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1

Energy model for contrast detection: spatiotemporal characteristics of threshold vision.  

PubMed

A model for contrast detection of spatiotemporal stimuli is proposed which consists of a spatiotemporal linear filter, an energy device and a threshold device. Assuming the existence of independent intrinsic noise, the probability of stimulus detection was approximated by a Weibull function of the response energy. With this assumption, the stimulus energy is a constant at fixed detection probability. This energy model for contrast detection satisfactorily accounted for the elliptical threshold contours of line pairs at stimulus separations within the range 2-30 min and at stimulus onset asynchronies within the range 20-140 ms. The threshold contour at a large stimulus onset asynchrony (300 ms) was in the form of a rounded square. This finding was explained by assuming that the probability of seeing the line pair was determined by the joint probability that at least one stimulus had been detected. With the energy model, the temporal and spatial autocorrelation functions of the response to a flashed line were evaluated. The autocorrelation functions thus determined were used to predict the temporal contrast sensitivity function to a flickering line stimulus and the spatial contrast sensitivity function to flashed gratings, which were in agreement with the experimental data. The data obtained were fitted adequately by an impulse response approximated by a spatiotemporal Gabor-like function. PMID:10434391

Manahilov, V; Simpson, W

1999-07-01

2

Heartbeat detection using energy thresholding and template match.  

PubMed

Heartbeat detection is very important for retrieving the vital signs of heart functions. The morphologies and inter-beat intervals of heartbeats can reveal the condition of heart contraction. In this paper, we developed a heartbeat information integration scheme to deal with the information yielded by the energy thresholding and template match methods, which are usually used to detect the heartbeats and match the QRS, respectively. The proposed method are developed in SIMULINK 2.0 and assessed by the MIT/BIH arrhythmia database. The result demonstrated excellent sensitivity of detecting QRS and ventricular premature contraction in the proposed method. PMID:17281802

Chan, H L; Chen, G U; Lin, M A; Fang, S C

2005-01-01

3

Canonically optimum threshold detection  

Microsoft Academic Search

A general canonical theory is developed for the systematic approximation of optimum, or Bayes, detection procedures in the critical limiting threshold mode of operation. The approximations to Bayes detectors introduced here are called locally optimum Bayes detectors (LOBD's) and are defined by the condition that they produce the same value of average risk and its derivative for vanishingly small input

D. Middleton

1966-01-01

4

Joint optimization of sensing threshold and transmission power in wideband cognitive radio with energy detection  

NASA Astrophysics Data System (ADS)

this paper, we consider a wideband cognitive radio system that operates over multiple idle subchannels. A joint optimization of sensing threshold and transmission power is proposed, which maximizes the total throughput subject to the constraints on the total interference, the total power, and the probabilities of false alarm and detection of each subchannel. An alternative joint optimization is proposed, which minimizes the total interference under the constraint of the total throughput. The bilevel optimization method is used to solve the proposed optimization problems with a minimized iteration complexity. The mixed-variable optimization problem is divided into two single-variable convex optimization subproblems: the upper level for threshold optimization and the lower level for power optimization. Weighed cooperative sensing is proposed to maximize the detection probability by choosing the optimal weighed factors. The simulations show that the proposed joint optimization algorithm can achieve desirable improvement on the throughput of cognitive radio at the same interference level to primary user, or vice versa within the limits on the probabilities of false alarm and miss detection, and the weighed cooperative sensing can considerably improve sensing performance compared with the unweighed cooperative sensing and single-user sensing.

Liu, Xin; Bi, Guoan; Jia, Min; Guan, Yong Liang; Zhong, Weizhi; Lin, Rui

2013-07-01

5

Detection thresholds of macaque otolith afferents  

PubMed Central

The vestibular system is our sixth sense and is important for spatial perception functions. Yet, the sensory detection and discrimination properties of vestibular neurons remain relatively unexplored. Here we have used signal detection theory to measure detection thresholds of otolith afferents using 1 Hz linear accelerations delivered along three cardinal axes. Direction detection thresholds were measured by comparing mean firing rates centered on response peak and trough (full-cycle thresholds) or by comparing peak/trough firing rates with spontaneous activity (half-cycle thresholds). Thresholds were similar for utricular and saccular afferents, as well as for lateral, fore-aft and vertical motion directions. When computed along the preferred direction, full-cycle direction detection thresholds were 7.54 and 3.01 cm/s2 for regular and irregular firing otolith afferents, respectively. Half-cycle thresholds were approximately double, with excitatory thresholds being half as large as inhibitory thresholds. The variability in threshold among afferents was directly related to neuronal gain and did not depend on spike count variance. The exact threshold values depended on both the time window used for spike count analysis and the filtering method used to calculate mean firing rate, although differences between regular and irregular afferent thresholds were independent of analysis parameters. The fact that minimum thresholds measured in macaque otolith afferents are of the same order of magnitude as human behavioral thresholds suggests that the vestibular periphery might determine the limit on our ability to detect or discriminate small differences in head movement, with little noise added during downstream processing.

Yu, Xiong-Jie; Dickman, J David; Angelaki, Dora E.

2012-01-01

6

Chemical sensing thresholds for mine detection dogs  

Microsoft Academic Search

Mine detection dogs have been found to be an effective method to locate buried landmines. The capabilities of the canine olfaction method are from a complex combination of training and inherent capacity of the dog for odor detection. The purpose of this effort was to explore the detection thresholds of a limited group of dogs that were trained specifically for

James M. Phelan; James L. Barnett

2002-01-01

7

Temporal change threshold detection imager  

Microsoft Academic Search

A 90×90 active pixel sensor (APS) achieves 2% in-pixel change\\/motion detection at 30f\\/s consuming 4.2mW. The 6T2C 25?m × 25 ?m pixel in 0.5 ?m 2P3M CMOS provides intensity readout, detection of change events and polarities. Event address and APS value output are asynchronous, facilitating compression. The imager is intended for low-power low-bandwidth surveillance network applications.

Udayan Mallik; Matthew Clapp; Edward Choi; Gert Cauwenberghs; Ralph Etienne-Cummings

2005-01-01

8

DICOM GSPS affects on contrast detection threshold  

NASA Astrophysics Data System (ADS)

While previous research has been done to determine the contrast detection threshold in medical images, we have found it difficult to translate the results into settings that can be used for the optimization of image quality. Since many of these papers were done before the widespread use of DICOM GSPS calibrated monitors, how the GSPS affects the detection threshold and whether the median background intensity shift has been minimized by GSPS remain unknown. We set out to determine if the median background affected the detection of a low-contrast object in a clustered lumpy background, which simulated a mammography image. Our results show that shifts in the median background intensity did not affect the detection performance. The contrast detection threshold appears close to +3 gray levels above the background.

Leong, David L.; Miner Haygood, Tamara; Whitman, Gary J.; Carkaci, Selin; Tchou, Philip M.; Brennan, Patrick C.

2010-03-01

9

Prediction of Modulation Detectability Thresholds for Line-Scan Displays.  

National Technical Information Service (NTIS)

Determination of the modulation detectability threshold for sinusoidal gratings is a prerequisite to several measures of image quality for line-scan imaging systems. To develop predictive models for these thresholds, an experiment was conducted to determi...

R. L. Keesee

1976-01-01

10

Saltiness and acidity: detection and recognition thresholds and their interaction near the threshold.  

PubMed

Interaction of saltiness and acidity at the threshold level was studied employing 35 to 40 young female panelists. As a 1st step, the detection and recognition thresholds of salt, rice vinegar, and rice black vinegar have been measured for each panelist. To investigate the above interaction, the thresholds have been again measured for each panelist of salt, but this time, vinegar at half the concentration of each panelist's detection threshold was added to the salt solution. Similar measurement has been performed for vinegars with salt at half the concentration of each panelist's detection threshold. The data analysis has been done in 2 ways, namely, (1) by using Student's t-test to detect the significant difference in average between the data with and without the added ingredient and (2) detecting significant deviations from zero in the individual shifts in 2 sensory tests among panelists who participated in the 2 measurements. In doing that, a conversion of the scale was necessary to correct the systematic skewness existing in the original data. As a result, both the detection and recognition thresholds of salt were decreased with the existence of the added vinegar ingredient (P < 0.001). This tendency was more pronounced with rice black vinegar than with rice vinegar. On the contrary, no significant changes in the threshold of both detection and recognition were observed when salt at the half concentration of the detection threshold was added to rice vinegar. The interaction therefore was found to be asymmetric. PMID:19490341

Hatae, Keiko; Takeutchi, Fujio; Sakamoto, Mariko; Ogasawara, Yasushi; Akano, Hirofumi

11

Detection of tactile stimuli. Thresholds of afferent units related to psychophysical thresholds in the human hand.  

PubMed Central

1. Psychophysical thresholds were determined at 162 points in the glabrous skin area of the human hand when slowly rising, triangular indentations of controlled amplitudes were delivered with a small probe. The method of constant stimuli was used with either the two alternative forced choice or the yes-no procedure. It was found that the distribution of the psychophysical thresholds varied with the skin region. Thresholds from the volar aspect of the fingers and the peripheral parts of the palm were low and their distribution was unimodal with a median of 11.2 micrometers. In contrast, there was an over-representation of high thresholds when observations from the centre of the palm, the lateral aspects of the fingers and the regions of the creases were pooled, and the distribution was slightly bimodal with a median of 36.0 micrometers. 2. Nerve impulses were recorded from single fibres in the median nerve of human subjects with percutaneously inserted tungsten needle electrodes. The thresholds of 128 mechanosensitive afferent units in the glabrous skin area of the hand were determined when stimuli were delivered to partly the same points as stimulated for the assessment of the psychophysical thresholds. Of the four types of units present in this area the Pacinian corpuscle (PC) and rapidly adapting (RA) units had the lowest thresholds with medians of 9.2 and 13.8 micrometers, followed by the slowly adapting type I and slowly adapting type II units with medians of 56.5 and 33.1 micrometers. There was no indication of a difference between thresholds of units located in different skin areas. 3. In the region of low psychophysical thresholds there was good agreement between the thresholds of the rapidly adapting and Pacinian corpuscle units and the psychophysical thresholds, particularly at the lower ends of the samples. In the skin regions of high thresholds, on the other hand, practically all psychophysical thresholds were higher than the thresholds of the most sensitive afferent units. Moreover, simultaneous recording of nerve impulses during a detection task indicated that subjects did not detect stimuli strong enough to elicit several impulses in afferent units in this region. 4. Circumstantial evidence led to the conclusion that detection was dependent on one impulse in one or a few rapidly adapting units under optimal conditons in the region of low psychophysical thresholds, whereas it seemed unlikely that activity in Pacinian corpuscle units was crucial. 5. The findings are consistent with the interpretation that human subjects are able to detect an input consisting of a single impulse in a single rapidly adapting unit.

Johansson, R S; Vallbo, A B

1979-01-01

12

Experimental and environmental factors affect spurious detection of ecological thresholds.  

PubMed

Threshold detection methods are increasingly popular for assessing nonlinear responses to environmental change, but their statistical performance remains poorly understood. We simulated linear change in stream benthic macroinvertebrate communities and evaluated the performance of commonly used threshold detection methods based on model fitting (piecewise quantile regression [PQR]), data partitioning (nonparametric change point analysis [NCPA]), and a hybrid approach (significant zero crossings [SiZer]). We demonstrated that false detection of ecological thresholds (type I errors) and inferences on threshold locations are influenced by sample size, rate of linear change, and frequency of observations across the environmental gradient (i.e., sample-environment distribution, SED). However, the relative importance of these factors varied among statistical methods and between inference types. False detection rates were influenced primarily by user-selected parameters for PQR (tau) and SiZer (bandwidth) and secondarily by sample size (for PQR) and SED (for SiZer). In contrast, the location of reported thresholds was influenced primarily by SED. Bootstrapped confidence intervals for NCPA threshold locations revealed strong correspondence to SED. We conclude that the choice of statistical methods for threshold detection should be matched to experimental and environmental constraints to minimize false detection rates and avoid spurious inferences regarding threshold location. PMID:22486082

Daily, Jonathan P; Hitt, Nathaniel P; Smith, David R; Snyder, Craig D

2012-01-01

13

Alcohol influence on hemisphere differences and signal detection thresholds.  

PubMed

Six right- and six left-handed subjects were run in a repeated measures design to determine the influences of alcohol on hemiretina detection thresholds. Stimuli were presented tachistoscopically to the hemiretinae at blood alcohol concentrations (BACs) of 0, 50, and 100 mg%. The nasal hemiretinae had higher thresholds than the temporal hemiretinae and this difference was independent of alcohol. Alcohol interacted with visual field and handedness. The results showed that the highest alcohol dose (100 mg%) raised detection thresholds more for the hemifield contralateral to the subject's preferred hand than the ipsilateral hemified. Results are discussed in terms of lateral dominance and attention. PMID:417367

Damkot, D K; Frysinger, R C

1978-03-01

14

Threshold detection in generalized non-additive signals and noise  

SciTech Connect

The classical theory of optimum (binary-on-off) threshold detection for additive signals and generalized (i.e. nongaussian) noise is extended to the canonical nonadditive threshold situation. In the important (and usual) applications where the noise is sampled independently, a canonical threshold optimum theory is outlined here, which is found formally to parallel the earlier additive theory, including the critical properties of locally optimum Bayes detection algorithms, which are asymptotically normal and optimum as well. The important Class A clutter model provides an explicit example of optimal threshold envelope detection, for the non-additive cases of signal and noise. Various extensions are noted in the concluding section, as are selected references.

Middleton, D., LLNL

1997-12-22

15

Effect of lateral perturbations on psychophysical acceleration detection thresholds  

Microsoft Academic Search

BACKGROUND: In understanding how the human body perceives and responds to small slip-like motions, information on how one senses the slip is essential. The effect of aging and plantar sensory loss on detection of a slip can also be studied. Using psychophysical procedures, acceleration detection thresholds of small lateral whole-body perturbations were measured for healthy young adults (HYA), healthy older

Samantha J Richerson; Scott M Morstatt; Kristopher K O'Neal; Gloria Patrick; Charles J Robinson

2006-01-01

16

Optimal discrimination threshold for the detection of singlet oxygen luminescence  

NASA Astrophysics Data System (ADS)

Direct detection of singlet oxygen (1O2) luminescence around 1270 nm is the golden standard of 1O2 identification. In this study, the effect of the discrimination threshold on the detection of 1O2 luminescence that generated from the photoirradiation of Rose Bengal (RB) was evaluated by using a self-developed photon-counting detection system. The obtained results show that the discrimination threshold for photon counting has a significant impact on the intensity and shape of the measured 1O2 luminescence, which resulted in the variation of 1O2 lifetimes. The optimal discrimination threshold is determined to be about -0.0412 V, and the corresponding 1O2 lifetime in air-saturated distilled water is 4.26±0.06 ?s.

Chen, Defu; Lin, Huiyun; Shen, Yi; Li, Buhong; Xie, Shusen

2011-01-01

17

Mammographic calcification cluster detection and threshold gold thickness measurements  

NASA Astrophysics Data System (ADS)

European Guidelines for quality control in digital mammography specify acceptable and achievable standards of image quality (IQ) in terms of threshold gold thickness using the CDMAM test object. However, there is little evidence relating such measurements to cancer detection. This work investigated the relationship between calcification detection and threshold gold thickness. An observer study was performed using a set of 162 amorphous selenium direct digital (DR) detector images (81 no cancer and 81 with 1-3 inserted calcification clusters). From these images four additional IQs were simulated: different digital detectors (computed radiography (CR) and DR) and dose levels. Seven observers marked and rated the locations of suspicious regions. DBM analysis of variances was performed on the JAFROC figure of merit (FoM) yielding 95% confidence intervals for IQ pairs. Automated threshold gold thickness (Tg) analysis was performed for the 0.25mm gold disc diameter on CDMAM images at the same IQs (16 images per IQ). Tg was plotted against FoM and a power law fitted to the data. There was a significant reduction in FoM for calcification detection for CR images compared with DR; FoM decreased from 0.83 to 0.63 (p<=0.0001). Detection was also sensitive to dose. There was a good correlation between FoM and Tg (R2=0.80, p<0.05), consequently threshold gold thickness was a good predictor of calcification detection at the same IQ. Since the majority of threshold gold thicknesses for the various IQs were above the acceptable standard despite large variations in calcification detection by radiologists, current EU guidelines may need revising.

Warren, L. M.; Mackenzie, A.; Cooke, J.; Given-Wilson, R.; Wallis, M. G.; Chakraborty, D. P.; Dance, D. R.; Young, K. C.

2012-02-01

18

Two statistical methods for the detection of environmental thresholds  

Microsoft Academic Search

A nonparametric method and a Bayesian hierarchical modeling method are proposed in this paper for the detection of environmental thresholds. The nonparametric method is based on the reduction of deviance, while the Bayesian method is based on the change in the response variable distribution parameters. Both methods are tested using macroinvertebrate composition data from a mesocosm experiment conducted in the

Song S. Qian; Ryan S. King; Curtis J. Richardson

2003-01-01

19

Carbon monoxide exposure and human visual detection thresholds  

SciTech Connect

In order to test for low level CO exposure effects on vision, a battery of visual tests was administered to male college students. All subjects completed the battery of tests both before and during an exposure period in a double-blind study. Experimental subjects received CO during the exposure period, whereas control subjects received only room air. The battery of visual tests was designed for the assessment of scotopic (dark adapted, rod mediated) vision, photopic (light adapted, cone mediated) vision, the pattern detection process and the motion detection process. Contrast thresholds for the detection of stimulus pattern and for the detection of stimulus motion were measured under both photopic and scotopic viewing conditions, and sensitivity was monitored throughout the course of dark adaptation by measuring luminance thresholds. The results indicated that visual function in healthy, young adult males was not affected by a COHb level of about 17% which was maintained for over 2 hours.

Hudnell, H.K.; Benignus, V.A.

1989-01-01

20

Neutron threshold activation detectors (TAD) for the detection of fissions  

NASA Astrophysics Data System (ADS)

Prompt fission neutrons are one of the strongest signatures of the fission process. Depending on the fission inducing radiation, their average number ranges from 2.5 to 4 neutrons per fission. They are more energetic and abundant, by about 2 orders of magnitude, than the delayed neutrons (?3 vs. ?0.01) that are commonly used as indicators for the presence of fissionable materials.The detection of fission prompt neutrons, however, has to be done in the presence of extremely intense probing radiation that stimulated them. During irradiation, the fission stimulation radiation, X-rays or neutrons, overwhelms the neutron detectors and temporarily incapacitate them. Consequently, by the time the detectors recover from the source radiation, fission prompt neutrons are no longer emitted. In order to measure the prompt fission signatures under these circumstances, special measures are usually taken with the detectors such as heavy shielding with collimation, use of inefficient geometries, high pulse height bias and gamma-neutron separation via pulse-shape discrimination with an appropriate organic scintillator. These attempts to shield the detector from the flash of radiation result in a major loss of sensitivity. It can lead to a complete inability to detect the fission prompt neutrons.In order to overcome the blinding induced background from the source radiation, the detection of prompt fission neutrons needs to occur long after the fission event and after the detector has fully recovered from the source overload. A new approach to achieve this is to detect the delayed activation induced by the fission neutrons. The approach demonstrates a good sensitivity in adverse overload situations (gamma and neutron "flash") where fission prompt neutrons could normally not be detected.The new approach achieves the required temporal separation between the detection of prompt neutrons and the detector overload by the neutron activation of the detector material. The technique, called Threshold Activation Detection (TAD), is to utilize appropriate substances that can be selectively activated by the fission neutrons and not by the source radiation and then measure the radioactively decaying activation products (typically beta and gamma rays) well after the source pulse. The activation material should possess certain properties: a suitable half-life of the order of seconds; an energy threshold below which the numerous source neutrons will not activate it (e.g., 3 MeV); easily detectable activation products (typically >1 MeV beta and gamma rays) and have a usable cross-section for the selected reaction. Ideally the substance would be a part of the scintillator.There are several good material candidates for the TAD, including fluorine, which is a major constituent of available scintillators such as BaF2, CaF2 and hydrogen free liquid fluorocarbon. Thus the fluorine activation products, in particular the beta particles, can be measured with a very high efficiency in the detector.The principles, applications and experimental results obtained with the fluorine based TAD are discussed.

Gozani, Tsahi; Stevenson, John; King, Michael J.

2011-10-01

21

Detection thresholds for 60 Hz electric fields by nonhuman primates.  

PubMed

Because responses of animals to detection of the presence of an electric field (EF) are a possible mechanism for production of biological effects, it is important to know what EF intensities are detectable. Operant methods were used to train six baboons (Papio cynocephalus) to perform a psychophysical task involving detection of EF presence. During the response phase of a trial, a subject responded on one push button to report the presence of the EF and on a different push button to report the absence of the EF. Correct reports of EF presence of absence produced delivery of food rewards. The subjects became proficient at performing this psychophysical detection task; during 35 days of testing, false alarm rates averaged 9%. The average EF detection threshold was 12 kV/m; the range of means among subjects was 5-15 kV/m. Two special test procedures confirmed that the subjects were responding directly to EF presence of absence and not to artifacts that might be associated with EF generation. The EF detection threshold of nonhuman primates is similar to thresholds reported for rats and humans. PMID:8787564

Orr, J L; Rogers, W R; Smith, H D

1995-01-01

22

Using pyramids to define local thresholds for blob detection.  

PubMed

A method of detecting blobs in images is described. The method involves building a succession of lower resolution images and looking for spots in these images. A spot in a low resolution image corresponds to a distinguished compact region in a known position in the original image. Further, it is possible to calculate thresholds in the low resolution image, using very simple methods, and to apply those thresholds to the region of the original image corresponding to the spot. Examples are shown in which variations of the technique are applied to several images. PMID:21869118

Shneier, M

1983-03-01

23

Spin-system dynamics and fault detection in threshold networks  

SciTech Connect

We consider an agent on a fixed but arbitrary node of a known threshold network, with the task of detecting an unknown missing link. We obtain analytic formulas for the probability of success when the agent's tool is the free evolution of a single excitation on an XX spin system paired with the network. We completely characterize the parameters, which allows us to obtain an advantageous solution. From the results emerges an optimal (deterministic) algorithm for quantum search, from which a quadratic speedup with respect to the optimal classical analog and in line with well-known results in quantum computation is gained. When attempting to detect a faulty node, the chosen setting appears to be very fragile and the probability of success too small to be of any direct use.

Kirkland, Steve; Severini, Simone [Hamilton Institute, National University of Ireland, Maynooth County Kildare (Ireland); Department of Physics and Astronomy, University College London, WC1E 6BT London (United Kingdom)

2011-01-15

24

Dynamic threshold generators for robust fault detection in linear systems with parameter uncertainty  

Microsoft Academic Search

The problem of developing robust thresholds for fault detection is addressed. An inequality for the solution of a linear system with uncertain parameters is provided and is shown to be a valuable tool for developing dynamic threshold generators for fault detection. Such threshold generators are desirable for achieving robustness against model uncertainty in combination with sensitivity to small faults.The usefulness

Andreas Johansson; Michael Bask; Torbjörn Norlander

2006-01-01

25

Sparse representation based multi-threshold segmentation for hyperspectral target detection  

NASA Astrophysics Data System (ADS)

A sparse representation based multi-threshold segmentation (SRMTS) algorithm for target detection in hyperspectral images is proposed. Benefiting from the sparse representation, the high-dimensional spectral data can be characterized into a series of sparse feature vectors which has only a few nonzero coefficients. Through setting an appropriate threshold, the noise removed sparse spectral vectors are divided into two subspaces in the sparse domain consistent with the sample spectrum to separate the target from the background. Then a correlation and a vector 1-norm are calculated respectively in the subspaces. The sparse characteristic of the target is used to ext ract the target with a multi -threshold method. Unlike the conventional hyperspectral dimensionality reduction methods used in target detection algorithms, like Principal Components Analysis (PCA) and Maximum Noise Fraction (MNF), this algorithm maintains the spectral characteristics while removing the noise due to the sparse representation. In the experiments, an orthogonal wavelet sparse base is used to sparse the spectral information and a best contraction threshold to remove the hyperspectral image noise according to the noise estimation of the test images. Compared with co mmon algorithms, such as Adaptive Cosine Estimator (ACE), Constrained Energy Minimizat ion (CEM) and the noise removed MNF-CEM algorithm, the proposed algorithm demonstrates higher detection rates and robustness via the ROC curves.

Feng, Wei-yi; Chen, Qian; Miao, Zhuang; He, Wei-ji; Gu, Guo-hua; Zhuang, Jia-yan

2013-08-01

26

Comparison of computerized methods for detecting the ventilatory thresholds.  

PubMed

The aim of this study was to compare computerized automatic methods to detect the ventilatory threshold (VT). Thirty apparently healthy and physically active volunteers [22.5 (6.5) years; 1.72 (0.08) m; 71.9 (8.5) kg] were submitted to a progressive and maximal cycle exercise. The gas exchange was monitored breath-by-breath with a fast gas analyser. The VT and respiratory compensation (RC) were automatically detected based on the respiratory exchange ratio, the ventilatory equivalent for O2 and the ventilatory equivalent for CO2, pulmonary ventilation, end-tidal PO2 and PCO2, and v-slope. In addition, VT and RC were also determined independently by visual inspection by two experienced investigators, and the results were compared with those of the automatic procedures. The automatic VT averaged 77% of the maximal VO2 and the RC 88%. The agreement between the experienced observers was very close [mean difference: 44.4 (16.1) ml, r = 0.94, not significant]. Data were expressed as the mean value together with the standard deviation in each case. The automatic and visual inspection procedures did not present significant differences, resulting in 29.6 (29.6) ml with a reliability of r = 0.86. All methods were significantly correlated for VT and RC (r = 0.93 on average, P < 0.01). ANOVA did not show differences between either the VT methods (P = 0.131) or the RC methods (P = 0.41). In conclusion, the present study has compared several simultaneous breath-by-breath ergospirometric methods that are used to describe the anaerobic threshold, showing high confidence when compared to visual inspection. No statistical differences were found between the VT and RC techniques for physically active subjects indicating that these methods may be equally effectively employed. PMID:15349782

Santos, Edil Luis; Giannella-Neto, Antonio

2004-12-01

27

Effect of wine type on the detection threshold for diacetyl  

Microsoft Academic Search

Diacetyl, an important wine flavorant synthesized during alcoholic and malolactic fermentation, has been reported to have a sensory threshold of 2–3 mg\\/l. A comparative study of threshold for diacetyl in wines was undertaken to determine the effect of wine type on that value. Sensory threshold was determined according to the forced-choice ascending concentration series of limits method described by ASTM

Brigitte Martineau; Terry E. Acree; Thomas Henick-Kling

1995-01-01

28

Molecular dynamics simulation of threshold displacement energies in zircon  

SciTech Connect

Molecular-dynamics simulations were used to examine the displacement threshold energy (Ed) surface for Zr, Si and O in zircon using two different interatomic potentials. For each sublattice, the simulation was repeated from different initial conditions to estimate the uncertainty in the calculated value of Ed. The displacement threshold energies vary considerably with crystallographic direction and sublattice. The average displacement energy calculated with a recently developed transferable potential is about 120 and 60 eV for cations and anions, respectively. The oxygen displacement energy shows good agreement with experimental estimates in ceramics.

Moreira, Pedro A.; Devanathan, Ramaswami; Yu, Jianguo; Weber, William J.

2009-10-15

29

Determination of odour detection thresholds for acetic acid and ethyl acetate in ice wine  

Microsoft Academic Search

Collectively acetic acid and ethyl acetate are responsible for ‘volatile acidity’ (VA) in wine. The detection limit or threshold for these compounds is well documented in table wine but not for ice wine. Knowledge of the ice wine thresholds is important for understanding perception limits and setting legal standards, particularly for a product with high intrinsic concentrations. Thresholds were determined

Margaret A. Cliff; Gary J. Pickering

2006-01-01

30

An Algorithm for 353 Odor Detection Thresholds in Humans  

PubMed Central

One hundred and ninety three odor detection thresholds, ODTs, obtained by Nagata using the Japanese triangular bag method can be correlated as log (1/ODT) by a linear equation with R2 = 0.748 and a standard deviation, SD, of 0.830 log units; the latter may be compared with our estimate of 0.66 log units for the self-consistency of Nagata's data. Aldehydes, acids, unsaturated esters, and mercaptans were included in the equation through indicator variables that took into account the higher potency of these compounds. The ODTs obtained by Cometto-Muñiz and Cain, by Cometto-Muñiz and Abraham, and by Hellman and Small could be put on the same scale as those of Nagata to yield a linear equation for 353 ODTs with R2 = 0.759 and SD = 0.819 log units. The compound descriptors are available for several thousand compounds, and can be calculated from structure, so that further ODT values on the Nagata scale can be predicted for a host of volatile or semivolatile compounds.

Sanchez-Moreno, Ricardo; Cometto-Muniz, J. Enrique; Cain, William S.

2012-01-01

31

Modeling Associative Recognition: A Comparison of Two-High-Threshold, Two-High-Threshold Signal Detection, and Mixture Distribution Models  

ERIC Educational Resources Information Center

|A 2-high-threshold signal detection (HTSDT) model, a mixture distribution (SON) model, and 2-highthreshold (HT) models with responses distributed over 1 or several response categories were fit to results of 6 experiments from 2 studies on associative recognition: R. Kelley and J. T. Wixted (2001) and A. P. Yonelinas (1997). HTSDT assumes that…

Macho, Siegfried

2004-01-01

32

Modeling Associative Recognition: A Comparison of Two-High-Threshold, Two-High-Threshold Signal Detection, and Mixture Distribution Models  

ERIC Educational Resources Information Center

A 2-high-threshold signal detection (HTSDT) model, a mixture distribution (SON) model, and 2-highthreshold (HT) models with responses distributed over 1 or several response categories were fit to results of 6 experiments from 2 studies on associative recognition: R. Kelley and J. T. Wixted (2001) and A. P. Yonelinas (1997). HTSDT assumes that…

Macho, Siegfried

2004-01-01

33

Suboptimal Threshold Detection in Narrowband Non-Gaussian Noise.  

National Technical Information Service (NTIS)

The Middleton Class A narrowband non-Gaussian noise model is considered. The performance of various simple suboptimum threshold detectorss is examined and compared with the performance of the optimum detector. For example, it is shown that for most cases ...

K. S. Vastola S. C. Schwartz

1983-01-01

34

Efficient Shadow Detection of Color Aerial Images Based on Successive Thresholding Scheme  

Microsoft Academic Search

Recently, Tsai presented an efficient algorithm which uses the ratio value of the hue over the intensity to construct the ratio map for detecting shadows of color aerial images. Instead of only using the global thresholding process in Tsai's algorithm, this paper presents a novel successive thresholding scheme (STS) to detect shadows more accurately. In our proposed STS, the modified

Kuo-Liang Chung; Yi-Ru Lin; Yong-Huai Huang

2009-01-01

35

An efficient blood vessel detection algorithm for retinal images using local entropy thresholding  

Microsoft Academic Search

This paper presents an efficient method for automatic detection and extraction of blood vessels in retinal images. Specifically, we also delineate vascular intersections\\/crossovers. The proposed algorithm is composed of four steps: matched filtering, local entropy thresholding, length filtering, and vascular intersection detection. The purpose of matched filtering is to enhance the blood vessels. Entropy-based thresholding can well keep the spatial

Thitiporn Chanwimaluang; Guoliang Fan

2003-01-01

36

A multiobjective optimization approach to obtain decision thresholds for distributed detection in wireless sensor networks.  

PubMed

For distributed detection in a wireless sensor network, sensors arrive at decisions about a specific event that are then sent to a central fusion center that makes global inference about the event. For such systems, the determination of the decision thresholds for local sensors is an essential task. In this paper, we study the distributed detection problem and evaluate the sensor thresholds by formulating and solving a multiobjective optimization problem, where the objectives are to minimize the probability of error and the total energy consumption of the network. The problem is investigated and solved for two types of fusion schemes: 1) parallel decision fusion and 2) serial decision fusion. The Pareto optimal solutions are obtained using two different multiobjective optimization techniques. The normal boundary intersection (NBI) method converts the multiobjective problem into a number of single objective-constrained subproblems, where each subproblem can be solved with appropriate optimization methods and nondominating sorting genetic algorithm-II (NSGA-II), which is a multiobjective evolutionary algorithm. In our simulations, NBI yielded better and evenly distributed Pareto optimal solutions in a shorter time as compared with NSGA-II. The simulation results show that, instead of only minimizing the probability of error, multiobjective optimization provides a number of design alternatives, which achieve significant energy savings at the cost of slightly increasing the best achievable decision error probability. The simulation results also show that the parallel fusion model achieves better error probability, but the serial fusion model is more efficient in terms of energy consumption. PMID:19674955

Masazade, Engin; Rajagopalan, Ramesh; Varshney, Pramod K; Mohan, Chilukuri K; Sendur, Gullu Kiziltas; Keskinoz, Mehmet

2009-08-11

37

Wireless threshold sensors for detecting corrosion in reinforced concrete structures  

NASA Astrophysics Data System (ADS)

The long-term reliability of a threshold corrosion sensor is demonstrated using data collected during two series of exposure tests. The sensors were embedded in concrete and interrogated in a wireless manner using inductive coupling. The frequency signature of the sensor changes after a steel sensing wire corrodes, providing a convenient and noninvasive technique for determining when a threshold amount of corrosion has occurred in a reinforced concrete structure. In the first series of exposure tests, the sensors were embedded in concrete prisms, which were exposed to a variety of temperature and moisture conditions over a six-month period. In the second series of tests, the sensors were embedded in reinforced concrete slabs. The slabs have been subjected to sustained loads and alternating wet and dry cycles for the past year. Data from both test series indicate that the threshold sensors are functioning as designed.

Dickerson, Nathan P.; Andringa, Matthew M.; Puryear, John M.; Wood, Sharon L.; Neikirk, Dean P.

2006-04-01

38

Radiation damage in copper near the threshold energy  

Microsoft Academic Search

Radiation damage and annealing studies of copper samples have been performed for the near threshold energy region. A nonlinear behavior of the damage rate vs. irradiation fluence is found. This effect is related to damage which does not anneal below 300 K and is independent of subthreshold damage.

A. B. Pruitt; R. L. Chaplin

1971-01-01

39

Segmentation of forward-looking infrared image using fuzzy thresholding and edge detection  

Microsoft Academic Search

A new segmentation algorithm is proposed to extract a target in forward-looking IR (FLIR) images. It is based on fuzzy thresholding and edge detection. First, a region of interest (ROI) selection method is applied to the FLIR image to remove complex background and to automatically extract a small rectangular ROI including a target. Then fuzzy thresholding, which uses intensity and

SunGu Sun; Hyun Wook Park

2001-01-01

40

Seismicity and detection\\/location threshold in the Southern Great Basin seismic network  

Microsoft Academic Search

A spatially varying model of the detection\\/location capabilities of the Southern Great Basin seismic network (SGBSN) has been derived that is based on simple empirical relations and statistics. This permits use of almost all the catalog data gathered; instead of ignoring data that are below the threshold of completeness, a spatially varying threshold model is developed so that subregions having

Joan Gomberg

1991-01-01

41

Adjusting the low energy threshold for large bodies in PET  

Microsoft Academic Search

The performance of a PET scanner on three different phantom sizes was studied as a function of low energy threshold (LET). Phantom cross sections ranged from 20 cm diameter circular to 28 cmtimes43 cm oval and LET's ranged from 350 keV to 475 keV, in 25 keV increments. System sensitivity, scatter fraction, and NEC were measured over a wide range

Timothy G. Turkington; John W. Wilson; James G. Colsher

2004-01-01

42

Effect of ramp-like contours upon perceived size and detection threshold  

Microsoft Academic Search

Perceived widths and detection thresholds were measured for foveally viewed stimuli which were edged on two sides by luminance\\u000a ramps. Perceived width approximated the distance between the midpoints of the ramps. It varied with the width of the ramps,\\u000a but was unaffected by a five-fold change in the luminance of the stimulus. The detection threshold was higher for a ramp

J. P. Thomas; L. Kerr

1969-01-01

43

Behaviorally measured audiograms and gap detection thresholds in CBA\\/CaJ mice  

Microsoft Academic Search

Tone detection and temporal gap detection thresholds were determined in CBA\\/CaJ mice using a Go\\/No-go procedure and the psychophysical\\u000a method of constant stimuli. In the first experiment, audiograms were constructed for five CBA\\/CaJ mice. Thresholds were obtained\\u000a for eight pure tones ranging in frequency from 1 to 42 kHz. Audiograms showed peak sensitivity between 8 and 24 kHz, with\\u000a higher thresholds at

Kelly E. Radziwon; Kristie M. June; Daniel J. Stolzberg; Matthew A. Xu-Friedman; Richard J. Salvi; Micheal L. Dent

2009-01-01

44

Pressure Systems Stored-Energy Threshold Risk Analysis  

SciTech Connect

Federal Regulation 10 CFR 851, which became effective February 2007, brought to light potential weaknesses regarding the Pressure Safety Program at the Pacific Northwest National Laboratory (PNNL). The definition of a pressure system in 10 CFR 851 does not contain a limit based upon pressure or any other criteria. Therefore, the need for a method to determine an appropriate risk-based hazard level for pressure safety was identified. The Laboratory has historically used a stored energy of 1000 lbf-ft to define a pressure hazard; however, an analytical basis for this value had not been documented. This document establishes the technical basis by evaluating the use of stored energy as an appropriate criterion to establish a pressure hazard, exploring a suitable risk threshold for pressure hazards, and reviewing the methods used to determine stored energy. The literature review and technical analysis concludes the use of stored energy as a method for determining a potential risk, the 1000 lbf-ft threshold, and the methods used by PNNL to calculate stored energy are all appropriate. Recommendations for further program improvements are also discussed

Paulsen, Samuel S.

2009-08-25

45

Dynamo threshold detection in the von Kármán sodium experiment.  

PubMed

Predicting dynamo self-generation in liquid metal experiments has been an ongoing question for many years. In contrast to simple dynamical systems for which reliable techniques have been developed, the ability to predict the dynamo capacity of a flow and the estimate of the corresponding critical value of the magnetic Reynolds number (the control parameter of the instability) has been elusive, partly due to the high level of turbulent fluctuations of flows in such experiments (with kinetic Reynolds numbers in excess of 10(6)). We address these issues here, using the von Kármán sodium experiment and studying its response to an externally applied magnetic field. We first show that a dynamo threshold can be estimated from analysis related to critical slowing down and susceptibility divergence, in configurations for which dynamo action is indeed observed. These approaches are then applied to flow configurations that have failed to self-generate magnetic fields within operational limits, and we quantify the dynamo capacity of these configurations. PMID:23944544

Miralles, Sophie; Bonnefoy, Nicolas; Bourgoin, Mickael; Odier, Philippe; Pinton, Jean-François; Plihon, Nicolas; Verhille, Gautier; Boisson, Jean; Daviaud, François; Dubrulle, Bérengère

2013-07-08

46

Changes in tooth pulpal detection and pain thresholds in relation to jaw movement in man  

Microsoft Academic Search

The effect of jaw movements on pulpal sensory thresholds to electrical stimulation was studied in healthy humans. The movements consisted of repeated jaw opening and closing at two different frequencies (1 and 3 s?1). The detection\\/perception and pain thresholds of an upper or lower central incisor were determined by stimulation with monopolar constant current pulses at two different durations (0.5

P Kemppainen; I Vaalamo; N Leppälä; A Pertovaara

2001-01-01

47

THRESHOLDING FOR BIOLOGICAL MATERIAL DETECTION IN REAL-TIME MULTISPECTRAL IMAGING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recently, hyperspectral image analysis has proved successful for a target detection problem encountered in remote sensing as well as near sensing utilizing in situ instrumentation. The conventional global bi-level thresholding for target detection, such as the clustering-based Otsu’s method, has be...

48

Thresholding for biological material detection in real-time multispectral imaging  

NASA Astrophysics Data System (ADS)

Recently, hyperspectral image analysis has proved successful for a target detection problem encountered in remote sensing as well as near sensing utilizing in situ instrumentation. The conventional global bi-level thresholding for target detection, such as the clustering-based Otsu's method, has been inadequate for the detection of biologically harmful material on foods that has a large degree of variability in size, location, color, shape, texture, and occurrence time. This paper presents multistep-like thresholding based on kernel density estimation for the real-time detection of harmful contaminants on a food product presented in multispectral images. We are particularly concerned with the detection of fecal contaminants on poultry carcasses in real-time. In the past, we identified 2 optimal wavelength bands and developed a real-time multispectral imaging system using a common aperture camera and a globally optimized thresholding method from a ratio of the optimal bands. This work extends our previous study by introducing a new decision rule to detect fecal contaminants on a single bird level. The underlying idea is to search for statistical separability along the two directions defined by the global optimal threshold vector and its orthogonal vector. Experimental results with real birds and fecal samples in different amounts are provided.

Yoon, Seung Chul; Park, Bosoon; Lawrence, Kurt C.; Windham, William R.

2005-09-01

49

Human tactile detection thresholds: modification by inputs from specific tactile receptor classes  

PubMed Central

1. Human detection thresholds for a vibratory stimulus applied to the volar surface of the index finger were examined under conditions where afferents from specific tactile receptor classes were simultaneously activated from the thenar eminence. The experiments were designed to test whether stimuli which have been shown previously to induce afferent inhibition of `tactile' neurones in the cuneate nucleus of the cat could modify human subjective performance in a tactile detection task. Conditioning stimuli to the thenar eminence were usually of three forms; steady indentation to engage slowly adapting tactile receptors; 300 Hz vibration to engage Pacinian corpuscles; and 30 Hz vibration to engage the intradermal, rapidly adapting tactile receptors which are thought to be Meissner's corpuscles. 2. In ten subjects the mean detection threshold for a 30 Hz test stimulus in the absence of conditioning stimulation was 8·6 ± 1·0 ?m (S.E.). Detection thresholds were increased substantially in the presence of a 300 Hz, 100 ?m conditioning stimulus (mean increase 11·1 ± 2·0 ?m), whereas minor or insignificant effects were seen with conditioning stimuli consisting of (a) 30 Hz, 100 ?m (mean increase 1·4 ± 0·8 ?m), (b) steady indentation, 1·5 mm in amplitude (mean increase 1·3 ± 0·7 ?m) or (c) 300 Hz, 100 ?m to the contralateral thenar eminence (mean increase 0·4 ± 0·5 ?m). 3. The 300 Hz conditioning stimulus to the ipsilateral thenar eminence caused a marked increase in detection thresholds at all test stimulus frequencies over the range 10-450 Hz. The effects of the conditioning stimulation therefore operated on inputs from Pacinian corpuscles, which are responsible for vibration detection at 80-450 Hz, and on inputs from the intradermal, rapidly adapting receptors which are responsible for vibration detection at 10-80 Hz. 4. The band width of conditioning vibratory frequencies which was effective at amplitudes of 100 ?m in bringing about increases in detection threshold extended from 50-80 Hz to 300 Hz, the maximum tested. 5. Whereas amplitudes of 1-2 ?m produced clear increases in detection thresholds with conditioning stimuli of 300 Hz, amplitudes of > 200 ?m were needed at 30 Hz. 6. The observed elevations in detection threshold are consistent with an afferent-induced inhibitory action exerted at synaptic relays of the sensory pathway by tactile inputs arising exclusively or predominantly from Pacinian corpuscles.

Ferrington, D. G.; Nail, B. S.; Rowe, Mark

1977-01-01

50

Low-energy structure of above-threshold-ionization electron spectra: Role of the Coulomb threshold effect  

SciTech Connect

Recent experimental observations of above-threshold ionization of rare gas atoms and diatomic molecules by midinfrared laser fields [C. I. Blaga et al., Nat. Phys. 5, 335 (2009); W. Quan et al., Phys. Rev. Lett. 103, 093001 (2009)] revealed a prominent maximum in the electron energy spectrum very close to the ionization threshold which is not reproduced by widely used Keldysh-Faisal-Reiss theories. We have performed fully ab initio theoretical analysis and precision calculations to explore the quantum origin of the low-energy structure (LES) observed in the experiments. Our study shows that an important role in shaping of LES is played by the effect of Coulomb attraction in the final electron state and the Coulomb threshold effect.

Telnov, Dmitry A. [Department of Physics, St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Chu, Shih-I [Department of Chemistry, University of Kansas, Lawrence, Kansas 66045 (United States); Center for Quantum Science and Engineering, Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China)

2011-06-15

51

Low-energy structure of above-threshold-ionization electron spectra: Role of the Coulomb threshold effect  

NASA Astrophysics Data System (ADS)

Recent experimental observations of above-threshold ionization of rare gas atoms and diatomic molecules by midinfrared laser fields [C. I. Blaga , Nat. Phys.PRLTAO1745-247310.1038/nphys1228 5, 335 (2009); W. Quan , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.103.093001 103, 093001 (2009)] revealed a prominent maximum in the electron energy spectrum very close to the ionization threshold which is not reproduced by widely used Keldysh-Faisal-Reiss theories. We have performed fully ab initio theoretical analysis and precision calculations to explore the quantum origin of the low-energy structure (LES) observed in the experiments. Our study shows that an important role in shaping of LES is played by the effect of Coulomb attraction in the final electron state and the Coulomb threshold effect.

Telnov, Dmitry A.; Chu, Shih-I.

2011-06-01

52

Detecting modulated signals in modulated noise: (I) behavioural auditory thresholds in a songbird.  

PubMed

Most signals from the auditory world have temporal patterns of amplitude modulation that either emanate from the signal source or result from environmental interference (e.g. air turbulence). To investigate mechanisms associated with the segregation and processing of amplitude-modulated signals, we trained European starlings (Sturnus vulgaris) to detect a signal noise band embedded in several flanking noise bands (FBs). We manipulated the envelope correlation between the signal and FBs, the onset synchrony between signal and FBs (0 or100 ms), signal duration (60 or 400 ms) and the spectrum level of the FBs (15 or 50 dB). The lowest signal-detection thresholds were found when the envelopes of the FBs were correlated with each other but different from the signal envelope (the 'co-uncorrelated' condition). Detection thresholds were on average 7 dB higher when both the signal and the FBs had correlated envelopes (the 'all correlated' condition). Thresholds were even higher when the envelopes of all noise bands were independent (the 'all uncorrelated' condition). The difference in detection thresholds between the co-uncorrelated and the all correlated conditions is termed 'comodulation detection difference' (CDD). Differences in signal duration and masker level had significant effects on detection threshold, but not on CDD magnitudes; differences in onset synchrony had no effects. We compare data from starlings with those from previous psychoacoustic studies of humans, and discuss possible mechanisms on which these perceptual effects may rely. Our behavioural data are the reference for a companion study investigating CDD at the neuronal level of the starling [M.A. Bee et al. (2007) Eur. J. Neurosci., 26, 1979-1994]. PMID:17897400

Langemann, Ulrike; Klump, Georg M

2007-10-01

53

Signal detection theory and vestibular thresholds: I. Basic theory and practical considerations  

PubMed Central

Detection theory has been applied to the measurement of vestibular thresholds and vestibular sensory integration. Yet, a formal detection theory analysis of vestibular responses has not been published. Such a de novo analysis seems warranted because the vestibular system has characteristics that differ from other sensory systems, which impacts the application of detection theory. For example, the physical stimuli evoking vestibular responses are typically bidirectional (e.g., leftward/rightward); this bidirectional nature of vestibular responses leads to another characteristic—what is sometimes called vestibular bias—that must also be considered, since it can impact threshold measurements, including thresholds found using staircase procedures. This paper develops a basic model of vestibular noise and then analyzes this model for four standard paradigms—one-interval recognition, one-interval detection, two-interval detection, and two-interval recognition. While any of these paradigms might be justified for a specific application, it is concluded that one-interval recognition paradigms have advantages over other paradigms for many vestibular applications. One-interval recognition is favored over one-interval detection because it lends itself to a fixed detection boundary, is more efficient, and is less impacted by device vibration. One-interval recognition is generally favored over two-interval recognition because it assesses vestibular bias and can require substantially less time than two-interval tasks.

2011-01-01

54

Setting adaptive spike detection threshold for smoothed TEO based on robust statistics theory.  

PubMed

We propose a novel approach aimed at adaptively setting the threshold of the smoothed Teager energy operator (STEO) detector to be used in extracellular recording of neural signals. In this proposed approach, to set the adaptive threshold of the STEO detector, we derive the relationship between the low-order statistics of its input signal and the ones of its output signal. This relationship is determined with only the background noise component assumed to be present at the input. Robust statistics theory techniques were used to achieve an unbiased estimation of these low-order statistics of the background noise component directly from the neural input signal. In this paper, the emphasis is made on extracellular neural recordings. However, the proposed method can be used in the analysis of different biomedical signals where spikes are important for diagnostic (e.g., ECG, EEG, etc.). We validated the efficacy of the proposed method using synthetic neural signals constructed from real neural recordings signals. Four different sets of extracellular recordings from four distinct neural sources have been exploited to that purpose. The first dataset is recorded from an adult male monkey using the Utath 10×10 microelectrode array implemented in the prefrontal cortex, the second one was obtained from the visual cortex of a rat using a stainless-steel-tipped microelectrode, the third dataset came from recording in a human medial lobe using intracranial electrode, and finally, the fourth one was extracted from recordings in a macaque parietal cortex using a single tetrode. Simulation results show that our approach is effective and robust, and outperforms state-of-the-art adaptive detection methods in its category (i.e., efficient and simple, and do not require a priori knowledge about neural spike waveforms shapes). PMID:22084039

Semmaoui, Hicham; Drolet, Jonathan; Lakhssassi, Ahmed; Sawan, Mohamad

2011-11-07

55

A Hybrid Clustering Algorithm for Fire Detection in Video and Analysis with Color Based Thresholding Method  

Microsoft Academic Search

In this study an unsupervised way of fire pixel detection from video frames is depicted. A hybrid clustering algorithm is proposed, depending on color samples in video frames. A modified k-mean clustering algorithm is used here. In this algorithm hierarchical and partition clustering are used to build the hybrid. The results are analyzed with color base threshold method by considering

Ishita Chakraborty; Tanoy Kr. Paul

2010-01-01

56

Olfactory Detection Thresholds and Adaptation in Adults with Autism Spectrum Condition  

ERIC Educational Resources Information Center

|Sensory issues have been widely reported in Autism Spectrum Conditions (ASC). Since olfaction is one of the least investigated senses in ASC, the current studies explore olfactory detection thresholds and adaptation to olfactory stimuli in adults with ASC. 80 participants took part, 38 (18 females, 20 males) with ASC and 42 control participants…

Tavassoli, T.; Baron-Cohen, S.

2012-01-01

57

On the detection threshold for fatigue cracks in welded steel beams using vibration analysis  

Microsoft Academic Search

In this paper the influence of a surface fatigue crack on vibration behaviour of tee-welded plates was studied and results compared to the influence of machined through-thickness cuts on the dynamic response of cantilever beams. Comparison of experimental data with two and three dimension finite element modelling results was also carried out and discussed. Detection threshold using natural frequencies shift

G. E. Carr; M. D. Chapetti

2011-01-01

58

The impact model of cumulative damage on the detection threshold of space optical communication  

Microsoft Academic Search

In order to improve the radiation hardness of free-space optical communication system, this paper theoretically deduces the radiation damage model of laser diodes' output power. For this model, the theory of Gaussian distribution is used to study the radiation influence on detection threshold of free-space optical communication on the condition that the bit error rate keeps invariable. The result shows

Guolong Chang; Yanping Zhou; Jing Ma; Jianqiang Zhou; Bingnan Zhao; Xiaoming Wang; Yu Zhou; Xiaofang Lv

2010-01-01

59

Effects of d -methamphetamine on auditory and visual reaction times and detection thresholds in the baboon  

Microsoft Academic Search

Baboons were trained in both auditory and visual reaction time procedures to release a response lever in the presence of low-intensity stimuli. By varying the stimulus intensity from trial to trial, functions relating reaction time (elapsed time from stimulus onset to lever release) to stimulus intensity were established, and detection thresholds were measured. The effects of acute, IM injections of

Robert D. Hienz; Scott E. Lukas; Joseph V. Brady

1985-01-01

60

Retrospective Cluster Size Thresholding for MRF-based Detection of Activated Regions in fMRI  

Microsoft Academic Search

Detection of activation regions in functional Magnetic Resonance Imaging (fMRI) experiments can be improved by cluster size thresholding, where small regions are removed in the post-processing step. It is believed that such small regions are spurious and hence can be removed without affecting the truly activated ones. We show that in the context of Markov Random Field (MRF) based segmentation,

S. Suresh Anand; Vitali Zagorodnov

2006-01-01

61

Clairvoyant and adaptive signal detection in non-Gaussian clutter: a data-dependent threshold interpretation  

Microsoft Academic Search

This paper addresses the problem of signal detection in correlated non-Gaussian clutter modeled as a spherically invariant random process. The optimum strategy to detect a constant signal, with either known or unknown complex amplitude, embedded in correlated Gaussian clutter is given by comparing the whitening-matched filter output with a fixed threshold. When the clutter is non-Gaussian, the performance of the

Fulvio Gini; Maria V. Greco; Alfonso Farina

1999-01-01

62

Size-Change Detection Thresholds of a Hand-Held Bar at Rest and during Movement  

Microsoft Academic Search

\\u000a We measured the minimum transient change of length of a bimanually hand-held bar that could be detected. A bimanual haptic\\u000a interface was used to haptically render the bar in a static condition and two dynamic conditions involving discrete movements.\\u000a The detection thresholds were much lower in the static ( 10 mm). This finding suggests\\u000a that our proprioceptive acuity markedly decreases

Gabriel Baud-Bovy; Valentina Squeri; Vittorio Sanguineti

2010-01-01

63

High-energy above-threshold detachment from negative ions  

SciTech Connect

Above-threshold detachment of electrons from negative ions by an elliptically polarized laser field is analyzed within the strong-field approximation. The low-energy part of the spectrum, that is, its structure and its apparent cutoff, strongly depends on the orbital quantum number l of the initial ground state. The high-energy part is characterized by the usual extended plateau caused by rescattering, which is essentially independent of the ground state. The potential that the returning electron experiences during rescattering is modeled by the sum of a polarization potential and a static potential. This rescattering potential does not have much effect on the shape of the plateau, but it does on its height. For H{sup -} (l=0), the yield of rescattered electrons is five orders of magnitude below the direct electrons, while for I{sup -} (l=1) the yields only differ by a factor of 40. We also analyze the dependence of the angle-resolved energy spectrum on the ellipticity of the laser field and confirm general symmetry properties. An angle-integrated elliptic dichroism parameter is introduced and analyzed.

Gazibegovic-Busuladzic, A.; Milosevic, D.B. [Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, 71000 Sarajevo (Bosnia and Herzegowina); Becker, W. [Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin (Germany)

2004-11-01

64

Detection thresholds for amplitude modulations of tones in budgerigar, rabbit, and human.  

PubMed

Envelope fluctuations of complex sounds carry information that is -essential for many types of discrimination and for detection in noise. To study the neural representation of envelope information and mechanisms for processing of this temporal aspect of sounds, it is useful to identify an animal model that can -sensitively detect amplitude modulations (AM). Low modulation frequencies, which dominate speech sounds, are of particular interest. Yet, most animal -models studied previously are relatively insensitive to AM at low modulation -frequencies. Rabbits have high thresholds for low-frequency modulations, -especially for tone carriers. Rhesus macaques are less sensitive than humans to low-frequency -modulations of wideband noise (O'Conner et al. Hear Res 277, 37-43, 2011). Rats and -chinchilla also have higher thresholds than humans for amplitude -modulations of noise (Kelly et al. J Comp Psychol 120, 98-105, 2006; Henderson et al. J Acoust Soc Am 75, -1177-1183, 1984). In contrast, the budgerigar has thresholds for AM detection of wideband noise similar to those of human listeners at low -modulation frequencies (Dooling and Searcy. Percept Psychophys 46, 65-71, 1981). A -one-interval, two-alternative operant conditioning procedure was used to estimate AM -detection thresholds for 4-kHz tone carriers at low modulation -frequencies (4-256 Hz). Budgerigar thresholds are comparable to those of human subjects in a comparable task. Implications of these comparative results for temporal coding of complex sounds are discussed. Comparative results for masked AM detection are also presented. PMID:23716245

Carney, Laurel H; Ketterer, Angela D; Abrams, Kristina S; Schwarz, Douglas M; Idrobo, Fabio

2013-01-01

65

Efficient time-series detection of the strong stochasticity threshold in Fermi-Pasta-Ulam oscillator lattices.  

PubMed

In this work we study the possibility of detecting the so-called strong stochasticity threshold (i.e., the transition between weak and strong chaos as the energy density of the system is increased) in anharmonic oscillator chains by means of the 0-1 test for chaos. We compare the result of the aforementioned methodology with the scaling behavior of the largest Lyapunov exponent computed by means of tangent space dynamics, which has, so far, been the most reliable method available to detect the strong stochasticity threshold. We find that indeed the 0-1 test can perform the detection in the range of energy density values studied. Furthermore, we determined that conventional nonlinear time series analysis methods fail to properly compute the largest Lyapounov exponent even for very large data sets, whereas the computational effort of the 0-1 test remains the same in the whole range of values of the energy density considered with moderate size time series. Therefore, our results show that, for a qualitative probing of phase space, the 0-1 test can be an effective tool if its limitations are properly taken into account. PMID:21405766

Romero-Bastida, M; Reyes-Martínez, Alan Yoshio

2011-01-31

66

Determination of Odor Detection Threshold in the G?ttingen Minipig  

PubMed Central

The aim of the study was to examine the ability of Göttingen minipigs to acquire an olfaction-based operant conditioning task and to determine the detection threshold for ethyl acetate and ethanol. We used an automated olfactometer developed for rodents to train and test 14 pigs. Odor sampling and reliable responding were obtained after three to fifteen 160-trial sessions. Successful transfer of the task from ethyl acetate to ethanol was achieved in 1–4 sessions. Detection threshold for ethyl acetate varied between 10?2% and 10?6% v/v and for ethanol between 0.1% and 5 × 10?6% v/v. The results provide evidence that minipigs can successfully acquire 2-odorant discrimination using a food-rewarded instrumental conditioning paradigm for testing olfactory function. This olfactory discrimination paradigm provides reliable measures of olfactory sensitivity and thereby enables detection of changes in olfaction in a porcine model of Alzheimer's disease currently being developed.

Holm, Ida E.; Herskin, Mette S.; Dagnaes-Hansen, Frederik; Johansen, Marianne G.; J?rgensen, Arne Lund; Ladewig, Jan

2010-01-01

67

Ion rotational distributions at near-threshold photoelectron energies  

SciTech Connect

Rotationally resolved photoelectron spectra can provide much insight into the underlying dynamics of molecular photoionization, one of the simplest of molecular fragmentation processes. With the recent development of zero-kinetic-energy (ZEKE) photoelectron spectroscopy based on pulsed-field ionization of very high Rydberg states, it is now possible to exploit the narrow bandwidth of laser radiation to achieve sub-wave-number resolution in ion rovibronic state distributions. The unprecedented resolution of this technique has led to a surge of experimental activity in molecular photoelectron spectroscopy. In this talk I will discuss results of our recent studies of such rotationally resolved photoelectron spectra at very-near threshold energies for single-photon ionization of the ground states of NO, CO, H{sub 2}O, H{sub 2}S, CH{sub 3}, and H{sub 2}CO by coherent radiation. The agreement between the calculated and measured photoelectron spectra is generally very encouraging. These studies will serve to highlight the rich dynamics of quantum-state specific studies of molecular photoionization and, where possible, provide a robust description of key spectral features of interest in related experimental studies.

McKoy, V.

1993-05-01

68

30 CFR 62.174 - Follow-up corrective measures when a standard threshold shift is detected.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Follow-up corrective measures when a standard threshold shift is detected. 62.174 ...OCCUPATIONAL NOISE EXPOSURE § 62.174 Follow-up corrective measures when a standard threshold shift is detected. The...

2013-07-01

69

The Emergence of HIV Transmitted Resistance in Botswana: "When Will the WHO Detection Threshold Be Exceeded?"  

PubMed Central

Background The Botswana antiretroviral program began in 2002 and currently treats 42,000 patients, with a goal of treating 85,000 by 2009. The World Health Organization (WHO) has begun to implement a surveillance system for detecting transmitted resistance that exceeds a threshold of 5%. However, the WHO has not determined when this threshold will be reached. Here we model the Botswana government's treatment plan and predict, to 2009, the likely stochastic evolution of transmitted resistance. Methods We developed a model of the stochastic evolution of drug-resistant strains and formulated a birth-death Master equation. We analyzed this equation to obtain an analytical solution of the probabilistic evolutionary trajectory for transmitted resistance, and used treatment and demographic data from Botswana. We determined the temporal dynamics of transmitted resistance as a function of: (i) the transmissibility (i.e., fitness) of the drug-resistant strains that may evolve and (ii) the rate of acquired resistance. Results Transmitted resistance in Botswana will be unlikely to exceed the WHO's threshold by 2009 even if the rate of acquired resistance is high and the strains that evolve are half as fit as the wild-type strains. However, we also found that transmission of drug-resistant strains in Botswana could increase to ?15% by 2009 if the drug-resistant strains that evolve are as fit as the wild-type strains. Conclusions Transmitted resistance will only be detected by the WHO (by 2009) if the strains that evolve are extremely fit and acquired resistance is high. Initially after a treatment program is begun a threshold lower than 5% should be used; and we advise that predictions should be made before setting a threshold. Our results indicate that it may be several years before the WHO's surveillance system is likely to detect transmitted resistance in other resource-poor countries that have significantly less ambitious treatment programs than Botswana.

Vardavas, Raffaele; Blower, Sally

2007-01-01

70

Vibrotactile detection thresholds for chest skin of amputees following targeted reinnervation surgery.  

PubMed

Recent advances in the design of prosthetic arms have helped upper limb amputees achieve greater levels of function. However, control of upper limb prostheses is limited by the lack of sensory feedback to the user. Targeted reinnervation, a novel surgical technique for amputees, offers the potential for returning this lost sensation. During targeted reinnervation surgery, truncated nerves are directed to reinnervate new muscle and skin sites. Contractions of reinnervated muscles generate electrical signals that are used to control prosthetic arms. In addition, stimulation of reinnervated skin is perceived on the missing limb. Vibration detection thresholds were measured at four frequencies on the reinnervated chest skin of three shoulder-level amputees following targeted reinnervation surgery. Thresholds were also measured on the contralateral chest and arm skin of these amputees, as well as on the chest and arm skin of a control population. Vibrations applied to reinnervated skin were perceived at various locations on the missing arm and hand. Thresholds for the reinnervated chest skin were generally within the range of values measured on the chests of the control population. For the two unilateral amputees, these thresholds were similar to measures on their contralateral chests, but greater than measures on their contralateral hands. Targeted reinnervation appears to result in near-normal vibration-detection ability with respect to the target tissue, suggesting the functional reinnervation of mechanoreceptors by the reinnervating afferents. The functional limb sensation following targeted reinnervation could be used to provide prosthesis users with a sense of touch. PMID:19059226

Schultz, Aimee E; Marasco, Paul D; Kuiken, Todd A

2008-11-21

71

Cloud Detection: The Impact of Optical Depth, Spectral Thresholds, FOV, and Averaging  

NASA Astrophysics Data System (ADS)

New satellite instruments, such as MODIS, GLI and AIRS, provide new capabilities in cloud detection. This poster addresses the impact of cloud optical depth on cloud detection using passive remote sensing instruments on a satellite or high-altitude aircraft platform. What is a cloud? The answer to that question is determined by the application. What is considered a cloud in some applications may be defined as clear in other applications. For example, detection of thin cirrus clouds is important for applications of infrared remote sensing of sea surface temperature, but of little concern for microwave remote sounding of atmospheric temperature. The MODIS cloud masks were designed to support various applications, but the optical depth limit of detection has not been defined. This paper defines MODIS cloud detection retrievals with lidar observations to estimate the optical depth limit of detection for these passive instruments. It also presents the dependence of cloud amount on selected thresholds and spatial averaging.

Ackerman, S. A.; Frey, R. A.; Eloranta, E.; Holz, R. E.

2005-12-01

72

Fast microcalcification detection in ultrasound images using image enhancement and threshold adjacency statistics  

NASA Astrophysics Data System (ADS)

The existence of microcalcifications (MCs) is an important marker of malignancy in breast cancer. In spite of the benefits in mass detection for dense breasts, ultrasonography is believed that it might not reliably detect MCs. For computer aided diagnosis systems, however, accurate detection of MCs has the possibility of improving the performance in both Breast Imaging-Reporting and Data System (BI-RADS) lexicon description for calcifications and malignancy classification. We propose a new efficient and effective method for MC detection using image enhancement and threshold adjacency statistics (TAS). The main idea of TAS is to threshold an image and to count the number of white pixels with a given number of adjacent white pixels. Our contribution is to adopt TAS features and apply image enhancement to facilitate MC detection in ultrasound images. We employed fuzzy logic, tophat filter, and texture filter to enhance images for MCs. Using a total of 591 images, the classification accuracy of the proposed method in MC detection showed 82.75%, which is comparable to that of Haralick texture features (81.38%). When combined, the performance was as high as 85.11%. In addition, our method also showed the ability in mass classification when combined with existing features. In conclusion, the proposed method exploiting image enhancement and TAS features has the potential to deal with MC detection in ultrasound images efficiently and extend to the real-time localization and visualization of MCs.

Cho, Baek Hwan; Chang, Chuho; Lee, Jong-Ha; Ko, Eun Young; Seong, Yeong Kyeong; Woo, Kyoung-Gu

2013-02-01

73

Effects of sodium depletion on detection thresholds for salty taste in rats  

Microsoft Academic Search

Previous studies, which have mostly focused on concentrated NaCl solution intake, have suggested sodium depletion may be accompanied with salt taste sensory changes. To further investigate whether the function of the salt taste system changes in different patterns for highly concentrated and diluted NaCl taste stimuli, the effects of sodium depletion on NaCl taste detection threshold in rats were examined.

Bo Lu; Jianqun Yan; Xuejuan Yang

2009-01-01

74

A threshold-based fall-detection algorithm using a bi-axial gyroscope sensor  

Microsoft Academic Search

A threshold-based algorithm, to distinguish between Activities of Daily Living (ADL) and falls is described. A gyroscope based fall-detection sensor array is used. Using simulated-falls performed by young volunteers under supervised conditions onto crash mats and ADL performed by elderly subjects, the ability to discriminate between falls and ADL was achieved using a bi-axial gyroscope sensor mounted on the trunk,

A. K. Bourke; G. M. Lyons

2008-01-01

75

Detection of visual-field deterioration by Glaucoma Progression Analysis and Threshold Noiseless Trend programs  

Microsoft Academic Search

Background:To compare the ability of Glaucoma Progression Analysis (GPA) and Threshold Noiseless Trend (TNT) programs to detect visual-field deterioration.Methods:Patients with open-angle glaucoma followed for a minimum of 2 years and a minimum of seven reliable visual fields were included. Progression was assessed subjectively by four masked glaucoma experts, and compared with GPA and TNT results. Each case was judged to

V T Diaz-Aleman; A Anton; M Gonzalez de la Rosa; Z K Johnson; S McLeod; A Azuara-Blanco

2009-01-01

76

Thresholds of Passive Microwave Snowfall Detection Determined Using A-Train Observations  

NASA Astrophysics Data System (ADS)

In this study we explore a database of CloudSat+AMSU-B coincident overpasses to determine the minimum threshold of passive microwave detection of snowfall using the high-frequency channels available on GMI. Using the Advanced Infrared Sounder (AIRS) temperature and water vapor profiles along with a surface emissivity database developed from AMSU-B and MHS observations, clear-sky radiances are simulated and compared to AMSU-B observed radiances for all profiles with a maximum temperature less than 271 K. The ability of a scattering signal (observed brightness tempertaure colder than clear-sky brightness temperature by a threshold T) to detect snowfall (CloudSat reflectivity greater than threshold Z) is quantified using the Heidke Skill Score. The 183+/-1 and 183+/-3 GHz channels have the highest skill scores, while those channels that are sensitive to the surface (89, 150 and 183+/-7 GHz) have zero or even negative skill (depending on Z and T), implying that an emission signal (presumably from cloud water) is as good or better for detecting precipitation than a scattering signal. These results emphasize the need for proper characterization of surface emissivity and adequate representation of cloud water in cold season precipitation profiles that form the databases used for Bayesian retrievals from GMI and other GPM constellation radiometers.

Munchak, S. J.; Skofronick Jackson, G.; Johnson, B. T.

2011-12-01

77

Fine-grained emotion detection in suicide notes: a thresholding approach to multi-label classification.  

PubMed

We present a system to automatically identify emotion-carrying sentences in suicide notes and to detect the specific fine-grained emotion conveyed. With this system, we competed in Track 2 of the 2011 Medical NLP Challenge,14 where the task was to distinguish between fifteen emotion labels, from guilt, sorrow, and hopelessness to hopefulness and happiness.Since a sentence can be annotated with multiple emotions, we designed a thresholding approach that enables assigning multiple labels to a single instance. We rely on the probability estimates returned by an SVM classifier and experimentally set thresholds on these probabilities. Emotion labels are assigned only if their probability exceeds a certain threshold and if the probability of the sentence being emotion-free is low enough. We show the advantages of this thresholding approach by comparing it to a naïve system that assigns only the most probable label to each test sentence, and to a system trained on emotion-carrying sentences only. PMID:22879761

Luyckx, Kim; Vaassen, Frederik; Peersman, Claudia; Daelemans, Walter

2012-01-30

78

A dynamic thresholds scheme for contaminant event detection in water distribution systems.  

PubMed

In this study, a dynamic thresholds scheme is developed and demonstrated for contamination event detection in water distribution systems. The developed methodology is based on a recently published article of the authors (Perelman et al., 2012). Event detection in water supply systems is aimed at disclosing abnormal hydraulic or water quality events by exploring the time series behavior of routine hydraulic (e.g., flow, pressure) and water quality measurements (e.g., residual chlorine, pH, turbidity). While event detection raises alerts to the possibility of an event occurrence, it does not relate to origins, thus an event may be hydraulically-driven, as a consequence of problems like sudden leakages or pump/pipe malfunctions. Most events, however, are related to deliberate, accidental, or natural contamination intrusions. The developed methodology herein is based on off-line and on-line stages. During the off-line stage, a genetic algorithm (GA) is utilized for tuning five decision variables: positive and negative filters, positive and negative dynamic thresholds, and window size. During the on-line stage, a recursively Bayes' rule is invoked, employing the five decision variables, for real time on-line event detection. Using the same database, the proposed methodology is compared to Perelman et al. (2012), showing considerably improved detection ability. Metadata and the computer code are provided as Supplementary material. PMID:23384516

Arad, Jonathan; Housh, Mashor; Perelman, Lina; Ostfeld, Avi

2013-01-23

79

Electrical microstimulation thresholds for behavioral detection and saccades in monkey frontal eye fields  

PubMed Central

The frontal eye field (FEF) is involved in the transformation of visual signals into saccadic eye movements. Although it is often considered an oculomotor structure, several lines of evidence suggest that the FEF also contributes to visual perception and attention. To better understand the range of behaviors to which the FEF can contribute, we tested whether monkeys could detect activation of their FEF by electrical microstimulation with currents below those that cause eye movements. We found that stimulation of FEF neurons could almost always be detected at levels below those needed to generate saccades and that the electrical current needed for detection was highly correlated with that needed to generate a saccade. This relationship between detection and saccade thresholds can be explained if FEF neurons represent preparation to make particular saccades and subjects can be aware of such preparations without acting on them when the representation is not strong.

Murphey, Dona K.; Maunsell, John H. R.

2008-01-01

80

Seismicity and detection/location threshold in the southern Great Basin seismic network  

USGS Publications Warehouse

A spatially varying model of the detection/location capabilities of the Southern Great Basin seismic network (SGBSN) has been derived that is based on simple empirical relations and statistics. This permits use of almost all the catalog data gathered; instead of ignoring data that are below the threshold of completeness, a spatially varying threshold model is developed so that subregions having lower completeness levels than the network as a whole can be outlined and the completeness level of each sub-region determined. The predominantly aseismic regions located include the area west of the Death Valley/Furnace Creek fault system and an almost complete absence of events at Yucca Mountain. -from Author

Gomberg, J.

1991-01-01

81

Information transmission and detection thresholds in the vestibular nuclei: single neurons vs. population encoding  

PubMed Central

Understanding how sensory neurons transmit information about relevant stimuli remains a major goal in neuroscience. Of particular relevance are the roles of neural variability and spike timing in neural coding. Peripheral vestibular afferents display differential variability that is correlated with the importance of spike timing; regular afferents display little variability and use a timing code to transmit information about sensory input. Irregular afferents, conversely, display greater variability and instead use a rate code. We studied how central neurons within the vestibular nuclei integrate information from both afferent classes by recording from a group of neurons termed vestibular only (VO) that are known to make contributions to vestibulospinal reflexes and project to higher-order centers. We found that, although individual central neurons had sensitivities that were greater than or equal to those of individual afferents, they transmitted less information. In addition, their velocity detection thresholds were significantly greater than those of individual afferents. This is because VO neurons display greater variability, which is detrimental to information transmission and signal detection. Combining activities from multiple VO neurons increased information transmission. However, the information rates were still much lower than those of equivalent afferent populations. Furthermore, combining responses from multiple VO neurons led to lower velocity detection threshold values approaching those measured from behavior (?2.5 vs. 0.5–1°/s). Our results suggest that the detailed time course of vestibular stimuli encoded by afferents is not transmitted by VO neurons. Instead, they suggest that higher vestibular pathways must integrate information from central vestibular neuron populations to give rise to behaviorally observed detection thresholds.

Massot, Corentin; Chacron, Maurice J.

2011-01-01

82

Influence of the mean luminance on the detection threshold for red-green chromatic gratings  

NASA Astrophysics Data System (ADS)

The objective of the study was to examine the influence of the mean luminance level on the detection thresholds for red-green chromatic gratings of three different spatial frequencies. Data for chromatic sinusoidal gratings with higher mean luminance levels (within the photopic level) than those ones used in previous works were reported. The study analyzed the transition luminance between the DeVries- Rose law and the Weber law regions, and considered the validity of the constant-flux hypothesis for the three spatial frequencies tested. The results suggest that the 'flux' would not be a critical factor in the processing of chromatic gratings in the low spatial frequency range.

Nieves Gomez, Juan L.; Valero, E.; Hernandez-Andres, Javier; Garcia, Jose A.; Romero, Javier

2002-06-01

83

Effects of threshold displacement energy on defect production by displacement cascades in ?, ? and ?-LiAlO2  

NASA Astrophysics Data System (ADS)

Threshold displacement energy evaluation and a series of displacement cascade simulations in ?, ?, and ?-LiAlO2 were performed using molecular dynamics. Threshold displacement energy evaluations indicated that higher absolute ionic charge values and larger densities both increase threshold displacement energy. The displacement cascade simulations suggest that the influence of different crystal structures on the number of interstitial atoms generated in a displacement cascade is explainable almost entirely by the difference of the threshold displacement energy.

Tsuchihira, H.; Oda, T.; Tanaka, S.

2013-11-01

84

Determination of bond dissociation energies by threshold ion-pair production spectroscopy: An improved D0(HCl)  

Microsoft Academic Search

A recently developed form of threshold ionization spectroscopy has been used to determine the bond energy for HCl to spectroscopic accuracy (±0.8 cm?1). This method is based on excitation to highly vibrationally excited ion-pair states using single-photon transitions from the ground state of HCl. These metastable Rydberg-like states were selectively detected using electricfield induced dissociation. By systematically varying the electric

J. D. D. Martin; J. W. Hepburn

1998-01-01

85

Determination of bond dissociation energies by threshold ion-pair production spectroscopy: An improved D0(HCl)  

Microsoft Academic Search

A recently developed form of threshold ionization spectroscopy has been used to determine the bond energy for HCl to spectroscopic accuracy (+\\/-0.8 cm-1). This method is based on excitation to highly vibrationally excited ion-pair states using single-photon transitions from the ground state of HCl. These metastable Rydberg-like states were selectively detected using electricfield induced dissociation. By systematically varying the electric

J. D. D. Martin; J. W. Hepburn

1998-01-01

86

Detecting modulated signals in modulated noise: (II) neural thresholds in the songbird forebrain.  

PubMed

Sounds in the real world fluctuate in amplitude. The vertebrate auditory system exploits patterns of amplitude fluctuations to improve signal detection in noise. One experimental paradigm demonstrating these general effects has been used in psychophysical studies of 'comodulation detection difference' (CDD). The CDD effect refers to the fact that thresholds for detecting a modulated, narrowband noise signal are lower when the envelopes of flanking bands of modulated noise are comodulated with each other, but fluctuate independently of the signal compared with conditions in which the envelopes of the signal and flanking bands are all comodulated. Here, we report results from a study of the neural correlates of CDD in European starlings (Sturnus vulgaris). We manipulated: (i) the envelope correlations between a narrowband noise signal and a masker comprised of six flanking bands of noise; (ii) the signal onset delay relative to masker onset; (iii) signal duration; and (iv) masker spectrum level. Masked detection thresholds were determined from neural responses using signal detection theory. Across conditions, the magnitude of neural CDD ranged between 2 and 8 dB, which is similar to that reported in a companion psychophysical study of starlings [U. Langemann & G.M. Klump (2007) Eur. J. Neurosci., 26, 1969-1978]. We found little evidence to suggest that neural CDD resulted from the across-channel processing of auditory grouping cues related to common envelope fluctuations and synchronous onsets between the signal and flanking bands. We discuss a within-channel model of peripheral processing that explains many of our results. PMID:17897401

Bee, Mark A; Buschermöhle, Michael; Klump, Georg M

2007-10-01

87

Electron-nuclear energy sharing in above-threshold multiphoton dissociative ionization of H2.  

PubMed

We report experimental observation of the energy sharing between electron and nuclei in above-threshold multiphoton dissociative ionization of H2 by strong laser fields. The absorbed photon energy is shared between the ejected electron and nuclei in a correlated fashion, resulting in multiple diagonal lines in their joint energy spectrum governed by the energy conservation of all fragment particles. PMID:23889391

Wu, J; Kunitski, M; Pitzer, M; Trinter, F; Schmidt, L Ph H; Jahnke, T; Magrakvelidze, M; Madsen, C B; Madsen, L B; Thumm, U; Dörner, R

2013-07-09

88

Electron-Nuclear Energy Sharing in Above-Threshold Multiphoton Dissociative Ionization of H2  

NASA Astrophysics Data System (ADS)

We report experimental observation of the energy sharing between electron and nuclei in above-threshold multiphoton dissociative ionization of H2 by strong laser fields. The absorbed photon energy is shared between the ejected electron and nuclei in a correlated fashion, resulting in multiple diagonal lines in their joint energy spectrum governed by the energy conservation of all fragment particles.

Wu, J.; Kunitski, M.; Pitzer, M.; Trinter, F.; Schmidt, L. Ph. H.; Jahnke, T.; Magrakvelidze, M.; Madsen, C. B.; Madsen, L. B.; Thumm, U.; Dörner, R.

2013-07-01

89

Influence of ion beam energy on SEGR failure thresholds of vertical power MOSFETs  

SciTech Connect

For the first time, experimental observations and numerical simulations show that the impact energy of the test ion influences the single-event gate rupture (SEGR) failure thresholds of vertical power MOSFETs. Current testing methodology may produce false hardness assurance.

Titus, J.L. [Naval Surface Warfare Center, Crane, IN (United States); Wheatley, C.F. [Wheatley (C.F.), Drums, PA (United States); Allenspach, M.; Schrimpf, R.D.; Brews, J.R.; Galloway, K.F. [Univ. of Arizona, Tucson, AZ (United States); Burton, D.I. [Harris Semiconductor, Mountaintop, PA (United States); Pease, R.L. [RLP Research, Inc., Albuquerque, NM (United States)

1996-12-01

90

Development and the role of internal noise in detection and discrimination thresholds with narrow band stimuli  

PubMed Central

The experiments reported here examine the role of internal noise in the detection of a tone in narrow band noise and intensity discrimination for narrow band stimuli in school-aged children as compared to adults. Experiment 1 used 20-Hz wide bands of Gaussian and low-fluctuation noise centered at 500 Hz to assess the role of stimulus fluctuation in detection of a 500-Hz pure tone. Additional conditions tested whether performance was based on level and/or level-independent cues. Children’s thresholds were elevated with respect to adults, and whereas adults benefited from the reduced fluctuation of low-fluctuation noise, children did not. Results from both groups were consistent with the use of a level cue. Experiment 2 estimated intensity increment thresholds for a narrow band Gaussian noise or a pure tone, either with or without a presentation-by-presentation level rove, an additional source of level variability. Stimulus variability was found to have a larger effect on performance of adults as compared to children, a rather counterintuitive finding if one thinks of children as more prone to informational masking introduced by stimulus variability. Both tone-in-noise and intensity discrimination data were consistent with the hypothesis that children’s performance is limited by greater levels of internal noise.

Buss, Emily; Hall, Joseph W.; Grose, John H.

2007-01-01

91

MOA-2010-BLG-311: A Planetary Candidate below the Threshold of Reliable Detection  

NASA Astrophysics Data System (ADS)

We analyze MOA-2010-BLG-311, a high magnification (A max > 600) microlensing event with complete data coverage over the peak, making it very sensitive to planetary signals. We fit this event with both a point lens and a two-body lens model and find that the two-body lens model is a better fit but with only ??2 ~ 80. The preferred mass ratio between the lens star and its companion is q = 10-3.7 ± 0.1, placing the candidate companion in the planetary regime. Despite the formal significance of the planet, we show that because of systematics in the data the evidence for a planetary companion to the lens is too tenuous to claim a secure detection. When combined with analyses of other high-magnification events, this event helps empirically define the threshold for reliable planet detection in high-magnification events, which remains an open question.

Yee, J. C.; Hung, L.-W.; Bond, I. A.; Allen, W.; Monard, L. A. G.; Albrow, M. D.; Fouqué, P.; Dominik, M.; Tsapras, Y.; Udalski, A.; Gould, A.; Zellem, R.; Bos, M.; Christie, G. W.; DePoy, D. L.; Dong, Subo; Drummond, J.; Gaudi, B. S.; Gorbikov, E.; Han, C.; Kaspi, S.; Klein, N.; Lee, C.-U.; Maoz, D.; McCormick, J.; Moorhouse, D.; Natusch, T.; Nola, M.; Park, B.-G.; Pogge, R. W.; Polishook, D.; Shporer, A.; Shvartzvald, Y.; Skowron, J.; Thornley, G.; The ?FUN Collaboration; Abe, F.; Bennett, D. P.; Botzler, C. S.; Chote, P.; Freeman, M.; Fukui, A.; Furusawa, K.; Harris, P.; Itow, Y.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Miyake, N.; Ohnishi, K.; Rattenbury, N. J.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Sweatman, W. L.; Tristram, P. J.; Wada, K.; Yock, P. C. M.; The MOA Collaboration; Szyma?ski, M. K.; Soszy?ski, I.; Kubiak, M.; Poleski, R.; Ulaczyk, K.; Pietrzy?ski, G.; Wyrzykowski, ?.; The OGLE Collaboration; Bachelet, E.; Batista, V.; Beatty, T. G.; Beaulieu, J.-P.; Bennett, C. S.; Bowens-Rubin, R.; Brillant, S.; Caldwell, J. A. R.; Cassan, A.; Cole, A. A.; Corrales, E.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Greenhill, J.; Henderson, C. B.; Kubas, D.; Marquette, J.-B.; Martin, R.; Menzies, J. W.; Shappee, B.; Williams, A.; Wouters, D.; van Saders, J.; Zub, M.; The PLANET Collaboration; Street, R. A.; Horne, K.; Bramich, D. M.; Steele, I. A.; The RoboNet Collaboration; Alsubai, K. A.; Bozza, V.; Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Finet, F.; Gerner, T.; Hardis, S.; Harpsøe, K.; Hessman, F. V.; Hinse, T. C.; Hundertmark, M.; Jørgensen, U. G.; Kains, N.; Kerins, E.; Liebig, C.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Proft, S.; Rahvar, S.; Ricci, D.; Sahu, K. C.; Scarpetta, G.; Schäfer, S.; Schönebeck, F.; Snodgrass, C.; Southworth, J.; Surdej, J.; Wambsganss, J.; MiNDSTEp Consortium, The

2013-05-01

92

Research on detectable threshold of double MCP ultraviolet image intensifier tube  

NASA Astrophysics Data System (ADS)

In order to research the influence of the quantity of the Micro-Channel Plates (MCP) on the detectable threshold of the ultraviolet image intensifier tube, the wide spectrum image intensifier gain tester produced by Nanjing University of Science and Technology is employed to test the relation curves between self-made one single MCP ultraviolet image intensifier tube, two double MCP ultraviolet image intensifier tubes, and photocathode incidence radiation illumination respectively. With reference to the 3rd-generation low-light image intensifier failure theory, if the radiation gain of the ultraviolet image intensifier tube is defined as 1,000cd/m2, the tube will lose the effect of image intensification, when the corresponding photocathode incidence radiation illumination will be the minimum detectable threshold. Viewed from the test results, the minimum detectable threshold of the single MCP ultraviolet image intensifier tube is 3.0×10-6 W/m2, with the radiance gain linear interval between 3.0×10-6 W/m2 ?4.6×10-5 W/m2; and that of the double MCP ultraviolet image intensifier tubes is 4×10-7 W/m2, with the radiance gain linear interval between 4.0×10-7 W/m2 ?2.0×10-5 W/m2. The test results were analyzed on the basis of the MCP self-saturation effect, concluding that the saturation current density of the single-unit MCP is a fixed , but there may be certain difference among the saturation current density of different MCPs due to different materials and manufacturing processes. The test results show that the maximum of the radiation gain linear interval of the three ultraviolet image intensifier tubes are at the magnitude of 10-5 W/m2, and the non-significant differences also verified the theory. In the double MCP ultraviolet image intensifier tubes, the photocathode-produced photocurrent is multiplied in passing the first MCP and then reaches the second MCP, so the second MCP will reach the state of current saturation earlier than the first MCP, making the minimum detectable threshold of the double MCP ultraviolet image intensifier tubes is lower than that of the single ultraviolet image intensifier tube by one order of magnitude, with the linear gain interval increasing by one magnitude, and the absolute of the corresponding radiation gain of the same radiation illumination within the linear gain interval increasing by 10 times, verifying that the double MCPs can detect much lower and weaker ultraviolet radiation and realize the high gain theory. The research results has certain guiding effect towards the promotion and application of the double ultraviolet image intensifier tubes, and has great significance on enhancing the high ultraviolet radiation detection and imaging technology.

Cheng, Hong-chang; Duanmu, Qing-duo; Shi, Feng; Shi, Hong-li; Liu, Hui; Feng, Liu; He, Ying-ping; Hou, Zhi-peng; Yan, Lei; Ren, Ling

2013-08-01

93

Threshold effects in strong-field ionization: Energy shifts and Rydberg structures  

NASA Astrophysics Data System (ADS)

The behavior of strong-field ionization rates of neutral atoms in the vicinity of multiphoton ionization thresholds is analyzed using formal collision theory. Our approach, which accounts nonperturbatively for effects of an intense laser field, shows that the ionization rates have a nearly constant behavior below and above each multiphoton threshold and that between such thresholds there are an apparently finite number of rapid oscillations due to resonances with laser-field-modified Rydberg states. This pattern is typical for any atomic target, as we illustrate specifically for hydrogen and neon atoms. The flat behavior of the ionization yield near multiphoton thresholds gives the appearance of an energy shift of the ionization thresholds, which have been postulated in a number of recent studies concerning diverse aspects of above-threshold ionization and high-harmonic generation of atoms. The flat behaviors of the rates near threshold exhibit only a rather weak dependence on the laser-field intensity. Other aspects of the near-threshold behavior of ionization rates and their dependence on the laser-field parameters are also discussed.

Krajewska, K.; Fabrikant, I. I.; Starace, A. F.

2012-11-01

94

A quick method for computing approximate thresholds for quantitative trait loci detection.  

PubMed Central

This article proposes a quick method for computing approximate threshold levels that control the genome-wise type I error rate of tests for quantitative trait locus (QTL) detection in interval mapping (IM) and composite interval mapping (CIM). The procedure is completely general, allowing any population structure to be handled, e.g., BC(1), advanced backcross, F(2), and advanced intercross lines. Its main advantage is applicability in complex situations where no closed form approximate thresholds are available. Extensive simulations demonstrate that the method works well over a range of situations. Moreover, the method is computationally inexpensive and may thus be used as an alternative to permutation procedures. For given values of the likelihood-ratio (LR)-profile, computations involve just a few seconds on a Pentium PC. Computations are simple to perform, requiring only the values of the LR statistics (or LOD scores) of a QTL scan across the genome as input. For CIM, the window size and the position of cofactors are also needed. For the approximation to work well, it is suggested that scans be performed with a relatively small step size between 1 and 2 cM.

Piepho, H P

2001-01-01

95

Adaptive optics for reduced threshold energy in femtosecond laser induced optical breakdown in water based eye model  

NASA Astrophysics Data System (ADS)

In ophthalmic microsurgery tissue dissection is achieved using femtosecond laser pulses to create an optical breakdown. For vitreo-retinal applications the irradiance distribution in the focal volume is distorted by the anterior components of the eye causing a raised threshold energy for breakdown. In this work, an adaptive optics system enables spatial beam shaping for compensation of aberrations and investigation of wave front influence on optical breakdown. An eye model was designed to allow for aberration correction as well as detection of optical breakdown. The eye model consists of an achromatic lens for modeling the eye's refractive power, a water chamber for modeling the tissue properties, and a PTFE sample for modeling the retina's scattering properties. Aberration correction was performed using a deformable mirror in combination with a Hartmann-Shack-sensor. The influence of an adaptive optics aberration correction on the pulse energy required for photodisruption was investigated using transmission measurements for determination of the breakdown threshold and video imaging of the focal region for study of the gas bubble dynamics. The threshold energy is considerably reduced when correcting for the aberrations of the system and the model eye. Also, a raise in irradiance at constant pulse energy was shown for the aberration corrected case. The reduced pulse energy lowers the potential risk of collateral damage which is especially important for retinal safety. This offers new possibilities for vitreo-retinal surgery using femtosecond laser pulses.

Hansen, Anja; Krueger, Alexander; Ripken, Tammo

2013-03-01

96

Changes to cold detection and pain thresholds following low and high frequency transcranial magnetic stimulation of the motor cortex  

Microsoft Academic Search

There is some evidence that repetitive transcranial magnetic stimulation (rTMS) can alleviate the experience of chronic pain. The mechanisms by which rTMS may induce pain relief, however, are unknown. The present study examined whether a session of rTMS would produce sensory threshold changes in healthy individuals. Detection and pain thresholds for cold sensations were compared following low frequency (1Hz) (Experiment

Jeff Summers; Sama Johnson; Saxby Pridmore; Gajinder Oberoi

2004-01-01

97

Bayesian decision threshold, detection limit and confidence limits in ionising-radiation measurement.  

PubMed

Based on Bayesian statistics and the Bayesian theory of measurement uncertainty, characteristic limits such as the decision threshold, detection limit and limits of a confidence interval can be calculated taking into account all sources of uncertainty. This approach consists of the complete evaluation of a measurement according to the ISO Guide to the Expression of Uncertainty in Measurement (GUM) and the successive determination of the characteristic limits by using the standard uncertainty obtained from the evaluation. This procedure is elaborated here for several particular models of evaluation. It is, however, so general that it allows for a large variety of applications to similar measurements. It is proposed for the revision of those parts of DIN 25482 and ISO 11929 that are still based on conventional statistics and, therefore, do not allow to take completely into account all the components of measurement uncertainty in the calculation of the characteristic limits. PMID:16868015

Weise, K; Hübel, K; Rose, E; Schläger, M; Schrammel, D; Täschner, M; Michel, R

2006-07-25

98

Validation of efficiency tracing and zero detection threshold techniques using liquid scintillation analyser TriCarb.  

PubMed

Efficiency tracing with unquenched 14C and zero detection threshold with unquenched 3H as tracers are practical and simple techniques which have been implemented to quantify the activity of various beta emitters using liquid scintillation analyser. These techniques are used to study the influence of quench level on activity quantification and the activity levels up to which these techniques are applicable. The results indicate that, for an activity level of 166.67 Bq, both the techniques are in good agreement with the reference activity with a relative discrepancy of ?4.6 %. The relative discrepancy of ~10 % is observed for extreme quench values of ~111. For all the radionuclides with the activity level of 1.67 Bq, the uncertainty in activity quantification raises to ~8 % and for the activity level from 8.33 to 100 Bq, the uncertainty reduces to 1 %. PMID:21196460

Reddy, P J; Bhade, S P D; Babu, D A R; Sharma, D N

2010-12-31

99

Energy dependence of electron damage and displacement threshold energy in 6H silicon carbide  

SciTech Connect

This paper reports on the frequency response of silicon carbide (SiC) light-emitting diodes that have been used to measure the energy dependence of displacement damage produced in 6H SiC by energetic electrons. The minimum electron energy required to produce displacement damage was determined to be 108 {plus minus} 7 keV, corresponding to an atomic displacement threshold energy, E{sub d}, of 21.8 {plus minus} 1.5 eV for the carbon atom. No evidence was seen of persistent damage due to displacement of silicon atoms. For electrons of energies greater than 0.5 MeV, the damage constant for lifetime degradation in SiC is lower than that for GaAs by more than three orders of magnitude, indicating a greatly superior resistance of SiC to displacement damage in most radiation environments.

Barry, A.L. (Communication Research Center, Ottawa (CA)); Lehmann, B.; Fritsch, D.; Braunig, D. (Hahn-Meitner-Inst. Berlin GmbH, Berlin (DE))

1991-12-01

100

Threshold-based system for noise detection in multilead ECG recordings.  

PubMed

This paper presents a system for detection of the most common noise types seen on the electrocardiogram (ECG) in order to evaluate whether an episode from 12-lead ECG is reliable for diagnosis. It implements criteria for estimation of the noise corruption level in specific frequency bands, aiming to identify the main sources of ECG quality disruption, such as missing signal or limited dynamics of the QRS components above 4 Hz; presence of high amplitude and steep artifacts seen above 1 Hz; baseline drift estimated at frequencies below 1 Hz; power-line interference in a band ±2 Hz around its central frequency; high-frequency and electromyographic noises above 20 Hz. All noise tests are designed to process the ECG series in the time domain, including 13 adjustable thresholds for amplitude and slope criteria which are evaluated in adjustable time intervals, as well as number of leads. The system allows flexible extension toward application-specific requirements for the noise levels in acceptable quality ECGs. Training of different thresholds' settings to determine different positive noise detection rates is performed with the annotated set of 1000 ECGs from the PhysioNet database created for the Computing in Cardiology Challenge 2011. Two implementations are highlighted on the receiver operating characteristic (area 0.968) to fit to different applications. The implementation with high sensitivity (Se = 98.7%, Sp = 80.9%) appears as a reliable alarm when there are any incidental problems with the ECG acquisition, while the implementation with high specificity (Sp = 97.8%, Se = 81.8%) is less susceptible to transient problems but rather validates noisy ECGs with acceptable quality during a small portion of the recording. PMID:22902891

Jekova, Irena; Krasteva, Vessela; Christov, Ivaylo; Abächerli, Roger

2012-08-17

101

Evaluation of a change detection methodology by means of binary thresholding algorithms and informational fusion processes.  

PubMed

Landcover is subject to continuous changes on a wide variety of temporal and spatial scales. Those changes produce significant effects in human and natural activities. Maintaining an updated spatial database with the occurred changes allows a better monitoring of the Earth's resources and management of the environment. Change detection (CD) techniques using images from different sensors, such as satellite imagery, aerial photographs, etc., have proven to be suitable and secure data sources from which updated information can be extracted efficiently, so that changes can also be inventoried and monitored. In this paper, a multisource CD methodology for multiresolution datasets is applied. First, different change indices are processed, then different thresholding algorithms for change/no_change are applied to these indices in order to better estimate the statistical parameters of these categories, finally the indices are integrated into a change detection multisource fusion process, which allows generating a single CD result from several combination of indices. This methodology has been applied to datasets with different spectral and spatial resolution properties. Then, the obtained results are evaluated by means of a quality control analysis, as well as with complementary graphical representations. The suggested methodology has also been proved efficiently for identifying the change detection index with the higher contribution. PMID:22737023

Molina, Iñigo; Martinez, Estibaliz; Arquero, Agueda; Pajares, Gonzalo; Sanchez, Javier

2012-03-13

102

Milagro: A low energy threshold extensive air shower array  

SciTech Connect

Observations of high-energy gamma rays from astronomical sources have revolutionized our view of the cosmos. Gamma rays with energies up to {approximately}10 GeV can be observed directly with space-based instruments. Above 100 GeV the low flux of gamma rays requires one to utilize ground-based instruments. Milagro is a new type of gamma-ray detector based on water Cerenkov technology. This new design will enable to continuously observe the entire overhead sky, and be sensitive to cosmic rays with energies above {approximately}250 GeV. These attributes make Milagro an ideal detector for the study of high-energy transient phenomenon.

Sinnis, C.

1994-12-31

103

Modification of screening immunoassays to detect sub-threshold concentrations of cocaine, cannabinoids, and opiates in urine: use for detecting maternal and neonatal drug exposures.  

PubMed

Testing for drugs of abuse in urine is commonplace in emergency departments and neonatal units. However, the clinical sensitivity of immunochemical screening methods is limited by the threshold concentrations used to distinguish between positive and negative specimens. Immunochemical screening methods for cocaine metabolite (benzoylecgonine), cannabinoids, and opiates in urine were recalibrated to detect drugs at lower threshold concentrations. The precision and linearity of the signals at the modified thresholds were verified by diluting drug-positive urine specimens to concentrations below the conventional cutoff concentration and measuring the rate signals in triplicate. To assess the clinical performance of the modified methods, specimens that tested negative using the unmodified assays were re-screened at the lower threshold, and specimens that re-screened positive were submitted for gas chromatographic/mass spectrometric (GC/MS) confirmation. Reproducibility of sub-threshold measurements was comparable to the unmodified assays, and rate separations between successive dilutions were sufficient to give semi-quantitative results. Using the lower thresholds, drugs were detected in 4-5% of the subjects that had screened negative at the conventional threshold concentration. GC/MS analysis confirmed the presence of cannabinoids and cocaine metabolite in 74% and 84%, respectively, of urine specimens that re-screened positive. Morphine, codeine, hydromorphone, or hydrocodone was detected by GC/MS analysis in 31% of opiate-positive re-screens. PMID:10678589

Hattab, E M; Goldberger, B A; Johannsen, L M; Kindland, P W; Ticino, F; Chronister, C W; Bertholf, R L

2000-01-01

104

Development Of An Electronic Nose For Environmental Monitoring: Detection Of Specific Environmentally Important Gases At Their Odor Detection Threshold Concentration  

NASA Astrophysics Data System (ADS)

The use of a sensor array is demonstrated to be an effective approach to evaluate hazardous odor (or gas) emissions from industrial sites1. Therefore the possibility to use electronic noses for the prolonged survey of odor emissions from industrial sites is of particular interest for environmental monitoring purposes2. At the Olfactometric Laboratory of the Politecnico di Milano, in collaboration with Sacmi Group, Imola, an innovative electronic nose for the continuous monitoring of environmental odors is being developed. The aim of this work is to show the laboratory tests conducted to evaluate the capability of the electronic nose to recognize some specific environmentally important gases at their odor detection threshold concentration. The laboratory studies up to now focused on ammonia and butyric acid, those being compounds that can typically be found in the emissions from waste treatment plants, that may cause health effects when they exceed a given concentration level. The laboratory tests proved the sensors to be sensitive towards the considered compounds and the system to be capable of discriminating between odorous or non-odorous air, with a detection limit comparable with the detection limit of human nose.

Dentoni, Licinia; Capelli, Laura; Sironi, Selena; Del Rosso, Renato; Centola, Paolo; Della Torre, Matteo; Demattè, Fabrizio

2011-09-01

105

Different thresholds for detection and discrimination of odors in the honey bee (Apis mellifera).  

PubMed

Naturally occurring odors used by animals for mate recognition, food identification and other purposes must be detected at concentrations that vary across several orders of magnitude. Olfactory systems must therefore have the capacity to represent odors over a large range of concentrations regardless of dramatic changes in the salience, or perceived intensity, of a stimulus. The stability of the representation of an odor relative to other odors across concentration has not been extensively evaluated. We tested the ability of honey bees to discriminate pure odorants across a range of concentrations at and above their detection threshold. Our study showed that pure odorant compounds became progressively easier for honey bees to discriminate with increasing concentration. Discrimination is, therefore, a function of odorant concentration. We hypothesize that the recruitment of sensory cell populations across a range of concentrations may be important for odor coding, perhaps by changing its perceptual qualities or by increasing its salience against background stimuli, and that this mechanism is a general property of olfactory systems. PMID:14977809

Wright, Geraldine A; Smith, Brian H

2004-02-01

106

Threshold of Nuchal Translucency for the Detection of Chromosomal Aberration: Comparison of Different Cut-offs  

PubMed Central

This study evaluated the sensitivities and false positive rates of the screening test using ultrasonographic measurement of thickness of nuchal translucency (NT) with different cut-offs for chromosomal aberration in a Korean population. We included 2,570 singleton pregnancies undergoing ultrasound between 11 weeks and 14 weeks of gestation in this study. We analyzed the sensitivities of NT alone for screening chromosomal aberration using three cut-offs -2.5 mm, 3.0 mm, and 95th percentile for each crown rump length (CRL). There were 31 chromosomal aberrations (1.2%) including 12 cases of trisomy 21. The numbers of chromosomal aberrations that were detected by NT with different cut-offs of 2.5 mm, 3.0 mm and the 95th percentile CRL were 22, 18 and 23, respectively. At a threshold of 2.5 mm, the sensitivity and the false positive rate for total chromosomal aberrations were 67.7% and 6.3%, respectively. At 3.0 mm, those were 54.8% and 3.5%, respectively. At the 95th percentile CRL, those were 70.9% and 5.8%, respectively. The use of CRL-dependent cut-offs for nuchal translucency improves the detection of chromosomal aberrations when compared to fixed cut-offs in a Korean population.

Kim, Min-Hyoung; Park, Su-Hyun; Cho, Hye-Jin; Choi, June-Seek; Kim, Joo-Oh; Ahn, Hyun-Kyong; Shin, Joong-Sik; Han, Jung-Yeol; Kim, Moon-Young

2006-01-01

107

Location Performance and Detection Magnitude Threshold of the Romanian National Seismic Network  

NASA Astrophysics Data System (ADS)

Romania is an earthquake prone area with a few destructive earthquakes per century. The National Institute for Earth Physics carries out the seismic survey of Romania through the Romanian National Seismic Network (RNSN) consisting of 65 real-time seismic stations. Daily reports and monthly bulletins are delivered after routinely analyzing and processing the recorded data. In the present paper we applied the Seismic Network Evaluation through Simulation method for the RNSN configuration as it was in August 2011 to estimate the background noise level, assess the appropriateness of the velocity model adopted in routine location procedure, evaluate the hypocenter location uncertainty and determine the detection magnitude threshold. Areas of greater (southern Romania) and lower (Carpathians and Apuseni Mountains) background noise within the RNSN are identified by mapping the average power of noise in 1-12 Hz frequency range. The statistical study of the P and S phases residual times allow us to assess the appropriateness of the velocity model used in routine location. Both P- and S-wave velocity models can be optimized to improve the quality of the hypocenter location. As shown by our analysis, the RNSN is able to detect and locate earthquakes with M L magnitude above 2.5 anywhere on the Romanian territory, except the border areas, such as the Crisana-Maramures seismic source zone. Merging data from both sides of the border significantly improves the quality of hypocenter location in these areas.

D'Alessandro, Antonino; D?ne?, Anton; Grecu, Bogdan

2012-12-01

108

Threshold phenomena in low-energy electron-polar-molecule collisions: The nonlocal resonance model  

NASA Astrophysics Data System (ADS)

The basic aspects of the nonlocal resonance model based on the projection-operator formalism are discussed with application to the threshold phenomena in low-energy electron-HCl collisions. It is shown that this model coherently describes the structures which have been experimentally observed in the v=0 --> 1 vibrational excitation function of e+HCL, namely the board resonance feature, the threshold peak, as well as boomerang-type oscillations below the dissociative-attachment threshold, in terms of a single (nonlocal, energy-dependent, and complex) potential-energy function of HCl-. A new time-dependent picture of the dynamics of the e+HCl collision complex is presented which lucidly reveals the nonadiabatic character of the dynamics of HCl-.

Domcke, W.

1990-04-01

109

Energy Detectives at Work  

NSDL National Science Digital Library

Students search for clues of energy around them. They use what they find to create their own definition of energy. They also relate their energy clues to the engineering products they encounter every day.

Integrated Teaching And Learning Program

110

Optical damage threshold and energy deposition in the embedded nanostructures  

NASA Astrophysics Data System (ADS)

Results of energy deposition measurement in interaction between an ultra-short laser pulse and nanostructured target are described. As a target we used carbon nanotubes and multilayer graphene deposited on a sapphire wafer surface and embedded in a layer of protein. A 25 fs, p-polarised pulses from a 1 kHz-Ti;sapphire laser of energy up to 3 mJ were focused to give intensity up to 2×1016 W/cm2 on a target positioned within an integrating sphere. The absorption measured showed a level in excess of 80 %, increasing with the intensity. The results suggest that the host material (lysozyme) is responsible for the breakdown while the embedded material contributes dominantly to the absorption.

Janulewicz, Karol A.; Lee, Hak Jae; Hapiddin, Asep; Matouš, Bohuslav; Kim, Chul Min; Joseph, Dickson; Geckeler, K. E.; Nickles, Peter V.

2012-11-01

111

Dissociation Thresholds of Low-Energy Molecular Ions on a Cu(111) Surface  

NASA Astrophysics Data System (ADS)

The dissociation thresholds of polyatomic SF5+ and BF2+ ions on Cu(111) surface have been investigated in the incident energy range of 2 200 eV. The mass and kinetic energy of scattered ions were analyzed simultaneously using a quadrupole mass analyzer equipped with a 45° sector field energy filter. For SF5+ ion irradiation, dissociated species (SF4+ and F-) began to emerge at an energy of 15±2 eV, and the irradiated ions further dissociated into SF3+ at 50±2 eV. These energies are substantially higher than the bond strength of S F for free SF6 molecules (3.3 eV). These results suggest that the translational-vibrational energy transfer during the collision process greatly affects the observed dissociation threshold. Similar results are also observed for BF2+ irradiation.

Yamamoto, Hiroyuki; Baba, Yuji; Sasaki, Teikichi

1998-09-01

112

Disaggregated energy consumption and GDP in Taiwan: A threshold co-integration analysis  

Microsoft Academic Search

Energy consumption growth is much higher than economic growth for Taiwan in recent years, worsening its energy efficiency. This paper provides a solid explanation by examining the equilibrium relationship between GDP and disaggregated energy consumption under a non-linear framework. The threshold co-integration test developed with asymmetric dynamic adjusting processes proposed by Hansen and Seo [Hansen, B.E., Seo, B., 2002. Testing

Jin-Li Hu; Cheng-Hsun Lin

2008-01-01

113

Inelastic processes in e --HCl collisions in the energy range including the dissociation threshold  

SciTech Connect

Inelastic processes in low-energy collisions of electrons with HCl molecules are considered. We present results of calculations of vibrational excitation cross sections from the ground state and vibrationally excited states, dissociative attachment cross sections, and electron-impact dissociation cross sections near threshold. Our approach is based on the resonance {ital R}-matrix theory with the quasiclassical treatment of the nuclear motion. We use a rigorous procedure for the inclusion of the vibrational continuum. This allows for calculations of the cross sections in the energy range including dissociation threshold. The results for the dissociation cross sections are analyzed from the point of view of the threshold law for the three-particle break-up process.

Fabrikant, I.I.; Kalin, S.A.; Kazansky, A.K. (Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska (USA))

1991-10-01

114

Threshold displacement energies and defect formation energies in Y2Ti2O7  

SciTech Connect

Ab initio molecular dynamics simulations have been carried out to determine the threshold displacement energies Ed and the corresponding defect configurations, and ab initio methods have been used to accurately determine their formation energies in Y2Ti2O7. The minimum Ed is found to be 27 eV for a Y recoil along the <100> direction, 31.5 eV for Ti atoms along the <100> direction, 14.5 eV for O48f atoms along the <110> direction and 13 eV for O8b atoms along the <111> direction. The average Ed value determined is 32.7, 34.2, 14.2 and 16.1 eV for yttrium, titanium, O48f and O8b atoms, respectively. Cation interstitials at vacant 8a sites, which are generally occupied by oxygen anions, and at the bridge sites between two neighboring cations along the <010> direction are observed after low energy recoil events. A systematic study of defect formation energies suggests that cation interstitials, which are located at 8a sites and bridge sites along the <010> direction, and in split configurations along the <010>, <110> or <111> direction, are all stable with low defect formation energies. It is suggested that the relative stability of cation interstitials may provide a pathway of driving ion-irradiation induced amorphization in Y2Ti2O7.

Xiao, Haiyan [Pacific Northwest National Laboratory (PNNL); Gao, Fei [Pacific Northwest National Laboratory (PNNL); Weber, William J [ORNL

2010-01-01

115

Enhanced detection threshold for in vivo cortical stimulation produced by Hebbian conditioning  

NASA Astrophysics Data System (ADS)

Normal brain function requires constant adaptation, as an organism learns to associate important sensory stimuli with the appropriate motor actions. Neurological disorders may disrupt these learned associations and require the nervous system to reorganize itself. As a consequence, neural plasticity is a crucial component of normal brain function and a critical mechanism for recovery from injury. Associative, or Hebbian, pairing of pre- and post-synaptic activity has been shown to alter stimulus-evoked responses in vivo; however, to date, such protocols have not been shown to affect the animal's subsequent behavior. We paired stimulus trains separated by a brief time delay to two electrodes in rat sensorimotor cortex, which changed the statistical pattern of spikes during subsequent behavior. These changes were consistent with strengthened functional connections from the leading electrode to the lagging electrode. We then trained rats to respond to a microstimulation cue, and repeated the paradigm using the cue electrode as the leading electrode. This pairing lowered the rat's ICMS-detection threshold, with the same dependence on intra-electrode time lag that we found for the functional connectivity changes. The timecourse of the behavioral effects was very similar to that of the connectivity changes. We propose that the behavioral changes were a consequence of strengthened functional connections from the cue electrode to other regions of sensorimotor cortex. Such paradigms might be used to augment recovery from a stroke, or to promote adaptation in a bidirectional brain-machine interface.

Rebesco, James M.; Miller, Lee E.

2011-02-01

116

Neutron capture reaction in oxygen nuclei near threshold energy regions  

SciTech Connect

For the key reactions {sup 16}O(n,{gamma}){sup 17}O and {sup 17}O(n,{gamma}){sup 18}O on nucleosyntheses in stellar interior, the theoretical estimate for the cross section and reaction rate have been made. The careful description of the nuclear structure is important in very low energy regions. The Cluster Orbital Shell Model is adopted for reproducing the structure of the nuclei. Our results for the cross section of the {sup 16}O(n,{gamma}){sup 17}O reaction are consistent with that of the microscopic two cluster model. The straightforward application becames possible to the case of the {sup 17}O(n,{gamma}){sup 18}O reaction with a substantial reliance.

Yamamoto, K.; Ohta, M. [Department of Physics, Konan University, 8-9-1 Okamoto, Kobe 658-8501 (Japan); Masui, H. [Information Processing Center, Kitami Institute of Technology, Kitami 090-8507 (Japan); Kato, K. [Division of Physics, Hokkaido University, Sapporo 060-0810 (Japan); Wada, T. [Department of Pure and Applied Physics, Kansai University, 3-3-35 Yamate-cho, Suita 564-8680 (Japan)

2008-05-21

117

[Boundary threshold value method used in crystalline material internal defect detection by short wavelength X-ray diffraction].  

PubMed

There are few references about crystalline material internal defect detected by X-ray diffraction tomography using common X-ray source. Short wavelength X-ray diffractometer (SWXRD), invented by Institute of Southwest Technology Engineering, is a relatively small and inexpensive instrument compared to synchrotron radiation or neutron reactor. Boundary determination of defect affects the imaging quality and the distinguishing of defect in X-ray diffraction tomography using SWXRD. In the present paper, threshold value method of diffracted intensity is put forward to process the test data, so the boundary of defect is legible. In order to study how the factors influence the threshold value, Gauss function is used in fitting the test data. The influence of varisized image quality indicator pressed in powdered aluminum on threshold value has been studied. The result shows that 91% of the diffraction intensity of substrate can be regarded as the threshold value. The experiment of slit in aluminum alloy sheet further verified the threshold value method. It's useful in detecting the defect boundary. PMID:21847964

Mu, Jian-Lei; Zhang, Jin; Gao, Zheng-Huan; Zheng, Lin; He, Chang-Guang

2011-06-01

118

First demonstration of a sub-keV electron recoil energy threshold in a liquid argon ionization chamber  

NASA Astrophysics Data System (ADS)

We describe the first demonstration of a sub-keV electron recoil energy threshold in a dual-phase liquid argon time projection chamber. This is an important step in an effort to develop a detector capable of identifying the ionization signal resulting from nuclear recoils with energies of order a few keV and below. We obtained this result by observing the peaks in the energy spectrum at 2.82 keV and 0.27 keV, following the K- and L-shell electron capture decay of 37Ar respectively. The 37Ar source preparation is described in detail, since it enables calibration that may also prove useful in dark matter direct detection experiments. An internally placed 55Fe x-ray source simultaneously provided another calibration point at 5.9 keV. We discuss the ionization yield and electron recombination in liquid argon at those three calibration energies.

Sangiorgio, S.; Joshi, T. H.; Bernstein, A.; Coleman, J.; Foxe, M.; Hagmann, C.; Jovanovic, I.; Kazkaz, K.; Mavrokoridis, K.; Mozin, V.; Pereverzev, S.; Sorensen, P.

2013-11-01

119

Modifying the high-energy part of the above-threshold-ionization spectrum  

SciTech Connect

We show that the high-energy part of the above-threshold-ionization spectrum can be modified considerably if a driving laser pulse composed of several harmonic frequencies is used. To find such a pulse we rely on classical calculation. We present results of the quantum-mechanical calculation confirming classical results.

Ivanov, I. A. [Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2010-09-15

120

Ischemic Thresholds of Cerebral Protein Synthesis and Energy State Following Middle Cerebral Artery Occlusion in Rat  

Microsoft Academic Search

Summary: The ischemic threshold of protein synthesis and energy state was determined 1,6, and 12 h after middle cerebral artery (MCA) occlusion in rats. Local blood flow and amino acid incorporation were measured by double tracer autoradiography, and local ATP content by substrate-induced bioluminescence. The various images were evaluated at the striatal level in cerebral cortex by scanning with a

G. Mies; S. Ishimaru; Y. Xie; K. Seo; K.-A. Hossmann

1991-01-01

121

Threshold displacement energies and defect formation energies in Y2Ti2O7  

SciTech Connect

Ab initio molecular dynamics simulations have been carried out to determine both the threshold displacement energies Ed and corresponding defect configurations, and ab initio methods have been used to accurately determine the formation energies in Y2Ti2O7. The minimum Ed is found to be 27 eV for a Y recoil along the <100> direction, 31.5 eV for Ti atoms along the <100> direction, 14.5 eV for O48f atoms along the <110> direction and 13 eV for O8b atoms along the <111> direction. The average Ed value along three directions determined is 35.1, 35.4, 17.0 and 16.2 eV for yttrium, titanium, O48f and O8b atoms, respectively. Cation interstitials at vacant 8a sites, which are generally occupied by oxygen anions, and at the bridge sites between two neighboring cations along the <010> direction are observed after low energy recoil events. A systematic study of the defect formation energies suggests that cation interstitials, which are located at 8a sites and bridge sites along the <010> direction, and in split configurations along the <010>, <110> or <111> direction, are all stable in these configurations. It is suggested that the relative stability of cation interstitials may provide a pathway of driving ion-irradiation induced amorphization in Y2Ti2O7.

Xiao, Haiyan Y.; Gao, Fei; Weber, William J.

2010-10-20

122

Threshold displacement energies and defect formation energies in Y2Ti2O7  

NASA Astrophysics Data System (ADS)

Ab initio molecular dynamics simulations have been carried out to determine both threshold displacement energies, Ed, and corresponding defect configurations, and ab initio methods have been used to determine defect formation energies in Y2Ti2O7. The minimum Ed is found to be 27 eV for a Y recoil along the lang100rang direction, 31.5 eV for Ti atoms along the lang100rang direction, 14.5 eV for O48f atoms along the lang110rang direction and 13 eV for O8b atoms along the lang111rang direction. The average Ed values along three directions determined here are 35.1, 35.4, 17.0 and 16.2 eV for yttrium, titanium, O48f and O8b atoms, respectively. Cation interstitials are observed occupying vacant 8a anion sites and bridge sites between two neighboring cations along the lang010rang direction after low energy recoil events. A systematic study of the defect formation energies suggests that cation interstitials that are located at 8a sites, at bridge sites along the lang010rang direction and in split configurations along the lang010rang, lang110rang or lang111rang direction are all stable configurations. It is suggested that the relative stability of cation interstitials may provide a pathway for driving irradiation induced amorphization in Y2Ti2O7.

Xiao, H. Y.; Gao, F.; Weber, W. J.

2010-10-01

123

Threshold displacement energies and defect formation energies in Y2Ti2O7.  

PubMed

Ab initio molecular dynamics simulations have been carried out to determine both threshold displacement energies, E(d), and corresponding defect configurations, and ab initio methods have been used to determine defect formation energies in Y(2)Ti(2)O(7). The minimum E(d) is found to be 27 eV for a Y recoil along the {100} direction, 31.5 eV for Ti atoms along the {100} direction, 14.5 eV for O(48f) atoms along the {110} direction and 13 eV for O(8b) atoms along the {111} direction. The average E(d) values along three directions determined here are 35.1, 35.4, 17.0 and 16.2 eV for yttrium, titanium, O(48f) and O(8b) atoms, respectively. Cation interstitials are observed occupying vacant 8a anion sites and bridge sites between two neighboring cations along the {010} direction after low energy recoil events. A systematic study of the defect formation energies suggests that cation interstitials that are located at 8a sites, at bridge sites along the {010} direction and in split configurations along the {010}, {110} or {111} direction are all stable configurations. It is suggested that the relative stability of cation interstitials may provide a pathway for driving irradiation induced amorphization in Y(2)Ti(2)O(7). PMID:21386601

Xiao, H Y; Gao, F; Weber, W J

2010-09-27

124

A threshold-based approach to calorimetry in helium droplets: measurement of binding energies of water clusters.  

PubMed

Helium droplet beam methods have emerged as a versatile technique that can be used to assemble a wide variety of atomic and molecular clusters. We have developed a method to measure the binding energies of clusters assembled in helium droplets by determining the minimum droplet sizes required to assemble and detect selected clusters in the spectrum of the doped droplet beam. The differences in the droplet sizes required between the various multimers are then used to estimate the incremental binding energies. We have applied this method to measure the binding energies of cyclic water clusters from the dimer to the tetramer. We obtain measured values of D(0) that are in agreement with theoretical estimates to within ?20%. Our results suggest that this threshold-based approach should be generally applicable using either mass spectrometry or optical spectroscopy techniques for detection, provided that the clusters selected for study are at least as strongly bound as those of water, and that a peak in the overall spectrum of the beam corresponding only to the cluster chosen (at least in the vicinity of the threshold) can be located. PMID:22852673

Lewis, William K; Harruff-Miller, Barbara A; Gord, Michael A; Gord, Joseph R; Guliants, Elena A; Bunker, Christopher E

2012-07-01

125

A vertical-energy-thresholding procedure for data reduction with multiple complex curves.  

PubMed

Due to the development of sensing and computer technology, measurements of many process variables are available in current manufacturing processes. It is very challenging, however, to process a large amount of information in a limited time in order to make decisions about the health of the processes and products. This paper develops a "preprocessing" procedure for multiple sets of complicated functional data in order to reduce the data size for supporting timely decision analyses. The data type studied has been used for fault detection, root-cause analysis, and quality improvement in such engineering applications as automobile and semiconductor manufacturing and nanomachining processes. The proposed vertical-energy-thresholding (VET) procedure balances the reconstruction error against data-reduction efficiency so that it is effective in capturing key patterns in the multiple data signals. The selected wavelet coefficients are treated as the "reduced-size" data in subsequent analyses for decision making. This enhances the ability of the existing statistical and machine-learning procedures to handle high-dimensional functional data. A few real-life examples demonstrate the effectiveness of our proposed procedure compared to several ad hoc techniques extended from single-curve-based data modeling and denoising procedures. PMID:17036818

Jung, Uk; Jeong, Myong K; Lu, Jye-Chyi

2006-10-01

126

Threshold displacement energies in rutile TiO2: A molecular dynamics simulation study  

SciTech Connect

Threshold displacement energies are determined for Ti and O in rutile TiO2 using molecular dynamics simulations with an empirical model. The simulations involve the introduction of a primary knock-on atom (PKA) with a range of energies (30- 150 eV) in various crystallographic directions at 160 K. We observe the formation of stable Frenkel defects, as well as defect recovery via low-energy interstitial migration mechanisms. The latter causes significant statistical variation between simulation outcomes, which leads to the definition of a defect formation probability. This probability is characterized as a function of PKA energy in order to define the threshold displacement energy and compare with experimental results. Using a probability of 10%, the average threshold displacement energy is around 40 eV for oxygen (comparable to experiment) and 105 eV for titanium. Using a probability of 50%, the values are 65 eV and 130 eV respectively, which may be more appropriate for use in TRIM calculations. In addition, we run a parallel set of calculations using a second empirical model, finding that the detailed results are highly model-dependent, particularly the oxygen defect structures and energies, which are compared to new ab initio data.

Thomas, Bronwyn S.; Marks, Nigel A.; Corrales, Louis R.; Devanathan, Ram

2005-09-01

127

Silicon threshold displacement energy determined by photoluminescence in electron-irradiated cubic silicon carbide  

SciTech Connect

In view of the potential use of silicon carbide (SiC) in the nuclear industry, it is of major interest to understand point defect formation in this material. This work is a contribution to the determination of the silicon threshold displacement energy in the cubic polytype of SiC using electron irradiations with increasing energies from 275 to 680 keV. The photoluminescence signal of the silicon vacancy was related to the number of displacements per atom in the silicon sublattice. This quantity was calculated taking into account the energy loss and angular dispersion of electrons in the target. A best fit of experimental data was obtained for a displacement cross section using a threshold displacement energy of 25 eV along the [100] lattice direction. We checked the relevance of this result by comparing the experimental concentration of silicon single vacancies measured by electron paramagnetic resonance spectroscopy with the theoretical number of displaced silicon atoms.

Lefevre, Jeremie; Esnouf, Stephane; Petite, Guillaume [Laboratoire des Solides Irradies, CEA-IRAMIS, CNRS, Ecole Polytechnique, F-91128 Palaiseau Cedex (France); Costantini, Jean-Marc [CEA, DEN, SRMA, F-91191 Gif-sur-Yvette Cedex (France)

2009-01-15

128

Can Receptor Potentials Be Detected With Threshold Tracking in Rat Cutaneous Nociceptive Terminals?  

Microsoft Academic Search

Abstract Threshold tracking of individual polymodal,C- and,A? -fibre terminals was,used,to assess membrane,potential changes,induced by de- or hyperpolarizing stimuli in the isolated rat skin -nerve preparation. Constant current pulses were,delivered (1Hz) through,a tungsten microelectrode inserted in the receptive field and the current amplitude was,controlled by feedback with a lab,computer,programmed,to serially determine,the electrical threshold using the method of limits. During threshold tracking,

S. K. Sauer; C. Weidner; R. W. Carr; B. Averbeck; U. Nesnidal; P. W. Reeh

2005-01-01

129

Collisional energy deposition threshold for extended damage depths in ion-implanted silicates  

Microsoft Academic Search

Many properties of implanted fused silica (e.g., surface stress, hardness) exhibit maximum implantation-induced changes for collisional energy deposition values of approx. 10(exp 20) keV\\/cu cm. We have observed a second critical energy deposition threshold value of about 10(exp 22) keV\\/cu cm in stress and hardness measurements as well as in many other experiments on silicate glasses (leaching, alkali depletion, etching

G. W. Arnold; G. Battaglin; A. Boscolo-Boscoletto; F. Caccavalle; G. De Marchi; P. Mazzoldi; A. Miotello

1991-01-01

130

An energy-time analysis of ventricular fibrillation and defibrillation thresholds with internal electrodes  

Microsoft Academic Search

The paper describes experimentation with the intracardiac production and termination of ventricular fibrillation, the ultimate\\u000a goal being the design of an automatic implantable defibrillation device. Fibrillation and defibrillation thresholds were identified\\u000a by means of increasing electrical-shock energies on dogs via internal electrodes. A maximum energy, called VF type I (VF1), has been demonstrated and is defined as the highest electrical-shock

C. Lesigne; B. Levy; R. Saumont; P. Birkui; A. Bardou; B. Rubin

1976-01-01

131

Determination of threshold energy dose for ultrasound-induced transdermal drug transport.  

PubMed

Low-frequency (20 kHz) ultrasound has been shown to enhance transdermal transport of drugs, a phenomenon referred to as sonophoresis. In this paper, we report the threshold energy dose for ultrasound-induced transdermal drug transport. The threshold was determined by in vitro measurements of the dependence of sonophoretic enhancement on ultrasound parameters, including intensity, duty cycle, and exposure time. While the enhancement varies linearly with ultrasound intensity and exposure times, it is independent of the duty cycle in the range of parameters studied. The enhancement is also directly proportional to the ultrasound energy density once the threshold value is crossed. For full thickness pig skin, the threshold value is about 222 J/cm(2). The overall dependence of transport enhancement on ultrasound parameters is similar to that of cavitation measured in a model system, pitting of aluminum foil. Specifically, the extent of pitting is proportional to ultrasound intensity and exposure time and is independent of duty cycle. Furthermore, the extent of pitting is also proportional to the ultrasound energy density. The similarity between the parametric dependence of transport enhancement and cavitation is consistent with previous findings that cavitation plays the dominant role in sonophoresis. PMID:10640579

Mitragotri, S; Farrell, J; Tang, H; Terahara, T; Kost, J; Langer, R

2000-01-01

132

Near peripheral motion detection threshold correlates with self-reported failures of attention in younger and older drivers.  

PubMed

Motion contrast thresholds for 0.4cycle/degree drifting Gabor stimuli were assessed at 15 degrees eccentricity in the right and left visual fields for 16 younger drivers (ages 24-42), and 15 older drivers (ages 65-84), using a temporal two-alternative forced choice staircase procedure. Two self-report questionnaires that assess failures of attention while driving-the Driver Perception Questionnaire (DPQ5), and an abridged Aging Driver Questionnaire (ADQ15)-were administered. The three UFOV((R)) subtests of attention and processing speed were also administered. Mean peripheral motion contrast threshold (PMCT) of older drivers was significantly higher than that of younger drivers. When controlling for age, PMCT thresholds correlated significantly with both DPQ5 and ADQ15 while the UFOV((R)) subtests were found not to correlate with PMCT results. The potential value of the PMCT as an assessment of drivers' hazard detection capacity is discussed. PMID:20441830

Henderson, Steven; Gagnon, Sylvain; Bélanger, Alexandre; Tabone, Ricardo; Collin, Charles

2010-02-16

133

Unconscious inhibition and facilitation at the objective detection threshold: replicable and qualitatively different unconscious perceptual effects.  

PubMed

Although the veridicality of unconscious perception is increasingly accepted, core issues remain unresolved [Jack, A., & Shallice, T. (2001). Introspective physicalism as an approach to the science of consciousness. Cognition, 79, 161-196], and sharp disagreement persists regarding fundamental methodological and theoretical issues. The most critical problem is simple but tenacious-namely, how to definitively rule out weak conscious perception as an alternative explanation for putatively unconscious effects. Using a direct task and objectively undetectable stimuli, the current experiments demonstrate clearly reliable unconscious perceptual effects, which differ qualitatively from weakly conscious effects in fundamental ways. Most importantly, the current effects correlate negatively with stimulus detectability, directly rebutting the exhaustiveness, null sensitivity, and exclusiveness problems [Reingold, E., & Merikle, P. (1988). Using direct and indirect measures to study perception without awareness. Perception & Psychophysics, 44, 563-575; Reingold, E., & Merikle, P. (1990). On the inter-relatedness of theory and measurement in the study of unconscious processes. Mind and Language, 5, 9-28)], which all predict positive correlations. Moreover, the current effects are entirely bidirectional [Katz, (2001). Bidirectional experimental effects. Psychological Methods, 6, 270-281)] and radically uncontrollable, including below-chance performance despite intentions to facilitate. In contrast, weakly conscious effects on direct measures are unidirectional, facilitative, and potentially controllable. Moreover, these qualitative differences also suggest that objective and subjective threshold phenomena are fundamentally distinct, rather than the former simply being a weaker version of the latter [Merikle, P., Smilek, D., Eastwood, J. (2001). Perception without awareness: Perspectives from cognitive psychology. Cognition, 79, 115-134]. Accordingly, it is important to distinguish between rather than conflate these methods. Further, the current effects reinforce recent work [e.g. Naccache, L., Blandin, E., & Dehaene, S. (2002). Unconscious masked priming depends on temporal attention. Psychological Science, 13, 416-424] demonstrating that unconscious effects, although not selectively controllable, are nonetheless mediated by strategic and individual difference factors, rather than being immune to such influences as long thought. PMID:16289068

Snodgrass, Michael; Shevrin, Howard

2005-11-08

134

Automated Detection of Macular Drusen Using Geometric Background Leveling and Threshold Selection  

PubMed Central

Background Age-related macular degeneration (ARMD) is the most prevalent cause of visual loss in patients older than 60 years in the United States. Observation of drusen is the hallmark finding in the clinical evaluation of ARMD. Objectives To segment and quantify drusen found in patients with ARMD using image analysis and to compare the efficacy of image analysis segmentation with that of stereoscopic manual grading of drusen. Design Retrospective study. Setting University referral center. Patients Photographs were randomly selected from an available database of patients with known ARMD in the ongoing Columbia University Macular Genetics Study. All patients were white and older than 60 years. Interventions Twenty images from 17 patients were selected as representative of common manifestations of drusen. Image preprocessing included automated color balancing and, where necessary, manual segmentation of confounding lesions such as geographic atrophy (3 images). The operator then chose among 3 automated processing options suggested by predominant drusen type. Automated processing consisted of elimination of background variability by a mathematical model and subsequent histogram-based threshold selection. A retinal specialist using a graphic tablet while viewing stereo pairs constructed digital drusen drawings for each image. Main Outcome Measures The sensitivity and specificity of drusen segmentation using the automated method with respect to manual stereoscopic drusen drawings were calculated on a rigorous pixel-by-pixel basis. Results The median sensitivity and specificity of automated segmentation were 70% and 81%, respectively. After preprocessing and option choice, reproducibility of automated drusen segmentation was necessarily 100%. Conclusions Automated drusen segmentation can be reliably performed on digital fundus photographs and result in successful quantification of drusen in a more precise manner than is traditionally possible with manual stereoscopic grading of drusen. With only minor preprocessing requirements, this automated detection technique may dramatically improve our ability to monitor drusen in ARMD.

Smith, R. Theodore; Chan, Jackie K.; Nagasaki, Takayuki; Ahmad, Umer F.; Barbazetto, Irene; Sparrow, Janet; Figueroa, Marta; Merriam, Joanna

2010-01-01

135

A STATISTICAL MODELING METHODOLOGY FOR THE DETECTION, QUANTIFICATION, AND PREDICTION OF ECOLOGICAL THRESHOLDS  

EPA Science Inventory

This study will provide a general methodology for integrating threshold information from multiple species ecological metrics, allow for prediction of changes of alternative stable states, and provide a risk assessment tool that can be applied to adaptive management. The integr...

136

Ultrahigh Energy Cosmic Rays Detection  

SciTech Connect

The paper describes methods used for the detection of cosmic rays with energies above 1018 eV (UHECR, UltraHigh Energy Cosmic Rays). It had been anticipated there would be a cutoff in the energy spectrum of primary cosmic rays around 3{center_dot}1019 eV induced by their interaction with the 2.7 deg. K primordial photons. This has become known as the GZK cutoff. However, several showers have been detected with estimated primary energy exceeding this limit.

Aramo, Carla [Istituto Nazionale di Fisica Nucleare - Sezione di Napoli, Complesso Universitario di Monte Sant'Angelo, Via Cintia, 80126 - Naples (Italy)

2005-10-12

137

Collisional energy deposition threshold for extended damage depths in ion-implanted silicates  

SciTech Connect

Many properties of implanted fused silica (e.g., surface stress, hardness) exhibit maximum implantation-induced changes for collisional energy deposition values of {approximately}10{sup 20} keV/cm{sup 3}. We have observed a second critical energy deposition threshold value of about 10{sup 22} keV/cm{sup 3} in stress and hardness measurements as well as in many other experiments on silicate glasses (leaching, alkali depletion, etching rate, gaseous implant redistribution). The latter show evidence for damage depths exceeding TRIM ranges by about a factor of 2. For crystalline quartz, a similar threshold value has been found for extended damage depths (greater than TRIM) for 250 kev ions (H-Au) as measured by RBS and interference fringes. This phenomenon at high damage deposition energy may involve the large stress gradients between damaged and undamaged regions and the much increased diffusion coefficient for defect transport. 13 refs., 6 figs.

Arnold, G.W. (Sandia National Labs., Albuquerque, NM (United States)); Battaglin, G. (Consorzio INFM, Dipartimento di Chimica Fisica, Universita di Venezia, (Italy)); Boscolo-Boscoletto, A. (Centro Ricerche Montedipe, Porto Marghera (Italy)); Caccavalle, F.; De Marchi, G.; Mazzoldi, P. (Consorzio INFM, Dipartimento di Fisica, Universita di Padova, (Italy)); Miotello, A. (Consorzio INFM, Dipartiment

1991-01-01

138

Collisional energy deposition threshold for extended damage depths in ion-implanted silicates  

SciTech Connect

Many properties of implanted fused silica (e.g., surface stress, hardness) exhibit maximum implantation-induced changes for collisional energy deposition values of {approximately}10{sup 20} keV/cm{sup 3}. We have observed a second critical energy deposition threshold value of about 10{sup 22} keV/cm{sup 3} in stress and hardness measurements as well as in many other experiments on silicate glasses (leaching, alkali depletion, etching rate, gaseous implant redistribution). The latter show evidence for damage depths exceeding TRIM ranges by about a factor of 2. For crystalline quartz, a similar threshold value has been found for extended damage depths (greater than TRIM) for 250 kev ions (H-Au) as measured by RBS and interference fringes. This phenomenon at high damage deposition energy may involve the large stress gradients between damaged and undamaged regions and the much increased diffusion coefficient for defect transport. 13 refs., 6 figs.

Arnold, G.W. [Sandia National Labs., Albuquerque, NM (United States); Battaglin, G. [Consorzio INFM, Dipartimento di Chimica Fisica, Universita di Venezia, (Italy); Boscolo-Boscoletto, A. [Centro Ricerche Montedipe, Porto Marghera (Italy); Caccavalle, F.; De Marchi, G.; Mazzoldi, P. [Consorzio INFM, Dipartimento di Fisica, Universita di Padova, (Italy); Miotello, A. [Consorzio INFM, Dipartimento di Fisica, Universita di Trento, Povo (Italy)

1991-12-31

139

Signal detection theory and vestibular perception: II. Fitting perceptual thresholds as a function of frequency.  

PubMed

Vestibular perceptual thresholds are defined by a dynamic sensory system. To capture these dynamics, thresholds were previously fit as a function of frequency. In this paper, we compare fits using two published models with two new models. Furthermore, a new fitting method that utilizes vestibular perceptual dynamics is developed to improve fit quality and overcome problems associated with the conventional approach. Combinations of the four models and two fitting methods are tested using both simulated data and previously published experimental data. Simulations reveal that the conventional approach underestimates thresholds when the number of trials at each frequency is limited (circa 50); this underestimation is reduced fivefold by the new fitting method that simultaneously utilizes data across frequencies. The new fitting method also scored best for goodness of fit for both the simulations and experimental data. In fact, the new approach of fitting simultaneously across frequencies proved more accurate, more precise, more robust, and more efficient than the conventional approach of fitting the responses at each frequency individually and then fitting these threshold data across frequency. The revised fit of published yaw rotation threshold data shows that these are best fit by a first-order high-pass filter having a plateau of 0.5°/s (roughly a factor of 4 higher than the motion platform vibration) at frequencies above the cutoff frequency of 0.26 Hz, which is well above the cutoff frequency of the semicircular canals (circa 0.03 Hz). This dynamic analysis suggests the contributions of a velocity leakage mechanism to human yaw rotation thresholds. PMID:22923225

Lim, Koeun; Merfeld, Daniel M

2012-08-26

140

Threshold reduction of a tunable organic laser using effective energy transfer  

Microsoft Academic Search

The paper presents a reliable organic solid-state tunable laser. Distributed-feedback lasing of [3-(2-benzothiazolyl)-7-(diethylamino)coumarin] (Coumarin 6) in a polymeric waveguide was achieved using holographic dynamic gratings. A low-threshold energy of lasing from Coumarin 6 was achieved in a poly(N-vinylcarbazole) (PVCz) matrix waveguide and in a tris(8-quinolinolato)aluminum (Alq) dispersed polystyrene (PS) matrix waveguide. For both PVCz \\/ Coumarin 6 and PS\\/Alq\\/ Coumarin

Naoto Tsutsumi; Masaki Yamamoto

2006-01-01

141

Inelastic processes in e-HCl collisions in the energy range including the dissociation threshold  

Microsoft Academic Search

Inelastic processes in low-energy collisions of electrons with HCl molecules are considered. We present results of calculations of vibrational excitation cross sections from the ground state and vibrationally excited states, dissociative attachment cross sections, and electron-impact dissociation cross sections near threshold. Our approach is based on the resonance R-matrix theory with the quasiclassical treatment of the nuclear motion. We use

I. I. Fabrikant; S. A. Kalin; A. K. Kazansky

1991-01-01

142

Comparative study of laser damage threshold energies in the artificial retina.  

PubMed

Laser damage threshold energies produced from ultrashort (i.e., ?1?ns) laser pulses are investigated as a function of both pulse width and spot size for an artificial retina. A piece of film acts as the absorbing layer and is positioned at the focus of a variant on the Cain artificial eye [C. Cain, G. D. Noojin, D. X. Hammer, R. J. Thomas, and B. A. Rockwell, "Artificial eye for in vitro experiments of laser light interaction with aqueous media," J. Biomed. Opt.2, 88-94 (1997)]. Experiments were performed at the focal point and at two and ten Rayleigh ranges (RR) in front of the focus with the damage end point being the presence of a bubble imaged at the film plane. Pulse energy thresholds were determined for wavelengths of 1064, 580, and 532 nm with pulse durations ranging from the nanosecond (ns) to the femtosecond (fs) regime. For the at-focus data in the visible regime, the threshold dropped from 0.25 ?J for a 532 nm, 5 ns pulse to 0.11 ?J for a 580 nm, 100 fs pulse. The near-infrared (NIR) threshold changed from 5.5 ?J for a 5 ns pulse to 0.9 ?J for a 130 fs pulse at a distance two RR in front of the focus. The experiment was repeated using the same pulse widths and wavelengths, except the water path was removed to determine the impact of nonlinear self-focusing in water. A vertical microscope imaging system was employed in order to observe the threshold event. The NIR fluence threshold of 0.5 J/cm2 remained constant within an experimental uncertainty for all pulse widths, which corresponds to values in the literature [C. P. Lin and M. W. Kelly, "Ultrafast time-resolved imaging of stress transient and cavitation from short pulsed laser irradiated melanin particles," SPIE Laser-Tissue Interactions VI, Proc. SPIE2391, 294-299 (1995)]. The visible data also demonstrated a nearly constant fluence of 0.07?J/cm2. The disparity in thresholds between the two techniques arises from nonlinear optical phenomena related to propagation differences in the ocular fluid. © 1999 Society of Photo-Optical Instrumentation Engineers. PMID:23015254

Payne, D J; Hopkins, R A; Eilert, B G; Noojin, G D; Stolarski, D J; Thomas, R J; Cain, C P; Hengst, G T; Kennedy, P K; Jost, T R; Rockwell, B A

1999-07-01

143

Detection-threshold calibration and other factors influencing digital measurements of bare ground  

Technology Transfer Automated Retrieval System (TEKTRAN)

New methods of image acquisition and analysis are advancing rangeland assessment techniques. Current versions of image-analysis software require users to set thresholds for color / object classification -- a subjective process affected by human errors and inconsistencies. We measured the effect of s...

144

Ventilatory threshold detection: a new method based on heart rate variability  

Microsoft Academic Search

Ventilatory threshold (VT) is one of the best indexes of aerobic fitness, but its evaluation is laborious and expensive. The High Frequency (HF) component of the heart-rate spectrum is influenced by ventilation: thus, changes in the HF component during exercise might reflect the ventilatory adaptations occurring at VT. Eleven subjects with different aerobic fitness levels were enrolled. RR time series

G MeratiiV; S. Rampichini; E. Ce; M. Sangiovanni; P. Castiglioni; M. Di Rienzo; A. Veicsteinas

2004-01-01

145

Remarks on detecting high-energy deuterium tritium fusion gamma rays using a gas Cherenkov detector  

Microsoft Academic Search

As fusion ignition conditions are approached using the national ignition facility (NIF), independent high-bandwidth gamma-ray fusion burn measurements become essential complements to information obtained from neutron diagnostics. The 16.75-MeV gamma rays that accompany deuterium tritium (d+t) fusion can be detected using a high-bandwidth gaseous carbon dioxide Cherenkov threshold detector. The detection energy threshold was set by the CO2 gas pressure.

J. M. Mack; R. R. Berggren; S. E. Caldwell; C. R. Christensen; S. C. Evans; J. R. Faulkner Jr.; R. L. Griffith; G. M. Hale; R. S. King; D. K. Lash; R. A. Lerche; J. A. Oertel; D. M. Pacheco; C. S. Young

2006-01-01

146

Olfaction and environment: Tsimane' of bolivian rainforest have lower threshold of odor detection than industrialized german people.  

PubMed

Olfactory sensitivity varies between individuals. However, data regarding cross-cultural and inter-group differences are scarce. We compared the thresholds of odor detection of the traditional society of Tsimane' (native Amazonians of the Bolivian rainforest; n = 151) and people living in Dresden (Germany; n = 286) using "Sniffin' Sticks" threshold subtest. Tsimane' detected n-butanol at significantly lower concentrations than the German subjects. The distribution of thresholds of the Tsimane' was very specific, with 25% of Tsimane' obtaining better results in the olfactory test than any member of the German group. These data suggest that differences in olfactory sensitivity seem to be especially salient between industrialized and non-industrialized populations inhabiting different environmental conditions. We hypothesize that the possible sources of such differences are: (i) the impact of pollution which impairs the olfactory abilities of people from industrialized countries; (ii) better training of olfaction because of the higher importance of smell in traditional populations; (iii) environmental pressures shaping olfactory abilities in these populations. PMID:23922693

Sorokowska, Agnieszka; Sorokowski, Piotr; Hummel, Thomas; Huanca, Tomas

2013-07-29

147

Investigation of ion beam induced nanopattern formation near the threshold energy  

NASA Astrophysics Data System (ADS)

The nanoscale ripple formation on mica surface is studied at off-normal ion incidence angles ? under Ar+ bombardment at energies E close to or below the threshold energy for physical sputtering. A phase diagram for domains of pattern formation is presented as a function of ? and E, which shows the stability/instability bifurcation angle close to 40°. The instability grows as ripple-like structures at lower angles, while at grazing angles the pattern emerges as dense array of needles. The results support the pure mass redistribution based paradigm for surface patterning as the erosion due to sputtering essentially tends to zero.

Metya, Amaresh; Ghose, Debabrata

2013-10-01

148

Hydration Energies of Zinc(II): Threshold Collision-Induced Dissociation Experiments and Theoretical Studies  

NASA Astrophysics Data System (ADS)

The first experimentally determined sequential bond dissociation energies of Zn2+(H2O)n complexes, where n = 6-10, are measured using threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer coupled with an electrospray ionization source. Kinetic energy dependent cross sections are obtained and analyzed to yield 0 K threshold measurements for the loss of one and two water ligands after accounting for multiple collisions, kinetic shifts, and energy distributions. The threshold measurements are then converted from 0 to 298 K values to give the hydration energies for sequentially losing one water from each parent complex. Theoretical geometry optimizations and single-point energy calculations are performed using several levels of theory for comparison to experiment. Although different levels of theory disagree on the ground-state conformation of most complexes examined here leading to potential ambiguities in the final thermochemical values, calculations at the MP2(full) level provide the best agreement with experiment. On this basis, the present experiments are most consistent with the inner solvent shell of Zn2+ being five waters, except for Zn2+(H2O)6 where all waters bind directly to the metal ion. The charge separation process, Zn2+(H2O)n ? ZnOH+(H2O)m + H+(H2O)n-m-1, which is in competition with the loss of water from the parent complex, is also observed for n = 6-8. These processes are analyzed in detail in the following paper.

Cooper, Theresa E.; Carl, D. R.; Armentrout, P. B.

2009-11-01

149

The highest energy emission detected by EGRET from blazars  

NASA Astrophysics Data System (ADS)

Published EGRET spectra from blazers extend only to 10 GeV, yet EGRET has detected approximately 2000 ?-rays above 10 GeV of which about half are at high Galactic latitude. We report a search of these high-energy ?-rays for associations with the EGRET and TeV detected blazers. Because the point spread function of EGRET improves with energy, only ~2 ?-rays are expected to be positionally coincident with the 80 blazars searched, yet 23 ?-rays were observed. This collection of >10 GeV sources should be of particular interest due to the improved sensitivity and lower energy thresholds of ground-based TeV observers. One of the blazers, RGB0509+056, has the highest energy ?-rays detected by EGRET from any blazar with 2>40 GeV, and is a BL Lac type blazar with unknown redshift. .

Dingus, Brenda L.; Bertsch, David L.

2001-10-01

150

Energy correlation in above-threshold nonsequential double ionization at 800 nm  

SciTech Connect

We have investigated the energy correlation of the two electrons from nonsequential double ionization of helium atoms in 800-nm laser fields at intensities below the recollision threshold by quantum calculations. The circular arcs structure of the correlated electron momentum spectra reveals a resonant double-ionization process in which the two electrons transit from doubly excited states into continuum states by simultaneously absorbing and sharing excess energy in integer units of the photon energy. The effectiveness of Coulomb repulsion plays a decisive role in controlling the electronic dynamics in continuum states and is responsible for the dominant back-to-back electron emission and two intensity-independent cutoffs in the two-electron energy spectra.

Liao Qing; Lu Peixiang [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

2010-08-15

151

Adaptive thresholding and dynamic windowing method for automatic centroid detection of digital Shack-Hartmann wavefront sensor  

SciTech Connect

A Shack-Hartmann wavefront sensor (SWHS) splits the incident wavefront into many subsections and transfers the distorted wavefront detection into the centroid measurement. The accuracy of the centroid measurement determines the accuracy of the SWHS. Many methods have been presented to improve the accuracy of the wavefront centroid measurement. However, most of these methods are discussed from the point of view of optics, based on the assumption that the spot intensity of the SHWS has a Gaussian distribution, which is not applicable to the digital SHWS. In this paper, we present a centroid measurement algorithm based on the adaptive thresholding and dynamic windowing method by utilizing image processing techniques for practical application of the digital SHWS in surface profile measurement. The method can detect the centroid of each focal spot precisely and robustly by eliminating the influence of various noises, such as diffraction of the digital SHWS, unevenness and instability of the light source, as well as deviation between the centroid of the focal spot and the center of the detection area. The experimental results demonstrate that the algorithm has better precision, repeatability, and stability compared with other commonly used centroid methods, such as the statistical averaging, thresholding, and windowing algorithms.

Yin Xiaoming; Li Xiang; Zhao Liping; Fang Zhongping

2009-11-10

152

Adaptive thresholding and dynamic windowing method for automatic centroid detection of digital Shack-Hartmann wavefront sensor.  

PubMed

A Shack-Hartmann wavefront sensor (SWHS) splits the incident wavefront into many subsections and transfers the distorted wavefront detection into the centroid measurement. The accuracy of the centroid measurement determines the accuracy of the SWHS. Many methods have been presented to improve the accuracy of the wavefront centroid measurement. However, most of these methods are discussed from the point of view of optics, based on the assumption that the spot intensity of the SHWS has a Gaussian distribution, which is not applicable to the digital SHWS. In this paper, we present a centroid measurement algorithm based on the adaptive thresholding and dynamic windowing method by utilizing image processing techniques for practical application of the digital SHWS in surface profile measurement. The method can detect the centroid of each focal spot precisely and robustly by eliminating the influence of various noises, such as diffraction of the digital SHWS, unevenness and instability of the light source, as well as deviation between the centroid of the focal spot and the center of the detection area. The experimental results demonstrate that the algorithm has better precision, repeatability, and stability compared with other commonly used centroid methods, such as the statistical averaging, thresholding, and windowing algorithms. PMID:19904304

Yin, Xiaoming; Li, Xiang; Zhao, Liping; Fang, Zhongping

2009-11-10

153

EEG amplitude spectra before near threshold visual presentations differentially predict detection/omission and short-long reaction time outcomes.  

PubMed

Performance in simple stimulus detection manifests as both probability of detection and speed of signaling detected stimuli. These two dimensions of performance across trials were examined with respect to brain states just prior to stimulus delivery, using near threshold stimuli targeting the magnocellular or the parvocellular visual streams in an attempt to isolate differential perceptual preparation. The EEG amplitude of 12 university students was analyzed in spectral bands from 2 to 50 Hz at 9 bilateral channel pairs in a window covering -450 ms to +50 ms relative to stimulus onset. A hierarchical statistical procedure was applied to control false positive results. EEG power in the 2, 4, 8 and 10 Hz bands was found significantly lower at the F7-F8 channel pair both before detected compared to omitted stimuli and before the fastest compared to slowest reaction time quartiles, with no stimulus type effect. In addition, the 22 and 24 Hz band activity was lower prior to better performance frontally (F3-F4, F7-F8) in reaction time but not in detection, while it was larger centro-parietally (CP1-CP2, P3-P4) in detection but not in reaction times. Spectral analysis thus shows stimulus detection and response speed to depend partly on common and partly on distinct pre-stimulus brain states. PMID:23747426

Achim, André; Bouchard, Julie; Braun, Claude M J

2013-06-05

154

Rotationally state-selective photoionization dynamics of molecules at near-threshold photoelectron energies  

SciTech Connect

Rotationally resolved photoelectron spectra can provide significant insight into the underlying dynamics of molecular photoionization. Recent advances in experimental techniques now make it possible to readily achieve rotational resolution in molecular photoelectron spectra. Here we discuss results of our recent theoretical studies of rotationally resolved photoelectron spectra at low and very near-threshold energies for molecules such as HBr, NH, OH, NO, CO, H[sub 2]O, and H[sub 2]S. These studies serve to reveal the rich dynamics of quantum-state specific studies of molecular photoionization and, where possible, provide a robust description of key spectral features of interest in related experimental studies. 42 refs., 10 figs.

Wang, K.; Stephens, J.A.; McKoy, V. (California Inst. of Technology, Pasadena, CA (United States))

1993-09-30

155

Software-based universal demultiplexing: threshold-free energy minimization approach  

NASA Astrophysics Data System (ADS)

Software-based grouping of multiplexed video based on video content, as opposed to the signal generated by multiplexers, is described. The method is based on energy minimization approach. The algorithm automatically determines the amount of multiplexed camera views, and then the frames are grouped with respect to camera views. The algorithm is free of any threshold differences between camera views, and does not depend on the presence of quiet zones. The method also compensates for interference noise, local and global motion, are contrast changes.

Guichard, Frederic; Litz, Alexander; Rudin, Leonid I.; Yu, Ping

2001-02-01

156

The influence of dipole polarisation on threshold displacement energies in UO2  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations of radiation damage in nuclear materials have traditionally been performed using rigid ion empirical potential models. The inclusion of dipole polarisability via the shell model offers the possibility to incorporate more of the underlying physics into simulations of radiation damage via cascade simulations. Here we assess the impact of dipole polarisability on the evolution of radiation damage in UO2 by performing molecular dynamics simulations to determine the threshold displacement energies using both a standard rigid ion potential and the equivalent model including dipole polarisability. The inclusion of dipole polarisability reduces the threshold displacement energies by 20-30% relative to the rigid ion model, suggesting a significant increase in the number of defects created during the collisional phase of the cascade. However, a reduction in the activation energies for migration due to inclusion of polarisability may increase the rate of subsequent interstitial-vacancy recombination. The overall level of radiation damage will, therefore, be determined by the relative effectiveness of these two opposing processes.

Bishop, Clare L.; Murphy, Samuel T.; Rushton, Michael J. D.; Grimes, Robin W.

2012-03-01

157

Thresholds for detection of motion direction during passive lateral whole-body acceleration in normal subjects and patients with bilateral loss of labyrinthine function  

Microsoft Academic Search

To investigate the effect of velocity, acceleration, and gradient of acceleration on self-motion perception, thresholds for detection of direction of whole-body interaural acceleration were determined for various stimulus profiles. For acceleration steps, acceleration thresholds at 67% correct detection of motion direction were similar for eight normals (mean 4.84 cm\\/s2 (range 2.9–6.3), peak gradient = 22 cm\\/s2) and five labyrinthine-defective subjects

C. Gianna; S. Heimbrand; M. Gresty

1996-01-01

158

The Edge Detection of Oil Spills Image Using Self-Adaptive Dynamic Block Threshold Algorithm Based on Non-Maximal Suppression  

Microsoft Academic Search

Edge detection technology of oil spills image on the sea is one of most key technologies to monitor oil spills on the sea. This paper presents a novel method to detect edge of oil spills image on the sea. The algorithm is composed of two parts: nonmaximal suppression realizes candidate edge detection of oil spills image, self-adaptive dynamic block threshold

Yu Jing; Jubai An; Li Li

2009-01-01

159

Pressure and particle motion detection thresholds in fish: a re-examination of salient auditory cues in teleosts.  

PubMed

The auditory evoked potential technique has been used for the past 30 years to evaluate the hearing ability of fish. The resulting audiograms are typically presented in terms of sound pressure (dB re. 1 ?Pa) with the particle motion (dB re. 1 m s(-2)) component largely ignored until recently. When audiograms have been presented in terms of particle acceleration, one of two approaches has been used for stimulus characterisation: measuring the pressure gradient between two hydrophones or using accelerometers. With rare exceptions these values are presented from experiments using a speaker as the stimulus, thus making it impossible to truly separate the contribution of direct particle motion and pressure detection in the response. Here, we compared the particle acceleration and pressure auditory thresholds of three species of fish with differing hearing specialisations, goldfish (Carassius auratus, weberian ossicles), bigeye (Pempheris adspersus, ligamentous hearing specialisation) and a third species with no swim bladder, the common triplefin (Forstergyian lappillum), using three different methods of determining particle acceleration. In terms of particle acceleration, all three fish species have similar hearing thresholds, but when expressed as pressure thresholds goldfish are the most sensitive, followed by bigeye, with triplefin the least sensitive. It is suggested here that all fish have a similar ability to detect the particle motion component of the sound field and it is their ability to transduce the pressure component of the sound field to the inner ear via ancillary hearing structures that provides the differences in hearing ability. Therefore, care is needed in stimuli presentation and measurement when determining hearing ability of fish and when interpreting comparative hearing abilities between species. PMID:22693030

Radford, Craig A; Montgomery, John C; Caiger, Paul; Higgs, Dennis M

2012-06-12

160

Threshold quantum cryptography  

SciTech Connect

We present the concept of threshold collaborative unitary transformation or threshold quantum cryptography, which is a kind of quantum version of threshold cryptography. Threshold quantum cryptography states that classical shared secrets are distributed to several parties and a subset of them, whose number is greater than a threshold, collaborates to compute a quantum cryptographic function, while keeping each share secretly inside each party. The shared secrets are reusable if no cheating is detected. As a concrete example of this concept, we show a distributed protocol (with threshold) of conjugate coding.

Tokunaga, Yuuki [NTT Information Sharing Platform Laboratories, NTT Corporation, 1-1 Hikari-no-oka, Yokosuka, Kanagawa 239-0847 (Japan); Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Okamoto, Tatsuaki [NTT Information Sharing Platform Laboratories, NTT Corporation, 1-1 Hikari-no-oka, Yokosuka, Kanagawa 239-0847 (Japan); Imoto, Nobuyuki [Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

2005-01-01

161

Resummation of threshold, low- and high-energy expansions for heavy-quark correlators  

SciTech Connect

With the help of the Mellin-Barnes transform, we show how to simultaneously resum the expansion of a heavy-quark correlator around q{sup 2}=0 (low-energy), q{sup 2}=4m{sup 2} (threshold, where m is the quark mass), and q{sup 2}{yields}-{infinity} (high-energy) in a systematic way. We exemplify the method for the perturbative vector correlator at O({alpha}{sub s}{sup 2}) and O({alpha}{sub s}{sup 3}). We show that the coefficients, {Omega}(n), of the Taylor expansion of the vacuum polarization function in terms of the conformal variable {omega} admit, for large n, an expansion in powers of 1/n (up to logarithms of n) that we can calculate exactly. This large-n expansion has a sign-alternating component given by the logarithms of the operator-product expansion, and a fixed-sign component given by the logarithms of the threshold expansion in the external momentum q{sup 2}.

Greynat, David [IFAE, Department de Fisica, Universitat Autonoma de Barcelona, 08193 Barcelona (Spain); Peris, Santiago [Grup de Fisica Teorica, Department de Fisica, Universitat Autonoma de Barcelona, 08193 Barcelona (Spain)

2010-08-01

162

Development and Utility of an Internal Threshold Control (ITC) Real-Time PCR Assay for Exogenous DNA Detection  

PubMed Central

Sensitive and specific tests for detecting exogenous DNA molecules are useful for infectious disease diagnosis, gene therapy clinical trial safety, and gene doping surveillance. Taqman real-time PCR using specific sequence probes provides an effective approach to accurately and quantitatively detect exogenous DNA. However, one of the major challenges in these analyses is to eliminate false positive signals caused by either non-targeted exogenous or endogenous DNA sequences, or false negative signals caused by impurities that inhibit PCR. Although multiplex Taqman PCR assays have been applied to address these problems by adding extra primer-probe sets targeted to endogenous DNA sequences, the differences between targets can lead to different detection efficiencies. To avoid these complications, a Taqman PCR-based approach that incorporates an internal threshold control (ITC) has been developed. In this single reaction format, the target sequence and ITC template are co-amplified by the same primers, but are detected by different probes each with a unique fluorescent dye. Sample DNA, a prescribed number of ITC template molecules set near the limit of sensitivity, a single pair of primers, target probe and ITC probe are added to one reaction. Fluorescence emission signals are obtained simultaneously to determine the cycle thresholds (Ct) for amplification of the target and ITC sequences. The comparison of the target Ct with the ITC Ct indicates if a sample is a true positive for the target (i.e. Ct less than or equal to the ITC Ct) or negative (i.e. Ct greater than the ITC Ct). The utility of this approach was demonstrated in a nonhuman primate model of rAAV vector mediated gene doping in vivo and in human genomic DNA spiked with plasmid DNA.

Ni, Weiyi; Le Guiner, Caroline; Moullier, Philippe; Snyder, Richard O.

2012-01-01

163

Dynamics of strangeness production in heavy-ion collisions near threshold energies  

SciTech Connect

Within the framework of the improved isospin-dependent quantum molecular dynamics (ImIQMD) model, the dynamics of strangeness (K{sup 0,+}, {Lambda}, and {Sigma}{sup -,0,+}) production in heavy-ion collisions near threshold energies is investigated systematically, with the strange particles considered to be produced mainly by inelastic collisions of baryon-baryon and pion-baryon. Collisions in the region of suprasaturation densities of the dense baryonic matter formed in heavy-ion collisions dominate the yields of strangeness production. Total multiplicities as functions of incident energies and collision centralities are calculated with the Skyrme parameter SLy6. The excitation function of strangeness production is analyzed and also compared with the KaoS data for K{sup +} production in the reactions {sup 12}C+{sup 12}C and {sup 197}Au+{sup 197}Au.

Feng Zhaoqing; Jin Genming [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2010-11-15

164

Why longer song elements are easier to detect: threshold level-duration functions in the Great Tit and comparison with human data.  

PubMed

Our study estimates detection thresholds for tones of different durations and frequencies in Great Tits (Parus major) with operant procedures. We employ signals covering the duration and frequency range of communication signals of this species (40-1,010 ms; 2, 4, 6.3 kHz), and we measure threshold level-duration (TLD) function (relating threshold level to signal duration) in silence as well as under behaviorally relevant environmental noise conditions (urban noise, woodland noise). Detection thresholds decreased with increasing signal duration. Thresholds at any given duration were a function of signal frequency and were elevated in background noise, but the shape of Great Tit TLD functions was independent of signal frequency and background condition. To enable comparisons of our Great Tit data to those from other species, TLD functions were first fitted with a traditional leaky-integrator model. We then applied a probabilistic model to interpret the trade-off between signal amplitude and duration at threshold. Great Tit TLD functions exhibit features that are similar across species. The current results, however, cannot explain why Great Tits in noisy urban environments produce shorter song elements or faster songs than those in quieter woodland environments, as detection thresholds are lower for longer elements also under noisy conditions. PMID:23338560

Pohl, Nina U; Slabbekoorn, Hans; Neubauer, Heinrich; Heil, Peter; Klump, Georg M; Langemann, Ulrike

2013-01-22

165

Low-threshold 2-micron holmium laser excited by nonradiative energy transfer from Fe(3+) in YGG  

NASA Astrophysics Data System (ADS)

Low-threshold operation of a 2.09-micron holmium laser, excited by nonradiative energy transfer from trivalent iron, has been demonstrated. With a 1.45-mm-thick crystal of Fe,Ho:YGG at 77 K, absorbed power thresholds between 5 and 8 mW were observed as the pump wavelength was continuously tuned from 0.92 to 0.97 micron.

Dixon, G. J.; Johnson, L. F.

1992-12-01

166

Low-threshold 2-microm holmium laser excited by nonradiative energy transfer from Fe(3+) in YGG.  

PubMed

Low-threshold operation of a 2.09-microm holmium laser, excited by nonradiative energy transfer from trivalent iron, has been demonstrated. With a 1.45-mm-thick crystal of Fe,Ho:YGG at 77 K, absorbed power thresholds between 5 and 8 mW were observed as the pump wavelength was continuously tuned from 0.92 to 0.97 microm. PMID:19798315

Dixon, G J; Johnson, L F

1992-12-15

167

Low-threshold 2-micron holmium laser excited by nonradiative energy transfer from Fe(3+) in YGG  

Microsoft Academic Search

Low-threshold operation of a 2.09-micron holmium laser, excited by nonradiative energy transfer from trivalent iron, has been demonstrated. With a 1.45-mm-thick crystal of Fe,Ho:YGG at 77 K, absorbed power thresholds between 5 and 8 mW were observed as the pump wavelength was continuously tuned from 0.92 to 0.97 micron.

G. J. Dixon; L. F. Johnson

1992-01-01

168

Potential energy threshold of surface erosion on GaN by impact of slow highly charged heavy ions  

Microsoft Academic Search

In the present work the erosion behavior on the surface of GaN epi-layer by the impact of various slow highly charged heavy ions (SHCIs, including Arq+, Xeq+ and Pbq+, in two incidence geometries) was investigated. Atomic force microscopy reveals a well-defined threshold of potential energy carried by the incident heavy ions accounting for the surface erosion. This threshold also depends

L. Q. Zhang; C. H. Zhang; Y. T. Yang; L. H. Han; B. S. Li; S. J. Song; Y. M. Sun; Y. F. Jin

2011-01-01

169

Maximizing allele detection: Effects of analytical threshold and DNA levels on rates of allele and locus drop-out.  

PubMed

Interpretation of DNA evidence depends upon the ability of the analyst to accurately compare the DNA profile obtained from an item of evidence and the DNA profile of a standard. This interpretation becomes progressively more difficult as the number of 'drop-out' and 'drop-in' events increase. Analytical thresholds (AT) are typically selected to ensure the false detection of noise is minimized. However, there exists a tradeoff between the erroneous labeling of noise as alleles and the false non-detection of alleles (i.e. drop-out). In this study, the effect ATs had on both types of error was characterized. Various ATs were tested, where three relied upon the analysis of baseline signals obtained from 31 negative samples. The fourth AT was determined by utilizing the relationship between RFU signal and DNA input. The other ATs were the commonly employed 50, 150 and 200 RFU thresholds. Receiver Operating Characteristic (ROC) plots showed that although high ATs completely negated the false labeling of noise, DNA analyzed with ATs derived using analysis of the baseline signal exhibited the lowest rates of drop-out and the lowest total error rates. In another experiment, the effect small changes in ATs had on drop-out was examined. This study showed that as the AT increased from ?10 to 60 RFU, the number of heterozygous loci exhibiting the loss of one allele increased. Between ATs of 60 and 150 RFU, the frequency of allelic drop-out remained constant at 0.27 (±0.02) and began to decrease when ATs of 150 RFU or greater were utilized. In contrast, the frequency of heterozygous loci exhibiting the loss of both alleles consistently increased with AT. In summary, for samples amplified with less than 0.5ng of DNA, ATs derived from baseline analysis of negatives were shown to decrease the frequency of drop-out by a factor of 100 without significantly increasing rates of erroneous noise detection. PMID:22796031

Rakay, Christine A; Bregu, Joli; Grgicak, Catherine M

2012-07-12

170

Toward perpetual wireless networks: Opportunistic large arrays with transmission thresholds and energy harvesting  

NASA Astrophysics Data System (ADS)

Solving the key issue of sustainability of battery-powered sensors continues to attract significant research attention. The prevailing theme of this research is to address this concern using energy-efficient protocols based on a form of simple cooperative transmission (CT) called the opportunistic large arrays (OLAs), and intelligent exploitation of energy harvesting and hybrid energy storage systems (HESSs). The two key contributions of this research, namely, OLA with transmission threshold (OLA-T) and alternating OLA-T (A-OLA-T), offer an signal-to-noise ratio (SNR) advantage (i.e., benefits of diversity and array (power) gains) in a multi-path fading environment, thereby reducing transmit powers or extending range. Because these protocols do not address nodes individually, the network overhead remains constant for high density networks or nodes with mobility. During broadcasting across energy-constrained networks, while OLA-T saves energy by limiting node participation within a single broadcast, A-OLA-T optimizes over multiple broadcasts and drains the nodes in an equitable fashion. A major bottleneck for network sustainability is the ability of a rechargeable battery (RB) to store energy, which is limited by the number of charge-discharge cycles. Energy harvesting using a HESS that comprises a RB and a supercapacitor (SC) will minimize the RB usage, thereby preserving the charge-discharge cycles. Studying the HESS is important, rather than the SC-alone because while an SC with harvested energy may be sufficient for routine monitoring, if there is an alert, the RB could be used as necessary to support the heavier reporting requirements. Therefore, another key contribution of this research is the design and analysis of a novel routing metric called communications using HESS (CHESS), which extends the RB-life by relaying exclusively with SC energy.

Kailas, Aravind

171

Optimized state-independent entanglement detection based on a geometrical threshold criterion  

NASA Astrophysics Data System (ADS)

Experimental procedures are presented for the rapid detection of entanglement of unknown arbitrary quantum states. The methods are based on the entanglement criterion using accessible correlations and the principle of correlation complementarity. Our first scheme essentially establishes the Schmidt decomposition for pure states, with few measurements only and without the need for shared reference frames. The second scheme employs a decision tree to speed up entanglement detection. We analyze the performance of the methods using numerical simulations and verify them experimentally for various states of two, three, and four qubits.

Laskowski, Wies?aw; Schwemmer, Christian; Richart, Daniel; Knips, Lukas; Paterek, Tomasz; Weinfurter, Harald

2013-08-01

172

On-orbit Performance and Detection Thresholds for LORAAS from Stellar Observations  

NASA Astrophysics Data System (ADS)

In February of 1999, the US Air Force Space Test Program launched the Advanced Research and Global Observations Satellite (ARGOS) into an 830 km altitude, near-polar sun-synchronous orbit with a 14:30 ascending node local time. Aboard the ARGOS satellite is a suite of remote-sensing instruments that measure density, composition, and temperature of the thermosphere and ionosphere. The Low Resolution Airglow and Auroral Spectrograph (LORAAS) monitors upper atmospheric airglow in the far-ultraviolet and extreme-ultraviolet passband. LORAAS is identical to the Special Sensor Ultraviolet Limb Imager (SSULI) sensor whose mission will be starting with the launch of the next Defense Meteorological Satellite Program (DMSP) satellite and continuing on the next four DMSP satellites. Limb scans, atmospheric radiance profiles, in the satellite's orbital plane are collected every ninety seconds. Due to the expected decrease as a function of time in the sensitivity of the instrument, high voltage increases have been performed throughout the mission to increase the gain on the microchannel plates. The main objective of this study focuses on the need to observe the threshold at which LORAAS is no longer able to observe nightside mid-latitude electron densities. It is necessary to compute the changing sensitivity of LORAAS by making an identification of stars as they pass through the field of view of the instrument and measuring the instrument response as a function of time. The establishment of a sensitivity curve for the lifetime of the mission is useful knowledge both to the UV inversion and to characterize the behavior of the SSULI instrument.

Henderlight, E.; Thonnard, S.; Dymond, K.; Nicholas, A.; Budzien, S.; McDonald, S.; McCoy, R.

2003-04-01

173

Different Thresholds for Detection and Discrimination of Odors in the Honey bee (Apis mellifera)  

Microsoft Academic Search

Naturally occurring odors used by animals for mate recognition, food identification and other purposes must be detected at concentrations that vary across several orders of magnitude. Olfactory systems must therefore have the capacity to represent odors over a large range of concentrations regardless of dramatic changes in the salience, or perceived intensity, of a stimulus. The stability of the representation

Geraldine A. Wright; Brian H. Smith

2004-01-01

174

Acetic acid detection threshold in synthetic wine samples of a portable electronic nose.  

PubMed

Wine quality is related to its intrinsic visual, taste, or aroma characteristics and is reflected in the price paid for that wine. One of the most important wine faults is the excessive concentration of acetic acid which can cause a wine to take on vinegar aromas and reduce its varietal character. Thereby it is very important for the wine industry to have methods, like electronic noses, for real-time monitoring the excessive concentration of acetic acid in wines. However, aroma characterization of alcoholic beverages with sensor array electronic noses is a difficult challenge due to the masking effect of ethanol. In this work, in order to detect the presence of acetic acid in synthetic wine samples (aqueous ethanol solution at 10% v/v) we use a detection unit which consists of a commercial electronic nose and a HSS32 auto sampler, in combination with a neural network classifier (MLP). To find the characteristic vector representative of the sample that we want to classify, first we select the sensors, and the section of the sensors response curves, where the probability of detecting the presence of acetic acid will be higher, and then we apply Principal Component Analysis (PCA) such that each sensor response curve is represented by the coefficients of its first principal components. Results show that the PEN3 electronic nose is able to detect and discriminate wine samples doped with acetic acid in concentrations equal or greater than 2 g/L. PMID:23262483

Macías, Miguel Macías; Manso, Antonio García; Orellana, Carlos Javier García; Velasco, Horacio Manuel González; Caballero, Ramón Gallardo; Chamizo, Juan Carlos Peguero

2012-12-24

175

Acetic Acid Detection Threshold in Synthetic Wine Samples of a Portable Electronic Nose  

PubMed Central

Wine quality is related to its intrinsic visual, taste, or aroma characteristics and is reflected in the price paid for that wine. One of the most important wine faults is the excessive concentration of acetic acid which can cause a wine to take on vinegar aromas and reduce its varietal character. Thereby it is very important for the wine industry to have methods, like electronic noses, for real-time monitoring the excessive concentration of acetic acid in wines. However, aroma characterization of alcoholic beverages with sensor array electronic noses is a difficult challenge due to the masking effect of ethanol. In this work, in order to detect the presence of acetic acid in synthetic wine samples (aqueous ethanol solution at 10% v/v) we use a detection unit which consists of a commercial electronic nose and a HSS32 auto sampler, in combination with a neural network classifier (MLP). To find the characteristic vector representative of the sample that we want to classify, first we select the sensors, and the section of the sensors response curves, where the probability of detecting the presence of acetic acid will be higher, and then we apply Principal Component Analysis (PCA) such that each sensor response curve is represented by the coefficients of its first principal components. Results show that the PEN3 electronic nose is able to detect and discriminate wine samples doped with acetic acid in concentrations equal or greater than 2 g/L.

Macias, Miguel Macias; Manso, Antonio Garcia; Orellana, Carlos Javier Garcia; Velasco, Horacio Manuel Gonzalez; Caballero, Ramon Gallardo; Chamizo, Juan Carlos Peguero

2013-01-01

176

Establishing the detection threshold for Bacillus subtilis in a complex matrix using an inorganic fingerprint approach.  

PubMed

Methods for the detection and characterization of airborne biological warfare agents, such as bacteria, using their DNA or organic composition are fairly well developed. This approach is useful for identifying the type of bacterial strain once the organism has been isolated from the matrix sampled (e.g., dust particles) and can identify genetically related organisms, which might be helpful during a forensic investigation. However, this genetic signature will not reveal information related to the methods used to grow and weaponize the organism. Bacteria will take on an inorganic signature that is related to their growth and processing history. Therefore, the ability to characterize the inorganic fingerprint of a biological particle has the potential to detect the presence of a bio-agent and expand the forensic tools available to those investigating the origin of biological weapons. This investigation builds on previous work documenting the usefulness of the inorganic fingerprint and evaluates the limits of detection in the presence of background dust. Based on ICP-MS measurements and mixing models of digested mixtures of laboratory cultured Bacillus subtilis (anthrax stimulant) and NIST Standard Reference Material 2709 (dust stimulant), the inorganic fingerprint method is capable of detecting toxicologically relevant levels of a bio-warfare agent in the presence of a complex background matrix. PMID:21872011

Lev, S M; Gasparich, G; Choi, F; King, L; Moore, J; Zimmerman, S

2011-07-03

177

Description of a new all cause mortality surveillance system in Sweden as a warning system using threshold detection algorithms.  

PubMed

A warning system has been set up to detect unusual weekly clusters of deaths by age group and municipality using all-cause Swedish death registry data. The technique for monitoring deaths by age group (<1, 1-24, 25-44, 45-64 and 65 plus) and week uses a compound smoothing technique, which calculates a baseline of expected events from retrospective data. Due to insufficient baseline data for the geographical component of the system a different algorithm, based on the Poisson distribution, was chosen to calculate expected weekly number of deaths per municipality, adjusting for municipalities with inherently higher mortality rates. This system was designed and tested during 2004 and implemented from the beginning of 2005. Threshold settings have been adjusted to provide a realistic number of weekly alerts. An evaluation of the system will be performed prospectively from the beginning of 2005 due to the lack of a gold standard for retrospective performance evaluation. PMID:16547832

Sartorius, B; Jacobsen, H; Törner, A; Giesecke, J

2006-01-01

178

Energy threshold for the creation of nanodots on SrTiO3 by swift heavy ions  

NASA Astrophysics Data System (ADS)

We present experimental and theoretical data on the threshold behaviour of nanodot creation with swift heavy ions. A model calculation based on a two-temperature model that takes into account the spatially resolved electron density gives a threshold of 12 keV nm-1 below which the energy density at the end of the track is no longer high enough to melt the material. In the corresponding experiments, we irradiated SrTiO3 surfaces under grazing incidence with swift heavy ions. The resulting chains of nanodots were analysed by atomic force microscopy (AFM). In addition, some samples of SrTiO3 irradiated under normal incidence were analysed by transmission electron microscopy (TEM). Both experiments showed two thresholds, which were connected with the appearance of tracks and the creation of fully developed tracks. The threshold values were similar for surface and bulk tracks, suggesting that the same processes occur at both glancing and normal incidence.

Karlusi?, Marko; Akcöltekin, Sevilay; Osmani, Orkhan; Monnet, Isabelle; Lebius, Henning; Jaksi?, Milko; Schleberger, Marika

2010-04-01

179

Multi-Threshold Threshold Elements  

Microsoft Academic Search

A multi-threshold element is one in which several thresholds are used to separate the true inputs from the false inputs. Many circuit elements and configurations can be described by this model. An approach, based on conventional single-threshold threshold elements, is developed for the analysis and synthesis of multithreshold threshold elements. It is shown that the basic properties of such elements

Donald R. Haring

1966-01-01

180

Robust model-based detection of the lung field boundaries in portable chest radiographs supported by selective thresholding  

NASA Astrophysics Data System (ADS)

Portable chest radiography is a valuable tool for screening patients hospitalized in intensive care, providing visual cues for diagnosis and physiological measurements. However, its practicality comes at the cost of quality, which is mainly affected by misaligned body positioning, thus increasing x-ray misinterpretation rates. This paper presents a novel methodology for the detection of the lung field boundaries in portable chest radiographs of patients with bacterial pulmonary infections. Such infections are radiographically manifested as foci of consolidations which can lead to vague or invisible lung field boundaries, difficult to distinguish even by experienced physicians. Conventional and state-of-the-art approaches address mainly stationary radiographs, whereas only a few of them cope with pulmonary infections. The proposed methodology is based on an active shape model incorporating shape prior information about the lung fields. The model is initialized by a novel technique utilizing a set of salient points detected on the peripheral anatomic structures of the lungs. A selective thresholding algorithm based on a spinal cord sampling process supports both the initialization and the evolution of the model for the detection of the lung field boundaries. The experiments show that the proposed methodology outperforms state-of-the-art approaches.

Iakovidis, D. K.; Savelonas, M. A.; Papamichalis, G.

2009-10-01

181

Inclusive neutrino scattering off deuteron from threshold to GeV energies  

SciTech Connect

Cross sections for inclusive neutrino scattering off deuteron induced by neutral and charge-changing weak currents are calculated from threshold up to GeV energies, using the Argonne v{sub 18} potential and consistent nuclear electroweak currents with one- and two-body terms. Two-body contributions are found to be small, and increase the cross sections obtained with one-body currents by less than 10% over the whole range of energies. Total cross sections obtained by describing the final two-nucleon states with plane waves differ negligibly, for neutrino energies {approx}> 500 MeV, from those in which interaction effects in these states are fully accounted for. The sensitivity of the calculated cross sections to different models for the two-nucleon potential and/or two-body terms in the weak current is found to be weak. In order to illustrate nuclear structure effects, the cross sections are compared to those obtained in a naive model in which the deuteron is taken to consist of a free proton and neutron at rest.

Gang Shen, Laura E. Marcucci, Joseph Carlson, Stefano Gandolfi, Rocco Schiavilla

2012-09-01

182

Non-human primate skull effects on the cavitation detection threshold of FUS-induced blood-brain barrier opening  

NASA Astrophysics Data System (ADS)

Microbubble (MB)-assisted focused ultrasound is a promising technique for delivering drugs to the brain by noninvasively and transiently opening the blood-brain barrier (BBB), and monitoring BBB opening using passive cavitation detection (PCD) is critical in detecting its occurrence, extent as well as assessing its mechanism. One of the main obstacles in achieving those objectives in large animals is the transcranial attenuation. To study the effects, the cavitation response through the in-vitro non-human primate (NHP) skull was investigated. In-house manufactured lipid-shelled MB (medium diameter: 4-5 um) were injected into a 4-mm channel of a phantom below a degassed monkey skull. A hydrophone confocally aligned with the FUS transducer served as PCD during sonication (frequency: 0.50 MHz, peak rarefactional pressures: 0.05-0.60 MPa, pulse length: 100 cycles, PRF: 10 Hz, duration: 2 s) for four cases: water without skull, water with skull, MB without skull and MB with skull. A 5.1-MHz linear-array transducer was also used to monitor the MB disruption. The frequency spectra, spectrograms, stable cavitation dose (SCD) and inertial cavitation dose (ICD) were quantified. Results showed that the onset of stable cavitation and inertial cavitation in the experiments occurred at 50 kPa, and was detectable throught the NHP skull since the both the detection thresholds for stable cavitation and inertial cavitation remained unchanged compared to the non-skull case, and the SCD and ICD acquired transcranially may not adequately represent the true extent of stable and inertial cavitation due to the skull attenuation.

Wu, Shih-Ying; Tung, Yao-Sheng; Marquet, Fabrice; Chen, Cherry C.; Konofagou, Elisa E.

2012-11-01

183

Energy dependence of electron damage and displacement threshold energy in 6H silicon carbide  

Microsoft Academic Search

The frequency response of silicon carbide (SiC) light-emitting diodes has been used to measure the energy dependence of displacement damage produced in 6H SiC by energetic electrons. The minimum electron energy required to produce displacement damage was determined to be 108±7 keV, corresponding to an atomic displacement of silicon atoms. For electrons of energies greater than 0.5 MeV, the damage

A. L. Barry; B. Lehmann; D. Fritsch; D. Braeunig

1991-01-01

184

Inclusive neutrino scattering off the deuteron from threshold to GeV energies  

NASA Astrophysics Data System (ADS)

Background: Neutrino-nucleus quasi-elastic scattering is crucial to interpret the neutrino oscillation results in long baseline neutrino experiments. There are rather large uncertainties in the cross section, due to insufficient knowledge on the role of two-body weak currents.Purpose: Determine the role of two-body weak currents in neutrino-deuteron quasi-elastic scattering up to GeV energies.Methods: Calculate cross sections for inclusive neutrino scattering off deuteron induced by neutral and charge-changing weak currents, from threshold up to GeV energies, using the Argonne v18 potential and consistent nuclear electroweak currents with one- and two-body terms.Results: Two-body contributions are found to be small, and increase the cross sections obtained with one-body currents by less than 10% over the whole range of energies. Total cross sections obtained by describing the final two-nucleon states with plane waves differ negligibly, for neutrino energies ? MeV, from those in which interaction effects in these states are fully accounted for. The sensitivity of the calculated cross sections to different models for the two-nucleon potential and/or two-body terms in the weak current is found to be weak. Comparing cross sections to those obtained in a naive model in which the deuteron is taken to consist of a free proton and neutron at rest, nuclear structure effects are illustrated to be non-negligible.Conclusion: Contributions of two-body currents in neutrino-deuteron quasi-elastic scattering up to GeV are found to be smaller than 10%. Finally, it should be stressed that the results reported in this work do not include pion production channels.

Shen, G.; Marcucci, L. E.; Carlson, J.; Gandolfi, S.; Schiavilla, R.

2012-09-01

185

Remarks on detecting high-energy deuterium–tritium fusion gamma rays using a gas Cherenkov detector  

Microsoft Academic Search

As fusion ignition conditions are approached using the national ignition facility (NIF), independent high-bandwidth gamma-ray fusion burn measurements become essential complements to information obtained from neutron diagnostics. The 16.75-MeV gamma rays that accompany deuterium–tritium (d+t) fusion can be detected using a high-bandwidth gaseous carbon dioxide Cherenkov threshold detector. The detection energy threshold was set by the CO2 gas pressure. A

J. M. Mack; R. R. Berggren; S. E. Caldwell; C. R. Christensen; S. C. Evans; J. R. Faulkner Jr.; R. L. Griffith; G. M. Hale; R. S. King; D. K. Lash; R. A. Lerche; J. A. Oertel; D. M. Pacheco; C. S. Young

2006-01-01

186

Energy dependence of electron damage and displacement threshold energy in 6H silicon carbide  

NASA Astrophysics Data System (ADS)

The frequency response of silicon carbide (SiC) light-emitting diodes has been used to measure the energy dependence of displacement damage produced in 6H SiC by energetic electrons. The minimum electron energy required to produce displacement damage was determined to be 108 +/- 7 keV, corresponding to an atomic displacement of silicon atoms. For electrons of energies greater than 0.5 MeV, the damage constant for lifetime degradation in SiC is lower than that for GaAs by more than three orders of magnitude, indicating a greatly superior resistance of SiC to displacement damage in most radiation environments.

Barry, A. L.; Lehmann, B.; Fritsch, D.; Braeunig, D.

1991-12-01

187

Thresholds for igniting exothermic reactions in Al/Ni multilayers using pulses of electrical, mechanical, and thermal energy  

NASA Astrophysics Data System (ADS)

We use pulses of electrical, mechanical, and thermal energy to determine the ignition thresholds of self-propagating reactions in Al/(Ni-7 V) and Al/Inconel multilayers. The energy density and power density required to initiate reactions in a Al/(Ni-7 V) foil with a 50 nm bilayer is compared for all three techniques to demonstrate the importance of heat loss on ignition thresholds and its dependence on the test volume and the surrounding thermal resistance. In addition, ignition is shown to occur at temperatures as low as 232 °C when heat losses are very small suggesting that ignition can be controlled by atomic mixing in the solid state. The experiments demonstrate that the ignition threshold drops with increasing ignition volume, and it rises with increasing bilayer spacing and with increasing intermixed thickness. These trends are also supported by an analytical model we derive to predict the effects of ignition volume, multilayer microstructure, and physical properties on the ignition threshold. We calculate an activation energy of 77.3 +/- 1.3 kJ/mol for solid state mixing based on measured ignition temperatures.

Fritz, Gregory M.; Spey, Stephen J.; Grapes, Michael D.; Weihs, Timothy P.

2013-01-01

188

Energy Detection Based Estimation of Channel Occupancy Rate with Adaptive Noise Estimation  

NASA Astrophysics Data System (ADS)

Recently, there has been growing interest in opportunistically utilizing the 2.4GHz ISM-band. Numerous spectrum occupancy measurements covering the ISM-band have been performed to analyze the spectrum usage. However, in these campaigns the verification of the correctness of the obtained occupancy values for the highly dynamic ISM-band has not been presented. In this paper, we propose and verify channel occupancy rate (COR) estimation utilizing energy detection mechanism with a novel adaptive energy detection threshold setting method. The results are compared with the true reference COR values. Several different types of verification measurements showed that our setup can estimate the COR values of 802.11 traffic well, with negligible overestimation. The results from real-time real-life measurements also confirm that the proposed adaptive threshold setting method enables accurate thresholds even in the situations where multiple interferers are present in the received signal.

Lehtomäki, Janne J.; Vuohtoniemi, Risto; Umebayashi, Kenta; Mäkelä, Juha-Pekka

189

Quantitative encoding of a partial agonist effect on individual opioid receptors by multi-site phosphorylation and threshold detection  

PubMed Central

Many drugs act as partial agonists of seven-transmembrane signaling receptors when compared to endogenous ligands. Partial agonism is well described as a 'macroscopic' property manifest at the level of physiological systems or cell populations, but it is not known whether partial agonists encode discrete regulatory information at the 'microscopic' level of individual receptors. We addressed this question by focusing on morphine, a partial agonist drug for µ-type opioid peptide receptors, and combining quantitative mass spectrometry with cell biological analysis to investigate morphine's reduced efficacy for promoting receptor endocytosis when compared to a peptide full agonist. We show that these chemically distinct ligands produce a complex, and qualitatively similar mixture of phosphorylated opioid receptor forms in intact cells. Quantitatively, however, the agonists promote markedly disproportional production of multi-site phosphorylation involving a specific Ser/Thr motif, whose modification at more than one residue is essential for efficient recruitment of the adaptor protein ?-arrestin to clathrin-coated pits that mediate subsequent endocytosis of MORs. These results reveal quantitative encoding of agonist-selective endocytosis at the level of individual opioid receptors, based on the conserved biochemical principles of multi-site phosphorylation and threshold detection.

Lau, Elaine K.; Trester-Zedlitz, Michelle; Trinidad, Jonathan C.; Kotowski, Sarah J.; Krutchinsky, Andrew N.; Burlingame, Alma L.; von Zastrow, Mark

2013-01-01

190

Automated threshold detection for auditory brainstem responses: comparison with visual estimation in a stem cell transplantation study  

Microsoft Academic Search

BACKGROUND: Auditory brainstem responses (ABRs) are used to study auditory acuity in animal-based medical research. ABRs are evoked by acoustic stimuli, and consist of an electrical signal resulting from summated activity in the auditory nerve and brainstem nuclei. ABR analysis determines the sound intensity at which a neural response first appears (hearing threshold). Traditionally, threshold has been assessed by visual

Sofie Bogaerts; John D Clements; Jeremy M Sullivan; Sharon Oleskevich

2009-01-01

191

The 13C(P,N)13N Reaction Threshold.  

National Technical Information Service (NTIS)

The Carbon-13 proton-neutron reaction was investigated in an energy range close to threshold using a long counter for detecting the neutrons. An excitation curve at 0 deg. was measured from threshold (3.237 MeV) to 3.85 MeV. Angular distributions were obt...

O. Dietzsch

1966-01-01

192

Threshold cryptosystems  

Microsoft Academic Search

Often the power to use a cryptosystem has to be shared. In threshold schemes, t-out-of-l have the power to regenerate a secret key (while less than t have not). However threshold schemes cannot be used directly in many applications, such as threshold signatures in which t-out-of-l have to co-sign a message. A normal threshold scheme would require the shareholders to

Yvo Desmedt

193

Energy-dependent photoelectron angular distributions of two-color two-photon above threshold ionization of atomic helium  

SciTech Connect

Energy-dependent photoelectron angular distributions from two-color two-photon above threshold ionizations are investigated to determine the partial-wave characteristics of free-free electronic transitions in helium. Sideband photoelectron energies ranging from 0.18 to 13.0 eV are measured with different wavelengths of the perturbative infrared dressing field as well as different individually selected high-order harmonics. Using the experimentally measured cross-section ratios and anisotropy parameters together with analytical expressions derived from second-order perturbation theory, the partial-wave branching fractions going to the S and D waves in the positive and negative sidebands are determined as a function of photoelectron kinetic energy. The results provide a sensitive test for theoretical models of two-color two-photon above threshold ionization in atoms and molecules.

Haber, Louis H.; Doughty, Benjamin; Leone, Stephen R. [Departments of Chemistry and Physics, and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

2011-07-15

194

Efficiency of BRCAPRO and Myriad II mutation probability thresholds versus cancer history criteria alone for BRCA1/2 mutation detection  

PubMed Central

Considerable differences exist amongst countries in the mutation probability methods and thresholds used to select patients for BRCA1/2 genetic screening. In order to assess the added value of mutation probability methods, we have retrospectively calculated the BRCAPRO and Myriad II probabilities in 306 probands who had previously been selected for DNA-analysis according to criteria based on familial history of cancer. DNA-analysis identified 52 mutations (16.9%) and 11 unclassified variants (UVs, 3.6%). Compared to cancer history, a threshold ?10% with BRCAPRO or with Myriad II excluded about 40% of the patients from analysis, including four with a mutation and probabilities <10% with both programs. All four probands had a BRCA2 mutation. BRCAPRO and Myriad II showed similar specificity at 10% threshold, overall BRCAPRO was more sensitive than Myriad II for the detection of mutations. Only two of the probands with an UV had probabilities >20% with BRCAPRO and Myriad II. In summary, BRCAPRO and Myriad II are more efficient than cancer history alone to exclude patients without a mutation. BRCAPRO performs better for the detection of BRCA1 mutations than of BRCA2 mutations. The Myriad II scores provided no additional information than the BRCAPRO scores alone for the detection of patients with a mutation. The use of thresholds excluded from analysis the majority of patients carrying an UV.

van Harssel, J. J. T.; van Roozendaal, C. E. P.; Detisch, Y.; Brandao, R. D.; Paulussen, A. D. C.; Zeegers, M.; Blok, M. J.

2009-01-01

195

Experimental Evidence of Threshold Effects in the Energy Loss of Protons in Carbon and Aluminum due to Inner Shell Ionization  

NASA Astrophysics Data System (ADS)

We explore the contributions of inner shell ionization to the energy loss of 7 to 270 keV protons in C and Al foils under experimental conditions such that the product of the observation angle and the projectile energy is kept constant. By normalizing these energy loss measurements to the energy loss in the forward direction we observe a pronounced rising behavior with increasing energy. This effect appears in the same range of energies where the respective K- and L-shell ionization cross sections of these elements show a similar threshold behavior. Based also on various theoretical considerations we interpret these results as clear evidence of the inner shell ionization contribution to the energy loss.

Famá, M.; Eckardt, J. C.; Lantschner, G. H.; Arista, N. R.

2000-11-01

196

Adaptive Local Thresholding by Verification-Based Multithreshold Probing with Application to Vessel Detection in Retinal Images  

Microsoft Academic Search

In this paper, we propose a general framework of adaptive local thresholding based on a verification-based multithreshold probing scheme. Object hypotheses are generated by binarization using hypothetic thresholds and accepted\\/rejected by a verification procedure. The application-dependent verification procedure can be designed to fully utilize all relevant informations about the objects of interest. In this sense, our approach is regarded as

Xiaoyi Jiang; Daniel Mojon

2003-01-01

197

Influence of high pressure on the threshold displacement energies in silicon carbide: A Car-Parrinello molecular dynamics approach  

NASA Astrophysics Data System (ADS)

The threshold displacement energies in silicon carbide under different pressures are determined with ab initio molecular dynamics. The results show that the threshold displacement energies change anisotropically in different crystallographic directions when high pressure is applied. However, the weighted average values for both the C and Si sublattice, which determine the defect production in a material under irradiation, are found to increase significantly with increasing external pressures. Besides, we have observed some new defect structures under high pressures which are not observed at ambient conditions. Our results show that irradiation under high pressures could decrease the production rate of point defects in SiC, thus greatly enhancing its resistivity against radiation damage. The combination of irradiation and high pressure technique hence provides a pathway to obtain new structure materials.

Zhao, Shijun; Xue, Jianming; Lan, Chune; Sun, Lixin; Wang, Yugang; Yan, Sha

2012-09-01

198

Measurement of Inclusive Radiative B-Meson Decays with a Photon Energy Threshold of 1.7 GeV  

SciTech Connect

Using 605 fb{sup -1} of data collected at the UPSILON(4S) resonance we present a measurement of the inclusive radiative B-meson decay channel, B->X{sub s}gamma. For the lower photon energy thresholds of 1.7, 1.8, 1.9, and 2.0 GeV, as defined in the rest frame of the B meson, we measure the partial branching fraction and the mean and variance of the photon energy spectrum. At the 1.7 GeV threshold we obtain the partial branching fraction BF(B->X{sub s}gamma)=(3.45+-0.15+-0.40)x10{sup -4}, where the errors are statistical and systematic.

Limosani, A.; Barberio, E.; Julius, T.; Sevior, M. E.; Taylor, G. N.; Urquijo, P.; Wedd, R. [University of Melbourne, School of Physics, Victoria 3010 (Australia); Aihara, H. [Department of Physics, University of Tokyo, Tokyo (Japan); Arinstein, K.; Bondar, A.; Eidelman, S.; Shebalin, V. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Aushev, T. [Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Bakich, A. M.; Varvell, K. E.; Yabsley, B. D. [University of Sydney, Sydney, New South Wales (Australia); Balagura, V.; Danilov, M.; Liventsev, D.; Mizuk, R. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation)

2009-12-11

199

Resonances and Threshold Phenomena in Low-Energy Electron Collisions with Hydrogen Halides: New Experimental and Theoretical Results  

NASA Astrophysics Data System (ADS)

Low-energy electron collisions with HCl and HBr and the deuterated compounds have been investigated by experimental and theoretical methods. New experimental results have been obtained on relative differential cross-sections for vibrational excitation and dissociative electron attachment. Measurements with high energy resolution for rotationally cooled molecules have revealed, in addition to shape resonance, threshold peaks and Wigner cusps, the existence of surprisingly sharp oscillatory structures in the elastic and v = 0 1 vibrational excitation cross-sections in a narrow range below the dissociative attachment threshold. The theoretical analysis is based on an improved nonlocal resonance model which has been constructed on the basis of ab initio fixed-nuclei scattering phase shifts for HCl and HBr and accurate ab initio calculations of the bound part of the HCl- and HBr- potential-energy functions. The high degree of agreement which has been obtained between experiment and theory for all channels indicates that the mechanisms responsible for the rich threshold structures in the collision cross-sections are completely understood.

?ížek, M.; Horá?ek, J.; Allan, M.; Domcke, W.

2002-09-01

200

Acetate Threshold Concentrations Suggest Varying Energy Requirements during Anaerobic Respiration by Anaeromyxobacter dehalogenans  

Microsoft Academic Search

Acetate threshold concentrations were determined under chlororespiring and Fe(III)-reducing conditions for Anaeromyxobacter dehalogenans strain 2CP-C. The acetate threshold concentrations measured were 69 4, 19 8, and <1 nM for chlororespiration, amorphous Fe(III) reduction, and Fe(III) citrate reduction, respectively. Residual G values of 75.4 kJ\\/mol of electrons for chlororespiration and 41.5 kJ\\/mol of electrons for amorphous Fe(III) reduction were calculated at

Qiang He; Robert A. Sanford

2004-01-01

201

Energy sorghum biomass harvest thresholds and tillage effects on soil organic carbon and bulk density  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bioenergy feedstock production systems face many challenges, among which is the lack of guidelines on sustainable biomass harvest thresholds, and tillage cropping systems that minimize the potential cumulative effects of fresh biomass harvesting equipment-induced soil compaction. We used the ALMANAC...

202

Ultra-low-energy electron scattering cross section measurements of Ar, Kr and Xe employing the threshold photoelectron source  

NASA Astrophysics Data System (ADS)

A new experimental technique for the measurements of the total cross section for electron scattering from atoms and molecules at very low energy is described. Momentum transfer cross sections for scattering from Ar, Kr and Xe at very low energies were carefully derived using the modified effective range theory from the recently measured total cross sections, which were obtained with a new experimental technique utilizing the threshold photoelectron source. A significant discrepancy between the momentum cross sections derived from the present analysis and those determined in the previous electron swarm studies was found at energies below 100 meV. The findings emphasize the need of further high precision experiments in the very low energy region as well as re-analysis of the previous swarm data.

Kitajima, M.; Kurokawa, M.; Kishino, T.; Toyoshima, K.; Odagiri, T.; Kato, H.; Anzai, K.; Hoshino, M.; Tanaka, H.; Ito, K.

2012-05-01

203

Potential energy threshold for nano-hillock formation by impact of slow highly charged ions on a CaF 2(1 1 1) surface  

Microsoft Academic Search

We investigate the formation of nano-sized hillocks on the (111) surface of CaF2 single crystals by impact of slow highly charged ions. Atomic force microscopy reveals a surprisingly sharp and well-defined threshold of potential energy carried into the collision of about 14keV for hillock formation. Estimates of the energy density deposited suggest that the threshold is linked to a solid–liquid

A. S. El-Said; W. Meissl; M. C. Simon; J. R. Crespo López-Urrutia; C. Lemell; J. Burgdörfer; I. C. Gebeshuber; Hp. Winter; J. Ullrich; C. Trautmann; M. Toulemonde; F. Aumayr

2007-01-01

204

s-wave threshold in electron attachment - Observations and cross sections in CCl4 and SF6 at ultralow electron energies  

Microsoft Academic Search

The threshold photoionization method was used to study low-energy electron attachment phenomena in and cross sections of CCl4 and SF6 compounds, which have applications in the design of gaseous dielectrics and diffuse discharge opening switches. Measurements were made at electron energies from below threshold to 140 meV at resolutions of 6 and 8 meV. A narrow resolution-limited structure was observed

A. Chutjian; S. H. Alajajian

1985-01-01

205

Spatial Variable Thresholding for SCALES  

Microsoft Academic Search

The Stochastic Coherent Adaptive Large Eddy Simulation (SCALES) is a novel wavelet-based approach that resolves energy containing turbulent motions using wavelet multiresolution decomposition and self-adaptivity. The extraction of the most energetic structures is achieved using wavelet thresholding filter with a priori prescribed threshold level. This strategy, although successful, has a major drawback: the thresholding criterion is global and does not

Alireza Nejadmalayeri; Oleg V. Vasilyev; Alexei Vezolainen; Giuliano de Stefano

2009-01-01

206

Detection of ultrahigh-energy cosmic rays and neutrinos by a lunar nanosatellite-borne radio receiver  

Microsoft Academic Search

The feasibility of ultrahigh-energy cosmic ray and neutrino detection by a lunar nanosatellite-borne radio receiver is discussed. The estimated values of the energy threshold and event rate for cosmic ray detection are found to be Eth(CR) ≈ 1018 eV, N(CR, E >= 1019 eV) ≈ a few hundreds of events per day, and N(CR, E >= 1020 eV) is more

V. A. Chechin; B. N. Lomonosov; K. M. Pichkhadze; N. G. Poluhina; V. A. Ryabov; V. K. Sysoev; V. A. Tsarev

2004-01-01

207

Inhibition of the human eyeblink reflex: An evaluation of the sensitivity of the Wendt-Yerkes method of threshold detection  

Microsoft Academic Search

In 2 experiments, 14 college students showed a reduced eyewink reflex to an airpuff (S-sub-2) if it was preceded by a light flash or a noise burst (S-sub-1). Exp I showed that a light inhibited the blink maximally at a 100-msec lag. In Exp III, thresholds for noise pips were established with the method of limits. The pips were then

Levi A. Reiter; James R. Ison

1977-01-01

208

Essays on price dynamics, discovery, and dynamic threshold effects among energy spot markets in North America  

NASA Astrophysics Data System (ADS)

Given the role electricity and natural gas sectors play in the North American economy, an understanding of how markets for these commodities interact is important. This dissertation independently characterizes the price dynamics of major electricity and natural gas spot markets in North America by combining directed acyclic graphs with time series analyses. Furthermore, the dissertation explores a generalization of price difference bands associated with the law of one price. Interdependencies among 11 major electricity spot markets are examined in Chapter II using a vector autoregression model. Results suggest that the relationships between the markets vary by time. Western markets are separated from the eastern markets and the Electricity Reliability Council of Texas. At longer time horizons these separations disappear. Palo Verde is the important spot market in the west for price discovery. Southwest Power Pool is the dominant market in Eastern Interconnected System for price discovery. Interdependencies among eight major natural gas spot markets are investigated using a vector error correction model and the Greedy Equivalence Search Algorithm in Chapter III. Findings suggest that the eight price series are tied together through six long-run cointegration relationships, supporting the argument that the natural gas market has developed into a single integrated market in North America since deregulation. Results indicate that price discovery tends to occur in the excess consuming regions and move to the excess producing regions. Across North America, the U.S. Midwest region, represented by the Chicago spot market, is the most important for price discovery. The Ellisburg-Leidy Hub in Pennsylvania and Malin Hub in Oregon are important for eastern and western markets. In Chapter IV, a threshold vector error correction model is applied to the natural gas markets to examine nonlinearities in adjustments to the law of one price. Results show that there are nonlinear adjustments to the law of one price in seven pair-wise markets. Four alternative cases for the law of one price are presented as a theoretical background. A methodology is developed for finding a threshold cointegration model that accounts for seasonality in the threshold levels. Results indicate that dynamic threshold effects vary depending on geographical location and whether the markets are excess producing or excess consuming markets.

Park, Haesun

209

Teager energy operator for multi-modulation extraction and its application for gearbox fault detection  

NASA Astrophysics Data System (ADS)

This paper presents a parameter-free and broadband approach to detecting gear faults based on vibration signals. The technique is implemented using the Teager energy operator (TEO). It is shown that this operator can extract amplitude, phase and frequency modulations that are associated with various gear faults. Spectral analysis of the TEO-transformed signal provides the necessary information for fault detection. To improve the effectiveness of the proposed technique, we also devised a wavelet de-noising step based on online threshold estimation. In the de-noising step, the threshold estimation is performed through a frequency domain median absolute deviation (FMAD) scheme. The proposed fault detection technique is tested on simulated as well as experimental data acquired from a single-stage bevel gearbox and a two-stage parallel gearbox. US patent pending (serial number: 12/631,528).

Soltani Bozchalooi, I.; Liang, Ming

2010-07-01

210

Energy model for contrast detection: spatial-frequency and orientation selectivity in grating summation  

Microsoft Academic Search

Models of spatial vision usually assume a 'front-end' of spatial-frequency and orientation selective channels. Subthreshold-sum- mation studies have provided some of the strongest support for this notion. We applied a single-channel energy model and a multiple-channels probability-summation model to explore subthreshold-summation phenomena. We measured the contrast thresholds for detection of two superimposed Gabor patches as a function of the spatial-frequency

Velitchko Manahilov; William A. Simpson

2001-01-01

211

Sensitivity and specificity of the 76suprathreshold visual field test to detect eyes with visual field defect by Humphrey threshold testing in a population-based setting: the Thessaloniki eye study  

Microsoft Academic Search

PurposeTo evaluate the screening performance of the 76-Suprathreshold (76-STHR) visual field test to detect eyes with visual field defect (VFD) as measured by Humphrey threshold testing in a population-based setting.

Fotis Topouzis; Anne L. Coleman; Fei Yu; Leonidas Mavroudis; Eleftherios Anastasopoulos; Archimidis Koskosas; Theofanis Pappas; Stavros Dimitrakos; M. Roy Wilson

2004-01-01

212

Energy detection of unknown deterministic signals  

Microsoft Academic Search

By using Shannon's sampling formula, the problem of the detection of a deterministic signal in white Gaussian noise, by means of an energy-measuring device, reduces to the consideration of the sum of the squares of statistically independent Gaussian variates. When the signal is absent, the decision statistic has a central chi-square distribution with the number of degrees of freedom equal

H. Urkowitz

1967-01-01

213

Breakup threshold anomaly for the {sup 8}B + {sup 58}Ni system at near-Coulomb barrier energies  

SciTech Connect

By using recent fusion cross section measurements for the system {sup 8}B + {sup 58}Ni, a simultaneous analysis of elastic scattering, fusion, and total reaction cross sections is performed for the weakly bound system {sup 8}B + {sup 58}Ni at energies close to the Coulomb barrier. The analysis is carried out with an optical potential with fusion and direct reaction parts (i.e., the nuclear polarization potential U is split into a volume part U{sub F}, which accounts for fusion reactions and a surface part U{sub DR}, responsible for direct reactions). The parameters of the Woods-Saxon potentials are determined by a {chi}{sup 2} analysis of the data. The presence of the threshold anomaly is investigated from the energy dependence of both the fusion and direct reaction parts of the polarization potential.

Gomez Camacho, A.; Aguilera, E. F.; Gomes, P. R. S.; Lubian, J. [Departamento de Aceleradores Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, C.P. 11801, Mexico, DF (Mexico); Instituto de Fisica, Universidade Federal Fluminense, Avenida Litoranea s/n, Gragoata Niteroi Rio de Janeiro 24210-340 (Brazil)

2011-09-15

214

Scaling of the Low-Energy Structure in Above-Threshold Ionization in the Tunneling Regime: Theory and Experiment  

NASA Astrophysics Data System (ADS)

A calculation of the second-order (rescattering) term in the S-matrix expansion of above-threshold ionization is presented for the case when the binding potential is the unscreened Coulomb potential. Technical problems related to the divergence of the Coulomb scattering amplitude are avoided in the theory by considering the depletion of the atomic ground state due to the applied laser field, which is well defined and does not require the introduction of a screening constant. We focus on the low-energy structure, which was observed in recent experiments with a midinfrared wavelength laser field. Both the spectra and, in particular, the observed scaling versus the Keldysh parameter and the ponderomotive energy are reproduced. The theory provides evidence that the origin of the structure lies in the long-range Coulomb interaction.

Guo, L.; Han, S. S.; Liu, X.; Cheng, Y.; Xu, Z. Z.; Fan, J.; Chen, J.; Chen, S. G.; Becker, W.; Blaga, C. I.; DiChiara, A. D.; Sistrunk, E.; Agostini, P.; DiMauro, L. F.

2013-01-01

215

[Empirical mode of combination of the wavelet threshold filtering and empirical mode decomposition (EMD) based on energy estimate].  

PubMed

According to the frequency overlapping of intrinsic mode function (IMF) based on the temporal and spatial filtering of empirical mode decomposition (EMD), which will lead to the question of useful signals and noises filtered together, we proposed a method that numbers of IMF is determined by energy estimate, temporal and spatial filtering combing wavelet threshold and EMD integrating wavelet local signal characteristics of time and scale domain. This method not only used multi-resolution wavelet transform features, but also combined the EMD and Hilbert decomposition of the adaptive spectral analysis of instantaneous frequency and significance of the relationship between energy, so as to solve the problem of useful signal being weakened. With MIT/BIH ECG database standard data subjects, experimental results showed it was an effective method of data processing for handling this type of physiological signals under strong noise. PMID:22295693

Li, Xin; Wang, Huihui; Wang, Yueru; Zhao, Fangfang

2011-12-01

216

Tethered balloons for radio detection of ultra high energy cosmic neutrinos in Antarctica  

NASA Astrophysics Data System (ADS)

We present a brief overview of experimental efforts in Antarctica to search for radio pulses from electron-hadron cascades produced by cosmic ultrahigh-energy neutrinos in Antarctic ice. Thus far, the essential features (energy thresholds, effective recording volumes, etc.) of Antarctic neutrino radio experiments can be classified according to the deployment scheme employed: either (1) on the surface of the glacier—RAMAND-type, (2) in holes in the ice at depths of several hundred meters—RICE-type or (3) on board of a stratospheric balloon at an altitude of 40 km—ANITA-type. We herein propose an alternative possibility, namely to use tethered balloons for placing the radio antennas at modest (compared to ANITA) altitudes above the ice surface (1-2 km). This configuration of antennas will reduce (as compared to ANITA) the energy threshold for detection of neutrinos and increase the observation time.

Besson, D.; Dagkesamanskii, R.; Kravchenko, E.; Kravchenko, I.; Zheleznykh, I.

2012-01-01

217

Energy thresholds for air-breakdown plasma formation on the surfaces of solid targets under the action of TEA CO/sub 2/ laser pulses  

SciTech Connect

The first measurements were made of the energy threshold for air breakdown on metallic and dielectric targets when a plasma was formed in the tail of a TEA CO/sub 2/ laser pulse. A study was made of the dependences of the threshold characteristics on the dimensions of the illuminated spot and on the angle of incidence of the radiation on the target. A qualitative interpretation of the results is given.

Ageev, V.P.; Burdin, S.G.; Goncharov, I.N.; Goncharov, Y.N.; Konov, V.I.; Skvortsov, Y.A.; Tokarev, V.N.; Chapliev, N.I.

1983-04-01

218

BRIEF COMMUNICATIONS: Influence of the polarization of radiation on the energy characteristics and threshold of stimulated Raman scattering due to rotational transitions  

NASA Astrophysics Data System (ADS)

It is shown experimentally and theoretically that the threshold intensity for stimulated Raman scattering (STRS) due to rotational transitions depends strongly on the polarization of the pump radiation. The threshold for rotational STRS is lowest for circularly polarized radiation and increases sharply for linearly polarized radiation. The results of investigations of the energy characteristics of rotational STRS on the degree of ellipticity of the pump radiation are presented.

Venkin, G. V.; Il'inski?, Yu A.; Mikheev, G. M.

1985-03-01

219

Leakage-Aware Energy Efficient Scheduling for Fixed-Priority Tasks with Preemption Thresholds  

Microsoft Academic Search

Dynamic Voltage Scaling (DVS), which adjusts the clock speed and supply voltage dynamically, is an effective technique in\\u000a reducing the energy consumption of embedded real-time systems. However, most existing DVS algorithms focus on reducing the\\u000a energy consumption of CPU only, ignoring their negative impacts on task scheduling and system wide energy consumption. In\\u000a this paper, we address one of such

Xiaochuan He; Yan Jia

2008-01-01

220

Development and Utility of an Internal Threshold Control (ITC) Real-Time PCR Assay for Exogenous DNA Detection  

Microsoft Academic Search

Sensitive and specific tests for detecting exogenous DNA molecules are useful for infectious disease diagnosis, gene therapy clinical trial safety, and gene doping surveillance. Taqman real-time PCR using specific sequence probes provides an effective approach to accurately and quantitatively detect exogenous DNA. However, one of the major challenges in these analyses is to eliminate false positive signals caused by either

Weiyi Ni; Caroline Le Guiner; Philippe Moullier; Richard O. Snyder

2012-01-01

221

Collisional energy deposition threshold for extended damage depths in ion-implanted silicates.  

National Technical Information Service (NTIS)

Many properties of implanted fused silica (e.g., surface stress, hardness) exhibit maximum implantation-induced changes for collisional energy deposition values of (approximately)10(sup 20) keV/cm(sup 3). We have observed a second critical energy depositi...

G. W. Arnold G. Battaglin A. Boscolo-Boscoletto F. Caccavalle G. De Marchi

1991-01-01

222

Electron-impact excitation of hydrogen atoms: Energies between the n = 3 and n = 4 thresholds  

SciTech Connect

The cross sections for excitation of hydrogen atoms from the n = 1 and n = 2 states are calculated for incident energies between 12.1 and 12.75 eV. The calculations are made variationally, and employ a large pseudostate basis. Energies and widths of resonances are obtained.

Callaway, J.

1988-05-15

223

Energy Dependent Partial Wave Analysis of (pi+)p yields (Kappa+)(Sigma+) between Threshold and 2.35GeV.  

National Technical Information Service (NTIS)

An energy dependent partial wave analysis of the reaction given in the title has been carried out between threshold and 2.35GeV centre of mass energy using recently published, high statistical precision, data. A single solution giving a satisfactory fit t...

D. J. Candlin D. C. Lowe K. J. Peach L. R. Scotland

1983-01-01

224

The 8Li(p,?)5He reaction at low energies, and 9Be spectroscopy around the proton threshold  

NASA Astrophysics Data System (ADS)

We present a direct measurement of the low-energy 8Li(p,?)5He cross section, using a radioactive 8Li beam impinging on a thick target. With four beam energies, we cover the energy range between Ec.m.=0.2 and 2.1 MeV. An R-matrix analysis of the data is performed and suggests the existence of two broad overlapping resonances (5/2+ at Ec.m.=1.69 MeV and 7/2+ at Ec.m.=1.76 MeV). At low energies our data are sensitive to the properties of a subthreshold state (Ex=16.67 MeV) and of two resonances above threshold. These resonances were observed in previous experiments. The R-matrix fit confirms spin assignments, and provides partial widths. We propose a new 8Li(p,?)5He reaction rate and briefly discuss its influence in nuclear astrophysics.

Mendes, D. R., Jr.; Lépine-Szily, A.; Descouvemont, P.; Lichtenthäler, R.; Guimarães, V.; de Faria, P. N.; Barioni, A.; Pires, K. C. C.; Morcelle, V.; Pampa Condori, R.; Morais, M. C.; Leistenschneider, E.; Lima, C. E. F.; Zamora, J. C.; Alcantara, J. A.; Zagatto, V.; Assunção, M.; Shorto, J. M. B.

2012-12-01

225

Doppler tuning vuv spectroscopy of D{sup -} over an extended photon-energy range around the n=2 threshold  

SciTech Connect

The giant (or shape) resonance in the photodetachment cross section of D{sup -} above the n=2 threshold has been subjected to high-resolution vacuum ultraviolet spectroscopy performed by Doppler tuning of ions stored in the ASTRID storage ring. In order to prevent changes in the overlap between laser and ion beams over the large kinetic-energy range employed in the experiment, a new ion-beam-positioning method based on a quadrupole-shunt technique was applied. The study presents an accurate measurement of parameters for the resonance, which is also denoted {sub 2}(0){sub 2}{sup +} {sup 1}P{sup o}. The resonance has a width of 26(2) meV while the asymmetry parameter q of the Fano profile is 3.2(0.4), which is at variance with the most recent theoretical calculations.

Balling, P.; Raarup, M. K.; Elstroem, U. V.; Martinussen, R.; Petrunin, V. V.; Andersen, T. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

2007-10-15

226

Effects of a Shock Acceleration Injection Threshold On The Post-Shock Electron Energy Spectra  

NASA Astrophysics Data System (ADS)

The ability to accurately predict the absolute intensity of shock accelerated particles requires a quantitative model of the shock acceleration injection process. While a shock wave heats the plasma it passes through and routinely accelerates a small fraction of ambient particles; the average particle that interacts with a non-parallel, fast-mode shock loses kinetic energy. This particle energy loss is required to balances the increase in the Poynting flux across the shock. That is, in the rest frame of non-parallel, magnetosonic, fast-mode shock conservation of energy and Poynting’s theorem leads to: 1) the average charged particle interacting with the shock losing kinetic energy; and 2) that this energy loss coming from contributing to shock front current sheet and being displaced in the rest frame V x B electric field. In the case of nearly perpendicular shocks, in order for electrons to gain energy in the V x B electric field, their grad B drift speed must by greater than their current sheet drift speed, which is in the opposite direction. The electron current sheet drift is an En x B drift, where En is the charge-separation electric field in the shock front which points upstream. Using these criteria, we show that electron shock acceleration injection should only occur when an electron’s pre-shock perpendicular energy is greater than the electrostatic potential drop across the shock divided by (the shock strength minus one). We use this injection criterion with diffusive shock acceleration theory to calculate the post shock, absolute electron spectra for a range of shock Mach numbers and ambient electron populations.

Pesses, M. E.; Brecht, S. H.

2009-12-01

227

Spatial Discrimination Threshold Abnormalities are not Detected in a Pilot Study of DYT6 Dystonia Mutation Carriers  

PubMed Central

Background Spatial discrimination thresholds (SDTs) assess somatosensory integration, and provide a window into better understanding the pathophysiology of dystonia. They are abnormal in some focal dystonias, but normal in DYT1 dystonia. It is unknown whether SDTs are altered in DYT6 gene mutation carriers (C). Methods SDTs were assessed in 17 DYT6 C (including eight manifesting carriers), 15 DYT1 C (including seven manifesting carriers) and 34 controls, using a standardized grating orientation task. Subjects were asked to recognize the orientation of Johnson–Van Boven–Philips (JVP) dome gratings on either index fingertip until 40% or more answers were incorrect. SDTs between indexes were calculated and averaged, with a final SDT assigned to each subject, and tertiles for control SDTs were constructed. Results SDTs of DYT6 C or DYT1 C were comparable to those of controls, and not more likely to be in the worst tertile (p?=?0.8 for DYT6 C vs. controls and p?=?1.0 for DYT1 C vs. controls). This was independent of gene expression. Discussion DYT6 carriers do not have impaired SDTs with the JVP dome paradigm. The normal SDT pattern thus suggests shared sensory physiologic patterns with DYT1 dystonia.

Deik, Andres F.; O'Riordan, Sean; Luciano, Marta San; Shanker, Vicki L.; Raymond, Deborah; Bressman, Susan B.; Saunders-Pullman, Rachel

2012-01-01

228

Adaptive threshold estimation via extreme value theory  

Microsoft Academic Search

Determining a detection threshold to automatically maintain a low false alarm rate is a challenging problem. In a number of different applications, the underlying parametric assumptions of most automatic target detection algorithms are invalid. Therefore, thresholds derived using these incorrect distribution assumptions do not produce desirable results when applied to real sensor data. Monte Carlo methods for threshold determination work

Joshua B. Broadwater; Rama Chellappa

2010-01-01

229

Threshold for detection of diabetic peripheral sensory neuropathy using a range of research grade monofilaments in persons with Type 2 diabetes mellitus  

PubMed Central

Aims To identify the threshold of reduced sensory perception in Type 2 diabetes mellitus (Type 2 DM) using a range of research grade monofilaments. Methods Three groups of participants were recruited into a between subject, cross-sectional study. Group 1(NEW), persons with Type 2 DM diagnosed for less than 2 years (n = 80); Group 2 (EST) persons with Type 2 DM diagnosed for more than 2 years (n = 91), and Group 3, a Comparison group without Type 2 DM (n = 73), resulted in a total study population, n = 244. Research grade monofilaments (2, 4, 6, 8 and 10-gram) were employed using standardised protocol, at 6 sites on the plantar aspect of both feet. The demographic and anthropometric measures of gender, age, height, weight, body mass index (BMI), blood pressure and duration of Type 2 DM since diagnosis (if applicable) of the participants were analysed. Results Perception of the research grade monofilaments differed significantly between the 3 groups (p < 0.05). The 6-gram monofilament was found to be the threshold of normal perception, based on 90% of the Comparison group perceiving the 6-gram monofilament at all sites in contrast to 64% of NEW and 48% of EST groups. Conclusion The 6-gram monofilament was identified as the threshold of normal sensory perception. Inability to perceive the 6-gram monofilament indicates, when using the method described in this study, that diminution of sensory perception is evident. Employing a range of monofilaments, 6, 8 and 10-grams in Type 2 DM foot screening would allow the clinical detection of deteriorating sensory perception and enable implementation of foot protection strategies at an earlier stage than is currently practised.

Thomson, Mary P; Potter, Julia; Finch, Paul M; Paisey, Richard B

2008-01-01

230

Thermal detection thresholds of A?- and C-fibre afferents activated by brief CO2 laser pulses applied onto the human hairy skin.  

PubMed

Brief high-power laser pulses applied onto the hairy skin of the distal end of a limb generate a double sensation related to the activation of A?- and C-fibres, referred to as first and second pain. However, neurophysiological and behavioural responses related to the activation of C-fibres can be studied reliably only if the concomitant activation of A?-fibres is avoided. Here, using a novel CO(2) laser stimulator able to deliver constant-temperature heat pulses through a feedback regulation of laser power by an online measurement of skin temperature at target site, combined with an adaptive staircase algorithm using reaction-time to distinguish between responses triggered by A?- and C-fibre input, we show that it is possible to estimate robustly and independently the thermal detection thresholds of A?-fibres (46.9±1.7°C) and C-fibres (39.8±1.7°C). Furthermore, we show that both thresholds are dependent on the skin temperature preceding and/or surrounding the test stimulus, indicating that the A?- and C-fibre afferents triggering the behavioural responses to brief laser pulses behave, at least partially, as detectors of a change in skin temperature rather than as pure level detectors. Most importantly, our results show that the difference in threshold between A?- and C-fibre afferents activated by brief laser pulses can be exploited to activate C-fibres selectively and reliably, provided that the rise in skin temperature generated by the laser stimulator is well-controlled. Our approach could constitute a tool to explore, in humans, the physiological and pathophysiological mechanisms involved in processing C- and A?-fibre input, respectively. PMID:22558230

Churyukanov, Maxim; Plaghki, Léon; Legrain, Valéry; Mouraux, André

2012-04-25

231

The Nature of Psychological Thresholds  

ERIC Educational Resources Information Center

|Following G. T. Fechner (1966), thresholds have been conceptualized as the amount of intensity needed to transition between mental states, such as between a states of unconsciousness and consciousness. With the advent of the theory of signal detection, however, discrete-state theory and the corresponding notion of threshold have been discounted.…

Rouder, Jeffrey N.; Morey, Richard D.

2009-01-01

232

Difluorocarbene studied with threshold photoelectron spectroscopy (TPES): measurement of the first adiabatic ionization energy (AIE) of CF(2).  

PubMed

The first photoelectron band of difluorocarbene CF(2), has been studied by threshold photoelectron (TPE) spectroscopy. CF(2) was prepared by microwave discharge of a flowing mixture of hexafluoropropene, C(3)F(6), and argon. A vibrationally resolved band was observed in which at least twenty-two components were observed. In the first PE band of CF(2), the adiabatic ionization energy differs significantly from the vertical ionization energy because, for the ionization CF(2) (+) (X(2)A(1))+e(-) <-- CF(2) (X(1)A(1)), there is an increase in the FCF bond angle (by approximately 20 degrees ) and a decrease in the C--F bond length (by approximately 0.7 A). The adiabatic component was not observed in the experimental TPE spectrum. However, on comparing this spectrum with an ab initio/Franck-Condon simulation of this band, using results from high-level ab initio calculations, the structure associated with the vibrational components could be assigned. This led to alignment of the experimental TPE spectrum and the computed Franck-Condon envelope, and a determination of the first adiabatic ionization energy of CF(2) as (11.362+/-0.005) eV. From the assignment of the vibrational structure, values were obtained for the harmonic and fundamental frequencies of the symmetric stretching mode (nu(1)') and symmetric bending mode (nu(2)') in CF(2) (+) (X(2)A(1)). PMID:19006171

Innocenti, Fabrizio; Eypper, Marie; Lee, Edmond P F; Stranges, Stefano; Mok, Daniel K W; Chau, Foo-tim; King, George C; Dyke, John M

2008-01-01

233

Ovipositional preferences, damage thresholds, and detection of the tomato-potato psyllid Bactericera cockerelli (Homoptera: Psyllidae) on selected tomato accessions.  

PubMed

The tomato-potato psyllid Bactericera [Paratrioza] cockerelli (Sulc) has recently caused losses exceeding 50% on fresh market tomatoes in California and Baja, Mexico by injecting a toxin that results in a condition known as 'psyllid yellows'. The objectives of this study were to: (i) document oviposition preferences on a range of tomato cultivars; (ii) determine threshold levels for psyllid densities that would cause psyllid yellows on tomatoes within the first three weeks following transplanting; and (iii) identify the most important 'psyllid yellows' symptoms that might be used in surveying and monitoring for this pest. Plant lines tested included the commonly-planted commercial cultivars 'Shady Lady' and 'QualiT 21', an older, previously commercial cultivar '7718 VFN', a common cultivar planted by consumers 'Yellow Pear', and a wild type plant accession, PI 134417. When given a choice, psyllids significantly preferred 'Yellow Pear' and avoided PI 134417 for oviposition. Under no-choice conditions psyllids laid significantly fewer eggs on PI 134417, but all the other plant lines were equally good substrates for laying eggs. Thus, oviposition preference is not likely to provide a functional management strategy in large plantings. On 'Shady Lady', psyllids preferred to oviposit on plants already infested with adults. On both 'Shady Lady' and '7718 VFN' oviposition was significantly greater on plants previously infested by nymphs as compared to uninfested control plants. This suggests that, at least for some cultivars, there is a physiological change in plant attractiveness following psyllid feeding. 'Yellow Pear' and 'QualiT 21' were relatively tolerant of psyllids, requiring 18 nymphs per plant to produce the disease symptoms. Only eight nymphs per plant were needed on 'Shady Lady' and '7718 VFN'. For all cultivars, the pest density showed strong correlations with measurements such as the number of yellowing leaves and leaflets and distorted leaves, which were as good as or better than the first factor extracted from principal component analysis. Therefore, such measurements have the potential to simplify field surveys. PMID:16556341

Liu, D; Trumble, J T

2006-04-01

234

Segment Optimization and Data-Driven Thresholding for Knowledge-Based Landslide Detection by Object-Based Image Analysis  

Microsoft Academic Search

To detect landslides by object-based image analysis using criteria based on shape, color, texture, and, in particular, contextual information and process knowledge, candidate seg- ments must be delineated properly. This has proved challenging in the past, since segments are mainly created using spectral and size criteria that are not consistent for landslides. This paper presents an approach to select objectively

Tapas Ranjan Martha; Norman Kerle; Cees J. van Westen; Victor Jetten; K. Vinod Kumar

2011-01-01

235

Threshold electron excitation of Na  

SciTech Connect

Electron collisional excitation of the 4{ital D}, 5{ital D}, 4{ital P}, and 6{ital S} states of Na has been measured with about 30-meV energy resolution. Very rapid, unresolved threshold onsets are seen for all but the 4{ital P} state, and a near-threshold resonance is suggested by the 5{ital D} data. However, only weak undulations in the cross sections are observed above threshold.

Marinkovic, B.; Wang, P.; Gallagher, A. (Joint Institute for Laboratory Astrophysics, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440 (United States))

1992-09-01

236

Cognitive load and detection thresholds in car following situations: safety implications for using mobile (cellular) telephones while driving  

Microsoft Academic Search

This study was aimed at investigating drivers’ ability to detect a car ahead decelerating, while doing mobile phone related tasks. Nineteen participants aged between 20 and 29 years, (2000–125?000 km driving experience) drove at 80 km\\/h, 50 m behind a lead car, on a 30 km section of motorway in normal traffic. During each trial the lead car started to

Dave Lamble; Tatu Kauranen; Matti Laakso; Heikki Summala

1999-01-01

237

K-shell ionization of Al induced by ions near the threshold energy  

NASA Astrophysics Data System (ADS)

The K-shell ionization cross sections of Al induced by H+ and Ne7+ were studied. The ionization cross sections obtained are compared with the predictions of ECPSSR theory (based on the perturbed-stationary-state approach including Coulomb deflection, energy loss and relativistic corrections), BEA (binary encounter approximation) and 1s? molecular-orbital ionization. It is found that the ECPSSR theoretical results agree with the experimental data very well for proton impact, while the BEA model with correction of Coulomb deflection shows good agreement with experimental results.

Wang, Xing; Zhao, Yongtao; Cheng, Rui; Zhou, Xianming; Lei, Yu; Sun, Yuanbo; Wang, Yuyu; Ren, Jieru; Yu, Yang; Li, Yongfeng; Xu, Ge; Zhang, Xiaoan; Li, Yaozong; Liang, Changhui; Xiao, Guoqing

2013-09-01

238

Low energy threshold analysis of the phase I and phase II data sets of the Sudbury neutrino observatory  

SciTech Connect

Results are reported from a joint analysis of Phase I and Phase II data from the Sudbury Neutrino Observatory. The effective electron kinetic energy threshold used is T{sub eff} = 3.5 MeV, the lowest analysis threshold yet achieved with water Cherenkov detector data. In units of 10{sup 6} cm{sup -2} s{sup =1}, the total flux of active-flavor neutrinos from {sup 8}B decay in the Sun measured using the neutral current (NC) reaction of neutrinos on deuterons, with no constraint on the {sup 8}B neutrino energy spectrum, is found to be {Phi}{sub NC} = 5.140{sub -0.158}{sup +0.160}(stat){sub -0.117}{sup +0.132}(syst). These uncertainties are more than a factor of two smaller than previously published results. Also presented are the spectra of recoil electrons from the charged current reaction of neutrinos on deuterons and the elastic scattering of electrons. A fit to the SNO data in which the free parameters directly describe the total {sup 8}B neutrino flux and the energy-dependent Ve survival probability provides a measure of the total {sup 8}B neutrino flux {Phi}{sub 8{sub B}} = 5.046{sub -0.152}{sup +0.159}(stat){sub -0.123}{sup +0.107}(syst). Combining these new results with results of all other solar experiments and the KamLAND reactor experiment yields best-fit values of the mixing parameters of {theta}{sub 12} = 34.06{sub -0.84}{sup +1.16} degrees and {Delta}m{sub 21}{sup 2} = 7.59{sub -0.21}{sup +0.20} x 10{sup -5} eV{sup 2}. The global value of {Phi}{sub 8{sub B}} is extracted to a precision of {sub -2.95}{sup +2.38}%. In a three-flavor analysis the best fit value of sin{sup 2} {theta}{sub 13} is 2.00{sub -1.63}{sup +2.09} x 10{sup -2}. Interpreting this as a limit implies an upper bound of sin{sup 2} {theta}{sub 13} < 0.057 (95% C. L.).

Seibert, S R [Los Alamos National Laboratory; Hime, A [Los Alamos National Laboratory; Elliott, S R [Los Alamos National Laboratory; Rielage, K [Los Alamos National Laboratory

2009-01-01

239

Threshold contrast detail detectability measurement of the fluoroscopic image quality of a dynamic solid-state digital x-ray image detector.  

PubMed

Solid-state digital x-ray imaging detectors of flat-panel construction will play an increasingly important role in future medical imaging facilities. Solid-state detectors that will support both dynamic (including fluoroscopic) and radiographic image recording are under active development. The image quality of an experimental solid-state digital x-ray image detector operating in a continuous fluoroscopy mode has been investigated. The threshold contrast detail detectability (TCDD) technique was used to compare the fluoroscopic imaging performance of an experimental dynamic solid-state digital x-ray image detector with that of a reference image intensifier television (IITV) fluoroscopy system. The reference system incorporated Plumbicon TV. Results were presented as a threshold detection index, or H(T)(A), curves. Measurements were made over a range of mean entrance air kerma (EAK) rates typically used in conventional IITV fluoroscopy. At the upper and mid EAK rate range (440 and 220 nGy/s) the solid-state detector outperformed the reference IITV fluoroscopy system as measured by TCDD performance. At the lowest measured EAK rate (104 nGy/s), the solid-state detector produces slightly inferior TCDD performance compared with the reference system. Although not statistically significant at this EAK rate, the difference will increase as EAK is lowered further. Overall the TCDD results and early clinical experiences support the proposition that a current design of dynamic solid-state detector produces image quality competitive with that of modern IITV fluoroscopy systems. These findings encourage the development of compact and versatile universal x-ray imaging systems based upon solid-state detector technology to support R & F and vascular/interventional applications. PMID:11213916

Davies, A G; Cowen, A R; Kengyelics, S M; Bury, R F; Bruijns, T J

2001-01-01

240

Valence double ionization of O2 at photon energies below and above the molecular double ionization threshold.  

PubMed

A recently developed time-of-flight photoelectron-photoelectron coincidence spectroscopy technique, which gives complete two-dimensional e(-)-e(-) spectra in single photon double ionization, is applied to molecular oxygen at photon energies below and above the adiabatic double ionization threshold of O(2). Analysis of the two-dimensional coincidence maps reveals specific indirect pathways for the double ionization process. Dissociative ionization paths with subsequent autoionization of atomic oxygen are found to be the dominant processes for all chosen photon energies. Spectra of the photoelectrons coincident with the autoionization electrons show that intermediate O(2)(+) states are involved which do not autoionize to molecular O(2)(2+). In particular, the ground state of O(2)(2+) is vibrationally resolved and shows a regular progression which can be well described by direct Franck-Condon transitions at an internuclear distance R(e)(X (1)Sigma(g)(+))=1.054 A. Quantum yields of double ionization for O(2), of a form discussed in this paper, are determined. PMID:15847523

Feifel, R; Eland, J H D; Edvardsson, D

2005-04-01

241

Higher quantum bound for the Vértesi-Bene-Bell inequality and the role of positive operator-valued measures regarding its threshold detection efficiency  

NASA Astrophysics Data System (ADS)

Recently, Vértesi and Bene [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.82.062115 82, 062115 (2010)] derived a two-qubit Bell inequality ICH3, which they show to be maximally violated only when more general positive operator-valued measures (POVMs) are used instead of the usual von Neumann measurements. Here we consider a general parametrization for the three-element POVM involved in the Bell test and obtain a higher quantum bound for the ICH3 inequality. With a higher quantum bound for ICH3, we investigate whether there is an experimental setup that can be used for observing that POVMs give higher violations in Bell tests based on this inequality. We analyze the maximum errors supported by the inequality to identify a source of entangled photons that can be used for the test. Then we study whether POVMs are also relevant in the more realistic case where partially entangled states are used in the experiment. Finally, we investigate the required efficiencies of the ICH3 inequality, and the type of measurements involved, for closing the detection loophole. We obtain the result that POVMs allow for the lowest threshold detection efficiency, and that it is comparable to the minimal required detection efficiency (in the case of two qubits) of the Clauser-Horne-Bell inequality.

Barra, J. F.; Gómez, E. S.; Cañas, G.; Nogueira, W. A. T.; Neves, L.; Lima, G.

2012-10-01

242

Near-threshold sputtering of MoSi2  

NASA Astrophysics Data System (ADS)

This paper presents a comprehensive experimental, theoretical and computer simulation study of very low-energy (3-35eV) argon ion sputtering of ?-MoSi2 (0001). Modification of MoSi2 surface composition under low-energy ion bombardment was studied by Auger electron spectroscopy (AES) and X-ray photoelectronic spectroscopy (XPS). The detected changes of surface composition were attributed to preferential sputtering combined with threshold effects. To verify the interpretation, an analytical theory of near-threshold sputtering of compounds is developed which provides a general relation between the sputter threshold energy of target atoms on one side and their atomic masses, surface-binding energies as well with the ion atomic mass on the other side. Elementary mechanisms of near-threshold sputtering are found from the theory and molecular dynamics simulation for MoSi2. Threshold energies for various mechanisms of Mo and Si sputtering are calculated and used to explain the experimental evidence. From results of the work it is concluded that the experimental study of surface composition changes after near-threshold sputtering provides a radically new approach to investigate surface binding in compounds.

Soshnikov, I. P.; Stepanova, M. G.; Matin, E. N.; Shakhmin, A. L.; Khodorkovsky, M. A.; Bert, N. A.

243

Mitochondrial threshold effects.  

PubMed Central

The study of mitochondrial diseases has revealed dramatic variability in the phenotypic presentation of mitochondrial genetic defects. To attempt to understand this variability, different authors have studied energy metabolism in transmitochondrial cell lines carrying different proportions of various pathogenic mutations in their mitochondrial DNA. The same kinds of experiments have been performed on isolated mitochondria and on tissue biopsies taken from patients with mitochondrial diseases. The results have shown that, in most cases, phenotypic manifestation of the genetic defect occurs only when a threshold level is exceeded, and this phenomenon has been named the 'phenotypic threshold effect'. Subsequently, several authors showed that it was possible to inhibit considerably the activity of a respiratory chain complex, up to a critical value, without affecting the rate of mitochondrial respiration or ATP synthesis. This phenomenon was called the 'biochemical threshold effect'. More recently, quantitative analysis of the effects of various mutations in mitochondrial DNA on the rate of mitochondrial protein synthesis has revealed the existence of a 'translational threshold effect'. In this review these different mitochondrial threshold effects are discussed, along with their molecular bases and the roles that they play in the presentation of mitochondrial diseases.

Rossignol, Rodrigue; Faustin, Benjamin; Rocher, Christophe; Malgat, Monique; Mazat, Jean-Pierre; Letellier, Thierry

2003-01-01

244

The energy ratio mapping algorithm: a tool to improve the energy-based detection of odontocete echolocation clicks.  

PubMed

The energy ratio mapping algorithm (ERMA) was developed to improve the performance of energy-based detection of odontocete echolocation clicks, especially for application in environments with limited computational power and energy such as acoustic gliders. ERMA systematically evaluates many frequency bands for energy ratio-based detection of echolocation clicks produced by a target species in the presence of the species mix in a given geographic area. To evaluate the performance of ERMA, a Teager-Kaiser energy operator was applied to the series of energy ratios as derived by ERMA. A noise-adaptive threshold was then applied to the Teager-Kaiser function to identify clicks in data sets. The method was tested for detecting clicks of Blainville's beaked whales while rejecting echolocation clicks of Risso's dolphins and pilot whales. Results showed that the ERMA-based detector correctly identified 81.6% of the beaked whale clicks in an extended evaluation data set. Average false-positive detection rate was 6.3% (3.4% for Risso's dolphins and 2.9% for pilot whales). PMID:21476637

Klinck, Holger; Mellinger, David K

2011-04-01

245

Signal processing of sensor node data for vehicle detection  

Microsoft Academic Search

We describe an algorithm and experimental work for vehicle detection using sensor node data. Both acoustic and magnetic signals are processed for vehicle detection. We propose a real-time vehicle detection algorithm called the adaptive threshold algorithm (ATA). The algorithm first computes the time-domain energy distribution curve and then slices the energy curve using a threshold updated adaptively by some decision

J. Ding; S.-Y. Cheung; C.-W. Tan; P. Varaiya

2004-01-01

246

{alpha}-cluster states above the threshold energy in {sup 44}Ti  

SciTech Connect

The angular distributions of the cross sections of reactions to levels up to {ital E}{sub {ital X}}=11 MeV in {sup 44}Ti were measured for the reaction {sup 40}Ca({sup 6}Li,{ital d}) at {ital E}=37 MeV. These angular distributions for the unbound states, particularly the well populated 7.67(10{sup +}), 8.04(12{sup +}), 8.54, 8.96, 9.58, and 10.86 MeV states, were analyzed together with the data at {ital E}=50 MeV using {alpha}-particle wave functions calculated at the resonance energies using the squared Woods-Saxon potentials. The strongly excited state at {ital E}{sub {ital X}}=10.86 MeV, whose spin parity was not identified from the data at 50 MeV, was found to be a candidate for the bandhead state of the higher nodal {ital K}{sup {pi}}=0{sup +} band with principal quantum number {ital N}=14. {copyright} {ital 1996 The American Physical Society.}

Yamaya, T.; Ishigaki, K.; Ishiyama, H. [Department of Physics, Tohoku University, Sendai 980 (Japan); Suehiro, T. [Tohoku Institute of Technology, Sendai 982 (Japan); Kato, S. [Department of Physics, Yamagata University, Yamagata 900 (Japan); Fujiwara, M. [Research Center for Nuclear Physics, Osaka University, Osaka 567 (Japan); Katori, K. [Department of Physics, Osaka University, Osaka 588 (Japan); Tanaka, M.H.; Kubono, S.; Guimaraes, V. [Institute for Nuclear Study, University of Tokyo, Tanashi, Tokyo 188 (Japan); Ohkubo, S. [Department of Applied Science, Kochi Womens University, Kochi 780 (Japan)

1996-01-01

247

Photodissociation spectroscopy of stored CH+ ions: Detection, assignment, and close-coupled modeling of near-threshold Feshbach resonances  

NASA Astrophysics Data System (ADS)

We have measured and theoretically analyzed a photodissociation spectrum of the CH+ molecular ion in which most observed energy levels lie within the fine-structure splitting of the C+ fragment and predissociate, and where the observed irregular line shapes and dipole-forbidden transitions indicate that nonadiabatic interactions lead to multichannel dynamics. The molecules were prepared in low rotational levels J''=0-9 of the vibrational ground state X 1Sigma+ (v'')=0 by storing a CH+ beam at 7.1 MeV in the heavy-ion storage ring TSR for up to 30 s, which was sufficient for the ions to rovibrationally thermalize to room temperature by spontaneous infrared emission. The internally cold molecules were irradiated with a dye laser at photon energies between 31 600-33 400 cm-1, and the resulting C+ fragments were counted with a particle detector. The photodissociation cross section displays the numerous Feshbach resonances between the two C+ fine-structure states predicted by theory for low rotation. The data are analyzed in two steps. First, from the overall structure of the spectrum, by identifying branches, and by a Le Roy-Bernstein analysis of level spacings we determine the dissociation energy D0=(32 946.7plus-or-minus1.1) cm-1 (with respect to the lower fine-structure limit) and assign the strongest features to the vibrational levels v'=11-14 of the dipole-allowed A 1Pi state. The majority of the 66 observed resonances cannot be assigned in this way. Therefore, in a second step, the complete spectrum is simulated with a close-coupling model, starting from recent ab initio Born-Oppenheimer potentials. For the long-range induction, dispersion and exchange energies, we propose an analytical expression and derive the C6 coefficients. After a systematic variation of just the vibrational defects of the four Born-Oppenheimer potentials involved, the close-coupling model yields a quantitative fit to the measured cross section in all detail, and is used to assign most of the remaining features to the dipole-forbidden a 3Pi state (v')=17-20, and some to the weakly bound c 3Sigma+ state (v')=0-2. The model potentials, which reproduce the spectrum and compactly represent the spectroscopic data, should help to predict more accurately C++H scattering in the interstellar medium.

Hechtfischer, Ulrich; Williams, Carl J.; Lange, Michael; Linkemann, Joachim; Schwalm, Dirk; Wester, Roland; Wolf, Andreas; Zajfman, Daniel

2002-11-01

248

Potential energy threshold for nano-hillock formation by impact of slow highly charged ions on a CaF2(1 1 1) surface  

NASA Astrophysics Data System (ADS)

We investigate the formation of nano-sized hillocks on the (1 1 1) surface of CaF2 single crystals by impact of slow highly charged ions. Atomic force microscopy reveals a surprisingly sharp and well-defined threshold of potential energy carried into the collision of about 14 keV for hillock formation. Estimates of the energy density deposited suggest that the threshold is linked to a solid liquid phase transition (“melting”) on the nanoscale. With increasing potential energy, both the basal diameter and the height of the hillocks increase. The present results reveal a remarkable similarity between the present predominantly potential energy driven process and track formation by the thermal spike of swift (˜GeV) heavy ions.

El-Said, A. S.; Meissl, W.; Simon, M. C.; Crespo López-Urrutia, J. R.; Lemell, C.; Burgdörfer, J.; Gebeshuber, I. C.; Winter, Hp.; Ullrich, J.; Trautmann, C.; Toulemonde, M.; Aumayr, F.

2007-05-01

249

Mass analyzed threshold ionization spectra of phenol...Ar2: ionization energy and cation intermolecular vibrational frequencies.  

PubMed

The phenol(+)...Ar(2) complex has been characterized in a supersonic jet by mass analyzed threshold ionization (MATI) spectroscopy via different intermediate intermolecular vibrational states of the first electronically excited state (S(1)). From the spectra recorded via the S(1)0(0) origin and the S(1)?(x) intermolecular vibrational state, the ionization energy (IE) has been determined as 68,288 ± 5 cm(-1), displaying a red shift of 340 cm(-1) from the IE of the phenol(+) monomer. Well-resolved, nearly harmonic vibrational progressions with a fundamental frequency of 10 cm(-1) have been observed in the ion ground state (D(0)) and assigned to the symmetric van der Waals (vdW) bending mode, ?(x), along the x axis containing the C-O bond. MATI spectra recorded via the S(1) state involving other higher-lying intermolecular vibrational states (?(s)(1), ?(x)(3), ?(s)(1)?(x)(1), ?(s)(1)?(x)(2)) are characterized by unresolved broad structures. PMID:21063583

Armentano, Antonio; Tong, Xin; Riese, Mikko; Pimblott, Simon M; Müller-Dethlefs, K; Fujii, Masaaki; Dopfer, Otto

2010-11-09

250

Electrophysiological Correlates of the Threshold to Detection of Passive Motion: An Investigation in Professional Volleyball Athletes with and without Atrophy of the Infraspinatus Muscle  

PubMed Central

The goal of the present study is to compare the electrophysiological correlates of the threshold to detection of passive motion (TTDPM) among three groups: healthy individuals (control group), professional volleyball athletes with atrophy of the infraspinatus muscle on the dominant side, and athletes with no shoulder pathologies. More specifically, the study aims at assessing the effects of infraspinatus muscle atrophy on the cortical representation of the TTDPM. A proprioception testing device (PTD) was used to measure the TTDPM. The device passively moved the shoulder and participants were instructed to respond as soon as movement was detected (TTDPM) by pressing a button switch. Response latency was established as the delay between the stimulus (movement) and the response (button press). Electroencephalographic (EEG) and electromyographic (EMG) activities were recorded simultaneously. An analysis of variance (ANOVA) and subsequent post hoc tests indicated a significant difference in latency between the group of athletes without the atrophy when compared both to the group of athletes with the atrophy and to the control group. Furthermore, distinct patterns of cortical activity were observed in the three experimental groups. The results suggest that systematically trained motor abilities, as well as the atrophy of the infraspinatus muscle, change the cortical representation of the different stages of proprioceptive information processing and, ultimately, the cortical representation of the TTDPM.

Salles, Jose Inacio; Cossich, Victor Rodrigues Amaral; Amaral, Marcus Vinicius; Monteiro, Martim T.; Cagy, Mauricio; Motta, Geraldo; Velasques, Bruna; Piedade, Roberto; Ribeiro, Pedro

2013-01-01

251

Radio Detection of Ultra High Energy Neutrinos  

NASA Astrophysics Data System (ADS)

Ultra high energy cosmic rays interact with the cosmic microwave background radiation, resulting in the production of energetic pions. These interactions result in energy loss by the incident cosmic ray leading to the Greisen-Zatsepin-Kuzmin (GZK) feature in the cosmic ray spectrum at about 4×10^19 eV, and the decay of the charged pions produced in these interactions results in neutrinos known as Berezinskii-Zatsepin (BZ) neutrinos. These neutrinos interact only via the weak interaction, with negligible absorption over cosmic distances but interaction lengths in the Earth of a few hundred kilometers. When these neutrinos interact in a dense medium, the electromagnetic component of the resulting shower develops a negative charge excess due to Compton scattering of the electrons from the medium and depletion of positrons by in-flight annihilation. This macroscopic charge excess moves at nearly the speed of light, and its passage through a dielectric medium results in coherent Cherenkov radiation at radio wavelengths longer than the size of the radiating region. This process is known as the Askaryan mechanism, and has been observed in accelerator experiments. The radio pulse is impulsive, and can be detected over large volumes in materials with long radio attenuation lengths, most notably the cold ice in the Antarctic ice sheet. Upper limits on the neutrino flux obtained by the balloon-borne instrument ANITA are now approaching the expected flux, and prototype in-ice antenna arrays are now being deployed. Prospects for large detectors capable of detecting hundreds of these neutrinos will be discussed. This work is supported by NASA under grants NNX08AC17G and NNX11AC45G, by the NSF under grant PHY-0758082, and by the Ohio State Center for Cosmology and Particle Astrophysics (CCAPP).

Beatty, James J.

2011-05-01

252

Computed tomography (CT) bone segmentation of an ancient Egyptian mummy: a comparison of automated and semiautomated threshold and dual-energy techniques.  

PubMed

Dual-energy computed tomography (CT) enables 3-dimensional,noninvasive, and nondestructive imaging with material separation. Dual-energy CT is generally used to segment hydrated tissues within the clinical context. We apply dual-energy CT to an ancient Egyptian mummy and present several techniques designed to separate bone from desiccated tissue and resin. Automated and semiautomated dual-energy CT techniques are compared to manual segmentation and thresholding-based techniques. Semiautomated techniques enable substantial reductions in operator time compared to manual segmentation. PMID:22992615

Friedman, Saul N; Nguyen, Ngan; Nelson, Andrew J; Granton, Patrick V; MacDonald, D Blair; Hibbert, Rebecca; Holdsworth, David W; Cunningham, Ian A

253

The Influence of Olfactory Concept on the Probability of Detecting Sub and Peri-threshold Components in a Mixture of Odorants  

Microsoft Academic Search

The headspace of apple juice was analysed to obtain an ecologically relevant stimulus model mixture of apple volatiles. Two sets of volatiles were made up: a set of eight supra-threshold volatiles (MIX)and a set of three sub-threshold volatiles. These sets were used to test the hypothesis that sub-threshold components can change the quality of a familiar smelling mixture of odorants

Johannes H. F. Bult; Hendrik N. J. Schifferstein; Jacques P. Roozen; Alphons G. J. Voragen

2001-01-01

254

How Real Detector Thresholds Create False Standard Candles  

NASA Astrophysics Data System (ADS)

GRB satellites are relatively inefficient detectors of dim hard bursts. For example, given two bursts of identical peak luminosity near the detection threshold, a dim soft burst will be preferentially detected over a dim hard burst. This means that a high Epeak burst will need a higher peak luminosity to be detected than a low Epeak GRB. This purely detector-created attribute will appear as a correlation between Epeak and luminosity, and should not be interpreted as a real standard candle effect. This result derives from Monte Carlo simulations utilizing a wide range of initial GRB spectra, and retriggering to create a final ``detected'' sample. In sum, Epeak is not a good standard candle, and its appearance as such in seeming correlations such as the Amati and other Liso vs. Epeak relations is likely a ghost of real energy-related detection thresholds.

Shahmoradi, Amir; Nemiroff, Robert

2009-05-01

255

Semi-exclusive structure functions and inclusive form factors for ed ? e ? ? NN in the energy region from threshold up to 500 MeV  

Microsoft Academic Search

The separated structure functions RL, RT, RLT, and RTT governing the semi-exclusive differential cross section for the d(e,e??)NN reaction are evaluated in the energy region from threshold up to 500MeV. We present results for both the neutral and the charged pion production channels in a variety of kinematic settings. For the elementary pion electroproduction operator, the realistic unitary isobar MAID-2003

E. M. Darwish; S. S. Al-Thoyaib

2009-01-01

256

Determination of the threshold-energy surface for copper using in-situ electrical-resistivity measurements in the high-voltage electron microscope  

Microsoft Academic Search

A detailed study of the anisotropy of the threshold energy for Frenkel-pair production in copper was carried out experimentally, using in-situ electrical-resistivity measurements in the high-voltage electron microscope. These electrical-resistivity measurements, which are sensitive to small changes in point-defect concentration, were used to determine the damage or defect production rate. Damage-rate measurements in copper single crystals were carried out for

Wayne E. King; K. L. Merkle; M. Meshii

1981-01-01

257

Conduction Band-Tail Estimated from the Temperature Dependence of X1-X3 Threshold Energy in Heavily-Doped n-GaP  

Microsoft Academic Search

Temperature dependences of the threshold energy, delta, between the X1-band with effective mass m1* and the X3-band with m2*, and the ratio m2*\\/m1* were obtained for the donor(Te)-doped GaP with a concentration of ND{=}1.8˜ 60× 1017 cm-3, from the X1-X3 absorption bands measured at various temperatures T and the theoretical curve fittings. delta increases smoothly with decreasing T for 135

Tamio Endo; Yasushi Okino; Nobuhiko Itoh; Hiroyuki Kudo; Koichi Sugiyama

1988-01-01

258

A comparison of various strategies to equalize the lower energy thresholds of a CdTe Medipix2 hexa detector for X-ray imaging applications  

NASA Astrophysics Data System (ADS)

Technological advances have made possible the development of pixelized photon counting semiconductor detectors, many of which are used in X-ray imaging to resolve the spectral composition of the incident photons. Here, in a so-called Hexa detector, we employ a 3 × 2 array of Medipix2 MXR readout chips, bump bonded to a cadmium telluride sensor of 1 mm thickness with a pixel pitch of 165 ?m. Each pixel in this assembly offers two variable energy thresholds, which enables counting of only those photons within an energy range of interest. As manufacturing tolerances cause deviations in each of the pixel's responses, the two thresholds can be calibrated for every pixel to render their response to radiation more homogeneous. In this work, we compare various methods that we chose to equalize the lower thresholds: a) the noise edge of the detector electronics, the characteristic X-rays from b) silver and c) tantalum foils as well as flat fields obtained at d) 40 and e) 120 kVp. It will be shown that the energy dependence in the resulting adjustment bit maps are only small, whereas the question as to which strategy to choose (peak position vs. image homogeneity) will have a greater influence on the resulting corrections. Additionally, we observed a decrease in the mean adjustment values with increasing distance from the central axis of the Hexa detector under study.

Koenig, T.; Zuber, M.; Zwerger, A.; Schuenke, P.; Nill, S.; Fauler, A.; Fiederle, M.; Oelfke, U.

2011-01-01

259

Ferromagnetic Stoner excitations detected by electron-energy-loss spectroscopy  

NASA Astrophysics Data System (ADS)

Spin-flip Stoner excitations have been detected in Fe80B15Si5 using simple electron-energy-loss spectroscopy via the strong energy dependence of the exchange process involved. The Stoner-excitation contribution, obtained as the difference between energy-loss spectra taken with low-energy and high-energy primary electrons, is in good agreement with the results of spin-polarized electron-energy-loss spectroscopy, and with theoretical predictions.

Modesti, S.; Valle, F. Della; Rosei, R.; Tosatti, E.; Glazer, J.

1985-04-01

260

Threshold Logic Drempellogica.  

National Technical Information Service (NTIS)

The theory is discussed of presently available threshold logic circuits, and an analysis of threshold functions is presented. An operational threshold gate adding circuit in TTL technology is described, and the difficulty of improving logic in complex cir...

C. Vader J. W. M. Wasser

1973-01-01

261

MOS Threshold Logic II.  

National Technical Information Service (NTIS)

The program represents the second phase in the Development of MOS threshold logic. Studies were made previously, indicating the limitations and applications of MOS threshold gates. Now, threshold gates were integrated for use in parallel array multipliers...

D. Hampel K. J. Prost N. Scheinberg

1973-01-01

262

Near-threshold sputtering of MoSi 2  

Microsoft Academic Search

This paper presents a comprehensive experimental, theoretical and computer simulation study of very low-energy (3–35 eV) argon ion sputtering of ?-MoSi2(0001). Modification of MoSi2 surface composition under low-energy ion bombardment was studied by Auger electron spectroscopy (AES) and X-ray photoelectronic spectroscopy (XPS). The detected changes of surface composition were attributed to preferential sputtering combined with threshold effects. To verify the

I. P. Soshnikov; M. G. Stepanova; E. N. Matin; A. L. Shakhmin; M. A. Khodorkovsky; N. A. Bert

1999-01-01

263

Near-threshold sputtering of MoSi2  

Microsoft Academic Search

This paper presents a comprehensive experimental, theoretical and computer simulation study of very low-energy (3-35eV) argon ion sputtering of beta-MoSi2 (0001). Modification of MoSi2 surface composition under low-energy ion bombardment was studied by Auger electron spectroscopy (AES) and X-ray photoelectronic spectroscopy (XPS). The detected changes of surface composition were attributed to preferential sputtering combined with threshold effects. To verify the

I. P. Soshnikov; M. G. Stepanova; E. N. Matin; A. L. Shakhmin; M. A. Khodorkovsky; N. A. Bert

1999-01-01

264

On the Energy Detection of Unknown Signals Over Fading Channels  

Microsoft Academic Search

This letter addresses the problem of energy detection of an unknown signal over a multipath channel. It starts with the no-diversity case, and presents some alternative closed-form expressions for the probability of detection to those recently reported in the literature. Detection capability is boosted by implementing both square-law combining and square-law selection diversity schemes

Fadel F. Digham; Mohamed-slim Alouini; Marvin K. Simon

2007-01-01

265

Optimal thresholding for color images  

NASA Astrophysics Data System (ADS)

Color image thresholding is a special case of color clustering which is commonly used for tasks such as object detection, region segmentation, enhancement, and target tracking. As compared to the three-dimensional (3-D) color clustering, thresholding is computationally more efficient for computer implementation and pipelined hardware realization. Traditionally, this method operates on a particular color component whose distribution possesses more prominent peaks than the other two color histograms. In this operation, it is expected that the histogram peaks represent meaningful object areas. However, the color component thresholding results are less reliable than those of 3-D clustering because the valuable information in the other two color components are ignored in region acceptance process. To improve the performance of thresholding, we describe a method that thresholds an input image three times on three different color components independently. The best thresholds are selected by optimizing the within-group variance or directed divergence measure for red, green, and blue distributions separately. The resultant three binary images are combined by means of a predicate logic function that makes use of a 3-input, 1-output majority logic gate. This enables 1-D thresholding mechanism to incorporate the information on all the color components in region acceptance process.

Celenk, Mehmet; Uijt de Haag, Maarten

1998-04-01

266

Energy thresholds that determine membrane integrity and injury in a renal epithelial cell line (LLC-PK1). Relationships to phospholipid degradation and unesterified fatty acid accumulation.  

PubMed Central

This study related ATP levels with membrane damage, lipid abnormalities, and cell death in energy-depleted LLC-PK1 cells. Oxidative phosphorylation was inhibited by antimycin A, and glycolysis was regulated by graded glucose deprivation to achieve stepwise ATP depletion. Over a range of ATP levels down to approximately equal to 5% of normal, over 5 h, cells were altered only minimally, or injured reversibly. Such cells maintained mitochondrial potential, and retained more K+ than cells without an energy source. Over the same duration, cells without an energy source were lethally injured. Treatment with antimycin induced increments of triglycerides and decreases of phospholipids. With severe ATP depletion (approximately equal to 5-10% of normal after 5 h), decrease of phospholipids was marked. Cells in which ATP was not measurable (or was less than 5% of normal) showed comparable phospholipid declines but, in addition, showed massive and progressive increase of unesterified fatty acids. The results identified a low threshold of ATP, at best 5-10% of normal, which preserved viability in LLC-PK1 cells despite major loss of membrane phospholipids. This threshold also determined the ability of cells to maintain their normally low levels of unesterified fatty acids. Failure of energy-dependent mechanisms that normally metabolize unesterified fatty acids may be a correlate of the extent of energy depletion that determines lethal injury. Images

Venkatachalam, M A; Patel, Y J; Kreisberg, J I; Weinberg, J M

1988-01-01

267

Test of Low-Energy Theorems for 1H(?-->, ?0)1H in the Threshold Region  

NASA Astrophysics Data System (ADS)

The photon asymmetry in the reaction 1H(?-->,?0)1H close to threshold has been measured for the first time with the photon spectrometer TAPS using linearly polarized photons from the tagged-photon facility at the Mainz Microtron MAMI. The total and differential cross sections were also measured simultaneously with the photon asymmetry. This allowed determination of the S-wave and all three P-wave amplitudes. The values obtained at threshold are E0+ = [-1.33+/-0.08(stat)+/-0.03(syst)]×10- 3/m?+, P1 = [9.47+/-0.08(stat)+/-0.29(syst)]×10- 3q/m2?+, P2 = [-9.46+/-0.1(stat)+/-0.29(syst)]×10- 3q/m2?+, and P3 = [11.48+/-0.06(stat)+/-0.35(syst)]×10- 3q/m2?+.

Schmidt, A.; Achenbach, P.; Ahrens, J.; Arends, H. J.; Beck, R.; Bernstein, A. M.; Hejny, V.; Kotulla, M.; Krusche, B.; Kuhr, V.; Leukel, R.; MacGregor, I. J.; McGeorge, J. C.; Metag, V.; Olmos de León, V. M.; Rambo, F.; Siodlaczek, U.; Ströher, H.; Walcher, Th.; Weiß, J.; Wissmann, F.; Wolf, M.

2001-12-01

268

Pulse-energy dynamics of passively mode-locked solid-state lasers above the Q-switching threshold  

Microsoft Academic Search

We have investigated the dynamical behavior of various passively mode-locked solid-state lasers by measuring how a modulation of the pump power affects the output power. We show theoretically and experimentally how the damping of the relaxation oscillations is reduced and finally becomes zero when the pump power is reduced so that the threshold for Q-switched mode locking is approached. For

Adrian Schlatter; S. C. Zeller; R. Grange; R. Paschotta; U. Keller

2004-01-01

269

Frequency dependence of vestibuloocular reflex thresholds  

PubMed Central

How the brain processes signals in the presence of noise impacts much of behavioral neuroscience. Thresholds provide one way to assay noise. While perceptual thresholds have been widely investigated, vestibuloocular reflex (VOR) thresholds have seldom been studied and VOR threshold dynamics have never, to our knowledge, been reported. Therefore, we assessed VOR thresholds as a function of frequency. Specifically, we measured horizontal VOR thresholds evoked by yaw rotation in rhesus monkeys, using standard signal detection approaches like those used in earlier human vestibular perceptual threshold studies. We measured VOR thresholds ranging between 0.21 and 0.76°/s; the VOR thresholds increased slightly with frequency across the measured frequency range (0.2–3 Hz). These results do not mimic the frequency response of human perceptual thresholds that have been shown to increase substantially as frequency decreases below 0.5 Hz. These reported VOR threshold findings could indicate a qualitative difference between vestibular responses of humans and nonhuman primates, but a more likely explanation is an additional dynamic neural mechanism that does not influence the VOR but, rather, influences perceptual thresholds via a decision-making process included in direction recognition tasks.

Haburcakova, Csilla; Lewis, Richard F.

2012-01-01

270

Frequency dependence of vestibuloocular reflex thresholds.  

PubMed

How the brain processes signals in the presence of noise impacts much of behavioral neuroscience. Thresholds provide one way to assay noise. While perceptual thresholds have been widely investigated, vestibuloocular reflex (VOR) thresholds have seldom been studied and VOR threshold dynamics have never, to our knowledge, been reported. Therefore, we assessed VOR thresholds as a function of frequency. Specifically, we measured horizontal VOR thresholds evoked by yaw rotation in rhesus monkeys, using standard signal detection approaches like those used in earlier human vestibular perceptual threshold studies. We measured VOR thresholds ranging between 0.21 and 0.76°/s; the VOR thresholds increased slightly with frequency across the measured frequency range (0.2-3 Hz). These results do not mimic the frequency response of human perceptual thresholds that have been shown to increase substantially as frequency decreases below 0.5 Hz. These reported VOR threshold findings could indicate a qualitative difference between vestibular responses of humans and nonhuman primates, but a more likely explanation is an additional dynamic neural mechanism that does not influence the VOR but, rather, influences perceptual thresholds via a decision-making process included in direction recognition tasks. PMID:22072512

Haburcakova, Csilla; Lewis, Richard F; Merfeld, Daniel M

2011-11-09

271

Very low amplified spontaneous emission threshold from a molecular host-guest energy transfer system and electroluminescence from light-emitting diode structure  

NASA Astrophysics Data System (ADS)

We report on the characteristics of a host-guest lasing system obtained by co-evaporation of an oligo(9,9-diarylfluorene) derivative named T3 with the red-emitter 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran dye (DCM). We demonstrate that the ambipolar semiconductor T3 can be implemented as active matrix in the realization of a host-guest system in which an efficient energy transfer takes place from T3 matrix to the lasing DCM molecules. We performed a spectroscopic study on the system by systematically varying the DCM concentration in the T3 matrix. Measurements of steady-state photoluminescence (PL), PL quantum yield (PLQY) and amplified spontaneous emission (ASE) threshold are used to optimize the acceptor concentration at which the ASE from DCM molecules takes place with the lowest threshold. Organic light-emitting diodes (OLEDs) implementing the DCM:T3 host-guest system as recombination layer are fabricated for verifying the optical properties of the optimised blend in real working devices. Indeed, the very low ASE threshold of T3:DCM makes the investigated blend an appealing system for use as active layer in lasing devices. In particular, the ambipolar charge transport properties of the T3 matrix and its field-effect characteristics make the host-guest system presented here an ideal candidate for the realization of electrically-pumped organic lasers.

Toffanin, Stefano; Capelli, Raffaella; Generali, Gianluca; Hwu, Tsyr-Yuan; Wong, Ken-Tsung; Zamboni, Roberto; Muccini, Michele

2009-09-01

272

Anomaly detection in premise energy consumption data  

Microsoft Academic Search

Demand Response (DR) programs are designed to reduce energy consumption for relatively short time periods (e.g., a few hours per event). It has been widely recognized that DR can help to meet both reliability and market needs. In order for DR programs to achieve their full benefits, however, it is critical for utilities to accurately predict the reduction in energy

Yi Zhang; Weiwei Chen; Jason Black

2011-01-01

273

Can the Existence of Dark Energy be Directly Detected?  

SciTech Connect

The majority of astronomers and physicists accept the reality of dark energy and also believe that it can only be studied indirectly through observation of the motions of stars and galaxies. In this paper I open the experimental question of whether it is possible to directly detect dark energy through the presence of dark energy density. Two thirds of this paper outlines the major aspects of dark energy density as now comprehended by the astronomical and physics community. The final third summarizes various proposals for direct detection of dark energy density or its possible effects. At this time I do not have a fruitful answer to the question: Can the Existence of Dark Energy Be Directly Detected?

Perl, Martin L.; /SLAC /KIPAC, Menlo Park

2011-11-23

274

Visible contrast energy metrics for detection and discrimination  

NASA Astrophysics Data System (ADS)

Contrast energy was proposed by Watson, Barlow, and Robson (Science, 1983) as a useful metric for representing luminance contrast target stimuli because it represents the detectability of the stimulus in photon noise for an ideal observer. We propose here the use of visible contrast energy metrics for detection and discrimination among static luminance patterns. The visibility is approximated with spatial frequency sensitivity weighting and eccentricity sensitivity weighting. The suggested weighting functions revise the Standard Spatial Observer (Watson and Ahumada, J. Vision, 2005) for luminance contrast detection , extend it into the near periphery, and provide compensation for duration. Under the assumption that the detection is limited only by internal noise, both detection and discrimination performance can be predicted by metrics based on the visible energy of the difference images.

Ahumada, Albert J.; Watson, Andrew B.

2013-03-01

275

Detection techniques of ultra high energy cosmic rays  

SciTech Connect

Several detection techniques in current high-energy cosmic rays are examined. The results of some experiments are discussed and a review of the future projects is made, emphasizing their discovery potential in accordance with their aperture.

Salazar, H. [Facultad de Ciencias Fisico-Matemaaticas, Universidad Autonoma de Puebla, Puebla, Pue. (Mexico)

1998-10-05

276

The highest energy emission detected by EGRET from blazars  

Microsoft Academic Search

Published EGRET spectra from blazers extend only to 10 GeV, yet EGRET has detected approximately 2000 ?-rays above 10 GeV of which about half are at high Galactic latitude. We report a search of these high-energy ?-rays for associations with the EGRET and TeV detected blazers. Because the point spread function of EGRET improves with energy, only ?2 ?-rays are

Brenda L. Dingus; David L. Bertsch

2001-01-01

277

The highest energy emission detected by EGRET from blazars  

Microsoft Academic Search

Published EGRET spectra from blazers extend only to 10 GeV, yet EGRET has detected approximately 2000 gamma-rays above 10 GeV of which about half are at high Galactic latitude. We report a search of these high-energy gamma-rays for associations with the EGRET and TeV detected blazers. Because the point spread function of EGRET improves with energy, only ~2 gamma-rays are

Brenda L. Dingus; David L. Bertsch

2001-01-01

278

Classification of Energy Consumption in Buildings With Outlier Detection  

Microsoft Academic Search

In this paper, we propose an intelligent data-analysis method for modeling and prediction of daily electricity consumption in buildings. The objective is to enable a building-management system to be used for forecasting and detection of abnormal energy use. First, an outlier-detection method is proposed to identify abnormally high or low energy use in a building. Then a canonical variate analysis

Xiaoli Li; Chris P. Bowers; Thorsten Schnier

2010-01-01

279

Energy detection of a signal with random amplitude  

Microsoft Academic Search

Urkowitz (1967) has discussed the detection of a deterministic signal of unknown structure in the presence of band-limited Gaussian noise. That analysis is developed to the case of a signal with random (Rayleigh, Rice, Nakagami, and other) amplitude. For such amplitude the distribution of a decision statistic of an energy detector is retrieved and expressions for detection probability are obtained.

V. I. Kostylev

2002-01-01

280

Spatial Variable Thresholding for SCALES  

NASA Astrophysics Data System (ADS)

The Stochastic Coherent Adaptive Large Eddy Simulation (SCALES) is a novel wavelet-based approach that resolves energy containing turbulent motions using wavelet multiresolution decomposition and self-adaptivity. The extraction of the most energetic structures is achieved using wavelet thresholding filter with a priori prescribed threshold level. This strategy, although successful, has a major drawback: the thresholding criterion is global and does not fully utilize the spatial/temporal intermittency of the turbulent flow. In the current numerical effort, for the first time (to the best of our knowledge), the concept of physics-based spatially variable thresholding in the context of wavelet-based numerical techniques for solving PDEs is introduced. The procedure consists of tracking the wavelet thresholding-factor within a Lagrangian frame by exploiting a Lagrangian Path-Line Diffusive Averaging approach that uses linear averaging along characteristics. The results for incompressible flow around NACA 0015 airfoil show a very robust and fast methodology for adjusting the thresholding-factor based on dynamically important flow characteristics, for instance, the magnitude of vorticity or strain rate.

Nejadmalayeri, Alireza; Vasilyev, Oleg V.; Vezolainen, Alexei; de Stefano, Giuliano

2009-11-01

281

Radar Detection of High Energy Cosmic Ray Showers  

NASA Astrophysics Data System (ADS)

The radar detection technique for High Energy Cosmic Ray Shower detection has been investigated in this collaborative work. High Energy Cosmic Ray Showers produce disk-like ionization front which moves with relativistic speed in our atmosphere. We study the reflection of radio waves such as the ones from commercial radio and TV stations from the relativistic moving front. The reflected wave experiences a high blue-shift in frequency due to relativistic Doppler Effect. The feasibility study of detection of showers via this method and the benefits will be presented.

Kryemadhi, Abaz; Bakunov, Michael; Maslov, Alex; Novokovskaya, Alina

2012-03-01

282

Chirp Z transform based spectrum sensing via energy detection  

Microsoft Academic Search

In this study, the performance analysis of Fast Fourier Transform and Chirp Z transform based OFDM systems for cognitive radio networks with energy detector model for the spectrum sensing method is realized. Here, energy detection model for noncooperative spectrum sensing is investigated. On the other hand, the analysis is implemented by segmented Chirp z transform. In this study Chirp z

Mustafa Namdar; Baris Sahin; Haci Ilhan; Lutfiye Durak-Ata

2012-01-01

283

Multisensor event detection under temporal correlations with renewable energy sources  

Microsoft Academic Search

Sensor networks have major applications in environmental monitoring, relief operations, surveillance, health-care and defense. Future sensor networks would comprise of sensing devices with energy harvesting capabilities from renewable energy sources such as solar power. Multiple sensor nodes deployed in the region of interest would collaborate to achieve a global objective, such as detection of application specific events. This paper focuses

Neeraj Jaggi; Koushik Kar

2009-01-01

284

Acoustic resonant sensor for ultra high energy neutrino detection  

Microsoft Academic Search

The characterization of the cosmogenic neutrino flux would give insights into cosmological source evolution, source spectra and composition at injection, through the partial recovery of the degraded information carried by the ultra high energy cosmic rays. A suitable technique for the detection of these ultra high energy neutrinos relies on the observation of the coherent radio Cherenkov signature emitted by

L. Braun; R. Frei; J. P. Hertig; B. Howald; G. Masson; J. R. Moser; P. Oberson; A. Pinard; M. Ribordy

2011-01-01

285

Pain threshold and tolerance in Alzheimer's disease  

Microsoft Academic Search

We tested both pain thresholds and pain tolerance in patients with Alzheimer's disease (AD) by means of phasic and tonic noxious stimuli. In the first case, electrical stimulation was used, whereas in the second case arm ischemia was studied. By comparing AD patients with normal subjects of the same age, we found no differences in stimulus detection and pain thresholds,

Fabrizio Benedetti; Sergio Vighetti; Claudia Ricco; Elisabetta Lagna; Bruno Bergamasco; Lorenzo Pinessi; Innocenzo Rainero

1999-01-01

286

Observational study of erythrocyte protoporphyrin screening test for detecting low lead exposure in children: Impact of lowering the blood lead action threshold  

SciTech Connect

We examined a retrospective sample of 1800 children on whom both erythrocyte protoporphyrin (EP) and blood lead (BPb) measurements were taken. The primary objective was to ascertain whether EP is a cost-effective screening test for low but increased BPb concentrations and to establish the optimal thresholds. The data did not provide evidence of an EP threshold at low BPb concentrations; however, the data did show a significant age effect. A subset of 500 children for whom both EP and hematocrit data were available showed no correlation between those variables. Age-specific operating characteristic curves, total error, and cost analyses are presented. The latter sets bounds on the relative cost of EP testing, above which only BPb determination should be performed. The implications of these findings are discussed in light of impending changes in U.S. federal guidelines for preventing lead poisoning in young children.

Parsons, P.J.; Reilly, A.A.; Hussain, A. (New York State Department of Health, Albany (USA))

1991-02-01

287

INDRA, a 4? charged product detection array at GANIL  

Microsoft Academic Search

INDRA, a new and innovative highly segmented detector for light charged particles and fragments is described. It covers geometrically 90% of the 4? solid angle and has very low detection thresholds. The detector, operated under vacuum, is axially symmetric and segmented in 336 independent cells allowing efficient detection of high multiplicity events. Nucleus identification down to very low energy threshold

J. Pouthas; B. Borderie; R. Dayras; E. Plagnol; M. F. Rivet; F. Saint-Laurent; J. C. Steckmeyer; G. Auger; C. O. Bacri; S. Barbey; A. Barbier; A. Benkirane; J. Benlliure; B. Berthier; E. Bougamont; P. Bourgault; P. Box; R. Bzyl; B. Cahan; Y. Cassagnou; D. Charlet; J. L. Charvet; A. Chbihi; T. Clerc; N. Copinet; D. Cussol; M. Engrand; J. M. Gautier; Y. Huguet; O. Jouniaux; J. L. Laville; P. Le Botlan; A. Leconte; R. Legrain; P. Lelong; M. Le Guay; L. Martina; C. Mazur; P. Mosrin; L. Olivier; J. P. Passerieux; S. Pierre; B. Piquet; E. Plaige; E. C. Pollacco; B. Raine; A. Richard; J. Ropert; C. Spitaels; L. Stab; D. Sznajderman; L. Tassan-Got; J. Tillier; M. Tripon; P. Vallerand; C. Volant; P. Volkov; J. P. Wieleczko; G. Wittwer

1995-01-01

288

Automatic Threshold Circuit.  

National Technical Information Service (NTIS)

An automatic threshold circuit to establish a threshold that is a specified number of db above the input's rms frequency weighted noise value is described. The input is compared with the feedback threshold value, the result of which is coupled to a limite...

J. H. Bumgardner

1976-01-01

289

Threshold Concepts in Biochemistry  

ERIC Educational Resources Information Center

|Threshold concepts can be identified for any discipline and provide a framework for linking student learning to curricular design. Threshold concepts represent a transformed understanding of a discipline, without which the learner cannot progress and are therefore pivotal in learning in a discipline. Although threshold concepts have been…

Loertscher, Jennifer

2011-01-01

290

Stochastic resonance in threshold systems.  

PubMed

We consider signal processing in simple threshold systems with nonstationary additive and/or multiplicative noise. A discrete-time process with a small periodical signal masked by noise represents an input. The systems convert sampled input data to a nonstationary random point event flow carrying some information on an input signal. As it is shown in our previous study [M.M. Alibegov, Astron. Lett. 22, 564 (1996)], the Rayleigh spectral function of a random point event train estimates a signal-to-noise ratio (SNR) at selected frequencies. Based on these results, we compute a system response at signal frequencies as a function of threshold and input noise intensity. The threshold systems are shown to reveal stochastic resonance (SR), i.e., output SNR exhibits a maximum at resonant noise intensity (intensities) and threshold(s) at rather common conditions. We show that SR and Rayleigh spectral technique allow us to carry out numerical signal detection in data sets with noise. PMID:11969434

Alibegov, M M

1999-05-01

291

Low-energy electron detection in microcolumns  

SciTech Connect

Metal--semiconductor--metal (MSM) structures for the application as detectors for low-energy backscattered electrons in electron-beam microcolumns have been investigated. Realized Ti--Si--Ti MSM devices showed current gains of up to 200 for 1 keV electrons. An unsatisfying signal/dark current ratio made the reduction of the dark current necessary. Two different approaches to reduce the dark current were examined: varying the used contact metal and investigating MSM structures with two different contact metals for cathode and anode (asymmetric MSM structures). The accomplished reduction of more than two orders of magnitude demonstrated the possibility to achieve a signal/dark current ratio of 0.4. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

Fresser, H.S.; Prins, F.E.; Kern, D.P. [Institut fuer Angewandte Physik, Universitaet Tuebingen, Auf der Morgenstelle 10, D-72076 Tuebingen (Germany)

1995-11-01

292

Detecting leaks to reduce energy costs  

SciTech Connect

This article describes how analyzing boilerhouse data in its manufacturing plants and applying algorithmic techniques is helping an automobile manufacturer run its utility operations more efficiently. Ford Motor Co., based in Dearborn, Michigan, is realizing significant energy savings, reducing capital expenditures, and minimizing wastewater disposal costs by diagnosing and quantifying leaks in its compressed air, steam/condensate, and process water systems by applying algorithms developed by Cleveland-based CEC Consultants Inc. These algorithms make use of readily available--and often already installed--instruments, such as vortex shedding meters, chart recorders, and data loggers, to compare how much utility use is needed for assembly and manufacturing equipment with how much is being generated.

Valenti, M.

1995-07-01

293

The Detection of the High-Energy EAS Muon Component with the LST Detector of Kascade-Grande  

NASA Astrophysics Data System (ADS)

A Limited Streamer Tube (LST) detector system has been installed at the KASCADE-Grande experiment to study the Extensive Air Showers (EAS) muon component above a threshold of 2.4 GeV. The extended area of 255 m2 of the LST and the fine granularity of detection enables a detailed study of the muon spatial distribution in the very central zone of the air shower. A dedicated, fractal based analysis has been developed to take advantage of the observables of this detector setup. The sensitivity on cosmic rays mass and energy discrimination has been verified, based on 1.5 years of data collection by the KASCADE experiment.

Bercuci, A.; Antoni, T.; Apel, W. D.; Badea, F.; Bekk, K.; Bertaina, M.; Blümer, H.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Büttner, C.; Chiavassa, A.; Daumiller, K.; di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Feßler, F.; Ghia, P. L.; Gils, H. J.; Glasstetter, R.; Haungs, A.; Heck, D.; Hörandel, J. R.; Kampert, K.-H.; Klages, H. O.; Kolotaev, Y.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Müller, M.; Navarra, G.; Obenland, R.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu, M.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler, H.; Scholz, J.; Stümpert, M.; Thouw, T.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; Walkowiak, W.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zagromski, S.; Zimmermann, D.

294

Reexamination of the improved strong-field approximation: Low-energy structures in the above-threshold-ionization spectra for short-range potentials  

NASA Astrophysics Data System (ADS)

The improved strong-field approximation (ISFA) is a version of the strong-field approximation which takes into account an additional interaction of the ionized electron with the parent ion within the first Born approximation. The ISFA describes well the middle- and high-energy parts of the electron spectra in the above-threshold ionization process. We show, using an example of a short-range potential, that the ISFA is able to describe the low-energy structure in the energy spectra if it is calculated without additional approximations. We introduce two different forms of the T-matrix element which are appropriate for application of two widely used approximations: the saddle-point approximation [i.e., its more advanced version, the uniform approximation (UA)] and the pole approximation (PA). We show that both the PA and UA are not able to describe the low-energy structure. Furthermore, the UA describes better the plateau of the spectrum than the PA. We also identify the origin of a very-low-energy structure; it is connected to the laser-free (i.e., without exchange of the laser photons) electron forward scattering.

Miloševi?, D. B.

2013-08-01

295

Monte Carlo simulation of the cascade decay processes in gaseous boron initiated by photons with energies scanned through L- and K-ionization thresholds  

NASA Astrophysics Data System (ADS)

The Monte Carlo technique is applied to simulate the processes of the cascade relaxation of gaseous boron at atomic density of 2.5 × 1022 m-3 ionized by photons with the energies of 0.7-25 Ryd passing through a cylindrical interaction zone along its axis. The trajectories of electrons are simulated based on photoionization and electron-impact ionization cross sections calculated in the one-electron configuration-average Pauli-Fock approximation. Numbers of electrons and photons leaving the interaction zone per one initial photoionization, their energy spectra, the energy transferred to the medium and the probabilities of final ion formations are shown to change noticeably as the incident photon energy is scanned through boron atom ionization thresholds. These variations can be explained only if secondary electron-impact-produced processes are considered. The density of secondary events decreases when going from the zone axis to its border, and the profiles of the density along the radial direction are found to be similar for all the initial exciting photon energies.

Brühl, S.; Kochur, A. G.

2012-07-01

296

An efficient voice activity detection algorithm by combining statistical model and energy detection  

NASA Astrophysics Data System (ADS)

In this article, we present a new voice activity detection (VAD) algorithm that is based on statistical models and empirical rule-based energy detection algorithm. Specifically, it needs two steps to separate speech segments from background noise. For the first step, the VAD detects possible speech endpoints efficiently using the empirical rule-based energy detection algorithm. However, the possible endpoints are not accurate enough when the signal-to-noise ratio is low. Therefore, for the second step, we propose a new gaussian mixture model-based multiple-observation log likelihood ratio algorithm to align the endpoints to their optimal positions. Several experiments are conducted to evaluate the proposed VAD on both accuracy and efficiency. The results show that it could achieve better performance than the six referenced VADs in various noise scenarios.

Wu, Ji; Zhang, Xiao-Lei

2011-12-01

297

Low energy impact detection on carbon fiber reinforced materials  

SciTech Connect

Impact damages, even of small magnitude, affect the mechanical properties of a composite material by reducing its structural integrity. Low energy impacts are not always visible to the naked eye, and they need to be accurately localized for safety and quality reasons. The results of low energy impact detection (0.5--6.0 J) on carbon fiber reinforced materials, carried out with four different NDT techniques--visual, infrared, X-rays, and eddy current--are presented in this paper. Probability of detection (POD) curves are plotted to compare the potential of each technique in regards to carbon fiber reinforced materials. Inspection results have shown that eddy currents are well suited to detect and quantify low energy impacts in carbon fiber composites.

Gros, X.E. [Robert Gordon Univ., Aberdeen (United Kingdom)

1995-03-01

298

Observation of threshold energy and hysteresis in high current ion beam guiding and transmission through a micro-glass-capillary  

SciTech Connect

The energy dependent guiding of high current density (0.1-3 A/m{sup 2}) argon ion beams through a micro-glass-capillary is studied. It is observed that ion transmission through the capillary takes place only if its energy is greater than the retarding potential barrier, which depends upon the amount of charge deposited on the capillary inner wall. Foremost evidence of the observation that the transmitted current exhibits hysteresis with ion energy is presented. Particle in cell simulations carried out by solving Poisson's and Newton's force equation self-consistently, agree reasonably well with the experimental results.

Paul, Samit; Jayakiran, A.; Bhattacharjee, Sudeep [Department of Physics, Indian Institute of Technology, Kanpur, Uttar Pradesh 208016 (India)

2012-11-26

299

Measurement of the solar B8 neutrino rate with a liquid scintillator target and 3 MeV energy threshold in the Borexino detector  

NASA Astrophysics Data System (ADS)

We report the measurement of ?-e elastic scattering from B8 solar neutrinos with 3 MeV energy threshold by the Borexino detector in Gran Sasso (Italy). The rate of solar neutrino-induced electron scattering events above this energy in Borexino is 0.22±0.04(stat)±0.01(syst)cpd/100t, which corresponds to ?B8ES=2.4±0.4±0.1×106cm-2s-1, in good agreement with measurements from SNO and SuperKamiokaNDE. Assuming the B8 neutrino flux predicted by the high metallicity standard solar model, the average B8 ?e survival probability above 3 MeV is measured to be 0.29±0.10. The survival probabilities for Be7 and B8 neutrinos as measured by Borexino differ by 1.9?. These results are consistent with the prediction of the MSW-LMA solution of a transition in the solar ?e survival probability Pee between the low-energy vacuum-driven and the high-energy matter-enhanced solar neutrino oscillation regimes.

Bellini, G.; Benziger, J.; Bonetti, S.; Buizza Avanzini, M.; Caccianiga, B.; Cadonati, L.; Calaprice, F.; Carraro, C.; Chavarria, A.; Chepurnov, A.; Dalnoki-Veress, F.; D'Angelo, D.; Davini, S.; de Kerret, H.; Derbin, A.; Etenko, A.; Fomenko, K.; Franco, D.; Galbiati, C.; Gazzana, S.; Ghiano, C.; Giammarchi, M.; Goeger-Neff, M.; Goretti, A.; Guardincerri, E.; Hardy, S.; Ianni, Aldo; Ianni, Andrea; Joyce, M.; Korga, G.; Kryn, D.; Laubenstein, M.; Leung, M.; Lewke, T.; Litvinovich, E.; Loer, B.; Lombardi, P.; Ludhova, L.; Machulin, I.; Manecki, S.; Maneschg, W.; Manuzio, G.; Meindl, Q.; Meroni, E.; Miramonti, L.; Misiaszek, M.; Montanari, D.; Muratova, V.; Oberauer, L.; Obolensky, M.; Ortica, F.; Pallavicini, M.; Papp, L.; Perasso, L.; Perasso, S.; Pocar, A.; Raghavan, R. S.; Ranucci, G.; Razeto, A.; Re, A.; Risso, P.; Romani, A.; Rountree, D.; Sabelnikov, A.; Saldanha, R.; Salvo, C.; Schönert, S.; Simgen, H.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Sukhotin, S.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Vignaud, D.; Vogelaar, R. B.; von Feilitzsch, F.; Winter, J.; Wojcik, M.; Wright, A.; Wurm, M.; Xu, J.; Zaimidoroga, O.; Zavatarelli, S.; Zuzel, G.; Borexino Collaboration

2010-08-01

300

Nuclear reactions in deuterated palladium and rhenium irradiated by ? quanta with a continuous spectrum at a threshold energy of 23 MeV in dense deuterium gas  

NASA Astrophysics Data System (ADS)

The element composition of Pd and Re samples in dense deuterium gas irradiated by ? quanta with a continuous spectrum and a threshold energy of 23 MeV has been studied. Considerable anomalies are discovered in the structure and element composition of irradiated samples. Substantial changes are observed at both ends of the Pd and Re wires in the form of blowouts of molten metal with a complex chemical composition resembling congealed solar protuberances. The surface of Pd and Re wires proved to be covered with 1-2-?m particles predominantly composed of rhenium oxide Re2O7. Near the cracks on the surface, these particles are crystallized in the form of small hexagonal crystallites composed of rhenium, carbon, and oxygen. The entire surface of rhenium is cracked and covered by a thick layer of the Re x C y compound. A brief description of the phenomenological model of nuclear reactions leading to the observed anomalies is given.

Didyk, A. Yu.; Wi?niewski, R.

2013-07-01

301

Differential cross sections in electron - hydrogen scattering at energies lying between the n = 3 and n = 4 thresholds  

NASA Astrophysics Data System (ADS)

Two independent calculations have been carried out to obtain the differential cross sections (DCS) for the excitation of n = 2 and 3 states from the ground state of hydrogen at electron impact energies lying between the n = 3 and n = 4 thresholds. They are the 15-state R-matrix calculation of Fon et al and the algebraic variational method of Wang and Callaway. The cross sections show complicated and irregular structures associated with overlapping resonances in different partial waves. Resonance analysis has been carried out. In the absence of experiments and other theoretical calculations, the 15-state R-matrix calculation is used to describe the shape of the DCS while the absolute magnitude is estimated by the algebraic variational method.

Ratnavelu, Kuru; Wang, Y. D.; Fon, W. C.; Callaway, J.; Aggarwal, K. M.

1996-06-01

302

Evidence for an anaerobic syntrophic benzoate degradation threshold and isolation of the syntrophic benzoate degrader  

SciTech Connect

An anaerobic, motile, gram-negative, rod-shaped, syntrophic. benzoate-degrading bacterium, strain SB. was isolated in pure culture with crotonate as the energy source. Benzoate was degraded only in association with an H{sub 2}-using bacterium. The kinetics of benzoate degradation by cell suspensions of strain SB in coculture with Desulfovibrio strain G-11 was studied by using progress curve analysis. The coculture degraded benzoate to a threshold concentration of 214 nM to 6.5 {mu}M, with no further benzoate degradation observed even after extended incubation times. The value of the threshold depended on the amount of benzoate added and, consequently, the amount of acetate produced. The addition of sodium acetate. but not that of sodium chloride, affected the threshold value; higher acetate concentrations resulted in higher threshold values for benzoate. When a cell suspension that had reached a threshold benzoate concentration was reamended with benzoate, benzoate was used without a lag. The hydrogen partial pressure was very low and formate was not detected in cell suspensions that had degraded benzoate to a threshold value. The Gibbs free energy change calculations showed that the degradation of benzoate was favorable when the threshold was reached. These studies showed that the threshold for benzoate degradation was not caused by nutritional limitations. the loss of metabolic activity, or inhibition by hydrogen or formate. The data are consistent with a thermodynamic explanation for the existence of a threshold, but a kinetic explanation based on acetate inhibition may also account for the existence of a threshold.

Hopkins, B.T.; McInerney, M.J.; Warikoo, V. [Univ. of Oklahoma, Norman, OK (United States)

1995-02-01

303

Evidence for anaerobic syntrophic benzoate degradation threshold and isolation of the syntrophic benzoate degrader.  

PubMed Central

An anaerobic, motile, gram-negative, rod-shaped, syntrophic, benzoate-degrading bacterium, strain SB, was isolated in pure culture with crotonate as the energy source. Benzoate was degraded only in association with an H2-using bacterium. The kinetics of benzoate degradation by cell suspensions of strain SB in coculture with Desulfovibrio strain G-11 was studied by using progress curve analysis. The coculture degraded benzoate to a threshold concentration of 214 nM to 6.5 microM, with no further benzoate degradation observed even after extended incubation times. The value of the threshold depended on the amount of benzoate added and, consequently, the amount of acetate produced. The addition of sodium acetate, but not that of sodium chloride, affected the threshold value; higher acetate concentrations resulted in higher threshold values for benzoate. When a cell suspension that had reached a threshold benzoate concentration was reamended with benzoate, benzoate was used without a lag. The hydrogen partial pressure was very low and formate was not detected in cell suspensions that had degraded benzoate to a threshold value. The Gibbs free energy change calculations showed that the degradation of benzoate was favorable when the threshold was reached. These studies showed that the threshold for benzoate degradation was not caused by nutritional limitations, the loss of metabolic activity, or inhibition by hydrogen or formate. The data are consistent with a thermodynamic explanation for the existence of a threshold, but a kinetic explanation based on acetate inhibition may also account for the existence of a threshold.

Hopkins, B T; McInerney, M J; Warikoo, V

1995-01-01

304

Nasal pungency, odor, and eye irritation thresholds for homologous acetates.  

PubMed

We measured detection thresholds for nasal pungency (in anosmics), odor (in normosmics) and eye irritation employing a homologous series of acetates: methyl through octyl acetate, decyl and dodecyl acetate. All anosmics reliably detected the series up to heptyl acetate. Only the anosmics without smell since birth (congenital) reliably detected octyl acetate, and only one congenital anosmic detected decyl and dodecyl acetate. Anosmics who lost smell from head trauma proved to be selectively less sensitive. As expected, odor thresholds lay well below pungency thresholds. Eye irritation thresholds for selected acetates came close to nasal pungency thresholds. All three types of thresholds decreased logarithmically with carbon chain length, as previously seen with homologous alcohols and as seen in narcotic and toxic phenomena. Results imply that nasal pungency for these stimuli rests upon a physical, rather than chemical, interaction with susceptible mucosal structures. When expressed as thermodynamic activity, nasal pungency thresholds remain remarkably constant within and across the homologous series of acetates and alcohols. PMID:1763117

Cometto-Muñiz, J E; Cain, W S

1991-08-01

305

Echo thresholds for reflections from acoustically diffusive architectural surfaces.  

PubMed

When sound reflects from an irregular architectural surface, it spreads spatially and temporally. Extensive research has been devoted to prediction and measurement of diffusion, but less has focused on its perceptual effects. This paper examines the effect of temporal diffusion on echo threshold. There are several notable differences between the waveform of a reflection identical to the direct sound and one from an architectural surface. The onset and offset are damped and the energy is spread in time; hence, the reflection response has a lower peak amplitude, and is decorrelated from the direct sound. The perceptual consequences of these differences are previously undocumented. Echo threshold tests are conducted with speech and music signals, using direct sound and a simulated reflection that is either identical to the direct sound or has various degrees of diffusion. Results indicate that for a speech signal, diffuse reflections are less easily detectable as a separate auditory event than specular reflections of the same total energy. For a music signal, no differences are observed between the echo thresholds for reflections with and without temporal diffusion. Additionally, echo thresholds are found to be shorter for speech than for music, and shorter for spatialized than for diotic presentation of signals. PMID:24116414

Robinson, Philip W; Walther, Andreas; Faller, Christof; Braasch, Jonas

2013-10-01

306

Semi-exclusive structure functions and inclusive form factors for ed{yields}e{sup '}{pi}NN in the energy region from threshold up to 500 MeV  

SciTech Connect

The separated structure functions R{sub L}, R{sub T}, R{sub LT}, and R{sub TT} governing the semi-exclusive differential cross section for the d(e,e{sup '}{pi})NN reaction are evaluated in the energy region from threshold up to 500 MeV. We present results for both the neutral and the charged pion production channels in a variety of kinematic settings. For the elementary pion electroproduction operator, the realistic unitary isobar MAID-2003 model is used which gives a good description of the process on the free nucleon. The completely inclusive form factors, which determine the inclusive differential cross section when only the scattered electron is detected, are also computed. It has been found that the structure functions and form factors reveal clear differences between the production dynamics for the {pi}{sup 0} and {pi}{sup {+-}} pions. Considerable dependencies of the structure functions and form factors on the pion angle and virtual photon lab-energy are found. The predicted results are found to be insensitive to the potential model used for the deuteron wave function.

Darwish, E.M. [Physics Department, College of Applied Science, Taibah University, P.O. Box 1343, Al-Madinah Al-Munawarah (Saudi Arabia); Physics Department, Faculty of Science, Sohag University, Sohag 82524 (Egypt)], E-mail: eeddarwish@yahoo.com; Al-Thoyaib, S.S. [Physics Department, Faculty of Science, Qassim University, Buraydah 51452, P.O. Box 6644 (Saudi Arabia)], E-mail: salthoyaib@yahoo.com

2009-08-15

307

Near-threshold photoproduction of ? mesons from deuterium  

NASA Astrophysics Data System (ADS)

We report the first, kinematically-complete measurement of the differential cross section of ?-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, K+ and K- near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections d?dt for the initial photon energy range of 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. Our finding is different from recent LEPS results on ?-meson photoproduction from deuterium in a similar incident photon energy range, but in a different momentum transfer region.

Clas Collaboration; Qian, X.; Chen, W.; Gao, H.; Hicks, K.; Kramer, K.; Laget, J. M.; Mibe, T.; Qiang, Y.; Stepanyan, S.; Tedeschi, D. J.; Xu, W.; Adhikari, K. P.; Amaryan, M.; Anghinolfi, M.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bellis, M.; Biselli, A. S.; Bookwalter, C.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Careccia, S. L.; Carman, D. S.; Cole, P. L.; Collins, P.; Crede, V.; D'Angelo, A.; Daniel, A.; Dashyan, N.; de Vita, R.; de Sanctis, E.; Deur, A.; Dey, B.; Dhamija, S.; Djalali, C.; Doughty, D.; Dupre, R.; Egiyan, H.; El Alaoui, A.; Eugenio, P.; Fegan, S.; Gabrielyan, M. Y.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Gothe, R. W.; Graham, L.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Hassall, N.; Holtrop, M.; Ilieva, Y.; Ireland, D. G.; Jawalkar, S. S.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Konczykowski, P.; Kubarovsky, V.; Kuleshov, S. V.; Kuznetsov, V.; Livingston, K.; Martinez, D.; Mayer, M.; McAndrew, J.; McCracken, M. E.; McKinnon, B.; Meyer, C. A.; Mikhailov, K.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Moreno, B.; Moriya, K.; Morrison, B.; Moutarde, H.; Munevar, E.; Nadel-Turonski, P.; Ni, A.; Niccolai, S.; Niculescu, I.; Niroula, M. R.; Osipenko, M.; Ostrovidov, A. I.; Paremuzyan, R.; Park, K.; Park, S.; Pereira, S. Anefalos; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, E. S.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Taylor, C. E.; Tkachenko, S.; Ungaro, M.; Vernarsky, B.; Vineyard, M. F.; Voutier, E.; Weinstein, L. B.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, B.; Zhao, Z. W.

2011-02-01

308

Fraud detection in electrical energy consumers using rough sets  

Microsoft Academic Search

Rough set is an emergent technique of soft computing that have been used in many knowledge discovery in database applications. This work describes an application of rough sets in the fraud detection of electrical energy consumers. From an information system, rough sets concept of reduct was used to reduce the number of conditional attributes and the minimal decision algorithm (MDA)

José Edison Cabral; Edgar M. Gontijo

2004-01-01

309

Microwave detection of Ultra-High Energy Cosmic Rays  

NASA Astrophysics Data System (ADS)

A novel detection technique for Ultra-High Energy Cosmic Rays based on microwave emission from the extensive air showers may provide large area coverage with 100% duty cycle at low cost. The status and prospects of several complementary R&D projects for GHz detectors is reviewed.

Privitera, P.

2011-09-01

310

Energy-driven detection scheme with guaranteed accuracy  

Microsoft Academic Search

This is our first step towards a holistic investigation of the minimum energy for wireless sensor network (WSN) to perform a specific function. We consider wireless sensor net works that perform an event detection function. Each sensor node will repetitively collect a 1-bit information regarding whether the event occurs or not in its neighborhood. A fusion center will make the

Lige Yu; Lin Yuan; Gang Qu; Anthony Ephremides

2006-01-01

311

Detection of ultrahigh-energy cosmic rays and neutrinos by a lunar nanosatellite-borne radio receiver  

NASA Astrophysics Data System (ADS)

The feasibility of ultrahigh-energy cosmic ray and neutrino detection by a lunar nanosatellite-borne radio receiver is discussed. The estimated values of the energy threshold and event rate for cosmic ray detection are found to be Eth(CR) ? 1018 eV, N(CR, E ? 1019 eV) ? a few hundreds of events per day, and N(CR, E ? 1020 eV) is more than thousand events per year. Cosmic -ray particle energy and arrival angles will be measured. Thus, the proposed experiment will have very high scientific potential in detection of ultrahigh-energy cosmic rays comparable to that of the most ambitious proposals like EUSO and OWL, the cost being one or two orders of magnitude lower. Moreover, neutrinos with E > Eth(neutrino) ? 5\\cdot 1018 eV can be also detected in the same experiment at the rate of a few to a few hundreds of events per year depending on the neutrino-source model. The basic design of the antenna system and concept of the registration channel are presented.

Chechin, V. A.; Lomonosov, B. N.; Pichkhadze, K. M.; Poluhina, N. G.; Ryabov, V. A.; Sysoev, V. K.; Tsarev, V. A.

312

NMDA receptor activation accelerates ischemic energy depletion in the hippocampal slice and the demonstration of a threshold for ischemic damage to protein synthesis.  

PubMed

Energy depletion is a primary factor initiating ischemic damage to neurons. In a separate report, we demonstrated that in vitro ischemia inhibits protein synthesis in the CA1 pyramidal neurons of the hippocampal slice via a mechanism involving extracellular calcium and N-methyl-D-aspartate (NMDA) receptor activation during the ischemic episode. In this study, we tested whether these agents accelerated the ischemic energy depletion beyond tolerable levels. ATP and phosphocreatine (PCr) were measured immediately after different durations of in vitro ischemia in the presence or absence of calcium and the NMDA receptor antagonist ketamine. The results support the contention that extracellular calcium does not contribute to the ischemic energy depletion. NMDA receptor activation accelerates the fall in ATP and PCr, but only during the first 45 s of the ischemia. Using protein synthesis inhibition as a functional indicator of ischemic damage in the hippocampal slice, we demonstrated that greater than 2 min of ischemia is necessary to inhibit protein synthesis. Thus, this threshold duration of ischemia indicates that events occurring between 2 and 5 min ischemia result in a prolonged protein synthesis inhibition. PMID:2158012

Raley, K M; Lipton, P

1990-03-01

313

PREFACE: Sixth Symposium on Large TPCs for Low Energy Rare Event Detection  

NASA Astrophysics Data System (ADS)

For the sixth time the International Symposium on large TPCs for Low-Energy Rare-Event Detection has been organized in Paris on 17-19 December 2012. As for the previous conference, we were welcomed in the Astroparticle and Cosmology Laboratory (APC). Around one hundred physicists from all over the world gathered to discuss progress in the dark matter and low-energy neutrino search. The new results from the LHC were also widely discussed. The Higgs discovery at 125 GeV, without any sign of other new heavy particles, does not provide us with any information on the nature of dark mater. Alternatives to the favored SUSY model, in which the role of the WIMP is played by a stable neutralino, predict low mass candidates below a few GeV. Developing low threshold detectors at sub-keV energies becomes mandatory, and interest for Axion or Axion-like particles as dark matter is revived. We have seen increasing activity in the field and new infrastructures for these searches have been developed. We heard news of activities in the Canfranc laboratory in Spain, Jinping in China, SURF in the USA and about the extension project of Fréjus (LSM) laboratory. We would like to thank the organizing and advisory committees as well as the session chairpersons: J Zinn-Justin, G Wormser, D Nygren, G Chardin, F Vannucci, D Attié, T Patzak and S Jullian. I Giomataris, P Colas and I G Irastorza Group picture

Irastorza, Igor G.; Colas, Paul; Giomataris, Ioannis

2013-10-01

314

Radar CFAR thresholding in clutter and multiple target situations  

Microsoft Academic Search

Radar detection procedures involve the comparison of the received signal amplitude to a threshold. In order to obtain a constant false-alarm rate (CFAR), an adaptive threshold must be applied reflecting the local clutter situation. The cell averaging approach, for example, is an adaptive procedure. A CFAR method is discussed using as the CFAR threshold one single value selected from the

Hermann Rohling

1983-01-01

315

Threshold anomaly in doublet nd-scattering.  

National Technical Information Service (NTIS)

The doublet nd-scattering amplitude behaviour near the three-particle threshold is studied analytically and numerically. The scattering amplitude possesses an anomaly caused by the small energy of singlet deuteron virtual level. The anomaly manifests itse...

D. V. Shapoval I. V. Simenog

1988-01-01

316

Bayesian Threshold Estimation  

ERIC Educational Resources Information Center

|Bayesian estimation of a threshold time (hereafter simply threshold) for the receipt of impulse signals is accomplished given the following: 1) data, consisting of the number of impulses received in a time interval from zero to one and the time of the largest time impulse; 2) a model, consisting of a uniform probability density of impulse time…

Gustafson, S. C.; Costello, C. S.; Like, E. C.; Pierce, S. J.; Shenoy, K. N.

2009-01-01

317

Hierarchical Threshold Secret Sharing  

Microsoft Academic Search

We consider the problem of threshold secret sharing in groups with hierarchical structure. In such settings, the secret is shared among a group of participants that is partitioned into levels. The access structure is then determined by a sequence of threshold requirements: a subset of participants is authorized if it has at least k0 members from the highest level, as

Tamir Tassa

2004-01-01

318

Prospects for detecting gamma-ray bursts at very high energies with the Cherenkov Telescope Array  

NASA Astrophysics Data System (ADS)

We discuss the prospects for the detection of gamma-ray bursts (GRBs) by the Cherenkov Telescope Array (CTA), the next generation, ground-based facility of imaging atmospheric Cherenkov telescopes (IACTs) operating above a few tens of GeV. By virtue of its fast slewing capabilities, the lower energy threshold compared to current IACTs, and the much larger effective area compared to satellite instruments, CTA can measure the spectra and variability of GRBs with excellent photon statistics at multi-GeV energies, which would revolutionize our understanding of the physics of GRBs, test their validity as the origin of ultrahigh-energy cosmic rays and provide powerful probes of the extragalactic background light as well as Lorentz-invariance violation. Employing a model of the GRB population whose properties are broadly consistent with observations by the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) on-board Fermi, we simulate follow-up observations of GRBs with the Large Size Telescopes (LSTs), the component of CTA with the fastest slew speed and the best sensitivity at energies below a few hundred GeV. For our fiducial assumptions, we foresee that the LSTs can detect ˜0.1 GRBs per year during the prompt phase and ˜0.5 GRBs per year in the afterglow phase, considering only one array site and both GBM and the Space-based multi-band astronomical Variable Object Monitor (SVOM) as the alert instruments. The detection rates can be enhanced by a factor of about 5 and 6 for the prompt emission and the afterglow, respectively, assuming two array sites with the same sensitivity and that the GBM localization error can be reduced to less than 1°. The expected distribution of redshift and photon counts is presented, showing that despite the modest event rate, hundreds or more of multi-GeV photons can be anticipated from a single burst once they are detected. We also study how the detection rate depends on the intrinsic GRB properties and the delay time between the burst trigger and the follow-up observation.

Kakuwa, Jun; Murase, Kohta; Toma, Kenji; Inoue, Susumu; Yamazaki, Ryo; Ioka, Kunihito

2012-09-01

319

Resonant energy transfer based biosensor for detection of multivalent proteins.  

SciTech Connect

We have developed a new fluorescence-based biosensor for sensitive detection of species involved in a multivslent interaction. The biosensor system utilizes specific interactions between proteins and cell surface receptors, which trigger a receptor aggregation process. Distance-dependent fluorescence self-quenching and resonant energy transfer mechanisms were coupled with a multivalent interaction to probe the receptor aggregation process, providing a sensitive and specific signal transduction method for such a binding event. The fluorescence change induced by the aggregation process can be monitored by different instrument platforms, e.g. fluorimetry and flow cytometry. In this article, a sensitive detection of pentavalent cholera toxin which recognizes ganglioside GM1 has been demonstrated through the resonant energy transfer scheme, which can achieve a double color change simultaneously. A detection sensitivity as high as 10 pM has been achieved within a few minutes (c.a. 5 minutes). The simultaneous double color change (an increase of acceptor fluorescence and a decrease of donor fluorescence intensity) of two similar fluorescent probes provides particularly high detection reliability owing to the fact that they act as each other's internal reference. Any external perturbation such as environmental temperature change causes no significant change in signal generation. Besides the application for biological sensing, the method also provides a useful tool for investigation of kinetics and thermodynamics of a multivalent interaction. Keywords: Biosensor, Fluorescence resonant energy transfer, Multivalent interaction, Cholera Toxin, Ganglioside GM1, Signal Transduction

Song, X. (Xuedong); Swanson, Basil I.

2001-01-01

320

Studies of photoionization dynamics of CH, NH, and OH radicals at near-threshold photoelectron kinetic energies  

SciTech Connect

We discuss results of theoretical studies of rotationally resolved photoelectron spectra of the CH, NH, and OH radicals, including predictions of zero-kinetic-energy (ZEKE) spectra for molecular ions produced via resonance enhanced multiphoton ionization. The influence of dynamical features such as Cooper minima, orbital evolution, and l mixing are examined for photoionization of the 3p[sigma] Rydberg orbital in these radicals. We also make specific predictions for the photoelectron spectra for each molecule within the context of current experimental capabilities. 29 refs., 11 figs.

Wang, K.; Stephens, J.A.; McKoy, V. (California Inst. of Technology, Pasadena, CA (United States))

1994-01-13

321

Neutrino and WIMP detection with CLEAN  

Microsoft Academic Search

CLEAN is an approach to the detection of weakly interacting particles of astrophysical significance, combining large mass and low energy threshold. CLEAN is capable of detecting low energy solar neutrinos, weakly interacting massive particles (WIMPs), and neutrinos released from supernovas. Because liquid neon has a high scintillation yield, has no long-lived radioactive isotopes, and can be easily purified using cold

Daniel McKinsey; Walter Lippincott; James Nikkel; Andrew Hime; Mark Boulay; Jeff Lidgard; Kevin Coakley; Edward Kearns

2004-01-01

322

Limit on the Detectability of the Energy Scale of Inflation  

NASA Astrophysics Data System (ADS)

We show that the polarization of the cosmic microwave background can be used to detect gravity waves from inflation if the energy scale of inflation is above 2 x10(sup 15) GeV . These gravity waves generate polarization patterns with a curl, whereas (to first order in perturbation theory) density perturbations do not. The limiting "noise" arises from the second-order generation of curl from density perturbations, or rather residuals from its subtraction. We calculate optimal sky coverage and detectability limits as a function of detector sensitivity and observing time.

Knox, Lloyd; Song, Yong-Seon

2002-07-01

323

Measurement and model analysis of (n,x?) cross sections for Cr, Fe, 59Co, and 58,60Ni from threshold energy to 150 MeV  

NASA Astrophysics Data System (ADS)

Neutron reactions that produce ? particles have been investigated experimentally and analyzed by reaction model calculations for incident neutron energies from threshold to 150 MeV on elemental chromium and iron. The cross sections were measured at the Los Alamos Neutron Science Center by direct observation of ? particles. Previous data on isotopes 59Co and 58,60Ni were also included in the analysis. The model calculations are made for both statistical decay and pre-equilibrium processes. This study particularly focuses on the pre-equilibrium cluster emission, which is described by the clustering exciton model of Iwamoto and Harada. We calculate the ?-particle formation factors numerically without any of the approximations that appeared in the original model. The model parameter ?R, the nuclear surface area where the pickup reaction may occur, is determined by fitting the calculated ?-particle energy spectra to experimental data. The calculated ?-particle-production cross sections agree well with the measured data, except for the Cr case. With a simple sensitivity study for the level density parameters, it is reported that relatively small changes in the level density parameters improve the reproduction of experimental data significantly. Our realistic model calculations for the pre-equilibrium process shed light on uncertainties in the nuclear level densities in statistical decay calculation.

Kunieda, S.; Haight, R. C.; Kawano, T.; Chadwick, M. B.; Sterbenz, S. M.; Bateman, F. B.; Wasson, O. A.; Grimes, S. M.; Maier-Komor, P.; Vonach, H.; Fukahori, T.; Watanabe, Y.

2012-05-01

324

Threshold bubble chamber for measurement of knock-on DT neutron tails from magnetic and inertial confinement experiments  

SciTech Connect

We propose a new {open_quotes}threshold{close_quotes} bubble chamber detector for measurement of knock-on neutron tails. These energetic neutrons result from fusion reactions involving energetic fuel ions created by alpha knock-on collisions in tokamak and other magnetic confinement experiments, and by both alpha and neutron knock-on collisions in inertial confinement fusion (ICF) experiments. The energy spectrum of these neutrons will yield information on the alpha population and energy distribution in tokamaks, and on alpha target physics and {rho}R measurements in ICF experiments. The bubble chamber should only detect neutrons with energies above a selectable threshold energy controlled by the bubble chamber pressure. The bubble chamber threshold mechanism, detection efficiency, and proposed applications to the International Thermonuclear Experimental Reactor (ITER) and National Ignition Facility (NIF) experiments will be discussed.

Fisher, R.K. [General Atomics, San Diego, CA (United States); Zaveryaev, V.S. [Russian Research Centre, Moscow (Russian Federation). Kurchatov Institute; Trusillo, S.V. [Russian Federal Nuclear Centre, Arzamas (Russian Federation). Experimental Physics Institute

1996-07-01

325

AUDIBILITY THRESHOLDS OF THE BLUE JAY  

Microsoft Academic Search

The audibility thresholds of two Blue Jays were measured behaviorally using operant conditioning and psychophysical techniques. The jays responded to pure tones between 0.25 and 10 kHz. Their thresholds are similar to those reported for seven other passerines. This indicates that passerines are somewhat less sensitive than man in the detection of sounds in the 1 to 4 kHz range

STEVEN M. COHEN; WILLIAM C. STEBBINS; DAVID B. MOODY

1978-01-01

326

Detection and Analysis of Threats to the Energy Sector: DATES  

SciTech Connect

This report summarizes Detection and Analysis of Threats to the Energy Sector (DATES), a project sponsored by the United States Department of Energy and performed by a team led by SRI International, with collaboration from Sandia National Laboratories, ArcSight, Inc., and Invensys Process Systems. DATES sought to advance the state of the practice in intrusion detection and situational awareness with respect to cyber attacks in energy systems. This was achieved through adaptation of detection algorithms for process systems as well as development of novel anomaly detection techniques suited for such systems into a detection suite. These detection components, together with third-party commercial security systems, were interfaced with the commercial Security Information Event Management (SIEM) solution from ArcSight. The efficacy of the integrated solution was demonstrated on two testbeds, one based on a Distributed Control System (DCS) from Invensys, and the other based on the Virtual Control System Environment (VCSE) from Sandia. These achievements advance the DOE Cybersecurity Roadmap [DOE2006] goals in the area of security monitoring. The project ran from October 2007 until March 2010, with the final six months focused on experimentation. In the validation phase, team members from SRI and Sandia coupled the two test environments and carried out a number of distributed and cross-site attacks against various points in one or both testbeds. Alert messages from the distributed, heterogeneous detection components were correlated using the ArcSight SIEM platform, providing within-site and cross-site views of the attacks. In particular, the team demonstrated detection and visualization of network zone traversal and denial-of-service attacks. These capabilities were presented to the DistribuTech Conference and Exhibition in March 2010. The project was hampered by interruption of funding due to continuing resolution issues and agreement on cost share for four months in 2008. This resulted in delays in finalizing agreements with commercial partners, and in particular the Invensys testbed was not installed until December 2008 (as opposed to the March 2008 plan). The project resulted in a number of conference presentations and publications, and was well received when presented at industry forums. In spite of some interest on the part of the utility sector, we were unfortunately not able to engage a utility for a full-scale pilot deployment.

Alfonso Valdes

2010-03-31

327

A hydrophone prototype for ultra high energy neutrino acoustic detection  

NASA Astrophysics Data System (ADS)

The design of an air-backed fiber-optic hydrophone is presented. With respect to the previous models this prototype is optimized to provide a bandwidth sufficiently large to detect acoustic signals produced by high energy hadronic showers in water. In addiction to the geometrical configuration and to the choice of the materials, the preliminary results of the measured performances in air are presented.

Cotrufo, A.; Plotnikov, A.; Yershova, O.; Anghinolfi, M.; Piombo, D.

2009-06-01

328

Dual energy detection of weapons of mass destruction  

NASA Astrophysics Data System (ADS)

There is continuing plans and actions from terrorists to use "violence to inculcate fear with intent to coerce or try to intimidate governments or societies in the pursuit of goals that are generally political, religious or ideological." (Joint Pub 3-07.2) One can characterize the types of attacks and plan to interdict terrorist actions before they become crises. This paper focuses on Radiological (RDD) and Nuclear (WMD) threats. The X-ray inspection process and the use of dual-energy imaging will interdict materials for WMDs. Listed herewith is "several major characteristics that one can exploit for the detection. First, both WMDs and RDDs are radioactive. Therefore, one can hope to detect radiation coming from the containers to identify the threat. However since uranium and plutonium are largely self-shielding and since lead can be used to shield and hide these substances, passive detection of emitted radiation can be easily defeated. An important second characteristic is that WMDs and shielded dirty bombs contain materials with very high atomic numbers. Since normal commerce rarely contains materials with atomic numbers higher than that of iron, dual-energy imaging technology can detect such materials automatically, for the successful interdiction of WMDs and dirty bombs". (Bjorkolm 2005)

Budner, Gregory J.

2006-04-01

329

Towards a Low Threshold SuperCDMS Experiment  

NASA Astrophysics Data System (ADS)

Astrophysical evidence points to the existence of particle dark matter that comprises the majority of the mass of the universe. A natural candidate for these particles are Weakly Interacting Massive Particles, or WIMPs. Lately there has been much interest in dark matter search experiments for low mass WIMPs. Detection of WIMP dark matter with mass below 20 GeV/c^2 requires a low-energy trigger threshold. However, lowering the trigger threshold also makes us sensitive to triggering on random noise which can hamper livetime. In order to minimize triggering on this random noise the original trigger filters for SuperCDMS were replaced with improved filters that reduce the amplitude of random noise substantially compared to an event-generated signal, thus allowing us to lower the trigger thresholds without the livetime penalty we would otherwise accrue. An overview of how this was accomplished as well as post-triggering methods of noise discrimination will be discussed. Predictions for the improved low thresholds will be compared to data, and the impact on a low mass WIMP search will be described.

Welliver, Bradford

2013-04-01

330

Thresholds in conservation effectiveness under climate change  

Microsoft Academic Search

We describe a new approach to conservation that derives from the effect of energy on ecosystem properties and then evaluate potential threshold responses of conservation effectiveness under climate change. Many tests of species energy theory provide evidence that species richness varies with measures of energy such as net primary productivity (NPP). Across continents, this relationship is most often unimodal, with

A. Hansen; L. Phillips

2007-01-01

331

Quantum threshold group signature  

NASA Astrophysics Data System (ADS)

In most situations, the signer is generally a single person. However, when the message is written on behalf of an organization, a valid message may require the approval or consent of several persons. Threshold signature is a solution to this problem. Generally speaking, as an authority which can be trusted by all members does not exist, a threshold signature scheme without a trusted party appears more attractive. Following some ideas of the classical Shamir’s threshold signature scheme, a quantum threshold group signature one is proposed. In the proposed scheme, only t or more of n persons in the group can generate the group signature and any t - 1 or fewer ones cannot do that. In the verification phase, any t or more of n signature receivers can verify the message and any t - 1 or fewer receivers cannot verify the validity of the signature.

Yang, Yuguang; Wen, Qiaoyan

2008-10-01

332

Local visual energy mechanisms revealed by detection of global patterns.  

PubMed

A central goal of visual neuroscience is to relate the selectivity of individual neurons to perceptual judgments, such as detection of a visual pattern at low contrast or in noise. Since neurons in early areas of visual cortex carry information only about a local patch of the image, detection of global patterns must entail spatial pooling over many such neurons. Physiological methods provide access to local detection mechanisms at the single-neuron level but do not reveal how neural responses are combined to determine the perceptual decision. Behavioral methods provide access to perceptual judgments of a global stimulus but typically do not reveal the selectivity of the individual neurons underlying detection. Here we show how the existence of a nonlinearity in spatial pooling does allow properties of these early mechanisms to be estimated from behavioral responses to global stimuli. As an example, we consider detection of large-field sinusoidal gratings in noise. Based on human behavioral data, we estimate the length and width tuning of the local detection mechanisms and show that it is roughly consistent with the tuning of individual neurons in primary visual cortex of primate. We also show that a local energy model of pooling based on these estimated receptive fields is much more predictive of human judgments than competing models, such as probability summation. In addition to revealing underlying properties of early detection and spatial integration mechanisms in human cortex, our findings open a window on new methods for relating system-level perceptual judgments to neuron-level processing. PMID:22423090

Morgenstern, Yaniv; Elder, James H

2012-03-14

333

Hierarchical Threshold Secret Sharing  

Microsoft Academic Search

We consider the problem of threshold secret sharing in groups with hierarchical structure. In such settings, the secret is\\u000a shared among a group of participants that is partitioned into levels. The access structure is then determined by a sequence\\u000a of threshold requirements: a subset of participants is authorized if it has at least k0 0 members from the highest level,

Tamir Tassa

2007-01-01

334

Threshold detection of radar signals off the sea surface in non-Gaussian clutter and deterministic interference: II - statistical analysis of ROI surface data  

SciTech Connect

The purpose of this report is to motivate and outline a program of data analysis, for data obtained from radar returns from ocean surfaces perturbed by internal waves and wind-wave interactions. The ultimate aims of this analysis are to provide the appropriate statistics of the signals returned from these ocean surfaces for: (1) use in implementing and evaluating optimum and near-optimum signal processing procedures for detecting and evaluating (i.e., measuring) these internal wave effects and, (2) to provide quantitative physical insight into both the surface scatter and subsurface mechanisms which determine the received radar signals. Here the focus is initially on the needed statistics of the radar returns. These are primarily: (i) the (instantaneous) amplitude and envelope probability densities, (pdf`s) and distributions (PDFS) of the returns and, (ii) analogous statistics for the intensities (associated with the pixel data). Also required are: (iii) space-time covariance data of the returns, for further improvement of detection capabilities. Preliminary evidence and earlier experiments suggest that these data [(i), (ii)] are nongaussian and strongly so at times. This in turn, if not properly taken into account, can greatly degrade signal detection in the usual weak-signal regimes [1],[2].

Middleton, D.

1996-05-02

335

Detecting energy emissions from a rotating black hole.  

PubMed

The rotational energy of a black hole surrounded by a torus is released through several channels. We have determined that a minor fraction of the energy is released in baryon-poor outflows from a differentially rotating open magnetic flux tube, and a major fraction of about eta/2 is released in gravitational radiation by the torus with angular velocity eta similar 0.2 to 0.5 relative to that of the black hole. We associate the energy emitted in baryon-poor outflows with gamma-ray bursts. The remaining fraction is released in torus winds, thermal emissions, and (conceivably) megaelectron-volt neutrino emissions. The emitted gravitational radiation can be detected by gravitational wave experiments and provides a method for identifying Kerr black holes in the Universe. PMID:11859153

van Putten, Maurice H P M; Levinson, Amir

2002-02-21

336

Increment Thresholds on Black Bars.  

National Technical Information Service (NTIS)

Under conditions that isolate rod vision, increment thresholds were measured on black bars of various widths, and compared to the increment threshold measured on a homogeneously illuminated field without the bar. Thresholds were found to be elevated in th...

D. Y. Teller

1968-01-01

337

Threshold photoelectrons coincidence spectroscopy of doubly charged ions of hydrogen chloride and chlorine  

Microsoft Academic Search

Single photon double ionization of hydrogen chloride (HCl) and chlorine (Cl2) has been studied in an electron-electron coincidence experiment. Threshold PhotoElectrons COincidence (TPEsCO) spectra have been obtained by using a penetrating field technique, in which only electrons with nearly zero kinetic energy (<20 meV) are detected. The high sensitivity and energy resolution attainable has allowed observation of several states of

A. G. McConkey; G. Dawber; L. Avaldi; M. A. MacDonald; G. C. King; R. I. Hall

1994-01-01

338

Positron-Electron Pair Creation Near Threshold  

SciTech Connect

Positron-electron pair creation near the threshold energy is extremely difficult to investigate by both experiments and theory. First test experiments were performed at the ILL to determine the cross sections for positron-electron pair creation near threshold using prompt {gamma}-rays from different targets after neutron capture and conventional radioactive sources. Pair creation was studied in a Ge detector, which simultaneously acted as sample and detector. First results are presented which show a significant deviation from theoretical values near threshold.

Frahm, Ronald; Luetzenkirchen-Hecht, Dirk [Fachgruppe Physik, Bergische Universitaet Wuppertal, Gaussstr. 20, 42097 Wuppertal (Germany); Jentschel, Michael; Urban, Waldemar; Krempel, Jochen [Institut Laue-Langevin, 6 rue Jules Horowitz, 38000 Grenoble (France); Schreckenbach, Klaus [Physik-Department E21, Technische Univ. Muenchen, James-Franck-Str., 85748 Garching (Germany)

2009-01-28

339

A novel threshold Cherenkov detector  

NASA Astrophysics Data System (ADS)

We are studying a novel threshold Cherenkov detector system for the discrimination between charged pions and kaons in an experiment on CP breaking at LEAR, CERN. Cherenkov UV-light is produced in an FC72 radiator and detected in a row of 2 cm diameter quartz tubes filled with TMAE vapour at 45°C. Inside a tube a wire is stretched along the axis as anode and a nichrome spiral functions as cathode. Computer simulations have shown that good pion/kaon discrimination can be obtained. First results obtained with a small quartz-tube light detector are presented.

Okx, W. J. C.; van Eijk, C. W. E.; Looman, M.; Tanner, N. W.

1988-12-01

340

Unimolecular isomerization of CH2FCD2Cl via the interchange of Cl and F atoms: assignment of the threshold energy to the 1,2-dyotropic rearrangement.  

PubMed

The room-temperature gas-phase recombination of CH2F and CD2Cl radicals was used to prepare CH2FCD2Cl molecules with 91 kcal mol(-1) of vibrational energy. Three unimolecular processes are in competition with collisional deactivation of CH2FCD2Cl; HCl and DF elimination to give CHF?CD2 and CH2?CDCl plus isomerization to give CH2ClCD2F by the interchange of F and Cl atoms. The Cl/F interchange reaction was observed, and the rate constant was assigned from measurement of CHCl?CD2 as a product, which is formed by HF elimination from CH2ClCD2F. These experiments plus previously published results from chemically activated CH2ClCH2F and electronic structure and RRKM calculations for the kinetic-isotope effects permit assignment of the three rate constants for CH2FCD2Cl (and for CH2ClCD2F). The product branching ratio for the interchange reaction versus elimination is 0.24 ± 0.04. Comparison of the experimental rate constant with the RRKM calculated rate constant permitted the assignment of a threshold energy of 62 ± 3 kcal mol(-1) for this type-1 dyotropic rearrangement. On the basis of electronic structure calculations, the nature of the transition state for the rearrangement reaction is discussed. The radical recombination reactions in the chemical system also generate vibrationally excited CD2ClCD2Cl and CH2FCH2F molecules, and the rate constants for DCl and HF elimination were measured in order to confirm that the photolysis of CD2ClI and (CH2F)2CO mixtures was giving reliable data for CH2FCD2Cl. PMID:23837645

Tucker, Mary K; Rossabi, Samuel M; McClintock, Corey E; Heard, George L; Setser, D W; Holmes, Bert E

2013-07-26

341

Amplitude modulation thresholds for the parakeet ( Melopsittacus undulatus )  

Microsoft Academic Search

Parakeets were tested for the ability to detect sinusoidal amplitude modulation of broad band noise. Instrumental avoidance conditioning and a psychophysical modified method of limits procedure were used to measure the threshold for detecting amplitude modulation at 10 modulation frequencies between 2 and 2,048 Hz. Below about 40 Hz, modulation threshold is independent of modulation rate and noise level. Above

Robert J. Dooling; Margaret H. Searcy

1981-01-01

342

Radar Detection of ultra high energy cosmic rays  

NASA Astrophysics Data System (ADS)

We revisit the radar echo technique as an approach to detect ultra high energy cosmic rays (UHECR). The UHECR extensive air showers produce disk-like ionization fronts propagating with a relativistic speed and creating fast decaying plasma. We study the reflection of a radio wave, such as the one from a radar transmitter or commercial radio and TV station, from the ionization front. The reflected wave will be frequency up-shifted due to relativistic Doppler effect. The amplitude of the reflected wave depends strongly on velocity of the front, and density and collision frequency of the plasma behind it. The returned power will be shown for typical extensive air shower parameters. )

Kryemadhi, Abaz; Bakunov, Michael; Maslov, Alex; Novokovskaya, Alina

2010-02-01

343

Near threshold fatigue testing  

NASA Astrophysics Data System (ADS)

Measurement of the near-threshold fatigue crack growth rate (FCGR) behavior provides a basis for the design and evaluation of components subjected to high cycle fatigue. Typically, the near-threshold fatigue regime describes crack growth rates below approximately 10(exp -5) mm/cycle (4 x 10(exp -7) inch/cycle). One such evaluation was recently performed for the binary alloy U-6Nb. The procedures developed for this evaluation are described in detail to provide a general test method for near-threshold FCGR testing. In particular, techniques for high-resolution measurements of crack length performed in-situ through a direct current, potential drop (DCPD) apparatus, and a method which eliminates crack closure effects through the use of loading cycles with constant maximum stress intensity are described.

Freeman, D. C.; Strum, M. J.

1993-01-01

344

Detecting special nuclear materials in containers using high-energy gamma rays emitted by fission products  

DOEpatents

A method and a system for detecting the presence of special nuclear materials in a container. The system and its method include irradiating the container with an energetic beam, so as to induce a fission in the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

Norman, Eric B. (Oakland, CA); Prussin, Stanley G. (Kensington, CA)

2007-10-02

345

Definition of thresholds for stereoscopic depth.  

PubMed Central

In the laboratory, thresholds for stereoscopic depth perception are usually determined by asking observers to discriminate between a stimulus with a given depth offset and its mirror image. Threshold is most often defined as the disparity difference that yields 75% or 83% correct responses. Disparities used for clinical tests of stereopsis are much higher. Here it is argued that, among other factors, this is because of the fact that clinical tests usually require the detection of a depth difference (offset versus no offset), rather than the discrimination between two directions of depth difference (in front versus behind). From a formal comparison of the two tasks, the data show that discrimination, or classification is easier by at least a factor of 2 than detection. The contribution of variations of the threshold criterion and learning to the differences between stereoacuity as measured in laboratory and clinic is also discussed. These differences are relevant to the design of tests for clinical use.

Fahle, M; Henke-Fahle, S; Harris, J

1994-01-01

346

High energy muon number spectrum detected at the Baksan Underground Scintillation Telescope  

Microsoft Academic Search

Integral muon number spectrum has been measured at the Baksan Underground Scintillation Telescope (BUST) for near vertical directions (theta<=20°, effective muon threshold energy is 230 GeV). The analyzed range of the number of muon tracks crossing BUST is 2 170. It corresponds to the primary energy range 3s10 eV 10 eV. Muon number spectrum calculations have been carried out for

V. B. Petkov; J. Szabelski; D. V. Smirnov; R. V. Novoseltseva

2008-01-01

347

Setting Graduation Rate Thresholds.  

ERIC Educational Resources Information Center

Reviews the college completion/graduation rate thresholds developed by several states and discusses advantages and disadvantages of several statistical approaches, including use of the one standard deviation lower bound method, the logit prediction bound method, the linear regression method, and the logistic regression method. (DB)

Underwood, David G.; Rieck, James R.

1999-01-01

348

Robust Threshold DSS Signatures  

Microsoft Academic Search

We present threshold DSS (Digital Signature Standard) signatures where the power to sign is shared by players such that for a given parameter any subset of signers can collaborate to produce a valid DSS signature on any given message, but no subset of corrupted players can forge a signature (in particular, cannot learn the signature key). In addition, we present

Rosario Gennaro; Stanislaw Jarecki; Hugo Krawczyk; Tal Rabin

1996-01-01

349

Practical Threshold Signatures  

Microsoft Academic Search

We present an RSA threshold signature scheme. The scheme enjoys the following properties: 1. it is unforgeable and robust in the random oracle model, assuming the RSA problem is hard; 2. signature share generation and veriflcation is completely non-inter- active; 3. the size of an individual signature share is bounded by a constant times the size of the RSA modulus.

Victor Shoup

2000-01-01

350

Optical model calculations on the threshold anomaly for the {sup 6}Li+{sup 28}Si and {sup 7}Li+{sup 28}Si systems at near-Coulomb-barrier energies  

SciTech Connect

A simultaneous analysis of elastic scattering, fusion, and total reaction cross sections for the weakly bound systems {sup 6,7}Li+{sup 28}Si at energies close to the Coulomb barrier is performed by optical model calculations. The nuclear polarization potential U is split into volume part U{sub F}, which accounts for fusion reactions and a surface part U{sub DR}, responsible for direct reactions. The parameters of the Woods-Saxon potentials are determined by a {chi}{sup 2} analysis of the data. The presence of the threshold anomaly or the breakup threshold anomaly is investigated from the energy dependence of both the fusion and direct reaction parts of the polarization potential.

Gomez Camacho, A. [Departamento de Aceleradores, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, C.P. 11801, Mexico, D.F. (Mexico); Gomes, P. R. S.; Lubian, J. [Instituto de Fisica, Universidade Federal Fluminenese, Avenida Litoranea s/n, Gragoata, Niteroi, Rio de Janeiro 24210-340 (Brazil)

2010-12-15

351

Selective chemical detection by energy modulation of sensors  

DOEpatents

A portable instrument for use in the field in detecting, identifying, and quantifying a component of a sampled fluid includes a sensor which chemically reacts with the component of interest or a derivative thereof, an electrical heating filament for heating the sample before it is applied to the sensor, and modulator for continuously varying the temperature of the filament (and hence the reaction rate) between two values sufficient to produce the chemical reaction. In response to this thermal modulation, the sensor produces a modulated output signal, the modulation of which is a function of the activation energy of the chemical reaction, which activation energy is specific to the particular component of interest and its concentration. Microprocessor which compares the modulated output signal with standard responses for a plurality of components to identify and quantify the particular component of interest. In particular, the concentration of the component of interest is proportional to the amplitude of the modulated output signal, while the identifying activation output energy of the chemical interaction indicative of that component is proportional to a normalized parameter equal to the peak-to-peak amplitude divided by the height of the upper peaks above a base line signal level. 5 figures.

Stetter, J.R.; Otagawa, T.

1991-09-10

352

Near-threshold ionization by positron impact  

NASA Astrophysics Data System (ADS)

Interest in near-threshold ionization is discussed and an experiment is described aimed at its measurement by positron impact. The method involves an ion time-of-flight system triggered by the detection of the scattered projectiles. This latter task will be assisted by a weak electric field penetrating the interaction region.

Ashley, P.; Laricchia, G.; Charlton, M.

1994-12-01

353

A low threshold EAS (extensive-air-shower) array for gamma-ray astronomy at Los Alamos  

SciTech Connect

A new type of extensive-air-shower (EAS) array is described that achieves a low energy threshold, large area, high duty factor and large muon coverage. By placing a regularly-spaced grid of phototubes just below the surface of a shallow pond, the Cherenkov light of particles in an air shower striking the water can be detected, resulting in a primary energy threshold of less than 1 TeV. This highly sensitive array can thus be used to span the gap of information between the existing air Cherenkov techniques at 1 TeV and the existing EAS arrays at 100 TeV. 5 refs., 3 figs.

Burman, R.L.; Hoffman, C.M.; Nagle, D.E.; Potter, M.E.; Sandberg, V.; Berley, D.; Dingus, B.L.; Goodman, J.A.; Haines, T.J.; Stark, M.; Ellsworth, R.W.; Alexandreas, D.E.; Biller, S.; Dion, G.; Lu, X.Q.; Vishwanath, P.R.; Yodh, G.B.; Tumer, T.; White, S.; Zych, A.; Freedman, S.; Krakauer, D.; Lamb, R. (Los Alamos National Lab., NM (USA); Maryland Univ., College Park, MD (USA); George Mason Univ., Fairfax, VA (USA); Ca

1990-01-01

354

Supply and threshold voltage scaling for low power CMOS  

Microsoft Academic Search

This paper investigates the effect of lowering the supply and threshold voltages on the energy efficiency of CMOS circuits. Using a first-order model of the energy and delay of a CMOS circuit, we show that lowering the supply and threshold voltage is generally advantageous, especially when the transistors are velocity saturated and the nodes have a high activity factor, In

Ricardo Gonzalez; Benjamin M. Gordon; Mark A. Horowitz

1997-01-01

355

Quantifying ecological thresholds in a complex world  

NASA Astrophysics Data System (ADS)

Ecological thresholds are abrupt changes of ecological state. Most empirical methods detect ecological thresholds in time or across geographic space. Although useful, these approaches do not quantify the direct drivers of a threshold response. Causal understanding of thresholds detected empirically requires their investigation in a domain containing the direct drivers (often referred to as state space). Currently, no method quantifies thresholds with respect to more than one driver in state space. Here, we present an approach designed to better accomodate complexity; the approach quantifies thresholds in state space with more than one driver. We present two indices of shape attributes measured from 3-D response surfaces, threshold strength (T) and diagonality (D). We use 48 simulated response surfaces of different shapes to test the efficacy of the indices. T is sensitive to the steepness of the transition from one state to the next, with various forms of abrupt, centralized thresholds yielding the highest values among the simulated surfaces. D represents the orientation of the response surface in state space or the simultaneous influence of more than one predictor in eliciting the response. Strongly diagonal surfaces have the most diagonal surface area demonstrated by sharply undulating diagonal surfaces. Given that the success of T and D requires a regression method to accurately capture any shape of complex data structure as a response surface, we also test the accuracy of regression methods known to be tractable with complex data. We test Classification and Regression Trees (CART), Random Forest, and Non-Parametric Multiplicative Regression (NPMR) for binary and continuous responses. We use the 48 simulated response surfaces to test the methods, and we find that prediction accuracy depends on both the T and D of the simulated data for each method. We choose the most accurate method among those we test for capturing any shape of response surface from real data, NPMR. Finally, we use NPMR to build response surfaces from which we quantify T and D for real ecological data sets. We demonstrate how measurement of threshold strength and diagonality from multi-factor response surfaces can advance our understanding of thresholds using several examples: tree mortality from bark beetles, woody plant vulnerability curves, and species probability of occurrence with respect to climate.

Lintz, H. E.; McCune, B.; Gray, A. N.; McCulloh, K. A.

2010-12-01

356

Snapshot molecular imaging using coded energy-sensitive detection.  

PubMed

We demonstrate a technique for measuring the range-resolved coherent scatter form factors of different objects from a single snapshot. By illuminating the object with an x-ray pencil beam and placing a coded aperture in front of a linear array of energy-sensitive detector elements, we record the coherently scattered x-rays. This approach yields lateral, range, and momentum transfer resolutions of 1 mm, 5 mm, and 0.2 nm-1, respectively, which is sufficient for the distinguishing a variety of solids and liquids. These results indicate a path toward real-time volumetric molecular imaging for non-destructive examination in a variety of applications, including medical diagnostics, quality inspection, and security detection. PMID:24150387

Greenberg, Joel A; Krishnamurthy, Kalyani; Brady, David

2013-10-21

357

Dynamical thresholds for complete fusion  

SciTech Connect

It is our purpose here to study the effect of nuclear dissipation and shape parametrization on dynamical thresholds for compound-nucleus formation in symmetric heavy-ion reactions. This is done by solving numerically classical equations of motion for head-on collisions to determine whether the dynamical trajectory in a multidimensional deformation space passes inside the fission saddle point and forms a compound nucleus, or whether it passes outside the fission saddle point and reseparates in a fast-fission or deep-inelastic reaction. Specifying the nuclear shape in terms of smoothly joined portions of three quadratic surfaces of revolution, we take into account three symmetric deformation coordinates. However, in some cases we reduce the number of coordinates to two by requiring the ends of the fusing system to be spherical in shape. The nuclear potential energy of deformation is determined in terms of a Coulomb energy and a double volume energy of a Yukawa-plus-exponential folding function. The collective kinetic energy is calculated for incompressible, nearly irrotational flow by means of the Werner-Wheeler approximation. Four possibilities are studied for the transfer of collective kinetic energy into internal single-particle excitation energy: zero dissipation, ordinary two body viscosity, one-body wall-formula dissipation, and one-body wall-and-window dissipation. (WHK)

Davies, K.T.R.; Sierk, A.J.; Nix, J.R.

1983-01-01

358

The reactor noise threshold  

Microsoft Academic Search

Time-domain noise analysis techniques such as the Rossi-[alpha], the variance-to-mean, and the interval-distribution methods can be used to measure fundamental reactor parameters in a wise variety of reactor systems, provided the power level of the system is not too high. Simple expressions have been derived that define the maximum power level (i.e., the reactor noise threshold) above which time-domain reactor

Spriggs

1994-01-01

359

Some photoneutron thresholds  

Microsoft Academic Search

The photeneutron thresholds for a number of elements which have 100% ; abundance (or nearly so) in one stable isotope have been measured. The following ; values in Mev were found: Na (12.47 plus or minus 0.05), Al (12.98 plus or ; minus 0.08), P (12.50 plus or minus 0.05), V (11.16 plus or minus 0.05), Mn ; (10.14 plus

B. G. Chidley; L. Katz; S. L. f Kowalski

1958-01-01

360

Threshold Entrusted Undeniable Signature  

Microsoft Academic Search

\\u000a Entrusted undeniable signatures are like undeniable signatures, except that the disavowal protocol can only be run by a court\\u000a in order to resolve a formal dispute. This paper introduces threshold entrusted undeniable signature scheme without trusted\\u000a center. It is shown how the power to run a disavowal protocol of entrusted undeniable signature can be distributed to n agents such that

Seungjoo Kim; Dongho Won

2004-01-01

361

Vision thresholds revisited  

NASA Astrophysics Data System (ADS)

During and just after World War II there was intense interest in the threshold for seeing faint sources against illuminated backgrounds. Knoll, Tousey and Hulburt (1946, 1948) determined the threshold for (effectively) point sources seen against backgrounds ranging in brightness from darkness to subdued daylight. Blackwell (1946) gave contrast ratios for sources of various sizes ranging from point sources up to circular disks of 6 degrees diameter, all seen against the same range of brightnesses, and determined by a very large number of visual observations made by a team of observers. I have combined the two sets of results, and represented them by an improvement on the theoretical formula for threshold illuminance as a function of background brightness which was suggested by Hecht (1934). My formula agrees very well with the observations, and is very suitable for incorporation into computer programs. Applications have been made to problems where the background brightness is caused by light pollution, and the source size is determined by the seeing. These include the optimum magnification and limiting magnitude of telescopes, and the analysis of visual limiting magnitudes determined by Bowen (1947) to determine the night sky brightness at Mount Wilson in 1947.

Garstang, R. H.

1999-05-01

362

Threshold Concepts in Research Education and Evidence of Threshold Crossing  

ERIC Educational Resources Information Center

Most work on threshold concepts has hitherto related to discipline-specific undergraduate education, however, the idea of generic doctoral-level threshold concepts appeared to us to provide a strong and useful framework to support research learning and teaching at the graduate level. The early work regarding research-level threshold concepts is…

Kiley, Margaret; Wisker, Gina

2009-01-01

363

A dual threshold calculating method for fiber's edge extraction  

Microsoft Academic Search

In the fiber cross-sectional image analysis system, correctly detecting fiber's edge is critical for fiber geometric feature extraction and further fiber identification. In this paper, a dual threshold calculating method is proposed to obtain accurate and continuous fiber edge, as well as to control the image noise. After eliminating the non-uniform illumination in the fiber image, the low threshold is

Yan Wan; Li Yao; Bugao Xu

2009-01-01

364

The role of Cherenkov radiation in the detection of ultra-high-energy cosmic rays  

NASA Astrophysics Data System (ADS)

A brief historical overview of the role of Cherenkov radiation in the detection of cosmic rays is given. A current application, the detection of ultra-high-energy cosmic rays with the Pierre Auger Observatory, is described.

Watson, A. A.

2005-11-01

365

Sample Splitting and Threshold Estimation  

Microsoft Academic Search

Threshold models have a wide variety of applications in economics. Direct applications include models of separating and multiple equilibria. Other applications include empirical sample splitting when the sample split is based on a continuously-distributed variable such as firm size. In addition, threshold models may be used as a parsimonious strategy for nonparametric function estimation. For example, the threshold autoregressive model

Bruce E. Hansen

2000-01-01

366

Speech Denoising by SoftSoft Thresholding  

Microsoft Academic Search

Many noise-reduction methods are based on the possibility of representing the clean signal with a reduced number of transform coefficients, so that cancelling coefficients below a certain thresholding level produces an enhanced reconstructed signal. It is assumed that the clean signal has a sparse representation, while noise energy is spread over all coefficients. The main drawback of those methods is

Irineu Antunes Jr; P. M. S. Burt

2006-01-01

367

The reactor noise threshold  

SciTech Connect

Time-domain noise analysis techniques such as the Rossi-[alpha], the variance-to-mean, and the interval-distribution methods can be used to measure fundamental reactor parameters in a wise variety of reactor systems, provided the power level of the system is not too high. Simple expressions have been derived that define the maximum power level (i.e., the reactor noise threshold) above which time-domain reactor noise techniques are likely to fail in subcritical, critical, and supercritical systems.

Spriggs, G.D. (Los Alamos National Lab., NM (United States))

1994-01-01

368

''Magic'' Energies for Detecting Light Elements with Resonant Alpha Particle Backscattering  

SciTech Connect

Resonant backscattering is widely used to improve the detection limit of the light elements such as B, C, N and O. One disadvantage, however, is that several incident energies are normally needed if the sample contains a number of the light elements. There are ''magic'' energies at which several light elements can be detected simultaneously with suitable sensitivities. When these energies are used along with the elastic recoil detection of hydrogen, multiple elements can be detected without changing the beam energy, and the analysis time is greatly reduced. These reactions along with examples will be discussed.

Wetteland, C.J.; Maggiore, C.J.; Tesmer, J.R.; He, X-M.; Lee, D-H.

1998-11-04

369

Coloring geographical threshold graphs  

SciTech Connect

We propose a coloring algorithm for sparse random graphs generated by the geographical threshold graph (GTG) model, a generalization of random geometric graphs (RGG). In a GTG, nodes are distributed in a Euclidean space, and edges are assigned according to a threshold function involving the distance between nodes as well as randomly chosen node weights. The motivation for analyzing this model is that many real networks (e.g., wireless networks, the Internet, etc.) need to be studied by using a 'richer' stochastic model (which in this case includes both a distance between nodes and weights on the nodes). Here, we analyze the GTG coloring algorithm together with the graph's clique number, showing formally that in spite of the differences in structure between GTG and RGG, the asymptotic behavior of the chromatic number is identical: {chi}1n 1n n / 1n n (1 + {omicron}(1)). Finally, we consider the leading corrections to this expression, again using the coloring algorithm and clique number to provide bounds on the chromatic number. We show that the gap between the lower and upper bound is within C 1n n / (1n 1n n){sup 2}, and specify the constant C.

Bradonjic, Milan [Los Alamos National Laboratory; Percus, Allon [Los Alamos National Laboratory; Muller, Tobias [EINDHOVEN UNIV. OF TECH

2008-01-01

370

Development of a Manual Threshold Immunoassay for Bacillus anthracis Spores.  

National Technical Information Service (NTIS)

An immunoassay applicable to the Manual Threshold instrument was developed for the detection of Bacillus anthracis spores. The assay involved two antibodies raised against inactivated spores of B. anthracis Sterne strain 34F2, and they were labelled with ...

C. Liu C. Browning

2005-01-01

371

Utilization of high-energy neutrons for the detection of fissionable materials  

SciTech Connect

The detection of high-energy prompt fission neutrons was investigated as a method of fissionable material detection. Neutron energy spectra of {sup 238}U and several nonfissionable materials were measured using a neutron time of flight spectrometer. The photonuclear reactions were induced in the targets using a pulsed bremsstrahlung beam for several endpoint energies between 8 and 15 MeV. While fission neutrons can have energies in excess of 10 MeV, neutrons emitted from nonfissionable materials have distinct energy limits that depend upon binding and incident particle energies. Hence the presence of high-energy neutrons can be used to discriminate fissionable from most nonfissionable materials.

Thompson, S. J.; Kinlaw, M. T.; Harmon, J. F.; Wells, D. P.; Farfan, E. B.; Hunt, A. W. [Idaho Accelerator Center, Idaho State University, Pocatello, Idaho 83209-8263 and Department of Physics, Idaho State University, Pocatello, Idaho 83209-8106 (United States)

2007-02-12

372

Wideband ipsilateral measurements of middle-ear muscle reflex thresholds in children and adultsa  

PubMed Central

The goals of the current study were to: 1) evaluate the feasibility of a new wideband approach to measuring middle-ear muscle reflex (MEMR) status, and 2) to test the hypothesis that ipsilateral thresholds elicited with 1 or 2 kHz tones and broadband noise activators on a wideband acoustic transfer function (WATF) system are lower than thresholds elicited on a clinical system. Clinical MEMR tests have limitations, including the need for high activator levels to elicit a shift in a narrowband probe (e.g., a 0.226 or 1 kHz tone). Wideband MEMR tests using WATFs may elicit the reflex at lower levels because a wideband probe (click) is used and the threshold detection criterion can be wideband. Mean wideband MEMR thresholds across 40 normal-hearing adult ears were 2.2–4.0 dB lower than clinical MEMR thresholds, depending on the activator and specific WATF test used (admittance magnitude or energy reflectance). Wideband MEMR has potential clinical utility beyond the adult population, including use in newborn and preschool hearing screenings. In a newborn hearing screening, for example, wideband MEMR could be completed with the same system as otoacoustic emissions. However, further investigations in infants and young children are needed.

Schairer, Kim S.; Ellison, John C.; Fitzpatrick, Denis; Keefe, Douglas H.

2007-01-01

373

A Zero-Degree Spectrometer in CELSIUS and the d(d,2?)4He Reaction Close to Threshold  

NASA Astrophysics Data System (ADS)

In near-threshold reactions the heavy reaction products are emitted within a narrow cone in the forward direction. To detect these a small-size charged-particle telescope has been built that is operated inside the vacuum chamber within the dipole magnets of the CELSIUS storage ring. The first aim has been to study two-pion production close to threshold. By measuring the d(d,2')4He reaction at a beam energy of 569 MeV, corresponding to 29 MeV above the production threshold for two neutral pions in the c.m., we add a low-energy and point to the previous experiments concerning this reaction. The two pions are produced in a T=0 channel which is the signature of the so called ABC-effect.

Bargholtz, Chr.; Fransson, K.; Holmberg, L.; Lindh, K.; Sandberg, L.; Proti?, D.; Sitnikova, I.; Tegnér, P.-E.; Engblom, P. Thörngren; Weiss, G.; Rolander, K. Wilhelmsen

1997-02-01

374

Threshold photoelectron source for the study of low-energy electron scattering: Total cross section for electron scattering from krypton in the energy range from 14 meV to 20 eV  

SciTech Connect

An experimental technique for the measurement of the total cross section for electron scattering from atoms and molecules at high resolution is described. The total cross sections for electron scattering from Kr in the energy range from 14 meV to 20 eV obtained with the technique are also reported. The present technique employs a combination of the penetrating field technique and the threshold photoionization of rare-gas atoms using synchrotron radiation as an electron source in order to produce a high-resolution electron beam at very low energy. The characteristics of the electron sources were determined by measuring the ionizing photon energy dependence of photoelectron yield. Absolute total cross sections for electron scattering are obtained by the attenuation method. The measured absolute values of the total cross sections for electron scattering from Kr agree with those obtained by other groups down to 175 meV, above which several experimental works have been reported. Below 175 meV, the present results generally agree with theoretical cross sections down to 14 meV. The resonant structures in the total cross sections due to Kr{sup -} (4p{sup 5}5s{sup 2} {sup 2}P{sub 3/2}) and the Kr{sup -} (4p{sup 5}5s{sup 2} {sup 2}P{sub 1/2}) Feshbach resonances are also reported. The resolution of the present setup has been estimated from a fit of the measured profile of the Kr{sup -} (4p{sup 5}5s{sup 2} {sup 2}P{sub 3/2}) resonance by the theoretical curve obtained from the resonant scattering theory.

Kurokawa, M.; Kitajima, M.; Toyoshima, K.; Odagiri, T. [Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Kato, H.; Kawahara, H.; Hoshino, M.; Tanaka, H. [Department of Physics, Sophia University, Tokyo 102-8554 (Japan); Ito, K. [Photon Factory, Institute of Materials Structure Science, Tsukuba 305-0801 (Japan)

2010-12-15

375

Oscillatory threshold logic.  

PubMed

In the 1940s, the first generation of modern computers used vacuum tube oscillators as their principle components, however, with the development of the transistor, such oscillator based computers quickly became obsolete. As the demand for faster and lower power computers continues, transistors are themselves approaching their theoretical limit and emerging technologies must eventually supersede them. With the development of optical oscillators and Josephson junction technology, we are again presented with the possibility of using oscillators as the basic components of computers, and it is possible that the next generation of computers will be composed almost entirely of oscillatory devices. Here, we demonstrate how coupled threshold oscillators may be used to perform binary logic in a manner entirely consistent with modern computer architectures. We describe a variety of computational circuitry and demonstrate working oscillator models of both computation and memory. PMID:23173034

Borresen, Jon; Lynch, Stephen

2012-11-16

376

Two-Source Double-Slit Interference in Angle-Resolved High-Energy Above-Threshold Ionization Spectra of Diatoms  

SciTech Connect

When an electron from a diatomic molecule undergoes tunneling-rescattering ionization, a novel form of destructive interference can be realized that involves all four geometric orbits that are available to the electron when it is freed, because both ionization and rescattering may take place at the same or at different centers. We find experimentally and confirm theoretically that in orientation-averaged angle-resolved high-order above-threshold ionization spectra the corresponding destructive interference is visible for O{sub 2} but not for N{sub 2}. This effect is different from the suppression of ionization that is well known to occur for O{sub 2}.

Okunishi, M.; Itaya, R.; Shimada, K.; Pruemper, G.; Ueda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Busuladzic, M. [Medical Faculty, Cekalusa 90, University of Sarajevo, 71000 Sarajevo (Bosnia and Herzegowina); Gazibegovic-Busuladzic, A. [Faculty of Science, Zmaja od Bosne 35, University of Sarajevo, 71000 Sarajevo (Bosnia and Herzegowina); Milosevic, D. B. [Faculty of Science, Zmaja od Bosne 35, University of Sarajevo, 71000 Sarajevo (Bosnia and Herzegowina); Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin (Germany); Becker, W. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin (Germany)

2009-07-24

377

Earnings Management to Exceed Thresholds  

Microsoft Academic Search

Earnings provide important information for investment decisions. Thus, executives--who are monitored by investors, directors, customers, and suppliers--acting in self-interest and at times for shareholders, have strong incentives to manage earnings. The authors introduce behavioral thresholds for earnings management. A model shows how thresholds induce specific types of earnings management. Empirical explorations identify earnings management to exceed each of three thresholds:

Francois Degeorge; Jayendu Patel; Richard Zeckhauser

1999-01-01

378

DEVELOPMENT OF A FAULT DETECTION SYSTEM FOR WIND ENERGY CONVERTERS  

Microsoft Academic Search

Unforeseen failure of components of a wind turbine can have a significant impact on the turbine economy. A promising approach to avoid such failures is the concept of on-line fault detection. By continuous supervision of the dynamic behaviour of a WEC incipient faults can be detected at a very early stage. Thus, secondary defects and major breakdowns can be avoided.

P. Caselitz; J. Giebhardt; T. Krüger; M. Mevenkamp

379

An adaptive detection model of moving dim targets based on energy difference between frames  

NASA Astrophysics Data System (ADS)

The paper is based on biology vision stared mechanism, applies the detective arithmetic operators of static image into the system of moving dim targets detection ,brings forward an adaptive detective model of moving dim targets based on energy difference between frames, and optimizes and selects the parameters in the mathematic model. Experiments completed by the paper proving, the adaptive detective model can detect moving dim targets real-timely and exactly. Detection and tracking of moving dim targets are the most important part of the system of watching and alarming. So it's essential to find and detect the targets in time. Because of claim of detecting targets at long bowls, the targets usually are regarded as the dot targets or pixels in the system of watching and alarming. So detection of infrared dim targets is one of key technology in the weapon system, and one important project in moving targets detection. We aim at slowing down signal-to-noise ratio in the detection of moving dim targets by the way of classical frame difference and rapid matching, bring out a new anisotropic moving detection model between frames in the study of theories of biology vision fixated mechanism, and analyze and research on selection of more parameters in the detection model. Experimental results show that the algorithm based on energy difference comparing between frames which is brought out by this paper is effective and practical to detect moving dim small targets.

Liu, Yuanyuan; Yan, Guoping

2009-12-01

380

Measuring the speed of dark: Detecting dark energy perturbations  

SciTech Connect

The nature of dark energy can be probed not only through its equation of state but also through its microphysics, characterized by the sound speed of perturbations to the dark energy density and pressure. As the sound speed drops below the speed of light, dark energy inhomogeneities increase, affecting both cosmic microwave background and matter power spectra. We show that current data can put no significant constraints on the value of the sound speed when dark energy is purely a recent phenomenon, but can begin to show more interesting results for early dark energy models. For example, the best fit model for current data has a slight preference for dynamics [w(a){ne}-1], degrees of freedom distinct from quintessence (c{sub s{ne}}1), and early presence of dark energy [{Omega}{sub de}(a<<1){ne}0]. Future data may open a new window on dark energy by measuring its spatial as well as time variation.

Putter, Roland de [Berkeley Lab and University of California, Berkeley, California 94720 (United States); Huterer, Dragan [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan, 48109 (United States); Linder, Eric V. [Berkeley Lab and University of California, Berkeley, California 94720 (United States); Institute for the Early Universe, Ewha Womans University, Seoul (Korea, Republic of)

2010-05-15

381

Probabilistic Threshold Criterion  

SciTech Connect

The Probabilistic Shock Threshold Criterion (PSTC) Project at LLNL develops phenomenological criteria for estimating safety or performance margin on high explosive (HE) initiation in the shock initiation regime, creating tools for safety assessment and design of initiation systems and HE trains in general. Until recently, there has been little foundation for probabilistic assessment of HE initiation scenarios. This work attempts to use probabilistic information that is available from both historic and ongoing tests to develop a basis for such assessment. Current PSTC approaches start with the functional form of the James Initiation Criterion as a backbone, and generalize to include varying areas of initiation and provide a probabilistic response based on test data for 1.8 g/cc (Ultrafine) 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and LX-17 (92.5% TATB, 7.5% Kel-F 800 binder). Application of the PSTC methodology is presented investigating the safety and performance of a flying plate detonator and the margin of an Ultrafine TATB booster initiating LX-17.

Gresshoff, M; Hrousis, C A

2010-03-09

382

Sulfur K{beta} x-ray emission from carbonyl sulfide: Variations with polarization and excitation energy at the S K threshold  

SciTech Connect

Sulfur K{beta} x-ray-emission spectra from carbonyl sulfide have been measured with resonant excitation at the sulfur K absorption threshold and compared with results of self-consistent field and singles-doubles configuration-interaction calculations. For excitation to the strong 4{pi} absorption resonance, a splitting of the main emission peak is interpreted in terms of influence of the 4{pi} electron on the final valence-hole states. The polarization selectivity of the emission spectrometer was used to distinguish emission polarized parallel versus perpendicular with respect to the polarization of the excitation radiation. The observed polarization dependence is consistent with the molecular symmetries of the calculated intermediate and final states. {copyright} {ital 1998} {ital The American Physical Society}

Miyano, K.E. [Department of Physics, Brooklyn College, Brooklyn, New York 11210 (United States); Arp, U. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Southworth, S.H. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Meehan, T.E.; Walsh, T.R.; Larkins, F.P. [School of Chemistry, The University of Melbourne, Parkville, (Australia) 3052

1998-04-01

383

Cadmium zinc telluride (CZT) nanowire sensors for detection of low energy gamma-ray detection  

Microsoft Academic Search

Bulk single crystals of CdZnTe compound semiconductor is used for room temperature radiation detection in commercial radiation sensors. A large volume of detector material with low defect density is required for increasing the detection efficiency. Manufacture of such a bulky detector-quality material with low defect density is expensive. In this communication, synthesis of nanowires arrays of CdZnTe that can be

T. Gandhi; K. S. Raja; M. Misra

2008-01-01

384

Generation and detection of high-energy phonons by superconducting junctions  

Microsoft Academic Search

It is demonstrated that phonons with energy greater than the superconducting gap escape Sn junction generators in sufficient number to be detected by Pb superconducting junctions. The phonon transconductance signal, observed with high generator bias, can be largely understood in terms of the relaxation of injected quasiparticles which emit high-energy phonons. The high-energy phonons are in turn reabsorbed to form

I. L. Singer; W. E. Bron

1976-01-01

385

Generation and detection of high-energy phonons by superconducting junctions  

Microsoft Academic Search

It is demonstrated that phonons, with energy greater than the superconducting gap, escape Sn junction generators in sufficient number to be detected by Pb superconducting junctions. The phonon transconductance signal, observed with high generator bias, can be largely understood in terms of the relaxation of injected quasiparticles which emit high-energy phonons. The high-energy phonons are in turn reabsorbed to form

I. L. Singer; W. E. Bron

1976-01-01

386

Threshold Concepts and Information Literacy  

ERIC Educational Resources Information Center

|What do we teach when we teach information literacy in higher education? This paper describes a pedagogical approach to information literacy that helps instructors focus content around transformative learning thresholds. The threshold concept framework holds promise for librarians because it grounds the instructor in the big ideas and underlying…

Townsend, Lori; Brunetti, Korey; Hofer, Amy R.

2011-01-01

387

Density estimation by wavelet thresholding  

Microsoft Academic Search

Density estimation is a commonly used test case for nonparametric estimation methods. We explore the asymptotic properties of estimators based on thresholding of empirical wavelet coefficients. Minimax rates of convergence are studied over a large range of Besov function classes $B_{\\\\sigma pq}$ and for a range of global $L'_p$ error measures, $1 \\\\leq p' < \\\\infty$. A single wavelet threshold

David L. Donoho; Iain M. Johnstone; Gérard Kerkyacharian; Dominique Picard

1996-01-01

388

Threshold Hypothesis: Fact or Artifact?  

ERIC Educational Resources Information Center

|The threshold hypothesis (TH) assumes the existence of complex relations between creative abilities and intelligence: linear associations below 120 points of IQ and weaker or lack of associations above the threshold. However, diverse results have been obtained over the last six decades--some confirmed the hypothesis and some rejected it. In this…

Karwowski, Maciej; Gralewski, Jacek

2013-01-01

389

Thermotactile Perception Thresholds Measurement Conditions  

Microsoft Academic Search

The purpose of this paper is to investigate the effects of posture, push force and rate of temperature change on thermotactile thresholds and to clarify suitable measuring conditions for Japanese people. Thermotactile (warm and cold) thresholds on the right middle finger were measured with an HVLab thermal aesthesiometer. Subjects were eight healthy male Japanese students. The effects of posture in

Setsuo MAEDA; Hisataka SAKAKIBARA

2002-01-01

390

Threshold Hypothesis: Fact or Artifact?  

ERIC Educational Resources Information Center

The threshold hypothesis (TH) assumes the existence of complex relations between creative abilities and intelligence: linear associations below 120 points of IQ and weaker or lack of associations above the threshold. However, diverse results have been obtained over the last six decades--some confirmed the hypothesis and some rejected it. In this…

Karwowski, Maciej; Gralewski, Jacek

2013-01-01

391

Scalar-isovector K¯ production close to threshold  

NASA Astrophysics Data System (ADS)

The reaction pp ? dK +¯ has been investigated at excess energies Q = 47.4 and 104.7MeV above the K +¯ threshold at COSY Jülich. Coincident dK+ pairs were detected with the ANKE spectrometer, and subsequently ˜ 2000 events with a missing ¯ invariant mass were identified, which fully populate the Dalitz plot. The joint analysis of invariant mass and angular distributions reveals s-wave dominance between the two kaons, in conjunction with a p-wave between the deuteron and the kaon pair, i.e. K¯ production via the a 0 +(980) channel. Integration of the differential distributions yields total cross-sections of ?( pp ? dK +¯) = (38±2stat±14syst)nb and (190±4stat±39syst)nb for the low and high Q value, respectively.

Dzyuba, A.; Kleber, V.; Büscher, M.; Chernyshev, V. P.; Dymov, S.; Fedorets, P.; Grishina, V.; Hanhart, C.; Hartmann, M.; Hejny, V.; Kondratyuk, L.; Koptev, V.; Kulessa, P.; Maeda, Y.; Mersmann, T.; Mikirtychyants, S.; Nekipelov, M.; Prasuhn, D.; Schleichert, R.; Sibirtsev, A.; Stein, H. J.; Ströher, H.; Zychor, I.

2006-08-01

392

Energy efficient data representation and aggregation with event region detection in wireless sensor networks  

NASA Astrophysics Data System (ADS)

Unlike conventional networks, wireless sensor networks (WSNs) are limited in power, have much smaller memory buffers, and possess relatively slower processing speeds. These characteristics necessitate minimum transfer and storage of information in order to prolong the network lifetime. In this dissertation, we exploit the spatio-temporal nature of sensor data to approximate the current values of the sensors based on readings obtained from neighboring sensors and itself. We propose a Tree based polynomial REGression algorithm, (TREG) that addresses the problem of data compression in wireless sensor networks. Instead of aggregated data, a polynomial function (P) is computed by the regression function, TREG. The coefficients of P are then passed to achieve the following goals: (i) The sink can get attribute values in the regions devoid of sensor nodes, and (ii) Readings over any portion of the region can be obtained at one time by querying the root of the tree. As the size of the data packet from each tree node to its parent remains constant, the proposed scheme scales very well with growing network density or increased coverage area. Since physical attributes exhibit a gradual change over time, we propose an iterative scheme, UPDATE_COEFF, which obviates the need to perform the regression function repeatedly and uses approximations based on previous readings. Extensive simulations are performed on real world data to demonstrate the effectiveness of our proposed aggregation algorithm, TREG. Results reveal that for a network density of 0.0025 nodes/m2, a complete binary tree of depth 4 could provide the absolute error to be less than 6%. A data compression ratio of about 0.02 is achieved using our proposed algorithm, which is almost independent of the tree depth. In addition, our proposed updating scheme makes the aggregation process faster while maintaining the desired error bounds. We also propose a Polynomial-based scheme that addresses the problem of Event Region Detection (PERD) for WSNs. When a single event occurs, a child of the tree sends a Flagged Polynomial (FP) to its parent, if the readings approximated by it falls outside the data range defining the existing phenomenon. After the aggregation process is over, the root having the two polynomials, P and FP can be queried for FP (approximating the new event region) instead of flooding the whole network. For multiple such events, instead of computing a polynomial corresponding to each new event, areas with same data range are combined by the corresponding tree nodes and the aggregated coefficients are passed on. Results reveal that a new event can be detected by PERD while error in detection remains constant and is less than a threshold of 10%. As the node density increases, accuracy and delay for event detection are found to remain almost constant, making PERD highly scalable. Whenever an event occurs in a WSN, data is generated by closeby sensors and relaying the data to the base station (BS) make sensors closer to the BS run out of energy at a much faster rate than sensors in other parts of the network. This gives rise to an unequal distribution of residual energy in the network and makes those sensors with lower remaining energy level die at much faster rate than others. We propose a scheme for enhancing network Lifetime using mobile cluster heads (CH) in a WSN. To maintain remaining energy more evenly, some energy-rich nodes are designated as CHs which move in a controlled manner towards sensors rich in energy and data. This eliminates multihop transmission required by the static sensors and thus increases the overall lifetime of the WSN. We combine the idea of clustering and mobile CH to first form clusters of static sensor nodes. A collaborative strategy among the CHs further increases the lifetime of the network. Time taken for transmitting data to the BS is reduced further by making the CHs follow a connectivity strategy that always maintain a connected path to the BS. Spatial correlation of sensor data can be further exploited for dynamic channel selection

Banerjee, Torsha

393

Ecohydrology on the Threshold?  

NASA Astrophysics Data System (ADS)

This presentation suggests that there are three major limitations to the development of ecohydrology as a coherent disciplinary area. One of the principal controls and feedbacks on patterns of plants and water in the environment is the form of the landscape and landscape-forming processes. Yet (eco)geomorphology is typically overlooked as a topic for ecohydrological investigation. Thus, the process domains used to explain patterns is typically overly restricted. As surface change controls the connectivity of other process, this restriction is significant. However, even when surface change is incorporated, there is often an emphasis on subdisciplinary areas, so that the investigation of patterns across process domains is not carried out in a holistic way. For example, studies of the feedbacks of vegetation on flow resistance are carried out significantly differently when considering wind and water flows (and indeed differently for water flows on hillslopes compared to in channels). Human action is the most important global control on ecohydrology, either from a top-down perspective through climate change, or from a bottom-up perspective through land use and land-use change. The actions of people on ecohydrological and ecogeomorphic processes, though, are typically considered in a static way. Techniques of agent-based modelling are being developed to overcome this limitation, but there need to be parallel developments in field techniques to address the data requirements and empirical underpinnings of such approaches. I argue that to cross the threshold into becoming a more mature discipline ecohydrology/ecogeomorphology needs to take on board the limitations of representations of process, pattern and people. Using examples from studies of land degradation in drylands, as well as from more temperate settings, I will suggest how progress may start to be made.

Wainwright, John

2013-04-01

394

Neutron thresholds to resonant analogue states  

Microsoft Academic Search

The anomalous energy behaviour of the neutron threshold to a resonant analogue state is investigated in detail. The analysis is applied to recently studied reactions of the type A(d, np)A but can equally well be applied to reactions involving other projectiles. To avoid all three-body effects, the reaction is assumed to be a sequential process, i.e. the resonant intermediate analogue

R. O. Stephen

1967-01-01

395

Near threshold studies of photoelectron satellites  

SciTech Connect

Photoelectron spectroscopy and synchrotron radiation have been used to study correlation effects in the rare gases: He, Ne, Ar, Kr, and Xe. Two kinds of time-of-flight electron analyzers were employed to examine photoionization very close to threshold and at higher kinetic energies. Partial cross sections and angular distributions have been measured for a number of photoelectron satellites. The shake-off probability has been determined at some inner-shell resonances. 121 refs., 28 figs., 13 tabs.

Heimann, P.A.

1986-11-01

396

Development of a Cerenkov radiation sensor to detect low-energy beta-particles.  

PubMed

We fabricated a novel fiber-optic Cerenkov radiation sensor using a Cerenkov radiator for measuring beta-particles. Instead of employing a scintillator, transparent liquids having various refractive indices were used as a Cerenkov radiator to serve as a sensing material. The experimental results showed that the amount of Cerenkov radiation due to the interaction with beta-particles increased as the refractive index of the Cerenkov radiator was increased as a results of a decrease of the Cerenkov threshold energy for electrons. PMID:23582496

Yoo, Wook Jae; Han, Ki-Tek; Shin, Sang Hun; Seo, Jeong Ki; Jeon, Dayeong; Lee, Bongsoo

2013-03-28

397

Identifying Thresholds for Ecosystem-Based Management  

PubMed Central

Background One of the greatest obstacles to moving ecosystem-based management (EBM) from concept to practice is the lack of a systematic approach to defining ecosystem-level decision criteria, or reference points that trigger management action. Methodology/Principal Findings To assist resource managers and policymakers in developing EBM decision criteria, we introduce a quantitative, transferable method for identifying utility thresholds. A utility threshold is the level of human-induced pressure (e.g., pollution) at which small changes produce substantial improvements toward the EBM goal of protecting an ecosystem's structural (e.g., diversity) and functional (e.g., resilience) attributes. The analytical approach is based on the detection of nonlinearities in relationships between ecosystem attributes and pressures. We illustrate the method with a hypothetical case study of (1) fishing and (2) nearshore habitat pressure using an empirically-validated marine ecosystem model for British Columbia, Canada, and derive numerical threshold values in terms of the density of two empirically-tractable indicator groups, sablefish and jellyfish. We also describe how to incorporate uncertainty into the estimation of utility thresholds and highlight their value in the context of understanding EBM trade-offs. Conclusions/Significance For any policy scenario, an understanding of utility thresholds provides insight into the amount and type of management intervention required to make significant progress toward improved ecosystem structure and function. The approach outlined in this paper can be applied in the context of single or multiple human-induced pressures, to any marine, freshwater, or terrestrial ecosystem, and should facilitate more effective management.

Samhouri, Jameal F.; Levin, Phillip S.; Ainsworth, Cameron H.

2010-01-01

398

Threshold collision-induced dissociation of Sr2+(H2O)x complexes (x=1-6): An experimental and theoretical investigation of the complete inner shell hydration energies of Sr2+  

NASA Astrophysics Data System (ADS)

The sequential bond energies of Sr2+(H2O)x complexes, where x=1-6, are determined by threshold collision-induced dissociation using a guided ion beam tandem mass spectrometer equipped with an electrospray ionization source. The electrospray source produces an initial distribution of Sr2+(H2O)x complexes, where x=6-9. Smaller Sr2+(H2O)x complexes, where x=1-5, are accessed using a recently developed in-source fragmentation technique that takes place in the high pressure region of a rf-only hexapole ion guide. This work constitutes the first experimental study for the complete inner shell of any multiply charged ion. The kinetic energy dependent cross sections are determined over a wide energy range to monitor all possible dissociation products and are modeled to obtain 0 and 298 K binding energies for loss of a single water molecule. These binding energies decrease monotonically for the Sr2+(H2O) complex to Sr2+(H2O)6. Our experimental results agree well with previous literature results obtained by equilibrium and kinetic studies for x=5 and 6. Because there has been limited theory for the hydration of Sr2+, we also present an in-depth theoretical study on the energetics of the Sr2+(H2O)x systems by employing several levels of theory with multiple effective core potentials for Sr and different basis sets for the water molecules.

Carl, D. R.; Chatterjee, B. K.; Armentrout, P. B.

2010-01-01

399

Valence calculations of lanthanide anion binding energies: 6p and 6s attachments to 4fm(5d+6s+6p)3 thresholds  

NASA Astrophysics Data System (ADS)

Relativistic configuration-interaction calculations have been performed for anion states representing 6p attachments to 4fm5d6s2 states in Gd and Tb as well as 6s attachments to 4fm5d26s thresholds in Pr and Gd. The 4f subshell was treated as corelike with the same occupancy in all correlation configurations, and recently developed methods for reducing the complexity of the 4fm subgroup were also employed. Results predict a single weakly bound (24meV) even state for Pr- , 12 even states and three odd states for Gd- (the lowest level having an electron affinity of 234meV ), and six odd states for Tb- . The lowest 4f85d6s26p Tb- state is bound relative to the neutral 4f96s2 ground state by 88meV , indicating that the Tb- ground state may actually be an attachment to the first excited state of the neutral atom. Revised calculations and analyses of the much simpler Lu- , La- , and Ce- anions are also presented.

O'Malley, Steven M.; Beck, Donald R.

2009-01-01

400

Bayesian estimation of dose thresholds.  

PubMed

An example is described of Bayesian estimation of radiation absorbed dose thresholds (subsequently simply referred to as dose thresholds) using a specific parametric model applied to a data set on mice exposed to 60Co gamma rays and fission neutrons. A Weibull based relative risk model with a dose threshold parameter was used to analyse, as an example, lung cancer mortality and determine the posterior density for the threshold dose after single exposures to 60Co gamma rays or fission neutrons from the JANUS reactor at Argonne National Laboratory. The data consisted of survival, censoring times and cause of death information for male B6CF1 unexposed and exposed mice. The 60Co gamma whole-body doses for the two exposed groups were 0.86 and 1.37 Gy. The neutron whole-body doses were 0.19 and 0.38 Gy. Marginal posterior densities for the dose thresholds for neutron and gamma radiation were calculated with numerical integration and found to have quite different shapes. The density of the threshold for 60Co is unimodal with a mode at about 0.50 Gy. The threshold density for fission neutrons declines monotonically from a maximum value at zero with increasing doses. The posterior densities for all other parameters were similar for the two radiation types. PMID:12593429

Groer, P G; Carnes, B A

2003-01-01

401

Finding thresholds for image segmentation  

NASA Astrophysics Data System (ADS)

Segmentation methods for images often have cost functions which evaluate the (dis)similarity between pixels or segments. Thresholds on cost values are then used to decide whether or not to grow, join or split segments. The results for a given image critically depend on the selection of the threshold values. In remote sensing, a too low threshold will split up regions of constant ground cover and a too high threshold will join adjacent regions of different ground cover. Optimal thresholds can be determined using different classes of methods: generating cost value distributions from the original image; obtaining statistical distributions from segmented images; comparing a 'true' segmentation with the results of segmentation using a range of thresholds. A so-called 'true' segmentation can be derived from human expert segmentations or from maps obtained by ground surveys or segmentation of higher resolution images. Also artificial images can be generated having the advantage that the segmentation is known to sub-pixel level. Several methods for threshold determination are described for a hybrid segmentation method developed by us. Measures are described for comparison of two segmentations. Results are evaluated using several (parts of) LANDSAT images and artificial generated images.

Schouten, Theo E.; Klein Gebbinck, Maurice S.; Schoenmakers, Ron P.; Wilkinson, Graeme G.

1994-12-01

402

Specific survivin dual fluorescence resonance energy transfer molecular beacons for detection of human bladder cancer cells  

Microsoft Academic Search

Aim:Survivin molecular beacons can be used to detect bladder cancer cells in urine samples non-invasively. The aim of this study is to improve the specificity of detection of bladder cancer cells using survivin dual fluorescence resonance energy transfer molecular beacons (FRET MBs) that have fluorophores forming one donor-acceptor pair.Methods:Survivin-targeting dual fluorescence resonance energy transfer molecular beacons with unique target sequences

Zhi-qiang Wang; Jun Zhao; Jin Zeng; Kai-jie Wu; Yu-le Chen; Xin-yang Wang; Luke S Chang; Da-lin He

2011-01-01

403

Teager–Kaiser Energy Operation of Surface EMG Improves Muscle Activity Onset Detection  

Microsoft Academic Search

This study presents a novel method for detection of the onset time of muscle activity using surface electromyogram (EMG) signals.\\u000a The method takes advantage of the nonlinear properties of the Teager–Kaiser energy (TKE) operator, which simultaneously considers\\u000a the amplitude and instantaneous frequency of the surface EMG, and therefore increases the prospects of muscle activity detection.\\u000a To detect the onset time

Xiaoyan Li; Ping Zhou; Alexander S. Aruin

2007-01-01

404

First simultaneous detection of PeV energy burst from the Crab Nebula  

NASA Astrophysics Data System (ADS)

The simultaneous detection of a PeV burst from the Crab Nebula is reported. The detection was made on February 23, 1989 by experiments in the Kolar Gold Fields in southern India and the Baksan Valley in the northern Caucasus mountains. These findings lend support to the theory that supernovae are the sources of cosmic rays with energies up to 10 to the 20th eV. The methods used to make the present detection are described.

Acharya, B. S.; Rao, M. V. S.; Sivaprasad, K.; Sreekantan, B. V.; Vishwanath, P. R.

1990-09-01

405

Fluorescent silica nanoparticle-based probe for the detection of ozone via fluorescence resonance energy transfer.  

PubMed

A fluorescence resonance energy transfer (FRET) platform for the detection of ozone was developed by combining the overlap of the fluorescence spectrum of Ru(bpy)3(2+)-doped silica nanoparticles with the absorption spectrum of indigo carmine at around 600 nm. This FRET system can be used to detect ozone simply within 10 min. Simple qualitative ozone detection methods using cotton swabs or paper were also developed. PMID:24049767

Qi, Wenjing; Wu, Di; Zhao, Jianming; Liu, Zhongyuan; Xu, Min; Anjum, Saima; Xu, Guobao

2013-09-30

406

Optimal spatial sampling interval for damage detection by curvature or strain energy mode shapes  

Microsoft Academic Search

Vibration-based methods of non-destructive damage detection utilizing curvature or strain energy mode shapes have been applied in a variety of applications. Attractive features of these methods include high sensitivity to damage and instant determination of the damage location. However, the quality of damage detection achieved in practice depends upon determining a proper sampling interval for discretization of the displacement mode

Edward Sazonov; Powsiri Klinkhachorn

2005-01-01

407

Procedure Call Duplication: Minimization of Energy Consumption with Constrained Error Detection Latency  

Microsoft Academic Search

This paper presents a new software technique for detecting transient hardware errors. The objective is to guarantee data integrity in the presence of transient errors and to minimize energy consumption at the same time. Basically, we duplicate computations and compare their results to detect errors. There are three choices for duplicate computations: (1) duplicating every statement in the program and

Oh Nahmsuk; Edward J. Mccluskey

2001-01-01

408

Harmonic Analysis of Polynomial Threshold Functions  

Microsoft Academic Search

The analysis of linear threshold Boolean functions has recently attracted the attention of those interested in circuit complexity as well as of those interested in neural networks. Here a generalization of linear threshold functions is defined, namely, polynomial threshold functions, and its relation to the class of linear threshold functions is investigated. A Boolean function is polynomial threshold if it

Jehoshua Bruck

1990-01-01

409

A study of wavelet thresholding denoising  

Microsoft Academic Search

This paper introduces the principle of wavelet multiresolution analysis. Four kinds of threshold selection rules and three methods of threshold processing are given. According to the computer simulation, the best rule of estimating the threshold is found, which is combined with three kinds of threshold processing methods to denoise the same noisy signal. The best method of threshold processing is

Dai-Fei Guo; Wei-Hong Zhu; Zhen-Ming Gao; Jian-Qiang Zhang

2000-01-01

410

Identification of Low-Dimensional Energy Containing\\/Flux Transporting Eddy Motion in the Atmospheric Surface Layer Using Wavelet Thresholding Methods  

Microsoft Academic Search

The partitioning of turbulent perturbations into a `low-dimensional' active part responsible for much of the turbulent energy and fluxes and a `high-dimensional' passive part that contributes little to turbulent energy and transport dynamics is investigated using atmospheric surface-layer (ASL) measurements. It is shown that such a partitioning scheme can be achieved by transforming the ASL measurements into a domain that

Gabriel Katul; Brani Vidakovic

1998-01-01

411

Generation, propagation, and detection of high energy solar cosmic rays  

Microsoft Academic Search

The data on energetic (E ? 1012eV) solar cosmic ray generation are presented for the event of September 29, 1989. Charged particle acceleration mechanisms in the flares of an energy below E = 1011 - 1012eV are substantiated.

V. V. Borog; A. Yu. Burinsky; V. V. Dronov; E. V. Kolomeets; V. M. Smirnov; E. A. Chebakova

1997-01-01

412

Optimum General Threshold Secret Sharing  

Microsoft Academic Search

An important issue of a secret sharing (SS) scheme is to minimize the entropy of a share. This issue is perfectly resolved for the simpler classes called (k,n)- threshold SS (TSS) scheme and (k,L,n)-threshold ramp SS (TRSS) scheme. That is, for these two classes, an opti- mum construction which minimizes the entropy of a share was presented. The goal of

Maki Yoshida; Toru Fujiwara; Marc Fossorier

2008-01-01

413

Detecting special nuclear materials in suspect containers using high-energy gamma rays emitted by fission products  

DOEpatents

A method and a system for detecting the presence of special nuclear materials in a suspect container. The system and its method include irradiating the suspect container with a beam of neutrons, so as to induce a thermal fission in a portion of the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the thermal fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

Norman, Eric B. (Oakland, CA); Prussin, Stanley G. (Kensington, CA)

2009-01-06

414

Detecting special nuclear materials in suspect containers using high-energy gamma rays emitted by fission products  

DOEpatents

A method and a system for detecting the presence of special nuclear materials in a suspect container. The system and its method include irradiating the suspect container with a beam of neutrons, so as to induce a thermal fission in a portion of the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the thermal fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

Norman, Eric B [Oakland, CA; Prussin, Stanley G [Kensington, CA

2009-05-05

415

Detecting special nuclear materials in suspect containers using high-energy gamma rays emitted by fission products  

DOEpatents

A method and a system for detecting the presence of special nuclear materials in a suspect container. The system and its method include irradiating the suspect container with a beam of neutrons, so as to induce a thermal fission in a portion of the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the thermal fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

Norman, Eric B. (Oakland, CA); Prussin, Stanley G. (Kensington, CA)

2009-01-27

416

Threshold models in radiation carcinogenesis  

SciTech Connect

Cancer incidence and mortality data from the atomic bomb survivors cohort has been analyzed to allow for the possibility of a threshold dose response. The same dose-response models as used in the original papers were fit to the data. The estimated cancer incidence from the fitted models over-predicted the observed cancer incidence in the lowest exposure group. This is consistent with a threshold or nonlinear dose-response at low-doses. Thresholds were added to the dose-response models and the range of possible thresholds is shown for both solid tumor cancers as well as the different leukemia types. This analysis suggests that the A-bomb cancer incidence data agree more with a threshold or nonlinear dose-response model than a purely linear model although the linear model is statistically equivalent. This observation is not found with the mortality data. For both the incidence data and the mortality data the addition of a threshold term significantly improves the fit to the linear or linear-quadratic dose response for both total leukemias and also for the leukemia subtypes of ALL, AML, and CML.

Hoel, D.G.; Li, P. [Medical Univ. of South Carolina, Charleston, SC (United States). Dept. of Biometry and Epidemiology

1998-09-01

417

Detection of high-energy gamma rays from winter thunderclouds.  

PubMed

A report is made on a comprehensive observation of a burstlike gamma-ray emission from thunderclouds on the Sea of Japan, during strong thunderstorms on 6 January 2007. The detected emission, lasting for approximately 40 sec, preceded cloud-to-ground lightning discharges. The burst spectrum, extending to 10 MeV, can be interpreted as consisting of bremsstrahlung photons originating from relativistic electrons. This ground-based observation provides the first clear evidence that strong electric fields in thunderclouds can continuously accelerate electrons beyond 10 MeV prior to lightning discharges. PMID:17995261

Tsuchiya, H; Enoto, T; Yamada, S; Yuasa, T; Kawaharada, M; Kitaguchi, T; Kokubun, M; Kato, H; Okano, M; Nakamura, S; Makishima, K

2007-10-17

418

Frequency-Domain Differential Energy Detection Based on Extreme Statistics for OFDM Source Sensing  

Microsoft Academic Search

This paper presents a novel differential energy detection scheme based on extremes of order statistics for sensing OFDM signals. The underlying initiative of this approach is applying the order statistics of the differential Energy Spectral Density in frequency domain. The proposed technique takes advantage of the channel selectivity which is inherited from high data-rate communications. The introduced frequency diversity allows

Parisa Cheraghi; Yi Ma; Rahim Tafazolli

2011-01-01

419

Simultaneous Detection of High Energy Phosphates and Metabolites of Glycolysis and the Krebs Cycle by HPLC  

Microsoft Academic Search

For the detailed analysis of energy metabolism, a HPLC method is described allowing the single-run separation and quantification of most metabolites from glycolysis and the Krebs cycle including the high energy phosphates. With a detection limit in the picomolar range this method is even applicable when only small sample sizes of tissue are obtained.

Achim M. Vogt; Cordula Ackermann; Tanja Noe; Detlef Jensen; Wolfgang Kübler

1998-01-01

420

Fuzzy logic expert system for automated damage detection from changes in strain energy mode shapes  

Microsoft Academic Search

In recent years, researchers have developed several methods for damage detection in structures employing strain energy or curvature mode shapes. Experience shows that mode shape methods are highly sensitive to measurement noise. Such sensitivity is a direct result of the second derivative applied to the displacement mode shapes, which produces curvature mode shapes. Calculation of strain energy mode shapes includes

EDWARD S. SAZONOVa; Powsiri Klinkhachorn; Hota V. S. Gangarao; Udaya B. Halabe

2002-01-01

421

Engineering energy-efficient target detection applications in Wireless Sensor Networks  

Microsoft Academic Search

This paper addresses the problem of engineering energy-efficient target detection applications using unattended Wireless Sensor Networks (WSNs) for long-lasting surveillance of areas of interest. As battery energy depletion is an issue in this context, an approach consists of switching on and off sensing and communication modules of wireless sensors according to duty cycles. Making these modules work in an intermittent

Paolo Medagliani; Jeremie Leguay; Vincent Gayt; Mario Lopez-Ramost; Gian Luigi Ferrari

2010-01-01

422

In-situ fault detection apparatus and method for an encased energy storing device  

DOEpatents

An apparatus and method for detecting a breach in an electrically insulating surface of an electrically conductive power system enclosure within which a number of series connected energy storing devices are disposed. The energy storing devices disposed in the enclosure are connected to a series power connection. A detector is coupled to the series connection and detects a change of state in a test signal derived from the series connected energy storing devices. The detector detects a breach in the insulating layer of the enclosure by detecting a state change in the test signal from a nominal state to a non-nominal state. A voltage detector detects a state change of the test signals from a nominal state, represented by a voltage of a selected end energy storing device, to a non-nominal state, represented by a voltage that substantially exceeds the voltage of the selected opposing end energy storing device. Alternatively, the detector may comprise a signal generator that produces the test signal as a time-varying or modulated test signal and injects the test signal into the series connection. The detector detects the state change of the time-varying or modulated test signal from a nominal state, represented by a signal substantially equivalent to the test signal, to a non-nominal state, representative by an absence of the test signal.

Hagen, Ronald A. (Stillwater, MN); Comte, Christophe (Montreal, CA); Knudson, Orlin B. (Vadnais Heights, MN); Rosenthal, Brian (Stillwater, MN); Rouillard, Jean (Saint-Luc, CA)

2000-01-01

423

NOSTOS: a spherical TPC to detect low energy neutrinos  

NASA Astrophysics Data System (ADS)

A novel low-energy (~few keV) neutrino-oscillation experiment NOSTOS, combining a strong tritium source and a high pressure spherical Time Projection Chamber (TPC) detector 10 m in radius has been recently proposed. The oscillation of neutrinos of such energies occurs within the size of the detector itself, potentially allowing for a very precise (and rather systematics-free) measure of the oscillation parameters, in particular, of the smaller mixing angle ?13, which value could be determined for the first time. This detector could also be sensitive to the neutrino magnetic moment and be capable of accurately measure the Weinberg angle at low energy. The same apparatus, filled with high pressure Xenon, exhibits a high sensitivity as a Super Nova neutrino detector with extra galactic sensitivity. The outstanding benefits of the new concept of the spherical TPC will be presented, as well as the issues to be demonstrated in the near future by an ongoing R&D. The very first results of small prototype in operation in Saclay are shown.

Aune, S.; Colas, P.; Dolbeau, J.; Fanourakis, G.; Ribas, E. Ferrer; Geralis, T.; Giomataris, Y.; Gorodetzky, P.; Gounaris, G. J.; Irastorza, I. G.; Kousouris, K.; Lepeltier, V.; Patzak, T.; Paschos, E. A.; Salin, P.; Savvidis, I.; Vergados, J. D.

2005-09-01

424

Threshold Law for Attractive Inverse-Cube Interactions  

NASA Astrophysics Data System (ADS)

For scattering by potentials with attractive inverse-cube (-C3/r3) tails, the threshold law for elastic collisions is presented. The expansion of the scattering phase shift contains all terms up to and including O(k2) and only relies on the value of the threshold quantum number’s remainder ??[0,1), which accounts for short-range deviations of the full potential from the pure -C3/r3 form. In contrast to previous approaches, the threshold law presented provides a connection to the regular solution at zero energy as well as to the position of a weakly bound s-wave state.

Müller, Tim-Oliver

2013-06-01

425

Surface target edge detection based on local energy model in sea clutter background  

NASA Astrophysics Data System (ADS)

Most of edge detection algorithms are based on the gradient method. When texture is complex, especially in scale light background, the image may be cluttered. Thus, it is hard to find useful information in the edge map. In this article, a local energy model, which is relative to Human Vision System (HVS), is proposed to detect robust and useful edges. We give non-classic receptive field (Non-CRF) methods to detect interested edges. The experimental results show that the method we proposed in this paper is much better than gradient methods in detecting edges interested.

Su, Wenbo; Shi, Zelin; Qi, Lin

2012-10-01

426

GRBs detected by the HETE-2 satellite  

Microsoft Academic Search

Between the years 2000 and 2006 HETE-2 detected several hundreds GRBs and localized 84 of them, with a precision even as low as few arcminutes and a delay even of only one minute. The low energy threshold of the instruments made HETE-2 particularly apt for detecting X-Ray Flashes and X-Ray Rich GRBs and for the study of the soft part

Filip Munz; Graziella Pizzichini

2009-01-01

427

Detection methods for cereal grains treated with low and high energy electrons  

NASA Astrophysics Data System (ADS)

Cereal grains can be treated with low energy (<300keV) or high energy (1-10MeV) electrons for decontamination of phytopathogenic and spoilage organisms. In this preliminary study, wheat and barley samples were treated with low energy electrons of 145keV or high energy electrons of 10MeV. To identify the electron treatment, different detection methods have been investigated: (1) photostimulated luminescence (PSL), (2) thermoluminescence (TL), (3) electron spin resonance (ESR) and (4) DNA Comet Assay. These four methods are already standardised at a European level and are now adopted as general Codex methods for detection of irradiated foodstuffs. The results suggest that the most suitable detection methods for electron-treated grains are the PSL and TL methods. The results from the other two methods (ESR and Comet Assay) are not so promising because they seem only to be applicable in special cases.

Cutrubinis, Mihalis; Delincée, Henry; Stahl, Mario; Röder, Olaf; Schaller, Hans Jürgen

2005-04-01

428

Damage thresholds for terahertz radiation  

NASA Astrophysics Data System (ADS)

Several international organizations establish minimum safety standards to ensure that workers and the general population are protected against adverse health effects associated with electromagnetic radiation. Suitable standards are typically defined using published experimental data. To date, few experimental studies have been conducted at Terahertz (THz) frequencies, and as a result, current THz standards have been defined using extrapolated estimates from neighboring spectral regions. In this study, we used computational modeling and experimental approaches to determine tissue-damage thresholds at THz frequencies. For the computational modeling efforts, we used the Arrhenius damage integral to predict damage-thresholds. We determined thresholds experimentally for both long (minutes) and short (seconds) THz exposures. For the long exposure studies, we used an in-house molecular gas THz laser (?= 1.89 THz, 189.92 mW/cm2, 10 minutes) and excised porcine skin. For the short exposure studies, we used the Free Electron Laser (FEL) at Jefferson Laboratory (?= 0.1-1.0 THz, 2.0-14.0 mW/cm2, 2 seconds) and wet chamois cloths. Thresholds were determined using conventional damage score determination and probit analysis techniques, and tissue temperatures were measured using infrared thermographic techniques. We found that the FEL was ideal for tissue damage studies, while our in-house THz source was not suitable to determine tissue damage thresholds. Using experimental data, the tissue damage threshold (ED50) was determined to be 7.16 W/cm2. This value was in well agreement with that predicted using our computational models. We hope that knowledge of tissue-damage thresholds at THz frequencies helps to ensure the safe use of THz radiation.

Dalzell, Danielle R.; McQuade, Jill; Vincelette, Rebecca; Ibey, Bennet; Payne, Jason; Thomas, Robert; Roach, W. P.; Roth, Caleb L.; Wilmink, Gerald J.

2010-02-01

429

Two-photon above-threshold ionization of hydrogen over the photon energy range from 15 eV to 50 keV  

SciTech Connect

We investigate the absorption of two identical photons from the ground state of hydrogen-like atoms over an energy range that extends beyond that explored up to now. Our approach is based on a hybrid formula, valid in second-order perturbation theory, in which the A{sup 2} contribution from the nonrelativistic Hamiltonian is treated exactly, while the A{center_dot}P contribution is calculated in dipole approximation. We find that, at least up to 50 keV, the nonrelativistic dipole approximation, based only on the A{center_dot}P contribution, determines the values of the total cross section. Our numerical results, covering photon energies from 90 nm (13.7 eV) to 0.0248 nm (50 keV) are in very good agreement with most previous theoretical works. Differences with recent results are discussed.

Florescu, Viorica; Budriga, Olimpia; Bachau, Henri [Department of Physics and Centre for Advanced Quantum Physics, University of Bucharest, MG-11, R-077125 Bucharest-Magurele (Romania); National Institute for Laser, Plasma and Radiation Physics, R-077125 Bucharest-Magurele (Romania); Centre des Lasers Intenses et Applications, Universite Bordeaux I-CNRS-CEA, F-33405 Talence Cedex (France)

2011-09-15

430

Yield measurements for resonances above the multi-? threshold in 20Ne  

NASA Astrophysics Data System (ADS)

The reaction 16O(?,20Ne), has been studied with beam energies from 23.0 to 29.0 MeV in 100-keV steps. Resonant states in 20Ne have been populated which are above the multi-? decay threshold and that decay via 8Be + 8Be + ? and 8Be + 12C(02+). An array of four silicon-strip detectors was used for the detection of four of the five emitted ? particles, enabling the full reconstruction of the kinematics. The normalized yields have been obtained, with indications of significant strength above 24.5 MeV arising from several possible resonances.

Kokalova, Tz.; Freer, M.; Curtis, N.; Ashwood, N. I.; Barr, M.; Malcolm, J. D.; Wheldon, C.; Ziman, V. A.; Almaraz-Calderon, S.; Aprahamian, A.; Bucher, B.; Couder, M.; Fang, X.; Jung, F.; Lu, W.; Roberts, A.; Tan, W. P.; Copp, P.; Lesher, S. R.

2013-05-01

431

Lower and upper estimates on the excitation threshold for breathers in discrete nonlinear Schroedinger lattices  

SciTech Connect

We propose analytical lower and upper estimates on the excitation threshold for breathers (in the form of spatially localized and time periodic solutions) in discrete nonlinear Schroedinger (DNLS) lattices with power nonlinearity. The estimation, depending explicitly on the lattice parameters, is derived by a combination of a comparison argument on appropriate lower bounds depending on the frequency of each solution with a simple and justified heuristic argument. The numerical studies verify that the analytical estimates can be of particular usefulness, as a simple analytical detection of the activation energy for breathers in DNLS lattices.

Cuevas, J. [Departamento de Fisica Aplicada I, University of Sevilla, Escuela Universitaria Politenica, C/Virgen de Africa, 7, 41011 Sevilla (Spain); Karachalios, N. I. [Department of Mathematics, University of the Aegean, Karlovassi, 83200 Samos (Greece); Palmero, F. [Departamento de Fisica Aplicada I, University of Sevilla, ETSI Informatica, Avd. Reina Mercedes s/n, 41012 Sevilla (Spain)

2009-11-15

432

A portable energy-sensitive cosmic neutron detection instrument.  

PubMed

The construction and testing of a portable energy-sensitive neutron instrument are described. This instrument has been designed and constructed for the primary purpose of characterizing cosmic-ray neutron fields in the upper atmosphere and in cosmic reference field facilities. The instrument comprises a helium-3 proportional counter surrounded by 15 mm of lead and 140 mm of polyethylene creating a spherical structure with a diameter of 34 cm. The instrument also incorporates 12 boron-coated diodes, six on the outside of the polyethylene layer with six placed within the structure. The dimensions, materials, and arrangement of these in the instrument have previously been optimized with the MCNPX Monte Carlo simulation software to provide a compromise between the requirements of portability and spectral response. Testing took place at several locations and experimental data from the instrument's operation at the high-altitude Jungfraujoch laboratory in the Swiss alps are presented. PMID:18315287

Monk, S D; Joyce, M J; Jarrah, Z; King, D; Oppenheim, M

2008-02-01

433

Detection of high-energy delayed gammas for nuclear waste packages characterization  

NASA Astrophysics Data System (ADS)

Methods based on photon activation analysis (PAA) have been developed by CEA LIST for several years, in order to assay actinides inside nuclear waste packages. These techniques were primarily based on the detection of delayed neutrons emitted by fission products. To overcome some limitations related to neutrons, CEA LIST has worked on the detection of high-energy delayed gammas (E>3 MeV), which are simultaneously emitted by fission products along with delayed neutrons. Since the emission yield is more important for high-energy delayed gammas than delayed neutrons and because they are less sensitive to hydrogenous material, high-energy delayed gammas are a solution of interest in order to improve the accuracy of these techniques. In this article, we present new experimental results demonstrating the feasibility of high-energy delayed gamma detection for nuclear waste packages characterization. Experiments have been carried out in the PAA facility called SAPHIR, which is located in CEA Saclay. The most important part of our work has been carried out on an 870 l mock-up package. Some experimental techniques, initially based on delayed neutron detection (altitude scan, photofission tomography), have been successfully applied for the first time using high-energy delayed gamma detection.

Carrel, F.; Agelou, M.; Gmar, M.; Lainé, F.

2011-10-01

434

Benefits of texture analysis of dual energy CT for Computer-Aided pulmonary embolism detection.  

PubMed

Pulmonary embolism is an avoidable cause of death if treated immediately but delays in diagnosis and treatment lead to an increased risk. Computer-assisted image analysis of both unenhanced and contrast-enhanced computed tomography (CT) have proven useful for diagnosis of pulmonary embolism. Dual energy CT provides additional information over the standard single energy scan by generating four-dimensional (4D) data, in our case with 11 energy levels in 3D. In this paper a 4D texture analysis method capable of detecting pulmonary embolism in dual energy CT is presented. The method uses wavelet-based visual words together with an automatic geodesic-based region of interest detection algorithm to characterize the texture properties of each lung lobe. Results show an increase in performance with respect to the single energy CT analysis, as well as an accuracy gain compared to preliminary work on a small dataset. PMID:24110602

Foncubierta-Rodriguez, Antonio; Jimenez Del Toro, Oscar Alfonso; Platon, Alexandra; Poletti, Pierre-Alexandre; Muller, Henning; Depeursinge, Adrien

2013-07-01

435

Low-energy ion spectral peaks detected by CRRES in the plasma sheet  

SciTech Connect

The authors have examined energy-versus time color spectrograms compiled by the low-energy plasma analyzer (LEPA) during 140 orbits of the Combined Release Radiation Effects Satellite (CRRES). Over the period of interest, the apogee of CRRES` orbit precessed from near dawn to near midnight. During more than half of the orbits LEPA detected low-energy ion spectral peaks (LISPs) that fell into two categories: isotropic and field aligned. Isotropic LISPs were detected most frequently in the 0200-0500 magnetic local time (MLT) sector and relatively high levels of Kp. They always were detected in the company of >10 keV plasma sheet electrons and appeared in one or, at most, two LEPA energy channels. Field-aligned LISPs were evenly distributed over the sampled MLT secto