reports Server (NTRS)

Frederick, D. K.; Lashmet, P. K.; Sandor, G. N.; Shen, C. N.; Smith, E. J.; Yerazunis, S. W.

1972-01-01

Investigation of problems related to the design and control of a mobile planetary vehicle to implement a systematic plan for the exploration of Mars has been undertaken. Problem areas receiving attention include: vehicle configuration, control, dynamics, systems and propulsion; systems analysis; terrain modeling and path selection; and chemical analysis of specimens. The following specific tasks have been under study: vehicle model design, mathematical modeling of a dynamic vehicle, experimental vehicle dynamics, obstacle negotiation, electromechanical controls, collapsibility and deployment, construction of a wheel tester, wheel analysis, payload design, system design optimization, effect of design assumptions, accessory optimal design, on-board computer sybsystem, laser range measurement, discrete obstacle detection, obstacle detection systems, terrain modeling, path selection system simulation and evaluation, gas chromatograph/mass spectrometer system concepts, chromatograph model evaluation and improvement.

Evaluation of the performance of quantitative detection of the Listeria monocytogenes prfA locus with droplet digital PCR.

PubMed

Witte, Anna Kristina; Fister, Susanne; Mester, Patrick; Schoder, Dagmar; Rossmanith, Peter

2016-11-01

Fast and reliable pathogen detection is an important issue for human health. Since conventional microbiological methods are rather slow, there is growing interest in detection and quantification using molecular methods. The droplet digital polymerase chain reaction (ddPCR) is a relatively new PCR method for absolute and accurate quantification without external standards. Using the Listeria monocytogenes specific prfA assay, we focused on the questions of whether the assay was directly transferable to ddPCR and whether ddPCR was suitable for samples derived from heterogeneous matrices, such as foodstuffs that often included inhibitors and a non-target bacterial background flora. Although the prfA assay showed suboptimal cluster formation, use of ddPCR for quantification of L. monocytogenes from pure bacterial cultures, artificially contaminated cheese, and naturally contaminated foodstuff was satisfactory over a relatively broad dynamic range. Moreover, results demonstrated the outstanding detection limit of one copy. However, while poorer DNA quality, such as resulting from longer storage, can impair ddPCR, internal amplification control (IAC) of prfA by ddPCR, that is integrated in the genome of L. monocytogenes ΔprfA, showed even slightly better quantification over a broader dynamic range. Graphical Abstract Evaluating the absolute quantification potential of ddPCR targeting Listeria monocytogenes prfA.

High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector

PubMed Central

Giewekemeyer, Klaus; Philipp, Hugh T.; Wilke, Robin N.; Aquila, Andrew; Osterhoff, Markus; Tate, Mark W.; Shanks, Katherine S.; Zozulya, Alexey V.; Salditt, Tim; Gruner, Sol M.; Mancuso, Adrian P.

2014-01-01

Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 108 8-keV photons pixel−1 s−1, and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 1010 photons µm−2 s−1 within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while ‘still’ images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described. PMID:25178008

High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector.

PubMed

Giewekemeyer, Klaus; Philipp, Hugh T; Wilke, Robin N; Aquila, Andrew; Osterhoff, Markus; Tate, Mark W; Shanks, Katherine S; Zozulya, Alexey V; Salditt, Tim; Gruner, Sol M; Mancuso, Adrian P

2014-09-01

Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 10(8) 8-keV photons pixel(-1) s(-1), and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 10(10) photons µm(-2) s(-1) within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while `still' images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described.

Complexity analyses show two distinct types of nonlinear dynamics in short heart period variability recordings

PubMed Central

Porta, Alberto; Bari, Vlasta; Marchi, Andrea; De Maria, Beatrice; Cysarz, Dirk; Van Leeuwen, Peter; Takahashi, Anielle C. M.; Catai, Aparecida M.; Gnecchi-Ruscone, Tomaso

2015-01-01

Two diverse complexity metrics quantifying time irreversibility and local prediction, in connection with a surrogate data approach, were utilized to detect nonlinear dynamics in short heart period (HP) variability series recorded in fetuses, as a function of the gestational period, and in healthy humans, as a function of the magnitude of the orthostatic challenge. The metrics indicated the presence of two distinct types of nonlinear HP dynamics characterized by diverse ranges of time scales. These findings stress the need to render more specific the analysis of nonlinear components of HP dynamics by accounting for different temporal scales. PMID:25806002

Micropatterned Pyramidal Ionic Gels for Sensing Broad-Range Pressures with High Sensitivity.

PubMed

Cho, Sung Hwan; Lee, Seung Won; Yu, Seunggun; Kim, Hyeohn; Chang, Sooho; Kang, Donyoung; Hwang, Ihn; Kang, Han Sol; Jeong, Beomjin; Kim, Eui Hyuk; Cho, Suk Man; Kim, Kang Lib; Lee, Hyungsuk; Shim, Wooyoung; Park, Cheolmin

2017-03-22

The development of pressure sensors that are effective over a broad range of pressures is crucial for the future development of electronic skin applicable to the detection of a wide pressure range from acoustic wave to dynamic human motion. Here, we present flexible capacitive pressure sensors that incorporate micropatterned pyramidal ionic gels to enable ultrasensitive pressure detection. Our devices show superior pressure-sensing performance, with a broad sensing range from a few pascals up to 50 kPa, with fast response times of <20 ms and a low operating voltage of 0.25 V. Since high-dielectric-constant ionic gels were employed as constituent sensing materials, an unprecedented sensitivity of 41 kPa -1 in the low-pressure regime of <400 Pa could be realized in the context of a metal-insulator-metal platform. This broad-range capacitive pressure sensor allows for the efficient detection of pressure from a variety of sources, including sound waves, a lightweight object, jugular venous pulses, radial artery pulses, and human finger touch. This platform offers a simple, robust approach to low-cost, scalable device design, enabling practical applications of electronic skin.

Comparison of magnetic resonance imaging-compatible optical detectors for in-magnet tissue spectroscopy: photodiodes versus silicon photomultipliers

PubMed Central

El-Ghussein, Fadi; Jiang, Shudong; Pogue, Brian W.; Paulsen, Keith D.

2014-01-01

Abstract. Tissue spectroscopy inside the magnetic resonance imaging (MRI) system adds a significant value by measuring fast vascular hemoglobin responses or completing spectroscopic identification of diagnostically relevant molecules. Advances in this type of spectroscopy instrumentation have largely focused on fiber coupling into and out of the MRI; however, nonmagnetic detectors can now be placed inside the scanner with signal amplification performed remotely to the high field environment for optimized light detection. In this study, the two possible detector options, such as silicon photodiodes (PD) and silicon photomultipliers (SiPM), were systematically examined for dynamic range and wavelength performance. Results show that PDs offer 108 (160 dB) dynamic range with sensitivity down to 1 pW, whereas SiPMs have 107 (140 dB) dynamic range and sensitivity down to 10 pW. A second major difference is the spectral sensitivity of the two detectors. Here, wavelengths in the 940 nm range are efficiently captured by PDs (but not SiPMs), likely making them the superior choice for broadband spectroscopy guided by MRI. PMID:25006986

Atomic structure and transport properties of Cu50Zr45Al5 metallic liquids and glasses: Molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Zhang, Y.; Mattern, N.; Eckert, J.

2011-11-01

We have simulated the atomic structure and the transport properties of Cu50Zr45Al5 metallic liquids and glasses within a wide cooling temperature range from 2000 to 300 K, using molecular dynamics simulations. High fractions of Cu- and Al-centered full icosahedra and Zr-centered icosahedra-like clusters have been detected in both supercooled liquids and glasses. The heat capacity and linear thermal expansion coefficients of both liquids and glasses are also calculated, which have not been reported for this off-eutectic composition previously. The critical temperature (Tc) of Cu50Zr45Al5 liquids is determined to be 874.7 K by investigating the self-diffusivity using the mode coupling theory. A dynamics cross-over is detected in the vicinity of Tc, which can be reflected by different diffusion mechanisms and a remarkable deviation from the Einstein-Stokes relation. The results further suggest a fragile to strong transition of Cu50Zr45Al5 liquids between 1500 K and 1300 K upon cooling, which may result from a drastic increase of stable clusters within this temperature range.

Ghost detection and removal based on super-pixel grouping in exposure fusion

NASA Astrophysics Data System (ADS)

Jiang, Shenyu; Xu, Zhihai; Li, Qi; Chen, Yueting; Feng, Huajun

2014-09-01

A novel multi-exposure images fusion method for dynamic scenes is proposed. The commonly used techniques for high dynamic range (HDR) imaging are based on the combination of multiple differently exposed images of the same scene. The drawback of these methods is that ghosting artifacts will be introduced into the final HDR image if the scene is not static. In this paper, a super-pixel grouping based method is proposed to detect the ghost in the image sequences. We introduce the zero mean normalized cross correlation (ZNCC) as a measure of similarity between a given exposure image and the reference. The calculation of ZNCC is implemented in super-pixel level, and the super-pixels which have low correlation with the reference are excluded by adjusting the weight maps for fusion. Without any prior information on camera response function or exposure settings, the proposed method generates low dynamic range (LDR) images which can be shown on conventional display devices directly with details preserving and ghost effects reduced. Experimental results show that the proposed method generates high quality images which have less ghost artifacts and provide a better visual quality than previous approaches.

High-speed asynchronous optical sampling for high-sensitivity detection of coherent phonons

NASA Astrophysics Data System (ADS)

Dekorsy, T.; Taubert, R.; Hudert, F.; Schrenk, G.; Bartels, A.; Cerna, R.; Kotaidis, V.; Plech, A.; Köhler, K.; Schmitz, J.; Wagner, J.

2007-12-01

A new optical pump-probe technique is implemented for the investigation of coherent acoustic phonon dynamics in the GHz to THz frequency range which is based on two asynchronously linked femtosecond lasers. Asynchronous optical sampling (ASOPS) provides the performance of on all-optical oscilloscope and allows us to record optically induced lattice dynamics over nanosecond times with femtosecond resolution at scan rates of 10 kHz without any moving part in the set-up. Within 1 minute of data acquisition time signal-to-noise ratios better than 107 are achieved. We present examples of the high-sensitivity detection of coherent phonons in superlattices and of the coherent acoustic vibration of metallic nanoparticles.

Phaeton Mast Dynamics: On-Orbit Characterization of Deployable Masts

NASA Technical Reports Server (NTRS)

Michaels, Darren J.

2011-01-01

The PMD instrument is a set of three custom-designed triaxial accelerometer systems designed specifically to detect and characterize the modal dynamics of deployable masts in orbit. The instrument was designed and built as a payload for the NuSTAR spacecraft, but it is now sponsored by the Air Force Research Laboratory's DSX project. It can detect acceleration levels from 1 micro gram to 0.12g over a frequency range of 0.1Hz to 30Hz, the results of which can support future modeling and designing of deployable mast structures for space. This paper details the hardware architecture and design, calibration test and results, and current status of the PMD instrument.

Refractive index-based detection of gradient elution liquid chromatography using chip-integrated microring resonator arrays.

PubMed

Wade, James H; Bailey, Ryan C

2014-01-07

Refractive index-based sensors offer attractive characteristics as nondestructive and universal detectors for liquid chromatographic separations, but a small dynamic range and sensitivity to minor thermal perturbations limit the utility of commercial RI detectors for many potential applications, especially those requiring the use of gradient elutions. As such, RI detectors find use almost exclusively in sample abundant, isocratic separations when interfaced with high-performance liquid chromatography. Silicon photonic microring resonators are refractive index-sensitive optical devices that feature good sensitivity and tremendous dynamic range. The large dynamic range of microring resonators allows the sensors to function across a wide spectrum of refractive indices, such as that encountered when moving from an aqueous to organic mobile phase during a gradient elution, a key analytical advantage not supported in commercial RI detectors. Microrings are easily configured into sensor arrays, and chip-integrated control microrings enable real-time corrections of thermal drift. Thermal controls allow for analyses at any temperature and, in the absence of rigorous temperature control, obviates extended detector equilibration wait times. Herein, proof of concept isocratic and gradient elution separations were performed using well-characterized model analytes (e.g., caffeine, ibuprofen) in both neat buffer and more complex sample matrices. These experiments demonstrate the ability of microring arrays to perform isocratic and gradient elutions under ambient conditions, avoiding two major limitations of commercial RI-based detectors and maintaining comparable bulk RI sensitivity. Further benefit may be realized in the future through selective surface functionalization to impart degrees of postcolumn (bio)molecular specificity at the detection phase of a separation. The chip-based and microscale nature of microring resonators also make it an attractive potential detection technology that could be integrated within lab-on-a-chip and microfluidic separation devices.

A Fiber-Optic Interferometric Tri-Component Geophone for Ocean Floor Seismic Monitoring

PubMed Central

Chen, Jiandong; Chang, Tianying; Fu, Qunjian; Lang, Jinpeng; Gao, Wenzhi; Wang, Zhongmin; Yu, Miao; Zhang, Yanbo; Cui, Hong-Liang

2016-01-01

For the implementation of an all fiber observation network for submarine seismic monitoring, a tri-component geophone based on Michelson interferometry is proposed and tested. A compliant cylinder-based sensor head is analyzed with finite element method and tested. The operation frequency ranges from 2 Hz to 150 Hz for acceleration detection, employing a phase generated carrier demodulation scheme, with a responsivity above 50 dB re rad/g for the whole frequency range. The transverse suppression ratio is about 30 dB. The system noise at low frequency originated mainly from the 1/f fluctuation, with an average system noise level −123.55 dB re rad/Hz ranging from 0 Hz to 500 Hz. The minimum detectable acceleration is about 2 ng/Hz, and the dynamic range is above 116 dB. PMID:28036011

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

Shanks, Katherine S.; Philipp, Hugh T.; Weiss, Joel T.

Experiments at storage ring light sources as well as at next-generation light sources increasingly require detectors capable of high dynamic range operation, combining low-noise detection of single photons with large pixel well depth. XFEL sources in particular provide pulse intensities sufficiently high that a purely photon-counting approach is impractical. The High Dynamic Range Pixel Array Detector (HDR-PAD) project aims to provide a dynamic range extending from single-photon sensitivity to 10{sup 6} photons/pixel in a single XFEL pulse while maintaining the ability to tolerate a sustained flux of 10{sup 11} ph/s/pixel at a storage ring source. Achieving these goals involves themore » development of fast pixel front-end electronics as well as, in the XFEL case, leveraging the delayed charge collection due to plasma effects in the sensor. A first prototype of essential electronic components of the HDR-PAD readout ASIC, exploring different options for the pixel front-end, has been fabricated. Here, the HDR-PAD concept and preliminary design will be described.« less

Calibration of high-dynamic-range, finite-resolution x-ray pulse-height spectrometers for extracting electron energy distribution data from the PFRC-2 device

NASA Astrophysics Data System (ADS)

Swanson, C.; Jandovitz, P.; Cohen, S. A.

2017-10-01

Knowledge of the full x-ray energy distribution function (XEDF) emitted from a plasma over a large dynamic range of energies can yield valuable insights about the electron energy distribution function (EEDF) of that plasma and the dynamic processes that create them. X-ray pulse height detectors such as Amptek's X-123 Fast SDD with Silicon Nitride window can detect x-rays in the range of 200eV to 100s of keV. However, extracting EEDF from this measurement requires precise knowledge of the detector's response function. This response function, including the energy scale calibration, the window transmission function, and the resolution function, can be measured directly. We describe measurements of this function from x-rays from a mono-energetic electron beam in a purpose-built gas-target x-ray tube. Large-Z effects such as line radiation, nuclear charge screening, and polarizational Bremsstrahlung are discussed.

Nanoposition sensors with superior linear response to position and unlimited travel ranges

NASA Astrophysics Data System (ADS)

Lee, Sheng-Chiang; Peters, Randall D.

2009-04-01

With the advancement in nanotechnology, the ability of positioning/measuring at subnanometer scale has been one of the most critical issues for the nanofabrication industry and researchers using scanning probe microscopy. Commercial nanopositioners have achieved direct measurements at the scale of 0.01 nm with capacitive sensing metrology. However, the commercial sensors have small dynamic ranges (up to only a few hundred micrometers) and are relatively large in size (centimeters in the transverse directions to the motion), which is necessary for healthy signal detections but making it difficult to use on smaller devices. This limits applications in which large materials (on the scale of centimeters or greater) are handled with needs of subnanometer resolutions. What has been done in the past is to combine the fine and coarse translation stages with different dynamic ranges to simultaneously achieve long travel range and high spatial resolution. In this paper, we present a novel capacitive position sensing metrology with ultrawide dynamic range from subnanometer to literally any practically desired length for a translation stage. This sensor will greatly simplify the task and enhance the performance of direct metrology in a hybrid translational stage covering translation tasks from subnanometer to centimeters.

Dynamic SERS nanosensor for neurotransmitter sensing near neurons.

PubMed

Lussier, Félix; Brulé, Thibault; Bourque, Marie-Josée; Ducrot, Charles; Trudeau, Louis-Éric; Masson, Jean-François

2017-12-04

Current electrophysiology and electrochemistry techniques have provided unprecedented understanding of neuronal activity. However, these techniques are suited to a small, albeit important, panel of neurotransmitters such as glutamate, GABA and dopamine, and these constitute only a subset of the broader range of neurotransmitters involved in brain chemistry. Surface-enhanced Raman scattering (SERS) provides a unique opportunity to detect a broader range of neurotransmitters in close proximity to neurons. Dynamic SERS (D-SERS) nanosensors based on patch-clamp-like nanopipettes decorated with gold nanoraspberries can be located accurately under a microscope using techniques analogous to those used in current electrophysiology or electrochemistry experiments. In this manuscript, we demonstrate that D-SERS can measure in a single experiment ATP, glutamate (glu), acetylcholine (ACh), GABA and dopamine (DA), among other neurotransmitters, with the potential for detecting a greater number of neurotransmitters. The SERS spectra of these neurotransmitters were identified with a barcoding data processing method and time series of the neurotransmitter levels were constructed. The D-SERS nanosensor was then located near cultured mouse dopaminergic neurons. The detection of neurotransmitters was performed in response to a series of K + depolarisations, and allowed the detection of elevated levels of both ATP and dopamine. Control experiments were also performed near glial cells, showing only very low basal detection neurotransmitter events. This paper demonstrates the potential of D-SERS to detect neurotransmitter secretion events near living neurons, but also constitutes a strong proof-of-concept for the broad application of SERS to the detection of secretion events by neurons or other cell types in order to study normal or pathological cell functions.

Wide-field surface plasmon microscopy of nano- and microparticles: features, benchmarking, limitations, and bioanalytical applications

NASA Astrophysics Data System (ADS)

Nizamov, Shavkat; Scherbahn, Vitali; Mirsky, Vladimir M.

2017-05-01

Detection of nano- and micro-particles is an important task for chemical analytics, food industry, biotechnology, environmental monitoring and many other fields of science and industry. For this purpose, a method based on the detection and analysis of minute signals in surface plasmon resonance images due to adsorption of single nanopartciles was developed. This new technology allows one a real-time detection of interaction of single nano- and micro-particles with sensor surface. Adsorption of each nanoparticle leads to characteristic diffraction image whose intensity depends on the size and chemical composition of the particle. The adsorption rate characterizes volume concentration of nano- and micro-particles. Large monitored surface area of sensor enables a high dynamic range of counting and to a correspondingly high dynamic range in concentration scale. Depending on the type of particles and experimental conditions, the detection limit for aqueous samples can be below 1000 particles per microliter. For application of method in complex media, nanoparticle images are discriminated from image perturbations due to matrix components. First, the characteristic SPRM images of nanoparticles (templates) are collected in aqueous suspensions or spiked real samples. Then, the detection of nanoparticles in complex media using template matching is performed. The detection of various NPs in consumer products like cosmetics, mineral water, juices, and wines was shown at sub-ppb level. The method can be applied for ultrasensitive detection and analysis of nano- and micro-particles of biological (bacteria, viruses, endosomes), biotechnological (liposomes, protein nanoparticles for drug delivery) or technical origin.

Dynamic planar solid phase microextraction-ion mobility spectrometry for rapid field air sampling and analysis of illicit drugs and explosives.

PubMed

Guerra-Diaz, Patricia; Gura, Sigalit; Almirall, José R

2010-04-01

A preconcentration device that targets the volatile chemical signatures associated with illicit drugs and explosives (high and low) has been designed to fit in the inlet of an ion mobility spectrometer (IMS). This is the first reporting of a fast and sensitive method for dynamic sampling of large volumes of air using planar solid phase microextraction (PSPME) incorporating a high surface area for absorption of analytes onto a sol-gel polydimethylsiloxane (PDMS) coating for direct thermal desorption into an IMS. This device affords high extraction efficiencies due to strong retention properties at ambient temperature, resulting in the detection of analyte concentrations in the parts per trillion range when as low as 3.5 L of air are sampled over the course of 10 s (absolute mass detection of less than a nanogram). Dynamic PSPME was used to sample the headspace over the following: 3,4-methylenedioxymethamphetamine (MDMA) tablets resulting in the detection of 12-40 ng of piperonal, high explosives (Pentolite) resulting in the detection of 0.6 ng of 2,4,6-trinitrotoluene (TNT), and low explosives (several smokeless powders) resulting in the detection of 26-35 ng of 2,4-dinitrotoluene (2,4-DNT) and 11-74 ng of diphenylamine (DPA).

Development and Validation of a Rotor-Gene Real-Time PCR Assay for Detection, Identification, and Quantification of Chlamydia trachomatis in a Single Reaction

PubMed Central

Jalal, Hamid; Stephen, Hannah; Curran, Martin D.; Burton, Janet; Bradley, Michelle; Carne, Christopher

2006-01-01

A multitarget real-time PCR (MRT-PCR) for detection of Chlamydia trachomatis DNA was developed and validated. There were three targets for amplification in a single reaction: the cryptic plasmid (CP), the major outer membrane protein (MOMP) gene, and an internal control. The assay had the following characteristics: (i) detection and confirmation of the presence of C. trachomatis DNA in a single reaction, (ii) detection of all genovars of C. trachomatis without any cross-reactivity with pathogenic bacteria or commensal organisms of the oropharynx and genital tract, (iii) a 95% probability of detection with three copies of MOMP and one copy of CP per reaction mixture, (iv) identification of the inhibition of amplification, (v) a quantitative dynamic range of 25 to 250,000 genome copies per reaction mixture, (vi) high intra- and interassay reproducibilities, and (vii) correct identification of all samples in the validation panel. There were 146 COBAS Amplicor PCR (Amplicor PCR)-positive samples and 122 Amplicor PCR-negative samples in the panel. MRT-PCR detected CP DNA alone in 6 (4%) Amplicor PCR-positive samples and both CP and MOMP DNAs in 140 (96%) of 146 Amplicor PCR-positive samples. The quantity of MOMP DNA in 95 (68%) of 140 samples was within the dynamic range of the assay. The median C. trachomatis load in these samples was 321 genome copies per reaction mixture (range, 26 to 40,137 genome copies per reaction mixture). Due to the inclusion of two different C. trachomatis-specific targets, the assay confirmed 259 (97%) of 268 results in a single reaction. This assay could be used in the qualitative format for the routine detection of C. trachomatis and in the quantitative format for study of the pathogenesis of C. trachomatis-associated diseases. The assay demonstrated the potential to eliminate the need for confirmatory testing in almost all samples, thus reducing the turnaround time and the workload. PMID:16390971

Blood flow measurement of human skeletal muscle during various exercise intensity using diffuse correlation spectroscopy (DCS)

NASA Astrophysics Data System (ADS)

Murakami, Yuya; Ono, Yumie; Ichinose, Masashi

2017-02-01

We studied blood flow dynamics of active skeletal muscle using diffuse correlation spectroscopy (DCS), an emerging optical modality that is suitable for noninvasive quantification of microcirculation level in deep tissue. Seven healthy subjects conducted 0.5 Hz dynamic handgrip exercise for 3 minutes at intensities of 10, 20, 30, and 50 % of maximal voluntary contraction (MVC). DCS could detect the time-dependent increase of the blood flow response of the forearm muscle for continuous exercises, and the increase ratios of the mean blood flow through the exercise periods showed good correlation with the exercise intensities. We also compared blood flow responses detected from DCS with two different photon sampling rates and found that an appropriate photon sampling rates should be selected to follow the wide-ranged increase in the muscle blood flow with dynamic exercise. Our results demonstrate the possibility for utilizing DCS in a field of sports medicine to noninvasively evaluate the dynamics of blood flow in the active muscles.

Sensory determinants of valve rhythm dynamics provide in situ biodetection of copper in aquatic environments.

PubMed

Jou, Li-John; Chen, Bo-Ching; Chen, Wei-Yu; Liao, Chung-Min

2016-03-01

This study successfully applied an improved valvometry technique to measure waterborne copper (Cu), based on valve activity dynamics of the freshwater clam Corbicula fluminea. The improved valvometry technique allows the use of free-range bivalves and avoids causing stresses from experimental artifacts. The proposed daily valve rhythm models and a toxicodynamics-based Hill model were linked to predict valve dynamic responses under different Cu exposures with a circadian valve rhythm endpoint. Cu-specific detection threshold was 5.6 (95 % CI 2.1-9.3) and 19.5 (14.6-24.3) μg L(-1) for C. fluminea, based on response times of 300 and 30 min, respectively. Upon exposure to Cu concentrations in excess of 50 μg L(-1), the alteration of valve rhythm behavior was correlated with Cu concentration within 30 min, indicating notable sensing ability. This study outlines the feasibility of an in situ early warning dynamic biomonitoring system for detection of waterborne Cu based on circadian valve activities of C. fluminea.

Extended range radiation dose-rate monitor

DOEpatents

Valentine, Kenneth H.

1988-01-01

An extended range dose-rate monitor is provided which utilizes the pulse pileup phenomenon that occurs in conventional counting systems to alter the dynamic response of the system to extend the dose-rate counting range. The current pulses from a solid-state detector generated by radiation events are amplified and shaped prior to applying the pulses to the input of a comparator. The comparator generates one logic pulse for each input pulse which exceeds the comparator reference threshold. These pulses are integrated and applied to a meter calibrated to indicate the measured dose-rate in response to the integrator output. A portion of the output signal from the integrator is fed back to vary the comparator reference threshold in proportion to the output count rate to extend the sensitive dynamic detection range by delaying the asymptotic approach of the integrator output toward full scale as measured by the meter.

Internally Controlled, Multiplex Real-Time Reverse Transcription PCR for Dengue Virus and Yellow Fever Virus Detection.

PubMed

Rojas, Alejandra; Diagne, Cheikh T; Stittleburg, Victoria D; Mohamed-Hadley, Alisha; de Guillén, Yvalena Arévalo; Balmaseda, Angel; Faye, Oumar; Faye, Ousmane; Sall, Amadou A; Harris, Eva; Pinsky, Benjamin A; Waggoner, Jesse J

2018-04-02

The differential diagnosis of dengue virus (DENV) and yellow fever virus (YFV) infections in endemic areas is complicated by nonspecific early clinical manifestations. In this study, we describe an internally controlled, multiplex real-time reverse transcription PCR (rRT-PCR) for the detection of DENV and YFV. The DENV-YFV assay demonstrated specific detection and had a dynamic range of 2.0-8.0 log 10 copies/μL of eluate for each DENV serotype and YFV. Clinical performance was similar to a published pan-DENV assay: 48/48 acute-phase samples from dengue cases were detected in both assays. For YFV detection, mock samples were prepared with nine geographically diverse YFV isolates over a range of concentrations. The DENV-YFV assay detected 62/65 replicates, whereas 54/65 were detected using a reference YFV rRT-PCR. Given the reemergence of DENV and YFV in areas around the world, the DENV-YFV assay should be a useful tool to narrow the differential diagnosis and provide early case detection.

Formulation of image quality prediction criteria for the Viking lander camera

NASA Technical Reports Server (NTRS)

Huck, F. O.; Jobson, D. J.; Taylor, E. J.; Wall, S. D.

1973-01-01

Image quality criteria are defined and mathematically formulated for the prediction computer program which is to be developed for the Viking lander imaging experiment. The general objective of broad-band (black and white) imagery to resolve small spatial details and slopes is formulated as the detectability of a right-circular cone with surface properties of the surrounding terrain. The general objective of narrow-band (color and near-infrared) imagery to observe spectral characteristics if formulated as the minimum detectable albedo variation. The general goal to encompass, but not exceed, the range of the scene radiance distribution within single, commandable, camera dynamic range setting is also considered.

Scaling Exponents in Financial Markets

NASA Astrophysics Data System (ADS)

Kim, Kyungsik; Kim, Cheol-Hyun; Kim, Soo Yong

2007-03-01

We study the dynamical behavior of four exchange rates in foreign exchange markets. A detrended fluctuation analysis (DFA) is applied to detect the long-range correlation embedded in the non-stationary time series. It is for our case found that there exists a persistent long-range correlation in volatilities, which implies the deviation from the efficient market hypothesis. Particularly, the crossover is shown to exist in the scaling behaviors of the volatilities.

A paper-based resonance energy transfer nucleic acid hybridization assay using upconversion nanoparticles as donors and quantum dots as acceptors.

PubMed

Doughan, Samer; Uddayasankar, Uvaraj; Krull, Ulrich J

2015-06-09

Monodisperse aqueous upconverting nanoparticles (UCNPs) were covalently immobilized on aldehyde modified cellulose paper via reduction amination to develop a luminescence resonance energy transfer (LRET)-based nucleic acid hybridization assay. This first account of covalent immobilization of UCNPs on paper for a bioassay reports an optically responsive method that is sensitive, reproducible and robust. The immobilized UCNPs were decorated with oligonucleotide probes to capture HPRT1 housekeeping gene fragments, which in turn brought reporter conjugated quantum dots (QDs) in close proximity to the UCNPs for LRET. This sandwich assay could detect unlabeled oligonucleotide target, and had a limit of detection of 13 fmol and a dynamic range spanning nearly 3 orders of magnitude. The use of QDs, which are excellent LRET acceptors, demonstrated improved sensitivity, limit of detection, dynamic range and selectivity compared to similar assays that have used molecular fluorophores as acceptors. The selectivity of the assay was attributed to the decoration of the QDs with polyethylene glycol to eliminate non-specific adsorption. The kinetics of hybridization were determined to be diffusion limited and full signal development occurred within 3 min. Copyright © 2015 Elsevier B.V. All rights reserved.

Voltammetric behavior of dopamine at a glassy carbon electrode modified with NiFe(2)O(4) magnetic nanoparticles decorated with multiwall carbon nanotubes.

PubMed

Ensafi, Ali A; Arashpour, B; Rezaei, B; Allafchian, Ali R

2014-06-01

Voltammetric behavior of dopamine was studied on a glassy carbon electrode (GCE) modified-NiFe(2)O(4) magnetic nanoparticles decorated with multiwall carbon nanotubes. Impedance spectroscopy and cyclic voltammetry were used to characterize the behavior of dopamine at the surface of modified-GCE. The modified electrode showed a synergic effect toward the oxidation of dopamine. The oxidation peak current is increased linearly with the dopamine concentration (at pH7.0) in wide dynamic ranges of 0.05-6.0 and 6.0-100μmolL(-1) with a detection limit of 0.02μmolL(-1), using differential pulse voltammetry. The selectivity of the method was studied and the results showed that the modified electrode is free from interference of organic compounds especially ascorbic acid, uric acid, cysteine and urea. Its applicability in the determination of dopamine in pharmaceutical, urine samples and human blood serum was also evaluated. The proposed electrochemical sensor has appropriate properties such as high selectivity, low detection limit and wide linear dynamic range when compared with that of the previous reported papers for dopamine detection. Copyright © 2014 Elsevier B.V. All rights reserved.

Optical dynamic range maximization for humidity sensing by controlling growth of zinc oxide nanorods

NASA Astrophysics Data System (ADS)

Yusof, Haziezol Helmi Mohd; Harun, Sulaiman Wadi; Dimyati, Kaharudin; Bora, Tanujjal; Mohammed, Waleed S.; Dutta, Joydeep

2018-07-01

An experimental study of the dynamic range maximization with Zinc Oxide (ZnO) nanorods coated glass substrates for humidity and vapor sensing is reported. Growth time of the nanorods and the length of the coated segments were controlled to study the differences between a reference environmental condition (normal humidity or dry condition) and water vapor concentrations. In order to achieve long dynamic range of detection with respect to nanorods coverage, several substrates with triangular patterns of ZnO nanostructures were fabricated by selective hydrothermal growth over different durations of time (5 h, 10 h and 15 h). It was found that maximum dynamic range for the humidity sensing occurs for the combination parameters of normalized length (Z) of 0.23 and normalized scattering coefficient (ζ) of 0.3. A reduction in transmittance by 38% at humidity levels of 80% with reference point as 50% humidity was observed. The results could be correlated to a first order approximation model that assumes uniform growth and the optimum operating conditions for humidity sensing device. This study provides an option to correlate ZnO growth conditions for different vapor sensing applications which can set a platform for compact sensors where modulation of light intensity is followed.

High Dynamic Range Characterization of the Trauma Patient Plasma Proteome

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

Liu, Tao; Qian, Weijun; Gritsenko, Marina A.

2006-06-08

While human plasma represents an attractive sample for disease biomarker discovery, the extreme complexity and large dynamic range in protein concentrations present significant challenges for characterization, candidate biomarker discovery, and validation. Herein, we describe a strategy that combines immunoaffinity subtraction and chemical fractionation based on cysteinyl peptide and N-glycopeptide captures with 2D-LC-MS/MS to increase the dynamic range of analysis for plasma. Application of this ''divide-and-conquer'' strategy to trauma patient plasma significantly improved the overall dynamic range of detection and resulted in confident identification of 22,267 unique peptides from four different peptide populations (cysteinyl peptides, non-cysteinyl peptides, N-glycopeptides, and non-glycopeptides) thatmore » covered 3654 nonredundant proteins. Numerous low-abundance proteins were identified, exemplified by 78 ''classic'' cytokines and cytokine receptors and by 136 human cell differentiation molecules. Additionally, a total of 2910 different N-glycopeptides that correspond to 662 N-glycoproteins and 1553 N-glycosylation sites were identified. A panel of the proteins identified in this study is known to be involved in inflammation and immune responses. This study established an extensive reference protein database for trauma patients, which provides a foundation for future high-throughput quantitative plasma proteomic studies designed to elucidate the mechanisms that underlie systemic inflammatory responses.« less

Ratiometric Matryoshka biosensors from a nested cassette of green- and orange-emitting fluorescent proteins.

PubMed

Ast, Cindy; Foret, Jessica; Oltrogge, Luke M; De Michele, Roberto; Kleist, Thomas J; Ho, Cheng-Hsun; Frommer, Wolf B

2017-09-05

Sensitivity, dynamic and detection range as well as exclusion of expression and instrumental artifacts are critical for the quantitation of data obtained with fluorescent protein (FP)-based biosensors in vivo. Current biosensors designs are, in general, unable to simultaneously meet all these criteria. Here, we describe a generalizable platform to create dual-FP biosensors with large dynamic ranges by employing a single FP-cassette, named GO-(Green-Orange) Matryoshka. The cassette nests a stable reference FP (large Stokes shift LSSmOrange) within a reporter FP (circularly permuted green FP). GO- Matryoshka yields green and orange fluorescence upon blue excitation. As proof of concept, we converted existing, single-emission biosensors into a series of ratiometric calcium sensors (MatryoshCaMP6s) and ammonium transport activity sensors (AmTryoshka1;3). We additionally identified the internal acid-base equilibrium as a key determinant of the GCaMP dynamic range. Matryoshka technology promises flexibility in the design of a wide spectrum of ratiometric biosensors and expanded in vivo applications.Single fluorescent protein biosensors are susceptible to expression and instrumental artifacts. Here Ast et al. describe a dual fluorescent protein design whereby a reference fluorescent protein is nested within a reporter fluorescent protein to control for such artifacts while preserving sensitivity and dynamic range.

A high dynamic range method for the direct readout of a dynamic phase change in homodyne interferometers

NASA Astrophysics Data System (ADS)

Marçal, L. A. P.; Kitano, C.; Higuti, R. T.; Nader, G.; Silva, E. C. N.

2012-12-01

Piezoelectric flextensional actuators (PFAs) are an efficient alternative to systems that demand nano-positioning of devices, such as in nanotechnology. Optical techniques constitute an excellent choice for contactless measurement of nano-displacements. In particular, optical interferometry constitutes an adequate choice for characterizing PFAs. There are several types of interferometers, as well as optical phase demodulation methods, used in practice. One interesting class of demodulation methods uses the spectrum of the photo-detected signal and its intrinsic properties when there is a harmonically varying time-domain modulating signal. In this work, a low cost homodyne Michelson interferometer, associated with simple electronic circuits for signal conditioning and acquisition, is used. A novel dynamic phase demodulation method, named Jm&Jm + 2, is proposed, which uses only the magnitude spectrum of the photo-detected signal, without the need to know its phase spectrum. The method is passive, direct, self-consistent, without problems of phase ambiguity and immune to fading, and presents a dynamic range from 0.45 to 100 rad displacements (between 22.6 nm and 5 µm, for λ = 632.8 nm). When applied to the measurement of half-wave voltage in a proof-of-concept Pockels cell, it presents errors smaller than 0.9% when compared to theory. For the estimation of PFA displacement, it allows the measurement of linearity and frequency response curves, with excellent results.

Lightweight fiber optic microphones and accelerometers

NASA Astrophysics Data System (ADS)

Bucaro, J. A.; Lagakos, N.

2001-06-01

We have designed, fabricated, and tested two lightweight fiber optic sensors for the dynamic measurement of acoustic pressure and acceleration. These sensors, one a microphone and the other an accelerometer, are required for active blanket sound control technology under development in our laboratory. The sensors were designed to perform to certain specifications dictated by our active sound control application and to do so without exhibiting sensitivity to the high electrical voltages expected to be present. Furthermore, the devices had to be small (volumes less than 1.5 cm3) and light (less than 2 g). To achieve these design criteria, we modified and extended fiber optic reflection microphone and fiber microbend displacement device designs reported in the literature. After fabrication, the performances of each sensor type were determined from measurements made in a dynamic pressure calibrator and on a shaker table. The fiber optic microbend accelerometer, which weighs less than 1.8 g, was found to meet all performance goals including 1% linearity, 90 dB dynamic range, and a minimum detectable acceleration of 0.2 mg/√Hz . The fiber optic microphone, which weighs less than 1.3 g, also met all goals including 1% linearity, 85 dB dynamic range, and a minimum detectable acoustic pressure level of 0.016 Pa/√Hz . In addition to our specific use in active sound control, these sensors appear to have application in a variety of other areas.

Control range: a controllability-based index for node significance in directed networks

NASA Astrophysics Data System (ADS)

Wang, Bingbo; Gao, Lin; Gao, Yong

2012-04-01

While a large number of methods for module detection have been developed for undirected networks, it is difficult to adapt them to handle directed networks due to the lack of consensus criteria for measuring the node significance in a directed network. In this paper, we propose a novel structural index, the control range, motivated by recent studies on the structural controllability of large-scale directed networks. The control range of a node quantifies the size of the subnetwork that the node can effectively control. A related index, called the control range similarity, is also introduced to measure the structural similarity between two nodes. When applying the index of control range to several real-world and synthetic directed networks, it is observed that the control range of the nodes is mainly influenced by the network's degree distribution and that nodes with a low degree may have a high control range. We use the index of control range similarity to detect and analyze functional modules in glossary networks and the enzyme-centric network of homo sapiens. Our results, as compared with other approaches to module detection such as modularity optimization algorithm, dynamic algorithm and clique percolation method, indicate that the proposed indices are effective and practical in depicting structural and modular characteristics of sparse directed networks.

A Low-Noise, Wideband Preamplifier for a Fourier-Transform Ion Cyclotron Resonance Mass Spectrometer

PubMed Central

Mathur, Raman; Knepper, Ronald W.; O'Connor, Peter B.

2009-01-01

FTMS performance parameters such as limits of detection, dynamic range, sensitivity, and even mass accuracy and resolution can be greatly improved by enhancing its detection circuit. An extended investigation of significant design considerations for optimal signal-to-noise ratio in an FTMS detection circuit are presented. A low noise amplifier for an FTMS is developed based on the discussed design rules. The amplifier has a gain of ≈ 3500 and a bandwidth of 10 kHz - 1 MHz corresponding to m/z range of 100 Da to 10 kDa (at 7 Tesla). The performance of the amplifier was tested on a MALDI-FTMS, and has demonstrated a 25-fold reduction in noise in a mass spectrum of C60 compared to that of a commercial amplifier. PMID:18029195

Carbohydrate and alditol analysis by high-performance anion-exchange chromatography coupled with electrochemical detection at a cobalt-modified electrode.

PubMed

Casella, Innocenzo G; Contursi, Michela

2003-07-01

A cobalt oxyhydroxide film dispersed on a carbon electrode surface was characterized and proposed as an amperometric sensor for determination of alditols and carbohydrates in flowing streams. Complex mixtures of carbohydrates were separated by anion-exchange chromatography using a moderately alkaline solution as mobile phase. The cobalt modified electrode (GC-Co) was employed under a constant applied potential of 0.5 V (vs Ag/AgCl). Under these experimental conditions the detection limits (S/N=3) for all analyzed electroactive molecules ranged between 0.3 micromol L(-1) and 1.5 micromol L(-1) and the dynamic linear ranges spanned generally three orders of magnitude above the relevant detection limits. Analytical determinations of carbohydrates and alditols in red and white wines, are reported.

Organic electrochemical transistor based immunosensor for prostate specific antigen (PSA) detection using gold nanoparticles for signal amplification.

PubMed

Kim, Duck-Jin; Lee, Nae-Eung; Park, Joon-Shik; Park, In-Jun; Kim, Jung-Gu; Cho, Hyoung J

2010-07-15

We demonstrated a highly sensitive organic electrochemical transistor (OECT) based immunosensor with a low detection limit for prostate specific antigen/alpha1-antichymotrypsin (PSA-ACT) complex. The poly(styrenesulfonate) doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) based OECT with secondary antibody conjugated gold nanoparticles (AuNPs) provided a detection limit of the PSA-ACT complex as low as 1pg/ml, as well as improved sensitivity and a dynamic range, due to the role of AuNPs in the signal amplification. The sensor performances were particularly improved in the lower concentration range where the detection is clinically important for the preoperative diagnosis and screening of prostate cancer. This result shows that the OECT-based immunosensor can be used as a transducer platform acceptable to the point-of-care (POC) diagnostic systems and demonstrates adaptability of organic electronics to clinical applications. Copyright (c) 2010 Elsevier B.V. All rights reserved.

The use of compressive sensing and peak detection in the reconstruction of microtubules length time series in the process of dynamic instability.

PubMed

Mahrooghy, Majid; Yarahmadian, Shantia; Menon, Vineetha; Rezania, Vahid; Tuszynski, Jack A

2015-10-01

Microtubules (MTs) are intra-cellular cylindrical protein filaments. They exhibit a unique phenomenon of stochastic growth and shrinkage, called dynamic instability. In this paper, we introduce a theoretical framework for applying Compressive Sensing (CS) to the sampled data of the microtubule length in the process of dynamic instability. To reduce data density and reconstruct the original signal with relatively low sampling rates, we have applied CS to experimental MT lament length time series modeled as a Dichotomous Markov Noise (DMN). The results show that using CS along with the wavelet transform significantly reduces the recovery errors comparing in the absence of wavelet transform, especially in the low and the medium sampling rates. In a sampling rate ranging from 0.2 to 0.5, the Root-Mean-Squared Error (RMSE) decreases by approximately 3 times and between 0.5 and 1, RMSE is small. We also apply a peak detection technique to the wavelet coefficients to detect and closely approximate the growth and shrinkage of MTs for computing the essential dynamic instability parameters, i.e., transition frequencies and specially growth and shrinkage rates. The results show that using compressed sensing along with the peak detection technique and wavelet transform in sampling rates reduces the recovery errors for the parameters. Copyright © 2015 Elsevier Ltd. All rights reserved.

A simplified dynamic model of the T700 turboshaft engine

NASA Technical Reports Server (NTRS)

Duyar, Ahmet; Gu, Zhen; Litt, Jonathan S.

1992-01-01

A simplified open-loop dynamic model of the T700 turboshaft engine, valid within the normal operating range of the engine, is developed. This model is obtained by linking linear state space models obtained at different engine operating points. Each linear model is developed from a detailed nonlinear engine simulation using a multivariable system identification and realization method. The simplified model may be used with a model-based real time diagnostic scheme for fault detection and diagnostics, as well as for open loop engine dynamics studies and closed loop control analysis utilizing a user generated control law.

Corticomuscular synchronization with small and large dynamic force output

PubMed Central

Andrykiewicz, Agnieszka; Patino, Luis; Naranjo, Jose Raul; Witte, Matthias; Hepp-Reymond, Marie-Claude; Kristeva, Rumyana

2007-01-01

Background Over the last few years much research has been devoted to investigating the synchronization between cortical motor and muscular activity as measured by EEG/MEG-EMG coherence. The main focus so far has been on corticomuscular coherence (CMC) during static force condition, for which coherence in beta-range has been described. In contrast, we showed in a recent study [1] that dynamic force condition is accompanied by gamma-range CMC. The modulation of the CMC by various dynamic force amplitudes, however, remained uninvestigated. The present study addresses this question. We examined eight healthy human subjects. EEG and surface EMG were recorded simultaneously. The visuomotor task consisted in isometric compensation for 3 forces (static, small and large dynamic) generated by a manipulandum. The CMC, the cortical EEG spectral power (SP), the EMG SP and the errors in motor performance (as the difference between target and exerted force) were analyzed. Results For the static force condition we found the well-documented, significant beta-range CMC (15–30 Hz) over the contralateral sensorimotor cortex. Gamma-band CMC (30–45 Hz) occurred in both small and large dynamic force conditions without any significant difference between both conditions. Although in some subjects beta-range CMC was observed during both dynamic force conditions no significant difference between conditions could be detected. With respect to the motor performance, the lowest errors were obtained in the static force condition and the highest ones in the dynamic condition with large amplitude. However, when we normalized the magnitude of the errors to the amplitude of the applied force (relative errors) no significant difference between both dynamic conditions was observed. Conclusion These findings confirm that during dynamic force output the corticomuscular network oscillates at gamma frequencies. Moreover, we show that amplitude modulation of dynamic force has no effect on the gamma CMC in the low force range investigated. We suggest that gamma CMC is rather associated with the internal state of the sensorimotor system as supported by the unchanged relative error between both dynamic conditions. PMID:18042289

Dynamic nuclear magnetic resonance field sensing with part-per-trillion resolution

NASA Astrophysics Data System (ADS)

Gross, Simon; Barmet, Christoph; Dietrich, Benjamin E.; Brunner, David O.; Schmid, Thomas; Pruessmann, Klaas P.

2016-12-01

High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude. The relative sensitivity thus achieved amounts to 1 part per trillion (10-12). To exemplify this capability we demonstrate the direct detection and relaxometry of nuclear polarization and real-time recording of dynamic susceptibility effects related to human heart function. Enhanced high-field magnetometry will generally permit a fresh look at magnetic phenomena that scale with field strength. It also promises to facilitate the development and operation of high-field magnets.

Digital optical tomography system for dynamic breast imaging

NASA Astrophysics Data System (ADS)

Flexman, Molly L.; Khalil, Michael A.; Al Abdi, Rabah; Kim, Hyun K.; Fong, Christopher J.; Desperito, Elise; Hershman, Dawn L.; Barbour, Randall L.; Hielscher, Andreas H.

2011-07-01

Diffuse optical tomography has shown promising results as a tool for breast cancer screening and monitoring response to chemotherapy. Dynamic imaging of the transient response of the breast to an external stimulus, such as pressure or a respiratory maneuver, can provide additional information that can be used to detect tumors. We present a new digital continuous-wave optical tomography system designed to simultaneously image both breasts at fast frame rates and with a large number of sources and detectors. The system uses a master-slave digital signal processor-based detection architecture to achieve a dynamic range of 160 dB and a frame rate of 1.7 Hz with 32 sources, 64 detectors, and 4 wavelengths per breast. Included is a preliminary study of one healthy patient and two breast cancer patients showing the ability to identify an invasive carcinoma based on the hemodynamic response to a breath hold.

An atomic magnetometer with autonomous frequency stabilization and large dynamic range

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

Pradhan, S., E-mail: spradhan@barc.gov.in, E-mail: pradhans75@gmail.com; Poornima,; Dasgupta, K.

2015-06-15

The operation of a highly sensitive atomic magnetometer using elliptically polarized resonant light is demonstrated. It is based on measurement of zero magnetic field resonance in degenerate two level systems using polarimetric detection. The transmitted light through the polarimeter is used for laser frequency stabilization, whereas reflected light is used for magnetic field measurement. Thus, the experimental geometry allows autonomous frequency stabilization of the laser frequency leading to compact operation of the overall device and has a preliminary sensitivity of <10 pT/Hz{sup 1/2} @ 1 Hz. Additionally, the dynamic range of the device is improved by feedback controlling the biasmore » magnetic field without compromising on its sensitivity.« less

Broadband mid-infrared measurements for shock induced chemistry

NASA Astrophysics Data System (ADS)

McGrane, Shawn; Bowlan, Pamela; Brown, Kathryn; Bolme, Cynthia; Cawkwell, Marc

2017-06-01

Vibrational absorption spectroscopy across the mid-infrared range is a ubiquitous diagnostic of chemical effects due to its sensitivity to small variations in bonding. At the high temperatures and pressures relevant to shock induced chemistry, vibrational spectral peaks become very broad, and accessing as much spectral range as possible with high time resolution can significantly aid in deducing chemical dynamics. Here, we report experiments using broadband (<500 cm-1 to >2000 cm-1) mid-infrared femtosecond supercontinua created by four wave mixing in filaments to perform absorption spectroscopy. These broadband mid-infrared supercontinua are detected through upconversion to visible light. Initial efforts to utilize these methods for measurement of chemical dynamics in shocked nitromethane will be reported.

High speed, wide velocity dynamic range Doppler optical coherence tomography (Part III): in vivo endoscopic imaging of blood flow in the rat and human gastrointestinal tracts

NASA Astrophysics Data System (ADS)

Yang, Victor X. D.; Gordon, Maggie L.; Tang, Shou-Jiang; Marcon, Norman E.; Gardiner, Geoffrey; Qi, Bing; Bisland, Stuart; Seng-Yue, Emily; Lo, Stewart; Pekar, Julius; Wilson, Brian C.; Vitkin, I. Alex

2003-09-01

We previously described a fiber based Doppler optical coherence tomography system [1] capable of imaging embryo cardiac blood flow at 4~16 frames per second with wide velocity dynamic range [2]. Coupling this system to a linear scanning fiber optical catheter design that minimizes friction and vibrations, we report here the initial results of in vivo endoscopic Doppler optical coherence tomography (EDOCT) imaging in normal rat and human esophagus. Microvascular flow in blood vessels less than 100 µm diameter was detected using a combination of color-Doppler and velocity variance imaging modes, during clinical endoscopy using a mobile EDOCT system.

Comparison of salivary collection and processing methods for quantitative HHV-8 detection.

PubMed

Speicher, D J; Johnson, N W

2014-10-01

Saliva is a proved diagnostic fluid for the qualitative detection of infectious agents, but the accuracy of viral load determinations is unknown. Stabilising fluids impede nucleic acid degradation, compared with collection onto ice and then freezing, and we have shown that the DNA Genotek P-021 prototype kit (P-021) can produce high-quality DNA after 14 months of storage at room temperature. Here we evaluate the quantitative capability of 10 collection/processing methods. Unstimulated whole mouth fluid was spiked with a mixture of HHV-8 cloned constructs, 10-fold serial dilutions were produced, and samples were extracted and then examined with quantitative PCR (qPCR). Calibration curves were compared by linear regression and qPCR dynamics. All methods extracted with commercial spin columns produced linear calibration curves with large dynamic range and gave accurate viral loads. Ethanol precipitation of the P-021 does not produce a linear standard curve, and virus is lost in the cell pellet. DNA extractions from the P-021 using commercial spin columns produced linear standard curves with wide dynamic range and excellent limit of detection. When extracted with spin columns, the P-021 enables accurate viral loads down to 23 copies μl(-1) DNA. The quantitative and long-term storage capability of this system makes it ideal for study of salivary DNA viruses in resource-poor settings. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Hardware-in-the-loop projector system for light detection and ranging sensor testing

NASA Astrophysics Data System (ADS)

Kim, Hajin J.; Naumann, Charles B.; Cornell, Michael C.

2012-08-01

Efforts in developing a synthetic environment for testing light detection and ranging (LADAR) sensors in a hardware-in-the-loop simulation are continuing at the Aviation and Missile Research, Engineering, and Development Center of the U.S. Army Research, Engineering and Development Command (RDECOM). Current activities have concentrated on evaluating the optical projection techniques for the LADAR synthetic environment. Schemes for generating the optical signals representing the individual pixels of the projection are of particular interest. Several approaches have been investigated and tested with emphasis on operating wavelength, intensity dynamic range and uniformity, and flexibility in pixel waveform generation. This paper will discuss some of the results from these current efforts at RDECOM's System Simulation and Development Directorate's Electro Optical Technology Development Laboratory.

Age-specific infectious period shapes dynamics of pneumonia in bighorn sheep.

PubMed

Plowright, Raina K; Manlove, Kezia R; Besser, Thomas E; Páez, David J; Andrews, Kimberly R; Matthews, Patrick E; Waits, Lisette P; Hudson, Peter J; Cassirer, E Frances

2017-10-01

Superspreading, the phenomenon where a small proportion of individuals contribute disproportionately to new infections, has profound effects on disease dynamics. Superspreading can arise through variation in contacts, infectiousness or infectious periods. The latter has received little attention, yet it drives the dynamics of many diseases of critical public health, livestock health and conservation concern. Here, we present rare evidence of variation in infectious periods underlying a superspreading phenomenon in a free-ranging wildlife system. We detected persistent infections of Mycoplasma ovipneumoniae, the primary causative agent of pneumonia in bighorn sheep (Ovis canadensis), in a small number of older individuals that were homozygous at an immunologically relevant genetic locus. Interactions among age-structure, genetic composition and infectious periods may drive feedbacks in disease dynamics that determine the magnitude of population response to infection. Accordingly, variation in initial conditions may explain divergent population responses to infection that range from recovery to catastrophic decline and extirpation. © 2017 John Wiley & Sons Ltd/CNRS.

Extended dynamic range of Doppler OCT by application of a new method to high density B-scans using a MHz FDML swept laser source (Conference Presentation)

NASA Astrophysics Data System (ADS)

Elahi, Sahar; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

2017-02-01

The limited dynamic range of optical coherence tomography (OCT) Doppler velocity measurements makes it difficult to conduct experiments on samples requiring a large dynamic range without phase wrapping at high velocities or loss of sensitivity at slow velocities. Hemodynamics and wall motion undergo significant increases in velocity as the embryonic heart develops. Experimental studies indicate that altered hemodynamics in early-stage embryonic hearts can lead to congenital heart diseases (CHDs), motivating close monitoring of blood flow over several stages of development. We have built a high-speed OCT system using an FDML laser (Optores GmbH, Germany) at a sweep rate of 1.68 MHz (axial resolution - 12 μm, sensitivity - 105 dB, phase stability - 17 mrad). The speed of this OCT system allows us to acquire high-density B-scans to obtain an extended velocity dynamic range without sacrificing the frame rate (100 Hz). The extended dynamic range within a frame is achieved by varying the A-scan interval at which the phase difference is found, enabling detection of velocities ranging from tens of microns per second to hundreds of millimeters per second. The extra lines in a frame can also be utilized to improve the structural and Doppler images via complex averaging. In structural images where the presence of blood causes additional scattering, complex averaging helps retrieve features located deeper in the tissue. Moreover, high-density frames can be registered to 4D volumes to determine the orthogonal direction of flow for calculating shear stress as well as estimating the cardiac output. In conclusion, high density B-scans acquired by our high-speed OCT system enable image enhancement and direct measurement of biological parameters in cohort studies.

Highly sensitive detection of target molecules using a new fluorescence-based bead assay

NASA Astrophysics Data System (ADS)

Scheffler, Silvia; Strauß, Denis; Sauer, Markus

2007-07-01

Development of immunoassays with improved sensitivity, specificity and reliability are of major interest in modern bioanalytical research. We describe the development of a new immunomagnetic fluorescence detection (IM-FD) assay based on specific antigen/antibody interactions and on accumulation of the fluorescence signal on superparamagnetic PE beads in combination with the use of extrinsic fluorescent labels. IM-FD can be easily modified by varying the order of coatings and assay conditions. Depending on the target molecule, antibodies (ABs), entire proteins, or small protein epitopes can be used as capture molecules. The presence of target molecules is detected by fluorescence microscopy using fluorescently labeled secondary or detection antibodies. Here, we demonstrate the potential of the new assay detecting the two tumor markers IGF-I and p53 antibodies in the clinically relevant concentration range. Our data show that the fluorescence-based bead assay exhibits a large dynamic range and a high sensitivity down to the subpicomolar level.

Reliability and Validity of Observational Risk Screening in Evaluating Dynamic Knee Valgus

PubMed Central

Ekegren, Christina L.; Miller, William C.; Celebrini, Richard G.; Eng, Janice J.; MacIntyre, Donna L.

2012-01-01

Study Design Nonexperimental methodological study. Objectives To determine the interrater and intrarater reliability and validity of using observational risk screening guidelines to evaluate dynamic knee valgus. Background A deficiency in the neuromuscular control of the hip has been identified as a key risk factor for non-contact anterior cruciate ligament (ACL) injury in post pubescent females. This deficiency can manifest itself as a valgus knee alignment during tasks involving hip and knee flexion. There are currently no scientifically tested methods to screen for dynamic knee valgus in the clinic or on the field. Methods Three physiotherapists used observational risk screening guidelines to rate 40 adolescent female soccer players according to their risk of ACL injury. The rating was based on the amount of dynamic knee valgus observed on a drop jump landing. Ratings were evaluated for intrarater and interrater agreement using kappa coefficients. Sensitivity and specificity of ratings were evaluated by comparing observational ratings with measurements obtained using 3-dimensional (3D) motion analysis. Results Kappa coefficients for intrarater and interrater agreement ranged from 0.75 to 0.85, indicating that ratings were reasonably consistent over time and between physiotherapists. Sensitivity values were inadequate, ranging from 67–87%. This indicated that raters failed to detect up to a third of “truly high risk” individuals. Specificity values ranged from 60–72% which was considered adequate for the purposes of the screen. Conclusion Observational risk screening is a practical and cost-effective method of screening for ACL injury risk. Rater agreement and specificity were acceptable for this method but sensitivity was not. To detect a greater proportion of individuals at risk of ACL injury, coaches and clinicians should ensure that they include additional tests for other high risk characteristics in their screening protocols. PMID:19721212

[Analytical method and comparison for static and dynamic headspace gas chromatography of anisole in water].

PubMed

Zhang, Yan; Qian, Jie-feng; Liu, Lan-xia; Zhao, Hui-qin

2013-01-01

To establish and compare the method of static headspace gas chromatography hydrogen flame detector (static headspace method) and purge and trap gas chromatography-mass spectrometry (dynamic headspace method) of anisole in water. Nitrogen gas was used as carrier gas in the static headspace method, 5 g NaCl as matrix modifier was added into 10 ml water. The sample was balanced with high speed vibration at 75°C for 30 min, and anisole was detected by gas chromatography and quantified with external standard. Helium was used as carrier gas in dynamic headspace method, 5.0 ml water and 0.004 mg/L internal standard fluorobenzene was purged into the purge and trap apparatus. After purging, trapping and desorption, anisole was detected by the gas chromatography-mass spectrograph, confirmed by the retention time and comparison of mass-spectrogram in spectrum library and quantified with internal standard. The repeatability and sensitivity of assay were evaluated. A good linear range for anisole was observed in static headspace gas chromatography and dynamic headspace gas chromatography-mass spectrometry, within the range of 10 - 500 µg/L and 0.5 - 60.0 µg/L respectively. The linear regression equation was Y = 782.150X + 1.3446 and Y = 0.0358X - 0.0209 respectively, both the correlation coefficient ≥ 0.999. The detection limit (LOD) were 0.002 µg/L and 0.110 µg/L, the lower limit of quantitation (LOQ) were 0.006 µg/L and 0.350 µg/L, the relative standard deviation (RSD) were 1.8% - 2.3% and 2.0% - 3.4%, and the spiking recovery were 93% - 101% and 96% - 101% respectively. The methods of static headspace gas chromatography and dynamic headspace gas chromatography-mass spectrometry are simple and can measure anisole in water quickly, sensitively and accurately.

Potential and limitations of satellite laser altimetry for monitoring water surface dynamics: ICESat for US lakes

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

Shu, Liu; Qigang, Jiang; Zhang, Xuesong

Elevation measurements from the Ice, Cloud and Land Elevation Satellite (ICESat) have been applied to monitor dynamics of lakes and other surface water bodies. Despite such potential, the true utility of ICESat--more generally, satellite laser altimetry--for tracking surface water dynamics over time has not been adequately assessed, especially in the continental or global contexts. Here, we analyzed ICESat elevation data for the conterminous United States and examined the potential and limitations of satellite laser altimetry in measuring water-level dynamics. Owing to a lack of spatially-explicit ground-based water-level data, we first resorted to high-fidelity land elevation data acquired by airborne lidarmore » to quantify ICESat’s ranging accuracy. We then performed trend and frequency analyses to evaluate how reliably ICESat could capture water-level dynamics over a range of temporal scales, as compared to in-situ gauge measurements. Our analyses showed that ICESat had a vertical ranging error of 0.16 m at the footprint level—a limit on the detectable range of water-level dynamics. The sparsity of data over time was identified as a major factor limiting the use of ICESat for water dynamics studies. Of all the US lakes, only 361 had quality ICESat measurements for more than two flight passes. Even for those lakes with sufficient temporal coverage, ICESat failed to capture the true interannual water-level dynamics in 68% of the cases. Our frequency analysis suggested that even with a repeat cycle of two months, ICESat could capture only 60% of the variations in water-level dynamics for at most 34 % of the US lakes. To capture 60% of the water-level variation for most of the US lakes, a weekly repeat cycle (e.g., less than 5 days) is needed – a requirement difficult to meet in current designs of spaceborne laser altimetry. Overall, our results highlight that current or near-future satellite laser missions, though with high ranging accuracies, are unlikely to fulfill the general needs in remotely monitoring water surface dynamics for lakes or reservoirs.« less

New maxillofacial infrared detection technologies

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

Reshetnikov, A. P.; Kopylov, M. V.; Nasyrov, M. R., E-mail: marat.1994@me.com

At the dental clinic the infrared range radiation spectrum of tissues was used to study the dynamics of local temperature and structure of the skin, subcutaneous fat, and other tissues of the maxillofacial area in adult healthy volunteers and patients. In particular, we studied the dynamics of local temperature of mucous membranes of the mouth, teeth, and places in the mouth and dental structures in the norm and in various pathological conditions of the lips, gums, teeth, tongue, palate, and cheeks before, during and after chewing food, drinking water, medication, and inhalation of air. High safety and informational content ofmore » infrared thermography are prospective for the development of diagnostics in medicine. We have 3 new methods for infrared detection protected by patents in Russia.« less

Autonomous control of roving vehicles for unmanned exploration of the planets

NASA Technical Reports Server (NTRS)

Yerazunis, S. W.

1978-01-01

The guidance of an autonomous rover for unmanned planetary exploration using a short range (0.5 - 3.0 meter) hazard detection system was studied. Experimental data derived from a one laser/one detector system were used in the development of improved algorithms for the guidance of the rover. The new algorithms which account for the dynamic characteristics of the Rensselaer rover can be applied to other rover concepts provided that the rover dynamic parameters are modified appropriately. The new algorithms will also be applicable to the advanced scanning system. The design of an elevation scanning laser/multisensor hazard detection system was completed. All mechanical and electronic hardware components with the exception of the sensor optics and electronic components were constructed and tested.

New maxillofacial infrared detection technologies

NASA Astrophysics Data System (ADS)

Reshetnikov, A. P.; Kopylov, M. V.; Nasyrov, M. R.; Soicher, E. M.; Fisher, E. L.; Chernova, L. V.

2015-11-01

At the dental clinic the infrared range radiation spectrum of tissues was used to study the dynamics of local temperature and structure of the skin, subcutaneous fat, and other tissues of the maxillofacial area in adult healthy volunteers and patients. In particular, we studied the dynamics of local temperature of mucous membranes of the mouth, teeth, and places in the mouth and dental structures in the norm and in various pathological conditions of the lips, gums, teeth, tongue, palate, and cheeks before, during and after chewing food, drinking water, medication, and inhalation of air. High safety and informational content of infrared thermography are prospective for the development of diagnostics in medicine. We have 3 new methods for infrared detection protected by patents in Russia.

Can you hear me now? Range-testing a submerged passive acoustic receiver array in a Caribbean coral reef habitat

USGS Publications Warehouse

Selby, Thomas H.; Hart, Kristen M.; Fujisaki, Ikuko; Smith, Brian J.; Pollock, Clayton J; Hillis-Star, Zandy M; Lundgren, Ian; Oli, Madan K.

2016-01-01

Submerged passive acoustic technology allows researchers to investigate spatial and temporal movement patterns of many marine and freshwater species. The technology uses receivers to detect and record acoustic transmissions emitted from tags attached to an individual. Acoustic signal strength naturally attenuates over distance, but numerous environmental variables also affect the probability a tag is detected. Knowledge of receiver range is crucial for designing acoustic arrays and analyzing telemetry data. Here, we present a method for testing a relatively large-scale receiver array in a dynamic Caribbean coastal environment intended for long-term monitoring of multiple species. The U.S. Geological Survey and several academic institutions in collaboration with resource management at Buck Island Reef National Monument (BIRNM), off the coast of St. Croix, recently deployed a 52 passive acoustic receiver array. We targeted 19 array-representative receivers for range-testing by submersing fixed delay interval range-testing tags at various distance intervals in each cardinal direction from a receiver for a minimum of an hour. Using a generalized linear mixed model (GLMM), we estimated the probability of detection across the array and assessed the effect of water depth, habitat, wind, temperature, and time of day on the probability of detection. The predicted probability of detection across the entire array at 100 m distance from a receiver was 58.2% (95% CI: 44.0–73.0%) and dropped to 26.0% (95% CI: 11.4–39.3%) 200 m from a receiver indicating a somewhat constrained effective detection range. Detection probability varied across habitat classes with the greatest effective detection range occurring in homogenous sand substrate and the smallest in high rugosity reef. Predicted probability of detection across BIRNM highlights potential gaps in coverage using the current array as well as limitations of passive acoustic technology within a complex coral reef environment.

An algorithm to correct saturated mass spectrometry ion abundances for enhanced quantitation and mass accuracy in omic studies

DOE PAGES

Bilbao, Aivett; Gibbons, Bryson C.; Slysz, Gordon W.; ...

2017-11-06

We present that the mass accuracy and peak intensity of ions detected by mass spectrometry (MS) measurements are essential to facilitate compound identification and quantitation. However, high concentration species can yield erroneous results if their ion intensities reach beyond the limits of the detection system, leading to distorted and non-ideal detector response (e.g. saturation), and largely precluding the calculation of accurate m/z and intensity values. Here we present an open source computational method to correct peaks above a defined intensity (saturated) threshold determined by the MS instrumentation such as the analog-to-digital converters or time-to-digital converters used in conjunction with time-of-flightmore » MS. Here, in this method, the isotopic envelope for each observed ion above the saturation threshold is compared to its expected theoretical isotopic distribution. The most intense isotopic peak for which saturation does not occur is then utilized to re-calculate the precursor m/z and correct the intensity, resulting in both higher mass accuracy and greater dynamic range. The benefits of this approach were evaluated with proteomic and lipidomic datasets of varying complexities. After correcting the high concentration species, reduced mass errors and enhanced dynamic range were observed for both simple and complex omic samples. Specifically, the mass error dropped by more than 50% in most cases for highly saturated species and dynamic range increased by 1–2 orders of magnitude for peptides in a blood serum sample.« less

An algorithm to correct saturated mass spectrometry ion abundances for enhanced quantitation and mass accuracy in omic studies

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

Bilbao, Aivett; Gibbons, Bryson C.; Slysz, Gordon W.

The mass accuracy and peak intensity of ions detected by mass spectrometry (MS) measurements are essential to facilitate compound identification and quantitation. However, high concentration species can easily cause problems if their ion intensities reach beyond the limits of the detection system, leading to distorted and non-ideal detector response (e.g. saturation), and largely precluding the calculation of accurate m/z and intensity values. Here we present an open source computational method to correct peaks above a defined intensity (saturated) threshold determined by the MS instrumentation such as the analog-to-digital converters or time-to-digital converters used in conjunction with time-of-flight MS. In thismore » method, the isotopic envelope for each observed ion above the saturation threshold is compared to its expected theoretical isotopic distribution. The most intense isotopic peak for which saturation does not occur is then utilized to re-calculate the precursor m/z and correct the intensity, resulting in both higher mass accuracy and greater dynamic range. The benefits of this approach were evaluated with proteomic and lipidomic datasets of varying complexities. After correcting the high concentration species, reduced mass errors and enhanced dynamic range were observed for both simple and complex omic samples. Specifically, the mass error dropped by more than 50% in most cases with highly saturated species and dynamic range increased by 1-2 orders of magnitude for peptides in a blood serum sample.« less

An algorithm to correct saturated mass spectrometry ion abundances for enhanced quantitation and mass accuracy in omic studies

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

Bilbao, Aivett; Gibbons, Bryson C.; Slysz, Gordon W.

We present that the mass accuracy and peak intensity of ions detected by mass spectrometry (MS) measurements are essential to facilitate compound identification and quantitation. However, high concentration species can yield erroneous results if their ion intensities reach beyond the limits of the detection system, leading to distorted and non-ideal detector response (e.g. saturation), and largely precluding the calculation of accurate m/z and intensity values. Here we present an open source computational method to correct peaks above a defined intensity (saturated) threshold determined by the MS instrumentation such as the analog-to-digital converters or time-to-digital converters used in conjunction with time-of-flightmore » MS. Here, in this method, the isotopic envelope for each observed ion above the saturation threshold is compared to its expected theoretical isotopic distribution. The most intense isotopic peak for which saturation does not occur is then utilized to re-calculate the precursor m/z and correct the intensity, resulting in both higher mass accuracy and greater dynamic range. The benefits of this approach were evaluated with proteomic and lipidomic datasets of varying complexities. After correcting the high concentration species, reduced mass errors and enhanced dynamic range were observed for both simple and complex omic samples. Specifically, the mass error dropped by more than 50% in most cases for highly saturated species and dynamic range increased by 1–2 orders of magnitude for peptides in a blood serum sample.« less

Polyaniline-based optical ammonia detector

DOEpatents

Duan, Yixiang; Jin, Zhe; Su, Yongxuan

2002-01-01

Electronic absorption spectroscopy of a polyaniline film deposited on a polyethylene surface by chemical oxidation of aniline monomer at room temperature was used to quantitatively detect ammonia gas. The present optical ammonia gas detector was found to have a response time of less than 15 s, a regeneration time of less than 2 min. at room temperature, and a detection limit of 1 ppm (v/v) for ammonia, with a linear dynamic range from 180 ppm to 18,000 ppm.

75 FR 82372 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-30

..., Argonne LLC, 9700 South Cass Ave., Lemont, IL 60439. Instrument: Pilatus 100K Pixel Detector System... efficiency (no readout noise and direct detection scheme), high dynamic range (20-bits), and fast readout.... Instrument: Pilatus 300K Pixel Detector System. Manufacturer: Dectris Ltd., Switzerland. Intended Use: The...

Quantitative mass imaging of single biological macromolecules.

PubMed

Young, Gavin; Hundt, Nikolas; Cole, Daniel; Fineberg, Adam; Andrecka, Joanna; Tyler, Andrew; Olerinyova, Anna; Ansari, Ayla; Marklund, Erik G; Collier, Miranda P; Chandler, Shane A; Tkachenko, Olga; Allen, Joel; Crispin, Max; Billington, Neil; Takagi, Yasuharu; Sellers, James R; Eichmann, Cédric; Selenko, Philipp; Frey, Lukas; Riek, Roland; Galpin, Martin R; Struwe, Weston B; Benesch, Justin L P; Kukura, Philipp

2018-04-27

The cellular processes underpinning life are orchestrated by proteins and their interactions. The associated structural and dynamic heterogeneity, despite being key to function, poses a fundamental challenge to existing analytical and structural methodologies. We used interferometric scattering microscopy to quantify the mass of single biomolecules in solution with 2% sequence mass accuracy, up to 19-kilodalton resolution, and 1-kilodalton precision. We resolved oligomeric distributions at high dynamic range, detected small-molecule binding, and mass-imaged proteins with associated lipids and sugars. These capabilities enabled us to characterize the molecular dynamics of processes as diverse as glycoprotein cross-linking, amyloidogenic protein aggregation, and actin polymerization. Interferometric scattering mass spectrometry allows spatiotemporally resolved measurement of a broad range of biomolecular interactions, one molecule at a time. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Advanced optical fiber communication systems

NASA Astrophysics Data System (ADS)

Kazovsky, Leonid G.

1994-03-01

Our research is focused on three major aspects of advanced optical fiber communication systems: dynamic wavelength division multiplexing (WDM) networks, fiber nonlinearities, and high dynamic range coherent analog optical links. In the area of WDM networks, we have designed and implemented two high-speed interface boards and measured their throughput and latency. Furthermore, we designed and constructed an experimental PSK/ASK transceiver that simultaneously transmits packet-switched ASK data and circuit-switched PSK data on the same optical carrier. In the area of fiber nonlinearities, we investigated the theoretical impact of modulation frequency on cross-phase modulation (XPM) in dispersive fibers. In the area of high dynamic range coherent analog optical links, we developed theoretical expressions for the RF power transfer ratio (or RF power gain) and the noise figure (NF) of angle-modulated links. We then compared the RF power gains and noise figures of these links to that of an intensity modulated direct detection (DD) link.

Multi-GNSS high-rate RTK, PPP and novel direct phase observation processing method: application to precise dynamic displacement detection

NASA Astrophysics Data System (ADS)

Paziewski, Jacek; Sieradzki, Rafal; Baryla, Radoslaw

2018-03-01

This paper provides the methodology and performance assessment of multi-GNSS signal processing for the detection of small-scale high-rate dynamic displacements. For this purpose, we used methods of relative (RTK) and absolute positioning (PPP), and a novel direct signal processing approach. The first two methods are recognized as providing accurate information on position in many navigation and surveying applications. The latter is an innovative method for dynamic displacement determination with the use of GNSS phase signal processing. This method is based on the developed functional model with parametrized epoch-wise topocentric relative coordinates derived from filtered GNSS observations. Current regular kinematic PPP positioning, as well as medium/long range RTK, may not offer coordinate estimates with subcentimeter precision. Thus, extended processing strategies of absolute and relative GNSS positioning have been developed and applied for displacement detection. The study also aimed to comparatively analyze the developed methods as well as to analyze the impact of combined GPS and BDS processing and the dependence of the results of the relative methods on the baseline length. All the methods were implemented with in-house developed software allowing for high-rate precise GNSS positioning and signal processing. The phase and pseudorange observations collected with a rate of 50 Hz during the field test served as the experiment’s data set. The displacements at the rover station were triggered in the horizontal plane using a device which was designed and constructed to ensure a periodic motion of GNSS antenna with an amplitude of ~3 cm and a frequency of ~4.5 Hz. Finally, a medium range RTK, PPP, and direct phase observation processing method demonstrated the capability of providing reliable and consistent results with the precision of the determined dynamic displacements at the millimeter level. Specifically, the research shows that the standard deviation of the displacement residuals obtained as the difference between a benchmark-ultra-short baseline RTK solution and selected scenarios ranged between 1.1 and 3.4 mm. At the same time, the differences in the mean amplitude of the oscillations derived from the established scenarios did not exceed 1.3 mm, whereas the frequency of the motion detected with the use of Fourier transformation was the same.

Wireless infrared computer control

NASA Astrophysics Data System (ADS)

Chen, George C.; He, Xiaofei

2004-04-01

Wireless mouse is not restricted by cable"s length and has advantage over its wired counterpart. However, all the mice available in the market have detection range less than 2 meters and angular coverage less than 180 degrees. Furthermore, commercial infrared mice are based on track ball and rollers to detect movements. This restricts them to be used in those occasions where users want to have dynamic movement, such as presentations and meetings etc. This paper presents our newly developed infrared wireless mouse, which has a detection range of 6 meters and angular coverage of 180 degrees. This new mouse uses buttons instead of traditional track ball and is developed to be a hand-held device like remote controller. It enables users to control cursor with a distance closed to computer and the mouse to be free from computer operation.

On the phenomenon of mixed dynamics in Pikovsky-Topaj system of coupled rotators

NASA Astrophysics Data System (ADS)

Gonchenko, A. S.; Gonchenko, S. V.; Kazakov, A. O.; Turaev, D. V.

2017-07-01

A one-parameter family of time-reversible systems on three-dimensional torus is considered. It is shown that the dynamics is not conservative, namely the attractor and repeller intersect but not coincide. We explain this as the manifestation of the so-called mixed dynamics phenomenon which corresponds to a persistent intersection of the closure of the stable periodic orbits and the closure of the completely unstable periodic orbits. We search for the stable and unstable periodic orbits indirectly, by finding non-conservative saddle periodic orbits and heteroclinic connections between them. In this way, we are able to claim the existence of mixed dynamics for a large range of parameter values. We investigate local and global bifurcations that can be used for the detection of mixed dynamics.

Wide-spectral/dynamic-range skin-compatible phototransistors enabled by floated heterojunction structures with surface functionalized SWCNTs and amorphous oxide semiconductors.

PubMed

Hwang, Insik; Kim, Jaehyun; Lee, Minkyung; Lee, Min-Wook; Kim, Hee-Joong; Kwon, Hyuck-In; Hwang, Do Kyung; Kim, Myunggil; Yoon, Haeyoung; Kim, Yong-Hoon; Park, Sung Kyu

2017-11-09

Purified semiconducting single-walled carbon nanotubes (sc-SWCNTs) have been researched for optoelectronic applications due to their high absorption coefficient from the visible to even the near-infrared (NIR) region. Nevertheless, the insufficient electrical characteristics and incompatibility with conventional CMOS processing have limited their wide utilization in this emerging field. Here, we demonstrate highly detective and wide spectral/dynamic range phototransistors incorporating floated heterojunction active layers which are composed of low-temperature sol-gel processed n-type amorphous indium gallium zinc oxide (a-IGZO) stacked with a purified p-type sc-SWCNT layer. To achieve a high and broad spectral/dynamic range photo-response of the heterogeneous transistors, photochemically functionalized sc-SWCNT layers were carefully implemented onto the a-IGZO channel area with a floating p-n heterojunction active layer, resulting in the suppression of parasitic charge leakage and good bias driven opto-electrical properties. The highest photosensitivity (R) of 9.6 × 10 2 A W -1 and a photodetectivity (D*) of 4 × 10 14 Jones along with a dynamic range of 100-180 dB were achieved for our phototransistor in the spectral range of 400-780 nm including continuous and minimal frequency independent behaviors. More importantly, to demonstrate the diverse application of the ultra-flexible hybrid photosensor platform as skin compatible electronics, the sc-SWCNT/a-IGZO phototransistors were fabricated on an ultra-thin (∼1 μm) polyimide film along with a severe static and dynamic electro-mechanical test. The skin-like phototransistors showed excellent mechanical stability such as sustainable good electrical performance and high photosensitivity in a wide dynamic range without any visible cracks or damage and little noise interference after being rolled-up on the 150 μm-thick optical fiber as well as more than 1000 times cycling.

When and where to move: Dynamic occupancy models explain the range dynamics of a food nomadic bird under climate and land cover change.

PubMed

Kalle, Riddhika; Ramesh, Tharmalingam; Downs, Colleen T

2018-01-01

Globally, long-term research is critical to monitor the responses of tropical species to climate and land cover change at the range scale. Citizen science surveys can reveal the long-term persistence of poorly known nomadic tropical birds occupying fragmented forest patches. We applied dynamic occupancy models to 13 years (2002-2014) of citizen science-driven presence/absence data on Cape parrot (Poicephalus robustus), a food nomadic bird endemic to South Africa. We modeled its underlying range dynamics as a function of resource distribution, and change in climate and land cover through the estimation of colonization and extinction patterns. The range occupancy of Cape parrot changed little over time (ψ = 0.75-0.83) because extinction was balanced by recolonization. Yet, there was considerable regional variability in occupancy and detection probability increased over the years. Colonizations increased with warmer temperature and area of orchards, thus explaining their range shifts southeastwards in recent years. Although colonizations were higher in the presence of nests and yellowwood trees (Afrocarpus and Podocarpus spp.), the extinctions in small forest patches (≤227 ha) and during low precipitation (≤41 mm) are attributed to resource constraints and unsuitable climatic conditions. Loss of indigenous forest cover and artificial lake/water bodies increased extinction probabilities of Cape parrot. The land use matrix (fruit farms, gardens, and cultivations) surrounding forest patches provides alternative food sources, thereby facilitating spatiotemporal colonization and extinction in the human-modified matrix. Our models show that Cape parrots are vulnerable to extreme climatic conditions such as drought which is predicted to increase under climate change. Therefore, management of optimum sized high-quality forest patches is essential for long-term survival of Cape parrot populations. Our novel application of dynamic occupancy models to long-term citizen science monitoring data unfolds the complex relationships between the environmental dynamics and range fluctuations of this food nomadic species. © 2017 John Wiley & Sons Ltd.

Extraction and preconcentration of residual solvents in pharmaceuticals using dynamic headspace-liquid phase microextraction and their determination by gas chromatography-flame ionization detection.

PubMed

Farajzadeh, Mir Ali; Dehghani, Hamideh; Yadeghari, Adeleh; Khoshmaram, Leila

2017-02-01

The present study describes a microextraction and determination method for analyzing residual solvents in pharmaceutical products using dynamic headspace-liquid phase microextraction technique followed by gas chromatography-flame ionization detection. In this method dimethyl sulfoxide (μL level) placed into a GC liner-shaped extraction vessel is used as a collection/extraction solvent. Then the liner is exposed to the headspace of a vial containing the sample solution. The effect of different parameters influencing the microextraction procedure including collection/extraction solvent type and its volume, ionic strength, extraction time, extraction temperature and concentration of NaOH solution used in dissolving the studied pharmaceuticals are investigated and optimized. Under the optimum extraction conditions, the method showed wide linear ranges between 0.5 and 5000 mg L -1 . The other analytical parameters were obtained in the following ranges: enrichment factors 240-327, extraction recoveries 72-98% and limits of detection 0.1-0.8 mg L -1 in solution and 0.6-3.2 μg g -1 in solid. Relative standard deviations for the extraction of 100 mg L -1 of each analyte were obtained in the ranges of 4-7 and 5-8% for intra-day (n = 6) and inter-day (n = 4) respectively. Finally the target analytes were determined in different samples such as erythromycin, azithromycin, cefalexin, amoxicillin and co-amoxiclav by the proposed method. Copyright © 2016 John Wiley & Sons, Ltd.

Impact of respiratory motion correction and spatial resolution on lesion detection in PET: a simulation study based on real MR dynamic data

NASA Astrophysics Data System (ADS)

Polycarpou, Irene; Tsoumpas, Charalampos; King, Andrew P.; Marsden, Paul K.

2014-02-01

The aim of this study is to investigate the impact of respiratory motion correction and spatial resolution on lesion detectability in PET as a function of lesion size and tracer uptake. Real respiratory signals describing different breathing types are combined with a motion model formed from real dynamic MR data to simulate multiple dynamic PET datasets acquired from a continuously moving subject. Lung and liver lesions were simulated with diameters ranging from 6 to 12 mm and lesion to background ratio ranging from 3:1 to 6:1. Projection data for 6 and 3 mm PET scanner resolution were generated using analytic simulations and reconstructed without and with motion correction. Motion correction was achieved using motion compensated image reconstruction. The detectability performance was quantified by a receiver operating characteristic (ROC) analysis obtained using a channelized Hotelling observer and the area under the ROC curve (AUC) was calculated as the figure of merit. The results indicate that respiratory motion limits the detectability of lung and liver lesions, depending on the variation of the breathing cycle length and amplitude. Patients with large quiescent periods had a greater AUC than patients with regular breathing cycles and patients with long-term variability in respiratory cycle or higher motion amplitude. In addition, small (less than 10 mm diameter) or low contrast (3:1) lesions showed the greatest improvement in AUC as a result of applying motion correction. In particular, after applying motion correction the AUC is improved by up to 42% with current PET resolution (i.e. 6 mm) and up to 51% for higher PET resolution (i.e. 3 mm). Finally, the benefit of increasing the scanner resolution is small unless motion correction is applied. This investigation indicates high impact of respiratory motion correction on lesion detectability in PET and highlights the importance of motion correction in order to benefit from the increased resolution of future PET scanners.

Rapid-scan Fourier-transform coherent anti-Stokes Raman scattering spectroscopy with heterodyne detection.

PubMed

Hiramatsu, Kotaro; Luo, Yizhi; Ideguchi, Takuro; Goda, Keisuke

2017-11-01

High-speed Raman spectroscopy has become increasingly important for analyzing chemical dynamics in real time. To address the need, rapid-scan Fourier-transform coherent anti-Stokes Raman scattering (FT-CARS) spectroscopy has been developed to realize broadband CARS measurements at a scan rate of more than 20,000 scans/s. However, the detection sensitivity of FT-CARS spectroscopy is inherently low due to the limited number of photons detected during each scan. In this Letter, we show our experimental demonstration of enhanced sensitivity in rapid-scan FT-CARS spectroscopy by heterodyne detection. Specifically, we implemented heterodyne detection by superposing the CARS electric field with an external local oscillator (LO) for their interference. The CARS signal was amplified by simply increasing the power of the LO without the need for increasing the incident power onto the sample. Consequently, we achieved enhancement in signal intensity and the signal-to-noise ratio by factors of 39 and 5, respectively, compared to FT-CARS spectroscopy with homodyne detection. The sensitivity-improved rapid-scan FT-CARS spectroscopy is expected to enable the sensitive real-time observation of chemical dynamics in a broad range of settings, such as combustion engines and live biological cells.

Comparisons between detection threshold and loudness perception for individual cochlear implant channels

PubMed Central

Bierer, Julie Arenberg; Nye, Amberly D

2014-01-01

Objective The objective of the present study, performed in cochlear implant listeners, was to examine how the level of current required to detect single-channel electrical pulse trains relates to loudness perception on the same channel. The working hypothesis was that channels with relatively high thresholds, when measured with a focused current pattern, interface poorly to the auditory nerve. For such channels a smaller dynamic range between perceptual threshold and the most comfortable loudness would result, in part, from a greater sensitivity to changes in electrical field spread compared to low-threshold channels. The narrower range of comfortable listening levels may have important implications for speech perception. Design Data were collected from eight, adult cochlear implant listeners implanted with the HiRes90k cochlear implant (Advanced Bionics Corp.). The partial tripolar (pTP) electrode configuration, consisting of one intracochlear active electrode, two flanking electrodes carrying a fraction (σ) of the return current, and an extracochlear ground, was used for stimulation. Single-channel detection thresholds and most comfortable listening levels were acquired using the most focused pTP configuration possible (σ ≥ 0.8) to identify three channels for further testing – those with the highest, median, and lowest thresholds – for each subject. Threshold, equal-loudness contours (at 50% of the monopolar dynamic range), and loudness growth functions were measured for each of these three test channels using various partial tripolar fractions. Results For all test channels, thresholds increased as the electrode configuration became more focused. The rate of increase with the focusing parameter σ was greatest for the high-threshold channel compared to the median- and low-threshold channels. The 50% equal-loudness contours exhibited similar rates of increase in level across test channels and subjects. Additionally, test channels with the highest thresholds had the narrowest dynamic ranges (for σ ≥ 0.5) and steepest growth of loudness functions for all electrode configurations. Conclusions Together with previous studies using focused stimulation, the results suggest that auditory responses to electrical stimuli at both threshold and suprathreshold current levels are not uniform across the electrode array of individual cochlear implant listeners. Specifically, the steeper growth of loudness and thus smaller dynamic ranges observed for high-threshold channels are consistent with a degraded electrode-neuron interface, which could stem from lower numbers of functioning auditory neurons or a relatively large distance between the neurons and electrodes. These findings may have potential implications for how stimulation levels are set during the clinical mapping procedure, particularly for speech-processing strategies that use focused electrical fields. PMID:25036146

Demodulation System for Fiber Optic Bragg Grating Dynamic Pressure Sensing

NASA Technical Reports Server (NTRS)

Lekki, John D.; Adamovsky, Grigory; Floyd, Bertram

2001-01-01

Fiber optic Bragg gratings have been used for years to measure quasi-static phenomena. In aircraft engine applications there is a need to measure dynamic signals such as variable pressures. In order to monitor these pressures a detection system with broad dynamic range is needed. This paper describes an interferometric demodulator that was developed and optimized for this particular application. The signal to noise ratio was maximized through temporal coherence analysis. The demodulator was incorporated in a laboratory system that simulates conditions to be measured. Several pressure sensor configurations incorporating a fiber optic Bragg grating were also explored. The results of the experiments are reported in this paper.

Direct Duplex Detection: An Emerging Tool in the RNA Structure Analysis Toolbox.

PubMed

Weidmann, Chase A; Mustoe, Anthony M; Weeks, Kevin M

2016-09-01

While a variety of powerful tools exists for analyzing RNA structure, identifying long-range and intermolecular base-pairing interactions has remained challenging. Recently, three groups introduced a high-throughput strategy that uses psoralen-mediated crosslinking to directly identify RNA-RNA duplexes in cells. Initial application of these methods highlights the preponderance of long-range structures within and between RNA molecules and their widespread structural dynamics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamic time-correlated single-photon counting laser ranging

NASA Astrophysics Data System (ADS)

Peng, Huan; Wang, Yu-rong; Meng, Wen-dong; Yan, Pei-qin; Li, Zhao-hui; Li, Chen; Pan, Hai-feng; Wu, Guang

2018-03-01

We demonstrate a photon counting laser ranging experiment with a four-channel single-photon detector (SPD). The multi-channel SPD improve the counting rate more than 4×107 cps, which makes possible for the distance measurement performed even in daylight. However, the time-correlated single-photon counting (TCSPC) technique cannot distill the signal easily while the fast moving targets are submersed in the strong background. We propose a dynamic TCSPC method for fast moving targets measurement by varying coincidence window in real time. In the experiment, we prove that targets with velocity of 5 km/s can be detected according to the method, while the echo rate is 20% with the background counts of more than 1.2×107 cps.

2.75 THz tuning with a triple-DFB laser system at 1550 nm and InGaAs photomixers

NASA Astrophysics Data System (ADS)

Deninger, Anselm J.; Roggenbuck, A.; Schindler, S.; Preu, S.

2015-03-01

To date, exploiting the full bandwidth of state-of-the-art InGaAs photomixers for generation and detection of continuous-wave (CW) THz radiation (typ. ~50 GHz to ~3 THz) required complex and costly external-cavity diode lasers with motorized resonator control. Distributed feedback (DFB) lasers, by contrast, are compact and inexpensive, but the tuning range per diode is limited to ~600 GHz at 1.5 μm. In this paper, we show that a combination of three DFB diodes covers the complete frequency range from 0 - 2750 GHz without any gaps. In combination with InGaAs-based photomixers for terahertz generation and detection, the system achieves a dynamic range of > 100 dB at 56 GHz, 64 dB at 1000 GHz, and 26 dB at 2500 GHz. A field-programmable gate array (FPGA)-based lock-in amplifier permits a flexible adjustment of the integration time from 0.5 ms to 600 ms. Employing an optimized "fast scan" mode, a spectrum of ~1200 GHz - the bandwidth of each subset of two lasers - and 40 MHz steps is acquired in less than one minute, still maintaining a reasonable dynamic range. To the best of our knowledge, the bandwidth of 2.75 THz presents a new record for DFB-based CW-terahertz systems.

Shack-Hartmann wavefront sensor with large dynamic range.

PubMed

Xia, Mingliang; Li, Chao; Hu, Lifa; Cao, Zhaoliang; Mu, Quanquan; Xuan, Li

2010-01-01

A new spot centroid detection algorithm for a Shack-Hartmann wavefront sensor (SHWFS) is experimentally investigated. The algorithm is a kind of dynamic tracking algorithm that tracks and calculates the corresponding spot centroid of the current spot map based on the spot centroid of the previous spot map, according to the strong correlation of the wavefront slope and the centroid of the corresponding spot between temporally adjacent SHWFS measurements. That is, for adjacent measurements, the spot centroid movement will usually fall within some range. Using the algorithm, the dynamic range of an SHWFS can be expanded by a factor of three in the measurement of tilt aberration compared with the conventional algorithm, more than 1.3 times in the measurement of defocus aberration, and more than 2 times in the measurement of the mixture of spherical aberration plus coma aberration. The algorithm is applied in our SHWFS to measure the distorted wavefront of the human eye. The experimental results of the adaptive optics (AO) system for retina imaging are presented to prove its feasibility for highly aberrated eyes.

Perceptual Contrast Enhancement with Dynamic Range Adjustment

PubMed Central

Zhang, Hong; Li, Yuecheng; Chen, Hao; Yuan, Ding; Sun, Mingui

2013-01-01

Recent years, although great efforts have been made to improve its performance, few Histogram equalization (HE) methods take human visual perception (HVP) into account explicitly. The human visual system (HVS) is more sensitive to edges than brightness. This paper proposes to take use of this nature intuitively and develops a perceptual contrast enhancement approach with dynamic range adjustment through histogram modification. The use of perceptual contrast connects the image enhancement problem with the HVS. To pre-condition the input image before the HE procedure is implemented, a perceptual contrast map (PCM) is constructed based on the modified Difference of Gaussian (DOG) algorithm. As a result, the contrast of the image is sharpened and high frequency noise is suppressed. A modified Clipped Histogram Equalization (CHE) is also developed which improves visual quality by automatically detecting the dynamic range of the image with improved perceptual contrast. Experimental results show that the new HE algorithm outperforms several state-of-the-art algorithms in improving perceptual contrast and enhancing details. In addition, the new algorithm is simple to implement, making it suitable for real-time applications. PMID:24339452

Hybrid Ion-Detector/Data-Acquisition System for a TOF-MS

NASA Technical Reports Server (NTRS)

Burton, William D., Jr.; Schultz, J. Albert; Vaughn, Valentine; McCully, Michael; Ulrich, Steven; Egan, Thomas F.

2006-01-01

A modified ion-detector/data-acquisition system has been devised to increase the dynamic range of a time-of-flight mass spectrometer (TOF-MS) that, previously, included a microchannel-plate detector and a data-acquisition system based on counting pulses and time-tagging them by use of a time-to-digital converter (TDC). The dynamic range of the TOF-MS was limited by saturation of the microchannel plate detector, which can handle no more than a few million counts per second. The modified system includes (1) a combined microchannel plate/discrete ion multiplier and (2) a hybrid data-acquisition system that simultaneously performs analog current or voltage measurements and multianode single-ion-pulse-counting time-of-flight measurements to extend the dynamic range of a TDC into the regime in which a mass peak comprises multiple ions arriving simultaneously at the detector. The multianode data are used to determine, in real time, whether the detector is saturated. When saturation is detected, the data-acquisition system selectively enables circuitry that simultaneously determines the ion-peak intensity by measuring the time profile of the analog current or voltage detector-output signal.

Large dynamic range pressure sensor based on two semicircle-holes microstructured fiber.

PubMed

Liu, Zhengyong; Htein, Lin; Lee, Kang-Kuen; Lau, Kin-Tak; Tam, Hwa-Yaw

2018-01-08

This paper presents a sensitive and large dynamic range pressure sensor based on a novel birefringence microstructured optical fiber (MOF) deployed in a Sagnac interferometer configuration. The MOF has two large semicircle holes in the cladding and a rectangular strut with germanium-doped core in the center. The fiber structure permits surrounding pressure to induce large effective index difference between the two polarized modes. The calculated and measured group birefringence of the fiber are 1.49 × 10 -4 , 1.23 × 10 -4 , respectively, at the wavelength of 1550 nm. Experimental results shown that the pressure sensitivity of the sensor varied from 45,000 pm/MPa to 50,000 pm/MPa, and minimum detectable pressure of 80 Pa and dynamic range of better than 116 dB could be achieved with the novel fiber sensor. The proposed sensor could be used in harsh environment and is an ideal candidate for downhole applications where high pressure measurement at elevated temperature up to 250 °C is needed.

Microgels for multiplex and direct fluorescence detection

NASA Astrophysics Data System (ADS)

Causa, Filippo; Aliberti, Anna; Cusano, Angela M.; Battista, Edmondo; Netti, Paolo A.

2015-05-01

Blood borne oligonucleotides fragments contain useful clinical information whose detection and monitoring represent the new frontier in liquid biopsy as they can transform the current diagnosis procedure. For instance, recent studies have identified a new class of circulating biomarkers such as s miRNAs, and demonstrated that changes in their concentration are closely associated with the development of cancer and other pathologies. However, direct detection of miRNAs in body fluids is particularly challenging and demands high sensitivity -concentration range between atto to femtomolarspecificity, and multiplexing Here we report on engineered multifunctional microgels and innovative probe design for a direct and multiplex detection of relevant clinical miRNAs in fluorescence by single particle assay. Polyethyleneglycol-based microgels have a coreshell architecture with two spectrally encoded fluorescent dyes for multiplex analyses and are endowed with fluorescent probes for miRNA detection. Encoding and detection fluorescence signals are distinguishable by not overlapping emission spectra. Tuneable fluorescence probe conjugation and corresponding emission confinement on single microgel allows for enhanced target detection. Such suspension array has indeed high selectivity and sensitivity with a detection limit of 10-15 M and a dynamic range from 10-9 to 10-15 M. We believe that sensitivity in the fM concentration range, signal background minimization, multiplexed capability and direct measurement of such microgels will translate into diagnostic benefits opening up new roots toward liquid biopsy in the context of point-of-care testing through an easy and fast detection of sensitive diagnostic biomarkers directly in serum.

The Rise of China in the International Trade Network: A Community Core Detection Approach

PubMed Central

Zhu, Zhen; Cerina, Federica; Chessa, Alessandro; Caldarelli, Guido; Riccaboni, Massimo

2014-01-01

Theory of complex networks proved successful in the description of a variety of complex systems ranging from biology to computer science and to economics and finance. Here we use network models to describe the evolution of a particular economic system, namely the International Trade Network (ITN). Previous studies often assume that globalization and regionalization in international trade are contradictory to each other. We re-examine the relationship between globalization and regionalization by viewing the international trade system as an interdependent complex network. We use the modularity optimization method to detect communities and community cores in the ITN during the years 1995–2011. We find rich dynamics over time both inter- and intra-communities. In particular, the Asia-Oceania community disappeared and reemerged over time along with a switch in leadership from Japan to China. We provide a multilevel description of the evolution of the network where the global dynamics (i.e., communities disappear or reemerge) and the regional dynamics (i.e., community core changes between community members) are related. Moreover, simulation results show that the global dynamics can be generated by a simple dynamic-edge-weight mechanism. PMID:25136895

The rise of China in the International Trade Network: a community core detection approach.

PubMed

Zhu, Zhen; Cerina, Federica; Chessa, Alessandro; Caldarelli, Guido; Riccaboni, Massimo

2014-01-01

Theory of complex networks proved successful in the description of a variety of complex systems ranging from biology to computer science and to economics and finance. Here we use network models to describe the evolution of a particular economic system, namely the International Trade Network (ITN). Previous studies often assume that globalization and regionalization in international trade are contradictory to each other. We re-examine the relationship between globalization and regionalization by viewing the international trade system as an interdependent complex network. We use the modularity optimization method to detect communities and community cores in the ITN during the years 1995-2011. We find rich dynamics over time both inter- and intra-communities. In particular, the Asia-Oceania community disappeared and reemerged over time along with a switch in leadership from Japan to China. We provide a multilevel description of the evolution of the network where the global dynamics (i.e., communities disappear or reemerge) and the regional dynamics (i.e., community core changes between community members) are related. Moreover, simulation results show that the global dynamics can be generated by a simple dynamic-edge-weight mechanism.

Vespertilionid bats control the width of their biosonar sound beam dynamically during prey pursuit

PubMed Central

Jakobsen, Lasse; Surlykke, Annemarie

2010-01-01

Animals using sound for communication emit directional signals, focusing most acoustic energy in one direction. Echolocating bats are listening for soft echoes from insects. Therefore, a directional biosonar sound beam greatly increases detection probability in the forward direction and decreases off-axis echoes. However, high directionality has context-specific disadvantages: at close range the detection space will be vastly reduced, making a broad beam favorable. Hence, a flexible system would be very advantageous. We investigated whether bats can dynamically change directionality of their biosonar during aerial pursuit of insects. We trained five Myotis daubentonii and one Eptesicus serotinus to capture tethered mealworms and recorded their echolocation signals with a multimicrophone array. The results show that the bats broaden the echolocation beam drastically in the terminal phase of prey pursuit. M. daubentonii increased the half-amplitude angle from approximately 40° to approximately 90° horizontally and from approximately 45° to more than 90° vertically. The increase in beam width is achieved by lowering the frequency by roughly one octave from approximately 55 kHz to approximately 27.5 kHz. The E. serotinus showed beam broadening remarkably similar to that of M. daubentonii. Our results demonstrate dynamic control of beam width in both species. Hence, we propose directionality as an explanation for the frequency decrease observed in the buzz of aerial hawking vespertilionid bats. We predict that future studies will reveal dynamic control of beam width in a broad range of acoustically communicating animals. PMID:20643943

Vespertilionid bats control the width of their biosonar sound beam dynamically during prey pursuit.

PubMed

Jakobsen, Lasse; Surlykke, Annemarie

2010-08-03

Animals using sound for communication emit directional signals, focusing most acoustic energy in one direction. Echolocating bats are listening for soft echoes from insects. Therefore, a directional biosonar sound beam greatly increases detection probability in the forward direction and decreases off-axis echoes. However, high directionality has context-specific disadvantages: at close range the detection space will be vastly reduced, making a broad beam favorable. Hence, a flexible system would be very advantageous. We investigated whether bats can dynamically change directionality of their biosonar during aerial pursuit of insects. We trained five Myotis daubentonii and one Eptesicus serotinus to capture tethered mealworms and recorded their echolocation signals with a multimicrophone array. The results show that the bats broaden the echolocation beam drastically in the terminal phase of prey pursuit. M. daubentonii increased the half-amplitude angle from approximately 40 degrees to approximately 90 degrees horizontally and from approximately 45 degrees to more than 90 degrees vertically. The increase in beam width is achieved by lowering the frequency by roughly one octave from approximately 55 kHz to approximately 27.5 kHz. The E. serotinus showed beam broadening remarkably similar to that of M. daubentonii. Our results demonstrate dynamic control of beam width in both species. Hence, we propose directionality as an explanation for the frequency decrease observed in the buzz of aerial hawking vespertilionid bats. We predict that future studies will reveal dynamic control of beam width in a broad range of acoustically communicating animals.

Know the Star, Know the Planet

DTIC Science & Technology

2011-11-01

Survey ( 2MASS ) and finally Section 5 summarizes our results. 2. DATA COLLECTION AND ANALYSIS Observations were made using the AEOS 3.6m telescope and...difficult to detect a companion with the expected dynamic range at that separation. 4. 2MASS ANALYSIS A check was made against the 2MASS Point Source...companion was found at 187.◦5 and 5.′′70, with ΔJ = 3.59. Mugrauer et al. (2005) detected this companion with AO in 2002 and noted the match with the 2MASS

ICESAT GLAS Altimetry Measurements: Received Signal Dynamic Range and Saturation Correction

NASA Technical Reports Server (NTRS)

Sun, Xiaoli; Abshire, James B.; Borsa, Adrian A.; Fricker, Helen Amanda; Yi, Donghui; Dimarzio, John P.; Paolo, Fernando S.; Brunt, Kelly M.; Harding, David J.; Neumann, Gregory A.

2017-01-01

NASAs Ice, Cloud, and land Elevation Satellite (ICESat), which operated between 2003 and 2009, made the first satellite-based global lidar measurement of earths ice sheet elevations, sea-ice thickness, and vegetation canopy structure. The primary instrument on ICESat was the Geoscience Laser Altimeter System (GLAS), which measured the distance from the spacecraft to the earth's surface via the roundtrip travel time of individual laser pulses. GLAS utilized pulsed lasers and a direct detection receiver consisting of a silicon avalanche photodiode and a waveform digitizer. Early in the mission, the peak power of the received signal from snow and ice surfaces was found to span a wider dynamic range than anticipated, often exceeding the linear dynamic range of the GLAS 1064-nm detector assembly. The resulting saturation of the receiver distorted the recorded signal and resulted in range biases as large as approximately 50 cm for ice- and snow-covered surfaces. We developed a correction for this saturation range bias based on laboratory tests using a spare flight detector, and refined the correction by comparing GLAS elevation estimates with those derived from Global Positioning System surveys over the calibration site at the salar de Uyuni, Bolivia. Applying the saturation correction largely eliminated the range bias due to receiver saturation for affected ICESat measurements over Uyuni and significantly reduced the discrepancies at orbit crossovers located on flat regions of the Antarctic ice sheet.

Experimental investigation on dynamic characteristics and strengthening mechanism of laser-induced cavitation bubbles.

PubMed

Ren, X D; He, H; Tong, Y Q; Ren, Y P; Yuan, S Q; Liu, R; Zuo, C Y; Wu, K; Sui, S; Wang, D S

2016-09-01

The dynamic features of nanosecond laser-induced cavitation bubbles near the light alloy boundary were investigated with the high-speed photography. The shock-waves and the dynamic characteristics of the cavitation bubbles generated by the laser were detected using the hydrophone. The dynamic features and strengthening mechanism of cavitation bubbles were studied. The strengthening mechanisms of cavitation bubble were discussed when the relative distance parameter γ was within the range of 0.5-2.5. It showed that the strengthening mechanisms caused by liquid jet or shock-waves depended on γ much. The research results provided a new strengthening method based on laser-induced cavitation shotless peening (CSP). Copyright © 2016 Elsevier B.V. All rights reserved.

Declining occurrence and low colonization probability in freshwater mussel assemblages: A dynamic occurrence modeling approach

USGS Publications Warehouse

Pandolfo, Tamara J.; Kwak, Thomas J.; Cope, W. Gregory; Heise, Ryan J.; Nichols, Robert B.; Pacifici, Krishna

2017-01-01

Mussel monitoring data are abundant, but methods for analyzing long-term trends in these data are often uninformative or have low power to detect changes. We used a dynamic occurrence model, which accounted for imperfect species detection in surveys, to assess changes in species occurrence in a longterm data set (1986–2011) for the Tar River basin of North Carolina, USA. Occurrence of all species decreased steadily over the time period studied. Occurrence in 1986 ranged from 0.19 for Utterbackia imbecillis to 0.60 for Fusconaia masoni. Occurrence in 2010–2011 ranged from 0.10 for Lampsilis radiata to 0.40 for F. masoni. The maximum difference between occurrence in 1986 and 2011 was a decline of 0.30 for Alasmidonta undulata. Mean persistence for all species was high (0.97, 95% CI ¼ 0.95–0.99); however, mean colonization probability was very low (,0.01, 95% CI ¼ ,0.01–0.01). These results indicate that mussels persisted at sites already occupied but that they have not colonized sites where they had not occurred previously. Our findings highlight the importance of modeling approaches that incorporate imperfect detection in estimating species occurrence and revealing temporal trends to inform conservation planning.

A new real-time method for investigation of affinity properties and binding kinetics of magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Orlov, Alexey V.; Nikitin, Maxim P.; Bragina, Vera A.; Znoyko, Sergey L.; Zaikina, Marina N.; Ksenevich, Tatiana I.; Gorshkov, Boris G.; Nikitin, Petr I.

2015-04-01

A method for quantitative investigation of affinity constants of receptors immobilized on magnetic nanoparticles (MP) is developed based on spectral correlation interferometry (SCI). The SCI records with a picometer resolution the thickness changes of a layer of molecules or nanoparticles due to a biochemical reaction on a cover slip, averaged over the sensing area. The method is compatible with other types of sensing surfaces employed in biosensing. The measured values of kinetic association constants of magnetic nanoparticles are 4 orders of magnitude higher than those of molecular antibody association with antigen. The developed method also suggests highly sensitive detection of antigens in a wide dynamic range. The limit of detection of 92 pg/ml has been demonstrated for prostate-specific antigen (PSA) with 50-nm MP employed as labels, which produce 3-order amplification of the SCI signals. The calibration curve features high sensitivity (slope) of 3-fold signal raise per 10-fold increase of PSA concentration within 4-order dynamic range, which is an attractive compromise for precise quantitative and highly sensitive immunoassay. The proposed biosensing technique offers inexpensive disposable sensor chips of cover slips and represents an economically sound alternative to traditional immunoassays for disease diagnostics, detection of pathogens in food and environmental monitoring.

Analysis on frequency response of trans-impedance amplifier (TIA) for signal-to-noise ratio (SNR) enhancement in optical signal detection system using lock-in amplifier (LIA)

NASA Astrophysics Data System (ADS)

Kim, Ji-Hoon; Jeon, Su-Jin; Ji, Myung-Gi; Park, Jun-Hee; Choi, Young-Wan

2017-02-01

Lock-in amplifier (LIA) has been widely used in optical signal detection systems because it can measure small signal under high noise level. Generally, The LIA used in optical signal detection system is composed of transimpedance amplifier (TIA), phase sensitive detector (PSD) and low pass filter (LPF). But commercial LIA using LPF is affected by flicker noise. To avoid flicker noise, there is 2ω detection LIA using BPF. To improve the dynamic reserve (DR) of the 2ω LIA, the signal to noise ratio (SNR) of the TIA should be improved. According to the analysis of frequency response of the TIA, the noise gain can be minimized by proper choices of input capacitor (Ci) and feed-back network in the TIA in a specific frequency range. In this work, we have studied how the SNR of the TIA can be improved by a proper choice of frequency range. We have analyzed the way to control this frequency range through the change of passive component in the TIA. The result shows that the variance of the passive component in the TIA can change the specific frequency range where the noise gain is minimized in the uniform gain region of the TIA.

Homeostatic enhancement of sensory transduction

PubMed Central

Milewski, Andrew R.; Ó Maoiléidigh, Dáibhid; Salvi, Joshua D.; Hudspeth, A. J.

2017-01-01

Our sense of hearing boasts exquisite sensitivity, precise frequency discrimination, and a broad dynamic range. Experiments and modeling imply, however, that the auditory system achieves this performance for only a narrow range of parameter values. Small changes in these values could compromise hair cells’ ability to detect stimuli. We propose that, rather than exerting tight control over parameters, the auditory system uses a homeostatic mechanism that increases the robustness of its operation to variation in parameter values. To slowly adjust the response to sinusoidal stimulation, the homeostatic mechanism feeds back a rectified version of the hair bundle’s displacement to its adaptation process. When homeostasis is enforced, the range of parameter values for which the sensitivity, tuning sharpness, and dynamic range exceed specified thresholds can increase by more than an order of magnitude. Signatures in the hair cell’s behavior provide a means to determine through experiment whether such a mechanism operates in the auditory system. Robustness of function through homeostasis may be ensured in any system through mechanisms similar to those that we describe here. PMID:28760949

76 FR 5330 - University of Chicago, et al.; Notice of Decision on Applications for Duty-Free Entry of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-31

.... Instrument: Pilatus 100K Pixel Detector System. Manufacturer: Dectris Ltd., Switzerland. Intended Use: See... detection scheme), high dynamic range (20- bits), and fast readout speeds. Docket Number: 10-068. Applicant... System. Manufacturer: Dectris Ltd., Switzerland. Intended Use: See Notice at 75 FR 82372, December 30...

Probing conformational dynamics by photoinduced electron transfer

NASA Astrophysics Data System (ADS)

Neuweiler, Hannes; Herten, Dirk P.; Marme, N.; Knemeyer, J. P.; Piestert, Oliver; Tinnefeld, Philip; Sauer, Marcus

2004-07-01

We demonstrate how photoinduced electron transfer (PET) reactions can be successfully applied to monitor conformational dynamics in individual biopolymers. Single-pair fluorescence resonance energy transfer (FRET) experiments are ideally suited to study conformational dynamics occurring on the nanometer scale, e.g. during protein folding or unfolding. In contrast, conformational dynamics with functional significance, for example occurring in enzymes at work, often appear on much smaller spatial scales of up to several Angströms. Our results demonstrate that selective PET-reactions between fluorophores and amino acids or DNA nucleotides represent a versatile tool to measure small-scale conformational dynamics in biopolymers on a wide range of time scales, extending from nanoseconds to seconds, at the single-molecule level under equilibrium conditions. That is, the monitoring of conformational dynamics of biopolymers with temporal resolutions comparable to those within reach using new techniques of molecular dynamic simulations. We present data about structural changes of single biomolecules like DNA hairpins and peptides by using quenching electron transfer reactions between guanosine or tryptophan residues in close proximity to fluorescent dyes. Furthermore, we demonstrate that the strong distance dependence of charge separation reactions on the sub-nanometer scale can be used to develop conformationally flexible PET-biosensors. These sensors enable the detection of specific target molecules in the sub-picomolar range and allow one to follow their molecular binding dynamics with temporal resolution.

Transistor analogs of emergent iono-neuronal dynamics.

PubMed

Rachmuth, Guy; Poon, Chi-Sang

2008-06-01

Neuromorphic analog metal-oxide-silicon (MOS) transistor circuits promise compact, low-power, and high-speed emulations of iono-neuronal dynamics orders-of-magnitude faster than digital simulation. However, their inherently limited input voltage dynamic range vs power consumption and silicon die area tradeoffs makes them highly sensitive to transistor mismatch due to fabrication inaccuracy, device noise, and other nonidealities. This limitation precludes robust analog very-large-scale-integration (aVLSI) circuits implementation of emergent iono-neuronal dynamics computations beyond simple spiking with limited ion channel dynamics. Here we present versatile neuromorphic analog building-block circuits that afford near-maximum voltage dynamic range operating within the low-power MOS transistor weak-inversion regime which is ideal for aVLSI implementation or implantable biomimetic device applications. The fabricated microchip allowed robust realization of dynamic iono-neuronal computations such as coincidence detection of presynaptic spikes or pre- and postsynaptic activities. As a critical performance benchmark, the high-speed and highly interactive iono-neuronal simulation capability on-chip enabled our prompt discovery of a minimal model of chaotic pacemaker bursting, an emergent iono-neuronal behavior of fundamental biological significance which has hitherto defied experimental testing or computational exploration via conventional digital or analog simulations. These compact and power-efficient transistor analogs of emergent iono-neuronal dynamics open new avenues for next-generation neuromorphic, neuroprosthetic, and brain-machine interface applications.

A new microfluidic approach for the one-step capture, amplification and label-free quantification of bacteria from raw samples.

PubMed

Pereiro, Iago; Bendali, Amel; Tabnaoui, Sanae; Alexandre, Lucile; Srbova, Jana; Bilkova, Zuzana; Deegan, Shane; Joshi, Lokesh; Viovy, Jean-Louis; Malaquin, Laurent; Dupuy, Bruno; Descroix, Stéphanie

2017-02-01

A microfluidic method to specifically capture and detect infectious bacteria based on immunorecognition and proliferative power is presented. It involves a microscale fluidized bed in which magnetic and drag forces are balanced to retain antibody-functionalized superparamagnetic beads in a chamber during sample perfusion. Captured cells are then cultivated in situ by infusing nutritionally-rich medium. The system was validated by the direct one-step detection of Salmonella Typhimurium in undiluted unskimmed milk, without pre-treatment. The growth of bacteria induces an expansion of the fluidized bed, mainly due to the volume occupied by the newly formed bacteria. This expansion can be observed with the naked eye, providing simple low-cost detection of only a few bacteria and in a few hours. The time to expansion can also be measured with a low-cost camera, allowing quantitative detection down to 4 cfu (colony forming unit), with a dynamic range of 100 to 10 7 cfu ml -1 in 2 to 8 hours, depending on the initial concentration. This mode of operation is an equivalent of quantitative PCR, with which it shares a high dynamic range and outstanding sensitivity and specificity, operating at the live cell rather than DNA level. Specificity was demonstrated by controls performed in the presence of a 500× excess of non-pathogenic Lactococcus lactis . The system's versatility was demonstrated by its successful application to the detection and quantitation of Escherichia coli O157:H15 and Enterobacter cloacae . This new technology allows fast, low-cost, portable and automated bacteria detection for various applications in food, environment, security and clinics.

Nanoparticle Enhancement Cascade for Sensitive Multiplex Measurements of Biomarkers in Complex Fluids with Surface Plasmon Resonance Imaging.

PubMed

Hendriks, Jan; Stojanovic, Ivan; Schasfoort, Richard B M; Saris, Daniël B F; Karperien, Marcel

2018-06-05

There is a large unmet need for reliable biomarker measurement systems for clinical application. Such systems should meet challenging requirements for large scale use, including a large dynamic detection range, multiplexing capacity, and both high specificity and sensitivity. More importantly, these requirements need to apply to complex biological samples, which require extensive quality control. In this paper, we present the development of an enhancement detection cascade for surface plasmon resonance imaging (SPRi). The cascade applies an antibody sandwich assay, followed by neutravidin and a gold nanoparticle enhancement for quantitative biomarker measurements in small volumes of complex fluids. We present a feasibility study both in simple buffers and in spiked equine synovial fluid with four cytokines, IL-1β, IL-6, IFN-γ, and TNF-α. Our enhancement cascade leads to an antibody dependent improvement in sensitivity up to 40 000 times, resulting in a limit of detection as low as 50 fg/mL and a dynamic detection range of more than 7 logs. Additionally, measurements at these low concentrations are highly reliable with intra- and interassay CVs between 2% and 20%. We subsequently showed this assay is suitable for multiplex measurements with good specificity and limited cross-reactivity. Moreover, we demonstrated robust detection of IL-6 and IL-1β in spiked undiluted equine synovial fluid with small variation compared to buffer controls. In addition, the availability of real time measurements provides extensive quality control opportunities, essential for clinical applications. Therefore, we consider this method is suitable for broad application in SPRi for multiplex biomarker detection in both research and clinical settings.

Mutual promotion of electrochemical-localized surface plasmon resonance on nanochip for sensitive sialic acid detection.

PubMed

Li, Shuang; Liu, Jinglong; Lu, Yanli; Zhu, Long; Li, Candong; Hu, Lijiang; Li, Jun; Jiang, Jing; Low, Szeshin; Liu, Qingjun

2018-06-01

Localized surface plasmon resonance (LSPR) induced charge separation were concentrated on the metal nanoparticles surface, which made it sensitive to the surface refractive index changes during optical sensing. Similarly, electrochemical detection was based on the electron transformation on the electrode surface. Herein, we fabricated a nanochip by decorating a nanocone-array substrate with gold nanoparticles and silver nanoparticles for dynamic electro-optical spectroscopy. Mercaptophenyl boronic acid (MPBA) was immobilized firmly on the nanochip by the metal-S bond for sensitive sialic acid sensing. Owing to the high stability of gold nanoparticles and the high sensitivity of silver nanoparticles, the nanochip showed good performance in LSPR detection with rich and high responses. Besides, the nanochip also showed sensitive electrical signals during electrochemical detection due to the excitation of the energetic charges from the nanoparticles surface to the reaction system. The dynamic electro-optical spectroscopy was based on a unique combination of LSPR and linear sweep voltammetry (LSV). On the one hand, electrochemical signals activated the electrons on the nanochip to promote the propagation and resonance of surface plasmon. On the other hand, LSPR concentrated the electrons on the nanochip surface, which made the electrons easily driven to enhance the current in electrochemical detection. Results showed that mutual promotion of electrochemical-LSPR on nanochip covered a linear dynamic range from 0.05 mM to 5 mM on selective sialic acid detection with a low detection limit of 17 μM. The synchronous amplification of the electro-optical response during electrochemical-LSPR, opened up a new perspective for efficient and sensitive biochemical detection. Copyright © 2018 Elsevier B.V. All rights reserved.

Possible Detection of GEMINID 2007 Meteor Shower During Day-Time from VLF Radiation Spectra

NASA Astrophysics Data System (ADS)

Guha, Anirban; de, Barin Kumar; Roy, Rakesh

2009-06-01

The results of day-time detection of GEMINID 2007 meteor shower from dynamic VLF radiation spectra in Tripura (23.50° N, 91.25° E), India, is presented here. The field experiments were performed during 12-17th December, 2007 inside Tripura University campus located at a hilly place in the North-Eastern part of India. A well calibrated software VLF receiver was used to perform the field experiments. Analyses of data reveal an hourly average rate of the shower around 50. The VLF emissions lie in the range from 8 kHz to 13 kHz which is 10 to 15 times higher than previous reports. The mean duration of each VLF emission calculated from dynamic spectra is found to be 6 s and the mean bandwidth is 3.6 kHz. The temporal variation of VLF emission duration and bandwidth of VLF radiation is also studied. The results strongly support the fact that VLF electromagnetic waves are produced during the passage of meteors in the atmosphere. The experiment also makes the study of dynamic VLF spectra as a strong tool to detect low intensity meteor shower during daytime.

Fiber-Optic/Photoelastic Flow Sensors

NASA Technical Reports Server (NTRS)

Wesson, Laurence N.; Cabato, Nellie L.; Brooks, Edward F.

1995-01-01

Simple, rugged, lightweight transducers detect periodic vortices. Fiber-optic-coupled transducers developed to measure flows over wide dynamic ranges and over wide temperature ranges in severe environments. Used to measure flows of fuel in advanced aircraft engines. Feasibility of sensors demonstrated in tests of prototype sensor in water flowing at various temperatures and speeds. Particularly attractive for aircraft applications because optical fibers compact and make possible transmission of sensor signals at high rates with immunity from electromagnetic interference at suboptical frequencies. Sensors utilize optical-to-optical conversion via photoelastic effect.

Dynamic nuclear magnetic resonance field sensing with part-per-trillion resolution

PubMed Central

Gross, Simon; Barmet, Christoph; Dietrich, Benjamin E.; Brunner, David O.; Schmid, Thomas; Pruessmann, Klaas P.

2016-01-01

High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude. The relative sensitivity thus achieved amounts to 1 part per trillion (10−12). To exemplify this capability we demonstrate the direct detection and relaxometry of nuclear polarization and real-time recording of dynamic susceptibility effects related to human heart function. Enhanced high-field magnetometry will generally permit a fresh look at magnetic phenomena that scale with field strength. It also promises to facilitate the development and operation of high-field magnets. PMID:27910860

An integrated platform for biomolecule interaction analysis

NASA Astrophysics Data System (ADS)

Jan, Chia-Ming; Tsai, Pei-I.; Chou, Shin-Ting; Lee, Shu-Sheng; Lee, Chih-Kung

2013-02-01

We developed a new metrology platform which can detect real-time changes in both a phase-interrogation mode and intensity mode of a SPR (surface plasmon resonance). We integrated a SPR and ellipsometer to a biosensor chip platform to create a new biomolecular interaction measurement mechanism. We adopted a conductive ITO (indium-tinoxide) film to the bio-sensor platform chip to expand the dynamic range and improve measurement accuracy. The thickness of the conductive film and the suitable voltage constants were found to enhance performance. A circularly polarized ellipsometry configuration was incorporated into the newly developed platform to measure the label-free interactions of recombinant human C-reactive protein (CRP) with immobilized biomolecule target monoclonal human CRP antibody at various concentrations. CRP was chosen as it is a cardiovascular risk biomarker and is an acute phase reactant as well as a specific prognostic indicator for inflammation. We found that the sensitivity of a phaseinterrogation SPR is predominantly dependent on the optimization of the sample incidence angle. The effect of the ITO layer effective index under DC and AC effects as well as an optimal modulation were experimentally performed and discussed. Our experimental results showed that the modulated dynamic range for phase detection was 10E-2 RIU based on a current effect and 10E-4 RIU based on a potential effect of which a 0.55 (°/RIU) measurement was found by angular-interrogation. The performance of our newly developed metrology platform was characterized to have a higher sensitivity and less dynamic range when compared to a traditional full-field measurement system.

Laser development for optimal helicopter obstacle warning system LADAR performance

NASA Astrophysics Data System (ADS)

Yaniv, A.; Krupkin, V.; Abitbol, A.; Stern, J.; Lurie, E.; German, A.; Solomonovich, S.; Lubashitz, B.; Harel, Y.; Engart, S.; Shimoni, Y.; Hezy, S.; Biltz, S.; Kaminetsky, E.; Goldberg, A.; Chocron, J.; Zuntz, N.; Zajdman, A.

2005-04-01

Low lying obstacles present immediate danger to both military and civilian helicopters performing low-altitude flight missions. A LADAR obstacle detection system is the natural solution for enhancing helicopter safety and improving the pilot situation awareness. Elop is currently developing an advanced Surveillance and Warning Obstacle Ranging and Display (SWORD) system for the Israeli Air Force. Several key factors and new concepts have contributed to system optimization. These include an adaptive FOV, data memorization, autonomous obstacle detection and warning algorithms and the use of an agile laser transmitter. In the present work we describe the laser design and performance and discuss some of the experimental results. Our eye-safe laser is characterized by its pulse energy, repetition rate and pulse length agility. By dynamically controlling these parameters, we are able to locally optimize the system"s obstacle detection range and scan density in accordance with the helicopter instantaneous maneuver.

Relaxometry imaging of superparamagnetic magnetite nanoparticles at ambient conditions

NASA Astrophysics Data System (ADS)

Finkler, Amit; Schmid-Lorch, Dominik; Häberle, Thomas; Reinhard, Friedemann; Zappe, Andrea; Slota, Michael; Bogani, Lapo; Wrachtrup, Jörg

We present a novel technique to image superparamagnetic iron oxide nanoparticles via their fluctuating magnetic fields. The detection is based on the nitrogen-vacancy (NV) color center in diamond, which allows optically detected magnetic resonance (ODMR) measurements on its electron spin structure. In combination with an atomic-force-microscope, this atomic-sized color center maps ambient magnetic fields in a wide frequency range from DC up to several GHz, while retaining a high spatial resolution in the sub-nanometer range. We demonstrate imaging of single 10 nm sized magnetite nanoparticles using this spin noise detection technique. By fitting simulations (Ornstein-Uhlenbeck process) to the data, we are able to infer additional information on such a particle and its dynamics, like the attempt frequency and the anisotropy constant. This is of high interest to the proposed application of magnetite nanoparticles as an alternative MRI contrast agent or to the field of particle-aided tumor hyperthermia.

3D change detection - Approaches and applications

NASA Astrophysics Data System (ADS)

Qin, Rongjun; Tian, Jiaojiao; Reinartz, Peter

2016-12-01

Due to the unprecedented technology development of sensors, platforms and algorithms for 3D data acquisition and generation, 3D spaceborne, airborne and close-range data, in the form of image based, Light Detection and Ranging (LiDAR) based point clouds, Digital Elevation Models (DEM) and 3D city models, become more accessible than ever before. Change detection (CD) or time-series data analysis in 3D has gained great attention due to its capability of providing volumetric dynamics to facilitate more applications and provide more accurate results. The state-of-the-art CD reviews aim to provide a comprehensive synthesis and to simplify the taxonomy of the traditional remote sensing CD techniques, which mainly sit within the boundary of 2D image/spectrum analysis, largely ignoring the particularities of 3D aspects of the data. The inclusion of 3D data for change detection (termed 3D CD), not only provides a source with different modality for analysis, but also transcends the border of traditional top-view 2D pixel/object-based analysis to highly detailed, oblique view or voxel-based geometric analysis. This paper reviews the recent developments and applications of 3D CD using remote sensing and close-range data, in support of both academia and industry researchers who seek for solutions in detecting and analyzing 3D dynamics of various objects of interest. We first describe the general considerations of 3D CD problems in different processing stages and identify CD types based on the information used, being the geometric comparison and geometric-spectral analysis. We then summarize relevant works and practices in urban, environment, ecology and civil applications, etc. Given the broad spectrum of applications and different types of 3D data, we discuss important issues in 3D CD methods. Finally, we present concluding remarks in algorithmic aspects of 3D CD.

Optically modulated fluorescence bioimaging: visualizing obscured fluorophores in high background.

PubMed

Hsiang, Jung-Cheng; Jablonski, Amy E; Dickson, Robert M

2014-05-20

Fluorescence microscopy and detection have become indispensible for understanding organization and dynamics in biological systems. Novel fluorophores with improved brightness, photostability, and biocompatibility continue to fuel further advances but often rely on having minimal background. The visualization of interactions in very high biological background, especially for proteins or bound complexes at very low copy numbers, remains a primary challenge. Instead of focusing on molecular brightness of fluorophores, we have adapted the principles of high-sensitivity absorption spectroscopy to improve the sensitivity and signal discrimination in fluorescence bioimaging. Utilizing very long wavelength transient absorptions of kinetically trapped dark states, we employ molecular modulation schemes that do not simultaneously modulate the background fluorescence. This improves the sensitivity and ease of implementation over high-energy photoswitch-based recovery schemes, as no internal dye reference or nanoparticle-based fluorophores are needed to separate the desired signals from background. In this Account, we describe the selection process for and identification of fluorophores that enable optically modulated fluorescence to decrease obscuring background. Differing from thermally stable photoswitches using higher-energy secondary lasers, coillumination at very low energies depopulates transient dark states, dynamically altering the fluorescence and giving characteristic modulation time scales for each modulatable emitter. This process is termed synchronously amplified fluorescence image recovery (SAFIRe) microscopy. By understanding and optically controlling the dye photophysics, we selectively modulate desired fluorophore signals independent of all autofluorescent background. This shifts the fluorescence of interest to unique detection frequencies with nearly shot-noise-limited detection, as no background signals are collected. Although the fluorescence brightness is improved slightly, SAFIRe yields up to 100-fold improved signal visibility by essentially removing obscuring, unmodulated background (Richards, C. I.; J. Am. Chem. Soc. 2009, 131, 4619). While SAFIRe exhibits a wide, linear dynamic range, we have demonstrated single-molecule signal recovery buried within 200 nM obscuring dye. In addition to enabling signal recovery through background reduction, each dye exhibits a characteristic modulation frequency indicative of its photophysical dynamics. Thus, these characteristic time scales offer opportunities not only to expand the dimensionality of fluorescence imaging by using dark-state lifetimes but also to distinguish the dynamics of subpopulations on the basis of photophysical versus diffusional time scales, even within modulatable populations. The continued development of modulation for signal recovery and observation of biological dynamics holds great promise for studying a range of transient biological phenomena in natural environments. Through the development of a wide range of fluorescent proteins, organic dyes, and inorganic emitters that exhibit significant dark-state populations under steady-state illumination, we can drastically expand the applicability of fluorescence imaging to probe lower-abundance complexes and their dynamics.

Smart textile plasmonic fiber dew sensors.

PubMed

Esmaeilzadeh, Hamid; Rivard, Maxime; Arzi, Ezatollah; Légaré, François; Hassani, Alireza

2015-06-01

We propose a novel Surface Plasmon Resonance (SPR)-based sensor that detects dew formation in optical fiber-based smart textiles. The proposed SPR sensor facilitates the observation of two phenomena: condensation of moisture and evaporation of water molecules in air. This sensor detects dew formation in less than 0.25 s, and determines dew point temperature with an accuracy of 4%. It can be used to monitor water layer depth changes during dew formation and evaporation in the range of a plasmon depth probe, i.e., 250 nm, with a resolution of 7 nm. Further, it facilitates estimation of the relative humidity of a medium over a dynamic range of 30% to 70% by measuring the evaporation time via the plasmon depth probe.

Lysozyme as a recognition element for monitoring of bacterial population.

PubMed

Zheng, Laibao; Wan, Yi; Yu, Liangmin; Zhang, Dun

2016-01-01

Bacterial infections remain a significant challenge in biomedicine and environment safety. Increasing worldwide demand for point-of-care techniques and increasing concern on their safe development and use, require a simple and sensitive bioanalysis for pathogen detection. However, this goal is not yet achieved. A design for fluorescein isothiocyanate-labeled lysozyme (FITC-LYZ), which provides quantitative binding information for gram-positive bacteria, Micrococcus luteus, and detects pathogen concentration, is presented. The functional lysozyme is used not only as the pathogenic detection platform, but also as a tracking reagent for microbial population in antibacterial tests. A nonlinear relationship between the system response and the logarithm of the bacterial concentration was observed in the range of 1.2×10(2)-1.2×10(5) cfu mL(-1). The system has a potential for further applications and provides a facile and simple method for detection of pathogenic bacteria. Meanwhile, the fluorescein isothiocyanate -labeled lysozyme is also employed as the tracking agent for antibacterial dynamic assay, which show a similar dynamic curve compared with UV-vis test. Copyright © 2015 Elsevier B.V. All rights reserved.

Using natural archives to detect climate and environmental tipping points in the Earth System

NASA Astrophysics Data System (ADS)

Thomas, Zoë A.

2016-11-01

'Tipping points' in the Earth system are characterised by a nonlinear response to gradual forcing, and may have severe and wide-ranging impacts. Many abrupt events result from simple underlying system dynamics termed 'critical transitions' or 'bifurcations'. One of the best ways to identify and potentially predict threshold behaviour in the climate system is through analysis of natural ('palaeo') archives. Specifically, on the approach to a tipping point, early warning signals can be detected as characteristic fluctuations in a time series as a system loses stability. Testing whether these early warning signals can be detected in highly complex real systems is a key challenge, since much work is either theoretical or only tested with simple models. This is particularly problematic in palaeoclimate and palaeoenvironmental records with low resolution, non-equidistant data, which can limit accurate analysis. Here, a range of different datasets are examined to explore generic rules that can be used to detect such dramatic events. A number of key criteria are identified to be necessary for the reliable identification of early warning signals in natural archives, most crucially, the need for a low-noise record of sufficient data length, resolution and accuracy. A deeper understanding of the underlying system dynamics is required to inform the development of more robust system-specific indicators, or to indicate the temporal resolution required, given a known forcing. This review demonstrates that time series precursors from natural archives provide a powerful means of forewarning tipping points within the Earth System.

A Sensitive DNA Capacitive Biosensor Using Interdigitated Electrodes

PubMed Central

Wang, Lei; Veselinovic, Milena; Yang, Lang; Geiss, Brian J.; Dandy, David S.; Chen, Tom

2017-01-01

This paper presents a label-free affinity-based capacitive biosensor using interdigitated electrodes. Using an optimized process of DNA probe preparation to minimize the effect of contaminants in commercial thiolated DNA probe, the electrode surface was functionalized with the 24-nucleotide DNA probes based on the West Nile virus sequence (Kunjin strain). The biosensor has the ability to detect complementary DNA fragments with a detection limit down to 20 DNA target molecules (1.5 aM range), making it suitable for a practical point-of-care (POC) platform for low target count clinical applications without the need for amplification. The reproducibility of the biosensor detection was improved with efficient covalent immobilization of purified single-stranded DNA probe oligomers on cleaned gold microelectrodes. In addition to the low detection limit, the biosensor showed a dynamic range of detection from 1 μL−1 to 105 μL−1 target molecules (20 to 2 million targets), making it suitable for sample analysis in a typical clinical application environment. The binding results presented in this paper were validated using fluorescent oligomers. PMID:27619528

Simple detection of residual enrofloxacin in meat products using microparticles and biochips.

PubMed

Ha, Mi-Sun; Chung, Myung-Sub; Bae, Dong-Ho

2016-05-01

A simple and sensitive method for detecting enrofloxacin, a major veterinary fluoroquinolone, was developed. Monoclonal antibody specific for enrofloxacin was immobilised on a chip and fluorescent dye-labelled microparticles were covalently bound to the enrofloxacin molecules. Enrofloxacin in solution competes with the microparticle-immobilised enrofloxacin (enroMPs) to bind to the antibody on the chip. The presence of enrofloxacin was verified by detecting the fluorescence of enrofloxacin-bound microparticles. Under optimum conditions, a high dynamic range was achieved at enrofloxacin concentrations ranging from 1 to 1000 μg kg(-1). The limits of detection and quantification for standard solutions were 5 and 20 μg kg(-1) respectively, which are markedly lower than the maximum residue limit. Using simple extraction methods, recoveries from fortified beef, pork and chicken samples were 43.4-62.3%. This novel method also enabled approximate quantification of enrofloxacin concentration: the enroMP signal intensity decreased with increasing enrofloxacin concentration. Because of its sensitivity, specificity, simplicity and rapidity, the method described herein will facilitate the detection and approximate quantification of enrofloxacin residues in foods in a high-throughput manner.

A Dynamic Intrusion Detection System Based on Multivariate Hotelling's T2 Statistics Approach for Network Environments

PubMed Central

Avalappampatty Sivasamy, Aneetha; Sundan, Bose

2015-01-01

The ever expanding communication requirements in today's world demand extensive and efficient network systems with equally efficient and reliable security features integrated for safe, confident, and secured communication and data transfer. Providing effective security protocols for any network environment, therefore, assumes paramount importance. Attempts are made continuously for designing more efficient and dynamic network intrusion detection models. In this work, an approach based on Hotelling's T2 method, a multivariate statistical analysis technique, has been employed for intrusion detection, especially in network environments. Components such as preprocessing, multivariate statistical analysis, and attack detection have been incorporated in developing the multivariate Hotelling's T2 statistical model and necessary profiles have been generated based on the T-square distance metrics. With a threshold range obtained using the central limit theorem, observed traffic profiles have been classified either as normal or attack types. Performance of the model, as evaluated through validation and testing using KDD Cup'99 dataset, has shown very high detection rates for all classes with low false alarm rates. Accuracy of the model presented in this work, in comparison with the existing models, has been found to be much better. PMID:26357668

A Dynamic Intrusion Detection System Based on Multivariate Hotelling's T2 Statistics Approach for Network Environments.

PubMed

Sivasamy, Aneetha Avalappampatty; Sundan, Bose

2015-01-01

The ever expanding communication requirements in today's world demand extensive and efficient network systems with equally efficient and reliable security features integrated for safe, confident, and secured communication and data transfer. Providing effective security protocols for any network environment, therefore, assumes paramount importance. Attempts are made continuously for designing more efficient and dynamic network intrusion detection models. In this work, an approach based on Hotelling's T(2) method, a multivariate statistical analysis technique, has been employed for intrusion detection, especially in network environments. Components such as preprocessing, multivariate statistical analysis, and attack detection have been incorporated in developing the multivariate Hotelling's T(2) statistical model and necessary profiles have been generated based on the T-square distance metrics. With a threshold range obtained using the central limit theorem, observed traffic profiles have been classified either as normal or attack types. Performance of the model, as evaluated through validation and testing using KDD Cup'99 dataset, has shown very high detection rates for all classes with low false alarm rates. Accuracy of the model presented in this work, in comparison with the existing models, has been found to be much better.

Scintillator high-gain avalanche rushing photoconductor active-matrix flat panel imager: Zero-spatial frequency x-ray imaging properties of the solid-state SHARP sensor structure

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

Wronski, M.; Zhao, W.; Tanioka, K.

Purpose: The authors are investigating the feasibility of a new type of solid-state x-ray imaging sensor with programmable avalanche gain: scintillator high-gain avalanche rushing photoconductor active matrix flat panel imager (SHARP-AMFPI). The purpose of the present work is to investigate the inherent x-ray detection properties of SHARP and demonstrate its wide dynamic range through programmable gain. Methods: A distributed resistive layer (DRL) was developed to maintain stable avalanche gain operation in a solid-state HARP. The signal and noise properties of the HARP-DRL for optical photon detection were investigated as a function of avalanche gain both theoretically and experimentally, and themore » results were compared with HARP tube (with electron beam readout) used in previous investigations of zero spatial frequency performance of SHARP. For this new investigation, a solid-state SHARP x-ray image sensor was formed by direct optical coupling of the HARP-DRL with a structured cesium iodide (CsI) scintillator. The x-ray sensitivity of this sensor was measured as a function of avalanche gain and the results were compared with the sensitivity of HARP-DRL measured optically. The dynamic range of HARP-DRL with variable avalanche gain was investigated for the entire exposure range encountered in radiography/fluoroscopy (R/F) applications. Results: The signal from HARP-DRL as a function of electric field showed stable avalanche gain, and the noise associated with the avalanche process agrees well with theory and previous measurements from a HARP tube. This result indicates that when coupled with CsI for x-ray detection, the additional noise associated with avalanche gain in HARP-DRL is negligible. The x-ray sensitivity measurements using the SHARP sensor produced identical avalanche gain dependence on electric field as the optical measurements with HARP-DRL. Adjusting the avalanche multiplication gain in HARP-DRL enabled a very wide dynamic range which encompassed all clinically relevant medical x-ray exposures. Conclusions: This work demonstrates that the HARP-DRL sensor enables the practical implementation of a SHARP solid-state x-ray sensor capable of quantum noise limited operation throughout the entire range of clinically relevant x-ray exposures. This is an important step toward the realization of a SHARP-AMFPI x-ray flat-panel imager.« less

Nonenzymatic all-solid-state coated wire electrode for acetylcholine determination in vitro.

PubMed

He, Cheng; Wang, Zhan; Wang, You; Hu, Ruifen; Li, Guang

2016-11-15

A nonenzymatic all-solid-state coated wire acetylcholine electrode was investigated. Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT/PSS) as conducting polymer was coated on one end of a gold wire (0.5mm in diameter). The acetylcholine selective membrane containing heptakis(2,3,6-tri-Ο-methyl)-β-cyclodextrin as an ionophore covered the conducting polymer layer. The electrode could work stably in a pH range of 6.5-8.5 and a temperature range of 15-40°C. It covered an acetylcholine concentration range of 10(-5)-10(-1)M with a slope of 54.04±1.70mV/decade, while detection limit was 5.69±1.06µM. The selectivity, dynamic response, reproducibility and stability were evaluated. The electrode could work properly in the rat brain homogenate to detect different concentrations of acetylcholine. Copyright © 2016 Elsevier B.V. All rights reserved.

Specific 13C labeling of leucine, valine and isoleucine methyl groups for unambiguous detection of long-range restraints in protein solid-state NMR studies

NASA Astrophysics Data System (ADS)

Fasshuber, Hannes Klaus; Demers, Jean-Philippe; Chevelkov, Veniamin; Giller, Karin; Becker, Stefan; Lange, Adam

2015-03-01

Here we present an isotopic labeling strategy to easily obtain unambiguous long-range distance restraints in protein solid-state NMR studies. The method is based on the inclusion of two biosynthetic precursors in the bacterial growth medium, α-ketoisovalerate and α-ketobutyrate, leading to the production of leucine, valine and isoleucine residues that are exclusively 13C labeled on methyl groups. The resulting spectral simplification facilitates the collection of distance restraints, the verification of carbon chemical shift assignments and the measurement of methyl group dynamics. This approach is demonstrated on the type-three secretion system needle of Shigella flexneri, where 49 methyl-methyl and methyl-nitrogen distance restraints including 10 unambiguous long-range distance restraints could be collected. By combining this labeling scheme with ultra-fast MAS and proton detection, the assignment of methyl proton chemical shifts was achieved.

Haul truck tire dynamics due to tire condition

NASA Astrophysics Data System (ADS)

Vaghar Anzabi, R.; Nobes, D. S.; Lipsett, M. G.

2012-05-01

Pneumatic tires are costly components on large off-road haul trucks used in surface mining operations. Tires are prone to damage during operation, and these events can lead to injuries to personnel, loss of equipment, and reduced productivity. Damage rates have significant variability, due to operating conditions and a range of tire fault modes. Currently, monitoring of tire condition is done by physical inspection; and the mean time between inspections is often longer than the mean time between incipient failure and functional failure of the tire. Options for new condition monitoring methods include off-board thermal imaging and camera-based optical methods for detecting abnormal deformation and surface features, as well as on-board sensors to detect tire faults during vehicle operation. Physics-based modeling of tire dynamics can provide a good understanding of the tire behavior, and give insight into observability requirements for improved monitoring systems. This paper describes a model to simulate the dynamics of haul truck tires when a fault is present to determine the effects of physical parameter changes that relate to faults. To simulate the dynamics, a lumped mass 'quarter-vehicle' model has been used to determine the response of the system to a road profile when a failure changes the original properties of the tire. The result is a model of tire vertical displacement that can be used to detect a fault, which will be tested under field conditions in time-varying conditions.

Non-local detection of spin dynamics via spin rectification effect in yttrium iron garnet/SiO{sub 2}/NiFe trilayers near simultaneous ferromagnetic resonance

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

Soh, Wee Tee, E-mail: a0046479@u.nus.edu; Ong, C. K.; Peng, Bin

2015-08-15

The spin rectification effect (SRE), a phenomenon that generates dc voltages from ac microwave fields incident onto a conducting ferromagnet, has attracted widespread attention due to its high sensitivity to ferromagnetic resonance (FMR) as well as its relevance to spintronics. Here, we report the non-local detection of yttrium iron garnet (YIG) spin dynamics by measuring SRE voltages from an adjacent conducting NiFe layer up to 200 nm thick. In particular, we detect, within the NiFe layer, SRE voltages stemming from magnetostatic surface spin waves (MSSWs) of the adjacent bulk YIG which are excited by a shorted coaxial probe. These non-localmore » SRE voltages within the NiFe layer that originates from YIG MSSWs are present even in 200 nm-thick NiFe films with a 50 nm thick SiO{sub 2} spacer between NiFe and YIG, thus strongly ruling out the mechanism of spin-pumping induced inverse spin Hall effect in NiFe as the source of these voltages. This long-range influence of YIG dynamics is suggested to be mediated by dynamic fields generated from YIG spin precession near YIG/NiFe interface, which interacts with NiFe spins near the simultaneous resonance of both spins, to generate a non-local SRE voltage within the NiFe layer.« less

Specific and quantitative detection of human polyomaviruses BKV, JCV, and SV40 by real time PCR.

PubMed

McNees, Adrienne L; White, Zoe S; Zanwar, Preeti; Vilchez, Regis A; Butel, Janet S

2005-09-01

The polyomaviruses that infect humans, BK virus (BKV), JC virus (JCV), and simian virus 40 (SV40), typically establish subclinical persistent infections. However, reactivation of these viruses in immunocompromised hosts is associated with renal nephropathy and hemorrhagic cystitis (HC) caused by BKV and with progressive multifocal leukoencephalopathy (PML) caused by JCV. Additionally, SV40 is associated with several types of human cancers including primary brain and bone cancers, mesotheliomas, and non-Hodgkin's lymphoma. Advancements in detection of these viruses may contribute to improved diagnosis and treatment of affected patients. To develop sensitive and specific real time quantitative polymerase chain reaction (RQ-PCR) assays for the detection of T-antigen DNA sequences of the human polyomaviruses BKV, JCV, and SV40 using the ABI Prism 7000 Sequence Detection System. Assays for absolute quantification of the viral T-ag sequences were designed and the sensitivity and specificity were evaluated. A quantitative assay to measure the single copy human RNAse P gene was also developed and evaluated in order to normalize viral gene copy numbers to cell numbers. Quantification of the target genes is sensitive and specific over a 7 log dynamic range. Ten copies each of the viral and cellular genes are reproducibly and accurately detected. The sensitivity of detection of the RQ-PCR assays is increased 10- to 100-fold compared to conventional PCR and agarose gel protocols. The primers and probes used to detect the viral genes are specific for each virus and there is no cross reactivity within the dynamic range of the standard dilutions. The sensitivity of detection for these assays is not reduced in human cellular extracts; however, different DNA extraction protocols may affect quantification. These assays provide a technique for rapid and specific quantification of polyomavirus genomes per cell in human samples.

Real-time maritime scene simulation for ladar sensors

NASA Astrophysics Data System (ADS)

Christie, Chad L.; Gouthas, Efthimios; Swierkowski, Leszek; Williams, Owen M.

2011-06-01

Continuing interest exists in the development of cost-effective synthetic environments for testing Laser Detection and Ranging (ladar) sensors. In this paper we describe a PC-based system for real-time ladar scene simulation of ships and small boats in a dynamic maritime environment. In particular, we describe the techniques employed to generate range imagery accompanied by passive radiance imagery. Our ladar scene generation system is an evolutionary extension of the VIRSuite infrared scene simulation program and includes all previous features such as ocean wave simulation, the physically-realistic representation of boat and ship dynamics, wake generation and simulation of whitecaps, spray, wake trails and foam. A terrain simulation extension is also under development. In this paper we outline the development, capabilities and limitations of the VIRSuite extensions.

LLR data analysis and impact on lunar dynamics from recent developments at OCA LLR Station

NASA Astrophysics Data System (ADS)

Viswanathan, Vishnu; Fienga, Agnes; Courde, Clement; Torre, Jean-Marie; Exertier, Pierre; Samain, Etienne; Feraudy, Dominique; Albanese, Dominique; Aimar, Mourad; Mariey, Hervé; Viot, Hervé; Martinot-Lagarde, Gregoire

2016-04-01

Since late 2014, OCA LLR station has been able to range with infrared wavelength (1064nm). IR ranging provides both temporal and spatial improvement in the LLR observations. IR detection also permits in densification of normal points, including the L1 and L2 retroreflectors due to better signal to noise ratio. This contributes to a better modelisation of the lunar libration. The hypothesis of lunar dust and environmental effects due to the chromatic behavior noticed on returns from L2 retroreflector is discussed. In addition, data analysis shows that the effect of retroreflector tilt and the use of calibration profile for the normal point deduction algorithm, contributes to improving the precision of normal points, thereby impacting lunar dynamical models and inner physics.

A hybrid symplectic principal component analysis and central tendency measure method for detection of determinism in noisy time series with application to mechanomyography

NASA Astrophysics Data System (ADS)

Xie, Hong-Bo; Dokos, Socrates

2013-06-01

We present a hybrid symplectic geometry and central tendency measure (CTM) method for detection of determinism in noisy time series. CTM is effective for detecting determinism in short time series and has been applied in many areas of nonlinear analysis. However, its performance significantly degrades in the presence of strong noise. In order to circumvent this difficulty, we propose to use symplectic principal component analysis (SPCA), a new chaotic signal de-noising method, as the first step to recover the system dynamics. CTM is then applied to determine whether the time series arises from a stochastic process or has a deterministic component. Results from numerical experiments, ranging from six benchmark deterministic models to 1/f noise, suggest that the hybrid method can significantly improve detection of determinism in noisy time series by about 20 dB when the data are contaminated by Gaussian noise. Furthermore, we apply our algorithm to study the mechanomyographic (MMG) signals arising from contraction of human skeletal muscle. Results obtained from the hybrid symplectic principal component analysis and central tendency measure demonstrate that the skeletal muscle motor unit dynamics can indeed be deterministic, in agreement with previous studies. However, the conventional CTM method was not able to definitely detect the underlying deterministic dynamics. This result on MMG signal analysis is helpful in understanding neuromuscular control mechanisms and developing MMG-based engineering control applications.

A hybrid symplectic principal component analysis and central tendency measure method for detection of determinism in noisy time series with application to mechanomyography.

PubMed

Xie, Hong-Bo; Dokos, Socrates

2013-06-01

We present a hybrid symplectic geometry and central tendency measure (CTM) method for detection of determinism in noisy time series. CTM is effective for detecting determinism in short time series and has been applied in many areas of nonlinear analysis. However, its performance significantly degrades in the presence of strong noise. In order to circumvent this difficulty, we propose to use symplectic principal component analysis (SPCA), a new chaotic signal de-noising method, as the first step to recover the system dynamics. CTM is then applied to determine whether the time series arises from a stochastic process or has a deterministic component. Results from numerical experiments, ranging from six benchmark deterministic models to 1/f noise, suggest that the hybrid method can significantly improve detection of determinism in noisy time series by about 20 dB when the data are contaminated by Gaussian noise. Furthermore, we apply our algorithm to study the mechanomyographic (MMG) signals arising from contraction of human skeletal muscle. Results obtained from the hybrid symplectic principal component analysis and central tendency measure demonstrate that the skeletal muscle motor unit dynamics can indeed be deterministic, in agreement with previous studies. However, the conventional CTM method was not able to definitely detect the underlying deterministic dynamics. This result on MMG signal analysis is helpful in understanding neuromuscular control mechanisms and developing MMG-based engineering control applications.

Radiation detection method and system using the sequential probability ratio test

DOEpatents

Nelson, Karl E [Livermore, CA; Valentine, John D [Redwood City, CA; Beauchamp, Brock R [San Ramon, CA

2007-07-17

A method and system using the Sequential Probability Ratio Test to enhance the detection of an elevated level of radiation, by determining whether a set of observations are consistent with a specified model within a given bounds of statistical significance. In particular, the SPRT is used in the present invention to maximize the range of detection, by providing processing mechanisms for estimating the dynamic background radiation, adjusting the models to reflect the amount of background knowledge at the current point in time, analyzing the current sample using the models to determine statistical significance, and determining when the sample has returned to the expected background conditions.

Nonlinear convective pulsation models of type II Cepheids

NASA Astrophysics Data System (ADS)

Smolec, Radoslaw

2015-08-01

We present a grid of nonlinear convective pulsation models of type-II Cepheids: BL Her stars, W Vir stars and RV Tau stars. The models cover a wide range of masses, luminosities, effective temperatures and chemical compositions. The most interesting result is detection of deterministic chaos in the models. Different routes to chaos are detected (period doubling, intermittent route) as well as variety of phenomena intrinsic to chaotic dynamics (periodic islands within chaotic bands, crisis bifurcation, type-I and type-III intermittency). Some of the phenomena (period doubling in BL Her and in RV Tau stars, irregular pulsation of RV Tau stars) are well known in the pulsation of type-II Cepheids. Prospects of discovering the other are briefly discussed. Transition from BL Her type pulsation through W Vir type till RV Tau type is analysed. In the most luminous models a dynamical instability is detected, which indicates that pulsation driven mass loss is important process occurring in type-II Cepheids.

Infrared Emission from Kilonovae: The Case of the Nearby Short Hard Burst GRB 160821B

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

Kasliwal, Mansi M.; Lau, Ryan M.; Korobkin, Oleg

We present constraints on Ks-band emission from one of the nearest short hard gamma-ray bursts, GRB 160821B, at z = 0.16, at three epochs. We detect a red relativistic afterglow from the jetted emission in the first epoch but do not detect any excess kilonova emission in the second two epochs. We compare upper limits obtained with Keck I/MOSFIRE to multi-dimensional radiative transfer models of kilonovae, that employ composition-dependent nuclear heating and LTE opacities of heavy elements. We discuss eight models that combine toroidal dynamical ejecta and two types of wind and one model with dynamical ejecta only. We alsomore » discuss simple, empirical scaling laws of predicted emission as a function of ejecta mass and ejecta velocity. Our limits for GRB 160821B constrain the ejecta mass to be lower than 0.03 M {sub ⊙} for velocities greater than 0.1 c. At the distance sensitivity range of advanced LIGO, similar ground-based observations would be sufficiently sensitive to the full range of predicted model emission including models with only dynamical ejecta. The color evolution of these models shows that I – K color spans 7–16 mag, which suggests that even relatively shallow infrared searches for kilonovae could be as constraining as optical searches.« less

Infrared Emission from Kilonovae: The Case of the Nearby Short Hard Burst GRB 160821B

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

Kasliwal, Mansi M.; Korobkin, Oleg; Lau, Ryan M.

In this paper, we present constraints on Ks-band emission from one of the nearest short hard gamma-ray bursts, GRB 160821B, at z = 0.16, at three epochs. We detect a red relativistic afterglow from the jetted emission in the first epoch but do not detect any excess kilonova emission in the second two epochs. We compare upper limits obtained with Keck I/MOSFIRE to multi-dimensional radiative transfer models of kilonovae, that employ composition-dependent nuclear heating and LTE opacities of heavy elements. We discuss eight models that combine toroidal dynamical ejecta and two types of wind and one model with dynamical ejectamore » only. We also discuss simple, empirical scaling laws of predicted emission as a function of ejecta mass and ejecta velocity. Our limits for GRB 160821B constrain the ejecta mass to be lower than 0.03 M ⊙ for velocities greater than 0.1 c. At the distance sensitivity range of advanced LIGO, similar ground-based observations would be sufficiently sensitive to the full range of predicted model emission including models with only dynamical ejecta. Finally, the color evolution of these models shows that I–K color spans 7–16 mag, which suggests that even relatively shallow infrared searches for kilonovae could be as constraining as optical searches.« less

Infrared Emission from Kilonovae: The Case of the Nearby Short Hard Burst GRB 160821B

DOE PAGES

Kasliwal, Mansi M.; Korobkin, Oleg; Lau, Ryan M.; ...

2017-07-12

In this paper, we present constraints on Ks-band emission from one of the nearest short hard gamma-ray bursts, GRB 160821B, at z = 0.16, at three epochs. We detect a red relativistic afterglow from the jetted emission in the first epoch but do not detect any excess kilonova emission in the second two epochs. We compare upper limits obtained with Keck I/MOSFIRE to multi-dimensional radiative transfer models of kilonovae, that employ composition-dependent nuclear heating and LTE opacities of heavy elements. We discuss eight models that combine toroidal dynamical ejecta and two types of wind and one model with dynamical ejectamore » only. We also discuss simple, empirical scaling laws of predicted emission as a function of ejecta mass and ejecta velocity. Our limits for GRB 160821B constrain the ejecta mass to be lower than 0.03 M ⊙ for velocities greater than 0.1 c. At the distance sensitivity range of advanced LIGO, similar ground-based observations would be sufficiently sensitive to the full range of predicted model emission including models with only dynamical ejecta. Finally, the color evolution of these models shows that I–K color spans 7–16 mag, which suggests that even relatively shallow infrared searches for kilonovae could be as constraining as optical searches.« less

76 FR 28214 - UChicago Argonne, LLC, et al.; Notice of Decision on Applications for Duty-Free Entry of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-16

.... Applicant: UChicago Argonne, LLC, Lemont, IL 60439. Instrument: Mythen 1K Detector System. Manufacturer... highly correlated systems. This instrument is unique in that it has a small pixel pitch (50 microns); high detection efficiency, single photon counting with high dynamic range; and a small, lightweight and...

Partial cooperative unfolding in proteins as observed by hydrogen exchange mass spectrometry

PubMed Central

Engen, John R.; Wales, Thomas E.; Chen, Shugui; Marzluff, Elaine M.; Hassell, Kerry M.; Weis, David D.; Smithgall, Thomas E.

2013-01-01

Many proteins do not exist in a single rigid conformation. Protein motions, or dynamics, exist and in many cases are important for protein function. The analysis of protein dynamics relies on biophysical techniques that can distinguish simultaneously existing populations of molecules and their rates of interconversion. Hydrogen exchange (HX) detected by mass spectrometry (MS) is contributing to our understanding of protein motions by revealing unfolding and dynamics on a wide timescale, ranging from seconds to hours to days. In this review we discuss HX MS-based analyses of protein dynamics, using our studies of multi-domain kinases as examples. Using HX MS, we have successfully probed protein dynamics and unfolding in the isolated SH3, SH2 and kinase domains of the c-Src and Abl kinase families, as well as the role of inter- and intra-molecular interactions in the global control of kinase function. Coupled with high-resolution structural information, HX MS has proved to be a powerful and versatile tool for the analysis of the conformational dynamics in these kinase systems, and has provided fresh insight regarding the regulatory control of these important signaling proteins. HX MS studies of dynamics are applicable not only to the proteins we illustrate here, but to a very wide range of proteins and protein systems, and should play a role in both classification of and greater understanding of the prevalence of protein motion. PMID:23682200

Automated detection and recognition of wildlife using thermal cameras.

PubMed

Christiansen, Peter; Steen, Kim Arild; Jørgensen, Rasmus Nyholm; Karstoft, Henrik

2014-07-30

In agricultural mowing operations, thousands of animals are injured or killed each year, due to the increased working widths and speeds of agricultural machinery. Detection and recognition of wildlife within the agricultural fields is important to reduce wildlife mortality and, thereby, promote wildlife-friendly farming. The work presented in this paper contributes to the automated detection and classification of animals in thermal imaging. The methods and results are based on top-view images taken manually from a lift to motivate work towards unmanned aerial vehicle-based detection and recognition. Hot objects are detected based on a threshold dynamically adjusted to each frame. For the classification of animals, we propose a novel thermal feature extraction algorithm. For each detected object, a thermal signature is calculated using morphological operations. The thermal signature describes heat characteristics of objects and is partly invariant to translation, rotation, scale and posture. The discrete cosine transform (DCT) is used to parameterize the thermal signature and, thereby, calculate a feature vector, which is used for subsequent classification. Using a k-nearest-neighbor (kNN) classifier, animals are discriminated from non-animals with a balanced classification accuracy of 84.7% in an altitude range of 3-10 m and an accuracy of 75.2% for an altitude range of 10-20 m. To incorporate temporal information in the classification, a tracking algorithm is proposed. Using temporal information improves the balanced classification accuracy to 93.3% in an altitude range 3-10 of meters and 77.7% in an altitude range of 10-20 m.

Spectroelectrochemical detection of microRNA-155 based on functional RNA immobilization onto ITO/GNP nanopattern.

PubMed

Mohammadniaei, Mohsen; Yoon, Jinho; Lee, Taek; Choi, Jeong-Woo

2018-05-20

We fabricated a microRNA biosensor using the combination of surface enhanced Raman spectroscopy (SERS) and electrochemical (EC) techniques. For the first time, the weaknesses of each techniques for microRNA detection was compensated by the other ones to give rise to the specific and wide-range detection of miR-155. A single stranded 3' methylene blue (MB) and 5' thiol-modified RNA (MB-ssRNA-SH) was designed to detect the target miR-155 and immobilized onto the gold nanoparticle-modified ITO (ITO/GNP). Upon the invasion of target strand, the double-stranded RNA transformed rapidly to an upright structure resulting in a notable decrease in SERS and redox signals of the MB. For the first time, by combination of SERS and EC techniques in a single platform we extended the dynamic range of both techniques from 10 pM to 450 nM (SERS: 10 pM-5 nM and EC: 5 nM-450 nM). As well, the SERS technique improved the detection limit of the EC method from 100 pM to 100 fM, while the EC method covered single-mismatch detection which was the SERS deficiency. The fabricated single-step biosensor possessing a good capability of miRNA detection in human serum, could be employed throughout the broad ranges of biomedical and bioelectronics applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Rapid chromatographic determination of caseins in milk with photometric and fluorimetric detection using a hydrophobic monolithic column.

PubMed

Ramírez-Palomino, P; Fernández-Romero, J M; Gómez-Hens, A

2014-01-01

Reverse-phase liquid chromatographic methods using a hydrophobic C18 monolithic column and on-line photometric and fluorimetric detection for the determination of the major casein (CN) proteins in milk are presented. The separation of αs1-CN, αs2-CN, β-CN and κ-CN was achieved in only five minutes. Fluorimetric detection enabled better analytical results than photometric detection. Thus, the dynamic ranges of the calibration graphs and detection limits obtained using fluorimetric detection were (mgmL(-)(1)): αs1-CN (0.74-10.0, 0.22), αs2-CN (0.15-10.0, 0.045), β-CN (0.68-10.0, 0.20) and κ-CN (0.21-10.0, 0.06). The analytical features of the photometric method, which does not allow the quantification of β-casein, were (mgmL(-)(1)): αs1-CN (1.5-9.0, 0.45), αs2-CN (1.4-10.0, 0.43) and κ-CN (0.4-9.0, 0.12). Precision data, expressed as relative standard deviation, ranged between 0.6% and 5.3% for the fluorimetric method and between 2.4% and 6.2% for the photometric method. Both methods were applied to the analysis of three different milk samples, obtaining recoveries in the ranges of 86.6-103.2% and 92.0-106.5% using fluorimetric and photometric detection, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

SQUID-detected FMR: Resonance in single crystalline and polycrystalline yttrium iron garnet

NASA Astrophysics Data System (ADS)

O'Reilly, J. M.; Stamenov, P.

2018-04-01

Here two new techniques for the detection of broadband (100 MHz-20 GHz) ferromagnetic resonance (FMR)/ferrimagnetic resonance in single and poly-crystalline materials, which rely on SQUID-based gradiometry detection of small changes in the magnetisation, are developed. In the first method, small changes in the along-the-applied-field projection of the coupled magnetic moment (Δmz) are detected as the material is driven into resonance. Absolute measurement of the longitudinal component of the magnetisation and the resonance induced lowering of this moment makes estimation of the precession cone angle accessible, which is typically difficult to extract using conventional cavity or stripline based detection methods. The second method invokes the change in Δmz with the resonance-induced thermal heating (d/mz d T ). Magnetisation dynamics in bulk Y3Fe5O12 are observed over a broad range of experimental temperatures (4 K-400 K) and fields (10-500 mT). The inhomogeneous microwave excitation allows for the observation of higher magnetostatic modes and the convenient tracking of very broad resonances. The two SQUID-detection techniques when combined with conventional broadband vector network analyser-FMR, low-frequency magnetic susceptibility, and DC magnetometry, all easily realised, essentially concurrently, using the same module, greatly expand the amount of static and dynamic information accessible.

Large-Scale Test of Dynamic Correlation Processors: Implications for Correlation-Based Seismic Pipelines

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

Dodge, D. A.; Harris, D. B.

Correlation detectors are of considerable interest to the seismic monitoring communities because they offer reduced detection thresholds and combine detection, location and identification functions into a single operation. They appear to be ideal for applications requiring screening of frequent repeating events. However, questions remain about how broadly empirical correlation methods are applicable. We describe the effectiveness of banks of correlation detectors in a system that combines traditional power detectors with correlation detectors in terms of efficiency, which we define to be the fraction of events detected by the correlators. This paper elaborates and extends the concept of a dynamic correlationmore » detection framework – a system which autonomously creates correlation detectors from event waveforms detected by power detectors; and reports observed performance on a network of arrays in terms of efficiency. We performed a large scale test of dynamic correlation processors on an 11 terabyte global dataset using 25 arrays in the single frequency band 1-3 Hz. The system found over 3.2 million unique signals and produced 459,747 screened detections. A very satisfying result is that, on average, efficiency grows with time and, after nearly 16 years of operation, exceeds 47% for events observed over all distance ranges and approaches 70% for near regional and 90% for local events. This observation suggests that future pipeline architectures should make extensive use of correlation detectors, principally for decluttering observations of local and near-regional events. Our results also suggest that future operations based on correlation detection will require commodity large-scale computing infrastructure, since the numbers of correlators in an autonomous system can grow into the hundreds of thousands.« less

Large-Scale Test of Dynamic Correlation Processors: Implications for Correlation-Based Seismic Pipelines

DOE PAGES

Dodge, D. A.; Harris, D. B.

2016-03-15

Correlation detectors are of considerable interest to the seismic monitoring communities because they offer reduced detection thresholds and combine detection, location and identification functions into a single operation. They appear to be ideal for applications requiring screening of frequent repeating events. However, questions remain about how broadly empirical correlation methods are applicable. We describe the effectiveness of banks of correlation detectors in a system that combines traditional power detectors with correlation detectors in terms of efficiency, which we define to be the fraction of events detected by the correlators. This paper elaborates and extends the concept of a dynamic correlationmore » detection framework – a system which autonomously creates correlation detectors from event waveforms detected by power detectors; and reports observed performance on a network of arrays in terms of efficiency. We performed a large scale test of dynamic correlation processors on an 11 terabyte global dataset using 25 arrays in the single frequency band 1-3 Hz. The system found over 3.2 million unique signals and produced 459,747 screened detections. A very satisfying result is that, on average, efficiency grows with time and, after nearly 16 years of operation, exceeds 47% for events observed over all distance ranges and approaches 70% for near regional and 90% for local events. This observation suggests that future pipeline architectures should make extensive use of correlation detectors, principally for decluttering observations of local and near-regional events. Our results also suggest that future operations based on correlation detection will require commodity large-scale computing infrastructure, since the numbers of correlators in an autonomous system can grow into the hundreds of thousands.« less

Elaborately designed diblock nanoprobes for simultaneous multicolor detection of microRNAs

NASA Astrophysics Data System (ADS)

Wang, Chenguang; Zhang, Huan; Zeng, Dongdong; Sun, Wenliang; Zhang, Honglu; Aldalbahi, Ali; Wang, Yunsheng; San, Lili; Fan, Chunhai; Zuo, Xiaolei; Mi, Xianqiang

2015-09-01

Simultaneous detection of multiple biomarkers has important prospects in the biomedical field. In this work, we demonstrated a novel strategy for the detection of multiple microRNAs (miRNAs) based on gold nanoparticles (Au NPs) and polyadenine (polyA) mediated nanoscale molecular beacon (MB) probes (denoted p-nanoMBs). Novel fluorescent labeled p-nanoMBs bearing consecutive adenines were designed, of which polyA served as an effective anchoring block binding to the surface of Au NPs, and the appended hairpin block formed an upright conformation that favored the hybridization with targets. Using the co-assembling method and the improved hybridization conformation of the hairpin probes, we achieved high selectivity for specifically distinguishing DNA targets from single-base mismatched DNA targets. We also realized multicolor detection of three different synthetic miRNAs in a wide dynamic range from 0.01 nM to 200 nM with a detection limit of 10 pM. What's more, we even detected miRNAs in a simulated serum environment, which indicated that our method could be used in complex media. Compared with the traditional method, our strategy provides a promising alternative method for the qualitative and quantitative detection of miRNAs.Simultaneous detection of multiple biomarkers has important prospects in the biomedical field. In this work, we demonstrated a novel strategy for the detection of multiple microRNAs (miRNAs) based on gold nanoparticles (Au NPs) and polyadenine (polyA) mediated nanoscale molecular beacon (MB) probes (denoted p-nanoMBs). Novel fluorescent labeled p-nanoMBs bearing consecutive adenines were designed, of which polyA served as an effective anchoring block binding to the surface of Au NPs, and the appended hairpin block formed an upright conformation that favored the hybridization with targets. Using the co-assembling method and the improved hybridization conformation of the hairpin probes, we achieved high selectivity for specifically distinguishing DNA targets from single-base mismatched DNA targets. We also realized multicolor detection of three different synthetic miRNAs in a wide dynamic range from 0.01 nM to 200 nM with a detection limit of 10 pM. What's more, we even detected miRNAs in a simulated serum environment, which indicated that our method could be used in complex media. Compared with the traditional method, our strategy provides a promising alternative method for the qualitative and quantitative detection of miRNAs. Electronic supplementary information (ESI) available: Sequences for oligonucleotides used for this work, dynamic light scattering (DLS) measurements, fluorescent signal intensity with different ratios between p-MBs and A5 oligonucleotides, quantification of the fluorescent p-MB, and UV-Vis spectra for naked AuNPs and the p-nanoMB. See DOI: 10.1039/c5nr04618a

A one-dimensional free energy surface does not account for two-probe folding kinetics of protein alpha(3)D.

PubMed

Liu, Feng; Dumont, Charles; Zhu, Yongjin; DeGrado, William F; Gai, Feng; Gruebele, Martin

2009-02-14

We present fluorescence-detected measurements of the temperature-jump relaxation kinetics of the designed three-helix bundle protein alpha(3)D taken under solvent conditions identical to previous infrared-detected kinetics. The fluorescence-detected rate is similar to the IR-detected rate only at the lowest temperature where we could measure it (326 K). The fluorescence-detected rate decreases by a factor of 3 over the 326-344 K temperature range, whereas the IR-detected rate remains nearly constant over the same range. To investigate this probe dependence, we tested an extensive set of physically reasonable one-dimensional (1D) free energy surfaces by Langevin dynamics simulation. The simulations included coordinate- and temperature-dependent roughness, diffusion coefficients, and IR/fluorescence spectroscopic signatures. None of these can reproduce the IR and fluorescence data simultaneously, forcing us to the conclusion that a 1D free energy surface cannot accurately describe the folding of alpha(3)D. This supports the hypothesis that alpha(3)D has a multidimensional free energy surface conducive to downhill folding at 326 K, and that it is already an incipient downhill folder with probe-dependent kinetics near its melting point.

The EIGER detector for low-energy electron microscopy and photoemission electron microscopy.

PubMed

Tinti, G; Marchetto, H; Vaz, C A F; Kleibert, A; Andrä, M; Barten, R; Bergamaschi, A; Brückner, M; Cartier, S; Dinapoli, R; Franz, T; Fröjdh, E; Greiffenberg, D; Lopez-Cuenca, C; Mezza, D; Mozzanica, A; Nolting, F; Ramilli, M; Redford, S; Ruat, M; Ruder, Ch; Schädler, L; Schmidt, Th; Schmitt, B; Schütz, F; Shi, X; Thattil, D; Vetter, S; Zhang, J

2017-09-01

EIGER is a single-photon-counting hybrid pixel detector developed at the Paul Scherrer Institut, Switzerland. It is designed for applications at synchrotron light sources with photon energies above 5 keV. Features of EIGER include a small pixel size (75 µm × 75 µm), a high frame rate (up to 23 kHz), a small dead-time between frames (down to 3 µs) and a dynamic range up to 32-bit. In this article, the use of EIGER as a detector for electrons in low-energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM) is reported. It is demonstrated that, with only a minimal modification to the sensitive part of the detector, EIGER is able to detect electrons emitted or reflected by the sample and accelerated to 8-20 keV. The imaging capabilities are shown to be superior to the standard microchannel plate detector for these types of applications. This is due to the much higher signal-to-noise ratio, better homogeneity and improved dynamic range. In addition, the operation of the EIGER detector is not affected by radiation damage from electrons in the present energy range and guarantees more stable performance over time. To benchmark the detector capabilities, LEEM experiments are performed on selected surfaces and the magnetic and electronic properties of individual iron nanoparticles with sizes ranging from 8 to 22 nm are detected using the PEEM endstation at the Surface/Interface Microscopy (SIM) beamline of the Swiss Light Source.

Deformable mirror-based optical design of dynamic local athermal longwave infrared optical systems

NASA Astrophysics Data System (ADS)

Shen, Benlan; Chang, Jun; Niu, Yajun; Chen, Weilin; Ji, Zhongye

2018-07-01

This paper presents a dynamic local athermalisation method for longwave infrared (LWIR) optical systems; the proposed design uses a deformable mirror and is based on active optics theory. A local athermal LWIR optical system is designed as an example. The deformable mirror is tilted by 45° near the exit pupil of the system. The thermal aberrations are corrected by the deformable mirror for the local athermal field of view (FOV) that ranges from -40 °C to 80 °C. The types of thermal aberrations are analysed. Simulated results show that the local athermal LWIR optical system can effectively detect targets in the region of interest within a large FOV and correct thermal aberrations in actual working environments in real time. The system has numerous potential applications in infrared detection and tracking, surveillance and remote sensing.

Event detection and localization for small mobile robots using reservoir computing.

PubMed

Antonelo, E A; Schrauwen, B; Stroobandt, D

2008-08-01

Reservoir Computing (RC) techniques use a fixed (usually randomly created) recurrent neural network, or more generally any dynamic system, which operates at the edge of stability, where only a linear static readout output layer is trained by standard linear regression methods. In this work, RC is used for detecting complex events in autonomous robot navigation. This can be extended to robot localization tasks which are solely based on a few low-range, high-noise sensory data. The robot thus builds an implicit map of the environment (after learning) that is used for efficient localization by simply processing the input stream of distance sensors. These techniques are demonstrated in both a simple simulation environment and in the physically realistic Webots simulation of the commercially available e-puck robot, using several complex and even dynamic environments.

Radiometric calibration method for large aperture infrared system with broad dynamic range.

PubMed

Sun, Zhiyuan; Chang, Songtao; Zhu, Wei

2015-05-20

Infrared radiometric measurements can acquire important data for missile defense systems. When observation is carried out by ground-based infrared systems, a missile is characterized by long distance, small size, and large variation of radiance. Therefore, the infrared systems should be manufactured with a larger aperture to enhance detection ability and calibrated at a broader dynamic range to extend measurable radiance. Nevertheless, the frequently used calibration methods demand an extended-area blackbody with broad dynamic range or a huge collimator for filling the system's field stop, which would greatly increase manufacturing costs and difficulties. To overcome this restriction, a calibration method based on amendment of inner and outer calibration is proposed. First, the principles and procedures of this method are introduced. Then, a shifting strategy of infrared systems for measuring targets with large fluctuations of infrared radiance is put forward. Finally, several experiments are performed on a shortwave infrared system with Φ400  mm aperture. The results indicate that the proposed method cannot only ensure accuracy of calibration but have the advantage of low cost, low power, and high motility. Hence, it is an effective radiometric calibration method in the outfield.

Wavelength-Scanning SPR Imaging Sensors Based on an Acousto-Optic Tunable Filter and a White Light Laser

PubMed Central

Zeng, Youjun; Wang, Lei; Wu, Shu-Yuen; He, Jianan; Qu, Junle; Li, Xuejin; Ho, Ho-Pui; Gu, Dayong; Gao, Bruce Zhi; Shao, Yonghong

2017-01-01

A fast surface plasmon resonance (SPR) imaging biosensor system based on wavelength interrogation using an acousto-optic tunable filter (AOTF) and a white light laser is presented. The system combines the merits of a wide-dynamic detection range and high sensitivity offered by the spectral approach with multiplexed high-throughput data collection and a two-dimensional (2D) biosensor array. The key feature is the use of AOTF to realize wavelength scan from a white laser source and thus to achieve fast tracking of the SPR dip movement caused by target molecules binding to the sensor surface. Experimental results show that the system is capable of completing a SPR dip measurement within 0.35 s. To the best of our knowledge, this is the fastest time ever reported in the literature for imaging spectral interrogation. Based on a spectral window with a width of approximately 100 nm, a dynamic detection range and resolution of 4.63 × 10−2 refractive index unit (RIU) and 1.27 × 10−6 RIU achieved in a 2D-array sensor is reported here. The spectral SPR imaging sensor scheme has the capability of performing fast high-throughput detection of biomolecular interactions from 2D sensor arrays. The design has no mechanical moving parts, thus making the scheme completely solid-state. PMID:28067766

Fully automated, internally controlled quantification of hepatitis B Virus DNA by real-time PCR by use of the MagNA Pure LC and LightCycler instruments.

PubMed

Leb, Victoria; Stöcher, Markus; Valentine-Thon, Elizabeth; Hölzl, Gabriele; Kessler, Harald; Stekel, Herbert; Berg, Jörg

2004-02-01

We report on the development of a fully automated real-time PCR assay for the quantitative detection of hepatitis B virus (HBV) DNA in plasma with EDTA (EDTA plasma). The MagNA Pure LC instrument was used for automated DNA purification and automated preparation of PCR mixtures. Real-time PCR was performed on the LightCycler instrument. An internal amplification control was devised as a PCR competitor and was introduced into the assay at the stage of DNA purification to permit monitoring for sample adequacy. The detection limit of the assay was found to be 200 HBV DNA copies/ml, with a linear dynamic range of 8 orders of magnitude. When samples from the European Union Quality Control Concerted Action HBV Proficiency Panel 1999 were examined, the results were found to be in acceptable agreement with the HBV DNA concentrations of the panel members. In a clinical laboratory evaluation of 123 EDTA plasma samples, a significant correlation was found with the results obtained by the Roche HBV Monitor test on the Cobas Amplicor analyzer within the dynamic range of that system. In conclusion, the newly developed assay has a markedly reduced hands-on time, permits monitoring for sample adequacy, and is suitable for the quantitative detection of HBV DNA in plasma in a routine clinical laboratory.

A three-wavelength multi-channel brain functional imager based on digital lock-in photon-counting technique

NASA Astrophysics Data System (ADS)

Ding, Xuemei; Wang, Bingyuan; Liu, Dongyuan; Zhang, Yao; He, Jie; Zhao, Huijuan; Gao, Feng

2018-02-01

During the past two decades there has been a dramatic rise in the use of functional near-infrared spectroscopy (fNIRS) as a neuroimaging technique in cognitive neuroscience research. Diffuse optical tomography (DOT) and optical topography (OT) can be employed as the optical imaging techniques for brain activity investigation. However, most current imagers with analogue detection are limited by sensitivity and dynamic range. Although photon-counting detection can significantly improve detection sensitivity, the intrinsic nature of sequential excitations reduces temporal resolution. To improve temporal resolution, sensitivity and dynamic range, we develop a multi-channel continuous-wave (CW) system for brain functional imaging based on a novel lock-in photon-counting technique. The system consists of 60 Light-emitting device (LED) sources at three wavelengths of 660nm, 780nm and 830nm, which are modulated by current-stabilized square-wave signals at different frequencies, and 12 photomultiplier tubes (PMT) based on lock-in photon-counting technique. This design combines the ultra-high sensitivity of the photon-counting technique with the parallelism of the digital lock-in technique. We can therefore acquire the diffused light intensity for all the source-detector pairs (SD-pairs) in parallel. The performance assessments of the system are conducted using phantom experiments, and demonstrate its excellent measurement linearity, negligible inter-channel crosstalk, strong noise robustness and high temporal resolution.

A Fiber Bragg Grating-Based Dynamic Tension Detection System for Overhead Transmission Line Galloping.

PubMed

Ma, Guo-Ming; Li, Ya-Bo; Mao, Nai-Qiang; Shi, Cheng; Zhang, Bo; Li, Cheng-Rong

2018-01-26

Galloping of overhead transmission lines (OHTLs) may induce conductor breakage and tower collapse, and there is no effective method for long distance distribution on-line galloping monitoring. To overcome the drawbacks of the conventional galloping monitoring systems, such as sensitivity to electromagnetic interference, the need for onsite power, and short lifetimes, a novel optical remote passive measuring system is proposed in the paper. Firstly, to solve the hysteresis and eccentric load problem in tension sensing, and to extent the dynamic response range, an 'S' type elastic element structure with flanges was proposed. Then, a tension experiment was carried out to demonstrate the dynamic response characteristics. Moreover, the designed tension sensor was stretched continuously for 30 min to observe its long time stability. Last but not the least, the sensor was mounted on a 70 m conductor model, and the conductor was oscillated at different frequencies to investigate the dynamic performance of the sensor. The experimental results demonstrate the sensor is suitable for the OHTL galloping detection. Compared with the conventional sensors for OHTL monitoring, the system has many advantages, such as easy installation, no flashover risk, distribution monitoring, better bandwidth, improved accuracy and higher reliability.

Comparative Evaluation of Four Real-Time PCR Methods for the Quantitative Detection of Epstein-Barr Virus from Whole Blood Specimens.

PubMed

Buelow, Daelynn; Sun, Yilun; Tang, Li; Gu, Zhengming; Pounds, Stanley; Hayden, Randall

2016-07-01

Monitoring of Epstein-Barr virus (EBV) load in immunocompromised patients has become integral to their care. An increasing number of reagents are available for quantitative detection of EBV; however, there are little published comparative data. Four real-time PCR systems (one using laboratory-developed reagents and three using analyte-specific reagents) were compared with one another for detection of EBV from whole blood. Whole blood specimens seeded with EBV were used to determine quantitative linearity, analytical measurement range, lower limit of detection, and CV for each assay. Retrospective testing of 198 clinical samples was performed in parallel with all methods; results were compared to determine relative quantitative and qualitative performance. All assays showed similar performance. No significant difference was found in limit of detection (3.12-3.49 log10 copies/mL; P = 0.37). A strong qualitative correlation was seen with all assays that used clinical samples (positive detection rates of 89.5%-95.8%). Quantitative correlation of clinical samples across assays was also seen in pairwise regression analysis, with R(2) ranging from 0.83 to 0.95. Normalizing clinical sample results to IU/mL did not alter the quantitative correlation between assays. Quantitative EBV detection by real-time PCR can be performed over a wide linear dynamic range, using three different commercially available reagents and laboratory-developed methods. EBV was detected with comparable sensitivity and quantitative correlation for all assays. Copyright © 2016 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.

Detection of Ionic liquid using terahertz time-domain spectroscopy

NASA Astrophysics Data System (ADS)

Wang, Cuicui; Zhao, Xiaojing; Liu, Shangjian; Zuo, Jian; Zhang, Cunlin

2018-01-01

Terahertz (THz, THz+1012Hz) spectroscopy is a far-infrared analytical technology with spectral bands locating between microware and infrared ranges. Being of excellent transmission, non-destruction and high discrimination, this technology has been applied in various fields such as physics, chemistry, nondestructive detection, communication, biomedicine public security. Terahertz spectrum is corresponding with vibration and rotation of liquid molecules, which is suitable to identify and study the liquid molecular dynamics. It is as a powerful spectral detection technology, terahertz time-domain spectroscopy is widely used in solution detection. can enable us to extract the material parameters or dielectric spectrum that show material micro-structure and dynamics by measuring amplitude and phase from coherent terahertz pulses. Ionic liquid exists in most biological tissues, and it is very important for life. It has recently been suggested that near-fired terahertz ionic contrast microscopy can be employed to image subtle changes in ionic concentrations arising from neuronal activity. In this paper, we detected Ionic liquid with different concentrations at room temperature by THz-TDS technique in the range of 0.2-1.5 THz. The liquid cell with a thickness of 0.2mm is made of quartz. The absorption coefficient, refractive index and dielectric function of solutions can be extracted based on THz-TDS. We use an expanded model for fitting the dielectric function based on a combination of a Debye relation for the anions and cations. We find A linear increase of the real and imaginary part of the dielectric function compared with pure water with increasing ion concentrations. A good agreement between the model and the experimental results is obtained. By means of dielectric relaxation process, it was found that the characteristic time of molecular movement and the information related to the liquid molecular structure and movement was obtained.

Rapid detection of the neonicotinoid insecticide imidacloprid using a quenchbody assay.

PubMed

Zhao, Shitao; Dong, Jinhua; Jeong, Hee-Jin; Okumura, Koichi; Ueda, Hiroshi

2018-04-28

Contamination of the land and water by neonicotinoid insecticide residues is currently a severe environmental problem. However, the traditional methods for pesticide residue analysis are time consuming and laborious. To tackle this problem, here we describe a novel quenchbody (Q-body) immunoassay reagent that allows the rapid and sensitive detection of imidacloprid, one of the most frequently used neonicotinoid pesticides, in aqueous solution. A Q-body comprises an antibody Fab fragment that is site-specifically labeled with a fluorescent dye. The Fab fragment quenches the dye with its internal tryptophan residues via photoinduced electron transfer. The subsequent addition of imidacloprid stabilizes the antibody structure and displaces the quenched dye to the outside of the protein, resulting in increased fluorescence. The constructed Q-body assay exhibited a high dynamic range and a low limit of detection (10 ng mL -1 ), and the entire assay procedure could be completed in a few minutes. The assay showed a low cross-reactivity with possible interfering analogous compounds, indicating that it has a good selectivity. Hence, the developed Q-body assay has excellent potential as a universal technology for monitoring neonicotinoid residues in environmental and food samples. Graphical abstract A novel quenchbody (Q-body) immunoassay reagent that allows the rapid and sensitive detection of imidacloprid, one of the most frequently used neonicotinoid pesticides, in aqueous solution was developed. The addition of imidacloprid stabilizes the Q-body structure and displaces the quenched dye to the outside of the protein, resulting in increased fluorescence. The constructed Q-body assay exhibited a high dynamic range and a low limit of detection (10 ng mL -1 ), and completed in a few minutes.

A Nanocoaxial-Based Electrochemical Sensor for the Detection of Cholera Toxin

NASA Astrophysics Data System (ADS)

Archibald, Michelle M.; Rizal, Binod; Connolly, Timothy; Burns, Michael J.; Naughton, Michael J.; Chiles, Thomas C.

2015-03-01

Sensitive, real-time detection of biomarkers is of critical importance for rapid and accurate diagnosis of disease for point of care (POC) technologies. Current methods do not allow for POC applications due to several limitations, including sophisticated instrumentation, high reagent consumption, limited multiplexing capability, and cost. Here, we report a nanocoaxial-based electrochemical sensor for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV). Proof-of-concept was demonstrated for the detection of cholera toxin (CT). The linear dynamic range of detection was 10 ng/ml - 1 μg/ml, and the limit of detection (LOD) was found to be 2 ng/ml. This level of sensitivity is comparable to the standard optical ELISA used widely in clinical applications. In addition to matching the detection profile of the standard ELISA, the nanocoaxial array provides a simple electrochemical readout and a miniaturized platform with multiplexing capabilities for the simultaneous detection of multiple biomarkers, giving the nanocoax a desirable advantage over the standard method towards POC applications. Sensitive, real-time detection of biomarkers is of critical importance for rapid and accurate diagnosis of disease for point of care (POC) technologies. Current methods do not allow for POC applications due to several limitations, including sophisticated instrumentation, high reagent consumption, limited multiplexing capability, and cost. Here, we report a nanocoaxial-based electrochemical sensor for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV). Proof-of-concept was demonstrated for the detection of cholera toxin (CT). The linear dynamic range of detection was 10 ng/ml - 1 μg/ml, and the limit of detection (LOD) was found to be 2 ng/ml. This level of sensitivity is comparable to the standard optical ELISA used widely in clinical applications. In addition to matching the detection profile of the standard ELISA, the nanocoaxial array provides a simple electrochemical readout and a miniaturized platform with multiplexing capabilities for the simultaneous detection of multiple biomarkers, giving the nanocoax a desirable advantage over the standard method towards POC applications. This work was supported by the National Institutes of Health (National Cancer Institute award No. CA137681 and National Institute of Allergy and Infectious Diseases Award No. AI100216).

High-order synchronization of hair cell bundles

NASA Astrophysics Data System (ADS)

Levy, Michael; Molzon, Adrian; Lee, Jae-Hyun; Kim, Ji-Wook; Cheon, Jinwoo; Bozovic, Dolores

2016-12-01

Auditory and vestibular hair cell bundles exhibit active mechanical oscillations at natural frequencies that are typically lower than the detection range of the corresponding end organs. We explore how these noisy nonlinear oscillators mode-lock to frequencies higher than their internal clocks. A nanomagnetic technique is used to stimulate the bundles without an imposed mechanical load. The evoked response shows regimes of high-order mode-locking. Exploring a broad range of stimulus frequencies and intensities, we observe regions of high-order synchronization, analogous to Arnold Tongues in dynamical systems literature. Significant areas of overlap occur between synchronization regimes, with the bundle intermittently flickering between different winding numbers. We demonstrate how an ensemble of these noisy spontaneous oscillators could be entrained to efficiently detect signals significantly above the characteristic frequencies of the individual cells.

High-order synchronization of hair cell bundles

PubMed Central

Levy, Michael; Molzon, Adrian; Lee, Jae-Hyun; Kim, Ji-wook; Cheon, Jinwoo; Bozovic, Dolores

2016-01-01

Auditory and vestibular hair cell bundles exhibit active mechanical oscillations at natural frequencies that are typically lower than the detection range of the corresponding end organs. We explore how these noisy nonlinear oscillators mode-lock to frequencies higher than their internal clocks. A nanomagnetic technique is used to stimulate the bundles without an imposed mechanical load. The evoked response shows regimes of high-order mode-locking. Exploring a broad range of stimulus frequencies and intensities, we observe regions of high-order synchronization, analogous to Arnold Tongues in dynamical systems literature. Significant areas of overlap occur between synchronization regimes, with the bundle intermittently flickering between different winding numbers. We demonstrate how an ensemble of these noisy spontaneous oscillators could be entrained to efficiently detect signals significantly above the characteristic frequencies of the individual cells. PMID:27974743

MuSCoWERT: multi-scale consistence of weighted edge Radon transform for horizon detection in maritime images.

PubMed

Prasad, Dilip K; Rajan, Deepu; Rachmawati, Lily; Rajabally, Eshan; Quek, Chai

2016-12-01

This paper addresses the problem of horizon detection, a fundamental process in numerous object detection algorithms, in a maritime environment. The maritime environment is characterized by the absence of fixed features, the presence of numerous linear features in dynamically changing objects and background and constantly varying illumination, rendering the typically simple problem of detecting the horizon a challenging one. We present a novel method called multi-scale consistence of weighted edge Radon transform, abbreviated as MuSCoWERT. It detects the long linear features consistent over multiple scales using multi-scale median filtering of the image followed by Radon transform on a weighted edge map and computing the histogram of the detected linear features. We show that MuSCoWERT has excellent performance, better than seven other contemporary methods, for 84 challenging maritime videos, containing over 33,000 frames, and captured using visible range and near-infrared range sensors mounted onboard, onshore, or on floating buoys. It has a median error of about 2 pixels (less than 0.2%) from the center of the actual horizon and a median angular error of less than 0.4 deg. We are also sharing a new challenging horizon detection dataset of 65 videos of visible, infrared cameras for onshore and onboard ship camera placement.

Deep UV laser-induced fluorescence detection of unlabeled drugs and proteins in microchip electrophoresis.

PubMed

Schulze, Philipp; Ludwig, Martin; Kohler, Frank; Belder, Detlev

2005-03-01

Deep UV fluorescence detection at 266-nm excitation wavelength has been realized for sensitive detection in microchip electrophoresis. For this purpose, an epifluorescence setup was developed enabling the coupling of a deep UV laser into a commercial fluorescence microscope. Deep UV laser excitation utilizing a frequency quadrupled pulsed laser operating at 266 nm shows an impressive performance for native fluorescence detection of various compounds in fused-silica microfluidic devices. Aromatic low molecular weight compounds such as serotonin, propranolol, a diol, and tryptophan could be detected at low-micromolar concentrations. Deep UV fluorescence detection was also successfully employed for the detection of unlabeled basic proteins. For this purpose, fused-silica chips dynamically coated with hydroxypropylmethyl cellulose were employed to suppress analyte adsorption. Utilizing fused-silica chips permanently coated with poly(vinyl alcohol), it was also possible to separate and detect egg white chicken proteins. These data show that deep UV fluorescence detection significantly widens the application range of fluorescence detection in chip-based analysis techniques.

Critical role for cochlear hair cell BK channels for coding the temporal structure and dynamic range of auditory information for central auditory processing

PubMed Central

Kurt, Simone; Sausbier, Matthias; Rüttiger, Lukas; Brandt, Niels; Moeller, Christoph K.; Kindler, Jennifer; Sausbier, Ulrike; Zimmermann, Ulrike; van Straaten, Harald; Neuhuber, Winfried; Engel, Jutta; Knipper, Marlies; Ruth, Peter; Schulze, Holger

2012-01-01

Large conductance, voltage- and Ca2+-activated K+ (BK) channels in inner hair cells (IHCs) of the cochlea are essential for hearing. However, germline deletion of BKα, the pore-forming subunit KCNMA1 of the BK channel, surprisingly did not affect hearing thresholds in the first postnatal weeks, even though altered IHC membrane time constants, decreased IHC receptor potential alternating current/direct current ratio, and impaired spike timing of auditory fibers were reported in these mice. To investigate the role of IHC BK channels for central auditory processing, we generated a conditional mouse model with hair cell-specific deletion of BKα from postnatal day 10 onward. This had an unexpected effect on temporal coding in the central auditory system: neuronal single and multiunit responses in the inferior colliculus showed higher excitability and greater precision of temporal coding that may be linked to the improved discrimination of temporally modulated sounds observed in behavioral training. The higher precision of temporal coding, however, was restricted to slower modulations of sound and reduced stimulus-driven activity. This suggests a diminished dynamic range of stimulus coding that is expected to impair signal detection in noise. Thus, BK channels in IHCs are crucial for central coding of the temporal fine structure of sound and for detection of signals in a noisy environment.—Kurt, S., Sausbier, M., Rüttiger, L., Brandt, N., Moeller, C. K., Kindler, J., Sausbier, U., Zimmermann, U., van Straaten, H., Neuhuber, W., Engel, J., Knipper, M., Ruth, P., Schulze, H. Critical role for cochlear hair cell BK channels for coding the temporal structure and dynamic range of auditory information for central auditory processing. PMID:22691916

Photon spectroscopy by picoseconds differential Geiger-mode Si photomultiplier

NASA Astrophysics Data System (ADS)

Yamamoto, Masanobu; Hernandez, Keegan; Robinson, J. Paul

2018-02-01

The pixel array silicon photomultiplier (SiPM) is known as an excellent photon sensor with picoseconds avalanche process with the capacity for millions amplification of photoelectrons. In addition, a higher quantum efficiency(QE), small size, low bias voltage, light durability are attractive features for biological applications. The primary disadvantage is the limited dynamic range due to the 50ns recharge process and a high dark count which is an additional hurdle. We have developed a wide dynamic Si photon detection system applying ultra-fast differentiation signal processing, temperature control by thermoelectric device and Giga photon counter with 9 decimal digits dynamic range. The tested performance is six orders of magnitude with 600ps pulse width and sub-fW sensitivity. Combined with 405nm laser illumination and motored monochromator, Laser Induced Fluorescence Photon Spectrometry (LIPS) has been developed with a scan range from 200 900nm at maximum of 500nm/sec and 1nm FWHM. Based on the Planck equation E=hν, this photon counting spectrum provides a fundamental advance in spectral analysis by digital processing. Advantages include its ultimate sensitivity, theoretical linearity, as well as quantitative and logarithmic analysis without use of arbitrary units. Laser excitation is also useful for evaluation of photobleaching or oxidation in materials by higher energy illumination. Traditional typical photocurrent detection limit is about 1pW which includes millions of photons, however using our system it is possible to evaluate the photon spectrum and determine background noise and auto fluorescence(AFL) in optics in any cytometry or imaging system component. In addition, the photon-stream digital signal opens up a new approach for picosecond time-domain analysis. Photon spectroscopy is a powerful method for analysis of fluorescence and optical properties in biology.

A high-speed fiber optic data bus for local data communications

NASA Astrophysics Data System (ADS)

Porter, D. R.; Couch, P. R.; Schelin, J. W.

1983-04-01

A 100 Mbit/s fiber optic data bus is described which is capable of inter-connecting up to 16 terminals by means of a passive optical star coupler for terminal separation distance of up to 2 km. The system shows substantial performance margins and a BER of less than 10 to the -10th. Descriptions are also given of techniques for rapid laser stabilization, clock recovery, and the detection of bursty data over a wide dynamic range. The dynamic time slot allocations (DTSA) access protocol, which makes efficient use of the data bus under heavy bus loading conditions, is defined.

Network Analysis Reveals the Recognition Mechanism for Mannose-binding Lectins

NASA Astrophysics Data System (ADS)

Zhao, Yunjie; Jian, Yiren; Zeng, Chen; Computational Biophysics Lab Team

The specific carbohydrate binding of mannose-binding lectin (MBL) protein in plants makes it a very useful molecular tool for cancer cell detection and other applications. The biological states of most MBL proteins are dimeric. Using dynamics network analysis on molecular dynamics (MD) simulations on the model protein of MBL, we elucidate the short- and long-range driving forces behind the dimer formation. The results are further supported by sequence coevolution analysis. We propose a general framework for deciphering the recognition mechanism underlying protein-protein interactions that may have potential applications in signaling pathways.

Parallel heterodyne detection of dynamic light-scattering spectra from gold nanoparticles diffusing in viscous fluids.

PubMed

Atlan, Michael; Desbiolles, Pierre; Gross, Michel; Coppey-Moisan, Maïté

2010-03-01

We developed a microscope intended to probe, using a parallel heterodyne receiver, the fluctuation spectrum of light quasi-elastically scattered by gold nanoparticles diffusing in viscous fluids. The cutoff frequencies of the recorded spectra scale up linearly with those expected from single-scattering formalism in a wide range of dynamic viscosities (1 to 15 times water viscosity at room temperature). Our scheme enables ensemble-averaged optical fluctuations measurements over multispeckle recordings in low light, at temporal frequencies up to 10 kHz, with a 12 Hz framerate array detector.

Parallel search for conjunctions with stimuli in apparent motion.

PubMed

Casco, C; Ganis, G

1999-01-01

A series of experiments was conducted to determine whether apparent motion tends to follow the similarity rule (i.e. is attribute-specific) and to investigate the underlying mechanism. Stimulus duration thresholds were measured during a two-alternative forced-choice task in which observers detected either the location or the motion direction of target groups defined by the conjunction of size and orientation. Target element positions were randomly chosen within a nominally defined rectangular subregion of the display (target region). The target region was presented either statically (followed by a 250 ms duration mask) or dynamically, displaced by a small distance (18 min of arc) from frame to frame. In the motion display, the position of both target and background elements was changed randomly from frame to frame within the respective areas to abolish spatial correspondence over time. Stimulus duration thresholds were lower in the motion than in the static task, indicating that target detection in the dynamic condition does not rely on the explicit identification of target elements in each static frame. Increasing the distractor-to-target ratio was found to reduce detectability in the static, but not in the motion task. This indicates that the perceptual segregation of the target is effortless and parallel with motion but not with static displays. The pattern of results holds regardless of the task or search paradigm employed. The detectability in the motion condition can be improved by increasing the number of frames and/or by reducing the width of the target area. Furthermore, parallel search in the dynamic condition can be conducted with both short-range and long-range motion stimuli. Finally, apparent motion of conjunctions is insufficient on its own to support location decision and is disrupted by random visual noise. Overall, these findings show that (i) the mechanism underlying apparent motion is attribute-specific; (ii) the motion system mediates temporal integration of feature conjunctions before they are identified by the static system; and (iii) target detectability in these stimuli relies upon a nonattentive, cooperative, directionally selective motion mechanism that responds to high-level attributes (conjunction of size and orientation).

Widely tunable telecom MEMS-VCSEL for terahertz photomixing.

PubMed

Haidar, Mohammad Tanvir; Preu, Sascha; Paul, Sujoy; Gierl, Christian; Cesar, Julijan; Emsia, Ali; Küppers, Franko

2015-10-01

We report frequency-tunable terahertz (THz) generation with a photomixer driven by an ultra-broadband tunable micro-electro-mechanical system vertical-cavity surface-emitting laser (MEMS-VCSEL) and a fixed-wavelength VCSEL, as well as a tunable MEMS-VCSEL mixed with a distributed feedback (DFB) diode. A total frequency span of 3.4 THz is covered in direct detection mode and 3.23 THz in the homodyne mode. The tuning range is solely limited by the dynamic range of the photomixers and the Schottky diode/photoconductor used in the experiment.

Bandwidth controller for phase-locked-loop

NASA Technical Reports Server (NTRS)

Brockman, Milton H. (Inventor)

1992-01-01

A phase locked loop utilizing digital techniques to control the closed loop bandwidth of the RF carrier phase locked loop in a receiver provides high sensitivity and a wide dynamic range for signal reception. After analog to digital conversion, a digital phase locked loop bandwidth controller provides phase error detection with automatic RF carrier closed loop tracking bandwidth control to accommodate several modes of transmission.

Vegetation monitoring to detect and predict vegetation change: Connecting historical and future shrub/steppe data in Yellowstone National Park

Treesearch

Geneva Chong; David Barnett; Benjamin Chemel; Roy Renkin; Pamela Sikkink

2011-01-01

A 2002 National Research Council (NRC) evaluation of ungulate management practices in Yellowstone specifically concluded that previous (1957 to present) vegetation monitoring efforts were insufficient to determine whether climate or ungulates were more influential on shrub/steppe dynamics on the northern ungulate winter range. The NRC further recommended that the...

Post-Fire Changes in Forest Biomass Retrieved by Airborne LiDAR in Amazonia

Treesearch

Luciane Sato; Vitor Gomes; Yosio Shimabukuro; Michael Keller; Egidio Arai; Maiza dos-Santos; Irving Brown; Luiz Aragão

2016-01-01

Fire is one of the main factors directly impacting Amazonian forest biomass and dynamics. Because of Amazonia’s large geographical extent, remote sensing techniques are required for comprehensively assessing forest fire impacts at the landscape level. In this context, Light Detection and Ranging (LiDAR) stands out as a technology capable of retrieving direct...

Quantitative performance characterization of three-dimensional noncontact fluorescence molecular tomography

NASA Astrophysics Data System (ADS)

Favicchio, Rosy; Psycharakis, Stylianos; Schönig, Kai; Bartsch, Dusan; Mamalaki, Clio; Papamatheakis, Joseph; Ripoll, Jorge; Zacharakis, Giannis

2016-02-01

Fluorescent proteins and dyes are routine tools for biological research to describe the behavior of genes, proteins, and cells, as well as more complex physiological dynamics such as vessel permeability and pharmacokinetics. The use of these probes in whole body in vivo imaging would allow extending the range and scope of current biomedical applications and would be of great interest. In order to comply with a wide variety of application demands, in vivo imaging platform requirements span from wide spectral coverage to precise quantification capabilities. Fluorescence molecular tomography (FMT) detects and reconstructs in three dimensions the distribution of a fluorophore in vivo. Noncontact FMT allows fast scanning of an excitation source and noninvasive measurement of emitted fluorescent light using a virtual array detector operating in free space. Here, a rigorous process is defined that fully characterizes the performance of a custom-built horizontal noncontact FMT setup. Dynamic range, sensitivity, and quantitative accuracy across the visible spectrum were evaluated using fluorophores with emissions between 520 and 660 nm. These results demonstrate that high-performance quantitative three-dimensional visible light FMT allowed the detection of challenging mesenteric lymph nodes in vivo and the comparison of spectrally distinct fluorescent reporters in cell culture.

Monitoring Single-Molecule Protein Dynamics with a Carbon Nanotube Transistor

NASA Astrophysics Data System (ADS)

Collins, Philip G.

2014-03-01

Nanoscale electronic devices like field-effect transistors have long promised to provide sensitive, label-free detection of biomolecules. Single-walled carbon nanotubes press this concept further by not just detecting molecules but also monitoring their dynamics in real time. Recent measurements have demonstrated this premise by monitoring the single-molecule processivity of three different enzymes: lysozyme, protein Kinase A, and the Klenow fragment of DNA polymerase I. With all three enzymes, single molecules tethered to nanotube transistors were electronically monitored for 10 or more minutes, allowing us to directly observe a range of activity including rare transitions to chemically inactive and hyperactive conformations. The high bandwidth of the nanotube transistors further allow every individual chemical event to be clearly resolved, providing excellent statistics from tens of thousands of turnovers by a single enzyme. Initial success with three different enzymes indicates the generality and attractiveness of the nanotube devices as a new tool to complement other single-molecule techniques. Research on transduction mechanisms provides the design rules necessary to further generalize this architecture and apply it to other proteins. The purposeful incorporation of just one amino acid is sufficient to fabricate effective, single molecule sensors from a wide range of enzymes or proteins.

The color of sea level: Importance of spatial variations in spectral shape for assessing the significance of trends

NASA Astrophysics Data System (ADS)

Hughes, Chris W.; Williams, Simon D. P.

2010-10-01

We investigate spatial variations in the shape of the spectrum of sea level variability based on a homogeneously sampled 12 year gridded altimeter data set. We present a method of plotting spectral information as color, focusing on periods between 2 and 24 weeks, which shows that significant spatial variations in the spectral shape exist and contain useful dynamical information. Using the Bayesian Information Criterion, we determine that, typically, a fifth-order autoregressive model is needed to capture the structure in the spectrum. Using this model, we show that statistical errors in fitted local trends range between less than 1 and more than 5 times of what would be calculated assuming "white" noise and that the time needed to detect a 1 mm/yr trend ranges between about 5 years and many decades. For global mean sea level, the statistical error reduces to 0.1 mm/yr over 12 years, with only 2 years needed to detect a 1 mm/yr trend. We find significant regional differences in trend from the global mean. The patterns of these regional differences are indicative of a sea level trend dominated by dynamical ocean processes over this period.

Micromachined ultrasonic transducers for air-coupled nondestructive evaluation

NASA Astrophysics Data System (ADS)

Hansen, Sean T.; Degertekin, F. Levent; Khuri-Yakub, Butrus T.

1999-01-01

Conventional methods of ultrasonic non-destructive evaluation (NDE) use liquids to couple sound waves into the test samples. This either requires immersion of the parts to be examined or the use of complex and bulky water squirting systems that must be scanned over the structure. Air-coupled ultrasonic systems eliminate these requirements if the losses at air-solid interfaces are tolerable. Micromachined capacitive ultrasonic transducers (cMUTs) have been shown to have more than 100 dB dynamic range when used in the bistatic transmission mode. In this paper, we present results of a pitch-catch transmission system using cMUTs that achieves a 103 dB dynamic range. Each transducer consists of 10,000 silicon nitride membranes of 100 micrometers diameter connected in parallel. This geometry result in transducers with a resonant frequency around 2.3 MHz. These transducers can be used in transmission experiments at normal incident to the sample or to excite and detect guided waves in aluminum and composite plates. In this paper we present ultrasonic defect detection results from both through transmission and guided Lamb wave experiments in aluminum and composite plates, such as those used in aircraft.

Ultra-low power high-dynamic range color pixel embedding RGB to r-g chromaticity transformation

NASA Astrophysics Data System (ADS)

Lecca, Michela; Gasparini, Leonardo; Gottardi, Massimo

2014-05-01

This work describes a novel color pixel topology that converts the three chromatic components from the standard RGB space into the normalized r-g chromaticity space. This conversion is implemented with high-dynamic range and with no dc power consumption, and the auto-exposure capability of the sensor ensures to capture a high quality chromatic signal, even in presence of very bright illuminants or in the darkness. The pixel is intended to become the basic building block of a CMOS color vision sensor, targeted to ultra-low power applications for mobile devices, such as human machine interfaces, gesture recognition, face detection. The experiments show that significant improvements of the proposed pixel with respect to standard cameras in terms of energy saving and accuracy on data acquisition. An application to skin color-based description is presented.

Importing super-resolution imaging into nanoscale puzzles of materials dynamics

NASA Astrophysics Data System (ADS)

King, John; Tsang, Chi Hang Boyce; Wilson, William; Granick, Steve

2014-03-01

A limitation of the exciting recent advances in sub-diffraction microscopy is that they focus on imaging rather than dynamical changes. We are engaged in extending this technique beyond the usual biological applications to address materials problems instead. To this end, we employ stimulated emission depletion (STED) microscopy, which relies on selectively turning off fluorescence emitters through stimulated emission, allowing only a small subset of emitters to be detected, such that the excitation spot size can be downsized to tens of nanometers. By coupling the STED excitation scheme to fluorescence correlation spectroscopy (FCS), diffusive processes are studied with nanoscale resolution. Here, we demonstrate the benefits of such experimental capabilities in a diverse range of complex systems, ranging from the diffusion of nano-objects in crowded 3D environments to the study of polymer diffusion on 2D surfaces.

Amorphous silicon balanced photodiode for microfluidic applications

NASA Astrophysics Data System (ADS)

Caputo, Domenico; de Cesare, Giampiero; Nascetti, Augusto; Scipinotti, Riccardo

2013-05-01

In this paper, we present the first integration of an amorphous silicon balanced photosensor with a microfluidic network to perform on-chip detection for biomedical applications, where rejection of large background light intensity is needed. This solution allows to achieve high resolution readout without the need of high dynamic range electronics. The balanced photodiode is constituted by two series-connected a-Si:H/a-SiC:H n-i-p stacked junctions, deposited on a glass substrate. The structure is a three terminal device where two electrodes bias the two diodes in reverse conditions while the third electrode (i.e. the connection point of the two diodes) provides the output signal given by the differential current. The microfluidic network is composed of two channels made in PolyDimetilSiloxane (PDMS) positioned over the glass substrate on the photodiode-side aligning each channel with a diode. This configuration guarantees an optimal optical coupling between luminescence events occurring in the channels and the photosensors. The experiments have been carried out measuring the differential current in identical and different conditions for the two channels. We have found that: the measurement dynamic range can be increased by at least an order of magnitude with respect to conventional photodiodes; the balanced photodiode is able to detect the presence or absence of water in the channel; the presence of fluorescent molecules in the channel can be successful detected by our device without any need of optical filter for the excitation light. These preliminary results demonstrate the successful integration of a microfluidic network with a-Si:H photosensor for on-chip detection in biomedical applications.

Polystyrene Oxygen Optodes Doped with Ir(III) and Pd(II) meso-Tetrakis(pentafluorophenyl)porphyrin Using an LED-Based High-Sensitivity Phosphorimeter.

PubMed

Filho, Alexandre F De Moraes; Gewehr, Pedro M; Maia, Joaquim M; Jakubiak, Douglas R

2018-06-15

This paper presents a gaseous oxygen detection system based on time-resolved phosphorimetry (time-domain), which is used to investigate O2 optical transducers. The primary sensing elements were formed by incorporating iridium(III) and palladium(II) meso -tetrakis(pentafluorophenyl)porphyrin complexes (IrTFPP-CO-Cl and PdTFPP) in polystyrene (PS) solid matrices. Probe excitation was obtained using a violet light-emitting diode (LED) (low power), and the resulting phosphorescence was detected by a high-sensitivity compact photomultiplier tube. The detection system performance and the preparation of the transducers are presented along with their optical properties, phosphorescence lifetimes, calibration curves and photostability. The developed lifetime measuring system showed a good signal-to-noise ratio, and reliable results were obtained from the optodes, even when exposed to moderate levels of O2. The new IrTFPP-CO-Cl membranes exhibited room temperature phosphorescence and moderate sensitivity: <τ0>/<τ21%> ratio of ≈6. A typically high degree of dynamic phosphorescence quenching was observed for the traditional indicator PdTFPP: <τ0>/<τ21%> ratio of ≈36. Pulsed-source time-resolved phosphorimetry combined with a high-sensitivity photodetector can offer potential advantages such as: (i) major dynamic range, (ii) extended temporal resolution (Δτ/Δ[O2]) and (iii) high operational stability. IrTFPP-CO-Cl immobilized in polystyrene is a promising alternative for O2 detection, offering adequate photostability and potentially mid-range sensitivity over Pt(II) and Pd(II) metalloporphyrins.

An interferometric fiber optic hydrophone with large upper limit of dynamic range

NASA Astrophysics Data System (ADS)

Zhang, Lei; Kan, Baoxi; Zheng, Baichao; Wang, Xuefeng; Zhang, Haiyan; Hao, Liangbin; Wang, Hailiang; Hou, Zhenxing; Yu, Wenpeng

2017-10-01

Interferometric fiber optic hydrophone based on heterodyne detection is used to measure the missile dropping point in the sea. The signal caused by the missile dropping in the water will be too large to be detected, so it is necessary to boost the upper limit of dynamic range (ULODR) of fiber optic hydrophone. In this article we analysis the factors which influence the ULODR of fiber optic hydrophone based on heterodyne detection, the ULODR is decided by the sampling frequency fsam and the heterodyne frequency Δf. The sampling frequency and the heterodyne frequency should be satisfied with the Nyquist sampling theorem which fsam will be two times larger than Δf, in this condition the ULODR is depended on the heterodyne frequency. In order to enlarge the ULODR, the Nyquist sampling theorem was broken, and we proposed a fiber optic hydrophone which the heterodyne frequency is larger than the sampling frequency. Both the simulation and experiment were done in this paper, the consequences are similar: When the sampling frequency is 100kHz, the ULODR of large heterodyne frequency fiber optic hydrophone is 2.6 times larger than that of the small heterodyne frequency fiber optic hydrophone. As the heterodyne frequency is larger than the sampling frequency, the ULODR is depended on the sampling frequency. If the sampling frequency was set at 2MHz, the ULODR of fiber optic hydrophone based on heterodyne detection will be boosted to 1000rad at 1kHz, and this large heterodyne fiber optic hydrophone can be applied to locate the drop position of the missile in the sea.

Automated assessment of blood flow in developing embryonic hearts by extending dynamic range of Doppler OCT using a MHz FDML swept laser source (Conference Presentation)

NASA Astrophysics Data System (ADS)

Elahi, Sahar; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

2017-02-01

Altered hemodynamics in developing embryonic hearts lead to congenital heart diseases, motivating close monitoring of blood flow over several stages of development. Doppler OCT can assess blood flow in tubular hearts, but the maximum velocity increases drastically during the period of cardiac cushion (valve precursors) formation. Therefore, the limited dynamic range of Doppler OCT velocity measurement makes it difficult to conduct longitudinal studies without phase wrapping at high velocities or loss of sensitivity to slow velocities. We have built a high-speed OCT system using an FDML laser (Optores GmbH, Germany) at a sweep rate of 1.68 MHz (axial resolution - 12 μm, sensitivity - 105 dB, phase stability - 17 mrad). The speed of this OCT system allows us to acquire high-density B-scans to obtain an extended velocity dynamic range without sacrificing the frame rate. The extended dynamic range within a frame is achieved by varying the A-scan interval at which the phase difference is found, enabling detection of velocities ranging from tens of microns per second to hundreds of mm per second. The extra lines in a frame can also be utilized to improve the structural and Doppler images via complex averaging. In structural images where presence of blood causes additional scattering, complex averaging helps retrieve features located deeper in the tissue. Moreover, high-density frames can be registered to 4D volumes to determine the orthogonal direction of flow and calculate shear stress. In conclusion, our high-speed OCT system will enable automated Doppler imaging of embryonic hearts in cohort studies.

Direct detection of fibrinogen in human plasma using electric-double-layer gated AlGaN/GaN high electron mobility transistors

NASA Astrophysics Data System (ADS)

Regmi, Abiral; Sarangadharan, Indu; Chen, Yen-Wen; Hsu, Chen-Pin; Lee, Geng-Yen; Chyi, Jen-Inn; Shiesh, Shu-Chu; Lee, Gwo-Bin; Wang, Yu-Lin

2017-08-01

Fibrinogen found in blood plasma is an important protein biomarker for potentially fatal diseases such as cardiovascular diseases. This study focuses on the development of an assay to detect plasmatic fibrinogen using electrical double layer gated AlGaN/GaN high electron mobility transistor biosensors without complex sample pre-treatment methods used in the traditional assays. The test results in buffer solution and clinical plasma samples show high sensitivity, specificity, and dynamic range. The sensor exhibits an ultra-low detection limit of 0.5 g/l and a detection range of 0.5-4.5 g/l in 1× PBS with 1% BSA. The concentration dependent sensor signal in human serum samples demonstrates the specificity to fibrinogen in a highly dense matrix of background proteins. The sensor does not require complicated automation, and quantitative results are obtained in 5 min with <5 μl sample volume. This sensing technique is ideal for speedy blood based diagnostics such as POC (point of care) tests, homecare tests, or personalized healthcare.

Photoinitiator Nucleotide for Quantifying Nucleic Acid Hybridization

PubMed Central

Johnson, Leah M.; Hansen, Ryan R.; Urban, Milan; Kuchta, Robert D.; Bowman, Christopher N.

2010-01-01

This first report of a photoinitiator-nucleotide conjugate demonstrates a novel approach for sensitive, rapid and visual detection of DNA hybridization events. This approach holds potential for various DNA labeling schemes and for applications benefiting from selective DNA-based polymerization initiators. Here, we demonstrate covalent, enzymatic incorporation of an eosin-photoinitiator 2′-deoxyuridine-5′-triphosphate (EITC-dUTP) conjugate into surface-immobilized DNA hybrids. Subsequent radical chain photoinitiation from these sites using an acrylamide/bis-acrylamide formulation yields a dynamic detection range between 500pM and 50nM of DNA target. Increasing EITC-nucleotide surface densities leads to an increase in surface-based polymer film heights until achieving a film height plateau of 280nm ±20nm at 610 ±70 EITC-nucleotides/μm2. Film heights of 10–20 nm were obtained from eosin surface densities of approximately 20 EITC-nucleotides/μm2 while below the detection limit of ~10 EITC-nucleotides/μm2, no detectable films were formed. This unique threshold behavior is utilized for instrument-free, visual quantification of target DNA concentration ranges. PMID:20337438

Improved porous silicon (P-Si) microarray based PSA (prostate specific antigen) immunoassay by optimized surface density of the capture antibody

PubMed Central

Lee, SangWook; Kim, Soyoun; Malm, Johan; Jeong, Ok Chan; Lilja, Hans; Laurell, Thomas

2014-01-01

Enriching the surface density of immobilized capture antibodies enhances the detection signal of antibody sandwich microarrays. In this study, we improved the detection sensitivity of our previously developed P-Si (porous silicon) antibody microarray by optimizing concentrations of the capturing antibody. We investigated immunoassays using a P-Si microarray at three different capture antibody (PSA - prostate specific antigen) concentrations, analyzing the influence of the antibody density on the assay detection sensitivity. The LOD (limit of detection) for PSA was 2.5ngmL−1, 80pgmL−1, and 800fgmL−1 when arraying the PSA antibody, H117 at the concentration 15µgmL−1, 35µgmL−1 and 154µgmL−1, respectively. We further investigated PSA spiked into human female serum in the range of 800fgmL−1 to 500ngmL−1. The microarray showed a LOD of 800fgmL−1 and a dynamic range of 800 fgmL−1 to 80ngmL−1 in serum spiked samples. PMID:24016590

Use of Mass Spectrometric Vapor Analysis To Improve Canine Explosive Detection Efficiency.

PubMed

Ong, Ta-Hsuan; Mendum, Ted; Geurtsen, Geoff; Kelley, Jude; Ostrinskaya, Alla; Kunz, Roderick

2017-06-20

Canines remain the gold standard for explosives detection in many situations, and there is an ongoing desire for them to perform at the highest level. This goal requires canine training to be approached similarly to scientific sensor design. Developing a canine training regimen is made challenging by a lack of understanding of the canine's odor environment, which is dynamic and typically contains multiple odorants. Existing methodology assumes that the handler's intention is an adequate surrogate for actual knowledge of the odors cuing the canine, but canines are easily exposed to unintentional explosive odors through training material cross-contamination. A sensitive, real-time (∼1 s) vapor analysis mass spectrometer was developed to provide tools, techniques, and knowledge to better understand, train, and utilize canines. The instrument has a detection library of nine explosives and explosive-related materials consisting of 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 2,4,6-trinitrotoluene (TNT), nitroglycerin (NG), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN), triacetone triperoxide (TATP), hexamethylene triperoxide diamine (HMTD), and cyclohexanone, with detection limits in the parts-per-trillion to parts-per-quadrillion range by volume. The instrument can illustrate aspects of vapor plume dynamics, such as detecting plume filaments at a distance. The instrument was deployed to support canine training in the field, detecting cross-contamination among training materials, and developing an evaluation method based on the odor environment. Support for training material production and handling was provided by studying the dynamic headspace of a nonexplosive HMTD training aid that is in development. These results supported existing canine training and identified certain areas that may be improved.

Ultrasensitive SERS Flow Detector Using Hydrodynamic Focusing

PubMed Central

Negri, Pierre; Jacobs, Kevin T.; Dada, Oluwatosin O.; Schultz, Zachary D.

2013-01-01

Label-free, chemical specific detection in flow is important for high throughput characterization of analytes in applications such as flow injection analysis, electrophoresis, and chromatography. We have developed a surface-enhanced Raman scattering (SERS) flow detector capable of ultrasensitive optical detection on the millisecond time scale. The device employs hydrodynamic focusing to improve SERS detection in a flow channel where a sheath flow confines analyte molecules eluted from a fused silica capillary over a planar SERS-active substrate. Increased analyte interactions with the SERS substrate significantly improve detection sensitivity. The performance of this flow detector was investigated using a combination of finite element simulations, fluorescence imaging, and Raman experiments. Computational fluid dynamics based on finite element analysis was used to optimize the flow conditions. The modeling indicates that a number of factors, such as the capillary dimensions and the ratio of the sheath flow to analyte flow rates, are critical for obtaining optimal results. Sample confinement resulting from the flow dynamics was confirmed using wide-field fluorescence imaging of rhodamine 6G (R6G). Raman experiments at different sheath flow rates showed increased sensitivity compared with the modeling predictions, suggesting increased adsorption. Using a 50-millisecond acquisitions, a sheath flow rate of 180 μL/min, and a sample flow rate of 5 μL/min, a linear dynamic range from nanomolar to micromolar concentrations of R6G with a LOD of 1 nM is observed. At low analyte concentrations, rapid analyte desorption is observed, enabling repeated and high-throughput SERS detection. The flow detector offers substantial advantages over conventional SERS-based assays such as minimal sample volumes and high detection efficiency. PMID:24074461

Past and future detector arrays for complete event reconstruction in heavy-ion reactions

NASA Astrophysics Data System (ADS)

Cardella, G.; Acosta, L.; Auditore, L.; Boiano, C.; Castoldi, A.; D'Andrea, M.; De Filippo, E.; Dell'Aquila, D.; De Luca, S.; Fichera, F.; Giudice, N.; Gnoffo, B.; Grimaldi, A.; Guazzoni, C.; Lanzalone, G.; Librizzi, F.; Lombardo, I.; Maiolino, C.; Maffesanti, S.; Martorana, N. S.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Parsani, T.; Passaro, G.; Pirrone, S.; Politi, G.; Previdi, F.; Quattrocchi, L.; Rizzo, F.; Russotto, P.; Saccà, G.; Salemi, G.; Sciliberto, D.; Trifirò, A.; Trimarchi, M.; Vigilante, M.

2017-11-01

Complex and more and more complete detector arrays have been developed in the last two decades, or are in advanced design stage, in different laboratories. Such arrays are necessary to fully characterize nuclear reactions induced by stable and exotic beams. The need for contemporary detection of charged particles, and/or γ -rays, and/or neutrons, has been stressed in many fields of nuclear structure and reaction dynamics, with particular attention to the improvement of both high angular and energy resolution. Some examples of detection systems adapted to various energy ranges is discussed. Emphasis is given to the possible update of relatively old 4π detectors with new electronics and new detection methods.

A Multiscale Vision Model applied to analyze EIT images of the solar corona

NASA Astrophysics Data System (ADS)

Portier-Fozzani, F.; Vandame, B.; Bijaoui, A.; Maucherat, A. J.; EIT Team

2001-07-01

The large dynamic range provided by the SOHO/EIT CCD (1 : 5000) is needed to observe the large EUV zoom of coronal structures from coronal homes up to flares. Histograms show that often a wide dynamic range is present in each image. Extracting hidden structures in the background level requires specific techniques such as the use of the Multiscale Vision Model (MVM, Bijaoui et al., 1998). This method, based on wavelet transformations optimizes detection of various size objects, however complex they may be. Bijaoui et al. built the Multiscale Vision Model to extract small dynamical structures from noise, mainly for studying galaxies. In this paper, we describe requirements for the use of this method with SOHO/EIT images (calibration, size of the image, dynamics of the subimage, etc.). Two different areas were studied revealing hidden structures: (1) classical coronal mass ejection (CME) formation and (2) a complex group of active regions with its evolution. The aim of this paper is to define carefully the constraints for this new method of imaging the solar corona with SOHO/EIT. Physical analysis derived from multi-wavelength observations will later complete these first results.

Detection of microparticles in dynamic processes

NASA Astrophysics Data System (ADS)

Ten, K. A.; Pruuel, E. R.; Kashkarov, A. O.; Rubtsov, I. A.; Shechtman, L. I.; Zhulanov, V. V.; Tolochko, B. P.; Rykovanov, G. N.; Muzyrya, A. K.; Smirnov, E. B.; Stolbikov, M. Yu; Prosvirnin, K. M.

2016-11-01

When a metal plate is subjected to a strong shock impact, its free surface emits a flow of particles of different sizes (shock-wave “dusting”). Traditionally, the process of dusting is investigated by the methods of pulsed x-ray or piezoelectric sensor or via an optical technique. The particle size ranges from a few microns to hundreds of microns. The flow is assumed to include also finer particles, which cannot be detected with the existing methods yet. On the accelerator complex VEPP-3-VEPP-4 at the BINP there are two experiment stations for research on fast processes, including explosion ones. The stations enable measurement of both passed radiation (absorption) and small-angle x-ray scattering on synchrotron radiation (SR). Radiation is detected with a precision high-speed detector DIMEX. The detector has an internal memory of 32 frames, which enables recording of the dynamics of the process (shooting of movies) with intervals of 250 ns to 2 μs. Flows of nano- and microparticles from free surfaces of various materials (copper and tin) have been examined. Microparticle flows were emitted from grooves of 50-200 μs in size and joints (gaps) between metal parts. With the soft x-ray spectrum of SR one can explore the dynamics of a single microjet of micron size. The dynamics of density distribution along micro jets were determined. Under a shock wave (∼ 60 GPa) acting on tin disks, flows of microparticles from a smooth surface were recorded.

A unique charge-coupled device/xenon arc lamp based imaging system for the accurate detection and quantitation of multicolour fluorescence.

PubMed

Spibey, C A; Jackson, P; Herick, K

2001-03-01

In recent years the use of fluorescent dyes in biological applications has dramatically increased. The continual improvement in the capabilities of these fluorescent dyes demands increasingly sensitive detection systems that provide accurate quantitation over a wide linear dynamic range. In the field of proteomics, the detection, quantitation and identification of very low abundance proteins are of extreme importance in understanding cellular processes. Therefore, the instrumentation used to acquire an image of such samples, for spot picking and identification by mass spectrometry, must be sensitive enough to be able, not only, to maximise the sensitivity and dynamic range of the staining dyes but, as importantly, adapt to the ever changing portfolio of fluorescent dyes as they become available. Just as the available fluorescent probes are improving and evolving so are the users application requirements. Therefore, the instrumentation chosen must be flexible to address and adapt to those changing needs. As a result, a highly competitive market for the supply and production of such dyes and the instrumentation for their detection and quantitation have emerged. The instrumentation currently available is based on either laser/photomultiplier tube (PMT) scanning or lamp/charge-coupled device (CCD) based mechanisms. This review briefly discusses the advantages and disadvantages of both System types for fluorescence imaging, gives a technical overview of CCD technology and describes in detail a unique xenon/are lamp CCD based instrument, from PerkinElmer Life Sciences. The Wallac-1442 ARTHUR is unique in its ability to scan both large areas at high resolution and give accurate selectable excitation over the whole of the UV/visible range. It operates by filtering both the excitation and emission wavelengths, providing optimal and accurate measurement and quantitation of virtually any available dye and allows excellent spectral resolution between different fluorophores. This flexibility and excitation accuracy is key to multicolour applications and future adaptation of the instrument to address the application requirements and newly emerging dyes.

Research on measurement method of optical camouflage effect of moving object

NASA Astrophysics Data System (ADS)

Wang, Juntang; Xu, Weidong; Qu, Yang; Cui, Guangzhen

2016-10-01

Camouflage effectiveness measurement as an important part of the camouflage technology, which testing and measuring the camouflage effect of the target and the performance of the camouflage equipment according to the tactical and technical requirements. The camouflage effectiveness measurement of current optical band is mainly aimed at the static target which could not objectively reflect the dynamic camouflage effect of the moving target. This paper synthetical used technology of dynamic object detection and camouflage effect detection, the digital camouflage of the moving object as the research object, the adaptive background update algorithm of Surendra was improved, a method of optical camouflage effect detection using Lab-color space in the detection of moving-object was presented. The binary image of moving object is extracted by this measurement technology, in the sequence diagram, the characteristic parameters such as the degree of dispersion, eccentricity, complexity and moment invariants are constructed to construct the feature vector space. The Euclidean distance of moving target which through digital camouflage was calculated, the results show that the average Euclidean distance of 375 frames was 189.45, which indicated that the degree of dispersion, eccentricity, complexity and moment invariants of the digital camouflage graphics has a great difference with the moving target which not spray digital camouflage. The measurement results showed that the camouflage effect was good. Meanwhile with the performance evaluation module, the correlation coefficient of the dynamic target image range 0.1275 from 0.0035, and presented some ups and down. Under the dynamic condition, the adaptability of target and background was reflected. In view of the existing infrared camouflage technology, the next step, we want to carry out the camouflage effect measurement technology of the moving target based on infrared band.

Direct electron transfer of glucose oxidase-boron doped diamond interface: a new solution for a classical problem.

PubMed

Bai, Yan-Feng; Xu, Tai-Bin; Luong, John H T; Cui, Hui-Fang

2014-05-20

A planar boron-doped diamond (BDD) electrode was treated with KOH and functionalized with 3-aminopropyltriethoxysilane (APTES) to serve as a biosensing platform for biomolecule immobilization with glucose oxidase (GOx) as a test model. The free amino groups of GOx and APTES were cross-linked by glutaraldehyde (X), a bifunctional chemical to form a stable enzyme layer (GOx-X-APTES) on BDD. Micrographs obtained by scanning electron microscopy revealed that a mesoporous structure uniformly covered the BDD surface. Cyclic voltammetry of GOx immobilized showed a pair of well-defined redox peaks in neutral phosphate buffer solution, corresponding to the direct electron transfer of GOx. The apparent heterogeneous electron transfer rate constant of the immobilized GOx was estimated to be 8.85 ± 0.47 s(-1), considerably higher than the literature reported values. The determination of glucose was carried out by amperometry at -0.40 V, and the developed biosensor showed good reproducibility and stability with a detection limit of 20 μM. Both ascorbic and uric acids at normal physiological conditions did not provoke any signals. The dynamic range of glucose detection was further extended by covering the enzyme electrode with a thin Nafion layer. The Nafion/GOx-X-APTES/BDD biosensor showed excellent stability, a detection limit of 30 μM, a linear range between 35 μM and 8 mM, and a dynamic range up to 14 mM. Such analytical performances were compared favorably with other complicated sensing schemes using nanomaterials, redox polymers, and nanowires. The APTES-functionalized BDD could be easily extended to immobilize other redox enzymes or proteins of interests.

A Disposable Tear Glucose Biosensor—Part 2: System Integration and Model Validation

PubMed Central

La Belle, Jeffrey T.; Bishop, Daniel K.; Vossler, Stephen R.; Patel, Dharmendra R.; Cook, Curtiss B.

2010-01-01

Background We presented a concept for a tear glucose sensor system in an article by Bishop and colleagues in this issue of Journal of Diabetes Science and Technology. A unique solution to collect tear fluid and measure glucose was developed. Individual components were selected, tested, and optimized, and system error modeling was performed. Further data on prototype testing are now provided. Methods An integrated fluidics portion of the prototype was designed, cast, and tested. A sensor was created using screen-printed sensors integrated with a silicone rubber fluidics system and absorbent polyurethane foam. A simulated eye surface was prepared using fluid-saturated poly(2-hydroxyethyl methacrylate) sheets, and the disposable prototype was tested for both reproducibility at 0, 200, and 400 μM glucose (n = 7) and dynamic range of glucose detection from 0 to 1000 μM glucose. Results From the replicated runs, an established relative standard deviation of 15.8% was calculated at 200 μM and a lower limit of detection was calculated at 43.4 μM. A linear dynamic range was demonstrated from 0 to 1000 μM with an R2 of 99.56%. The previously developed model predicted a 14.9% variation. This compares to the observed variance of 15.8% measured at 200 μM glucose. Conclusion With the newly designed fluidics component, an integrated tear glucose prototype was assembled and tested. Testing of this integrated prototype demonstrated a satisfactory lower limit of detection for measuring glucose concentration in tears and was reproducible across a physiological sampling range. The next step in the device design process will be initial animal studies to evaluate the current prototype for factors such as eye irritation, ease of use, and correlation with blood glucose. PMID:20307390

A disposable tear glucose biosensor-part 2: system integration and model validation.

PubMed

La Belle, Jeffrey T; Bishop, Daniel K; Vossler, Stephen R; Patel, Dharmendra R; Cook, Curtiss B

2010-03-01

We presented a concept for a tear glucose sensor system in an article by Bishop and colleagues in this issue of Journal of Diabetes Science and Technology. A unique solution to collect tear fluid and measure glucose was developed. Individual components were selected, tested, and optimized, and system error modeling was performed. Further data on prototype testing are now provided. An integrated fluidics portion of the prototype was designed, cast, and tested. A sensor was created using screen-printed sensors integrated with a silicone rubber fluidics system and absorbent polyurethane foam. A simulated eye surface was prepared using fluid-saturated poly(2-hydroxyethyl methacrylate) sheets, and the disposable prototype was tested for both reproducibility at 0, 200, and 400 microM glucose (n = 7) and dynamic range of glucose detection from 0 to 1000 microM glucose. From the replicated runs, an established relative standard deviation of 15.8% was calculated at 200 microM and a lower limit of detection was calculated at 43.4 microM. A linear dynamic range was demonstrated from 0 to 1000 microM with an R(2) of 99.56%. The previously developed model predicted a 14.9% variation. This compares to the observed variance of 15.8% measured at 200 microM glucose. With the newly designed fluidics component, an integrated tear glucose prototype was assembled and tested. Testing of this integrated prototype demonstrated a satisfactory lower limit of detection for measuring glucose concentration in tears and was reproducible across a physiological sampling range. The next step in the device design process will be initial animal studies to evaluate the current prototype for factors such as eye irritation, ease of use, and correlation with blood glucose. (c) 2010 Diabetes Technology Society.

Advances in Multicollector ICPMS for precise and accurate isotope ratio measurements of Uranium isotopes

NASA Astrophysics Data System (ADS)

Bouman, C.; Lloyd, N. S.; Schwieters, J.

2011-12-01

The accurate and precise determination of uranium isotopes is challenging, because of the large dynamic range posed by the U isotope abundances and the limited available sample material. Various mass spectrometric techniques are used for the measurement of U isotopes, where TIMS is the most accepted and accurate one. Multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) can offer higher productivity compared to TIMS, but is traditionally limited by low efficiency of sample utilisation. This contribution will discuss progress in MC-ICPMS for detecting 234U, 235U, 236U and 238U in various uranium reference materials from IRMM and NBL. The Thermo Scientific NEPTUNE Plus with Jet Interface offers a modified dry plasma ICP interface using a large interface pump combined with a special set of sample and skimmer cones giving ultimate sensitivity for all elements across the mass range. For uranium, an ion yield of > 3 % was reported previously [1]. The NEPTUNE Plus also offers Multi Ion Counting using discrete dynode electron multipliers as well as two high abundance-sensitivity filters to discriminate against peak tailing effects on 234U and 236U originating from the major uranium beams. These improvements in sensitivity and dynamic range allow accurate measurements of 234U, 235U and 236U abundances on very small samples and at low concentration. In our approach, minor U isotopes 234U and 236U were detected on ion counters with high abundance sensitivity filters, whereas 235U and 238U were detected on Faraday Cups using a high gain current amplifier (10e12 Ohm) for 235U. Precisions and accuracies for 234U and 236U were down to ~1%. For 235U, subpermil levels were reached.

Dynamic light scattering for the characterization and counting of extracellular vesicles: a powerful noninvasive tool

NASA Astrophysics Data System (ADS)

Palmieri, Valentina; Lucchetti, Donatella; Gatto, Ilaria; Maiorana, Alessandro; Marcantoni, Margherita; Maulucci, Giuseppe; Papi, Massimiliano; Pola, Roberto; De Spirito, Marco; Sgambato, Alessandro

2014-09-01

Extracellular vesicles (EVs) are cell-to-cell shuttles that have recently drawn interest both as drug delivery platforms and disease biomarkers. Despite the increasingly recognized relevance of these vesicles, their detection, and characterization still have several technical drawbacks. In this paper, we accurately assess the size distribution and concentration of EVs by using a high-throughput non-perturbative technique such as Dynamic Light Scattering (DLS). The vesicle radii distribution, as further confirmed by Atomic Force Microscopy experiments, ranges from 10 to 80 nm and appears very asymmetric towards larger radii with a main peak at roughly 30 nm. By combining DLS and Bradford assay, we also demonstrate the feasibility of recovering the concentration and its distribution of proteins contained inside vesicles. The sensitivity of our approach allows to detect protein concentrations as low as 0.01 mg/ml.

Efficient, Decentralized Detection of Qualitative Spatial Events in a Dynamic Scalar Field

PubMed Central

Jeong, Myeong-Hun; Duckham, Matt

2015-01-01

This paper describes an efficient, decentralized algorithm to monitor qualitative spatial events in a dynamic scalar field. The events of interest involve changes to the critical points (i.e., peak, pits and passes) and edges of the surface network derived from the field. Four fundamental types of event (appearance, disappearance, movement and switch) are defined. Our algorithm is designed to rely purely on qualitative information about the neighborhoods of nodes in the sensor network and does not require information about nodes’ coordinate positions. Experimental investigations confirm that our algorithm is efficient, with O(n) overall communication complexity (where n is the number of nodes in the sensor network), an even load balance and low operational latency. The accuracy of event detection is comparable to established centralized algorithms for the identification of critical points of a surface network. Our algorithm is relevant to a broad range of environmental monitoring applications of sensor networks. PMID:26343672

Adaptation without parameter change: Dynamic gain control in motion detection

PubMed Central

Borst, Alexander; Flanagin, Virginia L.; Sompolinsky, Haim

2005-01-01

Many sensory systems adapt their input-output relationship to changes in the statistics of the ambient stimulus. Such adaptive behavior has been measured in a motion detection sensitive neuron of the fly visual system, H1. The rapid adaptation of the velocity response gain has been interpreted as evidence of optimal matching of the H1 response to the dynamic range of the stimulus, thereby maximizing its information transmission. Here, we show that correlation-type motion detectors, which are commonly thought to underlie fly motion vision, intrinsically possess adaptive properties. Increasing the amplitude of the velocity fluctuations leads to a decrease of the effective gain and the time constant of the velocity response without any change in the parameters of these detectors. The seemingly complex property of this adaptation turns out to be a straightforward consequence of the multidimensionality of the stimulus and the nonlinear nature of the system. PMID:15833815

Imaging electric field dynamics with graphene optoelectronics.

PubMed

Horng, Jason; Balch, Halleh B; McGuire, Allister F; Tsai, Hsin-Zon; Forrester, Patrick R; Crommie, Michael F; Cui, Bianxiao; Wang, Feng

2016-12-16

The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts, a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena.

Efficient, Decentralized Detection of Qualitative Spatial Events in a Dynamic Scalar Field.

PubMed

Jeong, Myeong-Hun; Duckham, Matt

2015-08-28

This paper describes an efficient, decentralized algorithm to monitor qualitative spatial events in a dynamic scalar field. The events of interest involve changes to the critical points (i.e., peak, pits and passes) and edges of the surface network derived from the field. Four fundamental types of event (appearance, disappearance, movement and switch) are defined. Our algorithm is designed to rely purely on qualitative information about the neighborhoods of nodes in the sensor network and does not require information about nodes' coordinate positions. Experimental investigations confirm that our algorithm is efficient, with O(n) overall communication complexity (where n is the number of nodes in the sensor network), an even load balance and low operational latency. The accuracy of event detection is comparable to established centralized algorithms for the identification of critical points of a surface network. Our algorithm is relevant to a broad range of environmental monitoring applications of sensor networks.

FLOWS AND WAVES IN BRAIDED SOLAR CORONAL MAGNETIC STRUCTURES

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

Pant, V.; Datta, A.; Banerjee, D., E-mail: vaibhav@iiap.res.in

We study the high frequency dynamics in the braided magnetic structure of an active region (AR 11520) moss as observed by the High-Resolution Coronal Imager (Hi-C). We detect quasi-periodic flows and waves in these structures. We search for high frequency dynamics while looking at power maps of the observed region. We find that shorter periodicities (30–60 s) are associated with small spatial scales which can be resolved by Hi-C only. We detect quasi-periodic flows with a wide range of velocities, from 13–185 km s{sup −1}, associated with braided regions. This can be interpreted as plasma outflows from reconnection sites. Wemore » also find short period and large amplitude transverse oscillations associated with the braided magnetic region. Such oscillations could be triggered by reconnection or such oscillations may trigger reconnection.« less

Phase Coexistence in a Dynamic Phase Diagram.

PubMed

Gentile, Luigi; Coppola, Luigi; Balog, Sandor; Mortensen, Kell; Ranieri, Giuseppe A; Olsson, Ulf

2015-08-03

Metastability and phase coexistence are important concepts in colloidal science. Typically, the phase diagram of colloidal systems is considered at the equilibrium without the presence of an external field. However, several studies have reported phase transition under mechanical deformation. The reason behind phase coexistence under shear flow is not fully understood. Here, multilamellar vesicle (MLV)-to-sponge (L3 ) and MLV-to-Lα transitions upon increasing temperature are detected using flow small-angle neutron scattering techniques. Coexistence of Lα and MLV phases at 40 °C under shear flow is detected by using flow NMR spectroscopy. The unusual rheological behavior observed by studying the lamellar phase of a non-ionic surfactant is explained using (2) H NMR and diffusion flow NMR spectroscopy with the coexistence of planar lamellar-multilamellar vesicles. Moreover, a dynamic phase diagram over a wide range of temperatures is proposed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Changing roles of propagule, climate, and land use during extralimital colonization of a rose chafer beetle

NASA Astrophysics Data System (ADS)

Horak, Jakub; Hui, Cang; Roura-Pascual, Núria; Romportl, Dusan

2013-04-01

Regardless of their ecosystem functions, some insects are threatened when facing environmental changes and disturbances, while others become extremely successful. It is crucial for successful conservation to differentiate factors supporting species' current distributions from those triggering range dynamics. Here, we studied the sudden extralimital colonization of the rose chafer beetle, Oxythyrea funesta, in the Czech Republic. Specifically, we depicted the range expansion using accumulated historical records of first known occurrences and then explained the colonization events using five transformed indices depicting changes in local propagule pressure (LPP), climate, land use, elevation, and landscape structure. The slow occupancy increase of O. funesta before 1990 changed to a phase of rapid occupancy increase after 1990, driven not only by changes in the environment (climate and land use) but also by the spatial accumulation of LPP. Climate was also found to play a significant role but only during the niche-filling stage before 1990, while land use became important during the phase of rapid expansion after 1990. Inland waters (e.g., riparian corridors) also contributed substantially to the spread in the Czech Republic. Our method of using spatially transformed variables to explain the colonization events provides a novel way of detecting factors triggering range dynamics. The results highlight the importance of LPP in driving sudden occupancy increase of extralimital species and recommend the use of LPP as an important predictor for modeling range dynamics.

Imprinted Oxide and MIP/Oxide Hybrid Nanomaterials for Chemical Sensors †

PubMed Central

2018-01-01

The oxides of transition, post-transition and rare-earth metals have a long history of robust and fast responsive recognition elements for electronic, optical, and gravimetric devices. A wide range of applications successfully utilized pristine or doped metal oxides and polymer-oxide hybrids as nanostructured recognition elements for the detection of biologically relevant molecules, harmful organic substances, and drugs as well as for the investigative process control applications. An overview of the selected recognition applications of molecularly imprinted sol-gel phases, metal oxides and hybrid nanomaterials composed of molecularly imprinted polymers (MIP) and metal oxides is presented herein. The formation and fabrication processes for imprinted sol-gel layers, metal oxides, MIP-coated oxide nanoparticles and other MIP/oxide nanohybrids are discussed along with their applications in monitoring bioorganic analytes and processes. The sensor characteristics such as dynamic detection range and limit of detection are compared as the performance criterion and the miniaturization and commercialization possibilities are critically discussed. PMID:29677107

Quantitative electrochemical metalloimmunoassay for TFF3 in urine using a paper analytical device.

PubMed

DeGregory, Paul R; Tsai, Yi-Ju; Scida, Karen; Richards, Ian; Crooks, Richard M

2016-03-07

We report a paper-based assay platform for the detection of the kidney disease marker Trefoil Factor 3 (TFF3) in human urine. The sensor is based on a quantitative metalloimmunoassay that can determine TFF3 concentrations via electrochemical detection of environmentally stable silver nanoparticle (AgNP) labels attached to magnetic microbeads via a TFF3 immunosandwich. The paper electroanalytical device incorporates two preconcentration steps that make it possible to detect concentrations of TFF3 in human urine at the low end of the target TFF3 concentration range (0.03-7.0 μg mL(-1)). Importantly, the paper device provides a level of accuracy for TFF3 determination in human urine equivalent to that of a commercial kit. The paper sensor has a dynamic range of ∼2.5 orders of magnitude, only requires a simple, one-step incubation protocol, and is fast, requiring only 10 min to complete. The cost of the materials at the prototypic laboratory scale, excluding reagents, is just US$0.42.

Imprinted Oxide and MIP/Oxide Hybrid Nanomaterials for Chemical Sensors †.

PubMed

Afzal, Adeel; Dickert, Franz L

2018-04-20

The oxides of transition, post-transition and rare-earth metals have a long history of robust and fast responsive recognition elements for electronic, optical, and gravimetric devices. A wide range of applications successfully utilized pristine or doped metal oxides and polymer-oxide hybrids as nanostructured recognition elements for the detection of biologically relevant molecules, harmful organic substances, and drugs as well as for the investigative process control applications. An overview of the selected recognition applications of molecularly imprinted sol-gel phases, metal oxides and hybrid nanomaterials composed of molecularly imprinted polymers (MIP) and metal oxides is presented herein. The formation and fabrication processes for imprinted sol-gel layers, metal oxides, MIP-coated oxide nanoparticles and other MIP/oxide nanohybrids are discussed along with their applications in monitoring bioorganic analytes and processes. The sensor characteristics such as dynamic detection range and limit of detection are compared as the performance criterion and the miniaturization and commercialization possibilities are critically discussed.

Design and analysis of APD photoelectric detecting circuit

NASA Astrophysics Data System (ADS)

Fang, R.; Wang, C.

2015-11-01

In LADAR system, photoelectric detecting circuit is the key part in photoelectric conversion, which determines speed of respond, sensitivity and fidelity of the system. This paper presents the design of a matched APD Photoelectric detecting circuit. The circuit accomplishes low-noise readout and high-gain amplification of the weak photoelectric signal. The main performances, especially noise and transient response of the circuit are analyzed. In order to obtain large bandwidth, decompensated operational amplifiers are applied. Circuit simulations allow the architecture validation and the global performances to be predicted. The simulation results show that the gain of the detecting circuit is 630kΩ while the bandwidth is 100MHz, and 28dB dynamic range is achieved. Furthermore, the variation of the output pulse width is less than 0.9ns.

Design and field application of a UV-LED based optical fiber biofilm sensor.

PubMed

Fischer, Matthias; Wahl, Martin; Friedrichs, Gernot

2012-03-15

Detecting changes in the formation dynamics of biofilms stemming from bacteria and unicellular microorganisms in their natural environment is of prime interest for biological, ecological as well as anti-fouling technology research. We developed a robust optical fiber-based biofilm sensor ready to be applied in natural aquatic environments for on-line, in situ and non-destructive monitoring of large-area biofilms. The device is based on the detection of the natural fluorescence of microorganisms constituting the biofilm. Basically, the intrinsic fluorescence of the amino acid tryptophan is excited at a wavelength of λ=280 nm and detected at λ=350 nm utilising a numerically optimized sensor head equipped with a UV-LED light source and optical fiber bundles for efficient fluorescence light collection. Calibration was carried out with tryptophan solutions and two characteristic marine bacteria strains revealing linear signal response, satisfactory background suppression, wide dynamic range, and an experimental detection limit of 4 × 10(3)cells/cm(2). Successful field experiments in the Baltic Sea accomplished over a period of twenty-one days provided for the first time continuous observation of biofilm formation dynamics in a natural habitat. Starting from the first adhering bacteria, the measurement yielded the characteristic three phases of biofilm formation up to a fully developed biofilm. The sensor system holds potential for applications in aquatic sciences including deep sea research and, after further miniaturisation, in the industrial and biomedical field. Copyright © 2012 Elsevier B.V. All rights reserved.

12.2-GHz methanol maser MMB follow-up catalogue - IV. Longitude range 20°-60°

NASA Astrophysics Data System (ADS)

Breen, S. L.; Ellingsen, S. P.; Caswell, J. L.; Green, J. A.; Voronkov, M. A.; Avison, A.; Fuller, G. A.; Quinn, L. J.

2016-07-01

This is the fourth and final instalment of a series of catalogues presenting 12.2-GHz methanol maser observations made towards each of the 6.7-GHz methanol masers detected in the Methanol Multibeam (MMB) survey. This final portion of the survey covers the 20°-60° longitude range, increasing the 12.2-GHz follow-up range to the full MMB coverage of 186° ≥ l ≤ 60° and |b| ≤ 2°. Towards a total of 260 6.7-GHz MMB methanol masers (we were unable to observe five of the MMB sources in this longitude range) we detect 116 12.2-GHz masers counterparts, 64 of which were discovered in this survey. Including data from the literature, we find that there are 12.2-GHz methanol masers towards 47.1 per cent of the 6.7-GHz methanol masers in this portion of the Galaxy. Across the entire MMB survey range, we find a detection rate of 45.3 per cent. We find that the detection rate of 12.2-GHz methanol masers as a function of Galactic longitude is not uniform and there is an excess of masers with broad velocity ranges at longitudes near 30° and 330°. Comparing the occurrence of 12.2-GHz methanol masers with MMB-targeted CO observations has shown that those outflows associated with a 12.2-GHz source have a larger average dynamical time-scale than those associated with only 6.7-GHz methanol masers, supporting the notion that the 12.2-GHz masers are associated with a later phase of high-mass star formation.

A simplified guide for charged aerosol detection of non-chromophoric compounds-Analytical method development and validation for the HPLC assay of aerosol particle size distribution for amikacin.

PubMed

Soliven, Arianne; Haidar Ahmad, Imad A; Tam, James; Kadrichu, Nani; Challoner, Pete; Markovich, Robert; Blasko, Andrei

2017-09-05

Amikacin, an aminoglycoside antibiotic lacking a UV chromophore, was developed into a drug product for delivery by inhalation. A robust method for amikacin assay analysis and aerosol particle size distribution (aPSD) determination, with comparable performance to the conventional UV detector was developed using a charged aerosol detector (CAD). The CAD approach involved more parameters for optimization than UV detection due to its sensitivity to trace impurities, non-linear response and narrow dynamic range of signal versus concentration. Through careful selection of the power transformation function value and evaporation temperature, a wider linear dynamic range, improved signal-to-noise ratio and high repeatability were obtained. The influences of mobile phase grade and glassware binding of amikacin during sample preparation were addressed. A weighed (1/X 2 ) least square regression was used for the calibration curve. The limit of quantitation (LOQ) and limit of detection (LOD) for this method were determined to be 5μg/mL and 2μg/mL, respectively. The method was validated over a concentration range of 0.05-2mg/mL. The correlation coefficient for the peak area versus concentration was 1.00 and the y-intercept was 0.2%. The recovery accuracies of triplicate preparations at 0.05, 1.0, and 2.0mg/mL were in the range of 100-101%. The relative standard deviation (S rel ) of six replicates at 1.0mg/mL was 1%, and S rel of five injections at the limit of quantitation was 4%. A robust HPLC-CAD method was developed and validated for the determination of the aPSD for amikacin. The CAD method development produced a simplified procedure with minimal variability in results during: routine operation, transfer from one instrument to another, and between different analysts. Copyright © 2017 Elsevier B.V. All rights reserved.

Wide-dynamic-range forward suppression in marmoset inferior colliculus neurons is generated centrally and accounts for perceptual masking.

PubMed

Nelson, Paul C; Smith, Zachary M; Young, Eric D

2009-02-25

An organism's ability to detect and discriminate sensory inputs depends on the recent stimulus history. For example, perceptual detection thresholds for a brief tone can be elevated by as much as 50 dB when following a masking stimulus. Previous work suggests that such forward masking is not a direct result of peripheral neural adaptation; the central pathway apparently modifies the representation in a way that further attenuates the input's response to short probe signals. Here, we show that much of this transformation is complete by the level of the inferior colliculus (IC). Single-neuron extracellular responses were recorded in the central nucleus of the awake marmoset IC. The threshold for a 20 ms probe tone presented at best frequency was determined for various masker-probe delays, over a range of masker sound pressure levels (SPLs) and frequencies. The most striking aspect of the data was the increased potency of forward maskers as their SPL was increased, despite the fact that the excitatory response to the masker was often saturating or nonmonotonic over the same range of levels. This led to probe thresholds at high masker levels that were almost always higher than those observed in the auditory nerve. Probe threshold shifts were not usually caused by a persistent excitatory response to the masker; instead we propose a wide-dynamic-range inhibitory mechanism locked to sound offset as an explanation for several key aspects of the data. These findings further delineate the role of subcortical auditory processing in the generation of a context-dependent representation of ongoing acoustic scenes.

Wide dynamic range forward suppression in marmoset inferior colliculus neurons is generated centrally and accounts for perceptual masking

PubMed Central

Nelson, Paul C.; Smith, Zachary M.; Young, Eric D.

2009-01-01

An organism’s ability to detect and discriminate sensory inputs depends on the recent stimulus history. For example, perceptual detection thresholds for a brief tone can be elevated by as much as 50 dB when following a masking stimulus. Previous work suggests that such forward masking is not a direct result of peripheral neural adaptation; the central pathway apparently modifies the representation in a way that further attenuates the input’s response to short probe signals. Here, we show that much of this transformation is complete by the level of the inferior colliculus (IC). Single-neuron extracellular responses were recorded in the central nucleus of the awake marmoset IC. The threshold for a 20-ms probe tone presented at best frequency was determined for various masker-probe delays, over a range of masker SPLs and frequencies. The most striking aspect of the data was the increased potency of forward maskers as their SPL was increased, despite the fact that the excitatory response to the masker was often saturating or non-monotonic over the same range of levels. This led to probe thresholds at high masker levels that were almost always higher than those observed in the auditory nerve. Probe threshold shifts were not usually caused by a persistent excitatory response to the masker; instead we propose a wide dynamic-range inhibitory mechanism locked to sound offset as an explanation for several key aspects of the data. These findings further delineate the role of subcortical auditory processing in the generation of a context-dependent representation of ongoing acoustic scenes. PMID:19244530

Multiplexed lateral flow microarray assay for detection of citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis pv citri

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

Cary,; Bruce, R; Stubben, Christopher J

The invention provides highly sensitive and specific assays for the major citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis, including a field deployable multiplexed assay capable of rapidly assaying for both pathogens simultaneously. The assays are directed at particular gene targets derived from pathogenic strains that specifically cause the major citrus diseases of citrus variegated chlorosis (Xylella fastidiosa 9a5c) and citrus canker (Xanthomonas axonopodis pv citri). The citrus pathogen assays of the invention offer femtomole sensitivity, excellent linear dynamic range, and rapid and specific detection.

Photosensitive biosensor array system using optical addressing without an addressing circuit on array biochips

NASA Astrophysics Data System (ADS)

Ahn, Chang-Geun; Ah, Chil Seong; Kim, Tae-Youb; Park, Chan Woo; Yang, Jong-Heon; Kim, Ansoon; Sung, Gun Yong

2010-09-01

This paper introduces a photosensitive biosensor array system with a simple photodiode array that detects photocurrent changes caused by reactions between probe and target molecules. Using optical addressing, the addressing circuit on the array chip is removed for low-cost application, and real cell addressing is achieved using an externally located computer-controllable light-emitting diode array module. The fabricated biosensor array chip shows a good dynamic range of 1-100 ng/mL under prostate-specific antigen detection, with an on-chip resolution of roughly 1 ng/mL.

Design of the NDUV detection circuit for the NO concentration of the vehicle exhaust emissions

NASA Astrophysics Data System (ADS)

Zhang, Kai; Zhang, Yujun; He, Ying; You, Kun; Gao, Yanwei; Chen, Chen; Liu, Guohua; He, Chungui; Lu, Yibing; Liu, Wenqing

2016-10-01

With the increasing number of vehicles, the harm from NO to the environment becomes more and more prominent. So the monitoring of the NO concentration of the vehicle exhaust emissions is very important to assess the emission levels. In this paper, the NO detection system designing for vehicle exhaust emissions based on the non-dispersive ultraviolet principle (NDUV) has been researched. The technical indexes of the two-way modulation UV signal detection circuit are discussed in detail. And then a precision detection circuit is designed, which is composed of a trans-impedance amplifier and a lock-in amplifier, with which the output of the UV photoelectric detector can be amplified to a suitable voltage range, and the DC noise of the pre-stage amplifier is effectively removed by the lock-in amplifier. An experimental system was set up to test the designed circuit. To ensure the consistency of the two channels, the method of exchange calibration was adopted in the test. It's drawn that the designed circuit is of high SNR, measuring accuracy and a large dynamic range from the test results. The NO concentration detection limit of vehicle emissions can reach 1ppm, and the detection precision is +/-15ppm.

A new microfluidic approach for the one-step capture, amplification and label-free quantification of bacteria from raw samples† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc03880h Click here for additional data file. Click here for additional data file. Click here for additional data file. Click here for additional data file. Click here for additional data file. Click here for additional data file.

PubMed Central

Pereiro, Iago; Bendali, Amel; Tabnaoui, Sanae; Alexandre, Lucile; Srbova, Jana; Bilkova, Zuzana; Deegan, Shane; Joshi, Lokesh; Viovy, Jean-Louis; Malaquin, Laurent

2017-01-01

A microfluidic method to specifically capture and detect infectious bacteria based on immunorecognition and proliferative power is presented. It involves a microscale fluidized bed in which magnetic and drag forces are balanced to retain antibody-functionalized superparamagnetic beads in a chamber during sample perfusion. Captured cells are then cultivated in situ by infusing nutritionally-rich medium. The system was validated by the direct one-step detection of Salmonella Typhimurium in undiluted unskimmed milk, without pre-treatment. The growth of bacteria induces an expansion of the fluidized bed, mainly due to the volume occupied by the newly formed bacteria. This expansion can be observed with the naked eye, providing simple low-cost detection of only a few bacteria and in a few hours. The time to expansion can also be measured with a low-cost camera, allowing quantitative detection down to 4 cfu (colony forming unit), with a dynamic range of 100 to 107 cfu ml–1 in 2 to 8 hours, depending on the initial concentration. This mode of operation is an equivalent of quantitative PCR, with which it shares a high dynamic range and outstanding sensitivity and specificity, operating at the live cell rather than DNA level. Specificity was demonstrated by controls performed in the presence of a 500× excess of non-pathogenic Lactococcus lactis. The system's versatility was demonstrated by its successful application to the detection and quantitation of Escherichia coli O157:H15 and Enterobacter cloacae. This new technology allows fast, low-cost, portable and automated bacteria detection for various applications in food, environment, security and clinics. PMID:28626552

Long term monitoring of jaguars in the Cockscomb Basin Wildlife Sanctuary, Belize; Implications for camera trap studies of carnivores.

PubMed

Harmsen, Bart J; Foster, Rebecca J; Sanchez, Emma; Gutierrez-González, Carmina E; Silver, Scott C; Ostro, Linde E T; Kelly, Marcella J; Kay, Elma; Quigley, Howard

2017-01-01

In this study, we estimate life history parameters and abundance for a protected jaguar population using camera-trap data from a 14-year monitoring program (2002-2015) in Belize, Central America. We investigated the dynamics of this jaguar population using 3,075 detection events of 105 individual adult jaguars. Using robust design open population models, we estimated apparent survival and temporary emigration and investigated individual heterogeneity in detection rates across years. Survival probability was high and constant among the years for both sexes (φ = 0.78), and the maximum (conservative) age recorded was 14 years. Temporary emigration rate for the population was random, but constant through time at 0.20 per year. Detection probability varied between sexes, and among years and individuals. Heterogeneity in detection took the form of a dichotomy for males: those with consistently high detection rates, and those with low, sporadic detection rates, suggesting a relatively stable population of 'residents' consistently present and a fluctuating layer of 'transients'. Female detection was always low and sporadic. On average, twice as many males than females were detected per survey, and individual detection rates were significantly higher for males. We attribute sex-based differences in detection to biases resulting from social variation in trail-walking behaviour. The number of individual females detected increased when the survey period was extended from 3 months to a full year. Due to the low detection rates of females and the variable 'transient' male subpopulation, annual abundance estimates based on 3-month surveys had low precision. To estimate survival and monitor population changes in elusive, wide-ranging, low-density species, we recommend repeated surveys over multiple years; and suggest that continuous monitoring over multiple years yields even further insight into population dynamics of elusive predator populations.

Determination of propineb and its metabolites propylenethiourea and propylenediamine in banana and soil using gas chromatography with flame photometric detection and LC-MS/MS analysis.

PubMed

Song, Shiming; Wei, Jie; Chen, Zhaojie; Lei, Yuhao; Zhang, Yan; Deng, Cheng; Tan, Huihua; Li, Xuesheng

2018-03-04

A sensitive and specific method for the determination of propineb and its metabolites, propylenethiourea (PTU) and propylenediamine (PDA), using gas chromatography with flame photometric detection (GC-FPD) and LC-MS/MS was developed and validated. Propineb and its metabolite residue dynamics in supervised field trials under Good Agricultural Practice (GAP) conditions in banana and soil were studied. Recovery of propineb (as CS 2 ), PDA and PTU ranged from 75.3 to 115.4% with RSD (n = 5) of 1.3-11.1%. The limit of quantification (LOQ) of CS 2 , PDA and PTU ranged from 0.005 to 0.01 mg kg -1 , and the limit of detection (LOD) ranged from 0.0015 to 0.0033 mg kg -1 . Dissipation experiments showed that the half-life of propineb in banana and soil ranged from 4.4 to 13.3 days. PTU was found in banana with a half-life of 31.5-69.3 days, while levels of PDA were less than 0.01 mg kg -1 in banana and soil. It has been suggested that PTU is the major metabolite of propineb in banana. The method was demonstrated to be reliable and sensitive for the routine monitoring of propineb and its metabolites in banana and soil. It also serves as a reference for the detection and monitoring of dithiocarbamates (DTCs) residues and the evaluation of their metabolic pathway.

Detectable close-in planets around white dwarfs through late unpacking

NASA Astrophysics Data System (ADS)

Veras, Dimitri; Gänsicke, Boris T.

2015-02-01

Although 25-50 per cent of white dwarfs (WDs) display evidence for remnant planetary systems, their orbital architectures and overall sizes remain unknown. Vibrant close-in (≃1 R⊙) circumstellar activity is detected at WDs spanning many Gyr in age, suggestive of planets further away. Here we demonstrate how systems with 4 and 10 closely packed planets that remain stable and ordered on the main sequence can become unpacked when the star evolves into a WD and experience pervasive inward planetary incursions throughout WD cooling. Our full-lifetime simulations run for the age of the Universe and adopt main-sequence stellar masses of 1.5, 2.0 and 2.5 M⊙, which correspond to the mass range occupied by the progenitors of typical present-day WDs. These results provide (i) a natural way to generate an ever-changing dynamical architecture in post-main-sequence planetary systems, (ii) an avenue for planets to achieve temporary close-in orbits that are potentially detectable by transit photometry and (iii) a dynamical explanation for how residual asteroids might pollute particularly old WDs.

Optimizing Radiometric Fidelity to Enhance Aerial Image Change Detection Utilizing Digital Single Lens Reflex (DSLR) Cameras

NASA Astrophysics Data System (ADS)

Kerr, Andrew D.

Determining optimal imaging settings and best practices related to the capture of aerial imagery using consumer-grade digital single lens reflex (DSLR) cameras, should enable remote sensing scientists to generate consistent, high quality, and low cost image data sets. Radiometric optimization, image fidelity, image capture consistency and repeatability were evaluated in the context of detailed image-based change detection. The impetus for this research is in part, a dearth of relevant, contemporary literature, on the utilization of consumer grade DSLR cameras for remote sensing, and the best practices associated with their use. The main radiometric control settings on a DSLR camera, EV (Exposure Value), WB (White Balance), light metering, ISO, and aperture (f-stop), are variables that were altered and controlled over the course of several image capture missions. These variables were compared for their effects on dynamic range, intra-frame brightness variation, visual acuity, temporal consistency, and the detectability of simulated cracks placed in the images. This testing was conducted from a terrestrial, rather than an airborne collection platform, due to the large number of images per collection, and the desire to minimize inter-image misregistration. The results point to a range of slightly underexposed image exposure values as preferable for change detection and noise minimization fidelity. The makeup of the scene, the sensor, and aerial platform, influence the selection of the aperture and shutter speed which along with other variables, allow for estimation of the apparent image motion (AIM) motion blur in the resulting images. The importance of the image edges in the image application, will in part dictate the lowest usable f-stop, and allow the user to select a more optimal shutter speed and ISO. The single most important camera capture variable is exposure bias (EV), with a full dynamic range, wide distribution of DN values, and high visual contrast and acuity occurring around -0.7 to -0.3EV exposure bias. The ideal values for sensor gain, was found to be ISO 100, with ISO 200 a less desirable. This study offers researchers a better understanding of the effects of camera capture settings on RSI pairs and their influence on image-based change detection.

Scaling and universality in heart rate variability distributions

NASA Technical Reports Server (NTRS)

Rosenblum, M. G.; Peng, C. K.; Mietus, J. E.; Havlin, S.; Stanley, H. E.; Goldberger, A. L.

1998-01-01

We find that a universal homogeneous scaling form describes the distribution of cardiac variations for a group of healthy subjects, which is stable over a wide range of time scales. However, a similar scaling function does not exist for a group with a common cardiopulmonary instability associated with sleep apnea. Subtle differences in the distributions for the day- and night-phase dynamics for healthy subjects are detected.

Learning in Neural Networks: VLSI Implementation Strategies

NASA Technical Reports Server (NTRS)

Duong, Tuan Anh

1995-01-01

Fully-parallel hardware neural network implementations may be applied to high-speed recognition, classification, and mapping tasks in areas such as vision, or can be used as low-cost self-contained units for tasks such as error detection in mechanical systems (e.g. autos). Learning is required not only to satisfy application requirements, but also to overcome hardware-imposed limitations such as reduced dynamic range of connections.

Scaling and universality in heart rate variability distributions

NASA Astrophysics Data System (ADS)

Ivanov, P. Ch; Rosenblum, M. G.; Peng, C.-K.; Mietus, J. E.; Havlin, S.; Stanley, H. E.; Goldberger, A. L.

We find that a universal homogeneous scaling form describes the distributions of cardiac variations for a group of healthy subjects, which is stable over a wide range of time scales. However, a similar scaling function does not exist for a group with a common cardiopulmonary instability associated with sleep apnea. Subtle differences in the distributions for the day- and night-phase dynamics for healthy subjects are detected.

Comparison of LiDAR-derived data and high resolution true color imagery for extracting urban forest cover

Treesearch

Aaron E. Maxwell; Adam C. Riley; Paul Kinder

2013-01-01

Remote sensing has many applications in forestry. Light detection and ranging (LiDAR) and high resolution aerial photography have been investigated as means to extract forest data, such as biomass, timber volume, stand dynamics, and gap characteristics. LiDAR return intensity data are often overlooked as a source of input raster data for thematic map creation. We...

Specific 13C labeling of leucine, valine and isoleucine methyl groups for unambiguous detection of long-range restraints in protein solid-state NMR studies.

PubMed

Fasshuber, Hannes Klaus; Demers, Jean-Philippe; Chevelkov, Veniamin; Giller, Karin; Becker, Stefan; Lange, Adam

2015-03-01

Here we present an isotopic labeling strategy to easily obtain unambiguous long-range distance restraints in protein solid-state NMR studies. The method is based on the inclusion of two biosynthetic precursors in the bacterial growth medium, α-ketoisovalerate and α-ketobutyrate, leading to the production of leucine, valine and isoleucine residues that are exclusively (13)C labeled on methyl groups. The resulting spectral simplification facilitates the collection of distance restraints, the verification of carbon chemical shift assignments and the measurement of methyl group dynamics. This approach is demonstrated on the type-three secretion system needle of Shigella flexneri, where 49 methyl-methyl and methyl-nitrogen distance restraints including 10 unambiguous long-range distance restraints could be collected. By combining this labeling scheme with ultra-fast MAS and proton detection, the assignment of methyl proton chemical shifts was achieved. Copyright © 2015 Elsevier Inc. All rights reserved.

Detecting nonlinearity and chaos in epidemic data

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

Ellner, S.; Gallant, A.R.; Theiler, J.

1993-08-01

Historical data on recurrent epidemics have been central to the debate about the prevalence of chaos in biological population dynamics. Schaffer and Kot who first recognized that the abundance and accuracy of disease incidence data opened the door to applying a range of methods for detecting chaos that had been devised in the early 1980`s. Using attractor reconstruction, estimates of dynamical invariants, and comparisons between data and simulation of SEIR models, the ``case for chaos in childhood epidemics`` was made through a series of influential papers beginning in the mid 1980`s. The proposition that the precise timing and magnitude ofmore » epidemic outbreaks are deterministic but chaotic is appealing, since it raises the hope of finding determinism and simplicity beneath the apparently stochastic and complicated surface of the data. The initial enthusiasm for methods of detecting chaos in data has been followed by critical re-evaluations of their limitations. Early hopes of a ``one size fits all`` algorithm to diagnose chaos vs. noise in any data set have given way to a recognition that a variety of methods must be used, and interpretation of results must take into account the limitations of each method and the imperfections of the data. Our goals here are to outline some newer methods for detecting nonlinearity and chaos that have a solid statistical basis and are suited to epidemic data, and to begin a re-evaluation of the claims for nonlinear dynamics and chaos in epidemics using these newer methods. We also identify features of epidemic data that create problems for the older, better known methods of detecting chaos. When we ask ``are epidemics nonlinear?``, we are not questioning the existence of global nonlinearities in epidemic dynamics, such as nonlinear transmission rates. Our question is whether the data`s deviations from an annual cyclic trend (which would reflect global nonlinearities) are described by a linear, noise-driven stochastic process.« less

Clustering Effects on Dynamics in Ionomer Solutions: A Neutron Spin Echo Insight

NASA Astrophysics Data System (ADS)

Perahia, Dvora; Wijesinghe, Sidath; Senanayake, Manjula; Wickramasinghe, Anuradhi; Mohottalalage, Supun S.; Ohl, Michael

Ionizable blocks in ionomers associate into aggregates serving as physical cross-links and concurrently form transport pathways. The dynamics of ionomers underline their functionality. Incorporating small numbers of ionic groups into polymers significantly constraint their dynamics. Recent computational studies demonstrated a direct correlation between ionic cluster morphology and polymer dynamics. Here using neutron spin echo, we probe the segmental dynamics of polystyrene sulfonate (PSS) as the degree of sulfonation of the PSS and the solution dielectrics are varied. Specifically, 20Wt% PSS of 11,000 g/mol with polydispersity of 1.02 with 3% and 9% sulfonation were studies in toluene (dielectric constant ɛ = 2.8), a good solvent for polystyrene, and with 5Wt% of ethanol (ɛ = 24.3l) added. The dynamic structure factor S(q,t) was analyzed with a single exponential except for a limited q range where two time constants associated with constraint and mobile segments were detected. S(q,t) exhibits several distinctive time and length scales for the dynamics with a crossover appearing at the length scale of the ionic clusters. NSF DMR 1611136.

Complex regression Doppler optical coherence tomography

NASA Astrophysics Data System (ADS)

Elahi, Sahar; Gu, Shi; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

2018-04-01

We introduce a new method to measure Doppler shifts more accurately and extend the dynamic range of Doppler optical coherence tomography (OCT). The two-point estimate of the conventional Doppler method is replaced with a regression that is applied to high-density B-scans in polar coordinates. We built a high-speed OCT system using a 1.68-MHz Fourier domain mode locked laser to acquire high-density B-scans (16,000 A-lines) at high enough frame rates (˜100 fps) to accurately capture the dynamics of the beating embryonic heart. Flow phantom experiments confirm that the complex regression lowers the minimum detectable velocity from 12.25 mm / s to 374 μm / s, whereas the maximum velocity of 400 mm / s is measured without phase wrapping. Complex regression Doppler OCT also demonstrates higher accuracy and precision compared with the conventional method, particularly when signal-to-noise ratio is low. The extended dynamic range allows monitoring of blood flow over several stages of development in embryos without adjusting the imaging parameters. In addition, applying complex averaging recovers hidden features in structural images.

A fault diagnosis scheme for planetary gearboxes using modified multi-scale symbolic dynamic entropy and mRMR feature selection

NASA Astrophysics Data System (ADS)

Li, Yongbo; Yang, Yuantao; Li, Guoyan; Xu, Minqiang; Huang, Wenhu

2017-07-01

Health condition identification of planetary gearboxes is crucial to reduce the downtime and maximize productivity. This paper aims to develop a novel fault diagnosis method based on modified multi-scale symbolic dynamic entropy (MMSDE) and minimum redundancy maximum relevance (mRMR) to identify the different health conditions of planetary gearbox. MMSDE is proposed to quantify the regularity of time series, which can assess the dynamical characteristics over a range of scales. MMSDE has obvious advantages in the detection of dynamical changes and computation efficiency. Then, the mRMR approach is introduced to refine the fault features. Lastly, the obtained new features are fed into the least square support vector machine (LSSVM) to complete the fault pattern identification. The proposed method is numerically and experimentally demonstrated to be able to recognize the different fault types of planetary gearboxes.

Investigation of complexity dynamics in a DC glow discharge magnetized plasma using recurrence quantification analysis

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

Mitra, Vramori; Sarma, Bornali; Sarma, Arun

Recurrence is an ubiquitous feature which provides deep insights into the dynamics of real dynamical systems. A suitable tool for investigating recurrences is recurrence quantification analysis (RQA). It allows, e.g., the detection of regime transitions with respect to varying control parameters. We investigate the complexity of different coexisting nonlinear dynamical regimes of the plasma floating potential fluctuations at different magnetic fields and discharge voltages by using recurrence quantification variables, in particular, DET, L{sub max}, and Entropy. The recurrence analysis reveals that the predictability of the system strongly depends on discharge voltage. Furthermore, the persistent behaviour of the plasma time seriesmore » is characterized by the Detrended fluctuation analysis technique to explore the complexity in terms of long range correlation. The enhancement of the discharge voltage at constant magnetic field increases the nonlinear correlations; hence, the complexity of the system decreases, which corroborates the RQA analysis.« less

Comparison of direct 13C and indirect 1H-[13C] MR detection methods for the study of dynamic metabolic turnover in the human brain

NASA Astrophysics Data System (ADS)

Chen, Hao; De Feyter, Henk M.; Brown, Peter B.; Rothman, Douglas L.; Cai, Shuhui; de Graaf, Robin A.

2017-10-01

A wide range of direct 13C and indirect 1H-[13C] MR detection methods exist to probe dynamic metabolic pathways in the human brain. Choosing an optimal detection method is difficult as sequence-specific features regarding spatial localization, broadband decoupling, spectral resolution, power requirements and sensitivity complicate a straightforward comparison. Here we combine density matrix simulations with experimentally determined values for intrinsic 1H and 13C sensitivity, T1 and T2 relaxation and transmit efficiency to allow selection of an optimal 13C MR detection method for a given application and magnetic field. The indirect proton-observed, carbon-edited (POCE) detection method provides the highest accuracy at reasonable RF power deposition both at 4 T and 7 T. The various polarization transfer methods all have comparable performances, but may become infeasible at 7 T due to the high RF power deposition. 2D MR methods have limited value for the metabolites considered (primarily glutamate, glutamine and γ-amino butyric acid (GABA)), but may prove valuable when additional information can be extracted, such as isotopomers or lipid composition. While providing the lowest accuracy, the detection of non-protonated carbons is the simplest to implement with the lowest RF power deposition. The magnetic field homogeneity is one of the most important parameters affecting the detection accuracy for all metabolites and all acquisition methods.

Stereo Image Dense Matching by Integrating Sift and Sgm Algorithm

NASA Astrophysics Data System (ADS)

Zhou, Y.; Song, Y.; Lu, J.

2018-05-01

Semi-global matching(SGM) performs the dynamic programming by treating the different path directions equally. It does not consider the impact of different path directions on cost aggregation, and with the expansion of the disparity search range, the accuracy and efficiency of the algorithm drastically decrease. This paper presents a dense matching algorithm by integrating SIFT and SGM. It takes the successful matching pairs matched by SIFT as control points to direct the path in dynamic programming with truncating error propagation. Besides, matching accuracy can be improved by using the gradient direction of the detected feature points to modify the weights of the paths in different directions. The experimental results based on Middlebury stereo data sets and CE-3 lunar data sets demonstrate that the proposed algorithm can effectively cut off the error propagation, reduce disparity search range and improve matching accuracy.

A terahertz EO detector with large dynamical range, high modulation depth and signal-noise ratio

NASA Astrophysics Data System (ADS)

Pan, Xinjian; Cai, Yi; Zeng, Xuanke; Zheng, Shuiqin; Li, Jingzhen; Xu, Shixiang

2017-05-01

The paper presents a novel design for terahertz (THz) free-space time domain electro-optic (EO) detection where the static birefringent phases of the two balanced arms are set close to zero but opposite to each other. Our theoretical and numerical analyses show this design has much stronger ability to cancel the optical background noise than both THz ellipsometer and traditional crossed polarizer geometry (CPG). Its optical modulation depth is about twice as high as that of traditional CPG, but about ten times as high as that of THz ellipsometer. As for the dynamical range, our improved design is comparable to the THz ellipsometer but obviously larger than the traditional CPG. Some experiments for comparing our improved CPG with traditional CPG agree well with the corresponding theoretical predictions. Our experiments also show that the splitting ratio of the used non-polarization beam splitter is critical for the performance of our design.

An extrinsic fiber Fabry-Perot interferometer for dynamic displacement measurement

NASA Astrophysics Data System (ADS)

Pullteap, S.; Seat, H. C.

2015-03-01

A versatile fiber interferometer was proposed for high precision measurement. The sensor exploited a double-cavity within the unique sensing arm of an extrinsic-type fiber Fabry-Perot interferometer to produce the quadrature phase-shifted interference fringes. Interference signal processing was carried out using a modified zero-crossing (fringe) counting technique to demodulate two sets of fringes. The fiber interferometer has been successfully employed for dynamic displacement measurement under different displacement profiles over a range of 0.7 μm to 140 μm. A dedicated computer incorporating the demodulation algorithm was next used to interpret these detected data as well as plot the displacement information with a resolution of λ/64. A commercial displacement sensor was employed for comparison purposes with the experimental data obtained from the fiber interferometer as well as to gauge its performance, resulting in the maximum error of 2.8% over the entire displacement range studied.

Lattice dynamics of BaFe 2 X 3 ( X = S , Se ) compounds

DOE PAGES

Popović, Z. V.; Šćepanović, M.; Lazarević, N.; ...

2015-02-27

We present the Raman scattering spectra of the S=2 spin ladder compounds BaFe₂X₃ (X=S,Se) in a temperature range between 20 and 400 K. Although the crystal structures of these two compounds are both orthorhombic and very similar, they are not isostructural. The unit cell of BaFe₂S₃ (BaFe₂Se₃) is base-centered Cmcm (primitive Pnma), giving 18 (36) modes to be observed in the Raman scattering experiment. We have detected almost all Raman active modes, predicted by factor group analysis, which can be observed from the cleavage planes of these compounds. Assignment of the observed Raman modes of BaFe₂S(Se)₃ is supported by themore » lattice dynamics calculations. The antiferromagnetic long-range spin ordering in BaFe₂Se₃ below T N=255K leaves a fingerprint both in the A 1g and B 3g phonon mode linewidth and energy.« less

Predicting dynamic range and intensity discrimination for electrical pulse-train stimuli using a stochastic auditory nerve model: the effects of stimulus noise.

PubMed

Xu, Yifang; Collins, Leslie M

2005-06-01

This work investigates dynamic range and intensity discrimination for electrical pulse-train stimuli that are modulated by noise using a stochastic auditory nerve model. Based on a hypothesized monotonic relationship between loudness and the number of spikes elicited by a stimulus, theoretical prediction of the uncomfortable level has previously been determined by comparing spike counts to a fixed threshold, Nucl. However, no specific rule for determining Nucl has been suggested. Our work determines the uncomfortable level based on the excitation pattern of the neural response in a normal ear. The number of fibers corresponding to the portion of the basilar membrane driven by a stimulus at an uncomfortable level in a normal ear is related to Nucl at an uncomfortable level of the electrical stimulus. Intensity discrimination limens are predicted using signal detection theory via the probability mass function of the neural response and via experimental simulations. The results show that the uncomfortable level for pulse-train stimuli increases slightly as noise level increases. Combining this with our previous threshold predictions, we hypothesize that the dynamic range for noise-modulated pulse-train stimuli should increase with additive noise. However, since our predictions indicate that intensity discrimination under noise degrades, overall intensity coding performance may not improve significantly.

QLog Solar-Cell Mode Photodiode Logarithmic CMOS Pixel Using Charge Compression and Readout †

PubMed Central

Ni, Yang

2018-01-01

In this paper, we present a new logarithmic pixel design currently under development at New Imaging Technologies SA (NIT). This new logarithmic pixel design uses charge domain logarithmic signal compression and charge-transfer-based signal readout. This structure gives a linear response in low light conditions and logarithmic response in high light conditions. The charge transfer readout efficiently suppresses the reset (KTC) noise by using true correlated double sampling (CDS) in low light conditions. In high light conditions, thanks to charge domain logarithmic compression, it has been demonstrated that 3000 electrons should be enough to cover a 120 dB dynamic range with a mobile phone camera-like signal-to-noise ratio (SNR) over the whole dynamic range. This low electron count permits the use of ultra-small floating diffusion capacitance (sub-fF) without charge overflow. The resulting large conversion gain permits a single photon detection capability with a wide dynamic range without a complex sensor/system design. A first prototype sensor with 320 × 240 pixels has been implemented to validate this charge domain logarithmic pixel concept and modeling. The first experimental results validate the logarithmic charge compression theory and the low readout noise due to the charge-transfer-based readout. PMID:29443903

QLog Solar-Cell Mode Photodiode Logarithmic CMOS Pixel Using Charge Compression and Readout.

PubMed

Ni, Yang

2018-02-14

In this paper, we present a new logarithmic pixel design currently under development at New Imaging Technologies SA (NIT). This new logarithmic pixel design uses charge domain logarithmic signal compression and charge-transfer-based signal readout. This structure gives a linear response in low light conditions and logarithmic response in high light conditions. The charge transfer readout efficiently suppresses the reset (KTC) noise by using true correlated double sampling (CDS) in low light conditions. In high light conditions, thanks to charge domain logarithmic compression, it has been demonstrated that 3000 electrons should be enough to cover a 120 dB dynamic range with a mobile phone camera-like signal-to-noise ratio (SNR) over the whole dynamic range. This low electron count permits the use of ultra-small floating diffusion capacitance (sub-fF) without charge overflow. The resulting large conversion gain permits a single photon detection capability with a wide dynamic range without a complex sensor/system design. A first prototype sensor with 320 × 240 pixels has been implemented to validate this charge domain logarithmic pixel concept and modeling. The first experimental results validate the logarithmic charge compression theory and the low readout noise due to the charge-transfer-based readout.

Introduction to State Estimation of High-Rate System Dynamics.

PubMed

Hong, Jonathan; Laflamme, Simon; Dodson, Jacob; Joyce, Bryan

2018-01-13

Engineering systems experiencing high-rate dynamic events, including airbags, debris detection, and active blast protection systems, could benefit from real-time observability for enhanced performance. However, the task of high-rate state estimation is challenging, in particular for real-time applications where the rate of the observer's convergence needs to be in the microsecond range. This paper identifies the challenges of state estimation of high-rate systems and discusses the fundamental characteristics of high-rate systems. A survey of applications and methods for estimators that have the potential to produce accurate estimations for a complex system experiencing highly dynamic events is presented. It is argued that adaptive observers are important to this research. In particular, adaptive data-driven observers are advantageous due to their adaptability and lack of dependence on the system model.

Comparison of full-field interferometric measurement techniques applied to small vibration amplitudes determination

NASA Astrophysics Data System (ADS)

Styk, Adam

2014-07-01

Classical time-averaging and stroboscopic interferometry are widely used for MEMS/MOEMS dynamic behavior investigations. Unfortunately both methods require an amplitude magnitude of at least 0.19λ to be able to detect resonant frequency of the object. Moreover the precision of measurement is limited. That puts strong constrains on the type of element to be tested. In this paper the comparison of two methods of microobject vibration measurements that overcome aforementioned problems are presented. Both methods maintain high speed measurement time and extend the range of amplitudes to be measured (below 0.19λ), moreover can be easily applied to MEMS/MOEMS dynamic parameters measurements.

Cooperativity and Heterogeneity in Plastic Crystals Studied by Nonlinear Dielectric Spectroscopy

NASA Astrophysics Data System (ADS)

Michl, M.; Bauer, Th.; Lunkenheimer, P.; Loidl, A.

2015-02-01

The glassy dynamics of plastic-crystalline cyclo-octanol and ortho-carborane, where only the molecular reorientational degrees of freedom freeze without long-range order, is investigated by nonlinear dielectric spectroscopy. Marked differences to canonical glass formers show up: While molecular cooperativity governs the glassy freezing, it leads to a much weaker slowing down of molecular dynamics than in supercooled liquids. Moreover, the observed nonlinear effects cannot be explained with the same heterogeneity scenario recently applied to canonical glass formers. This supports ideas that molecular relaxation in plastic crystals may be intrinsically nonexponential. Finally, no nonlinear effects were detected for the secondary processes in cyclo-octanol.

Temperature-Dependent Detectivity of Near-Infrared Organic Bulk Heterojunction Photodiodes.

PubMed

Wu, Zhenghui; Yao, Weichuan; London, Alexander E; Azoulay, Jason D; Ng, Tse Nga

2017-01-18

Bulk heterojunction photodiodes are fabricated using a new donor-acceptor polymer with a near-infrared absorption edge at 1.2 μm, achieving a detectivity up to 10 12 Jones at a wavelength of 1 μm and an excellent linear dynamic range of 86 dB. The photodiode detectivity is maximized by operating at zero bias to suppress dark current, while a thin 175 nm active layer is used to facilitate charge collection without reverse bias. Analysis of the temperature dependence of the dark current and spectral response demonstrates a 2.8-fold increase in detectivity as the temperature was lowered from 44 to -12 °C, a relatively small change when compared to that of inorganic-based devices. The near-infrared photodiode shows a switching speed reaching up to 120 μs without an external bias. An application using our NIR photodiode to detect arterial pulses of a fingertip is demonstrated.

Leveraging zinc interstitials and oxygen vacancies for sensitive biomolecule detection through selective surface functionalization

NASA Astrophysics Data System (ADS)

Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Chaudhry, Shajee; Prasad, Shalini

2015-03-01

In this study, functionally engineered EIS technique was implemented to investigate the influence of surface functionalization on sensitivity of biomolecule detection using nanostructured ZnO platform. Organic molecules with thiol and carboxylic functional groups were chosen to control biomolecule immobilization on zinc and oxygen-terminated 2D planar and 1D nanostructured ZnO surfaces. The amount of functionalization and its influence on charge perturbations at the ZnO-electrolyte interface were studied using fluorescence and EIS measurements. We observed the dependence of charge transfer on both the polarity of platform and concentration of cross-linker molecules. Such selectively modified surfaces were used for detection of cortisol, a major stress indicator. Results demonstrated preferential binding of thiol groups to Zn terminations and thus leveraging ZnO interstitials increases the sensitivity of detection over larger dynamic range with detection limit at 10fg/mL.

Messenger RNA Detection in Leukemia Cell lines by Novel Metal-Tagged in situ Hybridization using Inductively Coupled Plasma Mass Spectrometry.

PubMed

Ornatsky, Olga I; Baranov, Vladimir I; Bandura, Dmitry R; Tanner, Scott D; Dick, John

2006-01-01

Conventional gene expression profiling relies on using fluorescent detection of hybridized probes. Physical characteristics of fluorophores impose limitations on achieving a highly multiplex gene analysis of single cells. Our work demonstrates the feasibility of using metal-tagged in situ hybridization for mRNA detection by inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS as an analytical detector has a number of unique and relevant properties: 1) metals and their stable isotopes generate non-overlapping distinct signals that can be detected simultaneously; 2) these signals can be measured over a wide dynamic range; 3) ICP-MS is quantitative and very sensitive. We used commercial antibodies conjugated to europium (Eu) and gold together with biotinylated oligonucleotide probes reacted with terbium-labeled streptavidin to demonstrate simultaneous mRNA and protein detection by ICP-MS in leukemia cells.

Messenger RNA Detection in Leukemia Cell lines by Novel Metal-Tagged in situ Hybridization using Inductively Coupled Plasma Mass Spectrometry

PubMed Central

Ornatsky, Olga I.; Baranov, Vladimir I.; Bandura, Dmitry R.; Tanner, Scott D.; Dick, John

2006-01-01

Conventional gene expression profiling relies on using fluorescent detection of hybridized probes. Physical characteristics of fluorophores impose limitations on achieving a highly multiplex gene analysis of single cells. Our work demonstrates the feasibility of using metal-tagged in situ hybridization for mRNA detection by inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS as an analytical detector has a number of unique and relevant properties: 1) metals and their stable isotopes generate non-overlapping distinct signals that can be detected simultaneously; 2) these signals can be measured over a wide dynamic range; 3) ICP-MS is quantitative and very sensitive. We used commercial antibodies conjugated to europium (Eu) and gold together with biotinylated oligonucleotide probes reacted with terbium-labeled streptavidin to demonstrate simultaneous mRNA and protein detection by ICP-MS in leukemia cells. PMID:23662035

Quasi-dynamic mode of nanomembranes for time-of-flight mass spectrometry of proteins.

PubMed

Park, Jonghoo; Kim, Hyunseok; Blick, Robert H

2012-04-21

Mechanical resonators realized on the nano-scale by now offer applications in mass-sensing of biomolecules with extraordinary sensitivity. The general idea is that perfect mechanical biosensors should be of extremely small size to achieve zeptogram sensitivity in weighing single molecules similar to a balance. However, the small scale and long response time of weighing biomolecules with a cantilever restrict their usefulness as a high-throughput method. Commercial mass spectrometry (MS) such as electro-spray ionization (ESI)-MS and matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF)-MS are the gold standards to which nanomechanical resonators have to live up to. These two methods rely on the ionization and acceleration of biomolecules and the following ion detection after a mass selection step, such as time-of-flight (TOF). Hence, the spectrum is typically represented in m/z, i.e. the mass to ionization charge ratio. Here, we describe the feasibility and mass range of detection of a new mechanical approach for ion detection in time-of-flight mass spectrometry, the principle of which is that the impinging ion packets excite mechanical oscillations in a silicon nitride nanomembrane. These mechanical oscillations are henceforth detected via field emission of electrons from the nanomembrane. Ion detection is demonstrated in MALDI-TOF analysis over a broad range with angiotensin, bovine serum albumin (BSA), and an equimolar protein mixture of insulin, BSA, and immunoglobulin G (IgG). We find an unprecedented mass range of operation of the nanomembrane detector.

Performance of Laser Megajoule’s x-ray streak camera

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

Zuber, C., E-mail: celine.zuber@cea.fr; Bazzoli, S.; Brunel, P.

2016-11-15

A prototype of a picosecond x-ray streak camera has been developed and tested by Commissariat à l’Énergie Atomique et aux Énergies Alternatives to provide plasma-diagnostic support for the Laser Megajoule. We report on the measured performance of this streak camera, which almost fulfills the requirements: 50-μm spatial resolution over a 15-mm field in the photocathode plane, 17-ps temporal resolution in a 2-ns timebase, a detection threshold lower than 625 nJ/cm{sup 2} in the 0.05–15 keV spectral range, and a dynamic range greater than 100.

ISS Destiny Laboratory Smoke Detection Model

NASA Technical Reports Server (NTRS)

Brooker, John E.; Urban, David L.; Ruff, Gary A.

2007-01-01

Smoke transport and detection were modeled numerically in the ISS Destiny module using the NIST, Fire Dynamics Simulator code. The airflows in Destiny were modeled using the existing flow conditions and the module geometry included obstructions that simulate the currently installed hardware on orbit. The smoke source was modeled as a 0.152 by 0.152 m region that emitted smoke particulate ranging from 1.46 to 8.47 mg/s. In the module domain, the smoke source was placed in the center of each Destiny rack location and the model was run to determine the time required for the two smoke detectors to alarm. Overall the detection times were dominated by the circumferential flow, the axial flow from the intermodule ventilation and the smoke source strength.

An approach to spin-resolved molecular gas microscopy

NASA Astrophysics Data System (ADS)

Covey, Jacob P.; De Marco, Luigi; Acevedo, Óscar L.; Rey, Ana Maria; Ye, Jun

2018-04-01

Ultracold polar molecules are an ideal platform for studying many-body physics with long-range dipolar interactions. Experiments in this field have progressed enormously, and several groups are pursuing advanced apparatus for manipulation of molecules with electric fields as well as single-atom-resolved in situ detection. Such detection has become ubiquitous for atoms in optical lattices and tweezer arrays, but has yet to be demonstrated for ultracold polar molecules. Here we present a proposal for the implementation of site-resolved microscopy for polar molecules, and specifically discuss a technique for spin-resolved molecular detection. We use numerical simulation of spin dynamics of lattice-confined polar molecules to show how such a scheme would be of utility in a spin-diffusion experiment.

A distributed scheme to manage the dynamic coexistence of IEEE 802.15.4-based health-monitoring WBANs.

PubMed

Deylami, Mohammad N; Jovanov, Emil

2014-01-01

The overlap of transmission ranges between wireless networks as a result of mobility is referred to as dynamic coexistence. The interference caused by coexistence may significantly affect the performance of wireless body area networks (WBANs) where reliability is particularly critical for health monitoring applications. In this paper, we analytically study the effects of dynamic coexistence on the operation of IEEE 802.15.4-based health monitoring WBANs. The current IEEE 802.15.4 standard lacks mechanisms for effectively managing the coexistence of mobile WBANs. Considering the specific characteristics and requirements of health monitoring WBANs, we propose the dynamic coexistence management (DCM) mechanism to make IEEE 802.15.4-based WBANs able to detect and mitigate the harmful effects of coexistence. We assess the effectiveness of this scheme using extensive OPNET simulations. Our results indicate that DCM improves the successful transmission rates of dynamically coexisting WBANs by 20%-25% for typical medical monitoring applications.

Colloquium: Non-Markovian dynamics in open quantum systems

NASA Astrophysics Data System (ADS)

Breuer, Heinz-Peter; Laine, Elsi-Mari; Piilo, Jyrki; Vacchini, Bassano

2016-04-01

The dynamical behavior of open quantum systems plays a key role in many applications of quantum mechanics, examples ranging from fundamental problems, such as the environment-induced decay of quantum coherence and relaxation in many-body systems, to applications in condensed matter theory, quantum transport, quantum chemistry, and quantum information. In close analogy to a classical Markovian stochastic process, the interaction of an open quantum system with a noisy environment is often modeled phenomenologically by means of a dynamical semigroup with a corresponding time-independent generator in Lindblad form, which describes a memoryless dynamics of the open system typically leading to an irreversible loss of characteristic quantum features. However, in many applications open systems exhibit pronounced memory effects and a revival of genuine quantum properties such as quantum coherence, correlations, and entanglement. Here recent theoretical results on the rich non-Markovian quantum dynamics of open systems are discussed, paying particular attention to the rigorous mathematical definition, to the physical interpretation and classification, as well as to the quantification of quantum memory effects. The general theory is illustrated by a series of physical examples. The analysis reveals that memory effects of the open system dynamics reflect characteristic features of the environment which opens a new perspective for applications, namely, to exploit a small open system as a quantum probe signifying nontrivial features of the environment it is interacting with. This Colloquium further explores the various physical sources of non-Markovian quantum dynamics, such as structured environmental spectral densities, nonlocal correlations between environmental degrees of freedom, and correlations in the initial system-environment state, in addition to developing schemes for their local detection. Recent experiments addressing the detection, quantification, and control of non-Markovian quantum dynamics are also briefly discussed.

The fresnel interferometric imager

NASA Astrophysics Data System (ADS)

Koechlin, Laurent; Serre, Denis; Deba, Paul; Pelló, Roser; Peillon, Christelle; Duchon, Paul; Gomez de Castro, Ana Ines; Karovska, Margarita; Désert, Jean-Michel; Ehrenreich, David; Hebrard, Guillaume; Lecavelier Des Etangs, Alain; Ferlet, Roger; Sing, David; Vidal-Madjar, Alfred

2009-03-01

The Fresnel Interferometric Imager has been proposed to the European Space Agency (ESA) Cosmic Vision plan as a class L mission. This mission addresses several themes of the CV Plan: Exoplanet study, Matter in extreme conditions, and The Universe taking shape. This paper is an abridged version of the original ESA proposal. We have removed most of the technical and financial issues, to concentrate on the instrumental design and astrophysical missions. The instrument proposed is an ultra-lightweight telescope, featuring a novel optical concept based on diffraction focussing. It yields high dynamic range images, while releasing constraints on positioning and manufacturing of the main optical elements. This concept should open the way to very large apertures in space. In this two spacecraft formation-flying instrument, one spacecraft holds the focussing element: the Fresnel interferometric array; the other spacecraft holds the field optics, focal instrumentation, and detectors. The Fresnel array proposed here is a 3.6 ×3.6 m square opaque foil punched with 105 to 106 void “subapertures”. Focusing is achieved with no other optical element: the shape and positioning of the subapertures (holes in the foil) is responsible for beam combining by diffraction, and 5% to 10% of the total incident light ends up into a sharp focus. The consequence of this high number of subapertures is high dynamic range images. In addition, as it uses only a combination of vacuum and opaque material, this focussing method is potentially efficient over a very broad wavelength domain. The focal length of such diffractive focussing devices is wavelength dependent. However, this can be corrected. We have tested optically the efficiency of the chromatism correction on artificial sources (500 < λ < 750 nm): the images are diffraction limited, and the dynamic range measured on an artificial double source reaches 6.2 10 - 6. We have also validated numerical simulation algorithms for larger Fresnel interferometric arrays. These simulations yield a dynamic range (rejection factor) close to 10 - 8 for arrays such as the 3.6 m one we propose. A dynamic range of 10 - 8 allows detection of objects at contrasts as high as than 10 - 9 in most of the field. The astrophysical applications cover many objects in the IR, visible an UV domains. Examples are presented, taking advantage of the high angular resolution and dynamic range capabilities of this concept.

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

Barkaoui, Sami; Haddaoui, Marwa; Dhaouadi, Hassouna, E-mail: dhaouadihassouna@yahoo.fr

Nanostructured tricobalt tetraoxide, Co{sub 3}O{sub 4}, was hydrothermally synthesized starting from cobalt dichloride hexahydrate (CoCl{sub 2}·6H{sub 2}O) and urea (H{sub 2}NCONH{sub 2}) as precursor and polyethylene glycol-400 (PEG-400) as a structure-directing agent. Uniform urchin-like nanostructures were hydrothermally obtained at 150 °C for 16 h, and the Co{sub 3}O{sub 4} morphology did not collapse after a subsequent calcination at 300 °C for 2 h. XRD measurements indicated that the average sizes of Co{sub 3}O{sub 4} particles prior and after heating at 300 °C are 64 and 44 nm, respectively. This material has been successfully used for the nanostructuration of screen-printed carbonmore » electrodes (SPCEs) which were used for the sensitive electrochemical detection of hydrogen peroxide (H{sub 2}O{sub 2}). The sensor is endowed with a large dynamic range (0.1 to 50 µM) and a limit of detection of 0.145 µM. The as obtained results show that the Co{sub 3}O{sub 4} nanomaterial could be a candidate to be used as sensors for the detection of analytes. - Graphical abstract: The nanowires appear to have a common center and grow to the outside along the radial direction. - Highlights: • Nanostructured was hydrothermally prepared using PEG-400. • Uniform urchin-like Co{sub 3}O{sub 4} nanostructures were hydrothermally obtained. • X-ray diffraction showed a cubic structure after calcinations process. • Nanostructured Co{sub 3}O{sub 4} was used for the sensitive electrochemical detection of H{sub 2}O{sub 2.} • The sensor is endowed with a large dynamic range 0.1 to 50 µM.« less

Two-Channel SPR Sensor Combined Application of Polymer- and Vitreous-Clad Optic Fibers

PubMed Central

Wei, Yong; Su, Yudong; Liu, Chunlan; Nie, Xiangfei; Liu, Zhihai; Zhang, Yu; Zhang, Yonghui

2017-01-01

By combining a polymer-clad optic fiber and a vitreous-clad optic fiber, we proposed and fabricated a novel optic fiber surface plasmon resonance (SPR) sensor to conduct two-channel sensing at the same detection area. The traditional optic fiber SPR sensor has many disadvantages; for example, removing the cladding requires corrosion, operating it is dangerous, adjusting the dynamic response range is hard, and producing different resonance wavelengths in the sensing area to realize a multi-channel measurement is difficult. Therefore, in this paper, we skillfully used bare fiber grinding technology and reverse symmetry welding technology to remove the cladding in a multi-mode fiber and expose the evanescent field. On the basis of investigating the effect of the grinding angle on the dynamic range change of the SPR resonance valley wavelength and sensitivity, we combined polymer-clad fiber and vitreous-clad fiber by a smart design structure to realize at a single point a two-channel measurement fiber SPR sensor. In this paper, we obtained a beautiful spectral curve from a multi-mode fiber two-channel SPR sensor. In the detection range of the refractive rate between 1.333 RIU and 1.385 RIU, the resonance valley wavelength of channel Ⅰ shifted from 622 nm to 724 nm with a mean average sensitivity of 1961 nm/RIU and the resonance valley wavelength of channel Ⅱ shifted from 741 nm to 976 nm with a mean average sensitivity of 4519 nm/RIU. PMID:29232841

Dynamics of Vibrio with virulence genes detected in Pacific harbor seals (Phoca vitulina richardii) off California: implications for marine mammal health.

PubMed

Hughes, Stephanie N; Greig, Denise J; Miller, Woutrina A; Byrne, Barbara A; Gulland, Frances M D; Harvey, James T

2013-05-01

Given their coastal site fidelity and opportunistic foraging behavior, harbor seals (Phoca vitulina) may serve as sentinels for coastal ecosystem health. Seals using urbanized coastal habitat can acquire enteric bacteria, including Vibrio that may affect their health. To understand Vibrio dynamics in seals, demographic and environmental factors were tested for predicting potentially virulent Vibrio in free-ranging and stranded Pacific harbor seals (Phoca vitulina richardii) off California. Vibrio prevalence did not vary with season and was greater in free-ranging seals (29 %, n = 319) compared with stranded seals (17 %, n = 189). Of the factors tested, location, turbidity, and/or salinity best predicted Vibrio prevalence in free-ranging seals. The relationship of environmental factors with Vibrio prevalence differed by location and may be related to oceanographic or terrestrial contributions to water quality. Vibrio parahaemolyticus, Vibrio alginolyticus, and Vibrio cholerae were observed in seals, with V. cholerae found almost exclusively in stranded pups and yearlings. Additionally, virulence genes (trh and tdh) were detected in V. parahaemolyticus isolates. Vibrio cholerae isolates lacked targeted virulence genes, but were hemolytic. Three out of four stranded pups with V. parahaemolyticus (trh+ and/or tdh+) died in rehabilitation, but the role of Vibrio in causing mortality is unclear, and Vibrio expression of virulence genes should be investigated. Considering that humans share the environment and food resources with seals, potentially virulent Vibrio observed in seals also may be of concern to human health.

Two-Channel SPR Sensor Combined Application of Polymer- and Vitreous-Clad Optic Fibers.

PubMed

Wei, Yong; Su, Yudong; Liu, Chunlan; Nie, Xiangfei; Liu, Zhihai; Zhang, Yu; Zhang, Yonghui

2017-12-09

By combining a polymer-clad optic fiber and a vitreous-clad optic fiber, we proposed and fabricated a novel optic fiber surface plasmon resonance (SPR) sensor to conduct two-channel sensing at the same detection area. The traditional optic fiber SPR sensor has many disadvantages; for example, removing the cladding requires corrosion, operating it is dangerous, adjusting the dynamic response range is hard, and producing different resonance wavelengths in the sensing area to realize a multi-channel measurement is difficult. Therefore, in this paper, we skillfully used bare fiber grinding technology and reverse symmetry welding technology to remove the cladding in a multi-mode fiber and expose the evanescent field. On the basis of investigating the effect of the grinding angle on the dynamic range change of the SPR resonance valley wavelength and sensitivity, we combined polymer-clad fiber and vitreous-clad fiber by a smart design structure to realize at a single point a two-channel measurement fiber SPR sensor. In this paper, we obtained a beautiful spectral curve from a multi-mode fiber two-channel SPR sensor. In the detection range of the refractive rate between 1.333 RIU and 1.385 RIU, the resonance valley wavelength of channel Ⅰ shifted from 622 nm to 724 nm with a mean average sensitivity of 1961 nm/RIU and the resonance valley wavelength of channel Ⅱ shifted from 741 nm to 976 nm with a mean average sensitivity of 4519 nm/RIU.

A water-based fast integrated mobility spectrometer (WFIMS) with enhanced dynamic size range

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

Pinterich, Tamara; Spielman, Steven R.; Hering, Susanne

We developed a water-based fast integrated mobility spectrometer (WFIMS) with enhanced dynamic size range. The WFIMS builds on two established technologies: the fast integrated mobility spectrometer and laminar flow water-based condensation methodology. Inside WFIMS, particles of differing electrical mobility are separated in a drift tube and subsequently enlarged through water condensation. Particle size and concentration are measured via digital imaging at a frame rate of 10 Hz. When we measure particles of different mobilities simultaneously, the WFIMS resolves particle diameters ranging from 8 to 580 nm within 1 s or less. The performance of WFIMS was characterized with differential mobilitymore » analyzer (DMA) classified (NH 4) 2SO 2 particles with diameters ranging from 8 to 265 nm. The mean particle diameters measured by WFIMS were found to be in excellent agreement with DMA centroid diameters. Furthermore, detection efficiency of WFIMS was characterized using a condensation particle counter as a reference and is nearly 100% for particles with diameter greater than 8 nm. In general, measured and simulated WFIMS mobility resolutions are in good agreement. But, some deviations are observed at low particle mobilities, likely due to the non-idealities of the WFIMS electric field.« less

A water-based fast integrated mobility spectrometer (WFIMS) with enhanced dynamic size range

DOE PAGES

Pinterich, Tamara; Spielman, Steven R.; Hering, Susanne; ...

2017-06-08

We developed a water-based fast integrated mobility spectrometer (WFIMS) with enhanced dynamic size range. The WFIMS builds on two established technologies: the fast integrated mobility spectrometer and laminar flow water-based condensation methodology. Inside WFIMS, particles of differing electrical mobility are separated in a drift tube and subsequently enlarged through water condensation. Particle size and concentration are measured via digital imaging at a frame rate of 10 Hz. When we measure particles of different mobilities simultaneously, the WFIMS resolves particle diameters ranging from 8 to 580 nm within 1 s or less. The performance of WFIMS was characterized with differential mobilitymore » analyzer (DMA) classified (NH 4) 2SO 2 particles with diameters ranging from 8 to 265 nm. The mean particle diameters measured by WFIMS were found to be in excellent agreement with DMA centroid diameters. Furthermore, detection efficiency of WFIMS was characterized using a condensation particle counter as a reference and is nearly 100% for particles with diameter greater than 8 nm. In general, measured and simulated WFIMS mobility resolutions are in good agreement. But, some deviations are observed at low particle mobilities, likely due to the non-idealities of the WFIMS electric field.« less

Smartphone Cortex Controlled Real-Time Image Processing and Reprocessing for Concentration Independent LED Induced Fluorescence Detection in Capillary Electrophoresis.

PubMed

Szarka, Mate; Guttman, Andras

2017-10-17

We present the application of a smartphone anatomy based technology in the field of liquid phase bioseparations, particularly in capillary electrophoresis. A simple capillary electrophoresis system was built with LED induced fluorescence detection and a credit card sized minicomputer to prove the concept of real time fluorescent imaging (zone adjustable time-lapse fluorescence image processor) and separation controller. The system was evaluated by analyzing under- and overloaded aminopyrenetrisulfonate (APTS)-labeled oligosaccharide samples. The open source software based image processing tool allowed undistorted signal modulation (reprocessing) if the signal was inappropriate for the actual detection system settings (too low or too high). The novel smart detection tool for fluorescently labeled biomolecules greatly expands dynamic range and enables retrospective correction for injections with unsuitable signal levels without the necessity to repeat the analysis.

NBC detection in air and water

NASA Technical Reports Server (NTRS)

Hartley, Frank T.; Smith, Steven J.; McMurtry, Gary M.

2003-01-01

Participating in a Navy STTR project to develop a system capable of the 'real-time' detection and quanitification of nuclear, biological and chemical (NBC) warfare agents, and of related industrial chemicals including NBC agent synthesis by-products in water and in air immediately above the water's surface. This project uses JPL's Soft Ionization Membrane (SIM) technology which totally ionizes molecules without fragmentation (a process that can markedly improve the sensitivity and specificity of molecule compostition identification), and JPL's Rotating Field Mass Spectrometer (RFMS) technology which has large enough dynamic mass range to enable detection of nuclear materials as well as biological and chemical agents. This Navy project integrates these JPL Environmental Monitoring UnitS (REMUS) an autonomous underwater vehicle (AUV). It is anticipated that the REMUS AUV will be capable of 'real-time' detection and quantification of NBC warefare agents.

Optical Communications With A Geiger Mode APD Array

DTIC Science & Technology

2016-02-09

spurious fires from numerous sources, including crosstalk from other detectors in the same array . Additionally, after a 9 successful detection, the...be combined into arrays with large numbers of detectors , allowing for scaling of dynamic range with relatively little overhead on space and power...overall higher rate of dark counts than a single detector , this is more than compensated for by the extra detectors . A sufficiently large APD array could

A More Stringent Constraint on the Mass Ratio of Binary Neutron Star Merger GW170817

NASA Astrophysics Data System (ADS)

Gao, He; Cao, Zhoujian; Ai, Shunke; Zhang, Bing

2017-12-01

Recently, the LIGO–Virgo Collaborations reported their first detection of gravitational-wave (GW) signals from the low-mass compact binary merger GW170817, which is most likely due to a double neutron star (NS) merger. With the GW signals only, the chirp mass of the binary is precisely constrained to {1.188}-0.002+0.004 {M}ȯ , but the mass ratio is loosely constrained in the range 0.4–1, so that a very rough estimation of the individual NS masses (1.36 M ⊙ < M 1 < 2.26 M ⊙ and 0.86 M ⊙ < M 2 < 1.36 M ⊙) was obtained. Here, we propose that if one can constrain the dynamical ejecta mass through performing kilonova modeling of the optical/IR data, by utilizing an empirical relation between the dynamical ejecta mass and the mass ratio of NS binaries, one may place a more stringent constraint on the mass ratio of the system. For instance, considering that the red “kilonova” component is powered by the dynamical ejecta, we reach a tight constraint on the mass ratio in the range of 0.46–0.59. Alternatively, if the blue “kilonova” component is powered by the dynamical ejecta, the mass ratio would be constrained in the range of 0.53–0.67. Overall, such a multi-messenger approach could narrow down the mass ratio of GW170817 system to the range of 0.46–0.67, which gives a more precise estimation of the individual NS mass than pure GW signal analysis, i.e., 1.61 M ⊙ < M 1 < 2.11 M ⊙ and 0.90 M ⊙ < M 2 < 1.16 M ⊙.

Temperature dependence in magnetic particle imaging

NASA Astrophysics Data System (ADS)

Wells, James; Paysen, Hendrik; Kosch, Olaf; Trahms, Lutz; Wiekhorst, Frank

2018-05-01

Experimental results are presented demonstrating how temperature can influence the dynamics of magnetic nanoparticles (MNPs) in liquid suspension, when exposed to alternating magnetic fields in the kilohertz frequency range. The measurements used to probe the nanoparticle systems are directly linked to both the emerging biomedical technique of magnetic particle imaging (MPI), and to the recently proposed concept of remote nanoscale thermometry using MNPs under AC field excitation. Here, we report measurements on three common types of MNPs, two of which are currently leading candidates for use as tracers in MPI. Using highly-sensitive magnetic particle spectroscopy (MPS), we demonstrate significant and divergent thermal dependences in several key measures used in the evaluation of MNP dynamics for use in MPI and other applications. The temperature range studied was between 296 and 318 Kelvin, making our findings of particular importance for MPI and other biomedical technologies. Furthermore, we report the detection of the same temperature dependences in measurements conducted using the detection coils within an operational preclinical MPI scanner. This clearly shows the importance of considering temperature during MPI development, and the potential for temperature-resolved MPI using this system. We propose possible physical explanations for the differences in the behaviors observed between the different particle types, and discuss our results in terms of the opportunities and concerns they raise for MPI and other MNP based technologies.

The mechanisms of collinear integration.

PubMed

Cass, John; Alais, David

2006-08-11

Low-contrast visual contour fragments are easier to detect when presented in the context of nearby collinear contour elements (U. Polat & D. Sagi, 1993). The spatial and temporal determinants of this collinear facilitation have been studied extensively (J. R. Cass & B. Spehar, 2005; Y. Tanaka & D. Sagi, 1998; C. B. Williams & R. F. Hess, 1998), although considerable debate surrounds the neural mechanisms underlying it. Our study examines this question using a novel stimulus, whereby the flanking "contour" elements are rotated around their own axis. By measuring contrast detection thresholds to a brief foveal target presented at various phases of flanker rotation, we find peak facilitation after flankers have rotated beyond their collinear phase. This optimal facilitative delay increases monotonically as a function of target-flanker separation, yielding estimates of cortical propagation of 0.1 m/s, a value highly consistent with the dynamics of long-range horizontal interactions observed within primary visual cortex (V1). A curious new finding is also observed: Facilitative peaks also occur when the target flash precedes flanker collinearity by 20-80 ms, a range consistent with contrast-dependent cortical onset latencies. Together, these data suggest that collinear facilitation involves two separate mechanisms, each possessing distinct dynamics: (i) slowly propagating horizontal interactions within V1 and (ii) a faster integrative mechanism, possibly driven by synchronous collinear cortical onset.

Indirectly sensing accelerator beam currents for limiting maximum beam current magnitude

DOEpatents

Bogaty, J.M.; Clifft, B.E.; Bollinger, L.M.

1995-08-08

A beam current limiter is disclosed for sensing and limiting the beam current in a particle accelerator, such as a cyclotron or linear accelerator, used in scientific research and medical treatment. A pair of independently operable capacitive electrodes sense the passage of charged particle bunches to develop an RF signal indicative of the beam current magnitude produced at the output of a bunched beam accelerator. The RF signal produced by each sensing electrode is converted to a variable DC voltage indicative of the beam current magnitude. The variable DC voltages thus developed are compared to each other to verify proper system function and are further compared to known references to detect beam currents in excess of pre-established limits. In the event of a system malfunction, or if the detected beam current exceeds pre-established limits, the beam current limiter automatically inhibits further accelerator operation. A high Q tank circuit associated with each sensing electrode provides a narrow system bandwidth to reduce noise and enhance dynamic range. System linearity is provided by injecting, into each sensing electrode, an RF signal that is offset from the bunching frequency by a pre-determined beat frequency to ensure that subsequent rectifying diodes operate in a linear response region. The system thus provides a large dynamic range in combination with good linearity. 6 figs.

Indirectly sensing accelerator beam currents for limiting maximum beam current magnitude

DOEpatents

Bogaty, John M.; Clifft, Benny E.; Bollinger, Lowell M.

1995-01-01

A beam current limiter for sensing and limiting the beam current in a particle accelerator, such as a cyclotron or linear accelerator, used in scientific research and medical treatment. A pair of independently operable capacitive electrodes sense the passage of charged particle bunches to develop an RF signal indicative of the beam current magnitude produced at the output of a bunched beam accelerator. The RF signal produced by each sensing electrode is converted to a variable DC voltage indicative of the beam current magnitude. The variable DC voltages thus developed are compared to each other to verify proper system function and are further compared to known references to detect beam currents in excess of pre-established limits. In the event of a system malfunction, or if the detected beam current exceeds pre-established limits, the beam current limiter automatically inhibits further accelerator operation. A high Q tank circuit associated with each sensing electrode provides a narrow system bandwidth to reduce noise and enhance dynamic range. System linearity is provided by injecting, into each sensing electrode, an RF signal that is offset from the bunching frequency by a pre-determined beat frequency to ensure that subsequent rectifying diodes operate in a linear response region. The system thus provides a large dynamic range in combination with good linearity.

Data series embedding and scale invariant statistics.

PubMed

Michieli, I; Medved, B; Ristov, S

2010-06-01

Data sequences acquired from bio-systems such as human gait data, heart rate interbeat data, or DNA sequences exhibit complex dynamics that is frequently described by a long-memory or power-law decay of autocorrelation function. One way of characterizing that dynamics is through scale invariant statistics or "fractal-like" behavior. For quantifying scale invariant parameters of physiological signals several methods have been proposed. Among them the most common are detrended fluctuation analysis, sample mean variance analyses, power spectral density analysis, R/S analysis, and recently in the realm of the multifractal approach, wavelet analysis. In this paper it is demonstrated that embedding the time series data in the high-dimensional pseudo-phase space reveals scale invariant statistics in the simple fashion. The procedure is applied on different stride interval data sets from human gait measurements time series (Physio-Bank data library). Results show that introduced mapping adequately separates long-memory from random behavior. Smaller gait data sets were analyzed and scale-free trends for limited scale intervals were successfully detected. The method was verified on artificially produced time series with known scaling behavior and with the varying content of noise. The possibility for the method to falsely detect long-range dependence in the artificially generated short range dependence series was investigated. (c) 2009 Elsevier B.V. All rights reserved.

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

Wilke, R. N., E-mail: rwilke@gwdg.de; Wallentin, J.; Osterhoff, M.

The Large Area Medipix-Based Detector Array (Lambda) has been used in a ptychographic imaging experiment on solar-cell nanowires. By using a semi-transparent central stop, the high flux density provided by nano-focusing Kirkpatrick–Baez mirrors can be fully exploited for high-resolution phase reconstructions. Suitable detection systems that are capable of recording high photon count rates with single-photon detection are instrumental for coherent X-ray imaging. The new single-photon-counting pixel detector ‘Lambda’ has been tested in a ptychographic imaging experiment on solar-cell nanowires using Kirkpatrick–Baez-focused 13.8 keV X-rays. Taking advantage of the high count rate of the Lambda and dynamic range expansion by themore » semi-transparent central stop, a high-dynamic-range diffraction signal covering more than seven orders of magnitude has been recorded, which corresponds to a photon flux density of about 10{sup 5} photons nm{sup −2} s{sup −1} or a flux of ∼10{sup 10} photons s{sup −1} on the sample. By comparison with data taken without the semi-transparent central stop, an increase in resolution by a factor of 3–4 is determined: from about 125 nm to about 38 nm for the nanowire and from about 83 nm to about 21 nm for the illuminating wavefield.« less

Quantitative high dynamic range beam profiling for fluorescence microscopy

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

Mitchell, T. J., E-mail: t.j.mitchell@dur.ac.uk; Saunter, C. D.; O’Nions, W.

2014-10-15

Modern developmental biology relies on optically sectioning fluorescence microscope techniques to produce non-destructive in vivo images of developing specimens at high resolution in three dimensions. As optimal performance of these techniques is reliant on the three-dimensional (3D) intensity profile of the illumination employed, the ability to directly record and analyze these profiles is of great use to the fluorescence microscopist or instrument builder. Though excitation beam profiles can be measured indirectly using a sample of fluorescent beads and recording the emission along the microscope detection path, we demonstrate an alternative approach where a miniature camera sensor is used directly withinmore » the illumination beam. Measurements taken using our approach are solely concerned with the illumination optics as the detection optics are not involved. We present a miniature beam profiling device and high dynamic range flux reconstruction algorithm that together are capable of accurately reproducing quantitative 3D flux maps over a large focal volume. Performance of this beam profiling system is verified within an optical test bench and demonstrated for fluorescence microscopy by profiling the low NA illumination beam of a single plane illumination microscope. The generality and success of this approach showcases a widely flexible beam amplitude diagnostic tool for use within the life sciences.« less

Electromotile hearing: Acoustic tones mask psychophysical response to high-frequency electrical stimulation of intact guinea pig cochleaea)

PubMed Central

Le Prell, Colleen G.; Kawamoto, Kohei; Raphael, Yehoash; Dolan, David F.

2011-01-01

When sinusoidal electric stimulation is applied to the intact cochlea, a frequency-specific acoustic emission can be recorded in the ear canal. Acoustic emissions are produced by basilar membrane motion, and have been used to suggest a corresponding acoustic sensation termed “electromotile hearing.” Electromotile hearing has been specifically attributed to electric stimulation of outer hair cells in the intact organ of Corti. To determine the nature of the auditory perception produced by electric stimulation of a cochlea with intact outer hair cells, we tested guinea pigs in a psychophysical task. First, subjects were trained to report detection of sinusoidal acoustic stimuli and dynamic range was assessed using response latency. Subjects were then implanted with a ball electrode placed into scala tympani. Following the surgical implant procedure, subjects were transferred to a task in which acoustic signals were replaced by sinusoidal electric stimulation, and dynamic range was assessed again. Finally, the ability of acoustic pure-tone stimuli to mask the detection of the electric signals was assessed. Based on the masking effects, we conclude that sinusoidal electric stimulation of the intact cochlea results in perception of a tonal (rather than a broad-band or noisy) sound at a frequency of 8 kHz or above. PMID:17225416

Automated dynamic liquid-liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection for the determination of phenoxy acid herbicides in environmental waters.

PubMed

Wu, Jingming; Ee, Kim Huey; Lee, Hian Kee

2005-08-05

Automated dynamic liquid-liquid-liquid microextraction (D-LLLME) controlled by a programmable syringe pump and combined with HPLC-UV was investigated for the extraction and determination of 5 phenoxy acid herbicides in aqueous samples. In the extraction procedure, the acceptor phase was repeatedly withdrawn into and discharged from the hollow fiber by the syringe pump. The repetitive movement of acceptor phase into and out of the hollow fiber channel facilitated the transfer of analytes into donor phase, from the organic phase held in the pore of the fiber. Parameters such as the organic solvent, concentrations of the donor and acceptor phases, plunger movement pattern, speed of agitation and ionic strength of donor phase were evaluated. Good linearity of analytes was achieved in the range of 0.5-500 ng/ml with coefficients of determination, r2 > 0.9994. Good repeatabilities of extraction performance were obtained with relative standard deviations lower than 7.5%. The method provided up-to 490-fold enrichment within 13 min. In addition, the limits of detection (LODs) ranged from 0.1 to 0.4 ng/mL (S/N = 3). D-LLLME was successfully applied for the analysis of phenoxy acid herbicides from real environmental water samples.

Comparison of three diagnostic methods for the detection of Toxoplasma gondii in free range chickens.

PubMed

Hamidinejat, H; Nabavi, L; Mayahi, M; Ghourbanpoor, M; Pourmehdi Borojeni, M; Norollahi Fard, S; Shokrollahi, M

2014-09-01

Detection of Toxoplasma gondii in free range chickens is an indicator of the prevalence and distribution pattern of T. gondii in the environment. For this purpose, serologic assays especially modified agglutination test (MAT) is the main approach in the literature. The main goal of this study was to compare the polymerase chain reaction (PCR) based on amplification of first internal transcribed spacer (ITS-1) of ribosomal DNA gene, ELISA, and MAT to demonstrate T. gondii infection in free range chicken. A total of 106 adult free - range chickens were killed. Blood, whole heart and brain samples were taken. Sera were examined for the presence of T. gondii antibodies by ELISA and MAT as well. Selected tissues were used for PCR and bioassay in mice. The results revealed that 48.11%, 51.89%, 46.23% and 27.36% of chickens were positive in ELISA, MAT, PCR and bioassay in mice respectively. Good correlation between the results of PCR, ELISA and MAT were detected, but not with bioassay in mice. Compared with PCR, the sensitivity and specificity of ELISA were 92.16% and 96.36% respectively and also for MAT, the sensitivity was 81.81% and the specificity was 92.15%. The specific diagnosis of T. gondii infection in chickens is central to a better understanding of the epidemiology and dynamics of transmission among the various host population and is particularly important for planning effective optimal prevention and control programs. Our data in the present study demonstrated that PCR, ELISA and the MAT are helpful and precise methods to detect T. gondii in naturally infected free-range chickens.

A susceptible-infected model of early detection of respiratory infection outbreaks on a background of influenza

PubMed Central

Mohtashemi, Mojdeh; Szolovits, Peter; Dunyak, James; Mandl, Kenneth D.

2013-01-01

The threat of biological warfare and the emergence of new infectious agents spreading at a global scale have highlighted the need for major enhancements to the public health infrastructure. Early detection of epidemics of infectious diseases requires both real-time data and real-time interpretation of data. Despite moderate advancements in data acquisition, the state of the practice for real-time analysis of data remains inadequate. We present a nonlinear mathematical framework for modeling the transient dynamics of influenza, applied to historical data sets of patients with influenza-like illness. We estimate the vital time-varying epidemiological parameters of infections from historical data, representing normal epidemiological trends. We then introduce simulated outbreaks of different shapes and magnitudes into the historical data, and estimate the parameters representing the infection rates of anomalous deviations from normal trends. Finally, a dynamic threshold-based detection algorithm is devised to assess the timeliness and sensitivity of detecting the irregularities in the data, under a fixed low false-positive rate. We find that the detection algorithm can identify such designated abnormalities in the data with high sensitivity with specificity held at 97%, but more importantly, early during an outbreak. The proposed methodology can be applied to a broad range of influenza-like infectious diseases, whether naturally occurring or a result of bioterrorism, and thus can be an integral component of a real-time surveillance system. PMID:16556450

Ion dynamics of a laser produced aluminium plasma at different ambient pressures

NASA Astrophysics Data System (ADS)

Sankar, Pranitha; Shashikala, H. D.; Philip, Reji

2018-01-01

Plasma is generated by pulsed laser ablation of an Aluminium target using 1064 nm, 7 ns Nd:YAG laser pulses. The spatial and temporal evolution of the whole plasma plume, as well as that of the ionic (Al2+) component present in the plume, are investigated using spectrally resolved time-gated imaging. The influence of ambient gas pressure on the expansion dynamics of Al2+ is studied in particular. In vacuum (10-5 Torr, 10-2 Torr) the whole plume expands adiabatically and diffuses into the ambient. For higher pressures in the range of 1-10 Torr plume expansion is in accordance with the shock wave model, while at 760 Torr the expansion follows the drag model. On the other hand, the expansion dynamics of the Al2+ component, measured by introducing a band pass optical filter in the detection system, fits to the shock wave model for the entire pressure range of 10-2 Torr to 760 Torr. The expansion velocities of the whole plume and the Al2+ component have been measured in vacuum. These dynamics studies are of potential importance for applications such as laser-driven plasma accelerators, ion acceleration, pulsed laser deposition, micromachining, laser-assisted mass spectrometry, ion implantation, and light source generation.

Combinatorial modification of human histone H4 quantitated by two-dimensional liquid chromatography coupled with top down mass spectrometry.

PubMed

Pesavento, James J; Bullock, Courtney R; LeDuc, Richard D; Mizzen, Craig A; Kelleher, Neil L

2008-05-30

Quantitative proteomics has focused heavily on correlating protein abundances, ratios, and dynamics by developing methods that are protein expression-centric (e.g. isotope coded affinity tag, isobaric tag for relative and absolute quantification, etc.). These methods effectively detect changes in protein abundance but fail to provide a comprehensive perspective of the diversity of proteins such as histones, which are regulated by post-translational modifications. Here, we report the characterization of modified forms of HeLa cell histone H4 with a dynamic range >10(4) using a strictly Top Down mass spectrometric approach coupled with two dimensions of liquid chromatography. This enhanced dynamic range enabled the precise characterization and quantitation of 42 forms uniquely modified by combinations of methylation and acetylation, including those with trimethylated Lys-20, monomethylated Arg-3, and the novel dimethylated Arg-3 (each <1% of all H4 forms). Quantitative analyses revealed distinct trends in acetylation site occupancy depending on Lys-20 methylation state. Because both modifications are dynamically regulated through the cell cycle, we simultaneously investigated acetylation and methylation kinetics through three cell cycle phases and used these data to statistically assess the robustness of our quantitative analysis. This work represents the most comprehensive analysis of histone H4 forms present in human cells reported to date.

Development of highly sensitive and selective antibodies for the detection of the explosive pentaerythritol tetranitrate (PETN) by bioisosteric replacement.

PubMed

Hesse, Almut; Biyikal, Mustafa; Rurack, Knut; Weller, Michael G

2016-02-01

An improved antibody against the explosive pentaerythritol tetranitrate (PETN) was developed. The immunogen was designed by the concept of bioisosteric replacement, which led to an excellent polyclonal antibody with extreme selectivity and immunoassays of very good sensitivity. Compounds such as nitroglycerine, 2,4,6-trinitrotoluene, 1,3,5-trinitrobenzene, hexogen (RDX), 2,4,6-trinitroaniline, 1,3-dinitrobenzene, octogen (HMX), triacetone triperoxide, ammonium nitrate, 2,4,6-trinitrophenol and nitrobenzene were tested for potential cross-reactivity. The detection limit of a competitive enzyme-linked immunosorbent assay was determined to be around 0.5 µg/l. The dynamic range of the assay was found to be between 1 and 1000 µg/l, covering a concentration range of three decades. This work shows the successful application of the bioisosteric concept in immunochemistry by exchange of a nitroester to a carbonate diester. The antiserum might be used for the development of quick tests, biosensors, microtitration plate immunoassays, microarrays and other analytical methods for the highly sensitive detection of PETN, an explosive frequently used by terrorists, exploiting the extreme difficulty of its detection. Copyright © 2015 John Wiley & Sons, Ltd.

A cytokine immunosensor for Multiple Sclerosis detection based upon label-free electrochemical impedance spectroscopy using electroplated printed circuit board electrodes.

PubMed

Bhavsar, Kinjal; Fairchild, Aaron; Alonas, Eric; Bishop, Daniel K; La Belle, Jeffrey T; Sweeney, James; Alford, T L; Joshi, Lokesh

2009-10-15

A biosensor for the serum cytokine, Interleukin-12 (IL-12), based upon a label-free electrochemical impedance spectroscopy (EIS) monitoring approach is described. Overexpression of IL-12 has been correlated to the diagnosis of Multiple Sclerosis (MS). An immunosensor has been fabricated by electroplating gold onto a disposable printed circuit board (PCB) electrode and immobilizing anti-IL-12 monoclonal antibodies (MAb) onto the surface of the electrode. This approach yields a robust sensor that facilitates reproducible mass fabrication and easy alteration of the electrode shape. Results indicate that this novel PCB sensor can detect IL-12 at physiological levels, <100 fM with f-values of 0.05 (typically <0.0001) in a label-free and rapid manner. A linear (with respect to log concentration) detectable range was achieved. Detection in a complex biological solution is also explored; however, significant loss of dynamic range is noted in the 100% complex solution. The cost effective approach described here can be used potentially for diagnosis of diseases (like MS) with known biomarkers in body fluids and for monitoring physiological levels of biomolecules with healthcare, food, and environmental relevance.

Detection of piperonal emitted from polymer controlled odor mimic permeation systems utilizing Canis familiaris and solid phase microextraction-ion mobility spectrometry.

PubMed

Macias, Michael S; Guerra-Diaz, Patricia; Almirall, José R; Furton, Kenneth G

2010-02-25

Currently, in the field of odor detection, there is generally a wider variation in limit of detections (LODs) for canines than instruments. The study presented in this paper introduces an improved protocol for the creation of controlled odor mimic permeation system (COMPS) devices for use as standards in canine training and discusses the canine detection thresholds of piperonal, a starting material for the illicit drug 3,4-methylenedioxymethamphetamine (MDMA), when exposed to these devices. Additionally, this paper describes the first-ever reported direct comparison of solid phase microextraction-ion mobility spectrometry (SPME-IMS) to canine detection for the MDMA odorant, piperonal. The research presented shows the reliability of COMPS devices as low cost field calibrants providing a wide range of odorant concentrations for biological and instrumental detectors. The canine LOD of piperonal emanating from the 100 ng s(-1) COMPS was found to be 1 ng as compared to the SPME-IMS LOD of piperonal in a static, closed system at 2 ng, with a linear dynamic range from 2 ng to 11 ng. The utilization of the COMPS devices would allow for training that will reduce the detection variability between canines and maintain improved consistency for training purposes. Since both SPME and IMS are field portable technologies, it is expected that this coupled method will be useful as a complement to canine detection for the field detection of MDMA. 2009 Elsevier Ireland Ltd. All rights reserved.

Acoustic Emission and Echo Signal Compensation Techniques Applied to an Ultrasonic Logging-While-Drilling Caliper.

PubMed

Yao, Yongchao; Ju, Xiaodong; Lu, Junqiang; Men, Baiyong

2017-06-10

A logging-while-drilling (LWD) caliper is a tool used for the real-time measurement of a borehole diameter in oil drilling engineering. This study introduces the mechanical structure and working principle of a new LWD caliper based on ultrasonic distance measurement (UDM). The detection range is a major performance index of a UDM system. This index is determined by the blind zone length and remote reflecting interface detection capability of the system. To reduce the blind zone length and detect near the reflecting interface, a full bridge acoustic emission technique based on bootstrap gate driver (BGD) and metal-oxide-semiconductor field effect transistor (MOSFET) is designed by analyzing the working principle and impedance characteristics of a given piezoelectric transducer. To detect the remote reflecting interface and reduce the dynamic range of the received echo signals, the relationships between the echo amplitude and propagation distance of ultrasonic waves are determined. A signal compensation technique based on time-varying amplification theory, which can automatically change the gain according to the echo arrival time is designed. Lastly, the aforementioned techniques and corresponding circuits are experimentally verified. Results show that the blind zone length in the UDM system of the LWD caliper is significantly reduced and the capability to detect the remote reflecting interface is considerably improved.

Dielectrophoretic label-free immunoassay for rare-analyte quantification in biological samples

NASA Astrophysics Data System (ADS)

Velmanickam, Logeeshan; Laudenbach, Darrin; Nawarathna, Dharmakeerthi

2016-10-01

The current gold standard for detecting or quantifying target analytes from blood samples is the ELISA (enzyme-linked immunosorbent assay). The detection limit of ELISA is about 250 pg/ml. However, to quantify analytes that are related to various stages of tumors including early detection requires detecting well below the current limit of the ELISA test. For example, Interleukin 6 (IL-6) levels of early oral cancer patients are <100 pg/ml and the prostate specific antigen level of the early stage of prostate cancer is about 1 ng/ml. Further, it has been reported that there are significantly less than 1 pg /mL of analytes in the early stage of tumors. Therefore, depending on the tumor type and the stage of the tumors, it is required to quantify various levels of analytes ranging from ng/ml to pg/ml. To accommodate these critical needs in the current diagnosis, there is a need for a technique that has a large dynamic range with an ability to detect extremely low levels of target analytes (

Acoustic Emission and Echo Signal Compensation Techniques Applied to an Ultrasonic Logging-While-Drilling Caliper

PubMed Central

Yao, Yongchao; Ju, Xiaodong; Lu, Junqiang; Men, Baiyong

2017-01-01

A logging-while-drilling (LWD) caliper is a tool used for the real-time measurement of a borehole diameter in oil drilling engineering. This study introduces the mechanical structure and working principle of a new LWD caliper based on ultrasonic distance measurement (UDM). The detection range is a major performance index of a UDM system. This index is determined by the blind zone length and remote reflecting interface detection capability of the system. To reduce the blind zone length and detect near the reflecting interface, a full bridge acoustic emission technique based on bootstrap gate driver (BGD) and metal-oxide-semiconductor field effect transistor (MOSFET) is designed by analyzing the working principle and impedance characteristics of a given piezoelectric transducer. To detect the remote reflecting interface and reduce the dynamic range of the received echo signals, the relationships between the echo amplitude and propagation distance of ultrasonic waves are determined. A signal compensation technique based on time-varying amplification theory, which can automatically change the gain according to the echo arrival time is designed. Lastly, the aforementioned techniques and corresponding circuits are experimentally verified. Results show that the blind zone length in the UDM system of the LWD caliper is significantly reduced and the capability to detect the remote reflecting interface is considerably improved. PMID:28604603

On event-based optical flow detection

PubMed Central

Brosch, Tobias; Tschechne, Stephan; Neumann, Heiko

2015-01-01

Event-based sensing, i.e., the asynchronous detection of luminance changes, promises low-energy, high dynamic range, and sparse sensing. This stands in contrast to whole image frame-wise acquisition by standard cameras. Here, we systematically investigate the implications of event-based sensing in the context of visual motion, or flow, estimation. Starting from a common theoretical foundation, we discuss different principal approaches for optical flow detection ranging from gradient-based methods over plane-fitting to filter based methods and identify strengths and weaknesses of each class. Gradient-based methods for local motion integration are shown to suffer from the sparse encoding in address-event representations (AER). Approaches exploiting the local plane like structure of the event cloud, on the other hand, are shown to be well suited. Within this class, filter based approaches are shown to define a proper detection scheme which can also deal with the problem of representing multiple motions at a single location (motion transparency). A novel biologically inspired efficient motion detector is proposed, analyzed and experimentally validated. Furthermore, a stage of surround normalization is incorporated. Together with the filtering this defines a canonical circuit for motion feature detection. The theoretical analysis shows that such an integrated circuit reduces motion ambiguity in addition to decorrelating the representation of motion related activations. PMID:25941470

A novel amperometric biosensor based on gold nanoparticles anchored on reduced graphene oxide for sensitive detection of l-lactate tumor biomarker.

PubMed

Azzouzi, Sawsen; Rotariu, Lucian; Benito, Ana M; Maser, Wolfgang K; Ben Ali, Mounir; Bala, Camelia

2015-07-15

In this work, a novel amperometric biosensor based on gold nanoparticles anchored on reduced graphene oxide (RGO-AuNPs) and l-lactate dehydrogenase (LDH) was developed for the sensing of l-lactate. Firstly, the RGO-AuNPs modified screen printed electrodes were tested for NADH detection showing a wide dynamic range and a low detection limit. Next, the biosensor was constructed by incorporating both enzyme and RGO-AuNPs in a sol gel matrix derived from tetrametoxysilane and methyltrimetoxysilane. The enzyme loading, working pH, and coenzyme concentration were optimized. The biosensor linearly responded to l-lactate in the range of 10µM-5mM and showed a good specific sensitivity of 154µA/mMcm(2) with a detection limit of 0.13µM. This was accompanied by good reproducibility and operational stability. Tests on artificial serum proved that l-lactate can be determined practically without interferences from commonly interfering compounds such as urate, paracetamol and l-ascorbate. Our LDH/RGO-AuNPs/SPCE based biosensor thus performs as electrochemical device for the detection of l-lactate as a viable early cancer bio-marker. Copyright © 2015 Elsevier B.V. All rights reserved.

Charge dynamics in aluminum oxide thin film studied by ultrafast scanning electron microscopy.

PubMed

Zani, Maurizio; Sala, Vittorio; Irde, Gabriele; Pietralunga, Silvia Maria; Manzoni, Cristian; Cerullo, Giulio; Lanzani, Guglielmo; Tagliaferri, Alberto

2018-04-01

The excitation dynamics of defects in insulators plays a central role in a variety of fields from Electronics and Photonics to Quantum computing. We report here a time-resolved measurement of electron dynamics in 100 nm film of aluminum oxide on silicon by Ultrafast Scanning Electron Microscopy (USEM). In our pump-probe setup, an UV femtosecond laser excitation pulse and a delayed picosecond electron probe pulse are spatially overlapped on the sample, triggering Secondary Electrons (SE) emission to the detector. The zero of the pump-probe delay and the time resolution were determined by measuring the dynamics of laser-induced SE contrast on silicon. We observed fast dynamics with components ranging from tens of picoseconds to few nanoseconds, that fits within the timescales typical of the UV color center evolution. The surface sensitivity of SE detection gives to the USEM the potential of applying pump-probe investigations to charge dynamics at surfaces and interfaces of current nano-devices. The present work demonstrates this approach on large gap insulator surfaces. Copyright © 2018 Elsevier B.V. All rights reserved.

Bennett ion mass spectrometers on the Pioneer Venus Bus and Orbiter

NASA Technical Reports Server (NTRS)

Taylor, H. A., Jr.; Brinton, H. C.; Wagner, T. C. G.; Blackwell, B. H.; Cordier, G. R.

1980-01-01

Identical Bennett radio-frequency ion mass spectrometer instruments on the Pioneer Venus Bus and Orbiter have provided the first in-situ measurements of the detailed composition of the planet's ionosphere. The sensitivity, resolution, and dynamic range are sufficient to provide measurements of the solar-wind-induced bow-shock, the ionopause, and highly structured distributions of up to 16 thermal ion species within the ionosphere. The use of adaptive scan and detection circuits and servo-controlled logic for ion mass and energy analysis permits detection of ion concentrations as low as 5 ions/cu cm and ion flow velocities as large as 9 km/sec for O(+). A variety of commandable modes provides ion sampling rates ranging from 0.1 to 1.6 sec between measurements of a single constituent. A lightweight sensor and electronics housing are features of a compact instrument package.

Label-free functional nucleic acid sensors for detecting target agents

DOEpatents

Lu, Yi; Xiang, Yu

2015-01-13

A general methodology to design label-free fluorescent functional nucleic acid sensors using a vacant site approach and an abasic site approach is described. In one example, a method for designing label-free fluorescent functional nucleic acid sensors (e.g., those that include a DNAzyme, aptamer or aptazyme) that have a tunable dynamic range through the introduction of an abasic site (e.g., dSpacer) or a vacant site into the functional nucleic acids. Also provided is a general method for designing label-free fluorescent aptamer sensors based on the regulation of malachite green (MG) fluorescence. A general method for designing label-free fluorescent catalytic and molecular beacons (CAMBs) is also provided. The methods demonstrated here can be used to design many other label-free fluorescent sensors to detect a wide range of analytes. Sensors and methods of using the disclosed sensors are also provided.

Multi-event waveform-retrieved distributed optical fiber acoustic sensor using dual-pulse heterodyne phase-sensitive OTDR.

PubMed

He, Xiangge; Xie, Shangran; Liu, Fei; Cao, Shan; Gu, Lijuan; Zheng, Xiaoping; Zhang, Min

2017-02-01

We demonstrate a novel type of distributed optical fiber acoustic sensor, with the ability to detect and retrieve actual temporal waveforms of multiple vibration events that occur simultaneously at different positions along the fiber. The system is realized via a dual-pulse phase-sensitive optical time-domain reflectometry, and the actual waveform is retrieved by heterodyne phase demodulation. Experimental results show that the system has a background noise level as low as 8.91×10^-4  rad/√Hz with a demodulation signal-to-noise ratio of 49.17 dB at 1 kHz, and can achieve a dynamic range of ∼60  dB at 1 kHz (0.1 to 104 rad) for phase demodulation, as well as a detection frequency range from 20 Hz to 25 kHz.

Rapid mapping of polarization switching through complete information acquisition

NASA Astrophysics Data System (ADS)

Somnath, Suhas; Belianinov, Alex; Kalinin, Sergei V.; Jesse, Stephen

2016-12-01

Polarization switching in ferroelectric and multiferroic materials underpins a broad range of current and emergent applications, ranging from random access memories to field-effect transistors, and tunnelling devices. Switching in these materials is exquisitely sensitive to local defects and microstructure on the nanometre scale, necessitating spatially resolved high-resolution studies of these phenomena. Classical piezoresponse force microscopy and spectroscopy, although providing necessary spatial resolution, are fundamentally limited in data acquisition rates and energy resolution. This limitation stems from their two-tiered measurement protocol that combines slow (~1 s) switching and fast (~10 kHz-1 MHz) detection waveforms. Here we develop an approach for rapid probing of ferroelectric switching using direct strain detection of material response to probe bias. This approach, facilitated by high-sensitivity electronics and adaptive filtering, enables spectroscopic imaging at a rate 3,504 times faster the current state of the art, achieving high-veracity imaging of polarization dynamics in complex microstructures.

An operating principle of the turtle utricle to detect wide dynamic range.

PubMed

Nam, Jong-Hoon

2018-03-01

The utricle encodes both static information such as head orientation, and dynamic information such as vibrations. It is not well understood how the utricle can encode both static and dynamic information for a wide dynamic range (from <0.05 to >2 times the gravitational acceleration; from DC to > 1000 Hz vibrations). Using computational models of the hair cells in the turtle utricle, this study presents an explanation on how the turtle utricle encodes stimulations over such a wide dynamic range. Two hair bundles were modeled using the finite element method-one representing the striolar hair cell (Cell S), and the other representing the medial extrastriolar hair cell (Cell E). A mechano-transduction (MET) channel model was incorporated to compute MET current (i MET ) due to hair bundle deflection. A macro-mechanical model of the utricle was used to compute otoconial motions from head accelerations (a Head ). According to known anatomical data, Cell E has a long kinocilium that is embedded into the stiff otoconial layer. Unlike Cell E, the hair bundle of Cell S falls short of the otoconial layer. Considering such difference in the mechanical connectivity between the hair cell bundle and the otoconial layer, three cases were simulated: Cell E displacement-clamped, Cell S viscously-coupled, and Cell S displacement-clamped. Head accelerations at different amplitude levels and different frequencies were simulated for the three cases. When a realistic head motion was simulated, Cell E was responsive to head orientation, while the viscously-coupled Cell S was responsive to fast head motion imitating the feeding strike of a turtle. Copyright © 2017 Elsevier B.V. All rights reserved.

Reagent for Evaluating Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Performance in Bottom-Up Proteomic Experiments.

PubMed

Beri, Joshua; Rosenblatt, Michael M; Strauss, Ethan; Urh, Marjeta; Bereman, Michael S

2015-12-01

We present a novel proteomic standard for assessing liquid chromatography-tandem mass spectrometry (LC-MS/MS) instrument performance, in terms of chromatographic reproducibility and dynamic range within a single LC-MS/MS injection. The peptide mixture standard consists of six peptides that were specifically synthesized to cover a wide range of hydrophobicities (grand average hydropathy (GRAVY) scores of -0.6 to 1.9). A combination of stable isotope labeled amino acids ((13)C and (15)N) were inserted to create five isotopologues. By combining these isotopologues at different ratios, they span four orders of magnitude within each distinct peptide sequence. Each peptide, from lightest to heaviest, increases in abundance by a factor of 10. We evaluate several metrics on our quadrupole orbitrap instrument using the 6 × 5 LC-MS/MS reference mixture spiked into a complex lysate background as a function of dynamic range, including mass measurement accuracy (MMA) and the linear range of quantitation of MS1 and parallel reaction monitoring experiments. Detection and linearity of the instrument routinely spanned three orders of magnitude across the gradient (500 fmol to 0.5 fmol on column) and no systematic trend was observed for MMA of targeted peptides as a function of abundance by analysis of variance analysis (p = 0.17). Detection and linearity of the fifth isotopologue (i.e., 0.05 fmol on column) was dependent on the peptide and instrument scan type (MS1 vs PRM). We foresee that this standard will serve as a powerful method to conduct both intra-instrument performance monitoring/evaluation, technology development, and inter-instrument comparisons.

Interplay between Functional Connectivity and Scale-Free Dynamics in Intrinsic fMRI Networks

PubMed Central

Ciuciu, Philippe; Abry, Patrice; He, Biyu J.

2014-01-01

Studies employing functional connectivity-type analyses have established that spontaneous fluctuations in functional magnetic resonance imaging (fMRI) signals are organized within large-scale brain networks. Meanwhile, fMRI signals have been shown to exhibit 1/f-type power spectra – a hallmark of scale-free dynamics. We studied the interplay between functional connectivity and scale-free dynamics in fMRI signals, utilizing the fractal connectivity framework – a multivariate extension of the univariate fractional Gaussian noise model, which relies on a wavelet formulation for robust parameter estimation. We applied this framework to fMRI data acquired from healthy young adults at rest and performing a visual detection task. First, we found that scale-invariance existed beyond univariate dynamics, being present also in bivariate cross-temporal dynamics. Second, we observed that frequencies within the scale-free range do not contribute evenly to inter-regional connectivity, with a systematically stronger contribution of the lowest frequencies, both at rest and during task. Third, in addition to a decrease of the Hurst exponent and inter-regional correlations, task performance modified cross-temporal dynamics, inducing a larger contribution of the highest frequencies within the scale-free range to global correlation. Lastly, we found that across individuals, a weaker task modulation of the frequency contribution to inter-regional connectivity was associated with better task performance manifesting as shorter and less variable reaction times. These findings bring together two related fields that have hitherto been studied separately – resting-state networks and scale-free dynamics, and show that scale-free dynamics of human brain activity manifest in cross-regional interactions as well. PMID:24675649

Polyaniline nanowires-gold nanoparticles hybrid network based chemiresistive hydrogen sulfide sensor

NASA Astrophysics Data System (ADS)

Shirsat, Mahendra D.; Bangar, Mangesh A.; Deshusses, Marc A.; Myung, Nosang V.; Mulchandani, Ashok

2009-02-01

We report a sensitive, selective, and fast responding room temperature chemiresistive sensor for hydrogen sulfide detection and quantification using polyaniline nanowires-gold nanoparticles hybrid network. The sensor was fabricated by facile electrochemical technique. Initially, polyaniline nanowires with a diameter of 250-320 nm bridging the gap between a pair of microfabricated gold electrodes were synthesized using templateless electrochemical polymerization using a two step galvanostatic technique. Polyaniline nanowires were then electrochemically functionalized with gold nanoparticles using cyclic voltammetry technique. These chemiresistive sensors show an excellent limit of detection (0.1 ppb), wide dynamic range (0.1-100 ppb), and very good selectivity and reproducibility.

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

Wu, Chaochao; Duan, Jicheng; Liu, Tao

Human biofluids, especially blood plasma or serum, hold great potential as the sources of candidate biomarkers for various diseases; however, the enormous dynamic range of protein concentrations in biofluids represents a significant analytical challenge for detecting promising low-abundance proteins. Over the last decade, various immunoaffinity chromatographic methods have been developed and routinely applied for separating low-abundance proteins from the high- and moderate-abundance proteins, thus enabling much more effective detection of low-abundance proteins. Herein, we review the advances of immunoaffinity separation methods and their contributions to the proteomic applications in human biofluids. The limitations and future perspectives of immunoaffinity separation methodsmore » are also discussed.« less

Detection of the level of fluoride in the commercially available toothpaste using laser induced breakdown spectroscopy with the marker atomic transition line of neutral fluorine at 731.1 nm

NASA Astrophysics Data System (ADS)

Gondal, M. A.; Maganda, Y. W.; Dastageer, M. A.; Al Adel, F. F.; Naqvi, A. A.; Qahtan, T. F.

2014-04-01

Fourth harmonic of a pulsed Nd:YAG laser (wavelength 266 nm) in combination with high resolution spectrograph equipped with Gated ICCD camera has been employed to design a high sensitive analytical system. This detection system is based on Laser Induced Breakdown Spectroscopy and has been tested first time for analysis of semi-fluid samples to detect fluoride content present in the commercially available toothpaste samples. The experimental parameters were optimized to achieve an optically thin and in local thermo dynamic equilibrium plasma. This improved the limits of detection of fluoride present in tooth paste samples. The strong atomic transition line of fluorine at 731.102 nm was used as the marker line to quantify the fluoride concentration levels. Our LIBS system was able to detect fluoride concentration levels in the range of 1300-1750 ppm with a detection limit of 156 ppm.

The significance of the amorphous potential energy landscape for dictating glassy dynamics and driving solid-state crystallisation.

PubMed

Ruggiero, Michael T; Krynski, Marcin; Kissi, Eric Ofosu; Sibik, Juraj; Markl, Daniel; Tan, Nicholas Y; Arslanov, Denis; van der Zande, Wim; Redlich, Britta; Korter, Timothy M; Grohganz, Holger; Löbmann, Korbinian; Rades, Thomas; Elliott, Stephen R; Zeitler, J Axel

2017-11-15

The fundamental origins surrounding the dynamics of disordered solids near their characteristic glass transitions continue to be fiercely debated, even though a vast number of materials can form amorphous solids, including small-molecule organic, inorganic, covalent, metallic, and even large biological systems. The glass-transition temperature, T g , can be readily detected by a diverse set of techniques, but given that these measurement modalities probe vastly different processes, there has been significant debate regarding the question of why T g can be detected across all of them. Here we show clear experimental and computational evidence in support of a theory that proposes that the shape and structure of the potential-energy surface (PES) is the fundamental factor underlying the glass-transition processes, regardless of the frequency that experimental methods probe. Whilst this has been proposed previously, we demonstrate, using ab initio molecular-dynamics (AIMD) simulations, that it is of critical importance to carefully consider the complete PES - both the intra-molecular and inter-molecular features - in order to fully understand the entire range of atomic-dynamical processes in disordered solids. Finally, we show that it is possible to utilise this dependence to directly manipulate and harness amorphous dynamics in order to control the behaviour of such solids by using high-powered terahertz pulses to induce crystallisation and preferential crystal-polymorph growth in glasses. Combined, these findings provide compelling evidence that the PES landscape, and the corresponding energy barriers, are the ultimate controlling feature behind the atomic and molecular dynamics of disordered solids, regardless of the frequency at which they occur.

Colorimetric method for the detection of melamine using in-situ formed silver nanoparticles via tannic acid

NASA Astrophysics Data System (ADS)

Alam, Md. Fazle; Laskar, Amaj Ahmed; Ahmed, Shahbaz; Shaida, Mohd. Azfar; Younus, Hina

2017-08-01

Melamine toxicity has recently attracted worldwide attention as it causes renal failure and the death of humans and animals. Therefore, developing a simple, fast and sensitive method for the routine detection of melamine is the need of the hour. Herein, we have developed a selective colorimetric method for the detection of melamine in milk samples based upon in-situ formation of silver nanoparticles (AgNPs) via tannic acid. The AgNPs thus formed were characterized by UV-Visible spectrophotometer, transmission electron microscope (TEM), zetasizer and dynamic light scattering (DLS). The AgNPs were used to detect melamine under in vitro condition and in raw milk spiked with melamine. Under optimal conditions, melamine could be selectively detected in vitro within the concentration range of 0.05-1.4 μM with a limit of detection (LOD) of 0.01 μM, which is lower than the strictest melamine safety requirement of 1 ppm. In spiked raw milk, the recovery percentage range was 99.5-106.5% for liquid milk and 98.5-105.5% for powdered milk. The present method shows extreme selectivity with no significant interference with other substances like urea, glucose, glycine, ascorbic acid etc. This assay method does not utilize organic cosolvents, enzymatic reactions, light sensitive dye molecules and sophisticated instrumentation, thereby overcoming some of the limitations of the other conventional methods.

DMS-prefiltered mass spectrometry for the detection of biomarkers

NASA Astrophysics Data System (ADS)

Coy, Stephen L.; Krylov, Evgeny V.; Nazarov, Erkinjon G.

2008-04-01

Technologies based on Differential Mobility Spectrometry (DMS) are ideally matched to rapid, sensitive, and selective detection of chemicals like biomarkers. Biomarkers linked to exposure to radiation, exposure to CWA's, exposure to toxic materials (TICs and TIMs) and to specific diseases are being examined in a number of laboratories. Screening for these types of exposure can be improved in accuracy and greatly speeded up by using DMS-MS instead of slower techniques like LC-MS and GC-MS. We have performed an extensive series of tests with nanospray-DMS-mass spectroscopy and standalone nanospray-DMS obtaining extensive information on chemistry and detectivity. DMS-MS systems implemented with low-resolution, low-cost, portable mass-spectrometry systems are very promising. Lowresolution mass spectrometry alone would be inadequate for the task, but with DMS pre-filtration to suppress interferences, can be quite effective, even for quantitative measurement. Bio-fluids and digests are well suited to ionization by electrospray and detection by mass-spectrometry, but signals from critical markers are overwhelmed by chemical noise from unrelated species, making essential quantitative analysis impossible. Sionex and collaborators have presented data using DMS to suppress chemical noise, allowing detection of cancer biomarkers in 10,000-fold excess of normal products 1,2. In addition, a linear dynamic range of approximately 2,000 has been demonstrated with accurate quantitation 3. We will review the range of possible applications and present new data on DMS-MS biomarker detection.

Nano-biosensor for highly sensitive detection of HER2 positive breast cancer.

PubMed

Salahandish, Razieh; Ghaffarinejad, Ali; Naghib, Seyed Morteza; Majidzadeh-A, Keivan; Zargartalebi, Hossein; Sanati-Nezhad, Amir

2018-05-25

Nanocomposite materials have provided a wide range of conductivity, sensitivity, selectivity and linear response for electrochemical biosensors. However, the detection of rare cells at single cell level requires a new class of nanocomposite-coated electrodes with exceptional sensitivity and specificity. We recently developed a construct of gold nanoparticle-grafted functionalized graphene and nanostructured polyaniline (PANI) for high-performance biosensing within a very wide linear response and selective performance. Further, replacing the expensive gold nanoparticles with low-cost silver nanoparticles as well as optimizing the nanocomposite synthesis and functionalization protocols on the electrode surface in this work enabled us to develop ultrasensitive nanocomposites for label-free detection of breast cancer cells. The sensor presented a fast response time of 30 min within a dynamic range of 10 - 5 × 10 6 cells mL -1 and with a detection limit of 2 cells mL -1 for the detection of SK-BR3 breast cancer cell. The nano-biosensor, for the first time, demonstrated a high efficiency of > 90% for the label-free detection of cancer cells in whole blood sample without any need for sample preparation and cell staining. The results demonstrated that the optimized nanocomposite developed in this work is a promising nanomaterial for electrochemical biosensing and with the potential applications in electro-catalysis and super-capacitances. Copyright © 2018 Elsevier B.V. All rights reserved.

Nonlinear dynamic range transformation in visual communication channels.

PubMed

Alter-Gartenberg, R

1996-01-01

The article evaluates nonlinear dynamic range transformation in the context of the end-to-end continuous-input/discrete processing/continuous-display imaging process. Dynamic range transformation is required when we have the following: (i) the wide dynamic range encountered in nature is compressed into the relatively narrow dynamic range of the display, particularly for spatially varying irradiance (e.g., shadow); (ii) coarse quantization is expanded to the wider dynamic range of the display; and (iii) nonlinear tone scale transformation compensates for the correction in the camera amplifier.

Introduction to State Estimation of High-Rate System Dynamics

PubMed Central

Dodson, Jacob; Joyce, Bryan

2018-01-01

Engineering systems experiencing high-rate dynamic events, including airbags, debris detection, and active blast protection systems, could benefit from real-time observability for enhanced performance. However, the task of high-rate state estimation is challenging, in particular for real-time applications where the rate of the observer’s convergence needs to be in the microsecond range. This paper identifies the challenges of state estimation of high-rate systems and discusses the fundamental characteristics of high-rate systems. A survey of applications and methods for estimators that have the potential to produce accurate estimations for a complex system experiencing highly dynamic events is presented. It is argued that adaptive observers are important to this research. In particular, adaptive data-driven observers are advantageous due to their adaptability and lack of dependence on the system model. PMID:29342855

A dual-waveband dynamic IR scene projector based on DMD

NASA Astrophysics Data System (ADS)

Hu, Yu; Zheng, Ya-wei; Gao, Jiao-bo; Sun, Ke-feng; Li, Jun-na; Zhang, Lei; Zhang, Fang

2016-10-01

Infrared scene simulation system can simulate multifold objects and backgrounds to perform dynamic test and evaluate EO detecting system in the hardware in-the-loop test. The basic structure of a dual-waveband dynamic IR scene projector was introduced in the paper. The system's core device is an IR Digital Micro-mirror Device (DMD) and the radiant source is a mini-type high temperature IR plane black-body. An IR collimation optical system which transmission range includes 3-5μm and 8-12μm is designed as the projection optical system. Scene simulation software was developed with Visual C++ and Vega soft tools and a software flow chart was presented. The parameters and testing results of the system were given, and this system was applied with satisfying performance in an IR imaging simulation testing.

A novel instrumentation circuit for electrochemical measurements.

PubMed

Yin, Li-Te; Wang, Hung-Yu; Lin, Yang-Chiuan; Huang, Wen-Chung

2012-01-01

In this paper, a novel signal processing circuit which can be used for the measurement of H(+) ion and urea concentration is presented. A potentiometric method is used to detect the concentrations of H(+) ions and urea by using H(+) ion-selective electrodes and urea electrodes, respectively. The experimental data shows that this measuring structure has a linear pH response for the concentration range within pH 2 and 12, and the dynamic range for urea concentration measurement is in the range of 0.25 to 64 mg/dL. The designed instrumentation circuit possesses a calibration function and it can be applied to different sensing electrodes for electrochemical analysis. It possesses the advantageous properties of being multi-purpose, easy calibration and low cost.

Laser-ranging long-baseline differential atom interferometers for space

NASA Astrophysics Data System (ADS)

Chiow, Sheng-wey; Williams, Jason; Yu, Nan

2015-12-01

High-sensitivity differential atom interferometers (AIs) are promising for precision measurements in science frontiers in space, including gravity-field mapping for Earth science studies and gravitational wave detection. Difficulties associated with implementing long-baseline differential AIs have previously included the need for a high optical power, large differential Doppler shifts, and narrow dynamic range. We propose a configuration of twin AIs connected by a laser-ranging interferometer (LRI-AI) to provide precise information of the displacements between the two AI reference mirrors and also to phase-lock the two independent interferometer lasers over long distances, thereby drastically improving the practical feasibility of long-baseline differential AI measurements. We show that a properly implemented LRI-AI can achieve equivalent functionality to the conventional differential AI measurement configuration.

Evaluation and analysis of non-intrusive techniques for detecting illicit substances

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

Micklich, B.J.; Roche, C.T.; Fink, C.L.

1995-12-31

Argonne National Laboratory (ANL) and the Houston Advanced Research Center (HARC) have been tasked by the Counterdrug Technology Assessment Center of the Office of National Drug Control Policy to conduct evaluations and analyses of technologies for the non-intrusive inspection of containers for illicit substances. These technologies span the range of nuclear, X-ray, and chemical techniques used in nondestructive sample analysis. ANL has performed assessments of nuclear and X-ray inspection concepts and undertaken site visits with developers to understand the capabilities and the range of applicability of candidate systems. ANL and HARC have provided support to law enforcement agencies (LEAs), includingmore » participation in numerous field studies. Both labs have provided staff to assist in the Narcotics Detection Technology Assessment (NDTA) program for evaluating drug detection systems. Also, the two labs are performing studies of drug contamination of currency. HARC has directed technical evaluations of automated ballistics imaging and identification systems under consideration by law enforcement agencies. ANL and HARC have sponsored workshops and a symposium, and are participating in a Non-Intrusive Inspection Study being led by Dynamics Technology, Incorporated.« less

Determination of penicillamine in pharmaceuticals and human plasma by capillary electrophoresis with in-column fiber optics light-emitting diode induced fluorescence detection.

PubMed

Yang, Xiupei; Yuan, Hongyan; Wang, Chunling; Su, Xiaodong; Hu, Li; Xiao, Dan

2007-10-18

In this paper, a capillary electrophoresis (CE) system with in-column fiber optics light-emitting diode (LED) induced fluorescence detection was developed for the determination of penicillamine (PA). The influence of buffer concentration, buffer pH, applied voltage and injection time was systematically investigated. Optimum separation conditions were obtained with 10 mM borate buffer at pH 9.1, applied voltage 20 kV and 8 s hydrodynamic injection at 30 mbar. The detection system displayed linear dynamic range from 3.2 x 10(-7) to 4.8 x 10(-5) mol L(-1) with a correlation coefficient of 0.9991 and good repeatability (R.S.D.=2.46%). The method was applied to the determination of PA in commercial tablets and human plasma, which the recoveries of standard PA added to tablets and human plasma sample were found to be in the range of 96.26-102.68 and 91.10-99.35%, respectively. The proposed method is cheap, rapid, easy, and accurate, and can be successfully applied to the formulation analysis and bioanalysis.

Dark field imaging system for size characterization of magnetic micromarkers

NASA Astrophysics Data System (ADS)

Malec, A.; Haiden, C.; Kokkinis, G.; Keplinger, F.; Giouroudi, I.

2017-05-01

In this paper we demonstrate a dark field video imaging system for the detection and size characterization of individual magnetic micromarkers suspended in liquid and the detection of pathogens utilizing magnetically labelled E.coli. The system follows dynamic processes and interactions of moving micro/nano objects close to or below the optical resolution limit, and is especially suitable for small sample volumes ( 10 μl). The developed detection method can be used to obtain clinical information about liquid contents when an additional biological protocol is provided, i.e., binding of microorganisms (e.g. E.coli) to specific magnetic markers. Some of the major advantages of our method are the increased sizing precision in the micro- and nano-range as well as the setup's simplicity making it a perfect candidate for miniaturized devices. Measurements can thus be carried out in a quick, inexpensive, and compact manner. A minor limitation is that the concentration range of micromarkers in a liquid sample needs to be adjusted in such a manner that the number of individual particles in the microscope's field of view is sufficient.

A Very Large Array search for emission from HI associated with nearby Lyman alpha absorbers

NASA Technical Reports Server (NTRS)

Van Gorkom, J. H.; Bahcall, J. N.; Jannuzi, B. T.; Schneider, D. P.

1993-01-01

We present a sensitive Very Large Array (VLA) search for H I emission from the vicinity of the Lyman alpha clouds in the Virgo Cluster, which were recently discovered with Hubble Space Telescope (HST) in absorption toward the nearest quasar 3C273. We searched an area of 40 by 40 arcmin centered on 3C273, covering a velocity range from 840 to 1840 km/s. The bandpass was self-calibrated on 3C273 leading to a spectral dynamic range of better than 10(exp 5) to 1. No H I was detected. The rms noise in the final images corresponds to a 3 sigma column density sensitivity of 2.8 x 10(exp 19) sq cm on scales of a few kpc. Small H I clouds could have been detected down to a few times 10(exp 6) solar mass. Our failure to detect H I emission at the higher column densities sets a lower limit to the radius of the Lyman alpha clouds of 3.9 kpc, assuming a spherical geometry.

Evaluation of detector dynamic range in the x-ray exposure domain in mammography: a comparison between film-screen and flat panel detector systems.

PubMed

Cooper, Virgil N; Oshiro, Thomas; Cagnon, Christopher H; Bassett, Lawrence W; McLeod-Stockmann, Tyler M; Bezrukiy, Nikita V

2003-10-01

Digital detectors in mammography have wide dynamic range in addition to the benefit of decoupled acquisition and display. How wide the dynamic range is and how it compares to film-screen systems in the clinical x-ray exposure domain are unclear. In this work, we compare the effective dynamic ranges of film-screen and flat panel mammography systems, along with the dynamic ranges of their component image receptors in the clinical x-ray exposure domain. An ACR mammography phantom was imaged using variable mAs (exposure) values for both systems. The dynamic range of the contrast-limited film-screen system was defined as that ratio of mAs (exposure) values for a 26 kVp Mo/Mo (HVL=0.34 mm Al) beam that yielded passing phantom scores. The same approach was done for the noise-limited digital system. Data from three independent observers delineated a useful phantom background optical density range of 1.27 to 2.63, which corresponded to a dynamic range of 2.3 +/- 0.53. The digital system had a dynamic range of 9.9 +/- 1.8, which was wider than the film-screen system (p<0.02). The dynamic range of the film-screen system was limited by the dynamic range of the film. The digital detector, on the other hand, had an estimated dynamic range of 42, which was wider than the dynamic range of the digital system in its entirety by a factor of 4. The generator/tube combination was the limiting factor in determining the digital system's dynamic range.

High sensitive and direct fluorescence detection of single viral DNA sequences by integration of double strand probes onto microgels particles.

PubMed

Aliberti, A; Cusano, A M; Battista, E; Causa, F; Netti, P A

2016-02-21

A novel class of probes for fluorescence detection was developed and combined to microgel particles for a high sensitive fluorescence detection of nucleic acids. A double strand probe with an optimized fluorescent-quencher couple was designed for the detection of different lengths of nucleic acids (39 nt and 100 nt). Such probe proved efficient in target detection in different contests and specific even in presence of serum proteins. The conjugation of double strand probes onto polymeric microgels allows for a sensitive detection of DNA sequences from HIV, HCV and SARS corona viruses with a LOD of 1.4 fM, 3.7 fM and 1.4 fM, respectively, and with a dynamic range of 10(-9)-10(-15) M. Such combination enhances the sensitivity of the detection of almost five orders of magnitude when compared to the only probe. The proposed platform based on the integration of innovative double strand probe into microgels particles represents an attractive alternative to conventional sensitive DNA detection technologies that rely on amplifications methods.

Detecting the Influence of Spreading in Social Networks with Excitable Sensor Networks

PubMed Central

Pei, Sen; Tang, Shaoting; Zheng, Zhiming

2015-01-01

Detecting spreading outbreaks in social networks with sensors is of great significance in applications. Inspired by the formation mechanism of humans’ physical sensations to external stimuli, we propose a new method to detect the influence of spreading by constructing excitable sensor networks. Exploiting the amplifying effect of excitable sensor networks, our method can better detect small-scale spreading processes. At the same time, it can also distinguish large-scale diffusion instances due to the self-inhibition effect of excitable elements. Through simulations of diverse spreading dynamics on typical real-world social networks (Facebook, coauthor, and email social networks), we find that the excitable sensor networks are capable of detecting and ranking spreading processes in a much wider range of influence than other commonly used sensor placement methods, such as random, targeted, acquaintance and distance strategies. In addition, we validate the efficacy of our method with diffusion data from a real-world online social system, Twitter. We find that our method can detect more spreading topics in practice. Our approach provides a new direction in spreading detection and should be useful for designing effective detection methods. PMID:25950181

Applications of high-frequency radar

NASA Astrophysics Data System (ADS)

Headrick, J. M.; Thomason, J. F.

1998-07-01

Efforts to extend radar range by an order of magnitude with use of the ionosphere as a virtual mirror started after the end of World War II. A number of HF radar programs were pursued, with long-range nuclear burst and missile launch detection demonstrated by 1956. Successful east coast radar aircraft detect and track tests extending across the Atlantic were conducted by 1961. The major obstacles to success, the large target-to-clutter ratio and low signal-to-noise ratio, were overcome with matched filter Doppler processing. To search the areas that a 2000 nautical mile (3700 km) radar can reach, very complex and high dynamic range processing is required. The spectacular advances in digital processing technology have made truly wide-area surveillance possible. Use of the surface attached wave over the oceans can enable HF radar to obtain modest extension of range beyond the horizon. The decameter wavelengths used by both skywave and surface wave radars require large physical antenna apertures, but they have unique capabilities for air and surface targets, many of which are of resonant scattering dimensions. Resonant scattering from the ocean permits sea state and direction estimation. Military and commercial applications of HF radar are in their infancy.

Calcium-dependent molecular fMRI using a magnetic nanosensor.

PubMed

Okada, Satoshi; Bartelle, Benjamin B; Li, Nan; Breton-Provencher, Vincent; Lee, Jiyoung J; Rodriguez, Elisenda; Melican, James; Sur, Mriganka; Jasanoff, Alan

2018-06-01

Calcium ions are ubiquitous signalling molecules in all multicellular organisms, where they mediate diverse aspects of intracellular and extracellular communication over widely varying temporal and spatial scales 1 . Though techniques to map calcium-related activity at a high resolution by optical means are well established, there is currently no reliable method to measure calcium dynamics over large volumes in intact tissue 2 . Here, we address this need by introducing a family of magnetic calcium-responsive nanoparticles (MaCaReNas) that can be detected by magnetic resonance imaging (MRI). MaCaReNas respond within seconds to [Ca 2+ ] changes in the 0.1-1.0 mM range, suitable for monitoring extracellular calcium signalling processes in the brain. We show that the probes permit the repeated detection of brain activation in response to diverse stimuli in vivo. MaCaReNas thus provide a tool for calcium-activity mapping in deep tissue and offer a precedent for the development of further nanoparticle-based sensors for dynamic molecular imaging with MRI.

Imaging electric field dynamics with graphene optoelectronics

DOE PAGES

Horng, Jason; Balch, Halleh B.; McGuire, Allister F.; ...

2016-12-16

The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts,more » a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena.« less

Comparison of candidate solar array maximum power utilization approaches. [for spacecraft propulsion

NASA Technical Reports Server (NTRS)

Costogue, E. N.; Lindena, S.

1976-01-01

A study was made of five potential approaches that can be utilized to detect the maximum power point of a solar array while sustaining operations at or near maximum power and without endangering stability or causing array voltage collapse. The approaches studied included: (1) dynamic impedance comparator, (2) reference array measurement, (3) onset of solar array voltage collapse detection, (4) parallel tracker, and (5) direct measurement. The study analyzed the feasibility and adaptability of these approaches to a future solar electric propulsion (SEP) mission, and, specifically, to a comet rendezvous mission. Such missions presented the most challenging requirements to a spacecraft power subsystem in terms of power management over large solar intensity ranges of 1.0 to 3.5 AU. The dynamic impedance approach was found to have the highest figure of merit, and the reference array approach followed closely behind. The results are applicable to terrestrial solar power systems as well as to other than SEP space missions.

Protein-Fragment Complementation Assays for Large-Scale Analysis, Functional Dissection, and Spatiotemporal Dynamic Studies of Protein-Protein Interactions in Living Cells.

PubMed

Michnick, Stephen W; Landry, Christian R; Levy, Emmanuel D; Diss, Guillaume; Ear, Po Hien; Kowarzyk, Jacqueline; Malleshaiah, Mohan K; Messier, Vincent; Tchekanda, Emmanuelle

2016-11-01

Protein-fragment complementation assays (PCAs) comprise a family of assays that can be used to study protein-protein interactions (PPIs), conformation changes, and protein complex dimensions. We developed PCAs to provide simple and direct methods for the study of PPIs in any living cell, subcellular compartments or membranes, multicellular organisms, or in vitro. Because they are complete assays, requiring no cell-specific components other than reporter fragments, they can be applied in any context. PCAs provide a general strategy for the detection of proteins expressed at endogenous levels within appropriate subcellular compartments and with normal posttranslational modifications, in virtually any cell type or organism under any conditions. Here we introduce a number of applications of PCAs in budding yeast, Saccharomyces cerevisiae These applications represent the full range of PPI characteristics that might be studied, from simple detection on a large scale to visualization of spatiotemporal dynamics. © 2016 Cold Spring Harbor Laboratory Press.

Imaging electric field dynamics with graphene optoelectronics

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

Horng, Jason; Balch, Halleh B.; McGuire, Allister F.

The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts,more » a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena.« less

Calcium-dependent molecular fMRI using a magnetic nanosensor

NASA Astrophysics Data System (ADS)

Okada, Satoshi; Bartelle, Benjamin B.; Li, Nan; Breton-Provencher, Vincent; Lee, Jiyoung J.; Rodriguez, Elisenda; Melican, James; Sur, Mriganka; Jasanoff, Alan

2018-06-01

Calcium ions are ubiquitous signalling molecules in all multicellular organisms, where they mediate diverse aspects of intracellular and extracellular communication over widely varying temporal and spatial scales1. Though techniques to map calcium-related activity at a high resolution by optical means are well established, there is currently no reliable method to measure calcium dynamics over large volumes in intact tissue2. Here, we address this need by introducing a family of magnetic calcium-responsive nanoparticles (MaCaReNas) that can be detected by magnetic resonance imaging (MRI). MaCaReNas respond within seconds to [Ca2+] changes in the 0.1-1.0 mM range, suitable for monitoring extracellular calcium signalling processes in the brain. We show that the probes permit the repeated detection of brain activation in response to diverse stimuli in vivo. MaCaReNas thus provide a tool for calcium-activity mapping in deep tissue and offer a precedent for the development of further nanoparticle-based sensors for dynamic molecular imaging with MRI.

Co-occurrence dynamics of endangered Lower Keys marsh rabbits and free-ranging domestic cats: Prey responses to an exotic predator removal program.

PubMed

Cove, Michael V; Gardner, Beth; Simons, Theodore R; O'Connell, Allan F

2018-04-01

The Lower Keys marsh rabbit ( Sylvilagus palustris hefneri ) is one of many endangered endemic species of the Florida Keys. The main threats are habitat loss and fragmentation from sea-level rise, development, and habitat succession. Exotic predators such as free-ranging domestic cats ( Felis catus ) pose an additional threat to these endangered small mammals. Management strategies have focused on habitat restoration and exotic predator control. However, the effectiveness of predator removal and the effects of anthropogenic habitat modifications and restoration have not been evaluated. Between 2013 and 2015, we used camera traps to survey marsh rabbits and free-ranging cats at 84 sites in the National Key Deer Refuge, Big Pine Key, Florida, USA. We used dynamic occupancy models to determine factors associated with marsh rabbit occurrence, colonization, extinction, and the co-occurrence of marsh rabbits and cats during a period of predator removal. Rabbit occurrence was positively related to freshwater habitat and patch size, but was negatively related to the number of individual cats detected at each site. Furthermore, marsh rabbit colonization was negatively associated with relative increases in the number of individual cats at each site between survey years. Cat occurrence was negatively associated with increasing distance from human developments. The probability of cat site extinction was positively related to a 2-year trapping effort, indicating that predator removal reduced the cat population. Dynamic co-occurrence models suggested that cats and marsh rabbits co-occur less frequently than expected under random conditions, whereas co-detections were site and survey-specific. Rabbit site extinction and colonization were not strongly conditional on cat presence, but corresponded with a negative association. Our results suggest that while rabbits can colonize and persist at sites where cats occur, it is the number of individual cats at a site that more strongly influences rabbit occupancy and colonization. These findings indicate that continued predator management would likely benefit endangered small mammals as they recolonize restored habitats.

Linearized electrooptic polymeric directional coupler modulator

NASA Astrophysics Data System (ADS)

Hung, Yu-Chueh

External linearized modulators are required in high-performance analog optical communication systems since the performance of conventional modulators, such as Mach-Zehnder modulators, are degraded by distortions by the nonlinearity of their transfer functions. Various linearization schemes have been proposed to increase the dynamic range of an analog optical link. Most of the optical schemes involve multiple Mach-Zehnder modulators, either in parallel or series configuration, incorporated with strict balance of RF and bias control. This is a significant challenge when it comes to practical implementation. In this dissertation, a linearized two-section directional coupler modulator made from electrooptic polymer is presented. The coupling coefficient of each section is tailored by properly tuning the refractive index contrast, which can be easily employed using the photobleaching technique in polymer technology. A two-tone test was performed to evaluate the linearity of the modulator and the spur-free dynamic range shows a 7.5 dB improvement compared to a conventional Mach-Zehnder modulator. This scheme avoids multiple modulators or complicated modulation synchronization and demonstrates a compact design in real implementation. Most of the linearization schemes up to date consider only the direct detection mode of operation. However, the RF output characteristics at the detection side are determined differently by various system parameters if a coherent link is implemented instead. Therefore, different considerations of linearization have to be examined for this kind of application. In the second part of this dissertation, the impact of various modulation scenarios on the system performance of an analog coherent optical link will be addressed. It will be shown that a directional coupler modulator is better suited at increasing the dynamic range in coherent optical links. Specific designs of a directional coupler modulator shows an SFDR improvement of 20 dB compared to a Mach-Zehnder modulator. This new type of device can be easily fabricated using photobleaching technique in eletrooptic polymer and can be utilized in various applications.

Detection and Characterization of Low Temperature Peat Fires during the 2015 Fire Catastrophe in Indonesia Using a New High-Sensitivity Fire Monitoring Satellite Sensor (FireBird)

PubMed Central

Atwood, Elizabeth C.; Englhart, Sandra; Lorenz, Eckehard; Halle, Winfried; Wiedemann, Werner; Siegert, Florian

2016-01-01

Vast and disastrous fires occurred on Borneo during the 2015 dry season, pushing Indonesia into the top five carbon emitting countries. The region was affected by a very strong El Niño-Southern Oscillation (ENSO) climate phenomenon, on par with the last severe event in 1997/98. Fire dynamics in Central Kalimantan were investigated using an innovative sensor offering higher sensitivity to a wider range of fire intensities at a finer spatial resolution (160 m) than heretofore available. The sensor is onboard the TET-1 satellite, part of the German Aerospace Center (DLR) FireBird mission. TET-1 images (acquired every 2–3 days) from the middle infrared were used to detect fires continuously burning for almost three weeks in the protected peatlands of Sebangau National Park as well as surrounding areas with active logging and oil palm concessions. TET-1 detection capabilities were compared with MODIS active fire detection and Landsat burned area algorithms. Fire dynamics, including fire front propagation speed and area burned, were investigated. We show that TET-1 has improved detection capabilities over MODIS in monitoring low-intensity peatland fire fronts through thick smoke and haze. Analysis of fire dynamics revealed that the largest burned areas resulted from fire front lines started from multiple locations, and the highest propagation speeds were in excess of 500 m/day (all over peat > 2m deep). Fires were found to occur most often in concessions that contained drainage infrastructure but were not cleared prior to the fire season. Benefits of implementing this sensor system to improve current fire management techniques are discussed. Near real-time fire detection together with enhanced fire behavior monitoring capabilities would not only improve firefighting efforts, but also benefit analysis of fire impact on tropical peatlands, greenhouse gas emission estimations as well as mitigation measures to reduce severe fire events in the future. PMID:27486664

Detection and Characterization of Low Temperature Peat Fires during the 2015 Fire Catastrophe in Indonesia Using a New High-Sensitivity Fire Monitoring Satellite Sensor (FireBird).

PubMed

Atwood, Elizabeth C; Englhart, Sandra; Lorenz, Eckehard; Halle, Winfried; Wiedemann, Werner; Siegert, Florian

2016-01-01

Vast and disastrous fires occurred on Borneo during the 2015 dry season, pushing Indonesia into the top five carbon emitting countries. The region was affected by a very strong El Niño-Southern Oscillation (ENSO) climate phenomenon, on par with the last severe event in 1997/98. Fire dynamics in Central Kalimantan were investigated using an innovative sensor offering higher sensitivity to a wider range of fire intensities at a finer spatial resolution (160 m) than heretofore available. The sensor is onboard the TET-1 satellite, part of the German Aerospace Center (DLR) FireBird mission. TET-1 images (acquired every 2-3 days) from the middle infrared were used to detect fires continuously burning for almost three weeks in the protected peatlands of Sebangau National Park as well as surrounding areas with active logging and oil palm concessions. TET-1 detection capabilities were compared with MODIS active fire detection and Landsat burned area algorithms. Fire dynamics, including fire front propagation speed and area burned, were investigated. We show that TET-1 has improved detection capabilities over MODIS in monitoring low-intensity peatland fire fronts through thick smoke and haze. Analysis of fire dynamics revealed that the largest burned areas resulted from fire front lines started from multiple locations, and the highest propagation speeds were in excess of 500 m/day (all over peat > 2m deep). Fires were found to occur most often in concessions that contained drainage infrastructure but were not cleared prior to the fire season. Benefits of implementing this sensor system to improve current fire management techniques are discussed. Near real-time fire detection together with enhanced fire behavior monitoring capabilities would not only improve firefighting efforts, but also benefit analysis of fire impact on tropical peatlands, greenhouse gas emission estimations as well as mitigation measures to reduce severe fire events in the future.

Observation of nonlinear dissipation in piezoresistive diamond nanomechanical resonators by heterodyne down-mixing.

PubMed

Imboden, Matthias; Williams, Oliver A; Mohanty, Pritiraj

2013-09-11

We report the observation of nonlinear dissipation in diamond nanomechanical resonators measured by an ultrasensitive heterodyne down-mixing piezoresistive detection technique. The combination of a hybrid structure as well as symmetry breaking clamps enables sensitive piezoresistive detection of multiple orthogonal modes in a diamond resonator over a wide frequency and temperature range. Using this detection method, we observe the transition from purely linear dissipation at room temperature to strongly nonlinear dissipation at cryogenic temperatures. At high drive powers and below liquid nitrogen temperatures, the resonant structure dynamics follows the Pol-Duffing equation of motion. Instead of using the broadening of the full width at half-maximum, we propose a nonlinear dissipation backbone curve as a method to characterize the strength of nonlinear dissipation in devices with a nonlinear spring constant.

Absolute charge calibration of scintillating screens for relativistic electron detection

NASA Astrophysics Data System (ADS)

Buck, A.; Zeil, K.; Popp, A.; Schmid, K.; Jochmann, A.; Kraft, S. D.; Hidding, B.; Kudyakov, T.; Sears, C. M. S.; Veisz, L.; Karsch, S.; Pawelke, J.; Sauerbrey, R.; Cowan, T.; Krausz, F.; Schramm, U.

2010-03-01

We report on new charge calibrations and linearity tests with high-dynamic range for eight different scintillating screens typically used for the detection of relativistic electrons from laser-plasma based acceleration schemes. The absolute charge calibration was done with picosecond electron bunches at the ELBE linear accelerator in Dresden. The lower detection limit in our setup for the most sensitive scintillating screen (KODAK Biomax MS) was 10 fC/mm2. The screens showed a linear photon-to-charge dependency over several orders of magnitude. An onset of saturation effects starting around 10-100 pC/mm2 was found for some of the screens. Additionally, a constant light source was employed as a luminosity reference to simplify the transfer of a one-time absolute calibration to different experimental setups.

CO2 detection using polyethylenimine/starch functionalized AlGaN /GaN high electron mobility transistors

NASA Astrophysics Data System (ADS)

Chang, C. Y.; Kang, B. S.; Wang, H. T.; Ren, F.; Wang, Y. L.; Pearton, S. J.; Dennis, D. M.; Johnson, J. W.; Rajagopal, P.; Roberts, J. C.; Piner, E. L.; Linthicum, K. J.

2008-06-01

AlGaN /GaN high electron mobility transistors (HEMTs) functionalized with polyethylenimine/starch were used for detecting CO2 with a wide dynamic range of 0.9%-50% balanced with nitrogen at temperatures from 46to220°C. Higher detection sensitivity to CO2 gas was achieved at higher testing temperatures. At a fixed source-drain bias voltage of 0.5V, drain-source current of the functionalized HEMTs showed a sublinear correlation upon exposure to different CO2 concentrations at low temperature. The superlinear relationship was at high temperature. The sensor exhibited a reversible behavior and a repeatable current change of 32 and 47μA with the introduction of 28.57% and 37.5% CO2 at 108°C, respectively.

Molecular dynamics simulations of dislocations in TlBr crystals under an electrical field

DOE PAGES

Zhou, X. W.; Foster, M. E.; Yang, P.; ...

2016-07-13

TlBr crystals have superior radiation detection properties; however, their properties degrade in the range of hours to weeks when an operating electrical field is applied. To account for this rapid degradation using the widely-accepted vacancy migration mechanism, the vacancy concentration must be orders of magnitude higher than any conventional estimates. The present work has incorporated a new analytical variable charge model in molecular dynamics (MD) simulations to examine the structural changes of materials under electrical fields. Our simulations indicate that dislocations in TlBr move under electrical fields. As a result, this discovery can lead to new understanding of TlBr agingmore » mechanisms under external fields.« less

Photoionization Modeling

NASA Technical Reports Server (NTRS)

Kallman, T.

2010-01-01

Warm absorber spectra are characterized by the many lines from partially ionized intermediate-Z elements, and iron, detected with the grating instruments on Chandra and XMM-Newton. If these ions are formed in a gas which is in photoionization equilibrium, they correspond to a broad range of ionization parameters, although there is evidence for certain preferred values. A test for any dynamical model for these outflows is to reproduce these properties, at some level of detail. In this paper we present a statistical analysis of the ionization distribution which can be applied both the observed spectra and to theoretical models. As an example, we apply it to our dynamical models for warm absorber outflows, based on evaporation from the molecular torus.

Land-based lidar mapping: a new surveying technique to shed light on rapid topographic change

USGS Publications Warehouse

Collins, Brian D.; Kayen, Robert

2006-01-01

The rate of natural change in such dynamic environments as rivers and coastlines can sometimes overwhelm the monitoring capacity of conventional surveying methods. In response to this limitation, U.S. Geological Survey (USGS) scientists are pioneering new applications of light detection and ranging (lidar), a laser-based scanning technology that promises to greatly increase our ability to track rapid topographic changes and manage their impact on affected communities.

Influence Of Momentum Excess On The Pattern And Dynamics Of Intermediate-Range Stratified Wakes

DTIC Science & Technology

2016-06-01

excess in order to model the fundamental differences between signatures generated by towed and self- propelled bodies in various ocean states. In cases...which can be used on the operational level for developing and improving algorithms for non- acoustic signature prediction and detection. 14. SUBJECT...order to model the fundamental differences between signatures generated by towed and self- propelled bodies in various ocean states. In cases where

Enhanced weak-signal sensitivity in two-photon microscopy by adaptive illumination.

PubMed

Chu, Kengyeh K; Lim, Daryl; Mertz, Jerome

2007-10-01

We describe a technique to enhance both the weak-signal relative sensitivity and the dynamic range of a laser scanning optical microscope. The technique is based on maintaining a fixed detection power by fast feedback control of the illumination power, thereby transferring high measurement resolution to weak signals while virtually eliminating the possibility of image saturation. We analyze and demonstrate the benefits of adaptive illumination in two-photon fluorescence microscopy.

Multifrequency high precise subTHz-THz-IR spectroscopy for exhaled breath research

NASA Astrophysics Data System (ADS)

Vaks, Vladimir L.; Domracheva, Elena G.; Pripolzin, Sergey I.; Chernyaeva, Mariya B.

2016-09-01

Nowadays the development of analytical spectroscopy with high performance, sensitivity and spectral resolution for exhaled breath research is attended. The method of two-frequency high precise THz spectroscopy and the method of high precise subTHz-THz-IR spectroscopy are presented. Development of a subTHz-THz-IR gas analyzer increases the number of gases that can be identified and the reliability of the detection by confirming the signature in both THz and MIR ranges. The testing measurements have testified this new direction of analytical spectroscopy to open widespread trends of its using for various problems of medicine and biology. First of all, there are laboratory investigations of the processes in exhaled breath and studying of their dynamics. Besides, the methods presented can be applied for detecting intermediate and short time living products of reactions in exhaled breath. The spectrometers have been employed for investigations of acetone, methanol and ethanol in the breath samples of healthy volunteers and diabetes patients. The results have demonstrated an increased concentration of acetone in breath of diabetes patients. The dynamic of changing the acetone concentration before and after taking the medicines is discovered. The potential markers of pre-cancer states and oncological diseases of gastrointestinal tract organs have been detected. The changes in the NO concentration in exhaled breath of cancer patients during radiotherapy as well as increase of the NH3 concentration at gastrointestinal diseases have been revealed. The preliminary investigations of biomarkers in three frequency ranges have demonstrated the advantages of the multifrequency high precise spectroscopy for noninvasive medical diagnostics.

Capillary electromigration separation of proteins and microorganisms dynamically modified by chromophoric nonionogenic surfactant.

PubMed

Horká, Marie; Růzicka, Filip; Holá, Veronika; Kahle, Vladislav; Moravcová, Dana; Slais, Karel

2009-08-15

A chromophoric nonionogenic surfactant poly(ethylene glycol) 3-(2-hydroxy-5-n-octylphenylazo)-benzoate, HOPAB, has been prepared and used as a buffer additive for a dynamic modification of proteins and/or microorganisms including Escherichia coli , Staphylococcus epidermidis (biofilm-positive and biofilm-negative), and the strains of yeast cells Candida albicans and Candida parapsilosis (biofilm-positive and biofilm-negative) during a capillary electrophoresis and a capillary isoelectric focusing (CIEF) with UV detection at 326 nm. Values of isoelectric points of labeled proteins and microorganisms have been calculated using UV-detectable pI markers and have been found comparable with pI of the native compounds. Minimum detectable amount has been assessed lower than picograms of proteins and lower than a hundred cells injected into a separation capillary. The introduced labeling method facilitates CIEF separation of microorganisms from the clinical sample of the infected urine at their clinically important levels in the pH gradient pH range of 2-5 and their subsequent cultivation. At the same time, it has enabled the determination of albumin in human urine as a major clinical marker of urinary tract infections and kidney diseases.

Direct sampling of chemical weapons in water by photoionization mass spectrometry.

PubMed

Syage, Jack A; Cai, Sheng-Suan; Li, Jianwei; Evans, Matthew D

2006-05-01

The vulnerability of water supplies to toxic contamination calls for fast and effective means for screening water samples for multiple threats. We describe the use of photoionization (PI) mass spectrometry (MS) for high-speed, high-throughput screening and molecular identification of chemical weapons (CW) threats and other hazardous compounds. The screening technology can detect a wide range of compounds at subacute concentrations with no sample preparation and a sampling cycle time of approximately 45 s. The technology was tested with CW agents VX, GA, GB, GD, GF, HD, HN1, and HN3, in addition to riot agents and precursors. All are sensitively detected and give simple PI mass spectra dominated by the parent ion. The target application of the PI MS method is as a routine, real-time early warning system for CW agents and other hazardous compounds in air and in water. In this work, we also present comprehensive measurements for water analysis and report on the system detection limits, linearity, quantitation accuracy, and false positive (FP) and false negative rates for concentrations at subacute levels. The latter data are presented in the form of receiver operating characteristic curves of the form of detection probability P(D) versus FP probability P(FP). These measurements were made using the CW surrogate compounds, DMMP, DEMP, DEEP, and DIMP. Method detection limits (3sigma) obtained using a capillary injection method yielded 1, 6, 3, and 2 ng/mL, respectively. These results were obtained using 1-microL injections of water samples without any preparation, corresponding to mass detection limits of 1, 6, 3, and 2 pg, respectively. The linear range was about 3-4 decades and the dynamic range about 4-5 decades. The relative standard deviations were generally <10% at CW subacute concentrations levels.

Microfluidic-integrated patterned ITO immunosensor for rapid detection of prostate-specific membrane antigen biomarker in prostate cancer.

PubMed

Seenivasan, Rajesh; Singh, Chandra K; Warrick, Jay W; Ahmad, Nihal; Gunasekaran, Sundaram

2017-09-15

An optically transparent patterned indium tin oxide (ITO) three-electrode sensor integrated with a microfluidic channel was designed for label-free immunosensing of prostate-specific membrane antigen (PSMA), a prostate cancer (PCa) biomarker, expressed on prostate tissue and circulating tumor cells but also found in serum. The sensor relies on cysteamine capped gold nanoparticles (N-AuNPs) covalently linked with anti-PSMA antibody (Ab) for target specificity. A polydimethylsiloxane (PDMS) microfluidic channel is used to efficiently and reproducibly introduce sample containing soluble proteins/cells to the sensor. The PSMA is detected and quantified by measuring the change in differential pulse voltammetry signal of a redox probe ([Fe(CN) 6 ] 3- /[Fe(CN) 6 ] 4- ) that is altered upon binding of PSMA with PSMA-Ab immobilized on N-AuNPs/ITO. Detection of PSMA expressing cells and soluble PSMA was tested. The limit of detection (LOD) of the sensor for PSMA-based PCa cells is 6/40µL (i.e., 150 cells/mL) (n=3) with a linear range of 15-400 cells/40µL (i.e., 375-10,000 cells/mL), and for the soluble PSMA is 0.499ng/40µL (i.e., 12.5ng/mL) (n=3) with the linear range of 0.75-250ng/40µL (i.e., 19-6250ng/mL), both with an incubation time of 10min. The results indicate that the sensor has a suitable sensitivity and dynamic range for routine detection of PCa circulating tumor cells and can be adapted to detect other biomarkers/cancer cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of three new condensation particle counters for sub-3 nm particle detection during the Helsinki CPC workshop: the ADI versatile water CPC, TSI 3777 nano enhancer and boosted TSI 3010

NASA Astrophysics Data System (ADS)

Kangasluoma, Juha; Hering, Susanne; Picard, David; Lewis, Gregory; Enroth, Joonas; Korhonen, Frans; Kulmala, Markku; Sellegri, Karine; Attoui, Michel; Petäjä, Tuukka

2017-06-01

In this study we characterized the performance of three new particle counters able to detect particles smaller than 3 nm during the Helsinki condensation particle counter (CPC) workshop in summer 2016: the Aerosol Dynamics Inc. (ADI; Berkeley, USA) versatile water condensation particle counter (vWCPC), TSI 3777 nano enhancer (TSI Inc., Shoreview, USA) and modified and boosted TSI 3010-type CPC from Université Blaise Pascal called a B3010. The performance of all CPCs was first measured with charged tungsten oxide test particles at temperature settings which resulted in supersaturation low enough to not detect any ions produced by a radioactive source. Due to similar measured detection efficiencies, additional comparison between the 3777 and vWCPC were conducted using electrically neutral tungsten oxide test particles and with positively charged tetradodecylammonium bromide. Furthermore, the detection efficiencies of the 3777 and vWCPC were measured with boosted temperature settings yielding supersaturation which was at the onset of homogeneous nucleation for the 3777 or confined within the range of liquid water for the ADI vWCPC. Finally, CPC-specific tests were conducted to probe the response of the 3777 to various inlet flow relative humidities, of the B3010 to various inlet flow rates and of the vWCPC to various particle concentrations. For the 3777 and vWCPC the measured 50 % detection diameters (d50s) were in the range of 1.3-2.4 nm for the tungsten oxide particles, depending on the particle charging state and CPC temperature settings, between 2.5 and 3.3 nm for the organic test aerosol, and in the range of 3.2-3.4 nm for tungsten oxide for the B3010.

Magnetic detection of mercuric ion using giant magnetoresistance-based biosensing system.

PubMed

Wang, Wei; Wang, Yi; Tu, Liang; Klein, Todd; Feng, Yinglong; Li, Qin; Wang, Jian-Ping

2014-04-15

We have demonstrated a novel sensing strategy employing a giant magnetoresistance (GMR) biosensor and DNA chemistry for the detection of mercuric ion (Hg(2+)). This assay takes advantages of high sensitivity and real-time signal readout of GMR biosensor and high selectivity of thymine-thymine (T-T) pair for Hg(2+). The assay has a detection limit of 10 nM in both buffer and natural water, which is the maximum mercury level in drinking water regulated by U.S. Environmental Protection Agency (EPA). The magnitude of the dynamic range for Hg(2+) detection is up to three orders (10 nM to 10 μM). Herein, GMR sensing technology is first introduced into a pollutant monitoring area. It can be foreseen that the GMR biosensor could become a robust contender in the areas of environmental monitoring and food safety testing.

Subranging scheme for SQUID sensors

NASA Technical Reports Server (NTRS)

Penanen, Konstantin I. (Inventor)

2008-01-01

A readout scheme for measuring the output from a SQUID-based sensor-array using an improved subranging architecture that includes multiple resolution channels (such as a coarse resolution channel and a fine resolution channel). The scheme employs a flux sensing circuit with a sensing coil connected in series to multiple input coils, each input coil being coupled to a corresponding SQUID detection circuit having a high-resolution SQUID device with independent linearizing feedback. A two-resolution configuration (course and fine) is illustrated with a primary SQUID detection circuit for generating a fine readout, and a secondary SQUID detection circuit for generating a course readout, both having feedback current coupled to the respective SQUID devices via feedback/modulation coils. The primary and secondary SQUID detection circuits function and derive independent feedback. Thus, the SQUID devices may be monitored independently of each other (and read simultaneously) to dramatically increase slew rates and dynamic range.

Optofluidic analysis system for amplification-free, direct detection of Ebola infection

NASA Astrophysics Data System (ADS)

Cai, H.; Parks, J. W.; Wall, T. A.; Stott, M. A.; Stambaugh, A.; Alfson, K.; Griffiths, A.; Mathies, R. A.; Carrion, R.; Patterson, J. L.; Hawkins, A. R.; Schmidt, H.

2015-09-01

The massive outbreak of highly lethal Ebola hemorrhagic fever in West Africa illustrates the urgent need for diagnostic instruments that can identify and quantify infections rapidly, accurately, and with low complexity. Here, we report on-chip sample preparation, amplification-free detection and quantification of Ebola virus on clinical samples using hybrid optofluidic integration. Sample preparation and target preconcentration are implemented on a PDMS-based microfluidic chip (automaton), followed by single nucleic acid fluorescence detection in liquid-core optical waveguides on a silicon chip in under ten minutes. We demonstrate excellent specificity, a limit of detection of 0.2 pfu/mL and a dynamic range of thirteen orders of magnitude, far outperforming other amplification-free methods. This chip-scale approach and reduced complexity compared to gold standard RT-PCR methods is ideal for portable instruments that can provide immediate diagnosis and continued monitoring of infectious diseases at the point-of-care.

Development of an Electrochemical Immunosensor for Fumonisins Detection in Foods

PubMed Central

Kadir, Mohamad Kamal Abdul; Tothill, Ibtisam E.

2010-01-01

An electrochemical affinity sensor for the determination of fumonisins mycotoxins (Fms) using monoclonal antibody modified screen-printed gold electrode with carbon counter and silver-silver chloride pseudo-reference electrode is reported in this work. A direct competitive enzyme-linked immunosorbent assay (ELISA) was initially developed, exhibiting a detection limit of 100 µg·L-1 for fumonisins. This was then transferred to the surface of a bare gold screen-printed electrode (SPGE) and detection was performed by chronoamperometry, monitoring the reaction of 3,3’,5,5’-Tetramethylbenzidine dihydrochloride (TMB) and hydrogen peroxide (H2O2) catalysed by HRP at −100 mV potential vs. onboard Ag-AgCl pseudo-reference electrode. The immunosensor exhibited detection limit of 5 µg·L−1 fumonisins with a dynamic range from 1 µg·L−1–1000 µg·L−1. The sensor also performed well in extracted corn samples. PMID:22069591

An electrochemical immunosensor for quantitative detection of ficolin-3

NASA Astrophysics Data System (ADS)

San, Lili; Zeng, Dongdong; Song, Shiping; Zuo, Xiaolei; Zhang, Huan; Wang, Chenguang; Wu, Jiarui; Mi, Xianqiang

2016-06-01

Diabetes mellitus (DM) is one of the most common metabolic disorders in the world, of which more than 90% is type-2 diabetes mellitus (T2DM). There is a rather urgent need for reliable, sensitive and quick detection techniques in clinical application of T2DM. Ficolin-3 is a potential biomarker of T2DM, because serum ficolin-3 levels are associated with insulin resistance and predict the incidence of T2DM. Herein, a sandwich-type electrochemical immunosensor was developed for the detection of ficolin-3 in human serum. Cyclic voltammetry and the amperometric current versus time were used to characterize the performance of the immunosensor. Under optimal conditions, the detection limitation of ficolin-3 was 100 ng ml-1 and the linear dynamic range was between 2 and 50 μg ml-1. The method has ideal accuracy, excellent stability and selectivity and has wide application prospects in clinical research.

Autonomous microfluidic system for phosphate detection.

PubMed

McGraw, Christina M; Stitzel, Shannon E; Cleary, John; Slater, Conor; Diamond, Dermot

2007-02-28

Miniaturization of analytical devices through the advent of microfluidics and micro total analysis systems is an important step forward for applications such as medical diagnostics and environmental monitoring. The development of field-deployable instruments requires that the entire system, including all necessary peripheral components, be miniaturized and packaged in a portable device. A sensor for long-term monitoring of phosphate levels has been developed that incorporates sampling, reagent and waste storage, detection, and wireless communication into a complete, miniaturized system. The device employs a low-power detection and communication system, so the entire instrument can operate autonomously for 7 days on a single rechargeable, 12V battery. In addition, integration of a wireless communication device allows the instrument to be controlled and results to be downloaded remotely. This autonomous system has a limit of detection of 0.3mg/L and a linear dynamic range between 0 and 20mg/L.

Visual detection of glial cell line-derived neurotrophic factor based on a molecular translator and isothermal strand-displacement polymerization reaction.

PubMed

Zhang, Li-Yong; Xing, Tao; Du, Li-Xin; Li, Qing-Min; Liu, Wei-Dong; Wang, Ji-Yue; Cai, Jing

2015-01-01

Glial cell line-derived neurotrophic factor (GDNF) is a small protein that potently promotes the survival of many types of neurons. Detection of GDNF is vital to monitoring the survival of sympathetic and sensory neurons. However, the specific method for GDNF detection is also un-discovered. The purpose of this study is to explore the method for protein detection of GDNF. A novel visual detection method based on a molecular translator and isothermal strand-displacement polymerization reaction (ISDPR) has been proposed for the detection of GDNF. In this study, a molecular translator was employed to convert the input protein to output deoxyribonucleic acid signal, which was further amplified by ISDPR. The product of ISDPR was detected by a lateral flow biosensor within 30 minutes. This novel visual detection method based on a molecular translator and ISDPR has very high sensitivity and selectivity, with a dynamic response ranging from 1 pg/mL to 10 ng/mL, and the detection limit was 1 pg/mL of GDNF. This novel visual detection method exhibits high sensitivity and selectivity, which is very simple and universal for GDNF detection to help disease therapy in clinical practice.

Detecting Interplanetary Dust Particles with Radars to Study the Dynamics at the Edge of the Space

NASA Technical Reports Server (NTRS)

Janches, Diego

2015-01-01

The Earth's mesosphere is the region of the atmosphere between approximately 60-120 km altitude, where the transition from hydrodynamic flow to molecular diffusion occurs. It is highly dynamic region where turbulence by wave braking is produced and energy is deposited from sources from both, below and above this altitude range. Because aircraft and nearly all balloons reach altitudes below approximately 50 km and orbital spacecrafts are well above approximately 400 km, the mesosphere has only been accessed through the use of sounding rockets or remote sensing techniques, and as a result, it is the most poorly understood part of the atmosphere. In addition, millions of Interplanetary Dust Particles (IDPs) enter the atmosphere. Within the mesosphere most of these IDPs melt or vaporize as a result of collisions with the air particles producing meteors that can be detected with radars. This provides a mean to study the dynamics of this region. In this lecture the basic principles of the utilization of meteor radars to study the dynamics of the mesosphere will be presented. A system overview of these systems will be provided as well as discuss the advantages/disadvantages of these systems, provide details of the data processing methodology and give a brief overview of the current status of the field as well as the vision for the next decade.

Electrochemical force microscopy

DOEpatents

Kalinin, Sergei V.; Jesse, Stephen; Collins, Liam F.; Rodriguez, Brian J.

2017-01-10

A system and method for electrochemical force microscopy are provided. The system and method are based on a multidimensional detection scheme that is sensitive to forces experienced by a biased electrode in a solution. The multidimensional approach allows separation of fast processes, such as double layer charging, and charge relaxation, and slow processes, such as diffusion and faradaic reactions, as well as capturing the bias dependence of the response. The time-resolved and bias measurements can also allow probing both linear (small bias range) and non-linear (large bias range) electrochemical regimes and potentially the de-convolution of charge dynamics and diffusion processes from steric effects and electrochemical reactivity.

Transient dynamics of invasive competition: barred owls, spotted owls, habitat, and the demons of competition present.

PubMed

Dugger, Katie M; Anthony, Robert G; Andrews, Lawrence S

2011-10-01

The recent range expansion of Barred Owls (Strix varia) into the Pacific Northwest, where the species now co-occurs with the endemic Northern Spotted Owl (Strix occidentalis caurina), resulted in a unique opportunity to investigate potential competition between two congeneric, previously allopatric species. The primary criticism of early competition research was the use of current species' distribution patterns to infer past processes; however, the recent expansion of the Barred Owl and the ability to model the processes that result in site occupancy (i.e., colonization and extinction) allowed us to address the competitive process directly rather than inferring past processes through current patterns. The purpose of our study was to determine whether Barred Owls had any negative effects on occupancy dynamics of nesting territories by Northern Spotted Owls and how these effects were influenced by habitat characteristics of Spotted Owl territories. We used single-species, multi-season occupancy models and covariates quantifying Barred Owl detections and habitat characteristics to model extinction and colonization rates of Spotted Owl pairs in southern Oregon, USA. We observed a strong, negative association between Barred Owl detections and colonization rates and a strong positive effect of Barred Owl detections on extinction rates of Spotted Owls. We observed increased extinction rates in response to decreased amounts of old forest at the territory core and higher colonization rates when old-forest habitat was less fragmented. Annual site occupancy for pairs reflected the strong effects of Barred Owls on occupancy dynamics with much lower occupancy rates predicted for territories where Barred Owls were detected. The strong Barred Owl and habitat effects on occupancy dynamics of Spotted Owls provided evidence of interference competition between the species. These effects increase the importance of conserving large amounts of contiguous, old-forest habitat to maintain Northern Spotted Owls in the landscape.

Dynamic range in the C. elegans brain network

NASA Astrophysics Data System (ADS)

Antonopoulos, Chris G.

2016-01-01

We study external electrical perturbations and their responses in the brain dynamic network of the Caenorhabditis elegans soil worm, given by the connectome of its large somatic nervous system. Our analysis is inspired by a realistic experiment where one stimulates externally specific parts of the brain and studies the persistent neural activity triggered in other cortical regions. In this work, we perturb groups of neurons that form communities, identified by the walktrap community detection method, by trains of stereotypical electrical Poissonian impulses and study the propagation of neural activity to other communities by measuring the corresponding dynamic ranges and Steven law exponents. We show that when one perturbs specific communities, keeping the rest unperturbed, the external stimulations are able to propagate to some of them but not to all. There are also perturbations that do not trigger any response. We found that this depends on the initially perturbed community. Finally, we relate our findings for the former cases with low neural synchronization, self-criticality, and large information flow capacity, and interpret them as the ability of the brain network to respond to external perturbations when it works at criticality and its information flow capacity becomes maximal.

Microwave soft x-ray microscopy for nanoscale magnetization dynamics in the 5–10 GHz frequency range

DOE PAGES

Bonetti, Stefano; Kukreja, Roopali; Chen, Zhao; ...

2015-09-10

In this study, we present a scanning transmission x-ray microscopy setup combined with a novel microwave synchronization scheme in order to study high frequency magnetization dynamics at synchrotron light sources. The sensitivity necessary to detect small changes of the magnetization on short time scales and nanometer spatial dimensions is achieved by combination of the developed excitation mechanism with a single photon counting electronics that is locked to the synchrotron operation frequency. The required mechanical stability is achieved by a compact design of the microscope. Our instrument is capable of creating direct images of dynamical phenomena in the 5-10 GHz range,more » with 35 nm resolution. When used together with circularly polarized x-rays, the above capabilities can be combined to study magnetic phenomena at microwave frequencies, such as ferromagnetic resonance (FMR) and spin waves. We demonstrate the capabilities of our technique by presenting phase resolved images of a –6 GHz nanoscale spin wave generated by a spin torque oscillator, as well as the uniform ferromagnetic precession with ~0.1° amplitude at –9 GHz in a micrometer-sized cobalt strip.« less

Sensitivity to microstimulation of somatosensory cortex distributed over multiple electrodes.

PubMed

Kim, Sungshin; Callier, Thierri; Tabot, Gregg A; Tenore, Francesco V; Bensmaia, Sliman J

2015-01-01

Meaningful and repeatable tactile sensations can be evoked by electrically stimulating primary somatosensory cortex. Intracortical microstimulation (ICMS) may thus be a viable approach to restore the sense of touch in individuals who have lost it, for example tetraplegic patients. One of the potential limitations of this approach, however, is that high levels of current can damage the neuronal tissue if the resulting current densities are too high. The limited range of safe ICMS amplitudes thus limits the dynamic range of ICMS-evoked sensations. One way to get around this limitation would be to distribute the ICMS over multiple electrodes in the hopes of intensifying the resulting percept without increasing the current density experienced by the neuronal tissue. Here, we test whether stimulating through multiple electrodes is a viable solution to increase the dynamic range of ICMS-elicited sensations without increasing the peak current density. To this end, we compare the ability of non-human primates to detect ICMS delivered through one vs. multiple electrodes. We also compare their ability to discriminate pulse trains differing in amplitude when these are delivered through one or more electrodes. We find that increasing the number of electrodes through which ICMS is delivered only has a marginal effect on detectability or discriminability despite the fact that 2-4 times more current is delivered overall. Furthermore, the impact of multielectrode stimulation (or lack thereof) is found whether pulses are delivered synchronously or asynchronously, whether the leading phase of the pulses is cathodic or anodic, and regardless of the spatial configuration of the electrode groups.

Rate and timing cues associated with the cochlear amplifier: level discrimination based on monaural cross-frequency coincidence detection.

PubMed

Heinz, M G; Colburn, H S; Carney, L H

2001-10-01

The perceptual significance of the cochlear amplifier was evaluated by predicting level-discrimination performance based on stochastic auditory-nerve (AN) activity. Performance was calculated for three models of processing: the optimal all-information processor (based on discharge times), the optimal rate-place processor (based on discharge counts), and a monaural coincidence-based processor that uses a non-optimal combination of rate and temporal information. An analytical AN model included compressive magnitude and level-dependent-phase responses associated with the cochlear amplifier, and high-, medium-, and low-spontaneous-rate (SR) fibers with characteristic frequencies (CFs) spanning the AN population. The relative contributions of nonlinear magnitude and nonlinear phase responses to level encoding were compared by using four versions of the model, which included and excluded the nonlinear gain and phase responses in all possible combinations. Nonlinear basilar-membrane (BM) phase responses are robustly encoded in near-CF AN fibers at low frequencies. Strongly compressive BM responses at high frequencies near CF interact with the high thresholds of low-SR AN fibers to produce large dynamic ranges. Coincidence performance based on a narrow range of AN CFs was robust across a wide dynamic range at both low and high frequencies, and matched human performance levels. Coincidence performance based on all CFs demonstrated the "near-miss" to Weber's law at low frequencies and the high-frequency "mid-level bump." Monaural coincidence detection is a physiologically realistic mechanism that is extremely general in that it can utilize AN information (average-rate, synchrony, and nonlinear-phase cues) from all SR groups.

Long term monitoring of jaguars in the Cockscomb Basin Wildlife Sanctuary, Belize; Implications for camera trap studies of carnivores

PubMed Central

Harmsen, Bart J.; Foster, Rebecca J.; Sanchez, Emma; Gutierrez-González, Carmina E.; Silver, Scott C.; Ostro, Linde E. T.; Kelly, Marcella J.; Kay, Elma; Quigley, Howard

2017-01-01

In this study, we estimate life history parameters and abundance for a protected jaguar population using camera-trap data from a 14-year monitoring program (2002–2015) in Belize, Central America. We investigated the dynamics of this jaguar population using 3,075 detection events of 105 individual adult jaguars. Using robust design open population models, we estimated apparent survival and temporary emigration and investigated individual heterogeneity in detection rates across years. Survival probability was high and constant among the years for both sexes (φ = 0.78), and the maximum (conservative) age recorded was 14 years. Temporary emigration rate for the population was random, but constant through time at 0.20 per year. Detection probability varied between sexes, and among years and individuals. Heterogeneity in detection took the form of a dichotomy for males: those with consistently high detection rates, and those with low, sporadic detection rates, suggesting a relatively stable population of ‘residents’ consistently present and a fluctuating layer of ‘transients’. Female detection was always low and sporadic. On average, twice as many males than females were detected per survey, and individual detection rates were significantly higher for males. We attribute sex-based differences in detection to biases resulting from social variation in trail-walking behaviour. The number of individual females detected increased when the survey period was extended from 3 months to a full year. Due to the low detection rates of females and the variable ‘transient’ male subpopulation, annual abundance estimates based on 3-month surveys had low precision. To estimate survival and monitor population changes in elusive, wide-ranging, low-density species, we recommend repeated surveys over multiple years; and suggest that continuous monitoring over multiple years yields even further insight into population dynamics of elusive predator populations. PMID:28658274

Targeted Data Extraction of the MS/MS Spectra Generated by Data-independent Acquisition: A New Concept for Consistent and Accurate Proteome Analysis*

PubMed Central

Gillet, Ludovic C.; Navarro, Pedro; Tate, Stephen; Röst, Hannes; Selevsek, Nathalie; Reiter, Lukas; Bonner, Ron; Aebersold, Ruedi

2012-01-01

Most proteomic studies use liquid chromatography coupled to tandem mass spectrometry to identify and quantify the peptides generated by the proteolysis of a biological sample. However, with the current methods it remains challenging to rapidly, consistently, reproducibly, accurately, and sensitively detect and quantify large fractions of proteomes across multiple samples. Here we present a new strategy that systematically queries sample sets for the presence and quantity of essentially any protein of interest. It consists of using the information available in fragment ion spectral libraries to mine the complete fragment ion maps generated using a data-independent acquisition method. For this study, the data were acquired on a fast, high resolution quadrupole-quadrupole time-of-flight (TOF) instrument by repeatedly cycling through 32 consecutive 25-Da precursor isolation windows (swaths). This SWATH MS acquisition setup generates, in a single sample injection, time-resolved fragment ion spectra for all the analytes detectable within the 400–1200 m/z precursor range and the user-defined retention time window. We show that suitable combinations of fragment ions extracted from these data sets are sufficiently specific to confidently identify query peptides over a dynamic range of 4 orders of magnitude, even if the precursors of the queried peptides are not detectable in the survey scans. We also show that queried peptides are quantified with a consistency and accuracy comparable with that of selected reaction monitoring, the gold standard proteomic quantification method. Moreover, targeted data extraction enables ad libitum quantification refinement and dynamic extension of protein probing by iterative re-mining of the once-and-forever acquired data sets. This combination of unbiased, broad range precursor ion fragmentation and targeted data extraction alleviates most constraints of present proteomic methods and should be equally applicable to the comprehensive analysis of other classes of analytes, beyond proteomics. PMID:22261725

Space vehicle approach velocity judgments under simulated visual space conditions

NASA Technical Reports Server (NTRS)

Haines, R. F.

1989-01-01

There were 35 volunteers who responded when they first perceived an increase in apparent size of a collimated, two-dimensional perspective image of an Orbiter vehicle. The variables of interest included the presence (or absence) of a fixed reticle within the field of view (FOV), background starfield velocity, initial range to the vehicle and vehicle closure velocity. It was found that: 1) increasing vehicle approach velocity yielded a very small (but significant) effect of faster detection of vehicle movement, nevertheless, response variability was relatively large; 2) including the fixed reticle in the FOV produced significantly slower detection of vehicle radial movement, however this occurred only at the largest range and the magnitude of the effect was only about 15% of the one sigma value; and 3) increasing background star velocity during this judgment led to slower detection of vehicle movement. While statistically significant, this effect was small and occurred primarily at the largest range. A possible explanation for the last two findings is that other static and dynamic objects within the visual field may compete for available attention which otherwise would be available for judging image expansion; thus, the target's retinal image has to expand more than otherwise for its movement to be detected. This study also showed that the Proximity Operations Research Mockup at NASA/Ames can be used effectively to investigate a variety of visual judgment questions related to future space operations. These findings are discussed in relation to previous research and possible underlying mechanisms.

A nanocomposite optosensor containing carboxylic functionalized multiwall carbon nanotubes and quantum dots incorporated into a molecularly imprinted polymer for highly selective and sensitive detection of ciprofloxacin.

PubMed

Yuphintharakun, Naphat; Nurerk, Piyaluk; Chullasat, Kochaporn; Kanatharana, Proespichaya; Davis, Frank; Sooksawat, Dhassida; Bunkoed, Opas

2018-08-05

A nanocomposite optosensor consisting of carboxylic acid functionalized multiwall carbon nanotubes and CdTe quantum dots embedded inside a molecularly imprinted polymer (COOH@MWCNT-MIP-QDs) was developed for trace ciprofloxacin detection. The COOH@MWCNT-MIP-QDs were synthesized through a facile sol-gel process using ciprofloxacin as a template molecule, 3-aminopropylethoxysilane as a functional monomer and tetraethoxysilane as a cross-linker at a molar ratio of 1:8:20. The synthesized nanocomposite optosensor had high sensitivity, excellent specificity and high binding affinity to ciprofloxacin. Under optimal conditions, the fluorescence intensity of the optosensor decreased in a linear fashion with the concentration of ciprofloxacin and two linear dynamic ranges were obtained, 0.10-1.0 μg L -1 and 1.0-100.0 μg L -1 with a very low limit of detection of 0.066 μg L -1 . The imprinting factors of the two linear range were 17.67 and 4.28, respectively. The developed nanocomposite fluorescence probe was applied towards the determination of ciprofloxacin levels in chicken muscle and milk samples with satisfactory recoveries being obtained in the range of 82.6 to 98.4%. The results were also in good agreement with a HPLC method which indicates that the optosensor can be used as a sensitive, selective and rapid method to detect ciprofloxacin in chicken and milk samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Using a high spatial resolution tactile sensor for intention detection.

PubMed

Castellini, Claudio; Koiva, Risto

2013-06-01

Intention detection is the interpretation of biological signals with the aim of automatically, reliably and naturally understanding what a human subject desires to do. Although intention detection is not restricted to disabled people, such methods can be crucial in improving a patient's life, e.g., aiding control of a robotic wheelchair or of a self-powered prosthesis. Traditionally, intention detection is done using, e.g., gaze tracking, surface electromyography and electroencephalography. In this paper we present exciting initial results of an experiment aimed at intention detection using a high-spatial-resolution, high-dynamic-range tactile sensor. The tactile image of the ventral side of the forearm of 9 able-bodied participants was recorded during a variable-force task stimulated at the fingertip. Both the forces at the fingertip and at the forearm were synchronously recorded. We show that a standard dimensionality reduction technique (Principal Component Analysis) plus a Support Vector Machine attain almost perfect detection accuracy of the direction and the intensity of the intended force. This paves the way for high spatial resolution tactile sensors to be used as a means for intention detection.

Dynamical behavior of a single polymer chain under nanometric confinement

NASA Astrophysics Data System (ADS)

Lagrené, K.; Zanotti, J.-M.; Daoud, M.; Farago, B.; Judeinstein, P.

2010-10-01

We address the dynamical behavior of a single polymer chain under nanometric confinement. We consider a polymer melt made of a mixture of hydrogenated and deuterated high molecular mass Poly(Ethylene Oxide) (PEO). The confining material is a membrane of Anodic Aluminum Oxide (AAO), a macroscopically highly ordered confining system made of parallel cylindrical channels. We use Neutron Spin-Echo (NSE) under the Zero Average Contrast (ZAC) condition to, all at once, i) match the intense porous AAO detrimental elastic SANS (Small Angle Neutron Scattering) contribution to the total intermediate scattering function I(Q,t) and ii) measure the Q dependence of the dynamical modes of a single chain under confinement. The polymer dynamics is probed on an extremely broad spacial ([2.2 10-2 Å-1, 0.2 Å-1]) and temporal ([0.1 ns, 600 ns]) ranges. We do not detect any influence of confinement on the polymer dynamics. This result is discussed in the framework of the debate on the existence of a "corset effect" recently suggested by NMR relaxometry data.

Collective Dynamics and Strong Pinning near the Onset of Charge Order in La1.48Nd0.4Sr0.12CuO4

NASA Astrophysics Data System (ADS)

Baity, P. G.; Sasagawa, T.; Popović, Dragana

2018-04-01

The dynamics of charge-ordered states is one of the key issues in underdoped cuprate high-temperature superconductors, but static short-range charge-order (CO) domains have been detected in almost all cuprates. We probe the dynamics across the CO (and structural) transition in La1.48Nd0.4Sr0.12CuO4 by measuring nonequilibrium charge transport, or resistance R as the system responds to a change in temperature and to an applied magnetic field. We find evidence for metastable states, collective behavior, and criticality. The collective dynamics in the critical regime indicates strong pinning by disorder. Surprisingly, nonequilibrium effects, such as avalanches in R , are revealed only when the critical region is approached from the charge-ordered phase. Our results on La1.48Nd0.4Sr0.12CuO4 provide the long-sought evidence for the fluctuating order across the CO transition, and also set important constraints on theories of dynamic stripes.

Dynamic Singularity Spectrum Distribution of Sea Clutter

NASA Astrophysics Data System (ADS)

Xiong, Gang; Yu, Wenxian; Zhang, Shuning

2015-12-01

The fractal and multifractal theory have provided new approaches for radar signal processing and target-detecting under the background of ocean. However, the related research mainly focuses on fractal dimension or multifractal spectrum (MFS) of sea clutter. In this paper, a new dynamic singularity analysis method of sea clutter using MFS distribution is developed, based on moving detrending analysis (DMA-MFSD). Theoretically, we introduce the time information by using cyclic auto-correlation of sea clutter. For transient correlation series, the instantaneous singularity spectrum based on multifractal detrending moving analysis (MF-DMA) algorithm is calculated, and the dynamic singularity spectrum distribution of sea clutter is acquired. In addition, we analyze the time-varying singularity exponent ranges and maximum position function in DMA-MFSD of sea clutter. For the real sea clutter data, we analyze the dynamic singularity spectrum distribution of real sea clutter in level III sea state, and conclude that the radar sea clutter has the non-stationary and time-varying scale characteristic and represents the time-varying singularity spectrum distribution based on the proposed DMA-MFSD method. The DMA-MFSD will also provide reference for nonlinear dynamics and multifractal signal processing.

A Novel Detection Platform for Shrimp White Spot Syndrome Virus Using an ICP11-Dependent Immunomagnetic Reduction (IMR) Assay.

PubMed

Liu, Bing-Hsien; Lin, Yu-Chen; Ho, Chia-Shin; Yang, Che-Chuan; Chang, Yun-Tsui; Chang, Jui-Feng; Li, Chun-Yuan; Cheng, Cheng-Shun; Huang, Jiun-Yan; Lee, Yen-Fu; Hsu, Ming-Hung; Lin, Feng-Chun; Wang, Hao-Ching; Lo, Chu-Fang; Yang, Shieh-Yueh; Wang, Han-Ching

2015-01-01

Shrimp white spot disease (WSD), which is caused by white spot syndrome virus (WSSV), is one of the world's most serious shrimp diseases. Our objective in this study was to use an immunomagnetic reduction (IMR) assay to develop a highly sensitive, automatic WSSV detection platform targeted against ICP11 (the most highly expressed WSSV protein). After characterizing the magnetic reagents (Fe3O4 magnetic nanoparticles coated with anti ICP11), the detection limit for ICP11 protein using IMR was approximately 2 x 10(-3) ng/ml, and the linear dynamic range of the assay was 0.1~1 x 10(6) ng/ml. In assays of ICP11 protein in pleopod protein lysates from healthy and WSSV-infected shrimp, IMR signals were successfully detected from shrimp with low WSSV genome copy numbers. We concluded that this IMR assay targeting ICP11 has potential for detecting the WSSV.

Establishment of a simple and quantitative immunospot assay for detecting anti-type II collagen antibody using an infrared fluorescence imaging system (IFIS).

PubMed

Ota, Shusuke; Kanazawa, Satoshi; Kobayashi, Masaaki; Otsuka, Takanobu; Okamoto, Takashi

2005-04-01

Antibodies to type II collagen (col II) have been detected in patients with rheumatoid arthritis and in animal models of collagen induced arthritis. Here, we describe a novel method to detect anti-col II antibodies using an immunospot assay with an infrared fluorescence imaging system. This method showed very high sensitivity and specificity, and was simple, with low background levels. It also showed higher reproducibility and linearity, with a dynamic range of approximately 500-fold, than the conventional immunospot assay with enhanced chemiluminescence detection. Using this method we were able to demonstrate the antibody affinity maturation process in mice immunized with col II. In these immunized mice, although cross-reactive antibodies reacting with other collagen species were detected in earlier stages of immunization, the titers of cross-reactive antibodies rapidly diminished after the antigen boost, concomitantly with the elevation of the anti-col II antibody. The method and its possible applications are discussed.

Reverse phase protein microarrays: fluorometric and colorimetric detection.

PubMed

Gallagher, Rosa I; Silvestri, Alessandra; Petricoin, Emanuel F; Liotta, Lance A; Espina, Virginia

2011-01-01

The Reverse Phase Protein Microarray (RPMA) is an array platform used to quantitate proteins and their posttranslationally modified forms. RPMAs are applicable for profiling key cellular signaling pathways and protein networks, allowing direct comparison of the activation state of proteins from multiple samples within the same array. The RPMA format consists of proteins immobilized directly on a nitrocellulose substratum. The analyte is subsequently probed with a primary antibody and a series of reagents for signal amplification and detection. Due to the diversity, low concentration, and large dynamic range of protein analytes, RPMAs require stringent signal amplification methods, high quality image acquisition, and software capable of precisely analyzing spot intensities on an array. Microarray detection strategies can be either fluorescent or colorimetric. The choice of a detection system depends on (a) the expected analyte concentration, (b) type of microarray imaging system, and (c) type of sample. The focus of this chapter is to describe RPMA detection and imaging using fluorescent and colorimetric (diaminobenzidine (DAB)) methods.

Wind turbine blade shear web disbond detection using rotor blade operational sensing and data analysis.

PubMed

Myrent, Noah; Adams, Douglas E; Griffith, D Todd

2015-02-28

A wind turbine blade's structural dynamic response is simulated and analysed with the goal of characterizing the presence and severity of a shear web disbond. Computer models of a 5 MW offshore utility-scale wind turbine were created to develop effective algorithms for detecting such damage. Through data analysis and with the use of blade measurements, a shear web disbond was quantified according to its length. An aerodynamic sensitivity study was conducted to ensure robustness of the detection algorithms. In all analyses, the blade's flap-wise acceleration and root-pitching moment were the clearest indicators of the presence and severity of a shear web disbond. A combination of blade and non-blade measurements was formulated into a final algorithm for the detection and quantification of the disbond. The probability of detection was 100% for the optimized wind speed ranges in laminar, 30% horizontal shear and 60% horizontal shear conditions. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Design specification of an acousto-optic spectrum analyzer that could be used as an auxiliary receiver for CANEWS

NASA Astrophysics Data System (ADS)

Studenny, John; Johnstone, Eric

1991-01-01

The acousto-optic spectrum analyzer has undergone a theoretical design review and a basic parameter tradeoff analysis has been performed. The main conclusion is that for the given scenario of a 55 dB dynamic range and for a one-second temporal resolution, a 3.9 MHz resolution is a reasonable compromise with respect to current technology. Additional configurations are suggested. Noise testing of the signal detection processor algorithm was conducted. Additive white Gaussian noise was introduced to pure data. As expected, the tradeoff was between algorithm sensitivity and false alarms. No additional algorithm improvements could be made. The algorithm was observed to be robust, provided that the noise floor was set at a proper level. The digitization scheme was mainly driven by hardware constraints. To implement an analog to digital conversion scheme that linearly covers a 55 dB dynamic range would require a minimum of 17 bits. The general consensus was that 17 bits would be untenable for very large scale integration.

Digital Moiré based transient interferometry and its application in optical surface measurement

NASA Astrophysics Data System (ADS)

Hao, Qun; Tan, Yifeng; Wang, Shaopu; Hu, Yao

2017-10-01

Digital Moiré based transient interferometry (DMTI) is an effective non-contact testing methods for optical surfaces. In DMTI system, only one frame of real interferogram is experimentally captured for the transient measurement of the surface under test (SUT). When combined with partial compensation interferometry (PCI), DMTI is especially appropriate for the measurement of aspheres with large apertures, large asphericity or different surface parameters. Residual wavefront is allowed in PCI, so the same partial compensator can be applied to the detection of multiple SUTs. Excessive residual wavefront aberration results in spectrum aliasing, and the dynamic range of DMTI is limited. In order to solve this problem, a method based on wavelet transform is proposed to extract phase from the fringe pattern with spectrum aliasing. Results of simulation demonstrate the validity of this method. The dynamic range of Digital Moiré technology is effectively expanded, which makes DMTI prospective in surface figure error measurement for intelligent fabrication of aspheric surfaces.

Dynamic microwave assisted extraction coupled with dispersive micro-solid-phase extraction of herbicides in soybeans.

PubMed

Li, Na; Wu, Lijie; Nian, Li; Song, Ying; Lei, Lei; Yang, Xiao; Wang, Kun; Wang, Zhibing; Zhang, Liyuan; Zhang, Hanqi; Yu, Aimin; Zhang, Ziwei

2015-09-01

Non-polar solvent dynamic microwave assisted extraction was firstly applied to the treatment of high-fat soybean samples. In the dispersive micro-solid-phase extraction (D-µ-SPE), the herbicides in the high-fat extract were directly adsorbed on metal-organic frameworks MIL-101(Cr). The effects of several experimental parameters, including extraction solvent, microwave absorption medium, microwave power, volume and flow rate of extraction solvent, amount of MIL-101(Cr), and D-µ-SPE time, were investigated. At the optimal conditions, the limits of detection for the herbicides ranged from 1.56 to 2.00 μg kg(-1). The relative recoveries of the herbicides were in the range of 91.1-106.7%, and relative standard deviations were equal to or lower than 6.7%. The present method was simple, rapid and effective. A large amount of fat was also removed. This method was demonstrated to be suitable for treatment of high-fat samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Theta dynamics reveal domain-specific control over stimulus and response conflict.

PubMed

Nigbur, Roland; Cohen, Michael X; Ridderinkhof, K Richard; Stürmer, Birgit

2012-05-01

Cognitive control allows us to adjust to environmental changes. The medial frontal cortex (MFC) is thought to detect conflicts and recruit additional resources from other brain areas including the lateral prefrontal cortices. Here we investigated how the MFC acts in concert with visual, motor, and lateral prefrontal cortices to support adaptations of goal-directed behavior. Physiologically, these interactions may occur through local and long-range synchronized oscillation dynamics, particularly in the theta range (4-8 Hz). A speeded flanker task allowed us to investigate conflict-type-specific control networks for perceptual and response conflicts. Theta power over MFC was sensitive to both perceptual and response conflict. Interareal theta phase synchrony, however, indicated a selective enhancement specific for response conflicts between MFC and left frontal cortex as well as between MFC and the presumed motor cortex contralateral to the response hand. These findings suggest that MFC theta-band activity is both generally involved in conflict processing and specifically involved in linking a neural network controlling response conflict.

Mapping the spatial and temporal dynamics of the velvet mesquite with MODIS and AVIRIS: Case study at the Santa Rita Experimental Range

NASA Astrophysics Data System (ADS)

Kaurivi, Jorry Zebby Ujama

The general objective of this research is to develop a methodology that will allow mapping and quantifying shrub encroachment with remote sensing. The multitemporal properties of the Moderate Resolution Imaging Spectroradiometer (MODIS) -250m, 16-day vegetation index products were combined with the hyperspectral and high spatial resolution (3.6m) computation of the Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) to detect the dynamics of mesquite and grass/soil matrix at two sites of high (19.5%) and low (5.7%) mesquite cover in the Santa Rita Experimental Range (SRER). MODIS results showed separability between grassland and mesquite based on phenology. Mesquite landscapes had longer green peak starting in April through February, while the grassland only peaked during the monsoon season (July through October). AVIRIS revealed spectral separability, but high variation in the data implicated high heterogeneity in the landscape. Nonetheless, the methodology for larger data was developed in this study and combines ground, air and satellite data.

High dynamic range bio-molecular ion microscopy with the Timepix detector.

PubMed

Jungmann, Julia H; MacAleese, Luke; Visser, Jan; Vrakking, Marc J J; Heeren, Ron M A

2011-10-15

Highly parallel, active pixel detectors enable novel detection capabilities for large biomolecules in time-of-flight (TOF) based mass spectrometry imaging (MSI). In this work, a 512 × 512 pixel, bare Timepix assembly combined with chevron microchannel plates (MCP) captures time-resolved images of several m/z species in a single measurement. Mass-resolved ion images from Timepix measurements of peptide and protein standards demonstrate the capability to return both mass-spectral and localization information of biologically relevant analytes from matrix-assisted laser desorption ionization (MALDI) on a commercial ion microscope. The use of a MCP-Timepix assembly delivers an increased dynamic range of several orders of magnitude. The Timepix returns defined mass spectra already at subsaturation MCP gains, which prolongs the MCP lifetime and allows the gain to be optimized for image quality. The Timepix peak resolution is only limited by the resolution of the in-pixel measurement clock. Oligomers of the protein ubiquitin were measured up to 78 kDa. © 2011 American Chemical Society

High Resolution SOFIA/EXES Spectroscopy of CH4 and SO2 toward Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Boogert, Abraham C. A.; Richter, Matt; DeWitt, Curtis; Indriolo, Nick; Neufeld, David A.; Karska, Agata; Bergin, Edwin A.; Smith, Rachel L.; Montiel, Edward

2017-01-01

The ro-vibrational transitions of molecules in the near to mid-infrared are excellent tracers of the composition, dynamics, and excitation of the inner regions of Young Stellar Objects (YSOs). They sample a wide range of excitations in a short wavelength range, they can be seen in absorption against strong hot dust continuum sources, and they trace molecules without permanent dipole moment not observable at radio wavelengths. In particular, at high infrared spectral resolution, spatial scales smaller than those imaged by millimeter wave interferometers can be studied dynamically.We present high resolution (R=λ/Δλ˜50,000-100,000 6-12 km/s) infrared (7-8 μm) spectra of massive YSOs observed with the Echelon-Cross-Echelle Spectrograph (EXES) on the Stratospheric Observatory For Infrared Astronomy (SOFIA). Absorption lines of gas phase methane (CH4) are detected in our Cycle 2 observations. CH4 is thought to be a starting point of the formation of carbon chain molecules. Abundances are derived in the different dynamical regions along the sight-line towards the central star by comparing the line profiles to those of CO and other species observed at ground based facilities such as EXES' sister instrument TEXES at IRTF and Gemini. A search is also conducted for sulfur-dioxide, using data from our ongoing Cycle 4 program. SO2 was previously detected towards these massive YSOs with the space-based ISO/SWS instrument (Keane et al. 2001, A&A 376, L5) at much lower spectral resolution (R˜2,000). At high spectral resolution we should be able to pin-point the dynamical location of this SO2 gas. Up to 98% of the sulfur in dense clouds and protostellar envelopes is presently missing, and we are searching for that with the EXES/SOFIA observations.

Advanced Video Guidance Sensor (AVGS) Development Testing

NASA Technical Reports Server (NTRS)

Howard, Richard T.; Johnston, Albert S.; Bryan, Thomas C.; Book, Michael L.

2004-01-01

NASA's Marshall Space Flight Center was the driving force behind the development of the Advanced Video Guidance Sensor, an active sensor system that provides near-range sensor data as part of an automatic rendezvous and docking system. The sensor determines the relative positions and attitudes between the active sensor and the passive target at ranges up to 300 meters. The AVGS uses laser diodes to illuminate retro-reflectors in the target, a solid-state camera to detect the return from the target, and image capture electronics and a digital signal processor to convert the video information into the relative positions and attitudes. The AVGS will fly as part of the Demonstration of Autonomous Rendezvous Technologies (DART) in October, 2004. This development effort has required a great deal of testing of various sorts at every phase of development. Some of the test efforts included optical characterization of performance with the intended target, thermal vacuum testing, performance tests in long range vacuum facilities, EMI/EMC tests, and performance testing in dynamic situations. The sensor has been shown to track a target at ranges of up to 300 meters, both in vacuum and ambient conditions, to survive and operate during the thermal vacuum cycling specific to the DART mission, to handle EM1 well, and to perform well in dynamic situations.

Multi-scale compositionality: identifying the compositional structures of social dynamics using deep learning.

PubMed

Peng, Huan-Kai; Marculescu, Radu

2015-01-01

Social media exhibit rich yet distinct temporal dynamics which cover a wide range of different scales. In order to study this complex dynamics, two fundamental questions revolve around (1) the signatures of social dynamics at different time scales, and (2) the way in which these signatures interact and form higher-level meanings. In this paper, we propose the Recursive Convolutional Bayesian Model (RCBM) to address both of these fundamental questions. The key idea behind our approach consists of constructing a deep-learning framework using specialized convolution operators that are designed to exploit the inherent heterogeneity of social dynamics. RCBM's runtime and convergence properties are guaranteed by formal analyses. Experimental results show that the proposed method outperforms the state-of-the-art approaches both in terms of solution quality and computational efficiency. Indeed, by applying the proposed method on two social network datasets, Twitter and Yelp, we are able to identify the compositional structures that can accurately characterize the complex social dynamics from these two social media. We further show that identifying these patterns can enable new applications such as anomaly detection and improved social dynamics forecasting. Finally, our analysis offers new insights on understanding and engineering social media dynamics, with direct applications to opinion spreading and online content promotion.

Multi-Scale Compositionality: Identifying the Compositional Structures of Social Dynamics Using Deep Learning

PubMed Central

Peng, Huan-Kai; Marculescu, Radu

2015-01-01

Objective Social media exhibit rich yet distinct temporal dynamics which cover a wide range of different scales. In order to study this complex dynamics, two fundamental questions revolve around (1) the signatures of social dynamics at different time scales, and (2) the way in which these signatures interact and form higher-level meanings. Method In this paper, we propose the Recursive Convolutional Bayesian Model (RCBM) to address both of these fundamental questions. The key idea behind our approach consists of constructing a deep-learning framework using specialized convolution operators that are designed to exploit the inherent heterogeneity of social dynamics. RCBM’s runtime and convergence properties are guaranteed by formal analyses. Results Experimental results show that the proposed method outperforms the state-of-the-art approaches both in terms of solution quality and computational efficiency. Indeed, by applying the proposed method on two social network datasets, Twitter and Yelp, we are able to identify the compositional structures that can accurately characterize the complex social dynamics from these two social media. We further show that identifying these patterns can enable new applications such as anomaly detection and improved social dynamics forecasting. Finally, our analysis offers new insights on understanding and engineering social media dynamics, with direct applications to opinion spreading and online content promotion. PMID:25830775

Single-Molecule Spectroscopy and Imaging Studies of Protein Dynamics

NASA Astrophysics Data System (ADS)

Lu, H. Peter

2012-04-01

Enzymatic reactions and protein-protein interactions are traditionally studied at the ensemble level, despite significant static and dynamic inhomogeneities. Subtle conformational changes play a crucial role in protein functions, and these protein conformations are highly dynamic rather than being static. We applied AFM-enhanced single-molecule spectroscopy to study the mechanisms and dynamics of enzymatic reactions involved with kinase and lysozyme proteins. Enzymatic reaction turnovers and the associated structure changes of individual protein molecules were observed simultaneously in real-time by single-molecule FRET detections. Our single-molecule spectroscopy measurements of T4 lysozyme and HPPK enzymatic conformational dynamics have revealed time bunching effect and intermittent coherence in conformational state change dynamics involving in enzymatic reaction cycles. The coherent conformational state dynamics suggests that the enzymatic catalysis involves a multi-step conformational motion along the coordinates of substrate-enzyme complex formation and product releasing, presenting as an extreme dynamic behavior intrinsically related to the time bunching effect that we have reported previously. Our results of HPPK interaction with substrate support a multiple-conformational state model, being consistent with a complementary conformation selection and induced-fit enzymatic loop-gated conformational change mechanism in substrate-enzyme active complex formation. Our new approach is applicable to a wide range of single-molecule FRET measurements for protein conformational changes under enzymatic reactions.

Use of Protein G Microcolumns in Chromatographic Immunoassays: A Comparison of Competitive Binding Formats

PubMed Central

Pfaunmiller, Erika L.; Anguizola, Jeanethe A.; Milanuk, Mitchell L.; Carter, NaTasha; Hage, David S.

2016-01-01

Affinity microcolumns containing protein G were used as general platforms for creating chromatographic-based competitive binding immunoassays. Human serum albumin (HSA) was used as a model target for this work and HSA tagged with a near infrared fluorescent dye was utilized as the label. The protein G microcolumns were evaluated for use in several assay formats, including both solution-based and column-based competitive binding immunoassays and simultaneous or sequential injection formats. All of these methods were characterized by using the same amounts of labeled HSA and anti-HSA antibodies per sample, as chosen for the analysis of a protein target in the low-to-mid ng/mL range. The results were used to compare these formats in terms of their response, precision, limits of detection, and analysis time. All these methods gave detection limits in the range of 8–19 ng/mL and precisions ranging from ± 5% to ± 10% when using an injection flow rate of 0.10 mL/min. The column-based sequential injection immunoassay provided the best limit of detection and the greatest change in response at low target concentrations, while the solution-based simultaneous injection method had the broadest linear and dynamic ranges. These results provided valuable guidelines that can be employed to develop and extend the use of protein G microcolumns and these competitive binding formats to other protein biomarkers or biological agents of clinical or pharmaceutical interest. PMID:26777776

Diffusing-wave spectroscopy in a standard dynamic light scattering setup

NASA Astrophysics Data System (ADS)

Fahimi, Zahra; Aangenendt, Frank J.; Voudouris, Panayiotis; Mattsson, Johan; Wyss, Hans M.

2017-12-01

Diffusing-wave spectroscopy (DWS) extends dynamic light scattering measurements to samples with strong multiple scattering. DWS treats the transport of photons through turbid samples as a diffusion process, thereby making it possible to extract the dynamics of scatterers from measured correlation functions. The analysis of DWS data requires knowledge of the path length distribution of photons traveling through the sample. While for flat sample cells this path length distribution can be readily calculated and expressed in analytical form; no such expression is available for cylindrical sample cells. DWS measurements have therefore typically relied on dedicated setups that use flat sample cells. Here we show how DWS measurements, in particular DWS-based microrheology measurements, can be performed in standard dynamic light scattering setups that use cylindrical sample cells. To do so we perform simple random-walk simulations that yield numerical predictions of the path length distribution as a function of both the transport mean free path and the detection angle. This information is used in experiments to extract the mean-square displacement of tracer particles in the material, as well as the corresponding frequency-dependent viscoelastic response. An important advantage of our approach is that by performing measurements at different detection angles, the average path length through the sample can be varied. For measurements performed on a single sample cell, this gives access to a wider range of length and time scales than obtained in a conventional DWS setup. Such angle-dependent measurements also offer an important consistency check, as for all detection angles the DWS analysis should yield the same tracer dynamics, even though the respective path length distributions are very different. We validate our approach by performing measurements both on aqueous suspensions of tracer particles and on solidlike gelatin samples, for which we find our DWS-based microrheology data to be in good agreement with rheological measurements performed on the same samples.

Super-duper chemiluminescent proteins applicable to wide range of bioimaging

NASA Astrophysics Data System (ADS)

Suzuki, Kazushi; Nagai, Takeharu

2017-02-01

We report five new spectral variants of bright luminescent protein made by concatenation of the brightest luciferase, NanoLuc, with various color hues of fluorescent proteins. These proteins, which we call enhanced Nano-lanterns (eNLs), allow five-color live-cell imaging without external light illumination as well as detection of single molecules. Furthermore, eNL-based Ca2+ indicators could be used to image long-term Ca2+ dynamics in iPS-derived cardiomyocytes.

A Dynamic Bioinspired Neural Network Based Real-Time Path Planning Method for Autonomous Underwater Vehicles

PubMed Central

2017-01-01

Real-time path planning for autonomous underwater vehicle (AUV) is a very difficult and challenging task. Bioinspired neural network (BINN) has been used to deal with this problem for its many distinct advantages: that is, no learning process is needed and realization is also easy. However, there are some shortcomings when BINN is applied to AUV path planning in a three-dimensional (3D) unknown environment, including complex computing problem when the environment is very large and repeated path problem when the size of obstacles is bigger than the detection range of sensors. To deal with these problems, an improved dynamic BINN is proposed in this paper. In this proposed method, the AUV is regarded as the core of the BINN and the size of the BINN is based on the detection range of sensors. Then the BINN will move with the AUV and the computing could be reduced. A virtual target is proposed in the path planning method to ensure that the AUV can move to the real target effectively and avoid big-size obstacles automatically. Furthermore, a target attractor concept is introduced to improve the computing efficiency of neural activities. Finally, some experiments are conducted under various 3D underwater environments. The experimental results show that the proposed BINN based method can deal with the real-time path planning problem for AUV efficiently. PMID:28255297

A Dynamic Bioinspired Neural Network Based Real-Time Path Planning Method for Autonomous Underwater Vehicles.

PubMed

Ni, Jianjun; Wu, Liuying; Shi, Pengfei; Yang, Simon X

2017-01-01

Real-time path planning for autonomous underwater vehicle (AUV) is a very difficult and challenging task. Bioinspired neural network (BINN) has been used to deal with this problem for its many distinct advantages: that is, no learning process is needed and realization is also easy. However, there are some shortcomings when BINN is applied to AUV path planning in a three-dimensional (3D) unknown environment, including complex computing problem when the environment is very large and repeated path problem when the size of obstacles is bigger than the detection range of sensors. To deal with these problems, an improved dynamic BINN is proposed in this paper. In this proposed method, the AUV is regarded as the core of the BINN and the size of the BINN is based on the detection range of sensors. Then the BINN will move with the AUV and the computing could be reduced. A virtual target is proposed in the path planning method to ensure that the AUV can move to the real target effectively and avoid big-size obstacles automatically. Furthermore, a target attractor concept is introduced to improve the computing efficiency of neural activities. Finally, some experiments are conducted under various 3D underwater environments. The experimental results show that the proposed BINN based method can deal with the real-time path planning problem for AUV efficiently.

A photodiode amplifier system for pulse-by-pulse intensity measurement of an x-ray free electron laser.

PubMed

Kudo, Togo; Tono, Kensuke; Yabashi, Makina; Togashi, Tadashi; Sato, Takahiro; Inubushi, Yuichi; Omodani, Motohiko; Kirihara, Yoichi; Matsushita, Tomohiro; Kobayashi, Kazuo; Yamaga, Mitsuhiro; Uchiyama, Sadayuki; Hatsui, Takaki

2012-04-01

We have developed a single-shot intensity-measurement system using a silicon positive-intrinsic-negative (PIN) photodiode for x-ray pulses from an x-ray free electron laser. A wide dynamic range (10(3)-10(11) photons/pulse) and long distance signal transmission (>100 m) were required for this measurement system. For this purpose, we developed charge-sensitive and shaping amplifiers, which can process charge pulses with a wide dynamic range and variable durations (ns-μs) and charge levels (pC-μC). Output signals from the amplifiers were transmitted to a data acquisition system through a long cable in the form of a differential signal. The x-ray pulse intensities were calculated from the peak values of the signals by a waveform fitting procedure. This system can measure 10(3)-10(9) photons/pulse of ~10 keV x-rays by direct irradiation of a silicon PIN photodiode, and from 10(7)-10(11) photons/pulse by detecting the x-rays scattered by a diamond film using the silicon PIN photodiode. This system gives a relative accuracy of ~10(-3) with a proper gain setting of the amplifiers for each measurement. Using this system, we succeeded in detecting weak light at the developmental phase of the light source, as well as intense light during lasing of the x-ray free electron laser. © 2012 American Institute of Physics

Development of a thyroperoxidase inhibition assay for high ...

EPA Pesticide Factsheets

High-throughput screening (HTPS) assays to detect inhibitors of thyroperoxidase (TPO), the enzymatic catalyst for thyroid hormone (TH) synthesis, are not currently available. Herein we describe the development of a HTPS TPO inhibition assay. Rat thyroid microsomes and a fluorescent peroxidase substrate, Amplex UltraRed (AUR, LifeTechnologies), were employed in an endpoint assay for comparison to the existing kinetic guaiacol (GUA) oxidation assay. Following optimization of assay metrics including Z’, dynamic range, and activity using methimazole (MMI), the assay was tested with a 21-chemical training set. The potency of MMI-induced TPO inhibition was greater with AUR compared to GUA. The dynamic range and Z’ score with MMI were as follows: 127-fold and 0.62 for the GUA assay, 18-fold and 0.86 for the 96-well AUR assay, and 11.5-fold and 0.93 for the 384-well AUR assay. The 384-well AUR assay drastically reduced animal use, requiring one-tenth of the rat thyroid microsomal protein needed for the GUA 96-well format assay. Fourteen chemicals inhibited TPO, with a relative potency ranking of MMI > ethylene thiourea > 6-propylthiouracil > 2,2’,4,4’-tetrahydroxy-benzophenone > 2-mercaptobenzothiazole > 3-amino-1,2,4-triazole > genistein > 4-propoxyphenol > sulfamethazine > daidzein > 4-nonylphenol > triclosan > iopanoic acid > resorcinol. These data demonstrate the capacity of this assay to detect diverse TPO inhibitors. Seven chemicals acted as negati

Asymmetric exponential amplification reaction on a toehold/biotin featured template: an ultrasensitive and specific strategy for isothermal microRNAs analysis

PubMed Central

Chen, Jun; Zhou, Xueqing; Ma, Yingjun; Lin, Xiulian; Dai, Zong; Zou, Xiaoyong

2016-01-01

The sensitive and specific analysis of microRNAs (miRNAs) without using a thermal cycler instrument is significant and would greatly facilitate biological research and disease diagnostics. Although exponential amplification reaction (EXPAR) is the most attractive strategy for the isothermal analysis of miRNAs, its intrinsic limitations of detection efficiency and inevitable non-specific amplification critically restrict its use in analytical sensitivity and specificity. Here, we present a novel asymmetric EXPAR based on a new biotin/toehold featured template. A biotin tag was used to reduce the melting temperature of the primer/template duplex at the 5′ terminus of the template, and a toehold exchange structure acted as a filter to suppress the non-specific trigger of EXPAR. The asymmetric EXPAR exhibited great improvements in amplification efficiency and specificity as well as a dramatic extension of dynamic range. The limit of detection for the let-7a analysis was decreased to 6.02 copies (0.01 zmol), and the dynamic range was extended to 10 orders of magnitude. The strategy enabled the sensitive and accurate analysis of let-7a miRNA in human cancer tissues with clearly better precision than both standard EXPAR and RT-qPCR. Asymmetric EXPAR is expected to have an important impact on the development of simple and rapid molecular diagnostic applications for short oligonucleotides. PMID:27257058

Image plates as x-ray detectors in plasma physics experiments

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

Gales, S.G.; Bentley, C.D.

2004-10-01

The performance of image plates based on the photostimulable phosphor BaF(Br,l):Eu{sup 2+} has been investigated and compared with x-ray film. Evaluation of detective quantum efficiency (DQE), sensitivity, dynamic range, and linearity was carried out for several types of commercially available image plate, using the Excalibur soft x-ray calibration facility at AWE. Image plate response was found to be linear over a dynamic range of 5 orders of magnitude. One type of image plate was found to have a number of advantages for soft x-ray detection, with a measured sensitivity 1 order of magnitude greater than that of Kodak Industrex CXmore » and DEF-5 x-ray film. The DQE of this plate was found to be superior to that of film at low [less than 10{sup 3} photons/(50 {mu}m){sup 2}] and high fluxes [greater than 10{sup 4} photons/(50 {mu}m){sup 2}]. The spatial resolution of image plates, scanned with several models of commercial image plate readers, has been evaluated using a USAF resolution test target. The highest spatial resolution measured is 35 {mu}m. Though this is significantly lower than the resolution possible with film, it is sufficient for many applications. Image plates were fielded in a refractive x-ray lens imaging diagnostic on the 1 TW Helen laser and these results are discussed.« less