Anomalous frequency-dependent ionic conductivity of lesion-laden human-brain tissue

NASA Astrophysics Data System (ADS)

Emin, David; Akhtari, Massoud; Fallah, Aria; Vinters, Harry V.; Mathern, Gary W.

2017-10-01

We study the effect of lesions on our four-electrode measurements of the ionic conductivity of (˜1 cm3) samples of human brain excised from patients undergoing pediatric epilepsy surgery. For most (˜94%) samples, the low-frequency ionic conductivity rises upon increasing the applied frequency. We attributed this behavior to the long-range (˜0.4 mm) diffusion of solvated sodium cations before encountering intrinsic impenetrable blockages such as cell membranes, blood vessels, and cell walls. By contrast, the low-frequency ionic conductivity of some (˜6%) brain-tissue samples falls with increasing applied frequency. We attribute this unusual frequency-dependence to the electric-field induced liberation of sodium cations from traps introduced by the unusually severe pathology observed in samples from these patients. Thus, the anomalous frequency-dependence of the ionic conductivity indicates trap-producing brain lesions.

Split Hopkinson resonant bar test for sonic-frequency acoustic velocity and attenuation measurements of small, isotropic geological samples.

PubMed

Nakagawa, Seiji

2011-04-01

Mechanical properties (seismic velocities and attenuation) of geological materials are often frequency dependent, which necessitates measurements of the properties at frequencies relevant to a problem at hand. Conventional acoustic resonant bar tests allow measuring seismic properties of rocks and sediments at sonic frequencies (several kilohertz) that are close to the frequencies employed for geophysical exploration of oil and gas resources. However, the tests require a long, slender sample, which is often difficult to obtain from the deep subsurface or from weak and fractured geological formations. In this paper, an alternative measurement technique to conventional resonant bar tests is presented. This technique uses only a small, jacketed rock or sediment core sample mediating a pair of long, metal extension bars with attached seismic source and receiver-the same geometry as the split Hopkinson pressure bar test for large-strain, dynamic impact experiments. Because of the length and mass added to the sample, the resonance frequency of the entire system can be lowered significantly, compared to the sample alone. The experiment can be conducted under elevated confining pressures up to tens of MPa and temperatures above 100 [ordinal indicator, masculine]C, and concurrently with x-ray CT imaging. The described split Hopkinson resonant bar test is applied in two steps. First, extension and torsion-mode resonance frequencies and attenuation of the entire system are measured. Next, numerical inversions for the complex Young's and shear moduli of the sample are performed. One particularly important step is the correction of the inverted Young's moduli for the effect of sample-rod interfaces. Examples of the application are given for homogeneous, isotropic polymer samples, and a natural rock sample. © 2011 American Institute of Physics

Method and apparatus for generating motor current spectra to enhance motor system fault detection

DOEpatents

Linehan, Daniel J.; Bunch, Stanley L.; Lyster, Carl T.

1995-01-01

A method and circuitry for sampling periodic amplitude modulations in a nonstationary periodic carrier wave to determine frequencies in the amplitude modulations. The method and circuit are described in terms of an improved motor current signature analysis. The method insures that the sampled data set contains an exact whole number of carrier wave cycles by defining the rate at which samples of motor current data are collected. The circuitry insures that a sampled data set containing stationary carrier waves is recreated from the analog motor current signal containing nonstationary carrier waves by conditioning the actual sampling rate to adjust with the frequency variations in the carrier wave. After the sampled data is transformed to the frequency domain via the Discrete Fourier Transform, the frequency distribution in the discrete spectra of those components due to the carrier wave and its harmonics will be minimized so that signals of interest are more easily analyzed.

Design and status of the RF-digitizer integrated circuit

NASA Technical Reports Server (NTRS)

Rayhrer, B.; Lam, B.; Young, L. E.; Srinivasan, J. M.; Thomas, J. B.

1991-01-01

An integrated circuit currently under development samples a bandpass-limited signal at a radio frequency in quadrature and then performs a simple sum-and-dump operation in order to filter and lower the rate of the samples. Downconversion to baseband is carried out by the sampling step itself through the aliasing effect of an appropriately selected subharmonic sampling frequency. Two complete RF digitizer circuits with these functions will be implemented with analog and digital elements on one GaAs substrate. An input signal, with a carrier frequency as high as 8 GHz, can be sampled at a rate as high as 600 Msamples/sec for each quadrature component. The initial version of the chip will sign-sample (1-bit) the input RF signal. The chip will contain a synthesizer to generate a sample frequency that is a selectable integer multiple of an input reference frequency. In addition to the usual advantages of compactness and reliability associated with integrated circuits, the single chip will replace several steps required by standard analog downconversion. Furthermore, when a very high initial sample rate is selected, the presampling analog filters can be given very large bandwidths, thereby greatly reducing phase and delay instabilities typically introduced by such filters, as well as phase and delay variation due to Doppler changes.

Inhalation Frequency Controls Reformatting of Mitral/Tufted Cell Odor Representations in the Olfactory Bulb.

PubMed

Díaz-Quesada, Marta; Youngstrom, Isaac A; Tsuno, Yusuke; Hansen, Kyle R; Economo, Michael N; Wachowiak, Matt

2018-02-28

In mammals, olfactory sensation depends on inhalation, which controls activation of sensory neurons and temporal patterning of central activity. Odor representations by mitral and tufted (MT) cells, the main output from the olfactory bulb (OB), reflect sensory input as well as excitation and inhibition from OB circuits, which may change as sniff frequency increases. To test the impact of sampling frequency on MT cell odor responses, we obtained whole-cell recordings from MT cells in anesthetized male and female mice while varying inhalation frequency via tracheotomy, allowing comparison of inhalation-linked responses across cells. We characterized frequency effects on MT cell responses during inhalation of air and odorants using inhalation pulses and also "playback" of sniffing recorded from awake mice. Inhalation-linked changes in membrane potential were well predicted across frequency from linear convolution of 1 Hz responses; and, as frequency increased, near-identical temporal responses could emerge from depolarizing, hyperpolarizing, or multiphasic MT responses. However, net excitation was not well predicted from 1 Hz responses and varied substantially across MT cells, with some cells increasing and others decreasing in spike rate. As a result, sustained odorant sampling at higher frequencies led to increasing decorrelation of the MT cell population response pattern over time. Bulk activation of sensory inputs by optogenetic stimulation affected MT cells more uniformly across frequency, suggesting that frequency-dependent decorrelation emerges from odor-specific patterns of activity in the OB network. These results suggest that sampling behavior alone can reformat early sensory representations, possibly to optimize sensory perception during repeated sampling. SIGNIFICANCE STATEMENT Olfactory sensation in mammals depends on inhalation, which increases in frequency during active sampling of olfactory stimuli. We asked how inhalation frequency can shape the neural coding of odor information by recording from projection neurons of the olfactory bulb while artificially varying odor sampling frequency in the anesthetized mouse. We found that sampling an odor at higher frequencies led to diverse changes in net responsiveness, as measured by action potential output, that were not predicted from low-frequency responses. These changes led to a reorganization of the pattern of neural activity evoked by a given odorant that occurred preferentially during sustained, high-frequency inhalation. These results point to a novel mechanism for modulating early sensory representations solely as a function of sampling behavior. Copyright © 2018 the authors 0270-6474/18/382189-18$15.00/0.

Cryopreservation of human spermatozoa. I. Effects of holding procedure and seeding on motility, fertilizability, and acrosome reaction.

PubMed

Critser, J K; Huse-Benda, A R; Aaker, D V; Arneson, B W; Ball, G D

1987-04-01

Three experiments were conducted to evaluate effects of holding semen at +5.0 degrees C for 30 minutes or -5.0 degrees C for 10 minutes and ice crystal induction (seeding) on frozen-thawed human spermatozoa. In experiment 1, spermatozoa were frozen, and postthaw motility was evaluated immediately (0 hour) and 24 hours later. At both 0 and 24 hours, nonfrozen control samples had higher motility than all other treatment groups. At 0 hour postthaw, motility was higher in samples held at -5.0 degrees C for 10 minutes with no significant effect of seeding. At 24 hours, samples held at -5.0 degrees C for 10 minutes and seeded, but not samples held at -5.0 degrees C and not seeded, had higher motility than samples held at +5.0 degrees C. In experiment 2, semen samples were frozen, and fertilizability was evaluated in a zona-free hamster egg penetration assay. Seeded samples had a higher frequency of sperm penetration than either nonfrozen or nonseeded samples. In experiment 3, nonfrozen controls and frozen treatment groups were evaluated for the frequency of survival and acrosomal integrity. Seeded samples had higher frequencies of survival and loss of acrosomal integrity than nonseeded samples. All frozen-thawed samples had a lower frequency of survival and a higher frequency of loss of acrosomal integrity than nonfrozen controls. Although altered patterns of fertilizability and acrosomal integrity are induced, collectively these data suggest that incorporating a holding temperature of -5.0 degrees C for 10 minutes and seeding may result in a superior protocol for freezing human spermatozoa.

High-frequency, long-duration water sampling in acid mine drainage studies: a short review of current methods and recent advances in automated water samplers

USGS Publications Warehouse

Chapin, Thomas

2015-01-01

Hand-collected grab samples are the most common water sampling method but using grab sampling to monitor temporally variable aquatic processes such as diel metal cycling or episodic events is rarely feasible or cost-effective. Currently available automated samplers are a proven, widely used technology and typically collect up to 24 samples during a deployment. However, these automated samplers are not well suited for long-term sampling in remote areas or in freezing conditions. There is a critical need for low-cost, long-duration, high-frequency water sampling technology to improve our understanding of the geochemical response to temporally variable processes. This review article will examine recent developments in automated water sampler technology and utilize selected field data from acid mine drainage studies to illustrate the utility of high-frequency, long-duration water sampling.

Frequency-Modulated Continuous Flow Analysis Electrospray Ionization Mass Spectrometry (FM-CFA-ESI-MS) for Sample Multiplexing.

PubMed

Filla, Robert T; Schrell, Adrian M; Coulton, John B; Edwards, James L; Roper, Michael G

2018-02-20

A method for multiplexed sample analysis by mass spectrometry without the need for chemical tagging is presented. In this new method, each sample is pulsed at unique frequencies, mixed, and delivered to the mass spectrometer while maintaining a constant total flow rate. Reconstructed ion currents are then a time-dependent signal consisting of the sum of the ion currents from the various samples. Spectral deconvolution of each reconstructed ion current reveals the identity of each sample, encoded by its unique frequency, and its concentration encoded by the peak height in the frequency domain. This technique is different from other approaches that have been described, which have used modulation techniques to increase the signal-to-noise ratio of a single sample. As proof of concept of this new method, two samples containing up to 9 analytes were multiplexed. The linear dynamic range of the calibration curve was increased with extended acquisition times of the experiment and longer oscillation periods of the samples. Because of the combination of the samples, salt had little effect on the ability of this method to achieve relative quantitation. Continued development of this method is expected to allow for increased numbers of samples that can be multiplexed.

Nanoscale Subsurface Imaging via Resonant Difference-Frequency Atomic Force Ultrasonic Microscopy

NASA Technical Reports Server (NTRS)

Cantrell, Sean A.; Cantrell, John H.; Lilehei, Peter T.

2007-01-01

A novel scanning probe microscope methodology has been developed that employs an ultrasonic wave launched from the bottom of a sample while the cantilever of an atomic force microscope, driven at a frequency differing from the ultrasonic frequency by the fundamental resonance frequency of the cantilever, engages the sample top surface. The nonlinear mixing of the oscillating cantilever and the ultrasonic wave in the region defined by the cantilever tip-sample surface interaction force generates difference-frequency oscillations at the cantilever fundamental resonance. The resonance-enhanced difference-frequency signals are used to create images of embedded nanoscale features.

Sampling western spruce budworm larvae by frequency of occurrence on lower crown branches.

Treesearch

R.R. Mason; R.C. Beckwith

1990-01-01

A sampling method was derived whereby budworm density can be estimated by the frequency of occurrence of larvae over a given threshold number instead of by direct counts on branch samples. The model used for converting frequencies to mean densities is appropriate for nonrandom as well as random distributions and, therefore, is applicable to all population densities of...

Resonant difference-frequency atomic force ultrasonic microscope

NASA Technical Reports Server (NTRS)

Cantrell, John H. (Inventor); Cantrell, Sean A. (Inventor)

2010-01-01

A scanning probe microscope and methodology called resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), employs an ultrasonic wave launched from the bottom of a sample while the cantilever of an atomic force microscope, driven at a frequency differing from the ultrasonic frequency by one of the contact resonance frequencies of the cantilever, engages the sample top surface. The nonlinear mixing of the oscillating cantilever and the ultrasonic wave in the region defined by the cantilever tip-sample surface interaction force generates difference-frequency oscillations at the cantilever contact resonance. The resonance-enhanced difference-frequency signals are used to create images of nanoscale near-surface and subsurface features.

Breaking through the bandwidth barrier in distributed fiber vibration sensing by sub-Nyquist randomized sampling

NASA Astrophysics Data System (ADS)

Zhang, Jingdong; Zhu, Tao; Zheng, Hua; Kuang, Yang; Liu, Min; Huang, Wei

2017-04-01

The round trip time of the light pulse limits the maximum detectable frequency response range of vibration in phase-sensitive optical time domain reflectometry (φ-OTDR). We propose a method to break the frequency response range restriction of φ-OTDR system by modulating the light pulse interval randomly which enables a random sampling for every vibration point in a long sensing fiber. This sub-Nyquist randomized sampling method is suits for detecting sparse-wideband- frequency vibration signals. Up to MHz resonance vibration signal with over dozens of frequency components and 1.153MHz single frequency vibration signal are clearly identified for a sensing range of 9.6km with 10kHz maximum sampling rate.

Simulation Study Using a New Type of Sample Variance

NASA Technical Reports Server (NTRS)

Howe, D. A.; Lainson, K. J.

1996-01-01

We evaluate with simulated data a new type of sample variance for the characterization of frequency stability. The new statistic (referred to as TOTALVAR and its square root TOTALDEV) is a better predictor of long-term frequency variations than the present sample Allan deviation. The statistical model uses the assumption that a time series of phase or frequency differences is wrapped (periodic) with overall frequency difference removed. We find that the variability at long averaging times is reduced considerably for the five models of power-law noise commonly encountered with frequency standards and oscillators.

Hemolysis associated with pneumatic tube system transport for blood samples

PubMed Central

Kara, Hasan; Bayir, Aysegul; Ak, Ahmet; Degirmenci, Selim; Akinci, Murat; Agacayak, Ahmet; Marcil, Emine; Azap, Melih

2014-01-01

Objective: The frequency of hemolysis of blood samples may be increased by transport in a pneumatic tube system. The purpose of this study was to evaluate the effect of pneumatic tube system transport on hemolysis of blood samples. Methods: Blood samples were transported from the emergency department to the hospital laboratory manually by hospital staff (49 patients) or with a pneumatic tube system (53 patients). The hemolysis index and serum chemistry studies were performed on the blood samples and compared between the different methods of transport. Results: The blood samples that were transported by the pneumatic tube system had a greater frequency of hemolysis and greater mean serum potassium and median creatinine, aspartate aminotransferase, and lactate dehydrogenase levels than samples transported manually. Conclusion: Blood samples transported from the emergency department to the hospital laboratory by a pneumatic tube system may have a greater frequency of hemolysis than samples transported manually. This may necessitate repeat phlebotomy and cause a delay in completing the laboratory analysis. PMID:24639830

Elastic Dispersion and Attenuation in Fully Saturated Sandstones: Role of Mineral Content, Porosity, and Pressures

NASA Astrophysics Data System (ADS)

Pimienta, Lucas; Borgomano, Jan V. M.; Fortin, Jérôme; Guéguen, Yves

2017-12-01

Because measuring the frequency dependence of elastic properties in the laboratory is a technical challenge, not enough experimental data exist to test the existing theories. We report measurements of three fluid-saturated sandstones over a broad frequency band: Wilkenson, Berea, and Bentheim sandstones. Those sandstones samples, chosen for their variable porosities and mineral content, are saturated by fluids of varying viscosities. The samples elastic response (Young's modulus and Poisson's ratio) and hydraulic response (fluid flow out of the sample) are measured as a function of frequency. Large dispersion and attenuation phenomena are observed over the investigated frequency range. For all samples, the variation at lowest frequency relates to a large fluid flow directly measured out of the rock samples. These are the cause (i.e., fluid flow) and consequence (i.e., dispersion/attenuation) of the transition between drained and undrained regimes. Consistently, the characteristic frequency correlates with permeability for each sandstone. Beyond this frequency, a second variation is observed for all samples, but the rocks behave differently. For Berea sandstone, an onset of dispersion/attenuation is expected from both Young's modulus and Poisson's ratio at highest frequency. For Bentheim and Wilkenson sandstones, however, only Young's modulus shows dispersion/attenuation phenomena. For Wilkenson sandstone, the viscoelastic-like dispersion/attenuation response is interpreted as squirt flow. For Bentheim sandstone, the second effect does not fully follow such response, which could be due to a lower accuracy in the measured attenuation or to the occurence of another physical effect in this rock sample.

Window of visibility - A psychophysical theory of fidelity in time-sampled visual motion displays

NASA Technical Reports Server (NTRS)

Watson, A. B.; Ahumada, A. J., Jr.; Farrell, J. E.

1986-01-01

A film of an object in motion presents on the screen a sequence of static views, while the human observer sees the object moving smoothly across the screen. Questions related to the perceptual identity of continuous and stroboscopic displays are examined. Time-sampled moving images are considered along with the contrast distribution of continuous motion, the contrast distribution of stroboscopic motion, the frequency spectrum of continuous motion, the frequency spectrum of stroboscopic motion, the approximation of the limits of human visual sensitivity to spatial and temporal frequencies by a window of visibility, the critical sampling frequency, the contrast distribution of staircase motion and the frequency spectrum of this motion, and the spatial dependence of the critical sampling frequency. Attention is given to apparent motion, models of motion, image recording, and computer-generated imagery.

Two models of the sound-signal frequency dependence on the animal body size as exemplified by the ground squirrels of Eurasia (mammalia, rodentia).

PubMed

Nikol'skii, A A

2017-11-01

Dependence of the sound-signal frequency on the animal body length was studied in 14 ground squirrel species (genus Spermophilus) of Eurasia. Regression analysis of the total sample yielded a low determination coefficient (R 2 = 26%), because the total sample proved to be heterogeneous in terms of signal frequency within the dimension classes of animals. When the total sample was divided into two groups according to signal frequency, two statistically significant models (regression equations) were obtained in which signal frequency depended on the body size at high determination coefficients (R 2 = 73 and 94% versus 26% for the total sample). Thus, the problem of correlation between animal body size and the frequency of their vocal signals does not have a unique solution.

Acoustic resonance frequency locked photoacoustic spectrometer

DOEpatents

Pilgrim, Jeffrey S.; Bomse, David S.; Silver, Joel A.

2003-09-09

A photoacoustic spectroscopy method and apparatus for maintaining an acoustic source frequency on a sample cell resonance frequency comprising: providing an acoustic source to the sample cell, the acoustic source having a source frequency; repeatedly and continuously sweeping the source frequency across the resonance frequency at a sweep rate; and employing an odd-harmonic of the source frequency sweep rate to maintain the source frequency sweep centered on the resonance frequency.

Method for obtaining chromosome painting probes

DOEpatents

Lucas, Joe N.

2000-01-01

A method is provided for determining a clastogenic signature of a sample of chromosomes by quantifying a frequency of a first type of chromosome aberration present in the sample; quantifying a frequency of a second, different type of chromosome aberration present in the sample; and comparing the frequency of the first type of chromosome aberration to the frequency of the second type of chromosome aberration. A method is also provided for using that clastogenic signature to identify a clastogenic agent or dosage to which the cells were exposed.

Front end for GPS receivers

NASA Technical Reports Server (NTRS)

Thomas, Jr., Jess Brooks (Inventor)

1999-01-01

The front end in GPS receivers has the functions of amplifying, down-converting, filtering and sampling the received signals. In the preferred embodiment, only two operations, A/D conversion and a sum, bring the signal from RF to filtered quadrature baseband samples. After amplification and filtering at RF, the L1 and L2 signals are each sampled at RF at a high selected subharmonic rate. The subharmonic sample rates are approximately 900 MHz for L1 and 982 MHz for L2. With the selected subharmonic sampling, the A/D conversion effectively down-converts the signal from RF to quadrature components at baseband. The resulting sample streams for L1 and L2 are each reduced to a lower rate with a digital filter, which becomes a straight sum in the simplest embodiment. The frequency subsystem can be very simple, only requiring the generation of a single reference frequency (e.g. 20.46 MHz minus a small offset) and the simple multiplication of this reference up to the subharmonic sample rates for L1 and L2. The small offset in the reference frequency serves the dual purpose of providing an advantageous offset in the down-converted carrier frequency and in the final baseband sample rate.

Confidence intervals for population allele frequencies: the general case of sampling from a finite diploid population of any size.

PubMed

Fung, Tak; Keenan, Kevin

2014-01-01

The estimation of population allele frequencies using sample data forms a central component of studies in population genetics. These estimates can be used to test hypotheses on the evolutionary processes governing changes in genetic variation among populations. However, existing studies frequently do not account for sampling uncertainty in these estimates, thus compromising their utility. Incorporation of this uncertainty has been hindered by the lack of a method for constructing confidence intervals containing the population allele frequencies, for the general case of sampling from a finite diploid population of any size. In this study, we address this important knowledge gap by presenting a rigorous mathematical method to construct such confidence intervals. For a range of scenarios, the method is used to demonstrate that for a particular allele, in order to obtain accurate estimates within 0.05 of the population allele frequency with high probability (> or = 95%), a sample size of > 30 is often required. This analysis is augmented by an application of the method to empirical sample allele frequency data for two populations of the checkerspot butterfly (Melitaea cinxia L.), occupying meadows in Finland. For each population, the method is used to derive > or = 98.3% confidence intervals for the population frequencies of three alleles. These intervals are then used to construct two joint > or = 95% confidence regions, one for the set of three frequencies for each population. These regions are then used to derive a > or = 95%% confidence interval for Jost's D, a measure of genetic differentiation between the two populations. Overall, the results demonstrate the practical utility of the method with respect to informing sampling design and accounting for sampling uncertainty in studies of population genetics, important for scientific hypothesis-testing and also for risk-based natural resource management.

Arcobacter Isolation from Minced Beef Samples in Costa Rica.

PubMed

Córdoba-Calderón, Oscar; Redondo-Solano, Mauricio; Castro-Arias, Eduardo; Arias-EchandI, María Laura

2017-04-03

The presence of Arcobacter spp. in minced meat (including beef) samples has been well documented in different countries, with varying frequencies. Nevertheless, the only Latin American country reporting this bacterium in minced beef samples is Mexico, with a 28.8% frequency in 2003. Previous studies in Costa Rica have demonstrated the presence of Arcobacter species in samples taken from the poultry production chain, but still there are no studies performed in bovine meat. The aim of this study was to determine the frequency of this bacterium in 120 samples of minced beef acquired from the Central Valley region of Costa Rica and to describe the antibiotic sensitivity pattern of the isolates obtained. A total of 75 different Arcobacter strains were isolated from minced beef samples, for a final frequency of 48.3%. After species PCR identification, the strains were classified as A. butzleri (37.3%), A. cibarius (14.7%), A. thereius (12%), and Arcobacter spp. (36%). All samples were sensitive to gentamicin but were resistant to ampicillin, levofloxacin, nalidixic acid, and ciprofloxacin. The results obtained in this study show that the frequency of isolation of Arcobacter in minced beef samples is high and that there is a high resistance rate for antibiotics in common use. This suggests that Arcobacter represents a health risk for Costa Rica and that control measures should be developed to decrease its potential impact.

Method and apparatus configured for identification of a material

DOEpatents

Slater, John M.; Crawford, Thomas M.

2000-01-01

The present invention includes an apparatus configured for identification of a material, and methods of identifying a material. One embodiment of the invention provides an apparatus including a first region configured to receive a first sample, the first region being configured to output a first spectrum corresponding to the first sample and responsive to exposure of the first sample to radiation; a modulator configured to modulate the first spectrum according to a first frequency; a second region configured to receive a second sample, the second region being configured to output a second spectrum corresponding to the second sample and responsive to exposure of the second sample to the modulated first spectrum; and a detector configured to detect the second spectrum having a second frequency greater than the first frequency.

Method and apparatus for generating motor current spectra to enhance motor system fault detection

DOEpatents

Linehan, D.J.; Bunch, S.L.; Lyster, C.T.

1995-10-24

A method and circuitry are disclosed for sampling periodic amplitude modulations in a nonstationary periodic carrier wave to determine frequencies in the amplitude modulations. The method and circuit are described in terms of an improved motor current signature analysis. The method insures that the sampled data set contains an exact whole number of carrier wave cycles by defining the rate at which samples of motor current data are collected. The circuitry insures that a sampled data set containing stationary carrier waves is recreated from the analog motor current signal containing nonstationary carrier waves by conditioning the actual sampling rate to adjust with the frequency variations in the carrier wave. After the sampled data is transformed to the frequency domain via the Discrete Fourier Transform, the frequency distribution in the discrete spectra of those components due to the carrier wave and its harmonics will be minimized so that signals of interest are more easily analyzed. 29 figs.

Electrical properties of Apollo 17 rock and soil samples and a summary of the electrical properties of lunar material at 450 MHz frequency

NASA Technical Reports Server (NTRS)

Gold, T.; Bilson, E.; Baron, R. L.

1976-01-01

The dielectric constant and the voltage absorption length was measured for four Apollo 17 soil samples (73241, 74220, 75061, 76501) and for two Apollo 17 rock samples (76315 and 79135) at 450 MHz frequency. The dielectric constant and absorption length measurements made on the lunar samples are reviewed and related to the transition element concentration in these samples. The significance of the laboratory measurements for radar observations is discussed.

Comparison of SHOX and associated elements duplications distribution between patients (Lėri-Weill dyschondrosteosis/idiopathic short stature) and population sample.

PubMed

Hirschfeldova, Katerina; Solc, Roman

2017-09-05

The effect of heterozygous duplications of SHOX and associated elements on Lėri-Weill dyschondrosteosis (LWD) and idiopathic short stature (ISS) development is less distinct when compared to reciprocal deletions. The aim of our study was to compare frequency and distribution of duplications within SHOX and associated elements between population sample and LWD (ISS) patients. A preliminary analysis conducted on Czech population sample of 250 individuals compared to our previously reported sample of 352 ISS/LWD Czech patients indicated that rather than the difference in frequency of duplications it is the difference in their distribution. Particularly, there was an increased frequency of duplications residing to the CNE-9 enhancer in our LWD/ISS sample. To see whether the obtained data are consistent across published studies we made a literature survey to get published cases with SHOX or associated elements duplication and formed the merged LWD, the merged ISS, and the merged population samples. Relative frequency of particular region duplication in each of those merged samples were calculated. There was a significant difference in the relative frequency of CNE-9 enhancer duplications (11 vs. 3) and complete SHOX (exon1-6b) duplications (4 vs. 24) (p-value 0.0139 and p-value 0.000014, respectively) between the merged LWD sample and the merged population sample. We thus propose that partial SHOX duplications and small duplications encompassing CNE-9 enhancer could be highly penetrant alleles associated with ISS and LWD development. Copyright © 2017 Elsevier B.V. All rights reserved.

Automatic frequency control for FM transmitter

NASA Technical Reports Server (NTRS)

Honnell, M. A. (Inventor)

1974-01-01

An automatic frequency control circuit for an FM television transmitter is described. The frequency of the transmitter is sampled during what is termed the back porch portion of the horizontal synchronizing pulse which occurs during the retrace interval, the frequency sample compared with the frequency of a reference oscillator, and a correction applied to the frequency of the transmitter during this portion of the retrace interval.

Journal: A Review of Some Tracer-Test Design Equations for Tracer-Mass Estimation and Sample Collection Frequency

EPA Science Inventory

Determination of necessary tracer mass, initial sample-collection time, and subsequent sample-collection frequency are the three most difficult aspects to estimate for a proposed tracer test prior to conducting the tracer test. To facilitate tracer-mass estimation, 33 mass-estima...

Rapid method for measuring clastogenic fingerprints using fluorescence in situ hybridization

DOEpatents

Lucas, Joe N.

2000-01-01

A method is provided for determining a clastogenic signature of a sample of chromosomes by quantifying a frequency of a first type of chromosome aberration present in the sample; quantifying a frequency of a second, different type of chromosome aberration present in the sample; and comparing the frequency of the first type of chromosome aberration to the frequency of the second type of chromosome aberration. A method is also provided for using that clastogenic signature to identify a clastogenic agent or dosage to which the cells were exposed.

Method for detecting a pericentric inversion in a chromosome

DOEpatents

Lucas, Joe N.

2000-01-01

A method is provided for determining a clastogenic signature of a sample of chromosomes by quantifying a frequency of a first type of chromosome aberration present in the sample; quantifying a frequency of a second, different type of chromosome aberration present in the sample; and comparing the frequency of the first type of chromosome aberration to the frequency of the second type of chromosome aberration. A method is also provided for using that clastogenic signature to identify a clastogenic agent or dosage to which the cells were exposed.

A role for high frequency hydrochemical sampling in long term ecosystem studies

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.; Shanley, J. B.; Boyer, E. W.; Kendall, C.

2007-12-01

Monitoring of surface waters for major chemical constituents is needed to assess long-term trends and responses to ecological disturbance. However, the typical fixed-interval (weekly, monthly, or quarterly) sampling schemes of most long-term ecosystem studies may not capture the full range of stream chemical variation and do not always provide enough information to discern the landscape processes that control surface water chemistry and solute loadings. To expand upon traditional hydrochemical monitoring, we collected high frequency event-based surface water samples at an upland, forested basin of the Sleepers River Research Watershed (Vermont, USA), one of five intensively studied sites in the Water, Energy, and Biogeochemical Budgets (WEBB) program of the US Geological Survey. We present several examples that highlight the importance of linking long-term weekly data with intensive, high frequency sampling. We used end-member mixing analysis and isotopic approaches to trace sources of stream nutrients (e.g. nitrate, dissolved organic carbon) and quantified how atmospheric pollutants (e.g. nitrogen, sulfate, and mercury) affect stream chemistry. High frequency sampling generates large numbers of samples and is both labor and resource intensive but yields insights into ecosystem functions that are not readily discerned from less-frequent sampling. As the ecological community contemplates the scope and foci of environmental observatories as benchmarks for deciphering the effects of natural and anthropogenic change, incorporating high frequency hydrochemical sampling will further our understanding of ecosystem functions across a range of ecosystem types and disturbance effects.

40 CFR 141.803 - Coliform sampling.

Code of Federal Regulations, 2012 CFR

2012-07-01

... aircraft water system, the sampling frequency must be determined by the disinfection and flushing frequency... disinfection and flushing frequency recommended by the aircraft water system manufacturer, when available. Where the aircraft water system manufacturer does not specify a recommended routine disinfection and...

Passive ultrasonics using sub-Nyquist sampling of high-frequency thermal-mechanical noise.

PubMed

Sabra, Karim G; Romberg, Justin; Lani, Shane; Degertekin, F Levent

2014-06-01

Monolithic integration of capacitive micromachined ultrasonic transducer arrays with low noise complementary metal oxide semiconductor electronics minimizes interconnect parasitics thus allowing the measurement of thermal-mechanical (TM) noise. This enables passive ultrasonics based on cross-correlations of diffuse TM noise to extract coherent ultrasonic waves propagating between receivers. However, synchronous recording of high-frequency TM noise puts stringent requirements on the analog to digital converter's sampling rate. To alleviate this restriction, high-frequency TM noise cross-correlations (12-25 MHz) were estimated instead using compressed measurements of TM noise which could be digitized at a sampling frequency lower than the Nyquist frequency.

Phase coded, micro-power impulse radar motion sensor

DOEpatents

McEwan, Thomas E.

1996-01-01

A motion sensing, micro-power impulse radar MIR impresses on the transmitted signal, or the received pulse timing signal, one or more frequencies lower than the pulse repetition frequency, that become intermediate frequencies in a "IF homodyne" receiver. Thus, many advantages of classical RF receivers can be thereby be realized with ultra-wide band radar. The sensor includes a transmitter which transmits a sequence of electromagnetic pulses in response to a transmit timing signal at a nominal pulse repetition frequency. A receiver samples echoes of the sequence of electromagnetic pulses from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay at an intermediate frequency, causing the receiver to sample the echoes such that the time between transmissions of pulses in the sequence and samples by the receiver is modulated at the intermediate frequency. Modulation may be executed by modulating the pulse repetition frequency which drives the transmitter, by modulating the delay circuitry which controls the relative timing of the sample strobe, or by modulating amplitude of the transmitted pulses. The electromagnetic pulses will have a nominal center frequency related to pulse width, and the first relative delay and the second relative delay between which the timing signals are modulated, differ by less than the nominal pulse width, and preferably by about one-quarter wavelength at the nominal center frequency of the transmitted pulses.

Phase coded, micro-power impulse radar motion sensor

DOEpatents

McEwan, T.E.

1996-05-21

A motion sensing, micro-power impulse radar MIR impresses on the transmitted signal, or the received pulse timing signal, one or more frequencies lower than the pulse repetition frequency, that become intermediate frequencies in a ``IF homodyne`` receiver. Thus, many advantages of classical RF receivers can be thereby be realized with ultra-wide band radar. The sensor includes a transmitter which transmits a sequence of electromagnetic pulses in response to a transmit timing signal at a nominal pulse repetition frequency. A receiver samples echoes of the sequence of electromagnetic pulses from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay at an intermediate frequency, causing the receiver to sample the echoes such that the time between transmissions of pulses in the sequence and samples by the receiver is modulated at the intermediate frequency. Modulation may be executed by modulating the pulse repetition frequency which drives the transmitter, by modulating the delay circuitry which controls the relative timing of the sample strobe, or by modulating amplitude of the transmitted pulses. The electromagnetic pulses will have a nominal center frequency related to pulse width, and the first relative delay and the second relative delay between which the timing signals are modulated, differ by less than the nominal pulse width, and preferably by about one-quarter wavelength at the nominal center frequency of the transmitted pulses. 5 figs.

General solution of undersampling frequency conversion and its optimization for parallel photodisplacement imaging.

PubMed

Nakata, Toshihiko; Ninomiya, Takanori

2006-10-10

A general solution of undersampling frequency conversion and its optimization for parallel photodisplacement imaging is presented. Phase-modulated heterodyne interference light generated by a linear region of periodic displacement is captured by a charge-coupled device image sensor, in which the interference light is sampled at a sampling rate lower than the Nyquist frequency. The frequencies of the components of the light, such as the sideband and carrier (which include photodisplacement and topography information, respectively), are downconverted and sampled simultaneously based on the integration and sampling effects of the sensor. A general solution of frequency and amplitude in this downconversion is derived by Fourier analysis of the sampling procedure. The optimal frequency condition for the heterodyne beat signal, modulation signal, and sensor gate pulse is derived such that undesirable components are eliminated and each information component is converted into an orthogonal function, allowing each to be discretely reproduced from the Fourier coefficients. The optimal frequency parameters that maximize the sideband-to-carrier amplitude ratio are determined, theoretically demonstrating its high selectivity over 80 dB. Preliminary experiments demonstrate that this technique is capable of simultaneous imaging of reflectivity, topography, and photodisplacement for the detection of subsurface lattice defects at a speed corresponding to an acquisition time of only 0.26 s per 256 x 256 pixel area.

Crying and Depression Among Older Adults.

ERIC Educational Resources Information Center

Hastrup, Janice L.; And Others

1986-01-01

Self-reports of frequency of crying episodes are described for two nonclinical samples of younger and older adult men and women. Comparison of samples revealed no evidence for either a decreased or increased frequency of crying among the older sample. Crying episodes function as an adaptive coping response to and should not be automatically…

Microwave resonances in dielectric samples probed in Corbino geometry: simulation and experiment.

PubMed

Felger, M Maximilian; Dressel, Martin; Scheffler, Marc

2013-11-01

The Corbino approach, where the sample of interest terminates a coaxial cable, is a well-established method for microwave spectroscopy. If the sample is dielectric and if the probe geometry basically forms a conductive cavity, this combination can sustain well-defined microwave resonances that are detrimental for broadband measurements. Here, we present detailed simulations and measurements to investigate the resonance frequencies as a function of sample and probe size and of sample permittivity. This allows a quantitative optimization to increase the frequency of the lowest-lying resonance.

Planning of a Demonstration Project for Main Channel Disposal of Dredged Material.

DTIC Science & Technology

1980-07-01

S imon Eng lieerlng Reserch Center Y.. C Colorado State University Fort C.Ilin, Colredo- 0 -d - *-¢ i ,.., . . . FOREWORD This study was...program which identifies data needs, equipment needs and methods for collection and analyses of samples , sampling frequencies and spacing and cost...4.3.1 Data Needs .. ........ ....... 65 4.3.2 Equipment Needs and Methods for Collection and Analyses of Samples . 5 4.3.3 Sampling Frequencies and

Pulsed phase locked loop strain monitor

NASA Technical Reports Server (NTRS)

Froggatt, Mark E. (Inventor)

1995-01-01

A pulse phase locked loop system according to the present invention is described. A frequency generator such as a voltage controlled oscillator (VCO) generates an output signal and a reference signal having a frequency equal to that of the output signal. A transmitting gate gates the output frequency signal and this gated signal drives a transmitting transducer which transmits an acoustic wave through a material. A sample/hold samples a signal indicative of the transmitted wave which is received by a receiving transducer. Divide-by-n counters control these gating and sampling functions in response to the reference signal of the frequency generator. Specifically, the output signal is gated at a rate of F/h, wherein F is the frequency of the output signal and h is an integer; and the received signal is sampled at a delay of F/n wherein n is an integer.

Fiber-based polarization-sensitive Mueller matrix optical coherence tomography with continuous source polarization modulation.

PubMed

Jiao, Shuliang; Todorović, Milos; Stoica, George; Wang, Lihong V

2005-09-10

We report on a new configuration of fiber-based polarization-sensitive Mueller matrix optical coherence tomography that permits the acquisition of the round-trip Jones matrix of a biological sample using only one light source and a single depth scan. In this new configuration, a polarization modulator is used in the source arm to continuously modulate the incident polarization state for both the reference and the sample arms. The Jones matrix of the sample can be calculated from the two frequency terms in the two detection channels. The first term is modulated by the carrier frequency, which is determined by the longitudinal scanning mechanism, whereas the other term is modulated by the beat frequency between the carrier frequency and the second harmonic of the modulation frequency of the polarization modulator. One important feature of this system is that, for the first time to our knowledge, the Jones matrix of the sample can be calculated with a single detection channel and a single measurement when diattenuation is negligible. The system was successfully tested by imaging both standard polarization elements and biological samples.

Visual sensitivity to spatially sampled modulation in human observers

NASA Technical Reports Server (NTRS)

Mulligan, Jeffrey B.; Macleod, Donald I. A.

1991-01-01

Thresholds were measured for detecting spatial luminance modulation in regular lattices of visually discrete dots. Thresholds for modulation of a lattice are generally higher than the corresponding threshold for modulation of a continuous field, and the size of the threshold elevation, which depends on the spacing of the lattice elements, can be as large as a one log unit. The largest threshold elevations are seen when the sample spacing is 12 min arc or greater. Theories based on response compression cannot explain the further observation that the threshold elevations due to spatial sampling are also dependent on modulation frequency: the greatest elevations occur with higher modulation frequencies. The idea that this is due to masking of the modulation frequency by the spatial frequencies in the sampling lattice is considered.

Uncertainty of streamwater solute fluxes in five contrasting headwater catchments including model uncertainty and natural variability (Invited)

NASA Astrophysics Data System (ADS)

Aulenbach, B. T.; Burns, D. A.; Shanley, J. B.; Yanai, R. D.; Bae, K.; Wild, A.; Yang, Y.; Dong, Y.

2013-12-01

There are many sources of uncertainty in estimates of streamwater solute flux. Flux is the product of discharge and concentration (summed over time), each of which has measurement uncertainty of its own. Discharge can be measured almost continuously, but concentrations are usually determined from discrete samples, which increases uncertainty dependent on sampling frequency and how concentrations are assigned for the periods between samples. Gaps between samples can be estimated by linear interpolation or by models that that use the relations between concentration and continuously measured or known variables such as discharge, season, temperature, and time. For this project, developed in cooperation with QUEST (Quantifying Uncertainty in Ecosystem Studies), we evaluated uncertainty for three flux estimation methods and three different sampling frequencies (monthly, weekly, and weekly plus event). The constituents investigated were dissolved NO3, Si, SO4, and dissolved organic carbon (DOC), solutes whose concentration dynamics exhibit strongly contrasting behavior. The evaluation was completed for a 10-year period at five small, forested watersheds in Georgia, New Hampshire, New York, Puerto Rico, and Vermont. Concentration regression models were developed for each solute at each of the three sampling frequencies for all five watersheds. Fluxes were then calculated using (1) a linear interpolation approach, (2) a regression-model method, and (3) the composite method - which combines the regression-model method for estimating concentrations and the linear interpolation method for correcting model residuals to the observed sample concentrations. We considered the best estimates of flux to be derived using the composite method at the highest sampling frequencies. We also evaluated the importance of sampling frequency and estimation method on flux estimate uncertainty; flux uncertainty was dependent on the variability characteristics of each solute and varied for different reporting periods (e.g. 10-year, study period vs. annually vs. monthly). The usefulness of the two regression model based flux estimation approaches was dependent upon the amount of variance in concentrations the regression models could explain. Our results can guide the development of optimal sampling strategies by weighing sampling frequency with improvements in uncertainty in stream flux estimates for solutes with particular characteristics of variability. The appropriate flux estimation method is dependent on a combination of sampling frequency and the strength of concentration regression models. Sites: Biscuit Brook (Frost Valley, NY), Hubbard Brook Experimental Forest and LTER (West Thornton, NH), Luquillo Experimental Forest and LTER (Luquillo, Puerto Rico), Panola Mountain (Stockbridge, GA), Sleepers River Research Watershed (Danville, VT)

Baseline-dependent sampling and windowing for radio interferometry: data compression, field-of-interest shaping, and outer field suppression

NASA Astrophysics Data System (ADS)

Atemkeng, M.; Smirnov, O.; Tasse, C.; Foster, G.; Keimpema, A.; Paragi, Z.; Jonas, J.

2018-07-01

Traditional radio interferometric correlators produce regular-gridded samples of the true uv-distribution by averaging the signal over constant, discrete time-frequency intervals. This regular sampling and averaging then translate to be irregular-gridded samples in the uv-space, and results in a baseline-length-dependent loss of amplitude and phase coherence, which is dependent on the distance from the image phase centre. The effect is often referred to as `decorrelation' in the uv-space, which is equivalent in the source domain to `smearing'. This work discusses and implements a regular-gridded sampling scheme in the uv-space (baseline-dependent sampling) and windowing that allow for data compression, field-of-interest shaping, and source suppression. The baseline-dependent sampling requires irregular-gridded sampling in the time-frequency space, i.e. the time-frequency interval becomes baseline dependent. Analytic models and simulations are used to show that decorrelation remains constant across all the baselines when applying baseline-dependent sampling and windowing. Simulations using MeerKAT telescope and the European Very Long Baseline Interferometry Network show that both data compression, field-of-interest shaping, and outer field-of-interest suppression are achieved.

Model-based frequency response characterization of a digital-image analysis system for epifluorescence microscopy

NASA Technical Reports Server (NTRS)

Hazra, Rajeeb; Viles, Charles L.; Park, Stephen K.; Reichenbach, Stephen E.; Sieracki, Michael E.

1992-01-01

Consideration is given to a model-based method for estimating the spatial frequency response of a digital-imaging system (e.g., a CCD camera) that is modeled as a linear, shift-invariant image acquisition subsystem that is cascaded with a linear, shift-variant sampling subsystem. The method characterizes the 2D frequency response of the image acquisition subsystem to beyond the Nyquist frequency by accounting explicitly for insufficient sampling and the sample-scene phase. Results for simulated systems and a real CCD-based epifluorescence microscopy system are presented to demonstrate the accuracy of the method.

Acoustic resonance phase locked photoacoustic spectrometer

DOEpatents

Pilgrim, Jeffrey S.; Bomse, David S.; Silver, Joel A.

2003-08-19

A photoacoustic spectroscopy method and apparatus for maintaining an acoustic source frequency on a sample cell resonance frequency comprising: providing an acoustic source to the sample cell to generate a photoacoustic signal, the acoustic source having a source frequency; continuously measuring detection phase of the photoacoustic signal with respect to source frequency or a harmonic thereof; and employing the measured detection phase to provide magnitude and direction for correcting the source frequency to the resonance frequency.

Sexual behavior predictors of satisfaction in a Chinese sample.

PubMed

Tao, Peng; Brody, Stuart

2011-02-01

Previous multivariate research in Europe found that sexual satisfaction was associated directly with frequency of penile-vaginal intercourse (PVI) but inversely with masturbation and some aspects of non-PVI partnered sex. To examine the associations of sexual satisfaction in a sample from the People's Republic of China, including not only frequencies of various sexual behaviors, but also frequencies of orgasm. Chinese industrial workers (N=158, age over 24 years) completed the sexual satisfaction scale of the Multidimensional Sexuality Questionnaire (MSQ) and a short form of the Marlowe-Crowne social desirability scale, and provided details of the one month frequencies of engaging in, and having an orgasm from, PVI, masturbation, and non-PVI partnered sex. Multiple regression prediction of sexual satisfaction from age, social desirability responding, and in separate analyses, frequencies of the sexual behaviors or the corresponding orgasm frequencies. For men and women, sexual satisfaction was associated with frequency of PVI and of PVI orgasm (the latter for women only), but not other sexual behavior or orgasm frequency. Similar results were obtained for the MSQ satisfaction scale and for a single satisfaction item. Despite cultural differences (and our smaller, less diverse sample), the positive prediction of satisfaction from only PVI (and in our sample of women, PVI orgasm) frequency-but not other sexual activities-was similar to that in a Swedish sample. Future research might also examine possible occasional avoidance of ejaculation by some Chinese men. © 2010 International Society for Sexual Medicine.

EMR Gage Would Measure Coal Thickness Accurately

NASA Technical Reports Server (NTRS)

King, J. D.; Rollwitz, W. L.

1982-01-01

Laboratory tests indicate electron magnetic resonance (EMR) would be effective in measuring thickness of coal overlying rock substrate. In prototype dual-frequency EMR system, Sample is irradiated by two radio frequencies. Signals are mixed, producing sum and difference output frequencies that are detected by receiver. Magnetic field is varied to scan resonant spot through sample. In system designed for field use, electromagnet is U-shaped, so that sample can be adjacent to, rather than inside the probe. Same coil is used for transmitting and receiving.

Time-Frequency Based Instantaneous Frequency Estimation of Sparse Signals from an Incomplete Set of Samples

DTIC Science & Technology

2014-06-17

100 0 2 4 Wigner distribution 0 50 100 0 0.5 1 Auto-correlation function 0 50 100 0 2 4 L- Wigner distribution 0 50 100 0 0.5 1 Auto-correlation function ...bilinear or higher order autocorrelation functions will increase the number of missing samples, the analysis shows that accurate instantaneous...frequency estimation can be achieved even if we deal with only few samples, as long as the auto-correlation function is properly chosen to coincide with

On Frequency Offset Estimation Using the iNET Preamble in Frequency Selective Fading Channels

DTIC Science & Technology

2014-03-01

ASM fields; (bottom) the relationship between the indexes of the received samples r(n), the signal samples s(n), the preamble samples p (n) and the short...frequency offset estimators for SOQPSK-TG equipped with the iNET preamble and operating in ISI channels. Four of the five estimators exam - ined here are...sync marker ( ASM ), and data bits (an LDPC codeword). The availability of a preamble introduces the possibility of data-aided synchro- nization in

Non-Wovens as Sound Reducers

NASA Astrophysics Data System (ADS)

Belakova, D.; Seile, A.; Kukle, S.; Plamus, T.

2018-04-01

Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

Using high-frequency sampling to detect effects of atmospheric pollutants on stream chemistry

Treesearch

Stephen D. Sebestyen; James B. Shanley; Elizabeth W. Boyer

2009-01-01

We combined information from long-term (weekly over many years) and short-term (high-frequency during rainfall and snowmelt events) stream water sampling efforts to understand how atmospheric deposition affects stream chemistry. Water samples were collected at the Sleepers River Research Watershed, VT, a temperate upland forest site that receives elevated atmospheric...

Low frequency noise elimination technique for 24-bit Σ-Δ data acquisition systems.

PubMed

Qu, Shao-Bo; Robert, Olivier; Lognonné, Philippe; Zhou, Ze-Bing; Yang, Shan-Qing

2015-03-01

Low frequency 1/f noise is one of the key limiting factors of high precision measurement instruments. In this paper, digital correlated double sampling is implemented to reduce the offset and low frequency 1/f noise of a data acquisition system with 24-bit sigma delta (Σ-Δ) analog to digital converter (ADC). The input voltage is modulated by cross-coupled switches, which are synchronized to the sampling clock, and converted into digital signal by ADC. By using a proper switch frequency, the unwanted parasitic signal frequencies generated by the switches are avoided. The noise elimination processing is made through the principle of digital correlated double sampling, which is equivalent to a time shifted subtraction for the sampled voltage. The low frequency 1/f noise spectrum density of the data acquisition system is reduced to be flat down to the measurement frequency lower limit, which is about 0.0001 Hz in this paper. The noise spectrum density is eliminated by more than 60 dB at 0.0001 Hz, with a residual noise floor of (9 ± 2) nV/Hz(1/2) which is limited by the intrinsic white noise floor of the ADC above its corner frequency.

Treatment of atomic and molecular line blanketing by opacity sampling

NASA Technical Reports Server (NTRS)

Johnson, H. R.; Krupp, B. M.

1976-01-01

A sampling technique for treating the radiative opacity of large numbers of atomic and molecular lines in cool stellar atmospheres is subjected to several tests. In this opacity sampling (OS) technique, the global opacity is sampled at only a selected set of frequencies, and at each of these frequencies the total monochromatic opacity is obtained by summing the contribution of every relevant atomic and molecular line. In accord with previous results, we find that the structure of atmospheric models is accurately fixed by the use of 1000 frequency points, and 100 frequency points are adequate for many purposes. The effects of atomic and molecular lines are separately studied. A test model computed using the OS method agrees very well with a model having identical atmospheric parameters, but computed with the giant line (opacity distribution function) method.

Study of dielectric phenomenon for P3HT: PCBM blend

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Kumar, Manoj; Rathi, Sonika; Singh, Amarjeet

2017-05-01

In this present work we prepared the film sample of blend (P3HT (poly (3-hexylthiophene-2, 5-diyl)): PCBM ([6,6]-phenyl C61-butyric acid methyl ester)), P3HT and PCBM solution on ITO substrate by drop cast method. Capacitance and tangent loss (tan δ) were measured and dielectric constants έ and dielectric loss ɛ″ were deduced from them as function frequency at room temperature. Blend samples show strong frequency dependence as compared to pristine P3HT and pristine PCBM sample. The high dielectric constant in blend films at low frequency was attributed to characteristic slow relaxation process in polymers along with polarization of isolated grains in the blend sample.

Comparisons of discrete and integrative sampling accuracy in estimating pulsed aquatic exposures.

PubMed

Morrison, Shane A; Luttbeg, Barney; Belden, Jason B

2016-11-01

Most current-use pesticides have short half-lives in the water column and thus the most relevant exposure scenarios for many aquatic organisms are pulsed exposures. Quantifying exposure using discrete water samples may not be accurate as few studies are able to sample frequently enough to accurately determine time-weighted average (TWA) concentrations of short aquatic exposures. Integrative sampling methods that continuously sample freely dissolved contaminants over time intervals (such as integrative passive samplers) have been demonstrated to be a promising measurement technique. We conducted several modeling scenarios to test the assumption that integrative methods may require many less samples for accurate estimation of peak 96-h TWA concentrations. We compared the accuracies of discrete point samples and integrative samples while varying sampling frequencies and a range of contaminant water half-lives (t 50  = 0.5, 2, and 8 d). Differences the predictive accuracy of discrete point samples and integrative samples were greatest at low sampling frequencies. For example, when the half-life was 0.5 d, discrete point samples required 7 sampling events to ensure median values > 50% and no sampling events reporting highly inaccurate results (defined as < 10% of the true 96-h TWA). Across all water half-lives investigated, integrative sampling only required two samples to prevent highly inaccurate results and measurements resulting in median values > 50% of the true concentration. Regardless, the need for integrative sampling diminished as water half-life increased. For an 8-d water half-life, two discrete samples produced accurate estimates and median values greater than those obtained for two integrative samples. Overall, integrative methods are the more accurate method for monitoring contaminants with short water half-lives due to reduced frequency of extreme values, especially with uncertainties around the timing of pulsed events. However, the acceptability of discrete sampling methods for providing accurate concentration measurements increases with increasing aquatic half-lives. Copyright © 2016 Elsevier Ltd. All rights reserved.

Determination of the influence of dispersion pattern of pesticide-resistant individuals on the reliability of resistance estimates using different sampling plans.

PubMed

Shah, R; Worner, S P; Chapman, R B

2012-10-01

Pesticide resistance monitoring includes resistance detection and subsequent documentation/ measurement. Resistance detection would require at least one (≥1) resistant individual(s) to be present in a sample to initiate management strategies. Resistance documentation, on the other hand, would attempt to get an estimate of the entire population (≥90%) of the resistant individuals. A computer simulation model was used to compare the efficiency of simple random and systematic sampling plans to detect resistant individuals and to document their frequencies when the resistant individuals were randomly or patchily distributed. A patchy dispersion pattern of resistant individuals influenced the sampling efficiency of systematic sampling plans while the efficiency of random sampling was independent of such patchiness. When resistant individuals were randomly distributed, sample sizes required to detect at least one resistant individual (resistance detection) with a probability of 0.95 were 300 (1%) and 50 (10% and 20%); whereas, when resistant individuals were patchily distributed, using systematic sampling, sample sizes required for such detection were 6000 (1%), 600 (10%) and 300 (20%). Sample sizes of 900 and 400 would be required to detect ≥90% of resistant individuals (resistance documentation) with a probability of 0.95 when resistant individuals were randomly dispersed and present at a frequency of 10% and 20%, respectively; whereas, when resistant individuals were patchily distributed, using systematic sampling, a sample size of 3000 and 1500, respectively, was necessary. Small sample sizes either underestimated or overestimated the resistance frequency. A simple random sampling plan is, therefore, recommended for insecticide resistance detection and subsequent documentation.

The functional spectrum of low-frequency coding variation.

PubMed

Marth, Gabor T; Yu, Fuli; Indap, Amit R; Garimella, Kiran; Gravel, Simon; Leong, Wen Fung; Tyler-Smith, Chris; Bainbridge, Matthew; Blackwell, Tom; Zheng-Bradley, Xiangqun; Chen, Yuan; Challis, Danny; Clarke, Laura; Ball, Edward V; Cibulskis, Kristian; Cooper, David N; Fulton, Bob; Hartl, Chris; Koboldt, Dan; Muzny, Donna; Smith, Richard; Sougnez, Carrie; Stewart, Chip; Ward, Alistair; Yu, Jin; Xue, Yali; Altshuler, David; Bustamante, Carlos D; Clark, Andrew G; Daly, Mark; DePristo, Mark; Flicek, Paul; Gabriel, Stacey; Mardis, Elaine; Palotie, Aarno; Gibbs, Richard

2011-09-14

Rare coding variants constitute an important class of human genetic variation, but are underrepresented in current databases that are based on small population samples. Recent studies show that variants altering amino acid sequence and protein function are enriched at low variant allele frequency, 2 to 5%, but because of insufficient sample size it is not clear if the same trend holds for rare variants below 1% allele frequency. The 1000 Genomes Exon Pilot Project has collected deep-coverage exon-capture data in roughly 1,000 human genes, for nearly 700 samples. Although medical whole-exome projects are currently afoot, this is still the deepest reported sampling of a large number of human genes with next-generation technologies. According to the goals of the 1000 Genomes Project, we created effective informatics pipelines to process and analyze the data, and discovered 12,758 exonic SNPs, 70% of them novel, and 74% below 1% allele frequency in the seven population samples we examined. Our analysis confirms that coding variants below 1% allele frequency show increased population-specificity and are enriched for functional variants. This study represents a large step toward detecting and interpreting low frequency coding variation, clearly lays out technical steps for effective analysis of DNA capture data, and articulates functional and population properties of this important class of genetic variation.

High and low frequency unfolded partial least squares regression based on empirical mode decomposition for quantitative analysis of fuel oil samples.

PubMed

Bian, Xihui; Li, Shujuan; Lin, Ligang; Tan, Xiaoyao; Fan, Qingjie; Li, Ming

2016-06-21

Accurate prediction of the model is fundamental to the successful analysis of complex samples. To utilize abundant information embedded over frequency and time domains, a novel regression model is presented for quantitative analysis of hydrocarbon contents in the fuel oil samples. The proposed method named as high and low frequency unfolded PLSR (HLUPLSR), which integrates empirical mode decomposition (EMD) and unfolded strategy with partial least squares regression (PLSR). In the proposed method, the original signals are firstly decomposed into a finite number of intrinsic mode functions (IMFs) and a residue by EMD. Secondly, the former high frequency IMFs are summed as a high frequency matrix and the latter IMFs and residue are summed as a low frequency matrix. Finally, the two matrices are unfolded to an extended matrix in variable dimension, and then the PLSR model is built between the extended matrix and the target values. Coupled with Ultraviolet (UV) spectroscopy, HLUPLSR has been applied to determine hydrocarbon contents of light gas oil and diesel fuels samples. Comparing with single PLSR and other signal processing techniques, the proposed method shows superiority in prediction ability and better model interpretation. Therefore, HLUPLSR method provides a promising tool for quantitative analysis of complex samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Noise Spectroscopy Used in Biology

NASA Astrophysics Data System (ADS)

Žacik, Michal

This thesis contains glossary topic of spectroscopic measurement methods in broad bands of frequency. There is designed experimental measurement method for simple samples and biological samples measurements for noise spectroscopy in frequency range of 0.1 - 6 GHz, using broadband noise generator. There is realized the workplace and the measurement method is verified by measuring on selected samples. Measurements a displayed and analyzed.

Frequency of thermophilic Campylobacter in broiler chickens during industrial processing in a Southern Brazil slaughterhouse.

PubMed

Franchin, P R; Ogliari, P J; Batista, C R V

2007-04-01

1. The frequency of thermophilic Campylobacter spp. on broiler carcases was determined during processing in a Southern Brazil slaughterhouse. Samples were collected after defeathering, evisceration, water chilling and freezing. In addition, samples were obtained from the water of the chiller tank and from the surface of equipment in direct contact with the chicken. 2. Samples (335) were analysed and 71.3% were positive for Campylobacter. The frequency of Campylobacter spp. on carcases rinsed in BPW and skin samples from carcases was 49 of 72 (68.0%) after defeathering, 50 of 72 (69.4%) after evisceration, 61 of 72 (84.7%) after chilling, and 46 of 72 (63.9%) after freezing. Campylobacter was positive for 21 of 23 (91.3%) samples in the chilling water and for 12 of 24 (50.0%) samples on the table surface. 3. The frequency of qualitative analysis for Campylobacter spp. was reduced in frozen chickens, but not during the slaughtering process. The use of drinking water alone as a decontaminant to reduce the incidence of Campylobacter spp. during slaughter is therefore not sufficient. Furthermore, to ensure food safety, chickens must be cooked properly before consuming.

Method and apparatus for measuring butterfat and protein content using microwave absorption techniques

DOEpatents

Fryer, Michael O.; Hills, Andrea J.; Morrison, John L.

2000-01-01

A self calibrating method and apparatus for measuring butterfat and protein content based on measuring the microwave absorption of a sample of milk at several microwave frequencies. A microwave energy source injects microwave energy into the resonant cavity for absorption and reflection by the sample undergoing evaluation. A sample tube is centrally located in the resonant cavity passing therethrough and exposing the sample to the microwave energy. A portion of the energy is absorbed by the sample while another portion of the microwave energy is reflected back to an evaluation device such as a network analyzer. The frequency at which the reflected radiation is at a minimum within the cavity is combined with the scatter coefficient S.sub.11 as well as a phase change to calculate the butterfat content in the sample. The protein located within the sample may also be calculated in a likewise manner using the frequency, S.sub.11 and phase variables. A differential technique using a second resonant cavity containing a reference standard as a sample will normalize the measurements from the unknown sample and thus be self-calibrating. A shuttered mechanism will switch the microwave excitation between the unknown and the reference cavities. An integrated apparatus for measuring the butterfat content in milk using microwave absorption techniques is also presented.

Magnetic force microscopy with frequency-modulated capacitive tip-sample distance control

NASA Astrophysics Data System (ADS)

Zhao, X.; Schwenk, J.; Mandru, A. O.; Penedo, M.; Baćani, M.; Marioni, M. A.; Hug, H. J.

2018-01-01

In a step towards routinely achieving 10 nm spatial resolution with magnetic force microscopy, we have developed a robust method for active tip-sample distance control based on frequency modulation of the cantilever oscillation. It allows us to keep a well-defined tip-sample distance of the order of 10 nm within better than +/- 0.4 nm precision throughout the measurement even in the presence of energy dissipative processes, and is adequate for single-passage non-contact operation in vacuum. The cantilever is excited mechanically in a phase-locked loop to oscillate at constant amplitude on its first flexural resonance mode. This frequency is modulated by an electrostatic force gradient generated by tip-sample bias oscillating from a few hundred Hz up to a few kHz. The sum of the side bands’ amplitudes is a proxy for the tip-sample distance and can be used for tip-sample distance control. This method can also be extended to other scanning probe microscopy techniques.

Multi-Frequency Signal Detection Based on Frequency Exchange and Re-Scaling Stochastic Resonance and Its Application to Weak Fault Diagnosis.

PubMed

Liu, Jinjun; Leng, Yonggang; Lai, Zhihui; Fan, Shengbo

2018-04-25

Mechanical fault diagnosis usually requires not only identification of the fault characteristic frequency, but also detection of its second and/or higher harmonics. However, it is difficult to detect a multi-frequency fault signal through the existing Stochastic Resonance (SR) methods, because the characteristic frequency of the fault signal as well as its second and higher harmonics frequencies tend to be large parameters. To solve the problem, this paper proposes a multi-frequency signal detection method based on Frequency Exchange and Re-scaling Stochastic Resonance (FERSR). In the method, frequency exchange is implemented using filtering technique and Single SideBand (SSB) modulation. This new method can overcome the limitation of "sampling ratio" which is the ratio of the sampling frequency to the frequency of target signal. It also ensures that the multi-frequency target signals can be processed to meet the small-parameter conditions. Simulation results demonstrate that the method shows good performance for detecting a multi-frequency signal with low sampling ratio. Two practical cases are employed to further validate the effectiveness and applicability of this method.

Application of chemometrics to assess the influence of ultrasound frequency, Lactobacillus sakei culture and drying on beef jerky manufacture: Impact on amino acid profile, organic acids, texture and colour.

PubMed

Shikha Ojha, K; Granato, Daniel; Rajuria, Gaurav; Barba, Francisco J; Kerry, Joseph P; Tiwari, Brijesh K

2018-01-15

The effects of ultrasound (US) frequency, addition of Lactobacillus sakei culture and drying time on key nutritional (protein, amino acids, and organic acids) and physicochemical properties (texture and colour) of cultured and uncultured beef jerky were evaluated. Cultured and uncultured jerky samples were subjected to US frequencies of 25kHz, 33kHz and 45kHz for 30min prior to marination and drying. Principal component analysis demonstrated a significant effect of beef jerky processing conditions on physicochemical properties. Taurine content of jerky samples was found to increase with an increase in ultrasonic frequencies for cultured samples. No significant changes in colour values were observed for ultrasound pre-treated and control samples. Interactive effects of culture treatment, drying and ultrasonic frequency were observed. This study demonstrates that the nutritional profile of beef jerky can be improved through the incorporation of L. sakei. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interactive rendering of acquired materials on dynamic geometry using frequency analysis.

PubMed

Bagher, Mahdi Mohammad; Soler, Cyril; Subr, Kartic; Belcour, Laurent; Holzschuch, Nicolas

2013-05-01

Shading acquired materials with high-frequency illumination is computationally expensive. Estimating the shading integral requires multiple samples of the incident illumination. The number of samples required may vary across the image, and the image itself may have high- and low-frequency variations, depending on a combination of several factors. Adaptively distributing computational budget across the pixels for shading is a challenging problem. In this paper, we depict complex materials such as acquired reflectances, interactively, without any precomputation based on geometry. In each frame, we first estimate the frequencies in the local light field arriving at each pixel, as well as the variance of the shading integrand. Our frequency analysis accounts for combinations of a variety of factors: the reflectance of the object projecting to the pixel, the nature of the illumination, the local geometry and the camera position relative to the geometry and lighting. We then exploit this frequency information (bandwidth and variance) to adaptively sample for reconstruction and integration. For example, fewer pixels per unit area are shaded for pixels projecting onto diffuse objects, and fewer samples are used for integrating illumination incident on specular objects.

Commercial video frame rates can produce reliable results for both normal and CP spastic gait's spatiotemporal, angular, and linear displacement variables.

PubMed

Nikodelis, Thomas; Moscha, Dimitra; Metaxiotis, Dimitris; Kollias, Iraklis

2011-08-01

To investigate what sampling frequency is adequate for gait, the correlation of spatiotemporal parameters and the kinematic differences, between normal and CP spastic gait, for three sampling frequencies (100 Hz, 50 Hz, 25 Hz) were assessed. Spatiotemporal, angular, and linear displacement variables in the sagittal plane along with their 1st and 2nd derivatives were analyzed. Spatiotemporal stride parameters were highly correlated among the three sampling frequencies. The statistical model (2 × 3 ANOVA) gave no interactions between the factors group and frequency, indicating that group differences were invariant of sampling frequency. Lower frequencies led to smoother curves for all the variables, with a loss of information though, especially for the 2nd derivatives, having a homologous effect as the one of oversmoothing. It is proposed that in the circumstance that only spatiotemporal stride parameters, as well as angular and linear displacements are to be used, in gait reports, then commercial video camera speeds (25/30 Hz, 50/60 Hz when deinterlaced) can be considered as a low-cost solution to produce acceptable results.

Dielectric studies on PEG-LTMS based polymer composites

NASA Astrophysics Data System (ADS)

Patil, Ravikumar V.; Praveen, D.; Damle, R.

2018-02-01

PEG LTMS based polymer composites were prepared and studied for dielectric constant variation with frequency and temperature as a potential candidate with better dielectric properties. Solution cast technique is used for the preparation of polymer composite with five different compositions. Samples show variation in dielectric constant with frequency and temperature. Dielectric constant is large at low frequencies and higher temperatures. Samples with larger space charges have shown larger dielectric constant. The highest dielectric constant observed was about 29244 for PEG25LTMS sample at 100Hz and 312 K.

A Note on a Sampling Theorem for Functions over GF(q)n Domain

NASA Astrophysics Data System (ADS)

Ukita, Yoshifumi; Saito, Tomohiko; Matsushima, Toshiyasu; Hirasawa, Shigeichi

In digital signal processing, the sampling theorem states that any real valued function ƒ can be reconstructed from a sequence of values of ƒ that are discretely sampled with a frequency at least twice as high as the maximum frequency of the spectrum of ƒ. This theorem can also be applied to functions over finite domain. Then, the range of frequencies of ƒ can be expressed in more detail by using a bounded set instead of the maximum frequency. A function whose range of frequencies is confined to a bounded set is referred to as bandlimited function. And a sampling theorem for bandlimited functions over Boolean domain has been obtained. Here, it is important to obtain a sampling theorem for bandlimited functions not only over Boolean domain (GF(q)n domain) but also over GF(q)n domain, where q is a prime power and GF(q) is Galois field of order q. For example, in experimental designs, although the model can be expressed as a linear combination of the Fourier basis functions and the levels of each factor can be represented by GF(q)n, the number of levels often take a value greater than two. However, the sampling theorem for bandlimited functions over GF(q)n domain has not been obtained. On the other hand, the sampling points are closely related to the codewords of a linear code. However, the relation between the parity check matrix of a linear code and any distinct error vectors has not been obtained, although it is necessary for understanding the meaning of the sampling theorem for bandlimited functions. In this paper, we generalize the sampling theorem for bandlimited functions over Boolean domain to a sampling theorem for bandlimited functions over GF(q)n domain. We also present a theorem for the relation between the parity check matrix of a linear code and any distinct error vectors. Lastly, we clarify the relation between the sampling theorem for functions over GF(q)n domain and linear codes.

Influence of sampling frequency and load calculation methods on quantification of annual river nutrient and suspended solids loads.

PubMed

Elwan, Ahmed; Singh, Ranvir; Patterson, Maree; Roygard, Jon; Horne, Dave; Clothier, Brent; Jones, Geoffrey

2018-01-11

Better management of water quality in streams, rivers and lakes requires precise and accurate estimates of different contaminant loads. We assessed four sampling frequencies (2 days, weekly, fortnightly and monthly) and five load calculation methods (global mean (GM), rating curve (RC), ratio estimator (RE), flow-stratified (FS) and flow-weighted (FW)) to quantify loads of nitrate-nitrogen (NO 3 - -N), soluble inorganic nitrogen (SIN), total nitrogen (TN), dissolved reactive phosphorus (DRP), total phosphorus (TP) and total suspended solids (TSS), in the Manawatu River, New Zealand. The estimated annual river loads were compared to the reference 'true' loads, calculated using daily measurements of flow and water quality from May 2010 to April 2011, to quantify bias (i.e. accuracy) and root mean square error 'RMSE' (i.e. accuracy and precision). The GM method resulted into relatively higher RMSE values and a consistent negative bias (i.e. underestimation) in estimates of annual river loads across all sampling frequencies. The RC method resulted in the lowest RMSE for TN, TP and TSS at monthly sampling frequency. Yet, RC highly overestimated the loads for parameters that showed dilution effect such as NO 3 - -N and SIN. The FW and RE methods gave similar results, and there was no essential improvement in using RE over FW. In general, FW and RE performed better than FS in terms of bias, but FS performed slightly better than FW and RE in terms of RMSE for most of the water quality parameters (DRP, TP, TN and TSS) using a monthly sampling frequency. We found no significant decrease in RMSE values for estimates of NO 3 - N, SIN, TN and DRP loads when the sampling frequency was increased from monthly to fortnightly. The bias and RMSE values in estimates of TP and TSS loads (estimated by FW, RE and FS), however, showed a significant decrease in the case of weekly or 2-day sampling. This suggests potential for a higher sampling frequency during flow peaks for more precise and accurate estimates of annual river loads for TP and TSS, in the study river and other similar conditions.

Projects procedure guide : sampling frequencies for materials testing and inspection

DOT National Transportation Integrated Search

2002-02-01

The Bureau of Materials and Physical Research's Project Procedures Guide (PPG) is used as a resource for determining reasonable inspection procedures and sampling frequencies for materials used in highway construction. This Manual seeks to establish ...

The effect of sampling rate on interpretation of the temporal characteristics of radiative and convective heating in wildland flames

Treesearch

David Frankman; Brent W. Webb; Bret W. Butler; Daniel Jimenez; Michael Harrington

2012-01-01

Time-resolved radiative and convective heating measurements were collected on a prescribed burn in coniferous fuels at a sampling frequency of 500 Hz. Evaluation of the data in the time and frequency domain indicate that this sampling rate was sufficient to capture the temporal fluctuations of radiative and convective heating. The convective heating signal contained...

Effect of substrate bending on the piezoelectric measurement of PZT thin film

NASA Astrophysics Data System (ADS)

Xu, Xiaohui; Tang, Jianhong; He, Liangna

2009-05-01

Bonding conditions between PZT thin film and sample holder greatly affect the strain measurement of the PZT sample. The influence of various bonding conditions on the measured displacement were analyzed using finite element analysis (FEA). One-end fixed sample induces the maximum bending displacement. Experiments were performed on sol-gel derived PZT thin film. The voltage-displacement curve and "butterfly" loop were measured using laser Doppler method with phase detection. Experimental results agreed well with the simulated ones. The measured frequency dependence of piezoelectric response of PZT thin film indicated that, if the operating frequency was lower than 2 kHz, good bonding effect could be obtained when the entire back surface of the sample was glued to a rigid supporter using epoxy resin. A simple bonding model which considered the adhesives as a spring was used to estimate the frequency response of PZT thin film sample.

Modulation infrared thermometry of caloric effects at up to kHz frequencies

NASA Astrophysics Data System (ADS)

Döntgen, Jago; Rudolph, Jörg; Waske, Anja; Hägele, Daniel

2018-03-01

We present a novel non-contact method for the direct measurement of caloric effects in low volume samples. The adiabatic temperature change ΔT of a magnetocaloric sample is very sensitively determined from thermal radiation. Rapid modulation of ΔT is induced by an oscillating external magnetic field. Detection of thermal radiation with a mercury-cadmium-telluride detector allows for measurements at field frequencies exceeding 1 kHz. In contrast to thermoacoustic methods, our method can be employed in vacuum which enhances adiabatic conditions especially in the case of small volume samples. Systematic measurements of the magnetocaloric effect as a function of temperature, magnetic field amplitude, and modulation frequency give a detailed picture of the thermal behavior of the sample. Highly sensitive measurements of the magnetocaloric effect are demonstrated on a 2 mm thick sample of gadolinium and a 60 μm thick Fe80B12Nb8 ribbon.

Extragalactic Peaked-spectrum Radio Sources at Low Frequencies

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

Callingham, J. R.; Gaensler, B. M.; Sadler, E. M.

We present a sample of 1483 sources that display spectral peaks between 72 MHz and 1.4 GHz, selected from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. The GLEAM survey is the widest fractional bandwidth all-sky survey to date, ideal for identifying peaked-spectrum sources at low radio frequencies. Our peaked-spectrum sources are the low-frequency analogs of gigahertz-peaked spectrum (GPS) and compact-steep spectrum (CSS) sources, which have been hypothesized to be the precursors to massive radio galaxies. Our sample more than doubles the number of known peaked-spectrum candidates, and 95% of our sample have a newly characterized spectral peak.more » We highlight that some GPS sources peaking above 5 GHz have had multiple epochs of nuclear activity, and we demonstrate the possibility of identifying high-redshift ( z > 2) galaxies via steep optically thin spectral indices and low observed peak frequencies. The distribution of the optically thick spectral indices of our sample is consistent with past GPS/CSS samples but with a large dispersion, suggesting that the spectral peak is a product of an inhomogeneous environment that is individualistic. We find no dependence of observed peak frequency with redshift, consistent with the peaked-spectrum sample comprising both local CSS sources and high-redshift GPS sources. The 5 GHz luminosity distribution lacks the brightest GPS and CSS sources of previous samples, implying that a convolution of source evolution and redshift influences the type of peaked-spectrum sources identified below 1 GHz. Finally, we discuss sources with optically thick spectral indices that exceed the synchrotron self-absorption limit.« less

Resonant ultrasound spectroscopy for materials with high damping and samples of arbitrary geometry

DOE PAGES

Remillieux, Marcel C.; Ulrich, T. J.; Payan, Cédric; ...

2015-07-23

This paper describes resonant ultrasound spectroscopy (RUS) as a powerful and established technique for measuring elastic constants of a material with general anisotropy. The first step of this technique consists of extracting resonance frequencies and damping from the vibrational frequency spectrum measured on a sample with free boundary conditions. An inversion technique is then used to retrieve the elastic tensor from the measured resonance frequencies. As originally developed, RUS has been mostly applicable to (i) materials with small damping such that the resonances of the sample are well separated and (ii) samples with simple geometries for which analytical solutions exist.more » In this paper, these limitations are addressed with a new RUS approach adapted to materials with high damping and samples of arbitrary geometry. Resonances are extracted by fitting a sum of exponentially damped sinusoids to the measured frequency spectrum. The inversion of the elastic tensor is achieved with a genetic algorithm, which allows searching for a global minimum within a discrete and relatively wide solution space. First, the accuracy of the proposed approach is evaluated against numerical data simulated for samples with isotropic symmetry and transversely isotropic symmetry. Subsequently, the applicability of the approach is demonstrated using experimental data collected on a composite structure consisting of a cylindrical sample of Berea sandstone glued to a large piezoelectric disk. In the proposed experiments, RUS is further enhanced by the use of a 3-D laser vibrometer allowing the visualization of most of the modes in the frequency band studied.« less

Study of the Effect of Temporal Sampling Frequency on DSCOVR Observations Using the GEOS-5 Nature Run Results. Part II; Cloud Coverage

NASA Technical Reports Server (NTRS)

Holdaway, Daniel; Yang, Yuekui

2016-01-01

This is the second part of a study on how temporal sampling frequency affects satellite retrievals in support of the Deep Space Climate Observatory (DSCOVR) mission. Continuing from Part 1, which looked at Earth's radiation budget, this paper presents the effect of sampling frequency on DSCOVR-derived cloud fraction. The output from NASA's Goddard Earth Observing System version 5 (GEOS-5) Nature Run is used as the "truth". The effect of temporal resolution on potential DSCOVR observations is assessed by subsampling the full Nature Run data. A set of metrics, including uncertainty and absolute error in the subsampled time series, correlation between the original and the subsamples, and Fourier analysis have been used for this study. Results show that, for a given sampling frequency, the uncertainties in the annual mean cloud fraction of the sunlit half of the Earth are larger over land than over ocean. Analysis of correlation coefficients between the subsamples and the original time series demonstrates that even though sampling at certain longer time intervals may not increase the uncertainty in the mean, the subsampled time series is further and further away from the "truth" as the sampling interval becomes larger and larger. Fourier analysis shows that the simulated DSCOVR cloud fraction has underlying periodical features at certain time intervals, such as 8, 12, and 24 h. If the data is subsampled at these frequencies, the uncertainties in the mean cloud fraction are higher. These results provide helpful insights for the DSCOVR temporal sampling strategy.

Nonlinear Stress/Strain Behavior of a Synthetic Porous Medium at Seismic Frequencies

NASA Astrophysics Data System (ADS)

Roberts, P. M.; Ibrahim, R. H.

2008-12-01

Laboratory experiments on porous core samples have shown that seismic-band (100 Hz or less) mechanical, axial stress/strain cycling of the porous matrix can influence the transport behavior of fluids and suspended particles during steady-state fluid flow through the cores. In conjunction with these stimulated transport experiments, measurements of the applied dynamic axial stress/strain were made to investigate the nonlinear mechanical response of porous media for a poorly explored range of frequencies from 1 to 40 Hz. A unique core-holder apparatus that applies low-frequency mechanical stress/strain to 2.54-cm-diameter porous samples during constant-rate fluid flow was used for these experiments. Applied stress was measured with a load cell in series with the source and porous sample, and the resulting strain was measured with an LVDT attached to the core face. A synthetic porous system consisting of packed 1-mm-diameter glass beads was used to investigate both stress/strain and stimulated mass-transport behavior under idealized conditions. The bead pack was placed in a rubber sleeve and static confining stresses of 2.4 MPa radial and 1.7 MPa axial were applied to the sample. Sinusoidal stress oscillations were applied to the sample at 1 to 40 Hz over a range of RMS stress amplitude from 37 to 275 kPa. Dynamic stress/strain was measured before and after the core was saturated with deionized water. The slope of the linear portion of each stress/strain hysteresis loop was used to estimate Young's modulus as a function of frequency and amplitude for both the dry and wet sample. The modulus was observed to increase after the dry sample was saturated. For both dry and wet cases, the modulus decreased with increasing dynamic RMS stress amplitude at a constant frequency of 23 Hz. At constant RMS stress amplitude, the modulus increased with increasing frequency for the wet sample but remained constant for the dry sample. The observed nonlinear behavior of Young's modulus and the dependence of stress/strain hysteresis on strain amplitude and frequency have implications on how seismic waves can influence the mechanical properties of granular porous materials in the Earth. This work was funded by the U.S. Department of Energy Basic Energy Sciences Program under the Los Alamos National Laboratory contract no. DE-AC52-06NA25396.

An algorithm for extraction of periodic signals from sparse, irregularly sampled data

NASA Technical Reports Server (NTRS)

Wilcox, J. Z.

1994-01-01

Temporal gaps in discrete sampling sequences produce spurious Fourier components at the intermodulation frequencies of an oscillatory signal and the temporal gaps, thus significantly complicating spectral analysis of such sparsely sampled data. A new fast Fourier transform (FFT)-based algorithm has been developed, suitable for spectral analysis of sparsely sampled data with a relatively small number of oscillatory components buried in background noise. The algorithm's principal idea has its origin in the so-called 'clean' algorithm used to sharpen images of scenes corrupted by atmospheric and sensor aperture effects. It identifies as the signal's 'true' frequency that oscillatory component which, when passed through the same sampling sequence as the original data, produces a Fourier image that is the best match to the original Fourier space. The algorithm has generally met with succession trials with simulated data with a low signal-to-noise ratio, including those of a type similar to hourly residuals for Earth orientation parameters extracted from VLBI data. For eight oscillatory components in the diurnal and semidiurnal bands, all components with an amplitude-noise ratio greater than 0.2 were successfully extracted for all sequences and duty cycles (greater than 0.1) tested; the amplitude-noise ratios of the extracted signals were as low as 0.05 for high duty cycles and long sampling sequences. When, in addition to these high frequencies, strong low-frequency components are present in the data, the low-frequency components are generally eliminated first, by employing a version of the algorithm that searches for non-integer multiples of the discrete FET minimum frequency.

Using geostatistics to evaluate cleanup goals

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

Marcon, M.F.; Hopkins, L.P.

1995-12-01

Geostatistical analysis is a powerful predictive tool typically used to define spatial variability in environmental data. The information from a geostatistical analysis using kriging, a geostatistical. tool, can be taken a step further to optimize sampling location and frequency and help quantify sampling uncertainty in both the remedial investigation and remedial design at a hazardous waste site. Geostatistics were used to quantify sampling uncertainty in attainment of a risk-based cleanup goal and determine the optimal sampling frequency necessary to delineate the horizontal extent of impacted soils at a Gulf Coast waste site.

Resolution-enhancement and sampling error correction based on molecular absorption line in frequency scanning interferometry

NASA Astrophysics Data System (ADS)

Pan, Hao; Qu, Xinghua; Shi, Chunzhao; Zhang, Fumin; Li, Yating

2018-06-01

The non-uniform interval resampling method has been widely used in frequency modulated continuous wave (FMCW) laser ranging. In the large-bandwidth and long-distance measurements, the range peak is deteriorated due to the fiber dispersion mismatch. In this study, we analyze the frequency-sampling error caused by the mismatch and measure it using the spectroscopy of molecular frequency references line. By using the adjacent points' replacement and spline interpolation technique, the sampling errors could be eliminated. The results demonstrated that proposed method is suitable for resolution-enhancement and high-precision measurement. Moreover, using the proposed method, we achieved the precision of absolute distance less than 45 μm within 8 m.

Power system frequency estimation based on an orthogonal decomposition method

NASA Astrophysics Data System (ADS)

Lee, Chih-Hung; Tsai, Men-Shen

2018-06-01

In recent years, several frequency estimation techniques have been proposed by which to estimate the frequency variations in power systems. In order to properly identify power quality issues under asynchronously-sampled signals that are contaminated with noise, flicker, and harmonic and inter-harmonic components, a good frequency estimator that is able to estimate the frequency as well as the rate of frequency changes precisely is needed. However, accurately estimating the fundamental frequency becomes a very difficult task without a priori information about the sampling frequency. In this paper, a better frequency evaluation scheme for power systems is proposed. This method employs a reconstruction technique in combination with orthogonal filters, which may maintain the required frequency characteristics of the orthogonal filters and improve the overall efficiency of power system monitoring through two-stage sliding discrete Fourier transforms. The results showed that this method can accurately estimate the power system frequency under different conditions, including asynchronously sampled signals contaminated by noise, flicker, and harmonic and inter-harmonic components. The proposed approach also provides high computational efficiency.

High-speed AFM and the reduction of tip-sample forces

NASA Astrophysics Data System (ADS)

Miles, Mervyn; Sharma, Ravi; Picco, Loren

High-speed DC-mode AFM has been shown to be routinely capable of imaging at video rate, and, if required, at over 1000 frames per second. At sufficiently high tip-sample velocities in ambient conditions, the tip lifts off the sample surface in a superlubricity process which reduces the level of shear forces imposed on the sample by the tip and therefore reduces the potential damage and distortion of the sample being imaged. High-frequency mechanical oscillations, both lateral and vertical, have been reported to reduced the tip-sample frictional forces. We have investigated the effect of combining linear high-speed scanning with these small amplitude high-frequency oscillations with the aim of reducing further the force interaction in high-speed imaging. Examples of this new version of high-speed AFM imaging will be presented for biological samples.

Frequency shift measurement in shock-compressed materials

DOEpatents

Moore, David S.; Schmidt, Stephen C.

1985-01-01

A method for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the shock front advancing through the sample, thereby minimizing adverse effects of refraction.

Digital quadrature phase detection

DOEpatents

Smith, James A.; Johnson, John A.

1992-01-01

A system for detecting the phase of a frequency of phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2.pi. when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2.pi. when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention.

Frequency shift measurement in shock-compressed materials

DOEpatents

Moore, D.S.; Schmidt, S.C.

1984-02-21

A method is disclosed for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the stock front advancing through the sample, thereby minimizing adverse effects of refraction.

Admittance of multiterminal quantum Hall conductors at kilohertz frequencies

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

Hernández, C.; Consejo, C.; Chaubet, C., E-mail: christophe.chaubet@univ-montp2.fr

2014-03-28

We present an experimental study of the low frequency admittance of quantum Hall conductors in the [100 Hz, 1 MHz] frequency range. We show that the frequency dependence of the admittance of the sample strongly depends on the topology of the contacts connections. Our experimental results are well explained within the Christen and Büttiker approach for finite frequency transport in quantum Hall edge channels taking into account the influence of the coaxial cables capacitance. In the Hall bar geometry, we demonstrate that there exists a configuration in which the cable capacitance does not influence the admittance measurement of the sample. In thismore » case, we measure the electrochemical capacitance of the sample and observe its dependence on the filling factor.« less

Digital quadrature phase detection

DOEpatents

Smith, J.A.; Johnson, J.A.

1992-05-26

A system for detecting the phase of a frequency or phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2[pi] when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2[pi] when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention. 6 figs.

40 CFR 61.32 - Emission standard.

Code of Federal Regulations, 2010 CFR

2010-07-01

... frequency of calibration. (b) Method of sample analysis. (c) Averaging technique for determining 30-day...) Plant and sampling area plots showing emission points and sampling sites. Topographic features...

Method and Apparatus for Measuring Near-Angle Scattering of Mirror Coatings

NASA Technical Reports Server (NTRS)

Chipman, Russell A. (Inventor); Daugherty, Brian J. (Inventor); McClain, Stephen C. (Inventor); Macenka, Steven A. (Inventor)

2013-01-01

Disclosed herein is a method of determining the near angle scattering of a sample reflective surface comprising the steps of: a) splitting a beam of light having a coherence length of greater than or equal to about 2 meters into a sample beam and a reference beam; b) frequency shifting both the sample beam and the reference beam to produce a fixed beat frequency between the sample beam and the reference beam; c) directing the sample beam through a focusing lens and onto the sample reflective surface, d) reflecting the sample beam from the sample reflective surface through a detection restriction disposed on a movable stage; e) recombining the sample beam with the reference beam to form a recombined beam, followed by f) directing the recombined beam to a detector and performing heterodyne analysis on the recombined beam to measure the near-angle scattering of the sample reflective surface, wherein the position of the detection restriction relative to the sample beam is varied to occlude at least a portion of the sample beam to measure the near-angle scattering of the sample reflective surface. An apparatus according to the above method is also disclosed.

Piezoelectric-tuned microwave cavity for absorption spectrometry

DOEpatents

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

1978-01-01

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

Sampling strategies for estimating acute and chronic exposures of pesticides in streams

USGS Publications Warehouse

Crawford, Charles G.

2004-01-01

The Food Quality Protection Act of 1996 requires that human exposure to pesticides through drinking water be considered when establishing pesticide tolerances in food. Several systematic and seasonally weighted systematic sampling strategies for estimating pesticide concentrations in surface water were evaluated through Monte Carlo simulation, using intensive datasets from four sites in northwestern Ohio. The number of samples for the strategies ranged from 4 to 120 per year. Sampling strategies with a minimal sampling frequency outside the growing season can be used for estimating time weighted mean and percentile concentrations of pesticides with little loss of accuracy and precision, compared to strategies with the same sampling frequency year round. Less frequent sampling strategies can be used at large sites. A sampling frequency of 10 times monthly during the pesticide runoff period at a 90 km 2 basin and four times monthly at a 16,400 km2 basin provided estimates of the time weighted mean, 90th, 95th, and 99th percentile concentrations that fell within 50 percent of the true value virtually all of the time. By taking into account basin size and the periodic nature of pesticide runoff, costs of obtaining estimates of time weighted mean and percentile pesticide concentrations can be minimized.

Haptoglobin polymorphism among Saharian and West African groups. Haptoglobin phenotype determination by radioimmunoelectrophoresis on Hp O samples.

PubMed Central

Constans, J; Viau, M; Gouaillard, C; Clerc, A

1981-01-01

The haptoglobin (Hp) polymorphism is investigated in 11 African groups living in an area from the Algerian Sahara to Central Africa. More than 4,000 samples were examined. In the Saharian samples, the Hp1 gene frequency is higher than in any other African group. From north to south, a decrease in the Hp1 gene frequency is observed; in the Pygmy sample only, this frequency is lower than the frequency of the Hp2 gene. By means of a sensitive radioimmunoelectrophoresis, the presence of a residual Hp in Hp O sera in which the Hp polymorphism can also be determined can be revealed. Absence of Hp 1-1 and significant excess of Hp 2-2 individuals were observed. More Hp 2-1M phenotypes were detected in the Hp O population than in the non-Hp O population examined. In the Hp O samples, the influence of the phenotype distribution on the Hp gene frequencies is discussed. The heavy polymers of the Hp related to the presence of the alpha 2 chain (Hp2 gene product) are involved only in the biological mechanisms responsible for the presence of Hp O and Hp 2-1 M phenotypes among African groups. Images Fig. 1 PMID:7258189

A Simple Joint Estimation Method of Residual Frequency Offset and Sampling Frequency Offset for DVB Systems

NASA Astrophysics Data System (ADS)

Kwon, Ki-Won; Cho, Yongsoo

This letter presents a simple joint estimation method for residual frequency offset (RFO) and sampling frequency offset (STO) in OFDM-based digital video broadcasting (DVB) systems. The proposed method selects a continual pilot (CP) subset from an unsymmetrically and non-uniformly distributed CP set to obtain an unbiased estimator. Simulation results show that the proposed method using a properly selected CP subset is unbiased and performs robustly.

Dual THz comb spectroscopy

NASA Astrophysics Data System (ADS)

Yasui, Takeshi

2017-08-01

Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10-7 in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy.

Multi-Frequency Signal Detection Based on Frequency Exchange and Re-Scaling Stochastic Resonance and Its Application to Weak Fault Diagnosis

PubMed Central

Leng, Yonggang; Fan, Shengbo

2018-01-01

Mechanical fault diagnosis usually requires not only identification of the fault characteristic frequency, but also detection of its second and/or higher harmonics. However, it is difficult to detect a multi-frequency fault signal through the existing Stochastic Resonance (SR) methods, because the characteristic frequency of the fault signal as well as its second and higher harmonics frequencies tend to be large parameters. To solve the problem, this paper proposes a multi-frequency signal detection method based on Frequency Exchange and Re-scaling Stochastic Resonance (FERSR). In the method, frequency exchange is implemented using filtering technique and Single SideBand (SSB) modulation. This new method can overcome the limitation of "sampling ratio" which is the ratio of the sampling frequency to the frequency of target signal. It also ensures that the multi-frequency target signals can be processed to meet the small-parameter conditions. Simulation results demonstrate that the method shows good performance for detecting a multi-frequency signal with low sampling ratio. Two practical cases are employed to further validate the effectiveness and applicability of this method. PMID:29693577

Sub-nano tesla magnetic imaging based on room-temperature magnetic flux sensors with vibrating sample magnetometry

NASA Astrophysics Data System (ADS)

Adachi, Yoshiaki; Oyama, Daisuke

2017-05-01

We developed a two-dimensional imaging method for weak magnetic charge distribution using a commercially available magnetic impedance sensor whose magnetic field resolution is 10 pT/Hz1/2 at 10 Hz. When we applied the vibrating sample magnetometry, giving a minute mechanical vibration to the sample and detecting magnetic signals modulated by the vibration frequency, the effects of 1/f noise and the environmental low-frequency band noise were suppressed, and a weak magnetic charge distribution was obtained without magnetic shielding. Furthermore, improvement in the spatial resolution was also expected when the signals were demodulated at the second harmonic frequency of the vibration. In this paper, a preliminary magnetic charge imaging using the vibrating sample magnetometry and its results are demonstrated.

Improved Dielectric Properties via Mechano-Chemical Activation in Ba0.80Pb0.20TiO3 Ceramics

NASA Astrophysics Data System (ADS)

Kumar, Parveen; Rani, Renu; Singh, Sangeeta; Juneja, J. K.; Prakash, Chandra; Raina, K. K.

2011-12-01

The present report is about the preparation and dielectric properties of commonly used Ba0.80Pb0.20TiO3 (BPT) ferroelectric ceramic via Mechano-Chemical Activation (MCA). Results were compared by the BPT sample prepared by conventional solid state method. The BPT sample prepared via MCA technique was found to have decreased tetragonality, dielectric constant value (ɛRT = 450 and ɛmax = 6170) approximately double the value for sample prepared by conventional method (ɛRT = 260 and ɛmax = 3275). Also, the sample prepared by MCA was found to be less frequency dependent. Thus, the BPT sample prepared via MCA is more suitable for capacitor applications requiring lesser frequency dependency than the conventionally prepared BPT sample.

Measurement of sample temperatures under magic-angle spinning from the chemical shift and spin-lattice relaxation rate of 79Br in KBr powder

PubMed Central

Thurber, Kent R.; Tycko, Robert

2009-01-01

Accurate determination of sample temperatures in solid state nuclear magnetic resonance (NMR) with magic-angle spinning (MAS) can be problematic, particularly because frictional heating and heating by radio-frequency irradiation can make the internal sample temperature significantly different from the temperature outside the MAS rotor. This paper demonstrates the use of 79Br chemical shifts and spin-lattice relaxation rates in KBr powder as temperature-dependent parameters for the determination of internal sample temperatures. Advantages of this method include high signal-to-noise, proximity of the 79Br NMR frequency to that of 13C, applicability from 20 K to 320 K or higher, and simultaneity with adjustment of the MAS axis direction. We show that spin-lattice relaxation in KBr is driven by a quadrupolar mechanism. We demonstrate a simple approach to including KBr powder in hydrated samples, such as biological membrane samples, hydrated amyloid fibrils, and hydrated microcrystalline proteins, that allows direct assessment of the effects of frictional and radio-frequency heating under experimentally relevant conditions. PMID:18930418

Measurement of sample temperatures under magic-angle spinning from the chemical shift and spin-lattice relaxation rate of 79Br in KBr powder.

PubMed

Thurber, Kent R; Tycko, Robert

2009-01-01

Accurate determination of sample temperatures in solid state nuclear magnetic resonance (NMR) with magic-angle spinning (MAS) can be problematic, particularly because frictional heating and heating by radio-frequency irradiation can make the internal sample temperature significantly different from the temperature outside the MAS rotor. This paper demonstrates the use of (79)Br chemical shifts and spin-lattice relaxation rates in KBr powder as temperature-dependent parameters for the determination of internal sample temperatures. Advantages of this method include high signal-to-noise, proximity of the (79)Br NMR frequency to that of (13)C, applicability from 20 K to 320 K or higher, and simultaneity with adjustment of the MAS axis direction. We show that spin-lattice relaxation in KBr is driven by a quadrupolar mechanism. We demonstrate a simple approach to including KBr powder in hydrated samples, such as biological membrane samples, hydrated amyloid fibrils, and hydrated microcrystalline proteins, that allows direct assessment of the effects of frictional and radio-frequency heating under experimentally relevant conditions.

New HLA haplotype frequency reference standards: high-resolution and large sample typing of HLA DR-DQ haplotypes in a sample of European Americans.

PubMed

Klitz, W; Maiers, M; Spellman, S; Baxter-Lowe, L A; Schmeckpeper, B; Williams, T M; Fernandez-Viña, M

2003-10-01

A collaborative study involving a large sample of European Americans was typed for the histocompatibility loci of the HLA DR-DQ region and subjected to intensive typing validation measures in order to accurately determine haplotype composition and frequency. The resulting tables have immediate application to HLA typing and allogeneic transplantation. The loci within the DR-DQ region are especially valuable for such an undertaking because of their tight linkage and high linkage disequilibrium. The 3798 haplotypes, derived from 1899 unrelated individuals, had a total of 75 distinct DRB1-DQA1-DQB1 haplotypes. The frequency distribution of the haplotypes was right skewed with haplotypes occurring at a frequency of less than 1% numbering 59 and yet constituting less than 12% of the total sample. Given DRB1 typing, it was possible to infer the exact DQA1 and DQB1 composition of a haplotype with high confidence (>90% likelihood) in 21 of the 35 high-resolution DRB1 alleles present in the sample. Of the DRB1 alleles without high reliability for DQ haplotype inference, only *0401, *0701 and *1302 were common, the remaining 11 DRB1 alleles constituting less than 5% of the total sample. This approach failed for the 13 serologically equivalent DR alleles in which only 33% of DQ haplotypes could be reliably inferred. The 36 DQA1-DQB1 haplotypes present in the total sample conformed to the known pattern of permissible heterodimers. Four DQA1-DQB1 haplotypes, all rare, are reported here for the first time. The haplotype frequency tables are suitable as a reference standard for HLA typing of the DR and DQ loci in European Americans.

Patterns and predictors of health service utilization in adolescents with pain: comparison between a community and a clinical pain sample.

PubMed

Toliver-Sokol, Marisol; Murray, Caitlin B; Wilson, Anna C; Lewandowski, Amy; Palermo, Tonya M

2011-07-01

There is limited research describing the patterns of healthcare utilization in adolescents with chronic pain. This study describes healthcare utilization in a clinical chronic pain sample, and compares the patterns of service use of this group to a community sample with intermittent pain complaints. We also investigated demographic and clinical factors that predicted healthcare visits and medication use in the clinical sample. Data on 117 adolescents (aged 12-18; n = 59 clinical pain sample, n = 58 community) were collected. Caregivers and adolescents reported on sociodemographics, medical visits, current medications, pain, activity limitations, and depression. As hypothesized, the clinical pain sample had higher rates of healthcare consultation on all types of medical visits (general, specialty care, complementary medicine, mental health, OT/PT), and higher medication use compared to the community sample. Regression analyses revealed that higher annual income, greater pain frequency, and higher levels of caregiver-reported activity limitations were associated with a greater number of healthcare visits for the total sample. Within the clinical pain sample, higher pain frequency and greater activity limitations (caregiver report) predicted more specialty care visits. Additionally, higher income and greater levels of depressive symptoms predicted a higher number of prescribed medications. This study contributes to the limited available data on health service and medication use in a clinical chronic pain sample versus a community sample of adolescents. We also identify clinical factors (pain frequency, parent-reported activity limitations, depressive symptoms) and demographic factors (gender, income) associated with healthcare utilization. Copyright © 2011 American Pain Society. Published by Elsevier Inc. All rights reserved.

Experimental and numerical modeling research of rubber material during microwave heating process

NASA Astrophysics Data System (ADS)

Chen, Hailong; Li, Tao; Li, Kunling; Li, Qingling

2018-05-01

This paper aims to investigate the heating behaviors of block rubber by experimental and simulated method. The COMSOL Multiphysics 5.0 software was utilized in numerical simulation work. The effects of microwave frequency, power and sample size on temperature distribution are examined. The effect of frequency on temperature distribution is obvious. The maximum and minimum temperatures of block rubber increase first and then decrease with frequency increasing. The microwave heating efficiency is maximum in the microwave frequency of 2450 MHz. However, more uniform temperature distribution is presented in other microwave frequencies. The influence of microwave power on temperature distribution is also remarkable. The smaller the power, the more uniform the temperature distribution on the block rubber. The effect of power on microwave heating efficiency is not obvious. The effect of sample size on temperature distribution is evidently found. The smaller the sample size, the more uniform the temperature distribution on the block rubber. However, the smaller the sample size, the lower the microwave heating efficiency. The results can serve as references for the research on heating rubber material by microwave technology.

Investigation of Barium Ferrite, Searching for Soft Magnetic Materials in High Frequency Applications

NASA Astrophysics Data System (ADS)

Wu, Shuang; Kanada, Isao; Mewes, Tim; Mewes, Claudia; Mankey, Gary; Ariake, Yusuke; Suzuki, Takao

Soft ferrites have been extensively and intensively applied for high frequency device applications. Among them, Ba-ferrites substituted by Mn and Ti are particularly attractive as future soft magnetic material candidates for advanced high frequency device applications. However, very little has been known as to the intrinsic magnetic properties, such as damping parameter, which is crucial to develop high frequency devices. In the present study, much effort has been focused on fabrication of single crystal Ba-ferrites and measurements of damping parameter by FMR. Ba-ferrite samples consisted of many grains with various sizes have been prepared. The saturation magnetization and the magnetic anisotropy field of the sample are in reasonable agreement with the values in literature. The resonances positions in the FMR spectra over a wide frequency range also comply with theoretical predictions. However, the complex resonance shapes observed makes it difficult to extract dynamic magnetic property. Possible reasons are the demagnetization field originating from irregular sample shape or existence of multiple grains in the samples. S.W. acknowledges the support under the TDK Scholar Program.

300 Area treated effluent disposal facility sampling schedule

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

Loll, C.M.

1994-10-11

This document is the interface between the 300 Area Liquid Effluent Process Engineering (LEPE) group and the Waste Sampling and Characterization Facility (WSCF), concerning process control samples. It contains a schedule for process control samples at the 300 Area TEDF which describes the parameters to be measured, the frequency of sampling and analysis, the sampling point, and the purpose for each parameter.

Poroelastic finite difference modeling of seismic attenuation and dispersion due to mesoscopic-scale heterogeneity

NASA Astrophysics Data System (ADS)

Masson, Y. J.; Pride, S. R.

2007-03-01

Seismic attenuation and dispersion are numerically determined for computer-generated porous materials that contain arbitrary amounts of mesoscopic-scale heterogeneity in the porous continuum properties. The local equations used to determine the poroelastic response within such materials are those of Biot (1962). Upon applying a step change in stress to samples containing mesoscopic-scale heterogeneity, the poroelastic response is determined using finite difference modeling, and the average strain throughout the sample computed, along with the effective complex and frequency-dependent elastic moduli of the sample. The ratio of the imaginary and real parts of these moduli determines the attenuation as a function of frequency associated with the modes of applied stress (pure compression and pure shear). By having a wide range of heterogeneity present, there exists a wide range of relaxation frequencies in the response with the result that the curves of attenuation as a function of frequency are broader than in existing analytical theories based on a single relaxation frequency. Analytical explanations are given for the various high-frequency and low-frequency asymptotic behavior observed in the numerical simulations. It is also shown that the overall level of attenuation of a given sample is proportional to the square of the incompressibility contrasts locally present.

Feasibility of zero tolerance for Salmonella on raw poultry

USDA-ARS?s Scientific Manuscript database

Ideally, poultry producing countries around the globe should use internationally standardized sampling methods for Salmonella. It is difficult to compare prevalence data from country-to-country when sample plan, sample type, sample frequency and laboratory media along with methods differ. The Europe...

Nonlinear Optical Effects in Liquid Crystals.

DTIC Science & Technology

1980-12-10

susceptibilities Lasers , Nematic, Cholesteric, Flexoelectric, Second-harmonic generation 20M AV*--YRAc rR-r, m, revere i It nf le4U7 siad Idsiully byr...samples are irradiated with laser beam at the fundamental frequency. The laser used in a Q-switched Nd-YAG laser . Sample alignment is achieved either...irradiated with laser beam at the fundamental frequency. The laser used is a Q-switched Nd-YAG laser . Sample alignment is achieved either with rubbing

Acoustic levitation and the Boltzmann-Ehrenfest principle

NASA Technical Reports Server (NTRS)

Putterman, S.; Rudnick, Joseph; Barmatz, M.

1989-01-01

The Boltzmann-Ehrenfest principle of adiabatic invariance relates the acoustic potential acting on a sample positioned in a single-mode cavity to the shift in resonant frequency caused by the presence of this sample. This general and simple relation applies to samples and cavities of arbitrary shape, dimension, and compressibility. Positioning forces and torques can, therefore, be determined from straightforward measurements of frequency shifts. Applications to the Rayleigh disk phenomenon and levitated cylinders are presented.

Towards the effect of acoustic emission (AE) sensor positioning within AE signal parameters in sliding on bulk ultrafine-grained materials

NASA Astrophysics Data System (ADS)

Filippov, A. V.; Tarasov, S. Yu.; Podgornykh, O. A.; Chazov, P. A.; Shamarin, N. N.; Filippova, E. O.

2017-12-01

The effect of AE sensor positioning on the bulk ultrafine-grained materials used for sliding against steel ball has been investigated. Two versions of AE sensor positioning have been tested and showed the different attenuation levels. The experimentally obtained AE signal waveforms have been analyzed under the AE signal parameters such as a median frequency and AE energy. It was established that the AE sensor positioned on the sample supporting plate in the vicinity of the sample tested allowed redistribution of the signal energy from a low-frequency to high-frequency range as well as extending the median frequency range as compared to those obtained by mounting the sensor on the immobile sample holder.

Metrology for terahertz time-domain spectrometers

NASA Astrophysics Data System (ADS)

Molloy, John F.; Naftaly, Mira

2015-12-01

In recent years the terahertz time-domain spectrometer (THz TDS) [1] has emerged as a key measurement device for spectroscopic investigations in the frequency range of 0.1-5 THz. To date, almost every type of material has been studied using THz TDS, including semiconductors, ceramics, polymers, metal films, liquid crystals, glasses, pharmaceuticals, DNA molecules, proteins, gases, composites, foams, oils, and many others. Measurements with a TDS are made in the time domain; conversion from the time domain data to a frequency spectrum is achieved by applying the Fourier Transform, calculated numerically using the Fast Fourier Transform (FFT) algorithm. As in many other types of spectrometer, THz TDS requires that the sample data be referenced to similarly acquired data with no sample present. Unlike frequency-domain spectrometers which detect light intensity and measure absorption spectra, a TDS records both amplitude and phase information, and therefore yields both the absorption coefficient and the refractive index of the sample material. The analysis of the data from THz TDS relies on the assumptions that: a) the frequency scale is accurate; b) the measurement of THz field amplitude is linear; and c) that the presence of the sample does not affect the performance characteristics of the instrument. The frequency scale of a THz TDS is derived from the displacement of the delay line; via FFT, positioning errors may give rise to frequency errors that are difficult to quantify. The measurement of the field amplitude in a THz TDS is required to be linear with a dynamic range of the order of 10 000. And attention must be given to the sample positioning and handling in order to avoid sample-related errors.

Statistical and population genetics issues of two Hungarian datasets from the aspect of DNA evidence interpretation.

PubMed

Szabolcsi, Zoltán; Farkas, Zsuzsa; Borbély, Andrea; Bárány, Gusztáv; Varga, Dániel; Heinrich, Attila; Völgyi, Antónia; Pamjav, Horolma

2015-11-01

When the DNA profile from a crime-scene matches that of a suspect, the weight of DNA evidence depends on the unbiased estimation of the match probability of the profiles. For this reason, it is required to establish and expand the databases that reflect the actual allele frequencies in the population applied. 21,473 complete DNA profiles from Databank samples were used to establish the allele frequency database to represent the population of Hungarian suspects. We used fifteen STR loci (PowerPlex ESI16) including five, new ESS loci. The aim was to calculate the statistical, forensic efficiency parameters for the Databank samples and compare the newly detected data to the earlier report. The population substructure caused by relatedness may influence the frequency of profiles estimated. As our Databank profiles were considered non-random samples, possible relationships between the suspects can be assumed. Therefore, population inbreeding effect was estimated using the FIS calculation. The overall inbreeding parameter was found to be 0.0106. Furthermore, we tested the impact of the two allele frequency datasets on 101 randomly chosen STR profiles, including full and partial profiles. The 95% confidence interval estimates for the profile frequencies (pM) resulted in a tighter range when we used the new dataset compared to the previously published ones. We found that the FIS had less effect on frequency values in the 21,473 samples than the application of minimum allele frequency. No genetic substructure was detected by STRUCTURE analysis. Due to the low level of inbreeding effect and the high number of samples, the new dataset provides unbiased and precise estimates of LR for statistical interpretation of forensic casework and allows us to use lower allele frequencies. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A novel 3D Cartesian random sampling strategy for Compressive Sensing Magnetic Resonance Imaging.

PubMed

Valvano, Giuseppe; Martini, Nicola; Santarelli, Maria Filomena; Chiappino, Dante; Landini, Luigi

2015-01-01

In this work we propose a novel acquisition strategy for accelerated 3D Compressive Sensing Magnetic Resonance Imaging (CS-MRI). This strategy is based on a 3D cartesian sampling with random switching of the frequency encoding direction with other K-space directions. Two 3D sampling strategies are presented. In the first strategy, the frequency encoding direction is randomly switched with one of the two phase encoding directions. In the second strategy, the frequency encoding direction is randomly chosen between all the directions of the K-Space. These strategies can lower the coherence of the acquisition, in order to produce reduced aliasing artifacts and to achieve a better image quality after Compressive Sensing (CS) reconstruction. Furthermore, the proposed strategies can reduce the typical smoothing of CS due to the limited sampling of high frequency locations. We demonstrated by means of simulations that the proposed acquisition strategies outperformed the standard Compressive Sensing acquisition. This results in a better quality of the reconstructed images and in a greater achievable acceleration.

Studies on frequency dependent electrical and dielectric properties of sintered zinc oxide pellets: effects of Al-doping

NASA Astrophysics Data System (ADS)

Tewari, S.; Ghosh, A.; Bhattacharjee, A.

2016-11-01

Sintered pellets of zinc oxide (ZnO), both undoped and Al-doped are prepared through a chemical process. Dopant concentration of Aluminium in ZnO [Al/Zn in weight percentage (wt%)] is varied from 0 to 3 wt%. After synthesis structural characterisation of the samples are performed with XRD and SEM-EDAX which confirm that all the samples are of ZnO having polycrystalline nature with particle size from 108.6 to 116 nm. Frequency dependent properties like a.c. conductivity, capacitance, impedance and phase angle are measured in the frequency range 10 Hz to 100 kHz as a function of temperature (in the range 25-150 °C). Nature of a.c. conductivity in these samples indicates hopping type of conduction arising from localised defect states. The frequency and temperature dependent properties under study are found to be as per correlated barrier hoping model. Dielectric and impedance properties studied in the samples indicate distributed relaxation, showing decrease of relaxation time with temperature.

Resonant ultrasound spectrometer

DOEpatents

Migliori, Albert; Visscher, William M.; Fisk, Zachary

1990-01-01

An ultrasound resonant spectrometer determines the resonant frequency spectrum of a rectangular parallelepiped sample of a high dissipation material over an expected resonant response frequency range. A sample holder structure grips corners of the sample between piezoelectric drive and receive transducers. Each transducer is mounted on a membrane for only weakly coupling the transducer to the holder structure and operatively contacts a material effective to remove system resonant responses at the transducer from the expected response range. i.e., either a material such as diamond to move the response frequencies above the range or a damping powder to preclude response within the range. A square-law detector amplifier receives the response signal and retransmits the signal on an isolated shield of connecting cabling to remove cabling capacitive effects. The amplifier also provides a substantially frequency independently voltage divider with the receive transducer. The spectrometer is extremely sensitive to enable low amplitude resonance to be detected for use in calculating the elastic constants of the high dissipation sample.

An experimental study of the effects of water repellant treatment on the acoustic properties of Kevlar

NASA Technical Reports Server (NTRS)

Smith, C. D.; Parrott, T. L.

1978-01-01

The treatment consisted of immersing samples of Kevlar in a solution of distilled water and Zepel. The samples were then drained, dried in a circulating over, and cured. Flow resistance tests showed approximately one percent decrease in flow resistance of the samples. Also there was a density increase of about three percent. It was found that the treatment caused a change in the texture of the samples. There were significant changes in the acoustic properties of the treated Kevlar over the frequency range 0.5 to 3.5 kHz. In general it was found that the propagation constant and characteristic impedance increased with increasing frequency. The real and imaginary components of the propagation constant for the treated Kevlar exhibited a decrease of 8 to 12 percent relative to that for the untreated Kevlar at the higher frequencies. The magnitude of the reactance component of the characteristic impedance decreased by about 40 percent at the higher frequencies.

[Development of the soft independent modelling of class analogies model to discrimination Vibrio parahemolyticus by Smartongue].

PubMed

Huang, Jianfeng; Zhao, Guangying; Dou, Wenchao

2011-04-01

To explore a new rapid detection method for detecting of Food pathogens. We used the Smartongue, to determine the composition informations of the liquid culture samples and combined with soft independent modelling of class analogies (SIMCA) to analyze their respective species, then set up a Smartongue -SIMCA model to discriminate the V. parahaemolyticus. The Smartongue has 6 working electrodes and three frequency segments, we can built 18 discrimination models in one detection. After comparing all the 18 discrimination models, the optimal working electrodes and frequency segments were selected out, they were: palladium electrode in 1 Hz frequency segment, tungsten electrode in 100 Hz and silver electrode in 100 Hz. Then 10 species of pathogenic Vibrio were discriminated by the 3 models. The V. damsela, V. metschnikovii, V. alginalyticus, V. cincinnatiensis, V. metschnikovii and V. cholerae O serogroup samples could be discriminated by the SIMCA model of V. parahaemolyticus with palladium electrode 1 Hz frequency segment; V. mimicus and V. vulnincus samples could be discriminated by the SIMCA model of V. parahaemolyticus with tungsten electrode 100 Hz frequency segment; V. carcariae and V. cholerae non-O serogroup samples could be discriminated with the SIMCA model of V. parahaemolyticus in silver electrode 100 Hz frequency segment. The accurate discrimination of ten species of Vibrio samples is 100%. The Smartongue combined with SIMCA can discriminate V. parahaemolyticus with other pathogenic Vibrio effectively. It has a promising future as a new rapid detection method for V. parahaemolyticus.

AC conduction of Ba1-xCaxTiO3 and BZT-BCTx

NASA Astrophysics Data System (ADS)

Khien, Nguyen Van; Huy, Than Trong; Hong, Le Van

2018-03-01

Ba1-xCaxTiO3 (BCTx), (x =0.0-0.3) and Ba0.8Zr0.2TiO3-Ba1-xCaxTiO3 (BZT-BCTx), (x=0.15-0.35) were fabricated by the solid state reaction method. Phase structure of the material samples was identified by X-ray diffraction. The impedance versus frequency in a range of 100 Hz to 2.5 MHz was measured for all the samples at room temperature. AC conductivity versus frequency of the BCTx and BZT-BCTx was evaluated and fitted by using the extended Universal Dielectric Response (UDR) equations. The fitting results were discussed in detail and shown that the localized reorientation polarization-based mechanism is most contributed in BCTx matrial samples. Basically both two the hopping polaron and polarization mechanisms play roles in BZT-BCTx material samples. In contrary the short-range polaron hopping is dominated in ac conductivity of BZT-BCTx material samples in low frequency range.

300 Area treated effluent disposal facility sampling schedule. Revision 1

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

Loll, C.M.

1995-03-28

This document is the interface between the 300 Area liquid effluent process engineering (LEPE) group and the waste sampling and characterization facility (WSCF), concerning process control samples. It contains a schedule for process control samples at the 300 Area TEDF which describes the parameters to be measured, the frequency of sampling and analysis, the sampling point, and the purpose for each parameter.

Apparatus configured for identification of a material and method of identifying a material

DOEpatents

Slater, John M.; Crawford, Thomas M.; Frickey, Dean A.

2001-01-01

The present invention relates to an apparatus configured for identification of a material and method of identifying a material. One embodiment of the present invention provides an apparatus configured for identification of a material including a first region configured to receive a first sample and output a first spectrum responsive to exposure of the first sample to radiation; a signal generator configured to provide a reference signal having a reference frequency and a modulation signal having a modulation frequency; a modulator configured to selectively modulate the first spectrum using the modulation signal according to the reference frequency; a second region configured to receive a second sample and output a second spectrum responsive to exposure of the second sample to the first spectrum; and a detector configured to detect the second spectrum.

Influence of color on dielectric properties of marinated poultry breast meat.

PubMed

Samuel, D; Trabelsi, S

2012-08-01

The dielectric behavior of foods when exposed to radio-frequency and microwave electric fields is highly influenced by moisture content and the degree of water binding with constituents of the food materials. The ability to correlate specific food quality characteristics with the dielectric properties can lead to the development of rapid, nondestructive techniques for such quality measurements. Water-holding capacity is a critical attribute in meat quality. Up to 50% of raw poultry meat in the United States is marinated with mixtures of water, salts, and phosphates. The objective of this study was to determine if variations in breast meat color would affect the dielectric properties of marinated poultry meat over a broad frequency range from 500 MHz to 50 GHz. Poultry meat was obtained from a local commercial plant in Georgia (USA). Color and pH measurements were taken on the breast filets. Groups of breast filets were sorted into classes of pale and normal before adding marination pickup percentages of 0, 5, 10, and 15. Breast filets were vacuum-tumbled and weighed for pickup percentages. Dielectric properties of the filets were measured with a coaxial open-ended probe on samples equilibrated to 25°C. Samples from pale meat exhibited higher dielectric properties than samples from normal meat. No differences could be observed between samples from pale and normal meat after marination of the samples. Overall, dielectric properties increased as the marination pickup increased (α=0.05). Marination pickup strongly influenced the dielectric loss factor. Differences between samples marinated at different pickup levels were more pronounced at lower frequencies for the dielectric loss factor. As frequency increased, the differences between samples decreased. Differences in dielectric constant between samples were not as consistent as those seen with the dielectric loss factor.

Frequency-time coherence for all-optical sampling without optical pulse source

PubMed Central

Preußler, Stefan; Raoof Mehrpoor, Gilda; Schneider, Thomas

2016-01-01

Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift. PMID:27687495

Using Computer Graphics in Statistics.

ERIC Educational Resources Information Center

Kerley, Lyndell M.

1990-01-01

Described is software which allows a student to use simulation to produce analytical output as well as graphical results. The results include a frequency histogram of a selected population distribution, a frequency histogram of the distribution of the sample means, and test the normality distributions of the sample means. (KR)

Frequency of Propionibacterium acnes Infection in Prostate Glands with Negative Biopsy Results Is an Independent Risk Factor for Prostate Cancer in Patients with Increased Serum PSA Titers.

PubMed

Kakegawa, Tomoya; Bae, Yuan; Ito, Takashi; Uchida, Keisuke; Sekine, Masaki; Nakajima, Yutaka; Furukawa, Asuka; Suzuki, Yoshimi; Kumagai, Jiro; Akashi, Takumi; Eishi, Yoshinobu

2017-01-01

Propionibacterium acnes has recently been implicated as a cause of chronic prostatitis and this commensal bacterium may be linked to prostate carcinogenesis. The occurrence of intracellular P. acnes infection in prostate glands and the higher frequency of P. acnes-positive glands in radical prostatectomy specimens from patients with prostate cancer (PCa) than in those from patients without PCa led us to examine whether the P. acnes-positive gland frequency can be used to assess the risk for PCa in patients whose first prostate biopsy, performed due to an increased prostate-specific antigen (PSA) titer, was negative. We retrospectively collected the first and last prostate biopsy samples from 44 patients that were diagnosed PCa within 4 years after the first negative biopsy and from 36 control patients with no PCa found in repeated biopsy for at least 3 years after the first biopsy. We evaluated P. acnes-positive gland frequency and P. acnes-positive macrophage number using enzyme-immunohistochemistry with a P. acnes-specific monoclonal antibody (PAL antibody). The frequency of P. acnes-positive glands was higher in PCa samples than in control samples in both first biopsy samples and in combined first and last biopsy samples (P < 0.001). A frequency greater than the threshold (18.5 and 17.7, respectively) obtained by each receiver operating characteristic curve was an independent risk factor for PCa (P = 0.003 and 0.001, respectively) with odds ratios (14.8 and 13.9, respectively) higher than those of serum PSA titers of patients just before each biopsy (4.6 and 2.3, respectively). The number of P. acnes-positive macrophages did not differ significantly between PCa and control samples. These results suggested that the frequency of P. acnes-positive glands in the first negative prostate biopsy performed due to increased PSA titers can be supportive information for urologists in planning repeated biopsy or follow-up strategies.

A neural algorithm for the non-uniform and adaptive sampling of biomedical data.

PubMed

Mesin, Luca

2016-04-01

Body sensors are finding increasing applications in the self-monitoring for health-care and in the remote surveillance of sensitive people. The physiological data to be sampled can be non-stationary, with bursts of high amplitude and frequency content providing most information. Such data could be sampled efficiently with a non-uniform schedule that increases the sampling rate only during activity bursts. A real time and adaptive algorithm is proposed to select the sampling rate, in order to reduce the number of measured samples, but still recording the main information. The algorithm is based on a neural network which predicts the subsequent samples and their uncertainties, requiring a measurement only when the risk of the prediction is larger than a selectable threshold. Four examples of application to biomedical data are discussed: electromyogram, electrocardiogram, electroencephalogram, and body acceleration. Sampling rates are reduced under the Nyquist limit, still preserving an accurate representation of the data and of their power spectral densities (PSD). For example, sampling at 60% of the Nyquist frequency, the percentage average rectified errors in estimating the signals are on the order of 10% and the PSD is fairly represented, until the highest frequencies. The method outperforms both uniform sampling and compressive sensing applied to the same data. The discussed method allows to go beyond Nyquist limit, still preserving the information content of non-stationary biomedical signals. It could find applications in body sensor networks to lower the number of wireless communications (saving sensor power) and to reduce the occupation of memory. Copyright © 2016 Elsevier Ltd. All rights reserved.

A STUDY OF BROADBAND FARADAY ROTATION AND POLARIZATION BEHAVIOR OVER 1.3–10 GHz IN 36 DISCRETE RADIO SOURCES

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

Anderson, C. S.; Gaensler, B. M.; Feain, I. J., E-mail: craiga@physics.usyd.edu.au

We present a broadband polarization analysis of 36 discrete polarized radio sources over a very broad, densely sampled frequency band. Our sample was selected on the basis of polarization behavior apparent in narrowband archival data at 1.4 GHz: half the sample shows complicated frequency-dependent polarization behavior (i.e., Faraday complexity) at these frequencies, while half shows comparatively simple behavior (i.e., they appear Faraday simple ). We re-observed the sample using the Australia Telescope Compact Array in full polarization, with 6 GHz of densely sampled frequency coverage spanning 1.3–10 GHz. We have devised a general polarization modeling technique that allows us tomore » identify multiple polarized emission components in a source, and to characterize their properties. We detect Faraday complex behavior in almost every source in our sample. Several sources exhibit particularly remarkable polarization behavior. By comparing our new and archival data, we have identified temporal variability in the broadband integrated polarization spectra of some sources. In a number of cases, the characteristics of the polarized emission components, including the range of Faraday depths over which they emit, their temporal variability, spectral index, and the linear extent of the source, allow us to argue that the spectropolarimetric data encode information about the magneto-ionic environment of active galactic nuclei themselves. Furthermore, the data place direct constraints on the geometry and magneto-ionic structure of this material. We discuss the consequences of restricted frequency bands on the detection and interpretation of polarization structures, and the implications for upcoming spectropolarimetric surveys.« less

Somatic mutation frequencies in the stamen hairs of Tradescantia grown in soil samples from the Bikini Island.

PubMed

Ichikawa, S; Ishii, C

1991-02-01

Somatic pink mutation frequencies in the stamen hairs of Tradescantia BNL 02 clone grown for 76 days in two soil samples taken from the Bikini Island (where a hydrogen bomb explosion test had been conducted in 1954) were investigated. A significantly high mutation frequency (2.58 +/- 0.17 pink mutant events per 10(3) hairs or 1.34 +/- 0.09 pink mutant events per 10(4) hair-cell divisions) was observed for the plant grown in one of the two Bikini soil samples, as compared to the control plants (1.70 +/- 0.14 or 0.88 +/- 0.07, respectively) grown in the field soil of Saitama University. The soil sample which caused the significant increase in mutation frequency contained 6,880 +/- 330 mBq/g 137Cs, 62.5 +/- 4.4 mBq/g 60Co, and some other nuclides; a 150 microR/hr exposure rate being measured on the surface of the soil sample. The effective cumulative external exposures measured for the inflorescences of the plant grown in this soil sample averaged at most 60.8 mR, being too small to explain the significant elevation in mutation frequency observed. On the other hand, internal exposure due to uptake of radioactive nuclides was estimated to be 125 mrad (1.25 mGy) as an accumulated effective dose, mainly based on a gamma-spectrometrical analysis. However, it seemed highly likely that this value of internal exposure was a considerable underestimate, and the internal exposure was considered to be more significant than the external exposure.

Laboratory Investigation of the Effect of Water-Saturation on Seismic Wave Dispersion in Carbonates

NASA Astrophysics Data System (ADS)

Li, W.; Pyrak-Nolte, L. J.

2009-12-01

In subsurface rock, fluid content changes with time through natural causes or because of human interactions, such as extraction or sequestration of fluids. The ability to monitor, seismically, fluid migration in the subsurface requires an understanding of the effects that the degree of saturation and spatial distribution of fluids have on wave propagation in rock. In this study, we find that the seismic dispersion of a dry carbonate rock can be masked by saturating the sample. We used a laboratory mini-seismic array to monitor fluid invasion and withdrawal in a carbonate rock with fabric-controlled layering. Experiments were performed on prismatic samples of Austin Chalk measuring 50mm x 50mm x 100mm. The epoxy-sealed samples contained an inlet and an outlet port to enable fluid invasion/withdrawal along the long axis of the sample. Water was infused and withdrawn from the sample at a rate of 1ml/hr. The mini-seismic array consisted of a set of 12 piezoelectric contact transducers, each with a central frequency 1.0 MHz. Three compressional wave source-receiver pairs and three shear wave source-receiver pairs were used to probe along the length of the sample prior to invasion and during invasion and withdrawal of water from the sample. A pressure transducer was used to record the fluid pressure simultaneously with the full transmitted wave forms every 15-30 minutes. A wavelet analysis determined the effect of fluid invasion on velocity dispersion. We observed that the compressional wave dispersion was more sensitive to changes in saturation than the shear wave dispersion. When the sample was unsaturated, the high frequency components of the compressional wave (1.2MHz to 2MHz) had lower velocities (~ 2750m/s) than the low frequency components, which decrease monotonically from 2890 m/s for 0.2MHz to 1.2 MHz. As water infused the sample, the dispersion weakened. When the sample as fully saturated, the compressional wave velocity was frequency independent. The functional form of the dependence of the shear wave velocity on frequency is relatively constant with fluid saturation, but the magnitude of the velocity decreased (~35 m/s) with increasing saturation. From theoretical calculations, the shear modulus increased during water invasion and was independent of frequency. However, the changes in the Young’s modulus with water invasion depended on the frequency of observation. When 46.5ml was infused into the sample, the Young’s modulus interpreted from the high-frequency components (wavelength from 1.43mm to 2.4mm) increased 70%, while the modulus from the low-frequency components (wavelengths vary from 1.4cm to 3.4mm) increased between 20% and 55%. Interpreting seismic data to determine fluid saturation in rock with fabric-controlled layering requires an understanding of the seismic dispersion properties of the rock in addition to the ability of fluids on alter or mask the dispersion. Acknowledgments: The authors wish to acknowledge support of this work by the Geosciences Research Program, Office of Basic Energy Sciences US Department of Energy (DEFG02-97ER14785 08), by Exxon Mobil Upstream Research Company and the GeoMathematical Imaging Group at Purdue University.

An approach to the interpretation of Cole-Davidson and Cole-Cole dielectric functions

NASA Astrophysics Data System (ADS)

Iglesias, T. P.; Vilão, G.; Reis, João Carlos R.

2017-08-01

Assuming that a dielectric sample can be described by Debye's model at each frequency, a method based on Cole's treatment is proposed for the direct estimation at experimental frequencies of relaxation times and the corresponding static and infinite-frequency permittivities. These quantities and the link between dielectric strength and mean molecular dipole moment at each frequency could be useful to analyze dielectric relaxation processes. The method is applied to samples that follow a Cole-Cole or a Cole-Davidson dielectric function. A physical interpretation of these dielectric functions is proposed. The behavior of relaxation time with frequency can be distinguished between the two dielectric functions. The proposed method can also be applied to samples following a Navriliak-Negami or any other dielectric function. The dielectric relaxation of a nanofluid consisting of graphene nanoparticles dispersed in the oil squalane is reported and discussed within the novel framework.

Comparison effects and dielectric properties of different dose methylene-blue-doped hydrogels.

PubMed

Yalçın, O; Coşkun, R; Okutan, M; Öztürk, M

2013-08-01

The dielectric properties of methylene blue (MB)-doped hydrogels were investigated by impedance spectroscopy. The real part (ε') and the imaginary part (ε") of the complex dielectric constant and the energy loss tangent/dissipation factor (tan δ) were measured in the frequency range of 10 Hz to 100 MHz at room temperature for pH 5.5 value. Frequency variations of the resistance, the reactance, and the impedance of the samples have also been investigated. The dielectric permittivity of the MB-doped hydrogels is sensitive to ionic conduction and electrode polarization in low frequency. Furthermore, the dielectric behavior in high-frequency parts was attributed to the Brownian motion of the hydrogen bonds. The ionic conduction for MB-doped samples was prevented for Cole-Cole plots, while the Cole-Cole plots for pure sample show equivalent electrical circuit. The alternative current (ac) conductivity increases with the increasing MB concentration and the frequency.

Allele frequencies for 12 autosomal short tandem repeat loci in two Bolivian populations.

PubMed

Cifuentes, L; Jorquera, H; Acuña, M; Ordóñez, J; Sierra, A L

2008-03-18

Two hundred and sixty unrelated subjects who asked for paternity testing at two Bolivian Laboratories in La Paz and Santa Cruz were studied. The loci D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, TH01, TPOX, and CSF1PO were typed from blood samples, amplifying DNA by polymerase chain reactions and electrophoresis. Allele frequencies were estimated by simple counting and the unbiased heterozygosity was calculated. Hardy-Weinberg equilibrium was studied and gene frequencies were compared between the two samples. All loci conformed to the Hardy-Weinberg law and allele frequencies were similar in samples from the two cities. The Bolivian gene frequencies estimated were significantly different from those described for Chile and the United States Hispanic-Americans for most of the loci.

High Accuracy Evaluation of the Finite Fourier Transform Using Sampled Data

NASA Technical Reports Server (NTRS)

Morelli, Eugene A.

1997-01-01

Many system identification and signal processing procedures can be done advantageously in the frequency domain. A required preliminary step for this approach is the transformation of sampled time domain data into the frequency domain. The analytical tool used for this transformation is the finite Fourier transform. Inaccuracy in the transformation can degrade system identification and signal processing results. This work presents a method for evaluating the finite Fourier transform using cubic interpolation of sampled time domain data for high accuracy, and the chirp Zeta-transform for arbitrary frequency resolution. The accuracy of the technique is demonstrated in example cases where the transformation can be evaluated analytically. Arbitrary frequency resolution is shown to be important for capturing details of the data in the frequency domain. The technique is demonstrated using flight test data from a longitudinal maneuver of the F-18 High Alpha Research Vehicle.

Numerical calculations of spectral turnover and synchrotron self-absorption in CSS and GPS radio sources

NASA Astrophysics Data System (ADS)

Jeyakumar, S.

2016-06-01

The dependence of the turnover frequency on the linear size is presented for a sample of Giga-hertz Peaked Spectrum and Compact Steep Spectrum radio sources derived from complete samples. The dependence of the luminosity of the emission at the peak frequency with the linear size and the peak frequency is also presented for the galaxies in the sample. The luminosity of the smaller sources evolve strongly with the linear size. Optical depth effects have been included to the 3D model for the radio source of Kaiser to study the spectral turnover. Using this model, the observed trend can be explained by synchrotron self-absorption. The observed trend in the peak-frequency-linear-size plane is not affected by the luminosity evolution of the sources.

A comparison of QuantStudio™ 3D Digital PCR and ARMS-PCR for measuring plasma EGFR T790M mutations of NSCLC patients.

PubMed

Feng, Qin; Gai, Fei; Sang, Yaxiong; Zhang, Jie; Wang, Ping; Wang, Yue; Liu, Bing; Lin, Dongmei; Yu, Yang; Fang, Jian

2018-01-01

The AURA3 clinical trial has shown that advanced non-small cell lung cancer (NSCLC) patients with EGFR T790M mutations in circulating tumor DNA (ctDNA) could benefit from osimertinib. The aim of this study was to assess the usefulness of QuantStudio™ 3D Digital PCR System platform for the detection of plasma EGFR T790M mutations in NSCLC patients, and compare the performances of 3D Digital PCR and ARMS-PCR. A total of 119 Chinese patients were enrolled in this study. Mutant allele frequency of plasma EGFR T790M was detected by 3D Digital PCR, then 25 selected samples were verified by ARMS-PCR and four of them were verified by next generation sequencing (NGS). In total, 52.94% (69/119) had EGFR T790M mutations detected by 3D Digital PCR. In 69 positive samples, the median mutant allele frequency (AF) was 1.09% and three cases presented low concentration (AF <0.1%). Limited by the amount of plasma DNA, 17 samples (AF <2.5%) and eight samples (T790M-) were selected for verification by ARMS-PCR. Four of those samples were verified by NGS as a third verification method. Among the selected 17 positive cases, ten samples presented mutant allele frequency <0.5%, and seven samples presented intermediate mutant allele frequency (0.5% AF 2.5%). However, only three samples (3/17) were identified as positive by ARMS-PCR, namely, P6 (AF =1.09%), P7 (AF =2.09%), and P8 (AF =2.21%). It is worth mentioning that sample P9 (AF =2.05%, analyzed by 3D Digital PCR) was identified as T790M- by ARMS-PCR. Four samples were identified as T790M+ by both NGS and 3D Digital PCR, and typically three samples (3/4) presented at a low ratio (AF <0.5%). Our study demonstrated that 3D Digital PCR is a novel method with high sensitivity and specificity to detect EGFR T790M mutation in plasma.

A comparison of QuantStudio™ 3D Digital PCR and ARMS-PCR for measuring plasma EGFR T790M mutations of NSCLC patients

PubMed Central

Sang, Yaxiong; Zhang, Jie; Wang, Ping; Wang, Yue; Liu, Bing; Lin, Dongmei; Yu, Yang; Fang, Jian

2018-01-01

Background The AURA3 clinical trial has shown that advanced non-small cell lung cancer (NSCLC) patients with EGFR T790M mutations in circulating tumor DNA (ctDNA) could benefit from osimertinib. Purpose The aim of this study was to assess the usefulness of QuantStudio™ 3D Digital PCR System platform for the detection of plasma EGFR T790M mutations in NSCLC patients, and compare the performances of 3D Digital PCR and ARMS-PCR. Patients and methods A total of 119 Chinese patients were enrolled in this study. Mutant allele frequency of plasma EGFR T790M was detected by 3D Digital PCR, then 25 selected samples were verified by ARMS-PCR and four of them were verified by next generation sequencing (NGS). Results In total, 52.94% (69/119) had EGFR T790M mutations detected by 3D Digital PCR. In 69 positive samples, the median mutant allele frequency (AF) was 1.09% and three cases presented low concentration (AF <0.1%). Limited by the amount of plasma DNA, 17 samples (AF <2.5%) and eight samples (T790M-) were selected for verification by ARMS-PCR. Four of those samples were verified by NGS as a third verification method. Among the selected 17 positive cases, ten samples presented mutant allele frequency <0.5%, and seven samples presented intermediate mutant allele frequency (0.5% AF 2.5%). However, only three samples (3/17) were identified as positive by ARMS-PCR, namely, P6 (AF =1.09%), P7 (AF =2.09%), and P8 (AF =2.21%). It is worth mentioning that sample P9 (AF =2.05%, analyzed by 3D Digital PCR) was identified as T790M- by ARMS-PCR. Four samples were identified as T790M+ by both NGS and 3D Digital PCR, and typically three samples (3/4) presented at a low ratio (AF <0.5%). Conclusion Our study demonstrated that 3D Digital PCR is a novel method with high sensitivity and specificity to detect EGFR T790M mutation in plasma. PMID:29403309

On the Berry-Esséen bound of frequency polygons for ϕ-mixing samples.

PubMed

Huang, Gan-Ji; Xing, Guodong

2017-01-01

Under some mild assumptions, the Berry-Esséen bound of frequency polygons for ϕ -mixing samples is presented. By the bound derived, we obtain the corresponding convergence rate of uniformly asymptotic normality, which is nearly [Formula: see text] under the given conditions.

Calibration of high frequency pollen sequences and tree-ring records

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

Wigand, P.E.; Rose, M.R.

This paper examines two radiocarbon dated paleoenvironmental records from southern Nevada for the possibility of correlating high-frequency pollen samples with nearby long-term tree-ring sequences. Variable deposition rate are discussed. Radiocarbon dating control of the pollen cores, as well as closer interval sampling is presented.

Investigation of rare and low-frequency variants using high-throughput sequencing with pooled DNA samples

PubMed Central

Wang, Jingwen; Skoog, Tiina; Einarsdottir, Elisabet; Kaartokallio, Tea; Laivuori, Hannele; Grauers, Anna; Gerdhem, Paul; Hytönen, Marjo; Lohi, Hannes; Kere, Juha; Jiao, Hong

2016-01-01

High-throughput sequencing using pooled DNA samples can facilitate genome-wide studies on rare and low-frequency variants in a large population. Some major questions concerning the pooling sequencing strategy are whether rare and low-frequency variants can be detected reliably, and whether estimated minor allele frequencies (MAFs) can represent the actual values obtained from individually genotyped samples. In this study, we evaluated MAF estimates using three variant detection tools with two sets of pooled whole exome sequencing (WES) and one set of pooled whole genome sequencing (WGS) data. Both GATK and Freebayes displayed high sensitivity, specificity and accuracy when detecting rare or low-frequency variants. For the WGS study, 56% of the low-frequency variants in Illumina array have identical MAFs and 26% have one allele difference between sequencing and individual genotyping data. The MAF estimates from WGS correlated well (r = 0.94) with those from Illumina arrays. The MAFs from the pooled WES data also showed high concordance (r = 0.88) with those from the individual genotyping data. In conclusion, the MAFs estimated from pooled DNA sequencing data reflect the MAFs in individually genotyped samples well. The pooling strategy can thus be a rapid and cost-effective approach for the initial screening in large-scale association studies. PMID:27633116

Interaction of surface plasmon polaritons in heavily doped GaN microstructures with terahertz radiation

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

Melentev, G. A., E-mail: gamelen@spbstu.ru; Shalygin, V. A.; Vorobjev, L. E.

2016-03-07

We present the results of experimental and theoretical studies of the surface plasmon polariton excitations in heavily doped GaN epitaxial layers. Reflection and emission of radiation in the frequency range of 2–20 THz including the Reststrahlen band were investigated for samples with grating etched on the sample surface, as well as for samples with flat surface. The reflectivity spectrum for p-polarized radiation measured for the sample with the surface-relief grating demonstrates a set of resonances associated with excitations of different surface plasmon polariton modes. Spectral peculiarities due to the diffraction effect have been also revealed. The characteristic features of themore » reflectivity spectrum, namely, frequencies, amplitudes, and widths of the resonance dips, are well described theoretically by a modified technique of rigorous coupled-wave analysis of Maxwell equations. The emissivity spectra of the samples were measured under epilayer temperature modulation by pulsed electric field. The emissivity spectrum of the sample with surface-relief grating shows emission peaks in the frequency ranges corresponding to the decay of the surface plasmon polariton modes. Theoretical analysis based on the blackbody-like radiation theory well describes the main peculiarities of the observed THz emission.« less

Spectral refractive index assessment of turbid samples by combining spatial frequency near-infrared spectroscopy with Kramers-Kronig analysis

NASA Astrophysics Data System (ADS)

Meitav, Omri; Shaul, Oren; Abookasis, David

2018-03-01

A practical algorithm for estimating the wavelength-dependent refractive index (RI) of a turbid sample in the spatial frequency domain with the aid of Kramers-Kronig (KK) relations is presented. In it, phase-shifted sinusoidal patterns (structured illumination) are serially projected at a high spatial frequency onto the sample surface (mouse scalp) at different near-infrared wavelengths while a camera mounted normally to the sample surface captures the reflected diffuse light. In the offline analysis pipeline, recorded images at each wavelength are converted to spatial absorption maps by logarithmic function, and once the absorption coefficient information is obtained, the imaginary part (k) of the complex RI (CRI), based on Maxell's equations, can be calculated. Using the data represented by k, the real part of the CRI (n) is then resolved by KK analysis. The wavelength dependence of n ( λ ) is then fitted separately using four standard dispersion models: Cornu, Cauchy, Conrady, and Sellmeier. In addition, three-dimensional surface-profile distribution of n is provided based on phase profilometry principles and a phase-unwrapping-based phase-derivative-variance algorithm. Experimental results demonstrate the capability of the proposed idea for sample's determination of a biological sample's RI value.

Spectrally interleaved, comb-mode-resolved spectroscopy using swept dual terahertz combs

PubMed Central

Hsieh, Yi-Da; Iyonaga, Yuki; Sakaguchi, Yoshiyuki; Yokoyama, Shuko; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Araki, Tsutomu; Yasui, Takeshi

2014-01-01

Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10−7 in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy. PMID:24448604

The effect of beat frequency on eye movements during free viewing.

PubMed

Maróti, Emese; Knakker, Balázs; Vidnyánszky, Zoltán; Weiss, Béla

2017-02-01

External periodic stimuli entrain brain oscillations and affect perception and attention. It has been shown that background music can change oculomotor behavior and facilitate detection of visual objects occurring on the musical beat. However, whether musical beats in different tempi modulate information sampling differently during natural viewing remains to be explored. Here we addressed this question by investigating how listening to naturalistic drum grooves in two different tempi affects eye movements of participants viewing natural scenes on a computer screen. We found that the beat frequency of the drum grooves modulated the rate of eye movements: fixation durations were increased at the lower beat frequency (1.7Hz) as compared to the higher beat frequency (2.4Hz) and no music conditions. Correspondingly, estimated visual sampling frequency decreased as fixation durations increased with lower beat frequency. These results imply that slow musical beats can retard sampling of visual information during natural viewing by increasing fixation durations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Is 50 Hz high enough ECG sampling frequency for accurate HRV analysis?

PubMed

Mahdiani, Shadi; Jeyhani, Vala; Peltokangas, Mikko; Vehkaoja, Antti

2015-01-01

With the worldwide growth of mobile wireless technologies, healthcare services can be provided at anytime and anywhere. Usage of wearable wireless physiological monitoring system has been extensively increasing during the last decade. These mobile devices can continuously measure e.g. the heart activity and wirelessly transfer the data to the mobile phone of the patient. One of the significant restrictions for these devices is usage of energy, which leads to requiring low sampling rate. This article is presented in order to investigate the lowest adequate sampling frequency of ECG signal, for achieving accurate enough time domain heart rate variability (HRV) parameters. For this purpose the ECG signals originally measured with high 5 kHz sampling rate were down-sampled to simulate the measurement with lower sampling rate. Down-sampling loses information, decreases temporal accuracy, which was then restored by interpolating the signals to their original sampling rates. The HRV parameters obtained from the ECG signals with lower sampling rates were compared. The results represent that even when the sampling rate of ECG signal is equal to 50 Hz, the HRV parameters are almost accurate with a reasonable error.

[Prevalence of Variants in the Apolipoprotein E (APOE) Gene in a General Population of Adults from an Urban Area of Medellin (Antioquia)].

PubMed

Arango Viana, Juan Carlos; Valencia, Ana Victoria; Páez, Ana Lucía; Montoya Gómez, Nilton; Palacio, Carlos; Arbeláez, María Patricia; Bedoya Berrío, Gabriel; García Valencia, Jenny

2014-01-01

To determine the allelic and genotype frequencies of apolipoproteine E (APOE) gene in a representative sample of the adult population of Medellin in 2010. A representative sample of the adult population of Medellin, was obtained by means of a multi-stage, stratified, conglomerate based sampling method. APOE genotyping was carried out on each of the participants. The sampling design was taken into consideration for the frequencies and association analysis. The frequencies of the APOE alleles E2, E3 and E4 were 3.9, 92.0 and 4.1%, respectively. The frequencies of the different APOE genotypes were as follows: 2/2, 0.2%; 2/3, 6.8%; 2/4, 0.6%; 3/3, 85.0%; 3/4, 7.2%, and 4/4, 0.3%. The allelic and genotype frequencies of APOE in an adult population of Medellin did not differ substantially from other series reported in South America. These data are important to determine the real impact of APOE on the population risk of several psychiatric diseases. Copyright © 2013 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

Magnetostrictive resonance excitation

DOEpatents

Schwarz, Ricardo B.; Kuokkala, Veli-Tapani

1992-01-01

The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

The estimation of tree posterior probabilities using conditional clade probability distributions.

PubMed

Larget, Bret

2013-07-01

In this article I introduce the idea of conditional independence of separated subtrees as a principle by which to estimate the posterior probability of trees using conditional clade probability distributions rather than simple sample relative frequencies. I describe an algorithm for these calculations and software which implements these ideas. I show that these alternative calculations are very similar to simple sample relative frequencies for high probability trees but are substantially more accurate for relatively low probability trees. The method allows the posterior probability of unsampled trees to be calculated when these trees contain only clades that are in other sampled trees. Furthermore, the method can be used to estimate the total probability of the set of sampled trees which provides a measure of the thoroughness of a posterior sample.

Hanford Site Environmental Surveillance Master Sampling Schedule for Calendar Year 2007

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

Bisping, Lynn E.

2007-01-31

This document contains the calendar year 2007 schedule for the routine collection of samples for the Surface Environmental Surveillance Project and Drinking Water Monitoring Project. Each section includes sampling locations, sampling frequencies, sample types, and analyses to be performed. In some cases, samples are scheduled on a rotating basis and may not be collected in 2007 in which case the anticipated year for collection is provided. Maps showing approximate sampling locations are included for media scheduled for collection in 2007.

Effects of Ti doping on the dielectric properties of HfO{sub 2} nanoparticles

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

Pokhriyal, S.; Biswas, S., E-mail: drsomnathbiswas@gmail.com

2016-05-06

We report the effects of Ti doping on the dielectric properties of HfO{sub 2} [Hf{sub 1-x}Ti{sub x}O{sub 2} (x = 0.2-0.8)] nanoparticles at room temperature. The Hf{sub 1-x}Ti{sub x}O{sub 2} nanoparticles were synthesized by a wet chemical process. The structural and morphological properties of the derived samples were analyzed with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and high resolution transmission electron microscopy (HRTEM). Impedance analysis was performed in pelletized samples in the frequency range of 1 MHz to 1 GHz. The obtained results were analyzed in correlation with microstructure and doping concentration in the derived samples. The averagemore » size of the Hf{sub 1-x}Ti{sub x}O{sub 2} nanoparticles is typically in the range of 4-8 nm depending on the processing temperature. The Hf{sub 1−x}Ti{sub x}O{sub 2} nanoparticles show reduction in crystallinity with the increase in Ti doping. The dielectric constants of the derived samples decrease with the increase in frequency. The ac-conductivity in the samples increases with the increase in frequency irrespective of Ti concentration and shows significant drop with the increase in Ti concentration at all frequencies.« less

Sampling maternal care behaviour in domestic dogs: What's the best approach?

PubMed

Czerwinski, Veronika H; Smith, Bradley P; Hynd, Philip I; Hazel, Susan J

2017-07-01

Our understanding of the frequency and duration of maternal care behaviours in the domestic dog during the first two postnatal weeks is limited, largely due to the inconsistencies in the sampling methodologies that have been employed. In order to develop a more concise picture of maternal care behaviour during this period, and to help establish the sampling method that represents these behaviours best, we compared a variety of time sampling methods Six litters were continuously observed for a total of 96h over postnatal days 3, 6, 9 and 12 (24h per day). Frequent (dam presence, nursing duration, contact duration) and infrequent maternal behaviours (anogenital licking duration and frequency) were coded using five different time sampling methods that included: 12-h night (1800-0600h), 12-h day (0600-1800h), one hour period during the night (1800-0600h), one hour period during the day (0600-1800h) and a one hour period anytime. Each of the one hour time sampling method consisted of four randomly chosen 15-min periods. Two random sets of four 15-min period were also analysed to ensure reliability. We then determined which of the time sampling methods averaged over the three 24-h periods best represented the frequency and duration of behaviours. As might be expected, frequently occurring behaviours were adequately represented by short (oneh) sampling periods, however this was not the case with the infrequent behaviour. Thus, we argue that the time sampling methodology employed must match the behaviour of interest. This caution applies to maternal behaviour in altricial species, such as canids, as well as all systematic behavioural observations utilising time sampling methodology. Copyright © 2017. Published by Elsevier B.V.

50 CFR 648.90 - NE multispecies assessment, framework procedures and specifications, and flexible area action...

Code of Federal Regulations, 2012 CFR

2012-10-01

...; survey results; stock status; current estimates of fishing mortality and overfishing levels; social and... survey data or, if sea sampling data are unavailable, length frequency information from trawl surveys... size; sea sampling, port sampling, and survey data or, if sea sampling data are unavailable, length...

Color and Vector Flow Imaging in Parallel Ultrasound With Sub-Nyquist Sampling.

PubMed

Madiena, Craig; Faurie, Julia; Poree, Jonathan; Garcia, Damien; Garcia, Damien; Madiena, Craig; Faurie, Julia; Poree, Jonathan

2018-05-01

RF acquisition with a high-performance multichannel ultrasound system generates massive data sets in short periods of time, especially in "ultrafast" ultrasound when digital receive beamforming is required. Sampling at a rate four times the carrier frequency is the standard procedure since this rule complies with the Nyquist-Shannon sampling theorem and simplifies quadrature sampling. Bandpass sampling (or undersampling) outputs a bandpass signal at a rate lower than the maximal frequency without harmful aliasing. Advantages over Nyquist sampling are reduced storage volumes and data workflow, and simplified digital signal processing tasks. We used RF undersampling in color flow imaging (CFI) and vector flow imaging (VFI) to decrease data volume significantly (factor of 3 to 13 in our configurations). CFI and VFI with Nyquist and sub-Nyquist samplings were compared in vitro and in vivo. The estimate errors due to undersampling were small or marginal, which illustrates that Doppler and vector Doppler images can be correctly computed with a drastically reduced amount of RF samples. Undersampling can be a method of choice in CFI and VFI to avoid information overload and reduce data transfer and storage.

Noise and complexity in human postural control: interpreting the different estimations of entropy.

PubMed

Rhea, Christopher K; Silver, Tobin A; Hong, S Lee; Ryu, Joong Hyun; Studenka, Breanna E; Hughes, Charmayne M L; Haddad, Jeffrey M

2011-03-17

Over the last two decades, various measures of entropy have been used to examine the complexity of human postural control. In general, entropy measures provide information regarding the health, stability and adaptability of the postural system that is not captured when using more traditional analytical techniques. The purpose of this study was to examine how noise, sampling frequency and time series length influence various measures of entropy when applied to human center of pressure (CoP) data, as well as in synthetic signals with known properties. Such a comparison is necessary to interpret data between and within studies that use different entropy measures, equipment, sampling frequencies or data collection durations. The complexity of synthetic signals with known properties and standing CoP data was calculated using Approximate Entropy (ApEn), Sample Entropy (SampEn) and Recurrence Quantification Analysis Entropy (RQAEn). All signals were examined at varying sampling frequencies and with varying amounts of added noise. Additionally, an increment time series of the original CoP data was examined to remove long-range correlations. Of the three measures examined, ApEn was the least robust to sampling frequency and noise manipulations. Additionally, increased noise led to an increase in SampEn, but a decrease in RQAEn. Thus, noise can yield inconsistent results between the various entropy measures. Finally, the differences between the entropy measures were minimized in the increment CoP data, suggesting that long-range correlations should be removed from CoP data prior to calculating entropy. The various algorithms typically used to quantify the complexity (entropy) of CoP may yield very different results, particularly when sampling frequency and noise are different. The results of this study are discussed within the context of the neural noise and loss of complexity hypotheses.

Enhancement of low sampling frequency recordings for ECG biometric matching using interpolation.

PubMed

Sidek, Khairul Azami; Khalil, Ibrahim

2013-01-01

Electrocardiogram (ECG) based biometric matching suffers from high misclassification error with lower sampling frequency data. This situation may lead to an unreliable and vulnerable identity authentication process in high security applications. In this paper, quality enhancement techniques for ECG data with low sampling frequency has been proposed for person identification based on piecewise cubic Hermite interpolation (PCHIP) and piecewise cubic spline interpolation (SPLINE). A total of 70 ECG recordings from 4 different public ECG databases with 2 different sampling frequencies were applied for development and performance comparison purposes. An analytical method was used for feature extraction. The ECG recordings were segmented into two parts: the enrolment and recognition datasets. Three biometric matching methods, namely, Cross Correlation (CC), Percent Root-Mean-Square Deviation (PRD) and Wavelet Distance Measurement (WDM) were used for performance evaluation before and after applying interpolation techniques. Results of the experiments suggest that biometric matching with interpolated ECG data on average achieved higher matching percentage value of up to 4% for CC, 3% for PRD and 94% for WDM. These results are compared with the existing method when using ECG recordings with lower sampling frequency. Moreover, increasing the sample size from 56 to 70 subjects improves the results of the experiment by 4% for CC, 14.6% for PRD and 0.3% for WDM. Furthermore, higher classification accuracy of up to 99.1% for PCHIP and 99.2% for SPLINE with interpolated ECG data as compared of up to 97.2% without interpolation ECG data verifies the study claim that applying interpolation techniques enhances the quality of the ECG data. Crown Copyright © 2012. Published by Elsevier Ireland Ltd. All rights reserved.

Frequency of Extended-Spectrum Beta-lactamases (ESBLs) in strains of Klebsiella and E. coli isolated from patients hospitalized in Yazd.

PubMed

Zandi, Hengameh; Tabatabaei, Seyed Mostafa; Ehsani, Fatemeh; Zarch, Mojtaba Babaei; Doosthosseini, Samira

2017-02-01

Frequency of extended-spectrum beta-lactamases (ESBLs) and its variants may vary in different geographical areas, as reports indicate their spread in some certain communities. The aim of this study was to determine the frequency of ESBLs in strains of Klebsiella and E. coli , isolated from patients hospitalized in teaching hospitals of Yazd. This cross-sectional study was carried out on samples including E. coli and Klebsiella strains collected from laboratories of Shahid Sadoughi and Shahid Rahnemoun hospitals in Yazd, Iran in the period of 2011-2012. The colonies which were positive in lactose Eosin methylene-blue (EMB) medium were identified by biochemical methods, and 270 strains of Klebsiella and E. coli were isolated. Collected data and information were analyzed using Fisher's exact test and descriptive statistics such as mean in SPSS software, version 15, at a significant level of 0.05. In this study, 270 samples were examined, including 152 samples of E. coli (56.3%) and 118 samples of Klebsiella pneumonia (43.7%). Among the 152 samples of E. coli , 45 strains (30%) were producers of ESBLs. In addition, among the 118 samples of Klebsiella pneumonia , 44 strains (37.3%) were producers of ESBLs. E. coli strains showed the most resistance to Cefotaxime (100%), Ceftazidime (97.7%), and Cefepime (75.5%) respectively and Klebsiella strains showed the most resistance to Cefotaxime (100%), Ceftazidime (100%) and Cefepime (79.5%), respectively. Frequency of ESBLs in Klebsiella strains was higher than E. coli strains. No significant relationship was found between frequency of ESBLs and age or gender. In addition, E. coli strains showed the highest sensitivity to Imipenem, Amoxicillin/clavulanate, and Ciprofloxacin, while the highest antibiotic sensitivity of Klebsiella strains was shown to be to Piperacillin, Imipenem, and Amoxicillin/clavulanate.

76 FR 35923 - Notice of Opportunity for Public Comment on the Proposed Model Safety Evaluation for Plant...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-20

... Traveler TSTF-510, Revision 2, ``Revision to Steam Generator Program Inspection Frequencies and Tube Sample...-510, Revision 2, ``Revision to Steam Generator Program Inspection Frequencies and Tube Sample Selection.'' TSTF-510, Revision 2, is available in the Agencywide Documents Access and Management System...

Effect of water quality sampling time and frequency on storm load predictions of a prominent regression-based model

USDA-ARS?s Scientific Manuscript database

High frequency in situ measurements of nitrate can greatly reduce the uncertainty in nitrate flux estimates. Water quality databases maintained by various federal and state agencies often consist of pollutant concentration data obtained from periodic grab samples collected from gauged reaches of a s...

Soil, Groundwater, Surface Water, and Sediments of Kennedy Space Center, Florida: Background Chemical and Physical Characteristics

NASA Technical Reports Server (NTRS)

Shmalzer, Paul A.; Hensley, Melissa A.; Mota, Mario; Hall, Carlton R.; Dunlevy, Colleen A.

2000-01-01

This study documented background chemical composition of soils, groundwater, surface; water, and sediments of Kennedy Space Center. Two hundred soil samples were collected, 20 each in 10 soil classes. Fifty-one groundwater wells were installed in 4 subaquifers of the Surficial Aquifer and sampled; there were 24 shallow, 16 intermediate, and 11 deep wells. Forty surface water and sediment samples were collected in major watershed basins. All samples were away from sites of known contamination. Samples were analyzed for organochlorine pesticides, aroclors, chlorinated herbicides, polycyclic aromatic hydrocarbons (PAH), total metals, and other parameters. All aroclors (6) were below detection in all media. Some organochlorine pesticides were detected at very low frequencies in soil, sediment, and surface water. Chlorinated herbicides were detected at very low frequencies in soil and sediments. PAH occurred in low frequencies in soiL, shallow groundwater, surface water, and sediments. Concentrations of some metals differed among soil classes, with subaquifers and depths, and among watershed basins for surface water but not sediments. Most of the variation in metal concentrations was natural, but agriculture had increased Cr, Cu, Mn, and Zn.

Effects of Heterogeneities, Sampling Frequencies, Tools and Methods on Uncertainties in Subsurface Contaminant Concentration Measurements

NASA Astrophysics Data System (ADS)

Ezzedine, S. M.; McNab, W. W.

2007-12-01

Long-term monitoring (LTM) is particularly important for contaminants which are mitigated by natural processes of dilution, dispersion, and degradation. At many sites, LTM can require decades of expensive sampling at tens or even hundreds of existing monitoring wells, resulting in hundreds of thousands, or millions of dollars per year for sampling and data management. Therefore, contaminant sampling tools, methods and frequencies are chosen to minimize waste and data management costs while ensuring a reliable and informative time-history of contaminant measurement for regulatory compliance. The interplay play between cause (i.e. subsurface heterogeneities, sampling techniques, measurement frequencies) and effect (unreliable data and measurements gap) has been overlooked in many field applications which can lead to inconsistencies in time- histories of contaminant samples. In this study we address the relationship between cause and effect for different hydrogeological sampling settings: porous and fractured media. A numerical model has been developed using AMR-FEM to solve the physicochemical processes that take place in the aquifer and the monitoring well. In the latter, the flow is governed by the Navier-Stokes equations while in the former the flow is governed by the diffusivity equation; both are fully coupled to mimic stressed conditions and to assess the effect of dynamic sampling tool on the formation surrounding the monitoring well. First of all, different sampling tools (i.e., Easy Pump, Snapper Grab Sampler) were simulated in a monitoring well screened in different homogeneous layered aquifers to assess their effect on the sampling measurements. Secondly, in order to make the computer runs more CPU efficient the flow in the monitoring well was replaced by its counterpart flow in porous media with infinite permeability and the new model was used to simulate the effect of heterogeneities, sampling depth, sampling tool and sampling frequencies on the uncertainties in the concentration measurements. Finally, the models and results were abstracted using a simple mixed-tank approach to further simplify the models and make them more accessible to field hydrogeologists. During the abstraction process a novel method was developed for mapping streamlines in the fractures as well within the monitoring well to illustrate mixing and mixing zones. Applications will be demonstrated for both sampling in porous and fractured media. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

High frequency resolution terahertz time-domain spectroscopy

NASA Astrophysics Data System (ADS)

Sangala, Bagvanth Reddy

2013-12-01

A new method for the high frequency resolution terahertz time-domain spectroscopy is developed based on the characteristic matrix method. This method is useful for studying planar samples or stack of planar samples. The terahertz radiation was generated by optical rectification in a ZnTe crystal and detected by another ZnTe crystal via electro-optic sampling method. In this new characteristic matrix based method, the spectra of the sample and reference waveforms will be modeled by using characteristic matrices. We applied this new method to measure the optical constants of air. The terahertz transmission through the layered systems air-Teflon-air-Quartz-air and Nitrogen gas-Teflon-Nitrogen gas-Quartz-Nitrogen gas was modeled by the characteristic matrix method. A transmission coefficient is derived from these models which was optimized to fit the experimental transmission coefficient to extract the optical constants of air. The optimization of an error function involving the experimental complex transmission coefficient and the theoretical transmission coefficient was performed using patternsearch algorithm of MATLAB. Since this method takes account of the echo waveforms due to reflections in the layered samples, this method allows analysis of longer time-domain waveforms giving rise to very high frequency resolution in the frequency-domain. We have presented the high frequency resolution terahertz time-domain spectroscopy of air and compared the results with the literature values. We have also fitted the complex susceptibility of air to the Lorentzian and Gaussian functions to extract the linewidths.

A generative inference framework for analysing patterns of cultural change in sparse population data with evidence for fashion trends in LBK culture.

PubMed

Kandler, Anne; Shennan, Stephen

2015-12-06

Cultural change can be quantified by temporal changes in frequency of different cultural artefacts and it is a central question to identify what underlying cultural transmission processes could have caused the observed frequency changes. Observed changes, however, often describe the dynamics in samples of the population of artefacts, whereas transmission processes act on the whole population. Here we develop a modelling framework aimed at addressing this inference problem. To do so, we firstly generate population structures from which the observed sample could have been drawn randomly and then determine theoretical samples at a later time t2 produced under the assumption that changes in frequencies are caused by a specific transmission process. Thereby we also account for the potential effect of time-averaging processes in the generation of the observed sample. Subsequent statistical comparisons (e.g. using Bayesian inference) of the theoretical and observed samples at t2 can establish which processes could have produced the observed frequency data. In this way, we infer underlying transmission processes directly from available data without any equilibrium assumption. We apply this framework to a dataset describing pottery from settlements of some of the first farmers in Europe (the LBK culture) and conclude that the observed frequency dynamic of different types of decorated pottery is consistent with age-dependent selection, a preference for 'young' pottery types which is potentially indicative of fashion trends. © 2015 The Author(s).

Strelka: accurate somatic small-variant calling from sequenced tumor-normal sample pairs.

PubMed

Saunders, Christopher T; Wong, Wendy S W; Swamy, Sajani; Becq, Jennifer; Murray, Lisa J; Cheetham, R Keira

2012-07-15

Whole genome and exome sequencing of matched tumor-normal sample pairs is becoming routine in cancer research. The consequent increased demand for somatic variant analysis of paired samples requires methods specialized to model this problem so as to sensitively call variants at any practical level of tumor impurity. We describe Strelka, a method for somatic SNV and small indel detection from sequencing data of matched tumor-normal samples. The method uses a novel Bayesian approach which represents continuous allele frequencies for both tumor and normal samples, while leveraging the expected genotype structure of the normal. This is achieved by representing the normal sample as a mixture of germline variation with noise, and representing the tumor sample as a mixture of the normal sample with somatic variation. A natural consequence of the model structure is that sensitivity can be maintained at high tumor impurity without requiring purity estimates. We demonstrate that the method has superior accuracy and sensitivity on impure samples compared with approaches based on either diploid genotype likelihoods or general allele-frequency tests. The Strelka workflow source code is available at ftp://strelka@ftp.illumina.com/. csaunders@illumina.com

A portable system with sample rate of 250 Hz for characterization of knee and hip angles in the sagittal plane during gait

PubMed Central

2014-01-01

Background Gait analysis and research have been developed to obtain characteristics of movement patterns of people while walking. However, traditional measuring systems present different drawbacks that reduce their use and application. Among those drawbacks one can find: high price, low sampling frequency and limiting number of steps to be analyzed. Traditional measuring gait systems carry out their measurement at frequencies oscillating between 60 to 100 Hz. It can be argued about the need of higher sampling rates for gait measurements. However small displacements of the knee or hip for example, cannot be seen with low frequencies required a more detailed sampling and higher frequency sampling. Bearing this in mind, in this paper is presented a 250 Hz system based on accelerometers for gait measurement, and the particularities of knee and hip angles during gait are highlighted. Methods The system was designed with a PCI data acquisition card instrumented with an FPGA to achieve a rate sample of 250 Hz. The accelerometers were placed in thighs and legs to calculate the joint angles of hip and knee in the sagittal plane. The angles were estimated using the acceleration polygon method without integrating the acceleration and without filters. Results The gait of thirty healthy people of Mexican phenotype was analyzed over a flat floor free of obstacles. The results showed the gait phases and particularities associated with the walking style and people's laterality; the movement patterns were similar in the thirty persons. Based on the results, the particularities as the maximum amplitude in the angles and the shape in the movement patterns were related to the anthropometry and people phenotype. Conclusions The sampling frequency was essential to record 340 samples in single gait cycle and so registering the gait cycle with its particularities. In this work were recorded an average of 8 to 10 gait cycles, and the results showed variation regarding works carried out in biomechanics laboratories; this variation was related to the method and reference frame used to obtain the joint angles and the accuracy of measurement system. PMID:24684720

A portable system with sample rate of 250 Hz for characterization of knee and hip angles in the sagittal plane during gait.

PubMed

Martínez-Solís, Fermín; Claudio-Sánchez, Abraham; Rodríguez-Lelis, José M; Vergara-Limon, Sergio; Olivares-Peregrino, Víctor; Vargas-Treviño, Marciano

2014-03-31

Gait analysis and research have been developed to obtain characteristics of movement patterns of people while walking. However, traditional measuring systems present different drawbacks that reduce their use and application. Among those drawbacks one can find: high price, low sampling frequency and limiting number of steps to be analyzed. Traditional measuring gait systems carry out their measurement at frequencies oscillating between 60 to 100 Hz. It can be argued about the need of higher sampling rates for gait measurements. However small displacements of the knee or hip for example, cannot be seen with low frequencies required a more detailed sampling and higher frequency sampling. Bearing this in mind, in this paper is presented a 250 Hz system based on accelerometers for gait measurement, and the particularities of knee and hip angles during gait are highlighted. The system was designed with a PCI data acquisition card instrumented with an FPGA to achieve a rate sample of 250 Hz. The accelerometers were placed in thighs and legs to calculate the joint angles of hip and knee in the sagittal plane. The angles were estimated using the acceleration polygon method without integrating the acceleration and without filters. The gait of thirty healthy people of Mexican phenotype was analyzed over a flat floor free of obstacles. The results showed the gait phases and particularities associated with the walking style and people's laterality; the movement patterns were similar in the thirty persons. Based on the results, the particularities as the maximum amplitude in the angles and the shape in the movement patterns were related to the anthropometry and people phenotype. The sampling frequency was essential to record 340 samples in single gait cycle and so registering the gait cycle with its particularities. In this work were recorded an average of 8 to 10 gait cycles, and the results showed variation regarding works carried out in biomechanics laboratories; this variation was related to the method and reference frame used to obtain the joint angles and the accuracy of measurement system.

Automation of high-frequency sampling of environmental waters for reactive species

NASA Astrophysics Data System (ADS)

Kim, H.; Bishop, J. K.; Wood, T.; Fung, I.; Fong, M.

2011-12-01

Trace metals, particularly iron and manganese, play a critical role in some ecosystems as a limiting factor to determine primary productivity, in geochemistry, especially redox chemistry as important electron donors and acceptors, and in aquatic environments as carriers of contaminant transport. Dynamics of trace metals are closely related to various hydrologic events such as rainfall. Storm flow triggers dramatic changes of both dissolved and particulate trace metals concentrations and affects other important environmental parameters linked to trace metal behavior such as dissolved organic carbon (DOC). To improve our understanding of behaviors of trace metals and underlying processes, water chemistry information must be collected for an adequately long period of time at higher frequency than conventional manual sampling (e.g. weekly, biweekly). In this study, we developed an automated sampling system to document the dynamics of trace metals, focusing on Fe and Mn, and DOC for a multiple-year high-frequency geochemistry time series in a small catchment, called Rivendell located at Angelo Coast Range Reserve, California. We are sampling ground and streamwater using the automated sampling system in daily-frequency and the condition of the site is substantially variable from season to season. The ranges of pH of ground and streamwater are pH 5 - 7 and pH 7.8 - 8.3, respectively. DOC is usually sub-ppm, but during rain events, it increases by an order of magnitude. The automated sampling system focuses on two aspects- 1) a modified design of sampler to improve sample integrity for trace metals and DOC and 2) remote controlling system to update sampling volume and timing according to hydrological conditions. To maintain sample integrity, the developed method employed gravity filtering using large volume syringes (140mL) and syringe filters connected to a set of polypropylene bottles and a borosilicate bottle via Teflon tubing. Without filtration, in a few days, the dissolved concentration of Fe and Mn in the ground and streamwater samples stored in low density polyethylene (LDPE) sample bags decreased by 89% and 97%, respectively. In some cases of groundwater, the concentration of Ca decreased by 25%, due to degassing of CO2. However, DOC of the samples in LDPE bags without filtration increased up to 50% in 2 weeks, suggesting contamination from the bag. Performance of the new design was evaluated using the Fe-Mn-spiked Rivendell samples and environmental water samples collected from 1) Rivendell, 2) the Strawberry Creek located at the University of California, Berkeley campus, and 3) the San Francisco Bay. The samples were filtered using the developed method and stored in room temperature in 2 - 3 weeks without further treatment. The method improved the sample integrity significantly; the average recovery rates of Fe, Mn, DOC, and Ca were 92%, 98%, 90%, and 97%, respectively.

A system for measuring complex dielectric properties of thin films at submillimeter wavelengths using an open hemispherical cavity and a vector network analyzer.

PubMed

Rahman, Rezwanur; Taylor, P C; Scales, John A

2013-08-01

Quasi-optical (QO) methods of dielectric spectroscopy are well established in the millimeter and submillimeter frequency bands. These methods exploit standing wave structure in the sample produced by a transmitted Gaussian beam to achieve accurate, low-noise measurement of the complex permittivity of the sample [e.g., J. A. Scales and M. Batzle, Appl. Phys. Lett. 88, 062906 (2006); R. N. Clarke and C. B. Rosenberg, J. Phys. E 15, 9 (1982); T. M. Hirovnen, P. Vainikainen, A. Lozowski, and A. V. Raisanen, IEEE Trans. Instrum. Meas. 45, 780 (1996)]. In effect the sample itself becomes a low-Q cavity. On the other hand, for optically thin samples (films of thickness much less than a wavelength) or extremely low loss samples (loss tangents below 10(-5)) the QO approach tends to break down due to loss of signal. In such a case it is useful to put the sample in a high-Q cavity and measure the perturbation of the cavity modes. Provided that the average mode frequency divided by the shift in mode frequency is less than the Q (quality factor) of the mode, then the perturbation should be resolvable. Cavity perturbation techniques are not new, but there are technological difficulties in working in the millimeter/submillimeter wave region. In this paper we will show applications of cavity perturbation to the dielectric characterization of semi-conductor thin films of the type used in the manufacture of photovoltaics in the 100 and 350 GHz range. We measured the complex optical constants of hot-wire chemical deposition grown 1-μm thick amorphous silicon (a-Si:H) film on borosilicate glass substrate. The real part of the refractive index and dielectric constant of the glass-substrate varies from frequency-independent to linearly frequency-dependent. We also see power-law behavior of the frequency-dependent optical conductivity from 316 GHz (9.48 cm(-1)) down to 104 GHz (3.12 cm(-1)).

Experimental Evidence of Volcanic Earthquakes Induced by Different Fluid Types

NASA Astrophysics Data System (ADS)

Clarke, J. A.; Adam, L.; Sarout, J.; van Wijk, K.; Dautriat, J. D.; Kennedy, B.

2017-12-01

Low Frequency volcanic seismicity has long been associated with resonance in fluid-filled cracks or conduits driven by pressure perturbations at depth. In volcano monitoring, fluid movement, fracturing and the conduit geometry are interpreted based on field observations, laboratory experiments, and numerical models. Fluids in a volcanic environment include gasses, brine and magmas with different viscosities. Magma viscosity is a key influence on eruptive behaviour. For example, increasing magma viscosity is known to favour explosive eruptions. How different fluids affect volcano seismicity is not well understood. Here, we explore the effects of fluid type on volcano seismic signals. Frequency content in the signal, frequency of the events, source mechanism and quality factor are studied. We simulate volcano tectonic (fracturing) and volcano seismic (fluid movement) signatures in a controlled laboratory environment using a range of rock samples, fluid types and pressure conditions. The viscosity of the fluids spans six orders of magnitude, representing realistic volcanic fluids. Microseismicity is generated by venting pressurised fluids through pre-generated fracture networks in cylindrical rock core samples and detected by an array of 18 ultrasonic transducers. We fracture samples of two lithologies: 1) low porosity impermeable granite samples and 2) a permeable volcanic ash tuff sample. Permeability and porosity in the granites are due to a fracture network, while in the tuff a high porosity matrix ( 40 %) and a fracture network interact. The fluids used are nitrogen gas, water, and mixtures of water and glycerol. We generate and detect a myriad of seismic event types, some of which resemble well-known families of volcano-tectonic, low-frequency, hybrid and tremor-type seismicity. Samples with fluids of lower density and viscosity generate a higher number of seismic events. We will present an integrated analysis of the event types, frequency content, source locations and mechanisms. In addition, we explore the importance of seismic wave attenuation by studying the relationship between wave path and event frequency content.

Evaluating Monitoring Strategies to Detect Precipitation-Induced Microbial Contamination Events in Karstic Springs Used for Drinking Water

PubMed Central

Besmer, Michael D.; Hammes, Frederik; Sigrist, Jürg A.; Ort, Christoph

2017-01-01

Monitoring of microbial drinking water quality is a key component for ensuring safety and understanding risk, but conventional monitoring strategies are typically based on low sampling frequencies (e.g., quarterly or monthly). This is of concern because many drinking water sources, such as karstic springs are often subject to changes in bacterial concentrations on much shorter time scales (e.g., hours to days), for example after precipitation events. Microbial contamination events are crucial from a risk assessment perspective and should therefore be targeted by monitoring strategies to establish both the frequency of their occurrence and the magnitude of bacterial peak concentrations. In this study we used monitoring data from two specific karstic springs. We assessed the performance of conventional monitoring based on historical records and tested a number of alternative strategies based on a high-resolution data set of bacterial concentrations in spring water collected with online flow cytometry (FCM). We quantified the effect of increasing sampling frequency and found that for the specific case studied, at least bi-weekly sampling would be needed to detect precipitation events with a probability of >90%. We then proposed an optimized monitoring strategy with three targeted samples per event, triggered by precipitation measurements. This approach is more effective and efficient than simply increasing overall sampling frequency. It would enable the water utility to (1) analyze any relevant event and (2) limit median underestimation of peak concentrations to approximately 10%. We conclude with a generalized perspective on sampling optimization and argue that the assessment of short-term dynamics causing microbial peak loads initially requires increased sampling/analysis efforts, but can be optimized subsequently to account for limited resources. This offers water utilities and public health authorities systematic ways to evaluate and optimize their current monitoring strategies. PMID:29213255

Evaluating Monitoring Strategies to Detect Precipitation-Induced Microbial Contamination Events in Karstic Springs Used for Drinking Water.

PubMed

Besmer, Michael D; Hammes, Frederik; Sigrist, Jürg A; Ort, Christoph

2017-01-01

Monitoring of microbial drinking water quality is a key component for ensuring safety and understanding risk, but conventional monitoring strategies are typically based on low sampling frequencies (e.g., quarterly or monthly). This is of concern because many drinking water sources, such as karstic springs are often subject to changes in bacterial concentrations on much shorter time scales (e.g., hours to days), for example after precipitation events. Microbial contamination events are crucial from a risk assessment perspective and should therefore be targeted by monitoring strategies to establish both the frequency of their occurrence and the magnitude of bacterial peak concentrations. In this study we used monitoring data from two specific karstic springs. We assessed the performance of conventional monitoring based on historical records and tested a number of alternative strategies based on a high-resolution data set of bacterial concentrations in spring water collected with online flow cytometry (FCM). We quantified the effect of increasing sampling frequency and found that for the specific case studied, at least bi-weekly sampling would be needed to detect precipitation events with a probability of >90%. We then proposed an optimized monitoring strategy with three targeted samples per event, triggered by precipitation measurements. This approach is more effective and efficient than simply increasing overall sampling frequency. It would enable the water utility to (1) analyze any relevant event and (2) limit median underestimation of peak concentrations to approximately 10%. We conclude with a generalized perspective on sampling optimization and argue that the assessment of short-term dynamics causing microbial peak loads initially requires increased sampling/analysis efforts, but can be optimized subsequently to account for limited resources. This offers water utilities and public health authorities systematic ways to evaluate and optimize their current monitoring strategies.

Detector Sampling of Optical/IR Spectra: How Many Pixels per FWHM?

NASA Astrophysics Data System (ADS)

Robertson, J. Gordon

2017-08-01

Most optical and IR spectra are now acquired using detectors with finite-width pixels in a square array. Each pixel records the received intensity integrated over its own area, and pixels are separated by the array pitch. This paper examines the effects of such pixellation, using computed simulations to illustrate the effects which most concern the astronomer end-user. It is shown that coarse sampling increases the random noise errors in wavelength by typically 10-20 % at 2 pixels per Full Width at Half Maximum, but with wide variation depending on the functional form of the instrumental Line Spread Function (i.e. the instrumental response to a monochromatic input) and on the pixel phase. If line widths are determined, they are even more strongly affected at low sampling frequencies. However, the noise in fitted peak amplitudes is minimally affected by pixellation, with increases less than about 5%. Pixellation has a substantial but complex effect on the ability to see a relative minimum between two closely spaced peaks (or relative maximum between two absorption lines). The consistent scale of resolving power presented by Robertson to overcome the inadequacy of the Full Width at Half Maximum as a resolution measure is here extended to cover pixellated spectra. The systematic bias errors in wavelength introduced by pixellation, independent of signal/noise ratio, are examined. While they may be negligible for smooth well-sampled symmetric Line Spread Functions, they are very sensitive to asymmetry and high spatial frequency sub-structure. The Modulation Transfer Function for sampled data is shown to give a useful indication of the extent of improperly sampled signal in an Line Spread Function. The common maxim that 2 pixels per Full Width at Half Maximum is the Nyquist limit is incorrect and most Line Spread Functions will exhibit some aliasing at this sample frequency. While 2 pixels per Full Width at Half Maximum is nevertheless often an acceptable minimum for moderate signal/noise work, it is preferable to carry out simulations for any actual or proposed Line Spread Function to find the effects of various sampling frequencies. Where spectrograph end-users have a choice of sampling frequencies, through on-chip binning and/or spectrograph configurations, it is desirable that the instrument user manual should include an examination of the effects of the various choices.

78 FR 14457 - Guidelines Establishing Test Procedures for the Analysis of Pollutants Under the Clean Water Act...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-06

... Establishing Test Procedures for the Analysis of Pollutants Under the Clean Water Act; Analysis and Sampling... for use as an alternative oil and grease method. Some comments were specific to the sampling...-side comparison using the specific procedures (e.g. sampling frequency, number of samples, QA/QC, and...

Radar Doppler Processing with Nonuniform Sampling.

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

Doerry, Armin W.

2017-07-01

Conventional signal processing to estimate radar Doppler frequency often assumes uniform pulse/sample spacing. This is for the convenience of t he processing. More recent performance enhancements in processor capability allow optimally processing nonuniform pulse/sample spacing, thereby overcoming some of the baggage that attends uniform sampling, such as Doppler ambiguity and SNR losses due to sidelobe control measures.

Sampling. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

ERIC Educational Resources Information Center

Carnegie, John W.

A brief overview of the basic concepts and philosophies for sampling water and waste water systems is presented in this module. The module is not intended to specify sampling procedures, frequencies, or locations for specific treatment facilities but rather to outline those general procedures which should be followed when sampling under most…

Acoustic Translation of an Acoustically Levitated Sample

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Allen, J. L.

1986-01-01

Acoustic-levitation apparatus uses only one acoustic mode to move sample from one region of chamber to another. Sample heated and cooled quickly by translation between hot and cold regions of levitation chamber. Levitated sample is raised into furnace region by raising plunger. Frequency of sound produced by transducers adjusted by feedback system to maintain (102) resonant mode, which levitates sample midway between transducers and plunger regardless of plunger position.

A remark on the theory of measuring thermal diffusivity by the modified Angstrom's method. [in lunar samples

NASA Technical Reports Server (NTRS)

Horai, K.-I.

1981-01-01

A theory of the measurement of the thermal diffusivity of a sample by the modified Angstrom method is developed for the case in which radiative heat loss from the end surface of the sample is not negligible, and applied to measurements performed on lunar samples. Formulas allowing sample thermal diffusivity to be determined from the amplitude decay and phase lag of a temperature wave traveling through the sample are derived for a flat disk sample for which only heat loss from the end surface is important, and a sample of finite diameter and length for which heat loss through the end and side surfaces must be considered. It is noted that in the case of a flat disk, measurements at a single angular frequency of the temperature wave are sufficient, while the sample of finite diameter and length requires measurements at two discrete angular frequencies. Comparison of the values of the thermal diffusivities of two lunar samples of dimensions approximately 1 x 1 x 2 cm derived by the present methods and by the Angstrom theory for a finite bar reveals them to differ by not more than 5%, and indicates that more refined data are required as the measurement theory becomes more complicated.

Development of Dielectric Material with Ceramic Matrix Composite (CMC) Produced from Kaolinite and CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO)

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

Yin, Wong Swee; Hassan, Jumiah; Hashim, Mansor

Ceramic matrix composites (CMC) combine reinforcing ceramic phases, CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) with a ceramic matrix, kaolinite to create materials with new and superior properties. 10% and 20% CCTO were prepared by using a conventional solid state reaction method. CMC samples were pre-sintered at 800 deg. C and sintered at 1000 deg. C. The dielectric properties of samples were measured using HP 4192A LF Impedance Analyzer. Microstructures of the samples were observed using an optical microscope. XRD was used to determine the crystalline structure of the samples. The AFM showed the morphology of the samples. The results showed thatmore » the dielectric constant and dielectric loss factor of both samples are frequency dependent. At 10 Hz, the dielectric constant is 10{sup 11} for both samples. The CMC samples were independent with temperature with low dielectric constant in the frequency range of 10{sup 4}-10{sup 6} Hz. Since the CMC samples consist of different amount of kaolinite, so each sample exhibit different defect mechanism. Different reaction may occur for different composition of material. The effects of processing conditions on the microstructure and electrical properties of CMC are also discussed.« less

The window of visibility: A psychological theory of fidelity in time-sampled visual motion displays

NASA Technical Reports Server (NTRS)

Watson, A. B.; Ahumada, A. J., Jr.; Farrell, J. E.

1983-01-01

Many visual displays, such as movies and television, rely upon sampling in the time domain. The spatiotemporal frequency spectra for some simple moving images are derived and illustrations of how these spectra are altered by sampling in the time domain are provided. A simple model of the human perceiver which predicts the critical sample rate required to render sampled and continuous moving images indistinguishable is constructed. The rate is shown to depend upon the spatial and temporal acuity of the observer, and upon the velocity and spatial frequency content of the image. Several predictions of this model are tested and confirmed. The model is offered as an explanation of many of the phenomena known as apparent motion. Finally, the implications of the model for computer-generated imagery are discussed.

Measurement system

NASA Technical Reports Server (NTRS)

Turner, J. W. (Inventor)

1973-01-01

A measurement system is described for providing an indication of a varying physical quantity represented by or converted to a variable frequency signal. Timing pulses are obtained marking the duration of a fixed number, or set, of cycles of the sampled signal and these timing pulses are employed to control the period of counting of cycles of a higher fixed and known frequency source. The counts of cycles obtained from the fixed frequency source provide a precise measurement of the average frequency of each set of cycles sampled, and thus successive discrete values of the quantity being measured. The frequency of the known frequency source is made such that each measurement is presented as a direct digital representation of the quantity measured.

Assessment of the Minimum Sampling Frequency to Avoid Measurement Redundancy in Microclimate Field Surveys in Museum Buildings.

PubMed

García-Diego, Fernando-Juan; Verticchio, Elena; Beltrán, Pedro; Siani, Anna Maria

2016-08-15

Monitoring temperature and relative humidity of the environment to which artefacts are exposed is fundamental in preventive conservation studies. The common approach in setting measuring instruments is the choice of a high sampling rate to detect short fluctuations and increase the accuracy of statistical analysis. However, in recent cultural heritage standards the evaluation of variability is based on moving average and short fluctuations and therefore massive acquisition of data in slowly-changing indoor environments could end up being redundant. In this research, the sampling frequency to set a datalogger in a museum room and inside a microclimate frame is investigated by comparing the outcomes obtained from datasheets associated with different sampling conditions. Thermo-hygrometric data collected in the Sorolla room of the Pio V Museum of Valencia (Spain) were used and the widely consulted recommendations issued in UNI 10829:1999 and EN 15757:2010 standards and in the American Society of Heating, Air-Conditioning and Refrigerating Engineers (ASHRAE) guidelines were applied. Hourly sampling proved effective in obtaining highly reliable results. Furthermore, it was found that in some instances daily means of data sampled every hour can lead to the same conclusions as those of high frequency. This allows us to improve data logging design and manageability of the resulting datasheets.

Accident prediction model for public highway-rail grade crossings.

PubMed

Lu, Pan; Tolliver, Denver

2016-05-01

Considerable research has focused on roadway accident frequency analysis, but relatively little research has examined safety evaluation at highway-rail grade crossings. Highway-rail grade crossings are critical spatial locations of utmost importance for transportation safety because traffic crashes at highway-rail grade crossings are often catastrophic with serious consequences. The Poisson regression model has been employed to analyze vehicle accident frequency as a good starting point for many years. The most commonly applied variations of Poisson including negative binomial, and zero-inflated Poisson. These models are used to deal with common crash data issues such as over-dispersion (sample variance is larger than the sample mean) and preponderance of zeros (low sample mean and small sample size). On rare occasions traffic crash data have been shown to be under-dispersed (sample variance is smaller than the sample mean) and traditional distributions such as Poisson or negative binomial cannot handle under-dispersion well. The objective of this study is to investigate and compare various alternate highway-rail grade crossing accident frequency models that can handle the under-dispersion issue. The contributions of the paper are two-fold: (1) application of probability models to deal with under-dispersion issues and (2) obtain insights regarding to vehicle crashes at public highway-rail grade crossings. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of the Minimum Sampling Frequency to Avoid Measurement Redundancy in Microclimate Field Surveys in Museum Buildings

PubMed Central

García-Diego, Fernando-Juan; Verticchio, Elena; Beltrán, Pedro; Siani, Anna Maria

2016-01-01

Monitoring temperature and relative humidity of the environment to which artefacts are exposed is fundamental in preventive conservation studies. The common approach in setting measuring instruments is the choice of a high sampling rate to detect short fluctuations and increase the accuracy of statistical analysis. However, in recent cultural heritage standards the evaluation of variability is based on moving average and short fluctuations and therefore massive acquisition of data in slowly-changing indoor environments could end up being redundant. In this research, the sampling frequency to set a datalogger in a museum room and inside a microclimate frame is investigated by comparing the outcomes obtained from datasheets associated with different sampling conditions. Thermo-hygrometric data collected in the Sorolla room of the Pio V Museum of Valencia (Spain) were used and the widely consulted recommendations issued in UNI 10829:1999 and EN 15757:2010 standards and in the American Society of Heating, Air-Conditioning and Refrigerating Engineers (ASHRAE) guidelines were applied. Hourly sampling proved effective in obtaining highly reliable results. Furthermore, it was found that in some instances daily means of data sampled every hour can lead to the same conclusions as those of high frequency. This allows us to improve data logging design and manageability of the resulting datasheets. PMID:27537886

Efficient inference of population size histories and locus-specific mutation rates from large-sample genomic variation data.

PubMed

Bhaskar, Anand; Wang, Y X Rachel; Song, Yun S

2015-02-01

With the recent increase in study sample sizes in human genetics, there has been growing interest in inferring historical population demography from genomic variation data. Here, we present an efficient inference method that can scale up to very large samples, with tens or hundreds of thousands of individuals. Specifically, by utilizing analytic results on the expected frequency spectrum under the coalescent and by leveraging the technique of automatic differentiation, which allows us to compute gradients exactly, we develop a very efficient algorithm to infer piecewise-exponential models of the historical effective population size from the distribution of sample allele frequencies. Our method is orders of magnitude faster than previous demographic inference methods based on the frequency spectrum. In addition to inferring demography, our method can also accurately estimate locus-specific mutation rates. We perform extensive validation of our method on simulated data and show that it can accurately infer multiple recent epochs of rapid exponential growth, a signal that is difficult to pick up with small sample sizes. Lastly, we use our method to analyze data from recent sequencing studies, including a large-sample exome-sequencing data set of tens of thousands of individuals assayed at a few hundred genic regions. © 2015 Bhaskar et al.; Published by Cold Spring Harbor Laboratory Press.

Classification of heavy metal ions present in multi-frequency multi-electrode potable water data using evolutionary algorithm

NASA Astrophysics Data System (ADS)

Karkra, Rashmi; Kumar, Prashant; Bansod, Baban K. S.; Bagchi, Sudeshna; Sharma, Pooja; Krishna, C. Rama

2017-11-01

Access to potable water for the common people is one of the most challenging tasks in the present era. Contamination of drinking water has become a serious problem due to various anthropogenic and geogenic events. The paper demonstrates the application of evolutionary algorithms, viz., particle swan optimization and genetic algorithm to 24 water samples containing eight different heavy metal ions (Cd, Cu, Co, Pb, Zn, Ar, Cr and Ni) for the optimal estimation of electrode and frequency to classify the heavy metal ions. The work has been carried out on multi-variate data, viz., single electrode multi-frequency, single frequency multi-electrode and multi-frequency multi-electrode water samples. The electrodes used are platinum, gold, silver nanoparticles and glassy carbon electrodes. Various hazardous metal ions present in the water samples have been optimally classified and validated by the application of Davis Bouldin index. Such studies are useful in the segregation of hazardous heavy metal ions found in water resources, thereby quantifying the degree of water quality.

Evaluation of a lower-powered analyzer and sampling system for eddy-covariance measurements of nitrous oxide fluxes

NASA Astrophysics Data System (ADS)

Brown, Shannon E.; Sargent, Steve; Wagner-Riddle, Claudia

2018-03-01

Nitrous oxide (N2O) fluxes measured using the eddy-covariance method capture the spatial and temporal heterogeneity of N2O emissions. Most closed-path trace-gas analyzers for eddy-covariance measurements have large-volume, multi-pass absorption cells that necessitate high flow rates for ample frequency response, thus requiring high-power sample pumps. Other sampling system components, including rain caps, filters, dryers, and tubing, can also degrade system frequency response. This field trial tested the performance of a closed-path eddy-covariance system for N2O flux measurements with improvements to use less power while maintaining the frequency response. The new system consists of a thermoelectrically cooled tunable diode laser absorption spectrometer configured to measure both N2O and carbon dioxide (CO2). The system features a relatively small, single-pass sample cell (200 mL) that provides good frequency response with a lower-powered pump ( ˜ 250 W). A new filterless intake removes particulates from the sample air stream with no additional mixing volume that could degrade frequency response. A single-tube dryer removes water vapour from the sample to avoid the need for density or spectroscopic corrections, while maintaining frequency response. This eddy-covariance system was collocated with a previous tunable diode laser absorption spectrometer model to compare N2O and CO2 flux measurements for two full growing seasons (May 2015 to October 2016) in a fertilized cornfield in Southern Ontario, Canada. Both spectrometers were placed outdoors at the base of the sampling tower, demonstrating ruggedness for a range of environmental conditions (minimum to maximum daily temperature range: -26.1 to 31.6 °C). The new system rarely required maintenance. An in situ frequency-response test demonstrated that the cutoff frequency of the new system was better than the old system (3.5 Hz compared to 2.30 Hz) and similar to that of a closed-path CO2 eddy-covariance system (4.05 Hz), using shorter tubing and no dryer, that was also collocated at the site. Values of the N2O fluxes were similar between the two spectrometer systems (slope = 1.01, r2 = 0.96); CO2 fluxes as measured by the short-tubed eddy-covariance system and the two spectrometer systems correlated well (slope = 1.03, r2 = 0.998). The new lower-powered tunable diode laser absorption spectrometer configuration with the filterless intake and single-tube dryer showed promise for deployment in remote areas.

FREQUENCY OF ANEUPLOID SPERMATOZOA STUDIED BY MULTICOLOR FISH IN SERIAL SEMEN SAMPLES

EPA Science Inventory

Frequency of aneuploid spermatozoa studied by multicolor FISH in serial semen samples

M. Vozdova1, S. D. Perreault2, O. Rezacova1, D. Zudova1 , Z. Zudova3, S. G. Selevan4, J. Rubes1,5
1Veterinary Research Institute, Brno, Czech Republic; 2U.S. Environmental Protection A...

Improved argument-FFT frequency offset estimation for QPSK coherent optical Systems

NASA Astrophysics Data System (ADS)

Han, Jilong; Li, Wei; Yuan, Zhilin; Li, Haitao; Huang, Liyan; Hu, Qianggao

2016-02-01

A frequency offset estimation (FOE) algorithm based on fast Fourier transform (FFT) of the signal's argument is investigated, which does not require removing the modulated data phase. In this paper, we analyze the flaw of the argument-FFT algorithm and propose a combined FOE algorithm, in which the absolute of frequency offset (FO) is accurately calculated by argument-FFT algorithm with a relatively large number of samples and the sign of FO is determined by FFT-based interpolation discrete Fourier transformation (DFT) algorithm with a relatively small number of samples. Compared with the previous algorithms based on argument-FFT, the proposed one has low complexity and can still effectively work with a relatively less number of samples.

Frequency of Propionibacterium acnes Infection in Prostate Glands with Negative Biopsy Results Is an Independent Risk Factor for Prostate Cancer in Patients with Increased Serum PSA Titers

PubMed Central

Ito, Takashi; Uchida, Keisuke; Sekine, Masaki; Nakajima, Yutaka; Furukawa, Asuka; Suzuki, Yoshimi; Kumagai, Jiro; Akashi, Takumi

2017-01-01

Background Propionibacterium acnes has recently been implicated as a cause of chronic prostatitis and this commensal bacterium may be linked to prostate carcinogenesis. The occurrence of intracellular P. acnes infection in prostate glands and the higher frequency of P. acnes-positive glands in radical prostatectomy specimens from patients with prostate cancer (PCa) than in those from patients without PCa led us to examine whether the P. acnes-positive gland frequency can be used to assess the risk for PCa in patients whose first prostate biopsy, performed due to an increased prostate-specific antigen (PSA) titer, was negative. Methods We retrospectively collected the first and last prostate biopsy samples from 44 patients that were diagnosed PCa within 4 years after the first negative biopsy and from 36 control patients with no PCa found in repeated biopsy for at least 3 years after the first biopsy. We evaluated P. acnes-positive gland frequency and P. acnes-positive macrophage number using enzyme-immunohistochemistry with a P. acnes-specific monoclonal antibody (PAL antibody). Results The frequency of P. acnes-positive glands was higher in PCa samples than in control samples in both first biopsy samples and in combined first and last biopsy samples (P < 0.001). A frequency greater than the threshold (18.5 and 17.7, respectively) obtained by each receiver operating characteristic curve was an independent risk factor for PCa (P = 0.003 and 0.001, respectively) with odds ratios (14.8 and 13.9, respectively) higher than those of serum PSA titers of patients just before each biopsy (4.6 and 2.3, respectively). The number of P. acnes-positive macrophages did not differ significantly between PCa and control samples. Conclusions These results suggested that the frequency of P. acnes-positive glands in the first negative prostate biopsy performed due to increased PSA titers can be supportive information for urologists in planning repeated biopsy or follow-up strategies. PMID:28081259

40 CFR 270.62 - Hazardous waste incinerator permits.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Stack gas monitoring and pollution control equipment. (H) Nozzle and burner design. (I) Construction.... (iii) A detailed description of sampling and monitoring procedures, including sampling and monitoring locations in the system, the equipment to be used, sampling and monitoring frequency, and planned analytical...

Differential sampling for fast frequency acquisition via adaptive extended least squares algorithm

NASA Technical Reports Server (NTRS)

Kumar, Rajendra

1987-01-01

This paper presents a differential signal model along with appropriate sampling techinques for least squares estimation of the frequency and frequency derivatives and possibly the phase and amplitude of a sinusoid received in the presence of noise. The proposed algorithm is recursive in mesurements and thus the computational requirement increases only linearly with the number of measurements. The dimension of the state vector in the proposed algorithm does not depend upon the number of measurements and is quite small, typically around four. This is an advantage when compared to previous algorithms wherein the dimension of the state vector increases monotonically with the product of the frequency uncertainty and the observation period. Such a computational simplification may possibly result in some loss of optimality. However, by applying the sampling techniques of the paper such a possible loss in optimality can made small.

Evaluation of the statistical evidence for Characteristic Earthquakes in the frequency-magnitude distributions of Sumatra and other subduction zone regions

NASA Astrophysics Data System (ADS)

Naylor, M.; Main, I. G.; Greenhough, J.; Bell, A. F.; McCloskey, J.

2009-04-01

The Sumatran Boxing Day earthquake and subsequent large events provide an opportunity to re-evaluate the statistical evidence for characteristic earthquake events in frequency-magnitude distributions. Our aims are to (i) improve intuition regarding the properties of samples drawn from power laws, (ii) illustrate using random samples how appropriate Poisson confidence intervals can both aid the eye and provide an appropriate statistical evaluation of data drawn from power-law distributions, and (iii) apply these confidence intervals to test for evidence of characteristic earthquakes in subduction-zone frequency-magnitude distributions. We find no need for a characteristic model to describe frequency magnitude distributions in any of the investigated subduction zones, including Sumatra, due to an emergent skew in residuals of power law count data at high magnitudes combined with a sample bias for examining large earthquakes as candidate characteristic events.

Modulated microwave microscopy and probes used therewith

DOEpatents

Lai, Keji; Kelly, Michael; Shen, Zhi-Xun

2012-09-11

A microwave microscope including a probe tip electrode vertically positionable over a sample and projecting downwardly from the end of a cantilever. A transmission line connecting the tip electrode to the electronic control system extends along the cantilever and is separated from a ground plane at the bottom of the cantilever by a dielectric layer. The probe tip may be vertically tapped near or at the sample surface at a low frequency and the microwave signal reflected from the tip/sample interaction is demodulated at the low frequency. Alternatively, a low-frequency electrical signal is also a non-linear electrical element associated with the probe tip to non-linearly interact with the applied microwave signal and the reflected non-linear microwave signal is detected at the low frequency. The non-linear element may be semiconductor junction formed near the apex of the probe tip or be an FET formed at the base of a semiconducting tip.

A novel multi-scale adaptive sampling-based approach for energy saving in leak detection for WSN-based water pipelines

NASA Astrophysics Data System (ADS)

Saqib, Najam us; Faizan Mysorewala, Muhammad; Cheded, Lahouari

2017-12-01

In this paper, we propose a novel monitoring strategy for a wireless sensor networks (WSNs)-based water pipeline network. Our strategy uses a multi-pronged approach to reduce energy consumption based on the use of two types of vibration sensors and pressure sensors, all having different energy levels, and a hierarchical adaptive sampling mechanism to determine the sampling frequency. The sampling rate of the sensors is adjusted according to the bandwidth of the vibration signal being monitored by using a wavelet-based adaptive thresholding scheme that calculates the new sampling frequency for the following cycle. In this multimodal sensing scheme, the duty-cycling approach is used for all sensors to reduce the sampling instances, such that the high-energy, high-precision (HE-HP) vibration sensors have low duty cycles, and the low-energy, low-precision (LE-LP) vibration sensors have high duty cycles. The low duty-cycling (HE-HP) vibration sensor adjusts the sampling frequency of the high duty-cycling (LE-LP) vibration sensor. The simulated test bed considered here consists of a water pipeline network which uses pressure and vibration sensors, with the latter having different energy consumptions and precision levels, at various locations in the network. This is all the more useful for energy conservation for extended monitoring. It is shown that by using the novel features of our proposed scheme, a significant reduction in energy consumption is achieved and the leak is effectively detected by the sensor node that is closest to it. Finally, both the total energy consumed by monitoring as well as the time to detect the leak by a WSN node are computed, and show the superiority of our proposed hierarchical adaptive sampling algorithm over a non-adaptive sampling approach.

The influence of sampling interval on the accuracy of trail impact assessment

USGS Publications Warehouse

Leung, Y.-F.; Marion, J.L.

1999-01-01

Trail impact assessment and monitoring (IA&M) programs have been growing in importance and application in recreation resource management at protected areas. Census-based and sampling-based approaches have been developed in such programs, with systematic point sampling being the most common survey design. This paper examines the influence of sampling interval on the accuracy of estimates for selected trail impact problems. A complete census of four impact types on 70 trails in Great Smoky Mountains National Park was utilized as the base data set for the analyses. The census data were resampled at increasing intervals to create a series of simulated point data sets. Estimates of frequency of occurrence and lineal extent for the four impact types were compared with the census data set. The responses of accuracy loss on lineal extent estimates to increasing sampling intervals varied across different impact types, while the responses on frequency of occurrence estimates were consistent, approximating an inverse asymptotic curve. These findings suggest that systematic point sampling may be an appropriate method for estimating the lineal extent but not the frequency of trail impacts. Sample intervals of less than 100 m appear to yield an excellent level of accuracy for the four impact types evaluated. Multiple regression analysis results suggest that appropriate sampling intervals are more likely to be determined by the type of impact in question rather than the length of trail. The census-based trail survey and the resampling-simulation method developed in this study can be a valuable first step in establishing long-term trail IA&M programs, in which an optimal sampling interval range with acceptable accuracy is determined before investing efforts in data collection.

The differential path phase comparison method for determining pressure derivatives of elastic constants of solids

NASA Astrophysics Data System (ADS)

Peselnick, L.

1982-08-01

An ultrasonic method is presented which combines features of the differential path and the phase comparison methods. The proposed differential path phase comparison method, referred to as the `hybrid' method for brevity, eliminates errors resulting from phase changes in the bond between the sample and buffer rod. Define r(P) [and R(P)] as the square of the normalized frequency for cancellation of sample waves for shear [and for compressional] waves. Define N as the number of wavelengths in twice the sample length. The pressure derivatives r'(P) and R' (P) for samples of Alcoa 2024-T4 aluminum were obtained by using the phase comparison and the hybrid methods. The values of the pressure derivatives obtained by using the phase comparison method show variations by as much as 40% for small values of N (N < 50). The pressure derivatives as determined from the hybrid method are reproducible to within ±2% independent of N. The values of the pressure derivatives determined by the phase comparison method for large N are the same as those determined by the hybrid method. Advantages of the hybrid method are (1) no pressure dependent phase shift at the buffer-sample interface, (2) elimination of deviatoric stress in the sample portion of the sample assembly with application of hydrostatic pressure, and (3) operation at lower ultrasonic frequencies (for comparable sample lengths), which eliminates detrimental high frequency ultrasonic problems. A reduction of the uncertainties of the pressure derivatives of single crystals and of low porosity polycrystals permits extrapolation of such experimental data to deeper mantle depths.

A scanning tunneling microscope capable of imaging specified micron-scale small samples.

PubMed

Tao, Wei; Cao, Yufei; Wang, Huafeng; Wang, Kaiyou; Lu, Qingyou

2012-12-01

We present a home-built scanning tunneling microscope (STM) which allows us to precisely position the tip on any specified small sample or sample feature of micron scale. The core structure is a stand-alone soft junction mechanical loop (SJML), in which a small piezoelectric tube scanner is mounted on a sliding piece and a "U"-like soft spring strip has its one end fixed to the sliding piece and its opposite end holding the tip pointing to the sample on the scanner. Here, the tip can be precisely aligned to a specified small sample of micron scale by adjusting the position of the spring-clamped sample on the scanner in the field of view of an optical microscope. The aligned SJML can be transferred to a piezoelectric inertial motor for coarse approach, during which the U-spring is pushed towards the sample, causing the tip to approach the pre-aligned small sample. We have successfully approached a hand cut tip that was made from 0.1 mm thin Pt∕Ir wire to an isolated individual 32.5 × 32.5 μm(2) graphite flake. Good atomic resolution images and high quality tunneling current spectra for that specified tiny flake are obtained in ambient conditions with high repeatability within one month showing high and long term stability of the new STM structure. In addition, frequency spectra of the tunneling current signals do not show outstanding tip mount related resonant frequency (low frequency), which further confirms the stability of the STM structure.

Radio-frequency characteristic variation of interdigital capacitor having multilayer graphene of various widths

NASA Astrophysics Data System (ADS)

Lee, Hee-Jo; Hong, Young-Pyo

2018-03-01

In this paper, a radio-frequency circuit model of an interdigital capacitor (IDC) with a multilayer graphene (MLG) width variation is proposed. The circuit model with three sample configurations, i.e., a bare IDC, IDC-MLG with a width of 5 μm, and IDC-MLG with a width of 20 μm, is constructed via a fitted method based on the measured samples. The simulated results of the circuit model are validated through the RF characteristics, e.g., the capacitance and the self-resonance frequency, of the measured samples. From the circuit model, all samples show not only a similar capacitance behavior but also an identical self-resonance frequency of 10 GHz. Moreover, the R, L, and C values of MLG with a 5 μm width (MLG with a 20 μm width) alone are approximately 0.8 kΩ (0.5 kΩ), 0.5 nH (0.9 nH), and 0.3 pF (0.1 pF), respectively. As a result, we find that the simulated results are in good agreement with RF characteristics of the measured samples. In the future, we expect that the proposed circuit model of an IDC with MLG will offer assistance with performance predictions of diverse IDC-based 2D material applications, such as biosensors and gas sensors, as well as supercapacitors.

Shear wave anisotropy from aligned inclusions: ultrasonic frequency dependence of velocity and attenuation

NASA Astrophysics Data System (ADS)

de Figueiredo, J. J. S.; Schleicher, J.; Stewart, R. R.; Dayur, N.; Omoboya, B.; Wiley, R.; William, A.

2013-04-01

To understand their influence on elastic wave propagation, anisotropic cracked media have been widely investigated in many theoretical and experimental studies. In this work, we report on laboratory ultrasound measurements carried out to investigate the effect of source frequency on the elastic parameters (wave velocities and the Thomsen parameter γ) and shear wave attenuation) of fractured anisotropic media. Under controlled conditions, we prepared anisotropic model samples containing penny-shaped rubber inclusions in a solid epoxy resin matrix with crack densities ranging from 0 to 6.2 per cent. Two of the three cracked samples have 10 layers and one has 17 layers. The number of uniform rubber inclusions per layer ranges from 0 to 100. S-wave splitting measurements have shown that scattering effects are more prominent in samples where the seismic wavelength to crack aperture ratio ranges from 1.6 to 1.64 than in others where the ratio varied from 2.72 to 2.85. The sample with the largest cracks showed a magnitude of scattering attenuation three times higher compared with another sample that had small inclusions. Our S-wave ultrasound results demonstrate that elastic scattering, scattering and anelastic attenuation, velocity dispersion and crack size interfere directly in shear wave splitting in a source-frequency dependent manner, resulting in an increase of scattering attenuation and a reduction of shear wave anisotropy with increasing frequency.

On-field measurement trial of 4×128 Gbps PDM-QPSK signals by linear optical sampling

NASA Astrophysics Data System (ADS)

Bin Liu; Wu, Zhichao; Fu, Songnian; Feng, Yonghua; Liu, Deming

2017-02-01

Linear optical sampling is a promising characterization technique for advanced modulation formats, together with digital signal processing (DSP) and software-synchronized algorithm. We theoretically investigate the acquisition of optical sampling, when the high-speed signal under test is either periodic or random. Especially, when the profile of optical sampling pulse is asymmetrical, the repetition frequency of sampling pulse needs careful adjustment in order to obtain correct waveform. Then, we demonstrate on-field measurement trial of commercial four-channel 128 Gbps polarization division multiplexing quadrature phase shift keying (PDM-QPSK) signals with truly random characteristics by self-developed equipment. A passively mode-locked fiber laser (PMFL) with a repetition frequency of 95.984 MHz is used as optical sampling source, meanwhile four balanced photo detectors (BPDs) with 400 MHz bandwidth and four-channel analog-to-digital convertor (ADC) with 1.25 GS/s sampling rate are used for data acquisition. The performance comparison with conventional optical modulation analyzer (OMA) verifies that the self-developed equipment has the advantages of low cost, easy implementation, and fast response.

True non-contact atomic force microscopy imaging of heterogeneous biological samples in liquids: topography and material contrast.

PubMed

Almonte, Lisa; Colchero, Jaime

2017-02-23

The present work analyses how the tip-sample interaction signals critically determine the operation of an Atomic Force Microscope (AFM) set-up immersed in liquid. On heterogeneous samples, the conservative tip-sample interaction may vary significantly from point to point - in particular from attractive to repulsive - rendering correct feedback very challenging. Lipid membranes prepared on a mica substrate are analyzed as reference samples which are locally heterogeneous (material contrast). The AFM set-up is operated dynamically at low oscillation amplitude and all available experimental data signals - the normal force, as well as the amplitude and frequency - are recorded simultaneously. From the analysis of how the dissipation (oscillation amplitude) and the conservative interaction (normal force and resonance frequency) vary with the tip-sample distance we conclude that dissipation is the only appropriate feedback source for stable and correct topographic imaging. The normal force and phase then carry information about the sample composition ("chemical contrast"). Dynamic AFM allows imaging in a non-contact regime where essentially no forces are applied, rendering dynamic AFM a truly non-invasive technique.

Magnitude error bounds for sampled-data frequency response obtained from the truncation of an infinite series, and compensator improvement program

NASA Technical Reports Server (NTRS)

Mitchell, J. R.

1972-01-01

The frequency response method of analyzing control system performance is discussed, and the difficulty of obtaining the sampled frequency response of the continuous system is considered. An upper bound magnitude error equation is obtained which yields reasonable estimates of the actual error. Finalization of the compensator improvement program is also reported, and the program was used to design compensators for Saturn 5/S1-C dry workshop and Saturn 5/S1-C Skylab.

ACS sampling system: design, implementation, and performance evaluation

NASA Astrophysics Data System (ADS)

Di Marcantonio, Paolo; Cirami, Roberto; Chiozzi, Gianluca

2004-09-01

By means of ACS (ALMA Common Software) framework we designed and implemented a sampling system which allows sampling of every Characteristic Component Property with a specific, user-defined, sustained frequency limited only by the hardware. Collected data are sent to various clients (one or more Java plotting widgets, a dedicated GUI or a COTS application) using the ACS/CORBA Notification Channel. The data transport is optimized: samples are cached locally and sent in packets with a lower and user-defined frequency to keep network load under control. Simultaneous sampling of the Properties of different Components is also possible. Together with the design and implementation issues we present the performance of the sampling system evaluated on two different platforms: on a VME based system using VxWorks RTOS (currently adopted by ALMA) and on a PC/104+ embedded platform using Red Hat 9 Linux operating system. The PC/104+ solution offers, as an alternative, a low cost PC compatible hardware environment with free and open operating system.

Discriminator Stabilized Superconductor/Ferroelectric Thin Film Local Oscillator

NASA Technical Reports Server (NTRS)

Romanofsky, Robert R. (Inventor); Miranda, Felix A. (Inventor)

2000-01-01

A tunable local oscillator with a tunable circuit that includes a resonator and a transistor as an active element for oscillation. Tuning of the circuit is achieved with an externally applied dc bias across coupled lines on the resonator. Preferably the resonator is a high temperature superconductor microstrip ring resonator with integral coupled lines formed over a thin film ferroelectric material. A directional coupler samples the output of the oscillator which is fed into a diplexer for determining whether the oscillator is performing at a desired frequency. The high-pass and lowpass outputs of the diplexer are connected to diodes respectively for inputting the sampled signals into a differential operational amplifier. The amplifier compares the sampled signals and emits an output signal if there is a difference between the resonant and crossover frequencies. Based on the sampled signal, a bias supplied to the ring resonator is either increased or decreased for raising or lowering the resonant frequency by decreasing or increasing, respectively, the dielectric constant of the ferroelectric.

ECCM Scheme against Interrupted Sampling Repeater Jammer Based on Parameter-Adjusted Waveform Design

PubMed Central

Wei, Zhenhua; Peng, Bo; Shen, Rui

2018-01-01

Interrupted sampling repeater jamming (ISRJ) is an effective way of deceiving coherent radar sensors, especially for linear frequency modulated (LFM) radar. In this paper, for a simplified scenario with a single jammer, we propose a dynamic electronic counter-counter measure (ECCM) scheme based on jammer parameter estimation and transmitted signal design. Firstly, the LFM waveform is transmitted to estimate the main jamming parameters by investigating the discontinuousness of the ISRJ’s time-frequency (TF) characteristics. Then, a parameter-adjusted intra-pulse frequency coded signal, whose ISRJ signal after matched filtering only forms a single false target, is designed adaptively according to the estimated parameters, i.e., sampling interval, sampling duration and repeater times. Ultimately, for typical jamming scenes with different jamming signal ratio (JSR) and duty cycle, we propose two particular ISRJ suppression approaches. Simulation results validate the effective performance of the proposed scheme for countering the ISRJ, and the trade-off relationship between the two approaches is demonstrated. PMID:29642508

CFO compensation method using optical feedback path for coherent optical OFDM system

NASA Astrophysics Data System (ADS)

Moon, Sang-Rok; Hwang, In-Ki; Kang, Hun-Sik; Chang, Sun Hyok; Lee, Seung-Woo; Lee, Joon Ki

2017-07-01

We investigate feasibility of carrier frequency offset (CFO) compensation method using optical feedback path for coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. Recently proposed CFO compensation algorithms provide wide CFO estimation range in electrical domain. However, their practical compensation range is limited by sampling rate of an analog-to-digital converter (ADC). This limitation has not drawn attention, since the ADC sampling rate was high enough comparing to the data bandwidth and CFO in the wireless OFDM system. For CO-OFDM, the limitation is becoming visible because of increased data bandwidth, laser instability (i.e. large CFO) and insufficient ADC sampling rate owing to high cost. To solve the problem and extend practical CFO compensation range, we propose a CFO compensation method having optical feedback path. By adding simple wavelength control for local oscillator, the practical CFO compensation range can be extended to the sampling frequency range. The feasibility of the proposed method is experimentally investigated.

Probing dynamics of micro-magnets with multi-mode superconducting resonator

NASA Astrophysics Data System (ADS)

Golovchanskiy, I. A.; Abramov, N. N.; Stolyarov, V. S.; Shchetinin, I. V.; Dzhumaev, P. S.; Averkin, A. S.; Kozlov, S. N.; Golubov, A. A.; Ryazanov, V. V.; Ustinov, A. V.

2018-05-01

In this work, we propose and explore a sensitive technique for investigation of ferromagnetic resonance and corresponding magnetic properties of individual micro-scaled and/or weak ferromagnetic samples. The technique is based on coupling the investigated sample to a high-Q transmission line superconducting resonator, where the response of the sample is studied at eigen frequencies of the resonator. The high quality factor of the resonator enables sensitive detection of weak absorption losses at multiple frequencies of the ferromagnetic resonance. Studying the microwave response of individual micro-scaled permalloy rectangles, we have confirmed the superiority of fluxometric demagnetizing factor over the commonly accepted magnetometric one and have depicted the demagnetization of the sample, as well as magnetostatic standing wave resonance.

Frequency of EGFR T790M mutation and multimutational profiles of rebiopsy samples from non-small cell lung cancer developing acquired resistance to EGFR tyrosine kinase inhibitors in Japanese patients.

PubMed

Ko, Ryo; Kenmotsu, Hirotsugu; Serizawa, Masakuni; Koh, Yasuhiro; Wakuda, Kazushige; Ono, Akira; Taira, Tetsuhiko; Naito, Tateaki; Murakami, Haruyasu; Isaka, Mitsuhiro; Endo, Masahiro; Nakajima, Takashi; Ohde, Yasuhisa; Yamamoto, Nobuyuki; Takahashi, Kazuhisa; Takahashi, Toshiaki

2016-11-08

The majority of non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation eventually develop resistance to EGFR tyrosine kinase inhibitors (TKIs). Minimal information exists regarding genetic alterations in rebiopsy samples from Asian NSCLC patients who develop acquired resistance to EGFR-TKIs. We retrospectively reviewed the medical records of patients with NSCLC harboring EGFR mutations who had undergone rebiopsies after developing acquired resistance to EGFR-TKIs. We analyzed 27 practicable samples using a tumor genotyping panel to assess 23 hot-spot sites of genetic alterations in nine genes (EGFR, KRAS, BRAF, PIK3CA, NRAS, MEK1, AKT1, PTEN, and HER2), gene copy number of EGFR, MET, PIK3CA, FGFR1, and FGFR2, and ALK, ROS1, and RET fusions. Additionally, 34 samples were analyzed by commercially available EGFR mutation tests. Sixty-one patients underwent rebiopsy. Twenty-seven samples were analyzed using our tumor genotyping panel, and 34 samples were analyzed for EGFR mutations only by commercial clinical laboratories. Twenty-one patients (34 %) had EGFR T790M mutation. Using our tumor genotyping panel, MET gene copy number gain was observed in two of 27 (7 %) samples. Twenty patients received continuous treatment with EGFR-TKIs even after disease progression, and 11 of these patients had T790M mutation in rebiopsy samples. In contrast, only 10 of 41 patients who finished EGFR-TKI treatment at disease progression had T790M mutation. The frequency of T790M mutation in patients who received continuous treatment with EGFR-TKIs after disease progression was significantly higher than that in patients who finished EGFR-TKI treatment at disease progression (55 % versus 24 %, p = 0.018). The frequency of T790M mutation in this study was lower than that in previous reports examining western patients. These results suggest that continuous treatment with EGFR-TKI after disease progression may enhance the frequency of EGFR T790M mutation in rebiopsy samples.

Electrical and magnetic properties of rock and soil

USGS Publications Warehouse

Scott, J.H.

1983-01-01

Field and laboratory measurements have been made to determine the electrical conductivity, dielectric constant, and magnetic permeability of rock and soil in areas of interest in studies of electromagnetic pulse propagation. Conductivity is determined by making field measurements of apparent resisitivity at very low frequencies (0-20 cps), and interpreting the true resistivity of layers at various depths by curve-matching methods. Interpreted resistivity values are converted to corresponding conductivity values which are assumed to be applicable at 10^2 cps, an assumption which is considered valid because the conductivity of rock and soil is nearly constant at frequencies below 10^2 cps. Conductivity is estimated at higher frequencies (up to 10^6 cps) by using statistical correlations of three parameters obtained from laboratory measurements of rock and soil samples: conductivity at 10^2 cps, frequency and conductivity measured over the range 10^2 to 10^6 cps. Conductivity may also be estimated in this frequency range by using field measurements of water content and correlations of laboratory sample measurements of the three parameters: water content, frequency, and conductivity measured over the range 10^2 to 10^6 cps. This method is less accurate because nonrandom variation of ion concentration in natural pore water introduces error. Dielectric constant is estimated in a similar manner from field-derived conductivity values applicable at 10^2 cps and statistical correlations of three parameters obtained from laboratory measurements of samples: conductivity measured at 10^2 cps, frequency, and dielectric constant measured over the frequency range 10^2 to 10^6 cps. Dielectric constant may also be estimated from field measurements of water content and correlations of laboratory sample measurements of the three parameters: water content, frequency, and dielectric constant measured from 10^2 to 10^6 cps, but again, this method is less accurate because of variation of ion concentration of pore water. Special laboratory procedures are used to measure conductivity and dielectric constant of rock and soil samples. Electrode polarization errors are minimized by using an electrode system that is electrochemically reversible-with ions in pore water.

Random phase detection in multidimensional NMR.

PubMed

Maciejewski, Mark W; Fenwick, Matthew; Schuyler, Adam D; Stern, Alan S; Gorbatyuk, Vitaliy; Hoch, Jeffrey C

2011-10-04

Despite advances in resolution accompanying the development of high-field superconducting magnets, biomolecular applications of NMR require multiple dimensions in order to resolve individual resonances, and the achievable resolution is typically limited by practical constraints on measuring time. In addition to the need for measuring long evolution times to obtain high resolution, the need to distinguish the sign of the frequency constrains the ability to shorten measuring times. Sign discrimination is typically accomplished by sampling the signal with two different receiver phases or by selecting a reference frequency outside the range of frequencies spanned by the signal and then sampling at a higher rate. In the parametrically sampled (indirect) time dimensions of multidimensional NMR experiments, either method imposes an additional factor of 2 sampling burden for each dimension. We demonstrate that by using a single detector phase at each time sample point, but randomly altering the phase for different points, the sign ambiguity that attends fixed single-phase detection is resolved. Random phase detection enables a reduction in experiment time by a factor of 2 for each indirect dimension, amounting to a factor of 8 for a four-dimensional experiment, albeit at the cost of introducing sampling artifacts. Alternatively, for fixed measuring time, random phase detection can be used to double resolution in each indirect dimension. Random phase detection is complementary to nonuniform sampling methods, and their combination offers the potential for additional benefits. In addition to applications in biomolecular NMR, random phase detection could be useful in magnetic resonance imaging and other signal processing contexts.

Low-frequency creep in CoNiFe films.

NASA Technical Reports Server (NTRS)

Bartran, D. S.; Bourne, H. C., Jr.; Chow, L. G.

1972-01-01

Domain wall motion excited by slow rise-time, bipolar, hard-axis pulses in vacuum deposited CoNiFe films from 1500 to 2000 A thick is studied. The results are consistent with those of comparable NiFe films. Furthermore, the wall coercivity is found to be the most significant sample property correlated to the low-frequency creep properties of all the samples.

AC conductivity, magnetic and shielding effectiveness studies on polyaniline embedded Co0.5Mn0.5Fe2O4 nanoparticles for electromagnetic interference suppression

NASA Astrophysics Data System (ADS)

Gurusiddesh, M.; Madhu, B. J.; Shankaramurthy, G. J.

2018-05-01

Electrically conducting Polyaniline (PANI)/Co0.5Mn0.5Fe2O4 nanocomposites are synthesized by in situ polymerization of aniline monomer in the presence of Co0.5Mn0.5Fe2O4 nanoparticles. Structural studies on the synthesized samples have been carried out using X-ray diffraction technique, Field emission scanning electron microscopy and Energy dispersive X-ray spectroscopy. Frequency dependent ac conductivity studies on the prepared samples revealed that conductivity of the composite is high compared to Co0.5Mn0.5Fe2O4 nanoparticles. Further, both the samples exhibited hysteresis behavior under the applied magnetic field. Electromagnetic interference (EMI) shielding effectiveness of both the samples decreases with increase in the applied frequency in the studied frequency range. Maximum shielding effectiveness (SE) of 31.49 dB and 62.84 dB were obtained for Co0.5Mn0.5Fe2O4 nanoparticles and PANI/Co0.5Mn0.5Fe2O4 nanocomposites respectively in the studied frequency range. Observed higher EMI shielding in the composites was attributed to its high electrical conductivity.

Influence of ECG sampling rate in fetal heart rate variability analysis.

PubMed

De Jonckheere, J; Garabedian, C; Charlier, P; Champion, C; Servan-Schreiber, E; Storme, L; Debarge, V; Jeanne, M; Logier, R

2017-07-01

Fetal hypoxia results in a fetal blood acidosis (pH<;7.10). In such a situation, the fetus develops several adaptation mechanisms regulated by the autonomic nervous system. Many studies demonstrated significant changes in heart rate variability in hypoxic fetuses. So, fetal heart rate variability analysis could be of precious help for fetal hypoxia prediction. Commonly used fetal heart rate variability analysis methods have been shown to be sensitive to the ECG signal sampling rate. Indeed, a low sampling rate could induce variability in the heart beat detection which will alter the heart rate variability estimation. In this paper, we introduce an original fetal heart rate variability analysis method. We hypothesize that this method will be less sensitive to ECG sampling frequency changes than common heart rate variability analysis methods. We then compared the results of this new heart rate variability analysis method with two different sampling frequencies (250-1000 Hz).

The Estimation of Tree Posterior Probabilities Using Conditional Clade Probability Distributions

PubMed Central

Larget, Bret

2013-01-01

In this article I introduce the idea of conditional independence of separated subtrees as a principle by which to estimate the posterior probability of trees using conditional clade probability distributions rather than simple sample relative frequencies. I describe an algorithm for these calculations and software which implements these ideas. I show that these alternative calculations are very similar to simple sample relative frequencies for high probability trees but are substantially more accurate for relatively low probability trees. The method allows the posterior probability of unsampled trees to be calculated when these trees contain only clades that are in other sampled trees. Furthermore, the method can be used to estimate the total probability of the set of sampled trees which provides a measure of the thoroughness of a posterior sample. [Bayesian phylogenetics; conditional clade distributions; improved accuracy; posterior probabilities of trees.] PMID:23479066

Method for utilizing properties of the sinc(x) function for phase retrieval on nyquist-under-sampled data

NASA Technical Reports Server (NTRS)

Dean, Bruce H. (Inventor); Smith, Jeffrey Scott (Inventor); Aronstein, David L. (Inventor)

2012-01-01

Disclosed herein are systems, methods, and non-transitory computer-readable storage media for simulating propagation of an electromagnetic field, performing phase retrieval, or sampling a band-limited function. A system practicing the method generates transformed data using a discrete Fourier transform which samples a band-limited function f(x) without interpolating or modifying received data associated with the function f(x), wherein an interval between repeated copies in a periodic extension of the function f(x) obtained from the discrete Fourier transform is associated with a sampling ratio Q, defined as a ratio of a sampling frequency to a band-limited frequency, and wherein Q is assigned a value between 1 and 2 such that substantially no aliasing occurs in the transformed data, and retrieves a phase in the received data based on the transformed data, wherein the phase is used as feedback to an optical system.

Representativeness-based sampling network design for the State of Alaska

Treesearch

Forrest M. Hoffman; Jitendra Kumar; Richard T. Mills; William W. Hargrove

2013-01-01

Resource and logistical constraints limit the frequency and extent of environmental observations, particularly in the Arctic, necessitating the development of a systematic sampling strategy to maximize coverage and objectively represent environmental variability at desired scales. A quantitative methodology for stratifying sampling domains, informing site selection,...

Asymmetrical booster ascent guidance and control system design study. Volume 4: Sampled data stability analysis program (SADSAP) user's guide. [space shuttle development

NASA Technical Reports Server (NTRS)

Wilson, J. L.

1974-01-01

A users guide to the Sampled Data Stability Analysis Program (SADSAP) is provided. This program is a general purpose sampled data Stability Analysis Program capable of providing frequency response on root locus data.

[Distribution of DRD4 and DAT1 alleles from dopaminergic system in a mixed Chilean population].

PubMed

Vieyra, Gonzalo; Moraga, Mauricio; Henríquez, Hugo; Aboitiz, Francisco; Rothhammer, Francisco

2003-02-01

Genes for dopamine receptor DRD4 and dopamine transporter DAT1 are highly polymorphic. Two alleles of these genes, namely the DRD4.7 and the DAT1*9 are frequently associated to the attention deficit disorder with hyperactivity. In Europe, the allele for DRD4 receptor with four repetitions (DRD4.4) has the highest frequency, with a median of 69%, followed by DRD4.7, with a frequency of 15%. South American indigenous populations have higher frequencies for DRD4.7 (61%) than for DRD4.4 (29%). The ten repetition allele for DAT1 transporter has a high frequency among Europeans (72%) and Amerindians (100%). The allele DAT1*9 is the second most frequent allele. To study the frequency of DRD4 and DAT1 alleles in a Chilean population sample. One hundred serum samples were obtained from blood donors in two public hospitals in Santiago. Polymorphic regions for DRD4 and DAT1 were amplified by polymerase chain reaction. The allele DRD4.4 had a frequency of 59% and DRD4.7 a frequency of 27%. The allele DAT1*10 had a frequency of 74%, followed by DAT 1*9, with a frequency of 23%. In a Chilean population sample, the frequency of DRD4 and DAT1 alleles was very similar to that of European populations.

Sensitive Metamaterial Sensor for Distinction of Authentic and Inauthentic Fuel Samples

NASA Astrophysics Data System (ADS)

Tümkaya, Mehmet Ali; Dinçer, Furkan; Karaaslan, Muharrem; Sabah, Cumali

2017-08-01

A metamaterial-based sensor has been realized to distinguish authentic and inauthentic fuel samples in the microwave frequency regime. Unlike the many studies in literature on metamaterial-based sensor applications, this study focuses on a compact metamaterial-based sensor operating in the X-band frequency range. Firstly, electromagnetic properties of authentic and inauthentic fuel samples were obtained experimentally in a laboratory environment. Secondly, these experimental results were used to design and create a highly efficient metamaterial-based sensor with easy fabrication characteristics and simple design structure. The experimental results for the sensor were in good agreement with the numerical ones. The proposed sensor offers a more efficient design and can be used to detect fuel and multiple other liquids in various application fields from medical to military areas in several frequency regimes.

A study on the co- and adjacent channel protection requirements for mobile satellite ACSSB modulation

NASA Technical Reports Server (NTRS)

Sydor, John T.

1988-01-01

Samples of speech modulated by narrowband frequency modulation (NBFM) (cellular) and amplitude companded single sideband (ACSSB) radios were subjected to simulated co- and adjacent channel interference environments typical of proposed frequency division multiple access (FDMA) mobile satellite systems. These samples were then listened to by a group of evaluators whose subjective responses to the samples were used to produce a series of graphs showing the relationship between subjective acceptability, carrier to noise density (C/No), carrier to interference ratio (C/I), and frequency offset. The results show that in a mobile satellite environment, ACSSB deteriorates more slowly than NBFM. The co- and adjacent channel protection ratios for both modulation techniques were roughly the same, even though the mechanism for signal deterioration is different.

Transition to collective oscillations in finite Kuramoto ensembles

NASA Astrophysics Data System (ADS)

Peter, Franziska; Pikovsky, Arkady

2018-03-01

We present an alternative approach to finite-size effects around the synchronization transition in the standard Kuramoto model. Our main focus lies on the conditions under which a collective oscillatory mode is well defined. For this purpose, the minimal value of the amplitude of the complex Kuramoto order parameter appears as a proper indicator. The dependence of this minimum on coupling strength varies due to sampling variations and correlates with the sample kurtosis of the natural frequency distribution. The skewness of the frequency sample determines the frequency of the resulting collective mode. The effects of kurtosis and skewness hold in the thermodynamic limit of infinite ensembles. We prove this by integrating a self-consistency equation for the complex Kuramoto order parameter for two families of distributions with controlled kurtosis and skewness, respectively.

Dynamic nuclear polarization using frequency modulation at 3.34 T.

PubMed

Hovav, Y; Feintuch, A; Vega, S; Goldfarb, D

2014-01-01

During dynamic nuclear polarization (DNP) experiments polarization is transferred from unpaired electrons to their neighboring nuclear spins, resulting in dramatic enhancement of the NMR signals. While in most cases this is achieved by continuous wave (cw) irradiation applied to samples in fixed external magnetic fields, here we show that DNP enhancement of static samples can improve by modulating the microwave (MW) frequency at a constant field of 3.34 T. The efficiency of triangular shaped modulation is explored by monitoring the (1)H signal enhancement in frozen solutions containing different TEMPOL radical concentrations at different temperatures. The optimal modulation parameters are examined experimentally and under the most favorable conditions a threefold enhancement is obtained with respect to constant frequency DNP in samples with low radical concentrations. The results are interpreted using numerical simulations on small spin systems. In particular, it is shown experimentally and explained theoretically that: (i) The optimal modulation frequency is higher than the electron spin-lattice relaxation rate. (ii) The optimal modulation amplitude must be smaller than the nuclear Larmor frequency and the EPR line-width, as expected. (iii) The MW frequencies corresponding to the enhancement maxima and minima are shifted away from one another when using frequency modulation, relative to the constant frequency experiments. Copyright © 2013 Elsevier Inc. All rights reserved.

Vapor concentration monitor

DOEpatents

Bayly, John G.; Booth, Ronald J.

1977-01-01

An apparatus for monitoring the concentration of a vapor, such as heavy water, having at least one narrow bandwidth in its absorption spectrum, in a sample gas such as air. The air is drawn into a chamber in which the vapor content is measured by means of its radiation absorption spectrum. High sensitivity is obtained by modulating the wavelength at a relatively high frequency without changing its optical path, while high stability against zero drift is obtained by the low frequency interchange of the sample gas to be monitored and of a reference sample. The variable HDO background due to natural humidity is automatically corrected.

Apparatus and method for measuring electrostatic polarization

DOEpatents

Hahn, Erwin L.; Clarke, John; Sloater, Tycho; Hilbert, Claude; Heaney, Michael B.

1989-01-01

An apparatus and method for measuring the electric properties of solid matter which provides data for determining the polarizability of the electron distributions contained therein is disclosed. A sample of the solid to be studied is placed between the plates of a capacitor where it acts as a dielectric. The sample is excited by the interaction of electromagnetic radiation with an atomic species contained in the sample. The voltage induced across the capacitor is then measured as a function of time with the aid of a high Q circuit tuned to a frequency related to the frequency of the applied electromagnetic energy.

Apparatus and method for measuring fluorescence intensities at a plurality of wavelengths and lifetimes

DOEpatents

Buican, T.N.

1993-05-04

Apparatus and method is described for measuring intensities at a plurality of wavelengths and lifetimes. A source of multiple-wavelength electromagnetic radiation is passed through a first interferometer modulated at a first frequency, the output thereof being directed into a sample to be investigated. The light emitted from the sample as a result of the interaction thereof with the excitation radiation is directed into a second interferometer modulated at a second frequency, and the output detected and analyzed. In this manner excitation, emission, and lifetime information may be obtained for a multiplicity of fluorochromes in the sample.

Selectivity enhancement in photoacoustic gas analysis via phase-sensitive detection at high modulation frequency

NASA Technical Reports Server (NTRS)

Kosterev, Anatoliy (Inventor)

2010-01-01

A method for detecting a target fluid in a fluid sample comprising a first fluid and the target fluid using photoacoustic spectroscopy (PAS), comprises a) providing a light source configured to introduce an optical signal having at least one wavelength into the fluid sample; b) modulating the optical signal at a desired modulation frequency such that the optical signal generates an acoustic signal in the fluid sample; c) measuring the acoustic signal in a resonant acoustic detector; and d) using the phase of the acoustic signal to detect the presence of the target fluid.

Continuous- and discrete-time stimulus sequences for high stimulus rate paradigm in evoked potential studies.

PubMed

Wang, Tao; Huang, Jiang-hua; Lin, Lin; Zhan, Chang'an A

2013-01-01

To obtain reliable transient auditory evoked potentials (AEPs) from EEGs recorded using high stimulus rate (HSR) paradigm, it is critical to design the stimulus sequences of appropriate frequency properties. Traditionally, the individual stimulus events in a stimulus sequence occur only at discrete time points dependent on the sampling frequency of the recording system and the duration of stimulus sequence. This dependency likely causes the implementation of suboptimal stimulus sequences, sacrificing the reliability of resulting AEPs. In this paper, we explicate the use of continuous-time stimulus sequence for HSR paradigm, which is independent of the discrete electroencephalogram (EEG) recording system. We employ simulation studies to examine the applicability of the continuous-time stimulus sequences and the impacts of sampling frequency on AEPs in traditional studies using discrete-time design. Results from these studies show that the continuous-time sequences can offer better frequency properties and improve the reliability of recovered AEPs. Furthermore, we find that the errors in the recovered AEPs depend critically on the sampling frequencies of experimental systems, and their relationship can be fitted using a reciprocal function. As such, our study contributes to the literature by demonstrating the applicability and advantages of continuous-time stimulus sequences for HSR paradigm and by revealing the relationship between the reliability of AEPs and sampling frequencies of the experimental systems when discrete-time stimulus sequences are used in traditional manner for the HSR paradigm.

Estimating species - area relationships by modeling abundance and frequency subject to incomplete sampling.

PubMed

Yamaura, Yuichi; Connor, Edward F; Royle, J Andrew; Itoh, Katsuo; Sato, Kiyoshi; Taki, Hisatomo; Mishima, Yoshio

2016-07-01

Models and data used to describe species-area relationships confound sampling with ecological process as they fail to acknowledge that estimates of species richness arise due to sampling. This compromises our ability to make ecological inferences from and about species-area relationships. We develop and illustrate hierarchical community models of abundance and frequency to estimate species richness. The models we propose separate sampling from ecological processes by explicitly accounting for the fact that sampled patches are seldom completely covered by sampling plots and that individuals present in the sampling plots are imperfectly detected. We propose a multispecies abundance model in which community assembly is treated as the summation of an ensemble of species-level Poisson processes and estimate patch-level species richness as a derived parameter. We use sampling process models appropriate for specific survey methods. We propose a multispecies frequency model that treats the number of plots in which a species occurs as a binomial process. We illustrate these models using data collected in surveys of early-successional bird species and plants in young forest plantation patches. Results indicate that only mature forest plant species deviated from the constant density hypothesis, but the null model suggested that the deviations were too small to alter the form of species-area relationships. Nevertheless, results from simulations clearly show that the aggregate pattern of individual species density-area relationships and occurrence probability-area relationships can alter the form of species-area relationships. The plant community model estimated that only half of the species present in the regional species pool were encountered during the survey. The modeling framework we propose explicitly accounts for sampling processes so that ecological processes can be examined free of sampling artefacts. Our modeling approach is extensible and could be applied to a variety of study designs and allows the inclusion of additional environmental covariates.

Fate of organic microcontaminants in wastewater treatment and river systems: An uncertainty assessment in view of sampling strategy, and compound consumption rate and degradability.

PubMed

Aymerich, I; Acuña, V; Ort, C; Rodríguez-Roda, I; Corominas, Ll

2017-11-15

The growing awareness of the relevance of organic microcontaminants on the environment has led to a growing number of studies on attenuation of these compounds in wastewater treatment plants (WWTP) and rivers. However, the effects of the sampling strategies (frequency and duration of composite samples) on the attenuation estimates are largely unknown. Our goal was to assess how frequency and duration of composite samples influence uncertainty of the attenuation estimates in WWTPs and rivers. Furthermore, we also assessed how compound consumption rate and degradability influence uncertainty. The assessment was conducted through simulating the integrated wastewater system of Puigcerdà (NE Iberian Peninsula) using a sewer pattern generator and a coupled model of WWTP and river. Results showed that the sampling strategy is especially critical at the influent of WWTP, particularly when the number of toilet flushes containing the compound of interest is small (≤100 toilet flushes with compound day -1 ), and less critical at the effluent of the WWTP and in the river due to the mixing effects of the WWTP. For example, at the WWTP, when evaluating a compound that is present in 50 pulses·d -1 using a sampling frequency of 15-min to collect a 24-h composite sample, the attenuation uncertainty can range from 94% (0% degradability) to 9% (90% degradability). The estimation of attenuation in rivers is less critical than in WWTPs, as the attenuation uncertainty was lower than 10% for all evaluated scenarios. Interestingly, the errors in the estimates of attenuation are usually lower than those of loads for most sampling strategies and compound characteristics (e.g. consumption and degradability), although the opposite occurs for compounds with low consumption and inappropriate sampling strategies at the WWTP. Hence, when designing a sampling campaign, one should consider the influence of compounds' consumption and degradability as well as the desired level of accuracy in attenuation estimations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Estimating species – area relationships by modeling abundance and frequency subject to incomplete sampling

USGS Publications Warehouse

Yamaura, Yuichi; Connor, Edward F.; Royle, Andy; Itoh, Katsuo; Sato, Kiyoshi; Taki, Hisatomo; Mishima, Yoshio

2016-01-01

Models and data used to describe species–area relationships confound sampling with ecological process as they fail to acknowledge that estimates of species richness arise due to sampling. This compromises our ability to make ecological inferences from and about species–area relationships. We develop and illustrate hierarchical community models of abundance and frequency to estimate species richness. The models we propose separate sampling from ecological processes by explicitly accounting for the fact that sampled patches are seldom completely covered by sampling plots and that individuals present in the sampling plots are imperfectly detected. We propose a multispecies abundance model in which community assembly is treated as the summation of an ensemble of species-level Poisson processes and estimate patch-level species richness as a derived parameter. We use sampling process models appropriate for specific survey methods. We propose a multispecies frequency model that treats the number of plots in which a species occurs as a binomial process. We illustrate these models using data collected in surveys of early-successional bird species and plants in young forest plantation patches. Results indicate that only mature forest plant species deviated from the constant density hypothesis, but the null model suggested that the deviations were too small to alter the form of species–area relationships. Nevertheless, results from simulations clearly show that the aggregate pattern of individual species density–area relationships and occurrence probability–area relationships can alter the form of species–area relationships. The plant community model estimated that only half of the species present in the regional species pool were encountered during the survey. The modeling framework we propose explicitly accounts for sampling processes so that ecological processes can be examined free of sampling artefacts. Our modeling approach is extensible and could be applied to a variety of study designs and allows the inclusion of additional environmental covariates.

Powder Handling Device for Analytical Instruments

NASA Technical Reports Server (NTRS)

Sarrazin, Philippe C. (Inventor); Blake, David F. (Inventor)

2006-01-01

Method and system for causing a powder sample in a sample holder to undergo at least one of three motions (vibration, rotation and translation) at a selected motion frequency in order to present several views of an individual grain of the sample. One or more measurements of diffraction, fluorescence, spectroscopic interaction, transmission, absorption and/or reflection can be made on the sample, using light in a selected wavelength region.

Assessing the precision of a time-sampling-based study among GPs: balancing sample size and measurement frequency.

PubMed

van Hassel, Daniël; van der Velden, Lud; de Bakker, Dinny; van der Hoek, Lucas; Batenburg, Ronald

2017-12-04

Our research is based on a technique for time sampling, an innovative method for measuring the working hours of Dutch general practitioners (GPs), which was deployed in an earlier study. In this study, 1051 GPs were questioned about their activities in real time by sending them one SMS text message every 3 h during 1 week. The required sample size for this study is important for health workforce planners to know if they want to apply this method to target groups who are hard to reach or if fewer resources are available. In this time-sampling method, however, standard power analyses is not sufficient for calculating the required sample size as this accounts only for sample fluctuation and not for the fluctuation of measurements taken from every participant. We investigated the impact of the number of participants and frequency of measurements per participant upon the confidence intervals (CIs) for the hours worked per week. Statistical analyses of the time-use data we obtained from GPs were performed. Ninety-five percent CIs were calculated, using equations and simulation techniques, for various different numbers of GPs included in the dataset and for various frequencies of measurements per participant. Our results showed that the one-tailed CI, including sample and measurement fluctuation, decreased from 21 until 3 h between one and 50 GPs. As a result of the formulas to calculate CIs, the increase of the precision continued and was lower with the same additional number of GPs. Likewise, the analyses showed how the number of participants required decreased if more measurements per participant were taken. For example, one measurement per 3-h time slot during the week requires 300 GPs to achieve a CI of 1 h, while one measurement per hour requires 100 GPs to obtain the same result. The sample size needed for time-use research based on a time-sampling technique depends on the design and aim of the study. In this paper, we showed how the precision of the measurement of hours worked each week by GPs strongly varied according to the number of GPs included and the frequency of measurements per GP during the week measured. The best balance between both dimensions will depend upon different circumstances, such as the target group and the budget available.

THE COMPREHENSION OF RAPID SPEECH BY THE BLIND, PART III.

ERIC Educational Resources Information Center

FOULKE, EMERSON

A REVIEW OF THE RESEARCH ON THE COMPREHENSION OF RAPID SPEECH BY THE BLIND IDENTIFIES FIVE METHODS OF SPEECH COMPRESSION--SPEECH CHANGING, ELECTROMECHANICAL SAMPLING, COMPUTER SAMPLING, SPEECH SYNTHESIS, AND FREQUENCY DIVIDING WITH THE HARMONIC COMPRESSOR. THE SPEECH CHANGING AND ELECTROMECHANICAL SAMPLING METHODS AND THE NECESSARY APPARATUS HAVE…

Irritability without Elation in a Large Bipolar Youth Sample: Frequency and Clinical Description

ERIC Educational Resources Information Center

Hunt, Jeffrey; Birmaher, Boris; Leonard, Henrietta; Strober, Michael; Axelson, David; Ryan, Neal; Yang, Mei; Gill, Marykay; Dyl, Jennifer; Esposito-Smythers, Christianne; Swenson, Lance; Goldstein, Benjamin; Goldstein, Tina; Stout, Robert; Keller, Martin

2009-01-01

The assessment of 361 youths with bipolar disorder reveal that irritable-only subgroups constitute 10 percent of this sample while elated-only subgroups constitute 15 percent of the sample. These findings support continued consideration for episodic irritability in the diagnosis of pediatric bipolar disorder.

Fast temporal fluctuations in single-molecule junctions.

PubMed

Ochs, Roif; Secker, Daniel; Elbing, Mark; Mayor, Marcel; Weber, Heiko B

2006-01-01

The noise within the electrical current through single-molecule junctions is studied cryogenic temperature. The organic sample molecules were contacted with the mechanically controlled break-junction technique. The noise spectra refer to a where only few Lorentzian fluctuators occur in the conductance. The frequency dependence shows qualitative variations from sample to sample.

Digital Receiver Phase Meter

NASA Technical Reports Server (NTRS)

Marcin, Martin; Abramovici, Alexander

2008-01-01

The software of a commercially available digital radio receiver has been modified to make the receiver function as a two-channel low-noise phase meter. This phase meter is a prototype in the continuing development of a phase meter for a system in which radiofrequency (RF) signals in the two channels would be outputs of a spaceborne heterodyne laser interferometer for detecting gravitational waves. The frequencies of the signals could include a common Doppler-shift component of as much as 15 MHz. The phase meter is required to measure the relative phases of the signals in the two channels at a sampling rate of 10 Hz at a root power spectral density <5 microcycle/(Hz)1/2 and to be capable of determining the power spectral density of the phase difference over the frequency range from 1 mHz to 1 Hz. Such a phase meter could also be used on Earth to perform similar measurements in laser metrology of moving bodies. To illustrate part of the principle of operation of the phase meter, the figure includes a simplified block diagram of a basic singlechannel digital receiver. The input RF signal is first fed to the input terminal of an analog-to-digital converter (ADC). To prevent aliasing errors in the ADC, the sampling rate must be at least twice the input signal frequency. The sampling rate of the ADC is governed by a sampling clock, which also drives a digital local oscillator (DLO), which is a direct digital frequency synthesizer. The DLO produces samples of sine and cosine signals at a programmed tuning frequency. The sine and cosine samples are mixed with (that is, multiplied by) the samples from the ADC, then low-pass filtered to obtain in-phase (I) and quadrature (Q) signal components. A digital signal processor (DSP) computes the ratio between the Q and I components, computes the phase of the RF signal (relative to that of the DLO signal) as the arctangent of this ratio, and then averages successive such phase values over a time interval specified by the user.

Seismic wave attenuation and velocity dispersion in UAE carbonates

NASA Astrophysics Data System (ADS)

Ogunsami, Abdulwaheed Remi

Interpreting the seismic property of fluids in hydrocarbon reservoirs at low frequency scale has been a cherished goal of petroleum geophysics research for decades. Lately, there has been tremendous interest in understanding attenuation as a result of fluid flow in porous media. Although interesting, the emerging experimental and theoretical information still remain ambiguous and are practically not utilized for reasons not too obscure. Attenuation is frequency dependent and hard to measure in the laboratory at low frequency. This thesis describes and reports the results of an experimental study of low frequency attenuation and velocity dispersion on a selected carbonate reservoir samples in the United Arab Emirates (UAE). For the low frequency measurements, stress-strain method was used to measure the moduli from which the velocity is derived. Attenuation was measured as the phase difference between the applied stress and the strain. For the ultrasonic component, the pulse propagation method was employed. To study the fluid effect especially at reservoir in situ conditions, the measurements were made dry and saturated with liquid butane and brine at differential pressures of up to 5000 psi with pore pressure held constant at 500 psi. Similarly to what has been documented in the literatures for sandstone, attenuation of the bulk compressibility mode dominates the losses in these dry and somewhat partially saturated carbonate samples with butane and brine. Overall, the observed attenuation cannot be simply said to be frequency dependent within this low seismic band. While attenuation seems to be practically constant in the low frequency band for sample 3H, such conclusion cannot be made for sample 7H. For the velocities, significant dispersion is observed and Gassmann generally fails to match the measured velocities. Only the squirt model fairly fits the velocities, but not at all pressures. Although the observed dispersion is larger than Biot's prediction, the fact that Squirt (Biot-Squirt and Gassmann-Squirt) over predicts the velocities at low pressure (e.g. Biot- Squirt from 500 psi for samples 7H, 8H and 10V) and under predicts at higher pressures (e.g. Gassman squirt beyond 1000 Psi to as high as 3500 psi for 10V and 7V) suggests that the Squirt model seems to contribute to the overall dispersion in these carbonate samples. In addition, although Gassmann fairly predicts some of the butane saturated velocity, it is not applicable for these carbonate samples when saturated with brine.

Noise and Complexity in Human Postural Control: Interpreting the Different Estimations of Entropy

PubMed Central

Rhea, Christopher K.; Silver, Tobin A.; Hong, S. Lee; Ryu, Joong Hyun; Studenka, Breanna E.; Hughes, Charmayne M. L.; Haddad, Jeffrey M.

2011-01-01

Background Over the last two decades, various measures of entropy have been used to examine the complexity of human postural control. In general, entropy measures provide information regarding the health, stability and adaptability of the postural system that is not captured when using more traditional analytical techniques. The purpose of this study was to examine how noise, sampling frequency and time series length influence various measures of entropy when applied to human center of pressure (CoP) data, as well as in synthetic signals with known properties. Such a comparison is necessary to interpret data between and within studies that use different entropy measures, equipment, sampling frequencies or data collection durations. Methods and Findings The complexity of synthetic signals with known properties and standing CoP data was calculated using Approximate Entropy (ApEn), Sample Entropy (SampEn) and Recurrence Quantification Analysis Entropy (RQAEn). All signals were examined at varying sampling frequencies and with varying amounts of added noise. Additionally, an increment time series of the original CoP data was examined to remove long-range correlations. Of the three measures examined, ApEn was the least robust to sampling frequency and noise manipulations. Additionally, increased noise led to an increase in SampEn, but a decrease in RQAEn. Thus, noise can yield inconsistent results between the various entropy measures. Finally, the differences between the entropy measures were minimized in the increment CoP data, suggesting that long-range correlations should be removed from CoP data prior to calculating entropy. Conclusions The various algorithms typically used to quantify the complexity (entropy) of CoP may yield very different results, particularly when sampling frequency and noise are different. The results of this study are discussed within the context of the neural noise and loss of complexity hypotheses. PMID:21437281

Technique for Performing Dielectric Property Measurements at Microwave Frequencies

NASA Technical Reports Server (NTRS)

Barmatz, Martin B.; Jackson, Henry W.

2010-01-01

A paper discusses the need to perform accurate dielectric property measurements on larger sized samples, particularly liquids at microwave frequencies. These types of measurements cannot be obtained using conventional cavity perturbation methods, particularly for liquids or powdered or granulated solids that require a surrounding container. To solve this problem, a model has been developed for the resonant frequency and quality factor of a cylindrical microwave cavity containing concentric cylindrical samples. This model can then be inverted to obtain the real and imaginary dielectric constants of the material of interest. This approach is based on using exact solutions to Maxwell s equations for the resonant properties of a cylindrical microwave cavity and also using the effective electrical conductivity of the cavity walls that is estimated from the measured empty cavity quality factor. This new approach calculates the complex resonant frequency and associated electromagnetic fields for a cylindrical microwave cavity with lossy walls that is loaded with concentric, axially aligned, lossy dielectric cylindrical samples. In this approach, the calculated complex resonant frequency, consisting of real and imaginary parts, is related to the experimentally measured quantities. Because this approach uses Maxwell's equations to determine the perturbed electromagnetic fields in the cavity with the material(s) inserted, one can calculate the expected wall losses using the fields for the loaded cavity rather than just depending on the value of the fields obtained from the empty cavity quality factor. These additional calculations provide a more accurate determination of the complex dielectric constant of the material being studied. The improved approach will be particularly important when working with larger samples or samples with larger dielectric constants that will further perturb the cavity electromagnetic fields. Also, this approach enables the ability to have a larger sample of interest, such as a liquid or powdered or granulated solid, inside a cylindrical container.

Development and Validation of Pathogen Environmental Monitoring Programs for Small Cheese Processing Facilities.

PubMed

Beno, Sarah M; Stasiewicz, Matthew J; Andrus, Alexis D; Ralyea, Robert D; Kent, David J; Martin, Nicole H; Wiedmann, Martin; Boor, Kathryn J

2016-12-01

Pathogen environmental monitoring programs (EMPs) are essential for food processing facilities of all sizes that produce ready-to-eat food products exposed to the processing environment. We developed, implemented, and evaluated EMPs targeting Listeria spp. and Salmonella in nine small cheese processing facilities, including seven farmstead facilities. Individual EMPs with monthly sample collection protocols were designed specifically for each facility. Salmonella was detected in only one facility, with likely introduction from the adjacent farm indicated by pulsed-field gel electrophoresis data. Listeria spp. were isolated from all nine facilities during routine sampling. The overall Listeria spp. (other than Listeria monocytogenes ) and L. monocytogenes prevalences in the 4,430 environmental samples collected were 6.03 and 1.35%, respectively. Molecular characterization and subtyping data suggested persistence of a given Listeria spp. strain in seven facilities and persistence of L. monocytogenes in four facilities. To assess routine sampling plans, validation sampling for Listeria spp. was performed in seven facilities after at least 6 months of routine sampling. This validation sampling was performed by independent individuals and included collection of 50 to 150 samples per facility, based on statistical sample size calculations. Two of the facilities had a significantly higher frequency of detection of Listeria spp. during the validation sampling than during routine sampling, whereas two other facilities had significantly lower frequencies of detection. This study provides a model for a science- and statistics-based approach to developing and validating pathogen EMPs.

Characterization the microstructure of pulsed Nd:YAG welding method in low frequencies; correlation with tensile and fracture behavior in laser-welded nitinol joints

NASA Astrophysics Data System (ADS)

Shojaei Zoeram, Ali; Rahmani, Aida; Asghar Akbari Mousavi, Seyed Ali

2017-05-01

The precise controllability of heat input in pulsed Nd:YAG welding method provided by two additional parameters, frequency and pulse duration, has made this method very promising for welding of alloys sensitive to heat input. The poor weldability of Ti-rich nitinol as a result of the formation of Ti2Ni IMC has deprived us of the unique properties of this alloy. In this study, to intensify solidification rate during welding of Ti-rich nitinol, pulsed Nd:YAG laser beam in low frequency was employed in addition to the employment of a copper substrate. Specific microstructure produced in this condition was characterized and the effects of this microstructure on tensile and fracture behavior of samples welded by two different procedures, full penetration and double-sided method with halved penetration depth for each side were investigated. The investigations revealed although the combination of low frequencies, the use of a high thermal conductor substrate and double-sided method eliminated intergranular fracture and increased tensile strength, the particular microstructure, built in the pulsed welding method in low frequencies, results to the formation of the longitudinal cracks during the first stages of tensile test at weld centerline. This degrades tensile strength of welded samples compared to base metal. The results showed samples welded in double-sided method performed much better than samples welded in full penetration mode.

Experimental determination of the frequency and field dependence of Specific Loss Power in Magnetic Fluid Hyperthermia

NASA Astrophysics Data System (ADS)

Cobianchi, M.; Guerrini, A.; Avolio, M.; Innocenti, C.; Corti, M.; Arosio, P.; Orsini, F.; Sangregorio, C.; Lascialfari, A.

2017-12-01

Magnetic nanoparticles are promising systems for biomedical applications and in particular for Magnetic Fluid Hyperthermia, a therapy that utilizes the heat released by such systems to damage tumor cells. We present an experimental study of the physical properties that influences the capability of heat release, i.e. the Specific Loss Power, SLP, of three biocompatible ferrofluid samples having a magnetic core of maghemite with different diameter d = 10.2, 14.6 and 19.7 nm. The SLP was measured as a function of frequency f and intensity H of the applied alternating magnetic field, and it turned out to depend on the core diameter, as expected. The results allowed us to highlight experimentally that the physical mechanism responsible for the heating is size-dependent and to establish, at applied constant frequency, the phenomenological functional relationship SLP = c·Hx, with 2 ≤ x<3 for all samples. The x-value depends on sample size and field frequency, here chosen in the typical range of operating magnetic hyperthermia devices. For the smallest sample, the effective relaxation time τeff ≈ 19.5 ns obtained from SLP data is in agreement with the value estimated from magnetization data, thus confirming the validity of the Linear Response Theory model for this system at properly chosen field intensity and frequency.

Asynchronous signal-dependent non-uniform sampler

NASA Astrophysics Data System (ADS)

Can-Cimino, Azime; Chaparro, Luis F.; Sejdić, Ervin

2014-05-01

Analog sparse signals resulting from biomedical and sensing network applications are typically non-stationary with frequency-varying spectra. By ignoring that the maximum frequency of their spectra is changing, uniform sampling of sparse signals collects unnecessary samples in quiescent segments of the signal. A more appropriate sampling approach would be signal-dependent. Moreover, in many of these applications power consumption and analog processing are issues of great importance that need to be considered. In this paper we present a signal dependent non-uniform sampler that uses a Modified Asynchronous Sigma Delta Modulator which consumes low-power and can be processed using analog procedures. Using Prolate Spheroidal Wave Functions (PSWF) interpolation of the original signal is performed, thus giving an asynchronous analog to digital and digital to analog conversion. Stable solutions are obtained by using modulated PSWFs functions. The advantage of the adapted asynchronous sampler is that range of frequencies of the sparse signal is taken into account avoiding aliasing. Moreover, it requires saving only the zero-crossing times of the non-uniform samples, or their differences, and the reconstruction can be done using their quantized values and a PSWF-based interpolation. The range of frequencies analyzed can be changed and the sampler can be implemented as a bank of filters for unknown range of frequencies. The performance of the proposed algorithm is illustrated with an electroencephalogram (EEG) signal.

Effects of temperature, moisture, and metal salt content on dielectric properties of rice bran associated with radio frequency heating.

PubMed

Ling, Bo; Liu, Xiaoli; Zhang, Lihui; Wang, Shaojin

2018-03-13

Dielectric heating including microwave (MW) and radio frequency (RF) energy has been regarded as alternative thermal treatments for food processing. To develop effective rice bran (RB) stabilization treatments based on RF and MW heating, dielectric properties (DPs) with dielectric constant (ε') and loss factor (ε″) of RB samples at frequencies (10-3000 MHz), temperatures (25-100 °C), moisture content (MC, 10.36-24.69% w.b.) and three metal salt levels (0.05-2.00%) were determined by an open-ended coaxial probe and impedance analyzer. Results indicated that both ε' and ε″ of RB samples increased with increasing temperature and MC. The increase rate was greater at higher temperature and moisture levels than at lower levels, especially at frequencies lower than 300 MHz. Cubic order models were developed to best fit the relationship between DPs of RB samples and temperature/MC at five frequencies with R 2 greater than 0.994. Both ε″ and RF heating rate of RB samples increased significantly with added NaCl (2%), KCl (1%) and Na 6 O 18 P 6 (2%). The obtained data are useful in developing computer models and simulating dielectric heating for RB stabilization and may also provide theoretical basis for synergistic stabilization of RB under combined dielectric heating with metal salts.

Representativeness of direct observations selected using a work-sampling equation.

PubMed

Sharp, Rebecca A; Mudford, Oliver C; Elliffe, Douglas

2015-01-01

Deciding on appropriate sampling to obtain representative samples of behavior is important but not straightforward, because the relative duration of the target behavior may affect its observation in a given sampling interval. Work-sampling methods, which offer a way to adjust the frequency of sampling according to a priori or ongoing estimates of the behavior to achieve a preselected level of representativeness, may provide a solution. Full-week observations of 7 behaviors were conducted for 3 students with autism spectrum disorder and intellectual disabilities. Work-sampling methods were used to select momentary time samples from the full time-of-interest, which produced representative samples. However, work sampling required impractically high numbers of time samples to obtain representative samples. More practical momentary time samples produced less representative samples, particularly for low-duration behaviors. The utility and limits of work-sampling methods for applied behavior analysis are discussed. © Society for the Experimental Analysis of Behavior.

Diversity, Frequency, and Persistence of Escherichia coli O157 Strains from Range Cattle Environments†

PubMed Central

Renter, David G.; Sargeant, Jan M.; Oberst, Richard D.; Samadpour, Mansour

2003-01-01

Genetic diversity, isolation frequency, and persistence were determined for Escherichia coli O157 strains from range cattle production environments. Over the 11-month study, analysis of 9,122 cattle fecal samples, 4,083 water source samples, and 521 wildlife fecal samples resulted in 263 isolates from 107 samples presumptively considered E. coli O157 as determined by culture and latex agglutination. Most isolates (90.1%) were confirmed to be E. coli O157 by PCR detection of intimin and Shiga toxin genes. Pulsed-field gel electrophoresis (PFGE) of XbaI-digested preparations revealed 79 unique patterns (XbaI-PFGE subtypes) from 235 typeable isolates confirmed to be E. coli O157. By analyzing up to three isolates per positive sample, we detected an average of 1.80 XbaI-PFGE subtypes per sample. Most XbaI-PFGE subtypes (54 subtypes) were identified only once, yet the seven most frequently isolated subtypes represented over one-half of the E. coli O157 isolates (124 of 235 isolates). Recurring XbaI-PFGE subtypes were recovered from samples on up to 10 sampling occasions and up to 10 months apart. Seven XbaI-PFGE subtypes were isolated from both cattle feces and water sources, and one of these also was isolated from the feces of a wild opossum (Didelphis sp.). The number of XbaI-PFGE subtypes, the variable frequency and persistence of subtypes, and the presence of identical subtypes in cattle feces, free-flowing water sources, and wildlife feces indicate that the complex molecular epidemiology of E. coli O157 previously described for confined cattle operations is also evident in extensively managed range cattle environments. PMID:12514039

Digital timing: sampling frequency, anti-aliasing filter and signal interpolation filter dependence on timing resolution.

PubMed

Cho, Sanghee; Grazioso, Ron; Zhang, Nan; Aykac, Mehmet; Schmand, Matthias

2011-12-07

The main focus of our study is to investigate how the performance of digital timing methods is affected by sampling rate, anti-aliasing and signal interpolation filters. We used the Nyquist sampling theorem to address some basic questions such as what will be the minimum sampling frequencies? How accurate will the signal interpolation be? How do we validate the timing measurements? The preferred sampling rate would be as low as possible, considering the high cost and power consumption of high-speed analog-to-digital converters. However, when the sampling rate is too low, due to the aliasing effect, some artifacts are produced in the timing resolution estimations; the shape of the timing profile is distorted and the FWHM values of the profile fluctuate as the source location changes. Anti-aliasing filters are required in this case to avoid the artifacts, but the timing is degraded as a result. When the sampling rate is marginally over the Nyquist rate, a proper signal interpolation is important. A sharp roll-off (higher order) filter is required to separate the baseband signal from its replicates to avoid the aliasing, but in return the computation will be higher. We demonstrated the analysis through a digital timing study using fast LSO scintillation crystals as used in time-of-flight PET scanners. From the study, we observed that there is no significant timing resolution degradation down to 1.3 Ghz sampling frequency, and the computation requirement for the signal interpolation is reasonably low. A so-called sliding test is proposed as a validation tool checking constant timing resolution behavior of a given timing pick-off method regardless of the source location change. Lastly, the performance comparison for several digital timing methods is also shown.

Interaction effects between the 5-hydroxy tryptamine transporter-linked polymorphic region (5-HTTLPR) genotype and family conflict on adolescent alcohol use and misuse.

PubMed

Kim, Jueun; Park, Aesoon; Glatt, Stephen J; Eckert, Tanya L; Vanable, Peter A; Scott-Sheldon, Lori A J; Carey, Kate B; Ewart, Craig K; Carey, Michael P

2015-02-01

To investigate whether the effects of family conflict on adolescent drinking differed as a function of 5-hydroxy tryptamine transporter-linked polymorphic region (5-HTTLPR) genotype cross-sectionally and prospectively in two independent samples of adolescents. Path analysis and multi-group analysis of two prospective datasets were conducted. United States and United Kingdom. Sample 1 was 175 adolescents in the United States (mean age = 15 at times 1 and 2 with a 6-month interval); Sample 2 was 4916 adolescents in the United Kingdon (mean age = 12 at time 1 and 15 at time 2). In both samples, demographics, tri-allelic 5-HTTLPR genotype and perceived family conflict were assessed at time 1. Alcohol use (frequency of drinking) and alcohol misuse (frequency of intoxication, frequency of drinking three or more drinks, maximum number of drinks) were assessed at times 1 and 2. A significant gene-environment interaction on alcohol misuse at time 1 was found in both sample 1 (β = 0.57, P = 0.001) and sample 2 (β = 0.19, P = 0.01), indicating that the 5-HTTLPR low-activity allele carriers exposed to higher levels of family conflict were more likely to engage in alcohol misuse than non-carriers. A significant gene-environment interaction effect on change in alcohol misuse over time was found only in sample 1 (β = 0.48, P = 0.04) but not in sample 2. Compared with non-carriers, adolescents carrying the 5-HTTLPR low-activity allele are more susceptible to the effects of family conflict on alcohol misuse. © 2014 Society for the Study of Addiction.

Estimating and comparing microbial diversity in the presence of sequencing errors

PubMed Central

Chiu, Chun-Huo

2016-01-01

Estimating and comparing microbial diversity are statistically challenging due to limited sampling and possible sequencing errors for low-frequency counts, producing spurious singletons. The inflated singleton count seriously affects statistical analysis and inferences about microbial diversity. Previous statistical approaches to tackle the sequencing errors generally require different parametric assumptions about the sampling model or about the functional form of frequency counts. Different parametric assumptions may lead to drastically different diversity estimates. We focus on nonparametric methods which are universally valid for all parametric assumptions and can be used to compare diversity across communities. We develop here a nonparametric estimator of the true singleton count to replace the spurious singleton count in all methods/approaches. Our estimator of the true singleton count is in terms of the frequency counts of doubletons, tripletons and quadrupletons, provided these three frequency counts are reliable. To quantify microbial alpha diversity for an individual community, we adopt the measure of Hill numbers (effective number of taxa) under a nonparametric framework. Hill numbers, parameterized by an order q that determines the measures’ emphasis on rare or common species, include taxa richness (q = 0), Shannon diversity (q = 1, the exponential of Shannon entropy), and Simpson diversity (q = 2, the inverse of Simpson index). A diversity profile which depicts the Hill number as a function of order q conveys all information contained in a taxa abundance distribution. Based on the estimated singleton count and the original non-singleton frequency counts, two statistical approaches (non-asymptotic and asymptotic) are developed to compare microbial diversity for multiple communities. (1) A non-asymptotic approach refers to the comparison of estimated diversities of standardized samples with a common finite sample size or sample completeness. This approach aims to compare diversity estimates for equally-large or equally-complete samples; it is based on the seamless rarefaction and extrapolation sampling curves of Hill numbers, specifically for q = 0, 1 and 2. (2) An asymptotic approach refers to the comparison of the estimated asymptotic diversity profiles. That is, this approach compares the estimated profiles for complete samples or samples whose size tends to be sufficiently large. It is based on statistical estimation of the true Hill number of any order q ≥ 0. In the two approaches, replacing the spurious singleton count by our estimated count, we can greatly remove the positive biases associated with diversity estimates due to spurious singletons and also make fair comparisons across microbial communities, as illustrated in our simulation results and in applying our method to analyze sequencing data from viral metagenomes. PMID:26855872

Frequency of hepatocellular fibrillar inclusions in European flounder (Platichthys flesus) from the Douro River estuary, Portugal.

PubMed

Carrola, João; Fontaínhas-Fernandes, António; Pires, Maria João; Rocha, Eduardo

2014-02-01

Liver lesions in wild fish have been associated with xenobiotic exposure. Facing reports of pollution in the Douro River estuary (north of Portugal), we have been making field surveys using fishes and targeting histopathological biomarkers of exposure and effect. Herein, we intended to better characterize and report the rate of one poorly understood lesion-hepatocellular fibrillar inclusions (HFI)-found in European flounder (Platichthys flesus). With this report, we aimed to establish sound baseline data that could be viewed as a starting point for future biomonitoring, while offering the world's second only pool of field data on such a liver toxicopathic lesion, which could be compared with data available from the UK estuaries. Sampling was done in the Douro River estuary over 1 year. A total of 72 animals were fished with nets, in spring-summer (SS) and autumn-winter (AW) campaigns. Livers were processed for histopathology and both routine and special staining procedures (alcian blue, periodic acid Schiff (PAS), tetrazonium coupling reaction). Immunohistochemistry targeted AE1/AE3 (pan cytokeratins). The severity of the HFI extent was graded using a system with four levels, varying from 0 (absence of HFI) to 3 (high relative density of cells with HFI). Cells (isolated/groups) with HFI appeared in 35 % or more of the fish, in the total samples of each season, and over 40 % in more homogeneous sub-samples. There were no significant differences when comparing samples versus sub-samples or SS versus AW. When merging the data sets from the two seasons, the frequency of fish with HFI was ≈36 % for the total sample and ≈49 % for the sub-sample. The extreme group (biggest and smallest fish) revealed a HFI frequency of only 16 %, which differed significantly from the total and sub-sampled groups. Immunostaining and PAS were negative for the HFI, and alcian blue could, at times, faintly stain the inclusions. These were positive with the tetrazonium reaction. We showed the presence of HFI in European flounder from the Douro River estuary, proving that they are essentially protein in nature, that no seasonal changes existed in the HFI frequency, and that it was rarer in the smallest and biggest fish groups. Within the ranges of weight/size of our total sample, we estimate that the frequency of HFI in the local flounder is ≈35 %. That rate stands as a baseline value for future assessments, namely for biomonitoring purposes targeting correlations with the estuary pollution status.

A system for measuring complex dielectric properties of thin films at submillimeter wavelengths using an open hemispherical cavity and a vector network analyzer

NASA Astrophysics Data System (ADS)

Rahman, Rezwanur; Taylor, P. C.; Scales, John A.

2013-08-01

Quasi-optical (QO) methods of dielectric spectroscopy are well established in the millimeter and submillimeter frequency bands. These methods exploit standing wave structure in the sample produced by a transmitted Gaussian beam to achieve accurate, low-noise measurement of the complex permittivity of the sample [e.g., J. A. Scales and M. Batzle, Appl. Phys. Lett. 88, 062906 (2006);, 10.1063/1.2172403 R. N. Clarke and C. B. Rosenberg, J. Phys. E 15, 9 (1982);, 10.1088/0022-3735/15/1/002 T. M. Hirovnen, P. Vainikainen, A. Lozowski, and A. V. Raisanen, IEEE Trans. Instrum. Meas. 45, 780 (1996)], 10.1109/19.516996. In effect the sample itself becomes a low-Q cavity. On the other hand, for optically thin samples (films of thickness much less than a wavelength) or extremely low loss samples (loss tangents below 10-5) the QO approach tends to break down due to loss of signal. In such a case it is useful to put the sample in a high-Q cavity and measure the perturbation of the cavity modes. Provided that the average mode frequency divided by the shift in mode frequency is less than the Q (quality factor) of the mode, then the perturbation should be resolvable. Cavity perturbation techniques are not new, but there are technological difficulties in working in the millimeter/submillimeter wave region. In this paper we will show applications of cavity perturbation to the dielectric characterization of semi-conductor thin films of the type used in the manufacture of photovoltaics in the 100 and 350 GHz range. We measured the complex optical constants of hot-wire chemical deposition grown 1-μm thick amorphous silicon (a-Si:H) film on borosilicate glass substrate. The real part of the refractive index and dielectric constant of the glass-substrate varies from frequency-independent to linearly frequency-dependent. We also see power-law behavior of the frequency-dependent optical conductivity from 316 GHz (9.48 cm-1) down to 104 GHz (3.12 cm-1).

Characterization of soil behavior using electromagnetic wave-based technique

NASA Astrophysics Data System (ADS)

Dong, Xiaobo

A 2.2 mm open-ended coaxial probe is selected to explore the broadband measurement of complex permittivity ranging from kHz up to GHz. The measurements are conducted in three different frequency ranges, i.e., high frequency (HF, 500 MHz ˜ 20 GHz), medium frequency (MF, 10 MHz ˜ 1 GHz), and low frequency (LF, 1 kHz ˜ 15 MHz), in view of pertinent aperture admittance models, feasible measurement principles, and required calibrations for system biases. These considerations are discussed and described in turn from the high frequency measurements to low frequency tests. Verification of the associated measurement techniques in the three operating frequency regimes is provided by experiments on pure ethanol and methanol liquids as well as on NaCl solutions of different concentrations. These testing techniques are also applied to measure the broadband dielectric spectrum of kaolinite slurry; simple analyses focusing on subtracting the influence of DC conductivity and multiple relaxations are presented. A complex permittivity spectrum from 1 kHz to 3 GHz is measured in kaolinite sediment of different structures using the slim-form open-ended coaxial probe. The sediment structure is manipulated by changing the pore-fluid pH. When the pH is below the isoelectrical point of the edge surface, IEPedge, the structure of face-to-edge (EF) flocculation is promoted in voluminous sediment (Group A samples). A higher dielectric constant due to bulk water polarization is measured because of the higher water content. As the pH is increased to greater than IEP edge, dense sediment with face-to-face (FF) aggregation is produced (Group B samples) and a lower dielectric constant is obtained. In bound water and spatial polarization, higher relaxation strength and longer relaxation time are observed in the Group B samples, which can be attributed to more negatively charged surfaces and denser packing. Fluid conductivity dominates the global conductivity of the sediment in the Group A samples so that the beta value, i.e., the ratio between the conductivities of the sediment and the fluid, is smaller than 1. The beta value is greater than 1 in the Group B samples owing to an overcompensation of surface conduction. Sedimentation behavior of two kaolinite samples with distinct fabric associations is characterized using mechanical and electromagnetic wave-based techniques. The two different fabric formations, the edge-to-face (EF) flocculated structure (i.e., sample A) and the dispersed and deflocculated structure (i.e., sample B), were regulated by changing the pH of the pore fluid and are produced. The anisotropy of shear wave velocity and DC conductivity was not observed in the sediment of sample A because of EF isotropic fabric associations but it was detected in sample B as a result of face-to-face (FF) aggregation. An open card-house structure of the sample A sediment results in a higher relaxation strength of the bulk water, Deltakappaw owing to a higher water content; the smaller Deltakappaw measured in the sample B sediment indicates denser packing. In both samples, sediment consolidation gives rise to a decrease in the bulk-water relaxation strength but an increase in the bound-water relaxation strength owing to increasing particle content. In response to sediment consolidation, the sediment conductivity of sample A continuously decreases because of the reduced contribution from the fluid conductivity. In sample B, the surface conduction via the overlapped double layer overcompensates such a decreased contribution so that the sediment conductivity increases with increasing particle content. The slim-form open-ended coaxial probe is also used to conduct a local dielectric measurement. The measured results, i.e. dielectric relaxation strength of bulk water, Deltakappaw, and the DC conductivity of the saturated sample, sigmamix, are jointly used to characterize the spatial variability of different specimens including glass beads, sand and mica samples, and kaolinte sediments with two different fabric associations. The pore distribution along the sample depth can be reflected from the measured Deltakappaw, and the local porosity can be estimated based on the mixing rules. The directional feature of the interconnected pores is captured in the totruosity which is derived from the measured sigmamix. In the kaolinite sediments, the ratio between the sediment and the pore-fluid conductivity not only reveals the spatial variability of the sediment packing but also the relative contribution of the fluid conductivity and surface conduction to the global sediment conductivity.

A three-dimensional finite element model of near-field scanning microwave microscopy

NASA Astrophysics Data System (ADS)

Balusek, Curtis; Friedman, Barry; Luna, Darwin; Oetiker, Brian; Babajanyan, Arsen; Lee, Kiejin

2012-10-01

A three-dimensional finite element model of an experimental near-field scanning microwave microscope (NSMM) has been developed and compared to experiment on non conducting samples. The microwave reflection coefficient S11 is calculated as a function of frequency with no adjustable parameters. There is qualitative agreement with experiment in that the resonant frequency can show a sizable increase with sample dielectric constant; a result that is not obtained with a two-dimensional model. The most realistic model shows a semi-quantitative agreement with experiment. The effect of different sample thicknesses and varying tip sample distances is investigated numerically and shown to effect NSMM performance in a way consistent with experiment. Visualization of the electric field indicates that the field is primarily determined by the shape of the coupling hooks.

The Impact of Sampling Schemes on the Site Frequency Spectrum in Nonequilibrium Subdivided Populations

PubMed Central

Städler, Thomas; Haubold, Bernhard; Merino, Carlos; Stephan, Wolfgang; Pfaffelhuber, Peter

2009-01-01

Using coalescent simulations, we study the impact of three different sampling schemes on patterns of neutral diversity in structured populations. Specifically, we are interested in two summary statistics based on the site frequency spectrum as a function of migration rate, demographic history of the entire substructured population (including timing and magnitude of specieswide expansions), and the sampling scheme. Using simulations implementing both finite-island and two-dimensional stepping-stone spatial structure, we demonstrate strong effects of the sampling scheme on Tajima's D (DT) and Fu and Li's D (DFL) statistics, particularly under specieswide (range) expansions. Pooled samples yield average DT and DFL values that are generally intermediate between those of local and scattered samples. Local samples (and to a lesser extent, pooled samples) are influenced by local, rapid coalescence events in the underlying coalescent process. These processes result in lower proportions of external branch lengths and hence lower proportions of singletons, explaining our finding that the sampling scheme affects DFL more than it does DT. Under specieswide expansion scenarios, these effects of spatial sampling may persist up to very high levels of gene flow (Nm > 25), implying that local samples cannot be regarded as being drawn from a panmictic population. Importantly, many data sets on humans, Drosophila, and plants contain signatures of specieswide expansions and effects of sampling scheme that are predicted by our simulation results. This suggests that validating the assumption of panmixia is crucial if robust demographic inferences are to be made from local or pooled samples. However, future studies should consider adopting a framework that explicitly accounts for the genealogical effects of population subdivision and empirical sampling schemes. PMID:19237689

Dynamic microparticle manipulation with an electroosmotic flow gradient in low-frequency alternating current dielectrophoresis.

PubMed

Gencoglu, Aytug; Olney, David; LaLonde, Alexandra; Koppula, Karuna S; Lapizco-Encinas, Blanca H

2014-02-01

In this study, the potential of low-frequency AC insulator-based DEP (iDEP) was explored for the separation of polystyrene microparticles and yeast cells. An EOF gradient was generated by employing an asymmetrical, 20 Hz AC electrical signal in an iDEP device consisting of a microchannel with diamond-shaped insulating posts. Two types of samples were analyzed, the first sample contained three types of polystyrene particles with different diameters (0.5, 1.0, and 2.0 μm) and the second sample contained two types of polystyrene particles (1.0 and 2 μm) and yeast cells (6.3 μm). This particular scheme uses a tapered AC signal that allows for all particles to be trapped and concentrated at the insulating post array, as the signal becomes asymmetrical (more positive), particles are selectively released. The smallest particles in each sample were released first, since they require greater dielectrophoretic forces to remain trapped. The largest particles in each sample were released last, when the applied signal became cyclical. A dielectropherogram, which is analogous to a chromatogram, was obtained for each sample, demonstrating successful separation of the particles by showing "peaks" of the released particles. These separations were achieved at lower applied potentials than those reported in previous studies that used solely direct current electrical voltages. Additionally, mathematical modeling with COMSOL Multiphysics was carried out to estimate the magnitude of the dielectrophoretic and EOF forces acting on the particles considering the low-frequency, asymmetrical AC signal used in the experiments. The results demonstrated the potential of low-frequency AC-iDEP systems for handling and separating complex mixtures of microparticles and biological cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Research on Time-frequency Characteristics of Magneto-acoustic Signal of Different Thickness Medium Based on Wave Summing Method].

PubMed

Zhang, Shunqi; Yin, Tao; Ma, Ren; Liu, Zhipeng

2015-08-01

Functional imaging method of biological electrical characteristics based on magneto-acoustic effect gives valuable information of tissue in early tumor diagnosis, therein time and frequency characteristics analysis of magneto-acoustic signal is important in image reconstruction. This paper proposes wave summing method based on Green function solution for acoustic source of magneto-acoustic effect. Simulations and analysis under quasi 1D transmission condition are carried out to time and frequency characteristics of magneto-acoustic signal of models with different thickness. Simulation results of magneto-acoustic signal were verified through experiments. Results of the simulation with different thickness showed that time-frequency characteristics of magneto-acoustic signal reflected thickness of sample. Thin sample, which is less than one wavelength of pulse, and thick sample, which is larger than one wavelength, showed different summed waveform and frequency characteristics, due to difference of summing thickness. Experimental results verified theoretical analysis and simulation results. This research has laid a foundation for acoustic source and conductivity reconstruction to the medium with different thickness in magneto-acoustic imaging.

Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

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

Morawski, Ireneusz; Institute of Experimental Physics, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław; Spiegelberg, Richard

A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. Themore » high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations.« less

Regional HLA Differences in Poland and Their Effect on Stem Cell Donor Registry Planning

PubMed Central

Schmidt, Alexander H.; Solloch, Ute V.; Pingel, Julia; Sauter, Jürgen; Böhme, Irina; Cereb, Nezih; Dubicka, Kinga; Schumacher, Stephan; Wachowiak, Jacek; Ehninger, Gerhard

2013-01-01

Regional HLA frequency differences are of potential relevance for the optimization of stem cell donor recruitment. We analyzed a very large sample (n = 123,749) of registered Polish stem cell donors. Donor figures by 1-digit postal code regions ranged from n = 5,243 (region 9) to n = 19,661 (region 8). Simulations based on region-specific haplotype frequencies showed that donor recruitment in regions 0, 2, 3 and 4 (mainly located in the south-eastern part of Poland) resulted in an above-average increase of matching probabilities for Polish patients. Regions 1, 7, 8, 9 (mainly located in the northern part of Poland) showed an opposite behavior. However, HLA frequency differences between regions were generally small. A strong indication for regionally focused donor recruitment efforts can, therefore, not be derived from our analyses. Results of haplotype frequency estimations showed sample size effects even for sizes between n≈5,000 and n≈20,000. This observation deserves further attention as most published haplotype frequency estimations are based on much smaller samples. PMID:24069237

Probing the Jet Turnover Frequency Dependence on Mass and Mass Accretion Rate

NASA Astrophysics Data System (ADS)

Hammerstein, Erica; Gültekin, Kayhan; King, Ashley

2018-01-01

We have examined a sample of 15 sub-Eddington supermassive black holes (SMBHs) in a variety of galaxy classifications to further understand the proposed fundamental plane of black hole activity and scaling relations between black hole masses and their radio and X-ray luminosities. This plane describes black holes from stellar-mass to supermassive. The physics probed by these sub-Eddington systems is thought to be a radiatively inefficient, jet-dominated accretion flow. By studying black holes in this regime, we can learn important information on the disk-jet connection for accreting black holes.A key factor in studying the fundamental plane is the turnover frequency — the frequency at which emission transitions from optically thick at lower frequencies to optically thin at higher frequencies. This turnover point can be measured by observing the source in both radio and X-ray. Our project aims to test the dependence of the turnover frequency on mass and mass accretion rate.Radio observations of the sample were obtained using the Karl G. Jansky Very Large Array (VLA) in the range of 5-40 GHz across four different frequency bands in A configuration to give the highest spatial resolution to focus on the core emission. Our carefully chosen sample of SMBHs with dynamically measured masses consists of two sub-samples: those with approximately constant mass accretion rate (LX/LEdd ~ 10‑7) and those with approximately constant mass (MBH ~ 108 Msun). X-ray data were obtained from archival Chandra observations. To find the turnover frequency, we used Markov Chain Monte Carlo methods to fit two power laws to the radio data and the archival X-ray data. The intersection of the radio and X-ray fits is the turnover frequency.We present the results for both subsamples of SMBHs and their relationship between the turnover frequency and X-ray luminosity, which we take to scale with mass accretion rate, and jet power derived from both radio and X-ray properties.

A New Proof of the Expected Frequency Spectrum under the Standard Neutral Model.

PubMed

Hudson, Richard R

2015-01-01

The sample frequency spectrum is an informative and frequently employed approach for summarizing DNA variation data. Under the standard neutral model the expectation of the sample frequency spectrum has been derived by at least two distinct approaches. One relies on using results from diffusion approximations to the Wright-Fisher Model. The other is based on Pólya urn models that correspond to the standard coalescent model. A new proof of the expected frequency spectrum is presented here. It is a proof by induction and does not require diffusion results and does not require the somewhat complex sums and combinatorics of the derivations based on urn models.

Thermal Images of Seeds Obtained at Different Depths by Photoacoustic Microscopy (PAM)

NASA Astrophysics Data System (ADS)

Domínguez-Pacheco, A.; Hernández-Aguilar, C.; Cruz-Orea, A.

2015-06-01

The objective of the present study was to obtain thermal images of a broccoli seed ( Brassica oleracea) by photoacoustic microscopy, at different modulation frequencies of the incident light beam ((0.5, 1, 5, and 20) Hz). The thermal images obtained in the amplitude of the photoacoustic signal vary with each applied frequency. In the lowest light frequency modulation, there is greater thermal wave penetration in the sample. Likewise, the photoacoustic signal is modified according to the structural characteristics of the sample and the modulation frequency of the incident light. Different structural components could be seen by photothermal techniques, as shown in the present study.

An extension of command shaping methods for controlling residual vibration using frequency sampling

NASA Technical Reports Server (NTRS)

Singer, Neil C.; Seering, Warren P.

1992-01-01

The authors present an extension to the impulse shaping technique for commanding machines to move with reduced residual vibration. The extension, called frequency sampling, is a method for generating constraints that are used to obtain shaping sequences which minimize residual vibration in systems such as robots whose resonant frequencies change during motion. The authors present a review of impulse shaping methods, a development of the proposed extension, and a comparison of results of tests conducted on a simple model of the space shuttle robot arm. Frequency shaping provides a method for minimizing the impulse sequence duration required to give the desired insensitivity.

RFI Risk Reduction Activities Using New Goddard Digital Radiometry Capabilities

NASA Technical Reports Server (NTRS)

Bradley, Damon; Kim, Ed; Young, Peter; Miles, Lynn; Wong, Mark; Morris, Joel

2012-01-01

The Goddard Radio-Frequency Explorer (GREX) is the latest fast-sampling radiometer digital back-end processor that will be used for radiometry and radio-frequency interference (RFI) surveying at Goddard Space Flight Center. The system is compact and deployable, with a mass of about 40 kilograms. It is intended to be flown on aircraft. GREX is compatible with almost any aircraft, including P-3, twin otter, C-23, C-130, G3, and G5 types. At a minimum, the system can function as a clone of the Soil Moisture Active Passive (SMAP) ground-based development unit [1], or can be a completely independent system that is interfaced to any radiometer, provided that frequency shifting to GREX's intermediate frequency is performed prior to sampling. If the radiometer RF is less than 200MHz, then the band can be sampled and acquired directly by the system. A key feature of GREX is its ability to simultaneously sample two polarization channels simultaneously at up to 400MSPS, 14-bit resolution each. The sampled signals can be recorded continuously to a 23 TB solid-state RAID storage array. Data captures can be analyzed offline using the supercomputing facilities at Goddard Space Flight Center. In addition, various Field Programmable Gate Array (FPGA) - amenable radiometer signal processing and RFI detection algorithms can be implemented directly on the GREX system because it includes a high-capacity Xilinx Virtex-5 FPGA prototyping system that is user customizable.

Quantitative optical frequency domain imaging assessment of in-stent structures in patients with ST-segment elevation myocardial infarction: impact of imaging sampling rate.

PubMed

Muramatsu, Takashi; García-García, Hector M; Lee, Il Soo; Bruining, Nico; Onuma, Yoshinobu; Serruys, Patrick W

2012-01-01

The impact of the sampling rate (SR) of optical frequency domain imaging (OFDI) on quantitative assessment of in-stent structures (ISS) such as plaque prolapse and thrombus remains unexplored. OFDI after stenting was performed in ST-segment elevation myocardial infarction (STEMI) patients using a TERUMO OFDI system (Terumo Europe, Leuven, Belgium) with 160 frames/s and pullback speed of 20 mm/s. A total of 126 stented segments were analyzed. ISS were classified as either attached or non-attached to stent area boundaries. The volume, mean area and largest area of ISS were assessed according to 4 frequencies of SR, corresponding to distances between the analyzed frames of 0.125, 0.25, 0.50 and 1.0 mm. ISS volume was calculated by integrating cross-sectional ISS areas multiplied by each sampling distance using the disk summation method. The volume and mean area of ISS became significantly larger, while the largest area became significantly smaller as sampling distance became larger (1.11 mm(2) for 0.125 mm vs. 1.00 mm(2) for 1.0 mm, P for trend=0.036). In addition, variance of difference was positively associated with increasing width of sampling distance. Quantification of ISS is significantly influenced by the applied frequency of SR. This should be taken into account when designing future OFDI studies in which quantitative assessment of ISS is critical for the evaluation of STEMI patients.

Compressive power spectrum sensing for vibration-based output-only system identification of structural systems in the presence of noise

NASA Astrophysics Data System (ADS)

Tau Siesakul, Bamrung; Gkoktsi, Kyriaki; Giaralis, Agathoklis

2015-05-01

Motivated by the need to reduce monetary and energy consumption costs of wireless sensor networks in undertaking output-only/operational modal analysis of engineering structures, this paper considers a multi-coset analog-toinformation converter for structural system identification from acceleration response signals of white noise excited linear damped structures sampled at sub-Nyquist rates. The underlying natural frequencies, peak gains in the frequency domain, and critical damping ratios of the vibrating structures are estimated directly from the sub-Nyquist measurements and, therefore, the computationally demanding signal reconstruction step is by-passed. This is accomplished by first employing a power spectrum blind sampling (PSBS) technique for multi-band wide sense stationary stochastic processes in conjunction with deterministic non-uniform multi-coset sampling patterns derived from solving a weighted least square optimization problem. Next, modal properties are derived by the standard frequency domain peak picking algorithm. Special attention is focused on assessing the potential of the adopted PSBS technique, which poses no sparsity requirements to the sensed signals, to derive accurate estimates of modal structural system properties from noisy sub- Nyquist measurements. To this aim, sub-Nyquist sampled acceleration response signals corrupted by various levels of additive white noise pertaining to a benchmark space truss structure with closely spaced natural frequencies are obtained within an efficient Monte Carlo simulation-based framework. Accurate estimates of natural frequencies and reasonable estimates of local peak spectral ordinates and critical damping ratios are derived from measurements sampled at about 70% below the Nyquist rate and for SNR as low as 0db demonstrating that the adopted approach enjoys noise immunity.

Correlation between k-space sampling pattern and MTF in compressed sensing MRSI.

PubMed

Heikal, A A; Wachowicz, K; Fallone, B G

2016-10-01

To investigate the relationship between the k-space sampling patterns used for compressed sensing MR spectroscopic imaging (CS-MRSI) and the modulation transfer function (MTF) of the metabolite maps. This relationship may allow the desired frequency content of the metabolite maps to be quantitatively tailored when designing an undersampling pattern. Simulations of a phantom were used to calculate the MTF of Nyquist sampled (NS) 32 × 32 MRSI, and four-times undersampled CS-MRSI reconstructions. The dependence of the CS-MTF on the k-space sampling pattern was evaluated for three sets of k-space sampling patterns generated using different probability distribution functions (PDFs). CS-MTFs were also evaluated for three more sets of patterns generated using a modified algorithm where the sampling ratios are constrained to adhere to PDFs. Strong visual correlation as well as high R 2 was found between the MTF of CS-MRSI and the product of the frequency-dependant sampling ratio and the NS 32 × 32 MTF. Also, PDF-constrained sampling patterns led to higher reproducibility of the CS-MTF, and stronger correlations to the above-mentioned product. The relationship established in this work provides the user with a theoretical solution for the MTF of CS MRSI that is both predictable and customizable to the user's needs.

Structural elucidation and magnetic behavior evaluation of Cu-Cr doped BaCo-X hexagonal ferrites

NASA Astrophysics Data System (ADS)

Azhar Khan, Muhammad; Hussain, Farhat; Rashid, Muhammad; Mahmood, Asif; Ramay, Shahid M.; Majeed, Abdul

2018-04-01

Ba2-xCuxCo2CryFe28-yO46 (x = 0.0, 0.1, 0.2, 0.3, 0.4, y = 0.0, 0.2, 0.4, 0.6, 0.8) X-type hexagonal ferrites were synthesized via micro-emulsion route. The techniques which were applied to characterize the prepared samples are as follows: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Dielectric measurements and vibrating sample magnetometer (VSM). The structural parameters i.e. lattice constant (a, c), cell volume (V), X-ray density, bulk density and crystallite size of all the prepared samples were obtained using XRD analysis. The lattice parameters 'a' and 'c' increase from 5.875 Å to 5.934 Å and 83.367 Å to 83.990 Å respectively. The crystallite size of investigated samples lies in the range of 28-32 nm. The magnetic properties of all samples have been calculated by vibrating sample magnetometer (VSM) analysis. The increase in coercivity (Hc) was observed with the increase of doping contents. It was observed that the coercivity (Hc) of all prepared samples is inversely related to the crystalline size which reflects that all materials are super-paramagnetic. The dielectric parameters i.e. dielectric constant, dielectric loss, tangent loss etc were obtained in the frequency range of 1 MHz-3 GHz and followed the Maxwell-Wagner's model. The significant variation the dielectric parameters are observed with increasing frequency. The maximum Q value is obtained at ∼2 GHz due to which these materials are used for high frequency multilayer chip inductors.

Review of image processing fundamentals

NASA Technical Reports Server (NTRS)

Billingsley, F. C.

1985-01-01

Image processing through convolution, transform coding, spatial frequency alterations, sampling, and interpolation are considered. It is postulated that convolution in one domain (real or frequency) is equivalent to multiplication in the other (frequency or real), and that the relative amplitudes of the Fourier components must be retained to reproduce any waveshape. It is suggested that all digital systems may be considered equivalent, with a frequency content approximately at the Nyquist limit, and with a Gaussian frequency response. An optimized cubic version of the interpolation continuum image is derived as a set of cubic spines. Pixel replication has been employed to enlarge the visable area of digital samples, however, suitable elimination of the extraneous high frequencies involved in the visable edges, by defocusing, is necessary to allow the underlying object represented by the data values to be seen.

Size optimization for complex permeability measurement of magnetic thin films using a short-circuited microstrip line up to 30 GHz

NASA Astrophysics Data System (ADS)

Takeda, Shigeru; Naoe, Masayuki

2018-03-01

High-frequency permeability spectra of magnetic films were measured over a wideband frequency range of 0.1-30 GHz using a shielded and short-circuited microstrip line jig. In this measurement, spurious resonances had to be suppressed up to the highest frequency. To suppress these resonances, characteristic impedance of the microstrip line should approach 50 Ω at the junction between connector and microstrip line. The main factors dominating these resonances were structures of the jig and the sample. The dimensions were optimized in various experiments, and results demonstrated that the frequency could be raised to at least 20 GHz. For the transverse electromagnetic mode to transmit stably along the microstrip line, the preferred sample was rectangular, with the shorter side parallel to the line and the longer side perpendicular to it, and characteristic impedance strongly depended on the signal line width of the jig. However, too small a jig and sample led to a lower S/N ratio.

Dielectric Relaxation In Complex Perovskite Sm(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}

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

Kumar, Nishant; Prasad, S.; Sinha, T. P.

2011-11-22

The complex perovskite oxide Samarium nickel titenate, Sm(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}(SNT) is synthesized by a solid-state reaction technique. The X-ray diffraction of the sample at room temperature shows a monoclinic phase. The scanning micrograph of the sample shows the average grain size{approx_equal}0.6{mu}m The field dependence of dielectric response and the loss tangent of the sample are measured in a frequency range from 100Hz to 1MHz and in a temperature range from 313 K to 673 K. An analysis of the real and imaginary parts of the dielectric permittivity with frequency is performed, assuming a distribution of relaxation times as confirmedmore » by Cole-Cole plots. The frequency dependent electrical data are analyzed in the framework of conductivity formalism. The frequency dependent conductivity data are fitted to the universal power law. All these formalisms provided for qualitative similarities in the relaxation times.« less

Nanoscale Subsurface Imaging of Nanocomposites via Resonant Difference-Frequency Atomic Force Ultrasonic Microscopy

NASA Technical Reports Server (NTRS)

Cantrell, Sean A.; Cantrell, John H.; Lillehei, Peter T.

2007-01-01

A scanning probe microscope methodology, called resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), has been developed. The method employs an ultrasonic wave launched from the bottom of a sample while the cantilever of an atomic force microscope engages the sample top surface. The cantilever is driven at a frequency differing from the ultrasonic frequency by one of the contact resonance frequencies of the cantilever. The nonlinear mixing of the oscillating cantilever and the ultrasonic wave at the sample surface generates difference-frequency oscillations at the cantilever contact resonance. The resonance-enhanced difference-frequency signals are used to create amplitude and phase-generated images of nanoscale near-surface and subsurface features. RDF-AFUM phase images of LaRC-CP2 polyimide polymer containing embedded nanostructures are presented. A RDF-AFUM micrograph of a 12.7 micrometer thick film of LaRC-CP2 containing a monolayer of gold nanoparticles embedded 7 micrometers below the specimen surface reveals the occurrence of contiguous amorphous and crystalline phases within the bulk of the polymer and a preferential growth of the crystalline phase in the vicinity of the gold nanoparticles. A RDF-AFUM micrograph of LaRC-CP2 film containing randomly dispersed carbon nanotubes reveals the growth of an interphase region at certain nanotube-polymer interfaces.

Contact resonance atomic force microscopy imaging in air and water using photothermal excitation.

PubMed

Kocun, Marta; Labuda, Aleksander; Gannepalli, Anil; Proksch, Roger

2015-08-01

Contact Resonance Force Microscopy (CR-FM) is a leading atomic force microscopy technique for measuring viscoelastic nano-mechanical properties. Conventional piezo-excited CR-FM measurements have been limited to imaging in air, since the "forest of peaks" frequency response associated with acoustic excitation methods effectively masks the true cantilever resonance. Using photothermal excitation results in clean contact, resonance spectra that closely match the ideal frequency response of the cantilever, allowing unambiguous and simple resonance frequency and quality factor measurements in air and liquids alike. This extends the capabilities of CR-FM to biologically relevant and other soft samples in liquid environments. We demonstrate CR-FM in air and water on both stiff silicon/titanium samples and softer polystyrene-polyethylene-polypropylene polymer samples with the quantitative moduli having very good agreement between expected and measured values.

Fiber optics frequency comb enabled linear optical sampling with operation wavelength range extension.

PubMed

Liao, Ruolin; Wu, Zhichao; Fu, Songnian; Zhu, Shengnan; Yu, Zhe; Tang, Ming; Liu, Deming

2018-02-01

Although the linear optical sampling (LOS) technique is powerful enough to characterize various advanced modulation formats with high symbol rates, the central wavelength of a pulsed local oscillator (LO) needs to be carefully set according to that of the signal under test, due to the coherent mixing operation. Here, we experimentally demonstrate wideband LOS enabled by a fiber optics frequency comb (FOFC). Meanwhile, when the broadband FOFC acts as the pulsed LO, we propose a scheme to mitigate the enhanced sampling error arising in the non-ideal response of a balanced photodetector. Finally, precise characterizations of arbitrary 128 Gbps PDM-QPSK wavelength channels from 1550 to 1570 nm are successfully achieved, when a 101.3 MHz frequency spaced comb with a 3 dB spectral power ripple of 20 nm is used.

Sampling to assess species diversity of herbaceous layer vegetation in Allegheny hardwood forests

Treesearch

Todd E. Ristau; Stephen B. Horsley; Larry H. McCormick

2001-01-01

The optimum frequency and time of sampling required to generate comprehensive diversity indices of herbaceous species in Allegheny hardwood forests was studied. Four 8-ha sites on the Allegheny National Forest were sampled monthly from May to August in 1992 and 1993 for herbaceous layer species composition and percent cover.

STATISTICAL DISTRIBUTIONS OF PARTICULATE MATTER AND THE ERROR ASSOCIATED WITH SAMPLING FREQUENCY. (R828678C010)

EPA Science Inventory

The distribution of particulate matter (PM) concentrations has an impact on human health effects and the setting of PM regulations. Since PM is commonly sampled on less than daily schedules, the magnitude of sampling errors needs to be determined. Daily PM data from Spokane, W...

Measured acoustic properties of variable and low density bulk absorbers

NASA Technical Reports Server (NTRS)

Dahl, M. D.; Rice, E. J.

1985-01-01

Experimental data were taken to determine the acoustic absorbing properties of uniform low density and layered variable density samples using a bulk absober with a perforated plate facing to hold the material in place. In the layered variable density case, the bulk absorber was packed such that the lowest density layer began at the surface of the sample and progressed to higher density layers deeper inside. The samples were placed in a rectangular duct and measurements were taken using the two microphone method. The data were used to calculate specific acoustic impedances and normal incidence absorption coefficients. Results showed that for uniform density samples the absorption coefficient at low frequencies decreased with increasing density and resonances occurred in the absorption coefficient curve at lower densities. These results were confirmed by a model for uniform density bulk absorbers. Results from layered variable density samples showed that low frequency absorption was the highest when the lowest density possible was packed in the first layer near the exposed surface. The layers of increasing density within the sample had the effect of damping the resonances.

A survey of organochlorine pesticide residues in cheese samples from three Mexican regions.

PubMed

Albert, L A; Alpuche, L; Bárcenas, C; Rendón, J

1990-01-01

Organochlorine pesticide residues were determined in cheese samples from three Mexican regions. All samples were found to be contaminated by these residues: p,p'-DDE was present in 100% of the samples. Other pesticides found with high frequencies were HCB, three of the BHC isomers, as well as heptachlor and its epoxide. Also found, although less frequently, were residues of p,p'-DDD, p,p'-DDT, aldrin, dieldrin and endrin. Samples from the region known as Comarca Lagunera had the highest number of pesticides per sample. The highest concentrations of residues were found in cheese samples from the Soconusco and the Comarca Lagunera regions.

Evaluation of Two Highly-Multiplexed Custom Panels for Massively Parallel Semiconductor Sequencing on Paraffin DNA

PubMed Central

Kotoula, Vassiliki; Lyberopoulou, Aggeliki; Papadopoulou, Kyriaki; Charalambous, Elpida; Alexopoulou, Zoi; Gakou, Chryssa; Lakis, Sotiris; Tsolaki, Eleftheria; Lilakos, Konstantinos; Fountzilas, George

2015-01-01

Background—Aim Massively parallel sequencing (MPS) holds promise for expanding cancer translational research and diagnostics. As yet, it has been applied on paraffin DNA (FFPE) with commercially available highly multiplexed gene panels (100s of DNA targets), while custom panels of low multiplexing are used for re-sequencing. Here, we evaluated the performance of two highly multiplexed custom panels on FFPE DNA. Methods Two custom multiplex amplification panels (B, 373 amplicons; T, 286 amplicons) were coupled with semiconductor sequencing on DNA samples from FFPE breast tumors and matched peripheral blood samples (n samples: 316; n libraries: 332). The two panels shared 37% DNA targets (common or shifted amplicons). Panel performance was evaluated in paired sample groups and quartets of libraries, where possible. Results Amplicon read ratios yielded similar patterns per gene with the same panel in FFPE and blood samples; however, performance of common amplicons differed between panels (p<0.001). FFPE genotypes were compared for 1267 coding and non-coding variant replicates, 999 out of which (78.8%) were concordant in different paired sample combinations. Variant frequency was highly reproducible (Spearman’s rho 0.959). Repeatedly discordant variants were of high coverage / low frequency (p<0.001). Genotype concordance was (a) high, for intra-run duplicates with the same panel (mean±SD: 97.2±4.7, 95%CI: 94.8–99.7, p<0.001); (b) modest, when the same DNA was analyzed with different panels (mean±SD: 81.1±20.3, 95%CI: 66.1–95.1, p = 0.004); and (c) low, when different DNA samples from the same tumor were compared with the same panel (mean±SD: 59.9±24.0; 95%CI: 43.3–76.5; p = 0.282). Low coverage / low frequency variants were validated with Sanger sequencing even in samples with unfavourable DNA quality. Conclusions Custom MPS may yield novel information on genomic alterations, provided that data evaluation is adjusted to tumor tissue FFPE DNA. To this scope, eligibility of all amplicons along with variant coverage and frequency need to be assessed. PMID:26039550

Application of a Terahertz Multi-Frequency Radiation Source Based on Quantum-Cascade Lasers for Identification of Substances Basing on the Amplitude-Spectral Analysis of the Scattered Field

NASA Astrophysics Data System (ADS)

Aksenov, V. N.; Angeluts, A. A.; Balakin, A. V.; Maksimov, E. M.; Ozheredov, I. A.; Shkurinov, A. P.

2018-05-01

We demonstrate the possibility of using a multi-frequency terahertz source to identify substances basing on the analysis of relative amplitudes of the terahertz waves scattered by the object. The results of studying experimentally the scattering of quasi-monochromatic radiation generated by a two-frequency terahertz quantum-cascade laser by the surface of the samples containing inclusions of absorbing substances are presented. It is shown that the spectral features of absorption of these substances within the terahertz frequency range manifest themselves in variations of the amplitudes of the waves at frequencies of 3.0 and 3.7 THz, which are scattered by the samples under consideration.

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

Yashchuk, Valeriy V; Conley, Raymond; Anderson, Erik H.

We discuss the results of SEM and TEM measurements with the BPRML test samples fabricated from a BPRML (WSi2/Si with fundamental layer thickness of 3 nm) with a Dual Beam FIB (focused ion beam)/SEM technique. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize x-raymore » microscopes. Corresponding work with x-ray microscopes is in progress.« less

High-field dynamic nuclear polarization in aqueous solutions.

PubMed

Prandolini, M J; Denysenkov, V P; Gafurov, M; Endeward, B; Prisner, T F

2009-05-06

Unexpected high DNP enhancements of more than 10 have been achieved in liquid water samples at room temperature and magnetic fields of 9.2 T (corresponding to 400 MHz (1)H NMR frequency and 260 GHz EPR frequency). The liquid samples were polarized in situ using a double-resonance structure, which allows simultaneous excitation of NMR and EPR transitions and achieves significant DNP enhancements at very low incident microwave power of only 45 mW. These results demonstrate the first important step toward the application of DNP to high-resolution NMR, increasing the sensitivity on biomolecules with small sample volumes and at physiologically low concentrations.

Terahertz scattering by two phased media with optically soft scatterers

NASA Astrophysics Data System (ADS)

Kaushik, Mayank; Ng, Brian W.-H.; Fischer, Bernd M.; Abbott, Derek

2012-12-01

Frequency dependent absorption by materials at distinct frequencies in the THz range is commonly used as spectral-fingerprints for identification and classification. For transmission measurements, the substance under study is often mixed with a transparent host material. Refractive index variations arising from the presence of impurities and inconsistencies in the sample's internal structure often cause the incident radiation to scatter. This can significantly distort the measured spectral-fingerprints. In this letter, we present a numerical approach to allay the scattering contribution in THz-TDS measurements, provided the sample's refractive index is known, and reveal the true absorption spectra for a given sample.

Gambling frequency and symptoms of attention-deficit hyperactivity disorder in relation to problem gambling among Swedish adolescents: a population-based study.

PubMed

Hellström, Charlotta; Wagner, Philippe; Nilsson, Kent W; Leppert, Jerzy; Åslund, Cecilia

2017-06-01

To investigate the associations between gambling frequency, attention-deficit hyperactivity disorder (ADHD) symptoms, and problem gambling among adolescent boys and girls. One hypothesis was that adolescents with increased ADHD symptoms have a higher frequency of gambling compared to adolescents with fewer ADHD symptoms. A population-based sample of adolescents (aged 15-18 years) completed a questionnaire on demographics, gambling habits, ADHD symptoms, and problematic gambling; 1412 adolescents (from 4440 sampled) with gambling experience were included in the final sample. A zero-inflated negative binomial regression analysis revealed that increased ADHD symptoms, higher gambling frequency, and higher age were associated with lower odds for being non-susceptible to gambling problems. Moreover, gambling frequency interacted with ADHD symptoms in predicting probability of being non-susceptible to gambling problems. However, when analysing those already susceptible to problem gambling, ADHD symptoms did not modify the effect of gambling frequency on the expected magnitude of gambling problems. In susceptible individuals, problem gambling increased with both increased ADHD symptoms and increased gambling frequency, but the level of problems due to gambling frequency did not change depending on the ADHD symptom level. There was an interaction effect between sex and gambling frequency in relation to gambling problems. Adolescents with ADHD symptoms seem to be more sensitive to gambling, in terms of being susceptible to developing gambling problems. However, once susceptible, adolescents with ADHD symptoms are affected by gambling frequency similarly to other susceptible participants.

Simultaneous topography imaging and broadband nanomechanical mapping on atomic force microscope

NASA Astrophysics Data System (ADS)

Li, Tianwei; Zou, Qingze

2017-12-01

In this paper, an approach is proposed to achieve simultaneous imaging and broadband nanomechanical mapping of soft materials in air by using an atomic force microscope. Simultaneous imaging and nanomechanical mapping are needed, for example, to correlate the morphological and mechanical evolutions of the sample during dynamic phenomena such as the cell endocytosis process. Current techniques for nanomechanical mapping, however, are only capable of capturing static elasticity of the material, or the material viscoelasticity in a narrow frequency band around the resonant frequency(ies) of the cantilever used, not competent for broadband nanomechanical mapping, nor acquiring topography image of the sample simultaneously. These limitations are addressed in this work by enabling the augmentation of an excitation force stimuli of rich frequency spectrum for nanomechanical mapping in the imaging process. Kalman-filtering technique is exploited to decouple and split the mixed signals for imaging and mapping, respectively. Then the sample indentation generated is quantified online via a system-inversion method, and the effects of the indentation generated and the topography tracking error on the topography quantification are taken into account. Moreover, a data-driven feedforward-feedback control is utilized to track the sample topography. The proposed approach is illustrated through experimental implementation on a polydimethylsiloxane sample with a pre-fabricated pattern.

Regional and Seasonal Diet of the Western Burrowing Owl in South-Central Nevada

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

Derek B. Hall, Paul D. Greger, Jeffrey R. Rosier

2009-04-01

We examined diets of Western Burrowing Owls (Athene cunicularia hypugaea) based on contents of pellets and large prey remains collected year-round at burrows in each of the 3 regions in south central Nevada (Mojave Desert, Great Basin Desert, and Transition region). The most common prey items, based on percent frequency of occurrence, were crickets and grasshoppers, beetles, rodents, sun spiders, and scorpions. The most common vertebrate prey was kangaroo rats (Dipodomys spp.). True bugs (Hemiptera), scorpions, and western harvest mice (Reithrodontomys megalotis) occurred most frequently in pellets from the Great Basin Desert region. Kangaroo rats (Dipodomys spp.) and pocket micemore » (Perognathinae) were the most important vertebrate prey items in the Transition and Mojave Desert regions, respectively. Frequency of occurrence of any invertebrate prey was high (>80%) in samples year-round but dropped in winter samples, with scorpions and sun spiders exhibiting the steepest declines. Frequency of occurrence of any vertebrate prey peaked in spring samples, was intermediate for winter and summer samples, and was lowest in fall samples. With the possible exception of selecting for western harvest mice in the Great Basin Desert region, Western Burrowing Owls in our study appeared to be opportunistic foragers with a generalist feeding strategy.« less

A LOW-E MAGIC ANGLE SPINNING PROBE FOR BIOLOGICAL SOLID STATE NMR AT 750 MHz

PubMed Central

McNeill, Seth A.; Gor’kov, Peter L.; Shetty, Kiran; Brey, William W.; Long, Joanna R.

2009-01-01

Crossed-coil NMR probes are a useful tool for reducing sample heating for biological solid state NMR. In a crossed-coil probe, the higher frequency 1H field, which is the primary source of sample heating in conventional probes, is produced by a separate low-inductance resonator. Because a smaller driving voltage is required, the electric field across the sample and the resultant heating is reduced. In this work we describe the development of a magic angle spinning (MAS) solid state NMR probe utilizing a dual resonator. This dual resonator approach, referred to as “Low-E,” was originally developed to reduce heating in samples of mechanically aligned membranes. The study of inherently dilute systems, such as proteins in lipid bilayers, via MAS techniques requires large sample volumes at high field to obtain spectra with adequate signal-to-noise ratio under physiologically relevant conditions. With the Low-E approach, we are able to obtain homogeneous and sufficiently strong radiofrequency fields for both 1H and 13C frequencies in a 4 mm probe with a 1H frequency of 750 MHz. The performance of the probe using windowless dipolar recoupling sequences is demonstrated on model compounds as well as membrane embedded peptides. PMID:19138870

Frequency and structure of stimulant designer drug consumption among suspected drug users in Budapest and South-East Hungary in 2012-2013.

PubMed

Institóris, László; Árok, Zsófia; Seprenyi, Katalin; Varga, Tibor; Sára-Klausz, Gabriella; Keller, Éva; Tóth, Réka A; Sala, Leonardo; Kereszty, Éva; Róna, Kálmán

2015-03-01

Identification of abuse and frequency patterns of stimulant designer drugs (SDDs) provides important information for their risk assessment and legislative control. In the present study urine and/or blood samples of suspected drug users in criminal cases were analysed by GC-MS for 38 SDDs, and for the most frequent illicit and psychoactive licit drugs in Hungary. Between July 2012 and June 2013, 2744 suspected drug users were sampled in Budapest and during 2012 and 2013, 774 persons were sampled in South-East Hungary (Csongrád County - neighbour the Romanian and Serbian borders). In Budapest 71.4% of cases, and in South-East Hungary 61% of cases were positive for at least one substance. Pentedrone was the most frequent SDD in both regions; however, the frequency distribution of the remaining drugs was highly diverse. SDDs were frequently present in combination with other drugs - generally with amphetamine or other stimulants, cannabis and/or benzodiazepines. The quarterly distribution of positive samples indicated remarkable seasonal changes in the frequency and pattern of consumption. Substances placed on the list of illicit drugs (mephedrone, 4-fluoro-amphetamine, MDPV, methylone, 4-MEC) showed a subsequent drop in frequency and were replaced by other SDDs (pentedrone, 3-MMC, methiopropamine, etc.). Newly identified compounds from seized materials were added to the list of new psychoactive substances ("Schedule C"). While the risk assessment of substances listed in Schedule C has to be performed within 2 years after scheduling, continuous monitoring of their presence and frequency among drug users is essential. In summary, our results suggest which substances should be dropped from the list of SDDs measured in biological samples; while the appearance of new substances from seized materials indicate the need for developing adequate standard analytical methods. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Size and modal analyses of fines and ultrafines from some Apollo 17 samples

NASA Technical Reports Server (NTRS)

Greene, G. M.; King, D. T., Jr.; Banholzer, G. S., Jr.; King, E. A.

1975-01-01

Scanning electron and optical microscopy techniques have been used to determine the grain-size frequency distributions and morphology-based modal analyses of fine and ultrafine fractions of some Apollo 17 regolith samples. There are significant and large differences between the grain-size frequency distributions of the less than 10-micron size fraction of Apollo 17 samples, but there are no clear relations to the local geologic setting from which individual samples have been collected. This may be due to effective lateral mixing of regolith particles in this size range by micrometeoroid impacts. None of the properties of the frequency distributions support the idea of selective transport of any fine grain-size fraction, as has been proposed by other workers. All of the particle types found in the coarser size fractions also occur in the less than 10-micron particles. In the size range from 105 to 10 microns there is a strong tendency for the percentage of regularly shaped glass to increase as the graphic mean grain size of the less than 1-mm size fraction decreases, both probably being controlled by exposure age.

Grain size effect on the permittivity of La1.5Sr0.5NiO4 nanoparticles

NASA Astrophysics Data System (ADS)

Dang Thanh, Tran; Van Hong, Le

2009-09-01

Using the annealing at different temperatures the La1.5Sr0.5NiO4 ceramic samples with different mean grain size were manufactured. Mean grain size () of the samples was evaluated by Warren-Averbach method and their SEM images. The obtained results of both methods are almost the same, changing from 16.2 to 95 nm in dependence on the annealing temperature. The frequency dependence of dielectric constant in the frequency range of (1-13 MHz) was recorded for all samples. The real (ɛ') and the imaginary parts (ɛ") of the permittivity of La1.5Sr0.5NiO4 samples abnormally depend on the frequency, exhibiting a dielectric resonance around 500 kHz. R-L-C in series equivalent-circuit fitted well for the obtained result. It was supposed that there exists magnetic contribution in material that suggests the material is a multiferroic one. Dependence of the (ɛ') on the mean grain size supposed that the colossal dielectric property is an intrinsic behaviour of La1.5Sr0.5NiO4 material.

A versatile rotary-stage high frequency probe station for studying magnetic films and devices

NASA Astrophysics Data System (ADS)

He, Shikun; Meng, Zhaoliang; Huang, Lisen; Yap, Lee Koon; Zhou, Tiejun; Panagopoulos, Christos

2016-07-01

We present a rotary-stage microwave probe station suitable for magnetic films and spintronic devices. Two stages, one for field rotation from parallel to perpendicular to the sample plane (out-of-plane) and the other intended for field rotation within the sample plane (in-plane) have been designed. The sample probes and micro-positioners are rotated simultaneously with the stages, which allows the field orientation to cover θ from 0∘ to 90∘ and φ from 0∘ to 360∘. θ and φ being the angle between the direction of current flow and field in a out-of-plane and an in-plane rotation, respectively. The operation frequency is up to 40 GHz and the magnetic field up to 1 T. The sample holder vision system and probe assembly are compactly designed for the probes to land on a wafer with diameter up to 3 cm. Using homemade multi-pin probes and commercially available high frequency probes, several applications including 4-probe DC measurements, the determination of domain wall velocity, and spin transfer torque ferromagnetic resonance are demonstrated.

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

Buxbaum, J.; Pastore, R.; Yaghoubian, R.

Point mutations in the protein transthyretin (TTR) cause familial amyloidosis involving mainly the heart and peripheral nerves. To determine the TTR Ile 122 gene frequency in African Americans, the allele encoding TTR Ile 122 was identified by PCR-Primer Introduced Restriction Analysis of TTR exon 4 and FokI digestion on 1659 control DNA samples from 1659 African Americans: 64 were heterozygous and one homozygous (allele frequency .02). To determine the risk to gene carriers of developing cardiac amyloidosis, immunohistochemical and genetic studies were performed on amyloid-containing samples identified among 52,370 autopsy samples examined over 32 years. In autopsy samples from patientsmore » over age 60, isolated cardiac amyloidosis was more common in African Americans (1.6%) than in White Americans (.40%), suggesting a genetic risk factor. All 29 samples from African Americans were immunohistochemically TTR-positive, and 5 were heterozygous for the TTR Ile 122 allele (17%), as compared with 5/108 heterozygotes (4.6%) among age-matched (over age 60) African American controls without amyloidosis from the same autopsy study (one-tailed P value < .03). Among the 29 amyloid-positive samples were 16 with 1+ or 2+ deposition and 13 with 3+ or 4+ deposition. All 5 TTR Ile 122 heterozygotes had 3+ or 4+ deposition. None of 15 samples from White Americans with cardiac amyloidosis was TTR Ile 122-positive. Extrapolating from the 5/29 samples from which we were able to obtain genetic data, we estimate that 9/54 samples containing cardiac amyloid were TTR Ile 122 heterozygotes. We conclude that heterozygosity for TTR Ile 122 is associated with a greater frequency (relative risk 5.8) and greater severity of cardiac amyloid deposition than in non-carriers of the TTR Ile 122 gene. Of over 40 TTR point mutations associated with amyloidosis described to date, TTR Ile 122 appears to be the most common worldwide and to have the lowest penetrance in causing disease.« less

Activity classification using the GENEA: optimum sampling frequency and number of axes.

PubMed

Zhang, Shaoyan; Murray, Peter; Zillmer, Ruediger; Eston, Roger G; Catt, Michael; Rowlands, Alex V

2012-11-01

The GENEA shows high accuracy for classification of sedentary, household, walking, and running activities when sampling at 80 Hz on three axes. It is not known whether it is possible to decrease this sampling frequency and/or the number of axes without detriment to classification accuracy. The purpose of this study was to compare the classification rate of activities on the basis of data from a single axis, two axes, and three axes, with sampling rates ranging from 5 to 80 Hz. Sixty participants (age, 49.4 yr (6.5 yr); BMI, 24.6 kg·m (3.4 kg·m)) completed 10-12 semistructured activities in the laboratory and outdoor environment while wearing a GENEA accelerometer on the right wrist. We analyzed data from single axis, dual axes, and three axes at sampling rates of 5, 10, 20, 40, and 80 Hz. Mathematical models based on features extracted from mean, SD, fast Fourier transform, and wavelet decomposition were built, which combined one of the numbers of axes with one of the sampling rates to classify activities into sedentary, household, walking, and running. Classification accuracy was high irrespective of the number of axes for data collected at 80 Hz (96.93% ± 0.97%), 40 Hz (97.4% ± 0.73%), 20 Hz (96.86% ± 1.12%), and 10 Hz (97.01% ± 1.01%) but dropped for data collected at 5 Hz (94.98% ± 1.36%). Sampling frequencies >10 Hz and/or more than one axis of measurement were not associated with greater classification accuracy. Lower sampling rates and measurement of a single axis would result in a lower data load, longer battery life, and higher efficiency of data processing. Further research should investigate whether a lower sampling rate and a single axis affects classification accuracy when considering a wider range of activities.

A Study of Moisture Sorption and Dielectric Processes of Starch and Sodium Starch Glycolate : Theme: Formulation and Manufacturing of Solid Dosage Forms Guest Editors: Tony Zhou and Tonglei Li.

PubMed

Hiew, Tze Ning; Huang, Rongying; Popov, Ivan; Feldman, Yuri; Heng, Paul Wan Sia

2017-12-01

This study explored the potential of combining the use of moisture sorption isotherms and dielectric relaxation profiles of starch and sodium starch glycolate (SSG) to probe the location of moisture in dried and hydrated samples. Starch and SSG samples, dried and hydrated, were prepared. For hydrated samples, their moisture contents were determined. The samples were probed by dielectric spectroscopy using a frequency band of 0.1 Hz to 1 MHz to investigate their moisture-related relaxation profiles. The moisture sorption and desorption isotherms of starch and SSG were generated using a vapor sorption analyzer, and modeled using the Guggenheim-Anderson-de Boer equation. A clear high frequency relaxation process was detected in both dried and hydrated starches, while for dried starch, an additional slower low frequency process was also detected. The high frequency relaxation processes in hydrated and dried starches were assigned to the coupled starch-hydrated water relaxation. The low frequency relaxation in dried starch was attributed to the local chain motions of the starch backbone. No relaxation process associated with water was detected in both hydrated and dried SSG within the frequency and temperature range used in this study. The moisture sorption isotherms of SSG suggest the presence of high energy free water, which could have masked the relaxation process of the bound water during dielectric measurements. The combined study of moisture sorption isotherms and dielectric spectroscopy was shown to be beneficial and complementary in probing the effects of moisture on the relaxation processes of starch and SSG.

Method and apparatus for frequency spectrum analysis

NASA Technical Reports Server (NTRS)

Cole, Steven W. (Inventor)

1992-01-01

A method for frequency spectrum analysis of an unknown signal in real-time is discussed. The method is based upon integration of 1-bit samples of signal voltage amplitude corresponding to sine or cosine phases of a controlled center frequency clock which is changed after each integration interval to sweep the frequency range of interest in steps. Integration of samples during each interval is carried out over a number of cycles of the center frequency clock spanning a number of cycles of an input signal to be analyzed. The invention may be used to detect the frequency of at least two signals simultaneously. By using a reference signal of known frequency and voltage amplitude (added to the two signals for parallel processing in the same way, but in a different channel with a sampling at the known frequency and phases of the reference signal), the absolute voltage amplitude of the other two signals may be determined by squaring the sine and cosine integrals of each channel and summing the squares to obtain relative power measurements in all three channels and, from the known voltage amplitude of the reference signal, obtaining an absolute voltage measurement for the other two signals by multiplying the known voltage of the reference signal with the ratio of the relative power of each of the other two signals to the relative power of the reference signal.

Correlation distance dependence of the resonance frequency of intermolecular zero quantum coherences and its implication for MR thermometry.

PubMed

Zhang, Le; McCallister, Andrew; Koshlap, Karl M; Branca, Rosa Tamara

2018-03-01

Because the resonance frequency of water-fat intermolecular zero-quantum coherences (iZQCs) reflects the water-fat frequency separation at the microscopic scale, these frequencies have been proposed and used as a mean to obtain more accurate temperature information. The purpose of this work was to investigate the dependence of the water-fat iZQC resonance frequency on sample microstructure and on the specific choice of the correlation distance. The effect of water-fat susceptibility gradients on the water-methylene iZQC resonance frequency was first computed and then measured for different water-fat emulsions and for a mixture of porcine muscle and fat. Similar measurements were also performed for mixed heteronuclear spin systems. A strong dependence of the iZQC resonance frequency on the sample microstructure and on the specific choice of the correlation distance was found for spin systems like water and fat that do not mix, but not for spin systems that mix at the molecular level. Because water and fat spins do not mix at the molecular level, the water-fat iZQC resonance frequency and its temperature coefficient are not only affected by sample microstructure but also by the specific choice of the correlation distance. Magn Reson Med 79:1429-1438, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Presence of selected chemicals of emerging concern in water and bottom sediment from the St. Louis River, St. Louis Bay, and Superior Bay, Minnesota and Wisconsin, 2010

USGS Publications Warehouse

Christensen, Victoria G.; Lee, Kathy E.; Kieta, Kristen A.; Elliott, Sarah M.

2012-01-01

The St. Louis Bay of Lake Superior receives substantial urban runoff, wastewater treatment plant effluent, and industrial effluent. In 1987, the International Joint Commission designated the St. Louis Bay portion of the lower St. Louis River as one of the Great Lakes Areas of Concern. Concerns exist about the potential effects of chemicals of emerging concern on aquatic biota because many of these chemicals, including endocrine active chemicals, have been shown to affect the endocrine systems of fish. To determine the occurrence of chemicals of emerging concern in the St. Louis River, the St. Louis Bay, and Superior Bay, the U.S. Geological Survey in cooperation with the Minnesota Pollution Control Agency and the Wisconsin Department of Natural Resources collected water and bottom-sediment samples from 40 sites from August through October 2010. The objectives of this study were to (1) identify the extent to which chemicals of emerging concern, including pharmaceuticals, hormones, and other organic chemicals, occur in the St. Louis River, St. Louis Bay, and Superior Bay, and (2) identify the extent to which the chemicals may have accumulated in bottom sediment of the study area. Samples were analyzed for selected wastewater indicators, hormones, sterols, bisphenol A, and human-health pharmaceuticals. During this study, 33 of 89 chemicals of emerging concern were detected among all water samples collected and 56 of 104 chemicals of emerging concern were detected in bottom-sediment samples. The chemical N,N-diethyl-meta-toluamide (DEET) was the most commonly detected chemical in water samples and 2,6-dimethylnaphthalene was the most commonly detected chemical in bottom-sediment samples. In general, chemicals of emerging concern were detected at a higher frequency in bottom-sediment samples than in water samples. Estrone (a steroid hormone) and hexahydrohexamethyl cyclopentabensopyran (a synthetic fragrance) were the most commonly detected endocrine active chemicals in water samples; beta-sitosterol (a plant sterol), estrone, and 4-tert-octylphenol (an alkylphenol) were the most commonly detected endocrine active chemicals in bottom-sediment samples. The greater detection frequency of chemicals in bottom-sediment samples compared to the detection frequency in water samples indicates that bottom sediment is an important sink for chemicals of emerging concern. At least one polycyclic aromatic hydrocarbon was detected in every sample; and in most samples, all nine polycyclic aromatic hydrocarbons included in analyses were detected. Bottom sediment collected from Superior Bay had the most polycyclic aromatic hydrocarbon detections of the sediment sampling locations.

Degree and frequency of inhibition in a routine real-time PCR detecting Pneumocystis jirovecii for the diagnosis of Pneumocystis pneumonia in Turkey.

PubMed

Döskaya, Mert; Caner, Ayse; Degirmenci, Aysu; Wengenack, Nancy L; Yolasigmaz, Aysegül; Turgay, Nevin; Ozensoy Töz, Seray; Gürüz, Yüksel

2011-07-01

Routine laboratory diagnosis of Pneumocystis jirovecii is currently achieved by PCR in almost all laboratories with sufficient equipment due to its high sensitivity and specificity compared to staining methods. A current issue that limits the reliability and sensitivity of PCR is the degree of inhibition caused by inhibitory substances in respiratory samples. The present study aimed to analyse the degree and frequency of inhibition in real-time PCR detecting P. jirovecii in respiratory specimens submitted to a Pneumocystis pneumonia (PcP) diagnosis laboratory in Ege University Medical School, Turkey. Between July 2009 and December 2010, 76 respiratory specimens [63 bronchoalveolar lavage (BAL) fluid, 10 sputum samples, two tracheal aspiration fluid and one thoracentesis fluid] obtained from 69 PcP-suspected patients were investigated for the presence of P. jirovecii using real-time PCR targeting the cdc2 gene. Of these samples, 42 of the specimens were stained and examined by microscopy according to the request of the clinicians. PCR was positive in 15 specimens in the initial run. Of the remaining 61 samples, 41 of them were negative with positive internal inhibition controls (i.e. true-negative group). The frequency of inhibition in the initial run was 26.31 % (20/76) as determined by spiked negative controls. All of the inhibited samples were resolved after 1 : 2, 1 : 5, 1 : 10 and 1 : 20 dilutions. P. jirovecii was detected by PCR in two inhibited specimens after retesting with diluted samples which were also positive by microscopy. The incidence of P. jirovecii in respiratory specimens was 22.36 % (17/76) as determined by real-time PCR and 7.14 % (3/42) by microscopy. Overall, the incidence of P. jirovecii in respiratory samples was 23.68 % (18/76) as detected by both methods. In conclusion, inclusion of spiked positive controls in each sample and retesting with diluted samples to resolve inhibition increased the reliability of the real-time PCR assay in terms of determining false-negative results and influencing the treatment of the patient. Furthermore, results of the present study determined for the first time the frequency and degree of inhibition in a real-time PCR detecting P. jirovecii in respiratory specimens during routine diagnosis of PcP.

Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

DOEpatents

Moore, David S.; Schmidt, Stephen C.

1985-01-01

A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

Visible and infrared polarization ratio spectroreflectometer

NASA Technical Reports Server (NTRS)

Batten, C. E. (Inventor)

1980-01-01

The instrument assists in determining the refractive index and absorption index, at different spectral frequencies, of a solid sample by illuminating the sample at various angles in incidence and measuring the corresponding reflected intensities at various spectral frequencies and polarization angles. The ratio of the intensity of the reflected light for parallel polarized light to that for perpendicular polarized light at two different angles of incidence can be used to determine the optical constants of the sample. The invention involves an apparatus for facilitating the utilization of a wide variety of angles of incidence. The light source and polarizing element are positioned on an outer platform; the sample is positioned on an inner platform. The two platforms rotate about a common axis and cooperate in their rotation such that the sample is rotated one degree for every two degrees of rotation of the light source. This maintains the impingement of the reflected light upon the detector for any angle of incidence without moving or adjusting the detector which allows a continuous change in the angle of incidence.

Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

DOEpatents

Moore, D.S.; Schmidt, S.C.

1983-12-16

A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

Methods for collection and analysis of water samples

USGS Publications Warehouse

Rainwater, Frank Hays; Thatcher, Leland Lincoln

1960-01-01

This manual contains methods used by the U.S. Geological Survey to collect, preserve, and analyze water samples. Throughout, the emphasis is on obtaining analytical results that accurately describe the chemical composition of the water in situ. Among the topics discussed are selection of sampling sites, frequency of sampling, field equipment, preservatives and fixatives, analytical techniques of water analysis, and instruments. Seventy-seven laboratory and field procedures are given for determining fifty-three water properties.

Effect of Sampling Period on Flood Frequency Distributions in the Susquehanna Basin

NASA Astrophysics Data System (ADS)

Kargar, M.; Beighley, R. E.

2010-12-01

Flooding is a devastating natural hazard that claims many human lives and significantly impact regional economies each year. Given the magnitude of flooding impacts, significant resources are dedicated to the development of forecasting models for early warning and evacuation planning, construction of flood defenses (levees/dams) to limit flooding, and the design of civil infrastructure (bridges, culverts, storm sewers) to convey flood flows without failing. In all these cases, it is particularly important to understand the potential flooding risk in terms of both recurrence interval (i.e., return period) and magnitude. Flood frequency analysis (FFA) is a form of risk analysis used to extrapolate the return periods of floods beyond the gauged record. The technique involves using observed annual peak flow discharge data to calculate statistical information such as mean values, standard deviations, skewness, and recurrence intervals. Since discharge data for most catchments have been collected for periods of time less than 100 years, the estimation of the design discharge requires a degree of extrapolation. This study focuses on the assessment and modifications of flood frequency based discharges for sites with limited sampling periods. Here, limited sampling period is intended to capture two issues: (1) limited number of observations to adequately capture the flood frequency signal (i.e., minimum number of annual peaks needed) and (2) climate variability (i.e., sampling period contains primarily “wet” or “dry” periods only). Total of 34 gauges (more than 70 years of data) spread throughout the Susquehanna River basin (71,000 sq km) were used to investigate the impact of sampling period on flood frequency distributions. Data subsets ranging from 10 years to the total number of years available were created from the data for each gauging station. To estimate the flood frequency, the Log Pearson Type III distribution was fit to the logarithms of instantaneous annual peak flows following Bulletin 17B guidelines of the U.S. Interagency Advisory Committee on Water Data. The resulting flood frequencies from these subsets were compared to the results from the entire record at each gauge. Based on the analysis, the minimum number of years required to obtain a reasonable flood frequency distribution was determined for each gauge. In addition, a method to adjust flood frequency distribution at a given gauging station with limited data based on other locations with longer periods of records was developed.

Occurrence of active and inactive herbicide ingredients at selected sites in Iowa

USGS Publications Warehouse

Wang, W.; Liszewski, M.; Buchmiller, R.; Cherryholmes, K.

1995-01-01

Herbicides were detected in 50% of water samples, ranging from 78% of water samples from the Ames site to 25% from the Walnut Creek site. Among herbicides detected, listed in decreasing order of frequency, were atrazine > alachlor > cyanazine > metolachlor > metribuzin. Volatile organic compounds were detected in 11% of water samples. Among the compounds detected, listed in decreasing order of frequency, were xylene > toluene > acetone. One sample contained a detectable amount of aliphatic compound(s), with the empirical formula of C8H18. Results from the Deer Creek site showed that herbicides were detected primarily in the top layer (1.2 m), whereas xylene and other alkylbenzenes were detected at 2.1 m or deeper. Apparently, physico-chemical and other factors are separating herbicides and volatile organic compounds in the shallow unsaturated zone.

[Microsatellite instability and human papilloma virus genotypes in preneoplastic and neoplastic uterine cervix lesions].

PubMed

Roa S, Juan Carlos; Martínez S, Ricardo; Montenegro, Sonia; Roa E, Iván; Capurro V, Italo; Ibacache S, Gilda; Melo A, Angélica

2007-01-01

The association between some specific human papilloma virus (HPV) types and cervix cancer is well known. However, the genetic conditions that favor the development of cervical cancer are less well known. To determine the presence of satellite instability (MSI) in preneoplastic and neoplastic lesions of the cervix and correlate these findings with HPV genotypes. Biopsy samples of cervical lesions were studied. Sixteen had low grade lesions, 22 had high grade lesions and 28 had an epidermoid cancer. Viral types were identified with polymerase chain reaction, dot-blot hybridization and restriction fragment length polymorphism. MSI was determined using a panel of eight highly informative microsatellites. Microsatellite instability in at least one locus was observed in 91, 56 and 69% of low grade lesions, high grade lesions and epidermoid carcinomas, respectively. MSI-High grade, MSI-Low grade instability and microsatellite stability were observed in 5, 60 and 46% of samples, respectively. Two of three samples with high grade instability had HPV 52 genotype. Other viral subtypes had frequencies that ranged from 78% to 100%, with the exception of HPV16 that was present in only 53% of samples with low grade instability. Two thirds of biopsy samples from cervical lesions had MSI, mechanism that can be involved in the first stages of cervical carcinogenesis. The low frequency of high grade instability, its association with HPV52 and the low frequency of HPV16 in samples with low grade instability, suggest different coadjutant mechanisms in cervical carcinogenesis.

Suppression of AC railway power-line interference in ECG signals recorded by public access defibrillators

PubMed Central

Dotsinsky, Ivan

2005-01-01

Background Public access defibrillators (PADs) are now available for more efficient and rapid treatment of out-of-hospital sudden cardiac arrest. PADs are used normally by untrained people on the streets and in sports centers, airports, and other public areas. Therefore, automated detection of ventricular fibrillation, or its exclusion, is of high importance. A special case exists at railway stations, where electric power-line frequency interference is significant. Many countries, especially in Europe, use 16.7 Hz AC power, which introduces high level frequency-varying interference that may compromise fibrillation detection. Method Moving signal averaging is often used for 50/60 Hz interference suppression if its effect on the ECG spectrum has little importance (no morphological analysis is performed). This approach may be also applied to the railway situation, if the interference frequency is continuously detected so as to synchronize the analog-to-digital conversion (ADC) for introducing variable inter-sample intervals. A better solution consists of rated ADC, software frequency measuring, internal irregular re-sampling according to the interference frequency, and a moving average over a constant sample number, followed by regular back re-sampling. Results The proposed method leads to a total railway interference cancellation, together with suppression of inherent noise, while the peak amplitudes of some sharp complexes are reduced. This reduction has negligible effect on accurate fibrillation detection. Conclusion The method is developed in the MATLAB environment and represents a useful tool for real time railway interference suppression. PMID:16309558

Suppression of AC railway power-line interference in ECG signals recorded by public access defibrillators.

PubMed

Dotsinsky, Ivan

2005-11-26

Public access defibrillators (PADs) are now available for more efficient and rapid treatment of out-of-hospital sudden cardiac arrest. PADs are used normally by untrained people on the streets and in sports centers, airports, and other public areas. Therefore, automated detection of ventricular fibrillation, or its exclusion, is of high importance. A special case exists at railway stations, where electric power-line frequency interference is significant. Many countries, especially in Europe, use 16.7 Hz AC power, which introduces high level frequency-varying interference that may compromise fibrillation detection. Moving signal averaging is often used for 50/60 Hz interference suppression if its effect on the ECG spectrum has little importance (no morphological analysis is performed). This approach may be also applied to the railway situation, if the interference frequency is continuously detected so as to synchronize the analog-to-digital conversion (ADC) for introducing variable inter-sample intervals. A better solution consists of rated ADC, software frequency measuring, internal irregular re-sampling according to the interference frequency, and a moving average over a constant sample number, followed by regular back re-sampling. The proposed method leads to a total railway interference cancellation, together with suppression of inherent noise, while the peak amplitudes of some sharp complexes are reduced. This reduction has negligible effect on accurate fibrillation detection. The method is developed in the MATLAB environment and represents a useful tool for real time railway interference suppression.

Dielectric Spectroscopy Study of ZnSe Grown by Physical Vapor Transport

NASA Technical Reports Server (NTRS)

Kokan, J.; Gerhardt, R.; Su, Ching-Hua

1997-01-01

The dielectric properties of ZnSe samples grown by physical vapor transport were measured as a function of frequency. Differences can be seen in the dielectric properties of samples grown under different conditions. The spectra of heat treated samples were also acquired and were found to exhibit significant deviations from those of the as grown crystals.

Using the global positioning system to map disturbance patterns of forest harvesting machinery

Treesearch

T.P. McDonald; E.A. Carter; S.E. Taylor

2002-01-01

Abstract: A method was presented to transform sampled machine positional data obtained from a global positioning system (GPS) receiver into a two-dimensional raster map of number of passes as a function of location. The effect of three sources of error in the transformation process were investigated: path sampling rate (receiver sampling frequency);...

Effect of randomness on multi-frequency aeroelastic responses resolved by Unsteady Adaptive Stochastic Finite Elements

NASA Astrophysics Data System (ADS)

Witteveen, Jeroen A. S.; Bijl, Hester

2009-10-01

The Unsteady Adaptive Stochastic Finite Elements (UASFE) method resolves the effect of randomness in numerical simulations of single-mode aeroelastic responses with a constant accuracy in time for a constant number of samples. In this paper, the UASFE framework is extended to multi-frequency responses and continuous structures by employing a wavelet decomposition pre-processing step to decompose the sampled multi-frequency signals into single-frequency components. The effect of the randomness on the multi-frequency response is then obtained by summing the results of the UASFE interpolation at constant phase for the different frequency components. Results for multi-frequency responses and continuous structures show a three orders of magnitude reduction of computational costs compared to crude Monte Carlo simulations in a harmonically forced oscillator, a flutter panel problem, and the three-dimensional transonic AGARD 445.6 wing aeroelastic benchmark subject to random fields and random parameters with various probability distributions.

Comparison of morphology and phase composition of hydroxyapatite nanoparticles sonochemically synthesized with dual- or single-frequency ultrasonic reactor

NASA Astrophysics Data System (ADS)

Deng, Shi-ting; Yu, Hong; Liu, Di; Bi, Yong-guang

2017-10-01

To investigate how a dual- or single-frequency ultrasonic reactor changes the morphology and phase composition of hydroxyapatite nanoparticles (nHAPs), we designed and constructed the preparation of nHAPs using dual- or single-frequency ultrasonic devices, i.e., the single frequency ultrasonic generator with ultrasonic horn (25 kHz), the ultrasonic bath (40 kHz) and the dual-frequency sonochemical systems combined with the ultrasonic horn and the ultrasonic bath simultaneously (25 + 40 kHz). The results showed that the sonicated samples displayed a more uniform shape with less agglomeration than non-sonicated sample. The rod-shaped particles with 1.66 stoichiometry and without a second phase were synthesized successfully in the ultrasonic bath or horn systems. The nHAPs obtained from the dual-frequency ultrasonic systems exhibited a regular rod-shaped structure with better dispersion and more uniform shapes than those of obtained in either ultrasonic bath or horn systems. Additionally, the size of rod-shaped particles obtained in the dual-frequency ultrasound with a mean width of 35 nm and a mean length of 64 nm was smaller than other samples. A possible mechanism is that the dual-frequency ultrasound significantly enhances the cavitation yield over single frequency ultrasound and thus improves the dispersion of particles and reduces the size of the crystals. In addition, irregular holes can be observed in the nanoparticles obtained in the dual-frequency ultrasound. Therefore, the dual-frequency ultrasonic systems are expected to become a convenient, efficient and environmentally friendly synthetic technology to obtain well-defined nHAPs for specific biomedical applications.

Cavity-locked ring down spectroscopy

DOEpatents

Zare, Richard N.; Paldus, Barbara A.; Harb, Charles C.; Spence, Thomas

2000-01-01

Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

A non-uniformly under-sampled blade tip-timing signal reconstruction method for blade vibration monitoring.

PubMed

Hu, Zheng; Lin, Jun; Chen, Zhong-Sheng; Yang, Yong-Min; Li, Xue-Jun

2015-01-22

High-speed blades are often prone to fatigue due to severe blade vibrations. In particular, synchronous vibrations can cause irreversible damages to the blade. Blade tip-timing methods (BTT) have become a promising way to monitor blade vibrations. However, synchronous vibrations are unsuitably monitored by uniform BTT sampling. Therefore, non-equally mounted probes have been used, which will result in the non-uniformity of the sampling signal. Since under-sampling is an intrinsic drawback of BTT methods, how to analyze non-uniformly under-sampled BTT signals is a big challenge. In this paper, a novel reconstruction method for non-uniformly under-sampled BTT data is presented. The method is based on the periodically non-uniform sampling theorem. Firstly, a mathematical model of a non-uniform BTT sampling process is built. It can be treated as the sum of certain uniform sample streams. For each stream, an interpolating function is required to prevent aliasing in the reconstructed signal. Secondly, simultaneous equations of all interpolating functions in each sub-band are built and corresponding solutions are ultimately derived to remove unwanted replicas of the original signal caused by the sampling, which may overlay the original signal. In the end, numerical simulations and experiments are carried out to validate the feasibility of the proposed method. The results demonstrate the accuracy of the reconstructed signal depends on the sampling frequency, the blade vibration frequency, the blade vibration bandwidth, the probe static offset and the number of samples. In practice, both types of blade vibration signals can be particularly reconstructed by non-uniform BTT data acquired from only two probes.

Influences of sampling effort on detected patterns and structuring processes of a Neotropical plant-hummingbird network.

PubMed

Vizentin-Bugoni, Jeferson; Maruyama, Pietro K; Debastiani, Vanderlei J; Duarte, L da S; Dalsgaard, Bo; Sazima, Marlies

2016-01-01

Virtually all empirical ecological interaction networks to some extent suffer from undersampling. However, how limitations imposed by sampling incompleteness affect our understanding of ecological networks is still poorly explored, which may hinder further advances in the field. Here, we use a plant-hummingbird network with unprecedented sampling effort (2716 h of focal observations) from the Atlantic Rainforest in Brazil, to investigate how sampling effort affects the description of network structure (i.e. widely used network metrics) and the relative importance of distinct processes (i.e. species abundances vs. traits) in determining the frequency of pairwise interactions. By dividing the network into time slices representing a gradient of sampling effort, we show that quantitative metrics, such as interaction evenness, specialization (H2 '), weighted nestedness (wNODF) and modularity (Q; QuanBiMo algorithm) were less biased by sampling incompleteness than binary metrics. Furthermore, the significance of some network metrics changed along the sampling effort gradient. Nevertheless, the higher importance of traits in structuring the network was apparent even with small sampling effort. Our results (i) warn against using very poorly sampled networks as this may bias our understanding of networks, both their patterns and structuring processes, (ii) encourage the use of quantitative metrics little influenced by sampling when performing spatio-temporal comparisons and (iii) indicate that in networks strongly constrained by species traits, such as plant-hummingbird networks, even small sampling is sufficient to detect their relative importance for the frequencies of interactions. Finally, we argue that similar effects of sampling are expected for other highly specialized subnetworks. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

A Non-Uniformly Under-Sampled Blade Tip-Timing Signal Reconstruction Method for Blade Vibration Monitoring

PubMed Central

Hu, Zheng; Lin, Jun; Chen, Zhong-Sheng; Yang, Yong-Min; Li, Xue-Jun

2015-01-01

High-speed blades are often prone to fatigue due to severe blade vibrations. In particular, synchronous vibrations can cause irreversible damages to the blade. Blade tip-timing methods (BTT) have become a promising way to monitor blade vibrations. However, synchronous vibrations are unsuitably monitored by uniform BTT sampling. Therefore, non-equally mounted probes have been used, which will result in the non-uniformity of the sampling signal. Since under-sampling is an intrinsic drawback of BTT methods, how to analyze non-uniformly under-sampled BTT signals is a big challenge. In this paper, a novel reconstruction method for non-uniformly under-sampled BTT data is presented. The method is based on the periodically non-uniform sampling theorem. Firstly, a mathematical model of a non-uniform BTT sampling process is built. It can be treated as the sum of certain uniform sample streams. For each stream, an interpolating function is required to prevent aliasing in the reconstructed signal. Secondly, simultaneous equations of all interpolating functions in each sub-band are built and corresponding solutions are ultimately derived to remove unwanted replicas of the original signal caused by the sampling, which may overlay the original signal. In the end, numerical simulations and experiments are carried out to validate the feasibility of the proposed method. The results demonstrate the accuracy of the reconstructed signal depends on the sampling frequency, the blade vibration frequency, the blade vibration bandwidth, the probe static offset and the number of samples. In practice, both types of blade vibration signals can be particularly reconstructed by non-uniform BTT data acquired from only two probes. PMID:25621612

Low-frequency dynamic response of the bismuth strontium ferrite (Bi,Sr)FeO3- x

NASA Astrophysics Data System (ADS)

Pronin, A. A.; Torgashev, V. I.; Bush, A. A.; Gorshunov, B. P.; Volkov, A. A.; Prokhorov, A. S.

2009-03-01

Broad-range measurements of the dynamic response of polycrystalline samples of the (Bi,Sr)FeO3- x perovskite-like solid solution are performed over a frequency range from 10 Hz to 1 GHz at temperatures of 100-300 K for the first time. The colossal dielectric constant effect and the influence of electric contacts on the results of measurements are considered. It is shown that the frequency dependences of the permittivity and dynamic conductivity of (Bi,Sr)FeO3- x samples can be described within the universal dielectric response model.

Note: An approach to measurement of low frequency oscillation amplitude of discharge current of in-orbit Hall thruster.

PubMed

Han, Liang; Ding, Yongjie; Wei, Liqiu; Yu, Daren

2014-06-01

This paper provides a method to measure the amplitude of low frequency oscillation under the on-track working condition, and realizes the sampling by means of adding the circuit design of sampling, low pass filtering by 3 dB at 48.2 kHz, detection and integrating in the filtering unit. The experimental results prove that the measuring device of merely 0.8 g can quantitatively reflect the amplitude of low frequency oscillation in Hall thruster and the maximum deviation of experiment data and theory data is 10% FS.

Mode synthesizing atomic force microscopy and mode-synthesizing sensing

DOEpatents

Passian, Ali; Thundat, Thomas George; Tetard, Laurene

2013-05-17

A method of analyzing a sample that includes applying a first set of energies at a first set of frequencies to a sample and applying, simultaneously with the applying the first set of energies, a second set of energies at a second set of frequencies, wherein the first set of energies and the second set of energies form a multi-mode coupling. The method further includes detecting an effect of the multi-mode coupling.

Mode-synthesizing atomic force microscopy and mode-synthesizing sensing

DOEpatents

Passain, Ali; Thundat, Thomas George; Tetard, Laurene

2014-07-22

A method of analyzing a sample that includes applying a first set of energies at a first set of frequencies to a sample and applying, simultaneously with the applying the first set of energies, a second set of energies at a second set of frequencies, wherein the first set of energies and the second set of energies form a multi-mode coupling. The method further includes detecting an effect of the multi-mode coupling.

Measuring saccade peak velocity using a low-frequency sampling rate of 50 Hz.

PubMed

Wierts, Roel; Janssen, Maurice J A; Kingma, Herman

2008-12-01

During the last decades, small head-mounted video eye trackers have been developed in order to record eye movements. Real-time systems-with a low sampling frequency of 50/60 Hz-are used for clinical vestibular practice, but are generally considered not to be suited for measuring fast eye movements. In this paper, it is shown that saccadic eye movements, having an amplitude of at least 5 degrees, can, in good approximation, be considered to be bandwidth limited up to a frequency of 25-30 Hz. Using the Nyquist theorem to reconstruct saccadic eye movement signals at higher temporal resolutions, it is shown that accurate values for saccade peak velocities, recorded at 50 Hz, can be obtained, but saccade peak accelerations and decelerations cannot. In conclusion, video eye trackers sampling at 50/60 Hz are appropriate for detecting the clinical relevant saccade peak velocities in contrast to what has been stated up till now.

Influence of the pore fluid on the phase velocity in bovine trabecular bone In Vitro: Prediction of the biot model

NASA Astrophysics Data System (ADS)

Lee, Kang Il

2013-01-01

The present study aims to investigate the influence of the pore fluid on the phase velocity in bovine trabecular bone in vitro. The frequency-dependent phase velocity was measured in 20 marrow-filled and water-filled bovine femoral trabecular bone samples. The mean phase velocities at frequencies between 0.6 and 1.2 MHz exhibited significant negative dispersions for both the marrow-filled and the water-filled samples. The magnitudes of the dispersions showed no significant differences between the marrow-filled and the water-filled samples. In contrast, replacement of marrow by water led to a mean increase in the phase velocity of 27 m/s at frequencies from 0.6 to 1.2 MHz. The theoretical phase velocities of the fast wave predicted by using the Biot model for elastic wave propagation in fluid-saturated porous media showed good agreements with the measurements.

Contact resonance atomic force microscopy imaging in air and water using photothermal excitation

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

Kocun, Marta; Labuda, Aleksander; Gannepalli, Anil

2015-08-15

Contact Resonance Force Microscopy (CR-FM) is a leading atomic force microscopy technique for measuring viscoelastic nano-mechanical properties. Conventional piezo-excited CR-FM measurements have been limited to imaging in air, since the “forest of peaks” frequency response associated with acoustic excitation methods effectively masks the true cantilever resonance. Using photothermal excitation results in clean contact, resonance spectra that closely match the ideal frequency response of the cantilever, allowing unambiguous and simple resonance frequency and quality factor measurements in air and liquids alike. This extends the capabilities of CR-FM to biologically relevant and other soft samples in liquid environments. We demonstrate CR-FM inmore » air and water on both stiff silicon/titanium samples and softer polystyrene-polyethylene-polypropylene polymer samples with the quantitative moduli having very good agreement between expected and measured values.« less

Tape recorder effects on jitter and shimmer extraction.

PubMed

Doherty, E T; Shipp, T

1988-09-01

To test for possible contamination of acoustic analyses by record/reproduce systems, five sine waves of fixed frequency and amplitude were sampled directly by a computer and recorded simultaneously on four different tape formats (audio and FM reel-to-reel, audio cassette, and video cassette using pulse code modulation). Recordings were digitized on playback and with the direct samples analyzed for fundamental frequency, amplitude, jitter, and shimmer using a zero crossing interpolation scheme. Distortion introduced by any of the data acquisition systems is negligible when extracting average fundamental frequency or average amplitude. For jitter and shimmer estimation, direct sampling or the use of a video cassette recorder with pulse code modulation are clearly superior. FM recorders, although not quite as accurate, provide a satisfactory alternative to those methods. Audio reel-to-reel recordings are marginally adequate for jitter analysis whereas audio cassette recorders can introduce jitter and shimmer values that are greater than some reported values for normal talkers.

Alternating current circuit theory and pulsed NMR (Nuclear Magnetic Resonance)

NASA Astrophysics Data System (ADS)

Gerstein, B. C.

1987-06-01

Pulsed NMR, by definition, deals with time varying excitations. These excitations, supplied by resonant circuits which provide a pulse of radiofrequency (frequencies in the megahertz region) power to a resonant circuit containing, among other things, a coil of wire, or inductor, in which a sample under investigation is placed for purposes of the nuclear magnetic resonance experiment. There are therefore two features of the pulse NMR experiment. First is the fact that we have available a source of continuous wave (CW) alternating current at some angular frequency, omega, measured in radians per second. This source is generally supplied by an ultrastable device called a frequency synthesizer. The second feature of the pulsed NMR experiment is that the sample is not continuously irradiated, but a pulse of radiofrequency oscillation is applied to the sample. This report discusses alternating current theory, resonant circuits and the equipment used in this experiment.

The Coalescent Process in Models with Selection

PubMed Central

Kaplan, N. L.; Darden, T.; Hudson, R. R.

1988-01-01

Statistical properties of the process describing the genealogical history of a random sample of genes are obtained for a class of population genetics models with selection. For models with selection, in contrast to models without selection, the distribution of this process, the coalescent process, depends on the distribution of the frequencies of alleles in the ancestral generations. If the ancestral frequency process can be approximated by a diffusion, then the mean and the variance of the number of segregating sites due to selectively neutral mutations in random samples can be numerically calculated. The calculations are greatly simplified if the frequencies of the alleles are tightly regulated. If the mutation rates between alleles maintained by balancing selection are low, then the number of selectively neutral segregating sites in a random sample of genes is expected to substantially exceed the number predicted under a neutral model. PMID:3066685

Evaluation of the Problem Behavior Frequency Scale-Teacher Report Form for Assessing Behavior in a Sample of Urban Adolescents.

PubMed

Farrell, Albert D; Goncy, Elizabeth A; Sullivan, Terri N; Thompson, Erin L

2018-02-01

This study evaluated the structure and validity of the Problem Behavior Frequency Scale-Teacher Report Form (PBFS-TR) for assessing students' frequency of specific forms of aggression and victimization, and positive behavior. Analyses were conducted on two waves of data from 727 students from two urban middle schools (Sample 1) who were rated by their teachers on the PBFS-TR and the Social Skills Improvement System (SSIS), and on data collected from 1,740 students from three urban middle schools (Sample 2) for whom data on both the teacher and student report version of the PBFS were obtained. Confirmatory factor analyses supported first-order factors representing 3 forms of aggression (physical, verbal, and relational), 3 forms of victimization (physical, verbal and relational), and 2 forms of positive behavior (prosocial behavior and effective nonviolent behavior), and higher-order factors representing aggression, victimization, and positive behavior. Strong measurement invariance was established over gender, grade, intervention condition, and time. Support for convergent validity was found based on correlations between corresponding scales on the PBFS-TR and teacher ratings on the SSIS in Sample 1. Significant correlations were also found between teacher ratings on the PBFS-TR and student ratings of their behavior on the Problem Behavior Frequency Scale-Adolescent Report (PBFS-AR) and a measure of nonviolent behavioral intentions in Sample 2. Overall the findings provided support for the PBFS-TR and suggested that teachers can provide useful data on students' aggressive and prosocial behavior and victimization experiences within the school setting. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Failure to Replicate a Genetic Association May Provide Important Clues About Genetic Architecture

PubMed Central

Greene, Casey S.; Penrod, Nadia M.; Williams, Scott M.; Moore, Jason H.

2009-01-01

Replication has become the gold standard for assessing statistical results from genome-wide association studies. Unfortunately this replication requirement may cause real genetic effects to be missed. A real result can fail to replicate for numerous reasons including inadequate sample size or variability in phenotype definitions across independent samples. In genome-wide association studies the allele frequencies of polymorphisms may differ due to sampling error or population differences. We hypothesize that some statistically significant independent genetic effects may fail to replicate in an independent dataset when allele frequencies differ and the functional polymorphism interacts with one or more other functional polymorphisms. To test this hypothesis, we designed a simulation study in which case-control status was determined by two interacting polymorphisms with heritabilities ranging from 0.025 to 0.4 with replication sample sizes ranging from 400 to 1600 individuals. We show that the power to replicate the statistically significant independent main effect of one polymorphism can drop dramatically with a change of allele frequency of less than 0.1 at a second interacting polymorphism. We also show that differences in allele frequency can result in a reversal of allelic effects where a protective allele becomes a risk factor in replication studies. These results suggest that failure to replicate an independent genetic effect may provide important clues about the complexity of the underlying genetic architecture. We recommend that polymorphisms that fail to replicate be checked for interactions with other polymorphisms, particularly when samples are collected from groups with distinct ethnic backgrounds or different geographic regions. PMID:19503614

Using the simple sample count to estimate the frequency of prescription drug neuroenhancement in a sample of Jordan employees.

PubMed

Wolff, Wanja; Sandouqa, Yaser; Brand, Ralf

2016-05-01

Epidemiological research indicates that the use of prescription drugs to enhance cognitive functioning is prevalent in Western countries, however, research on this phenomenon in Arab countries is lacking. Our study aimed to investigate the frequency of neuroenhancement (NE) using prescription drugs in a sample of employees in Jordan. A sample of 1186 employees (37.11±8.37 years old, 495 female), of whom 723 (35.65±7.53 years old, 396 female) served as teachers, completed a paper-pencil questionnaire. The single sample count technique (SSC) was used in order to secure confidential, self-reporting of prescription drug NE. The 12-month prevalence of NE, estimated with the SSC was 15.43%. At 26.16%, the prevalence estimate was markedly higher in the subsample of teachers compared to non-teachers, 0.29%. Surprisingly, 336 participants did not use the SSC and directly affirmed or denied prescription drug NE. These direct responses yielded a prevalence of 11.57% for the full sample, 9.73% for the teachers and 15.60% for the non-teachers. This is the first study of the frequency of NE in an Arab sample. Results indicate that the use of prescription drug NE is not limited to Western countries and that teachers in Jordan might constitute a high-risk population. Further, participants seem to differ in their use of indirect estimation methods for reporting prescription drug NE. For future research, it might be useful to triangulate standard self-reports and indirect estimation methods to assess NE. Possible cultural differences and specific high-risk populations for NE should be investigated further. Copyright © 2015 Elsevier B.V. All rights reserved.

Subjecting appropriate lung adenocarcinoma samples to next-generation sequencing-based molecular testing: challenges and possible solutions.

PubMed

Li, Weihua; Qiu, Tian; Ling, Yun; Gao, Shugeng; Ying, Jianming

2018-05-01

Next-generation sequencing (NGS) has recently been rapidly adopted in the molecular diagnosis of cancer, but it still faces some obstacles. In this study, 665 lung adenocarcinoma samples (558 TKI-naive and 107 TKI-relapsed samples) were interrogated using NGS, and the challenges and possible solutions of subjecting appropriate tissue samples to NGS testing were explored. The results showed that lower frequencies of HER2/BRAF/PIK3CA and acquired EGFR T790M mutations were observed in biopsy samples with <20% tumor cellularity than in those with ≥20%, but there were no significant differences in the frequencies of EGFR or KRAS mutations. Moreover, tumor heterogeneity was assessed by heterogeneity score (HS), which was calculated through multiplying by 2 the mutant allele frequency (MAF) of tumor cells. In TKI-naive samples, intratumor heterogeneity could occur in EGFR, KRAS, HER2, BRAF, and PIK3CA mutant tumors, but the degree was variable. Higher EGFR, but lower BRAF and PIK3CA HS values were observed compared with KRAS HS. In TKI-relapsed samples, analysis of concomitant sensitizing EGFR and T790M MAFs showed that intratumor heterogeneity was common in acquired EGFR T790M mutant tumors. The mutational status between primary and metastatic tumors was usually concordant, but KRAS, HER2, and PIK3CA HS were significantly higher in metastatic tumors than in primary tumors. Additionally, the discordance rate of mutational status in multifocal lung adenocarcinomas diagnosed as equivocal or multiple primary tumors was high. Together, our findings demonstrate that a comprehensive quality assessment is necessary during tissue process to mitigate the challenges of poor tumor cellularity, tumor heterogeneity, and multifocal clonally independent tumors. © 2018 The Authors. Published by FEBS Press and John Wiley & Sons Ltd.

[Frequency of Candida in root canals of teeth with primary and persistent endodontic infections].

PubMed

Bernal-Treviño, Angel; González-Amaro, Ana María; Méndez González, Verónica; Pozos-Guillen, Amaury

Microbiological identification in endodontic infections has focused mainly on bacteria without giving much attention to yeasts, which, due to their virulence factors, can affect the outcomes of root canal treatment. To determine the frequency of Candida in anaerobic conditions in root canals with primary and persistent endodontic infection, as well as to evaluate a microbiological sampling method using aspiration compared to the traditional absorption method with paper points. Fifty microbiological samples were obtained from teeth of 47 patients requiring endodontic treatments, due to either primary or persistent infections. Two microbiological sampling methods were used: an aspiration method, and the traditional paper point absorption method. In each of these methods, two types of medium were used (M 1 -M 4 ). Samples were cultured under anaerobic conditions until reaching 0.5 McFarland turbidity, and then inoculated on Sabouraud dextrose, as well as on anaerobic enriched blood agar plates. Macroscopic and microscopic observations of the colonies were performed. The germ-tube test, growth on CHROMagar, and biochemical identification were performed on the isolated yeasts. Fungal infection was found in 18 (36%) samples out of the 50 teeth evaluated. In the 18 samples positive for fungal infection, 15 out of 36 (41.6%) teeth were taken from a primary infection, and 3 out of 14 (21.4%) from a persistent infection. The aspiration method using Sabouraud dextrose medium recovered a greater diversity of species. Yeasts frequency was higher in teeth with primary infections compared to teeth with persistent infections. The predominant yeast species was Candida albicans. The aspirating sampling method was more efficient in the recovery of Candida isolates than the traditional absorption method. Copyright © 2018 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Dissipative and electrostatic force spectroscopy of indium arsenide quantum dots by non-contact atomic force microscopy

NASA Astrophysics Data System (ADS)

Stomp, Romain-Pierre

This thesis is devoted to the studies of self-assembled InAs quantum dots (QD) by low-temperature Atomic Force Microscopy (AFM) in frequency modulation mode. Several spectroscopic methods are developed to investigate single electron charging from a two-dimensional electron gas (2DEG) to an individual InAs QD. Furthermore, a new technique to measure the absolute tip-sample capacitance is also demonstrated. The main observables are the electrostatic force between the metal-coated AFM tip and sample as well as the sample-induced energy dissipation, and therefore no tunneling current has to be collected at the AFM tip. Measurements were performed by recording simultaneously the shift in the resonant frequency and the Q-factor degradation of the oscillating cantilever either as a function of tip-sample voltage or distance. The signature of single electron charging was detected as an abrupt change in the frequency shift as well as corresponding peaks in the dissipation. The main experimental features in the force agree well with the semi-classical theory of Coulomb blockade by considering the free energy of the system. The observed dissipation peaks can be understood as a back-action effect on the oscillating cantilever beam due to the fluctuation in time of electrons tunneling back and forth between the 2DEG and the QD. It was also possible to extract the absolute value of the tip-sample capacitance, as a consequence of the spectroscopic analysis of the electrostic force as a function of tip-sample distance for different values of the applied voltage. At the same time, the contact potential difference and the residual non-capacitive force could also be determined as a function of tip-sample distance.

Human toxocariasis: frequency of anti-Toxocara antibodies in children and adolescents from an outpatient clinic for lymphatic filariasis in Recife, Northeast Brazil.

PubMed

Aguiar-Santos, Ana Maria; Andrade, Luiz D; Medeiros, Zulma; Chieffi, Pedro Paulo; Lescano, Suzana Z; Perez, Emília P

2004-01-01

In a transversal study on a sample of 386 children and adolescents from an outpatient clinic for filariasis in Recife, Northeast Brazil, the frequency of anti-Toxocara antibodies and its relation to age, gender, number of peripheral eosinophils, Wuchereria bancrofti microfilariae and intestinal helminths was determined. The total anti-Toxocara IgG antibody frequency was 39.4%, by ELISA technique. The difference in frequency between males (40.1%) and females (37.6%) was not statistically significant. The 6 to 10-year-old subset presented the highest frequency of anti-Toxocara antibodies (60%), and within this age group there was a statistically significant male bias. There was also a significant association between the number of eosinophils and the presence of anti-Toxocara antibodies. Intestinal parasite frequency was 52.1%, but no association was found between this data and the presence of anti-Toxocara antibodies. In the present sample, 42.2% of the patients were Wuchereria bancrofti carriers, however, again this was not associated with the presence of anti-Toxocara antibodies. In conclusion, anti-Toxocara antibodies were highly prevalent in this sample. The present data show that there is no cross correlation between anti-Toxocara IgG antibody and the presence of intestinal helminths and filariasis.

Sparse Representation Based Frequency Detection and Uncertainty Reduction in Blade Tip Timing Measurement for Multi-Mode Blade Vibration Monitoring

PubMed Central

Pan, Minghao; Yang, Yongmin; Guan, Fengjiao; Hu, Haifeng; Xu, Hailong

2017-01-01

The accurate monitoring of blade vibration under operating conditions is essential in turbo-machinery testing. Blade tip timing (BTT) is a promising non-contact technique for the measurement of blade vibrations. However, the BTT sampling data are inherently under-sampled and contaminated with several measurement uncertainties. How to recover frequency spectra of blade vibrations though processing these under-sampled biased signals is a bottleneck problem. A novel method of BTT signal processing for alleviating measurement uncertainties in recovery of multi-mode blade vibration frequency spectrum is proposed in this paper. The method can be divided into four phases. First, a single measurement vector model is built by exploiting that the blade vibration signals are sparse in frequency spectra. Secondly, the uniqueness of the nonnegative sparse solution is studied to achieve the vibration frequency spectrum. Thirdly, typical sources of BTT measurement uncertainties are quantitatively analyzed. Finally, an improved vibration frequency spectra recovery method is proposed to get a guaranteed level of sparse solution when measurement results are biased. Simulations and experiments are performed to prove the feasibility of the proposed method. The most outstanding advantage is that this method can prevent the recovered multi-mode vibration spectra from being affected by BTT measurement uncertainties without increasing the probe number. PMID:28758952

300 Area TEDF NPDES Permit Compliance Monitoring Plan

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

Loll, C.M.

1994-10-13

This monitoring plan describes the activities and methods that will be employed at the 300 Area Treated Effluent Disposal Facility (TEDF) in order to ensure compliance with the National Discharge Elimination System (NPDES) permit. Included in this document are a brief description of the project, the specifics of the sampling effort, including the physical location and frequency of sampling, the support required for sampling, and the Quality Assurance (QA) protocols to be followed in the sampling procedures.

Correlation of enterohemorrhagic Escherichia coli O157 prevalence in feces, hides, and carcasses of beef cattle during processing.

PubMed

Elder, R O; Keen, J E; Siragusa, G R; Barkocy-Gallagher, G A; Koohmaraie, M; Laegreid, W W

2000-03-28

A survey was performed to estimate the frequency of enterohemorrhagic Escherichia coli O157:H7 or O157:nonmotile (EHEC O157) in feces and on hides within groups of fed cattle from single sources (lots) presented for slaughter at meat processing plants in the Midwestern United States, as well as frequency of carcass contamination during processing from cattle within the same lots. Of 29 lots sampled, 72% had at least one EHEC O157-positive fecal sample and 38% had positive hide samples. Overall, EHEC O157 prevalence in feces and on hides was 28% (91 of 327) and 11% (38 of 355), respectively. Carcass samples were taken at three points during processing: preevisceration, postevisceration before antimicrobial intervention, and postprocessing after carcasses entered the cooler. Of 30 lots sampled, 87% had at least one EHEC O157-positive preevisceration sample, 57% of lots were positive postevisceration, and 17% had positive postprocessing samples. Prevalence of EHEC O157 in the three postprocessing samples was 43% (148 of 341), 18% (59 of 332) and 2% (6 of 330), respectively. Reduction in carcass prevalence from preevisceration to postprocessing suggests that sanitary procedures were effective within the processing plants. Fecal and hide prevalence were significantly correlated with carcass contamination (P = 0.001), indicating a role for control of EHEC O157 in live cattle.

Frequent Shifts in Aspergillus flavus Populations Associated with Maize Production in Sonora, Mexico.

PubMed

Ortega-Beltran, A; Cotty, P J

2018-03-01

Aspergillus flavus frequently contaminates maize, a critical staple for billions of people, with aflatoxins. Diversity among A. flavus L morphotype populations associated with maize in Sonora, Mexico was assessed and, in total, 869 isolates from 83 fields were placed into 136 vegetative compatibility groups (VCGs) using nitrate-nonutilizing mutants. VCG diversity indices did not differ in four agroecosystems (AES) but diversity significantly differed among years. Frequencies of certain VCGs changed manyfold over single years in both multiple fields and multiple AES. Certain VCGs were highly frequent (>1%) in 2006 but frequencies declined repeatedly in each of the two subsequent years. Other VCGs that had low frequencies in 2006 increased in 2007 and subsequently declined. None of the VCGs were consistently associated with any AES. Fourteen VCGs were considered dominant in at least a single year. However, frequencies often varied significantly among years. Only 9% of VCGs were detected all 3 years whereas 66% were detected in only 1 year. Results suggest that the most realistic measurements of both genetic diversity and the frequency of A. flavus VCGs are obtained by sampling multiple locations in multiple years. Single-season sampling in many locations should not be substituted for sampling over multiple years.

Mechanical properties of porcine brain tissue in vivo and ex vivo estimated by MR elastography.

PubMed

Guertler, Charlotte A; Okamoto, Ruth J; Schmidt, John L; Badachhape, Andrew A; Johnson, Curtis L; Bayly, Philip V

2018-03-01

The mechanical properties of brain tissue in vivo determine the response of the brain to rapid skull acceleration. These properties are thus of great interest to the developers of mathematical models of traumatic brain injury (TBI) or neurosurgical simulations. Animal models provide valuable insight that can improve TBI modeling. In this study we compare estimates of mechanical properties of the Yucatan mini-pig brain in vivo and ex vivo using magnetic resonance elastography (MRE) at multiple frequencies. MRE allows estimations of properties in soft tissue, either in vivo or ex vivo, by imaging harmonic shear wave propagation. Most direct measurements of brain mechanical properties have been performed using samples of brain tissue ex vivo. It has been observed that direct estimates of brain mechanical properties depend on the frequency and amplitude of loading, as well as the time post-mortem and condition of the sample. Using MRE in the same animals at overlapping frequencies, we observe that porcine brain tissue in vivo appears stiffer than porcine brain tissue samples ex vivo at frequencies of 100 Hz and 125 Hz, but measurements show closer agreement at lower frequencies. Copyright © 2018 Elsevier Ltd. All rights reserved.

Parametric Amplification Protocol for Frequency-Modulated Magnetic Resonance Force Microscopy Signals

NASA Astrophysics Data System (ADS)

Harrell, Lee; Moore, Eric; Lee, Sanggap; Hickman, Steven; Marohn, John

2011-03-01

We present data and theoretical signal and noise calculations for a protocol using parametric amplification to evade the inherent tradeoff between signal and detector frequency noise in force-gradient magnetic resonance force microscopy signals, which are manifested as a modulated frequency shift of a high- Q microcantilever. Substrate-induced frequency noise has a 1 / f frequency dependence, while detector noise exhibits an f2 dependence on modulation frequency f . Modulation of sample spins at a frequency that minimizes these two contributions typically results in a surface frequency noise power an order of magnitude or more above the thermal limit and may prove incompatible with sample spin relaxation times as well. We show that the frequency modulated force-gradient signal can be used to excite the fundamental resonant mode of the cantilever, resulting in an audio frequency amplitude signal that is readily detected with a low-noise fiber optic interferometer. This technique allows us to modulate the force-gradient signal at a sufficiently high frequency so that substrate-induced frequency noise is evaded without subjecting the signal to the normal f2 detector noise of conventional demodulation.

Flexible metamaterial absorbers for stealth applications at terahertz frequencies.

PubMed

Iwaszczuk, Krzysztof; Strikwerda, Andrew C; Fan, Kebin; Zhang, Xin; Averitt, Richard D; Jepsen, Peter Uhd

2012-01-02

We have wrapped metallic cylinders with strongly absorbing metamaterials. These resonant structures, which are patterned on flexible substrates, smoothly coat the cylinder and give it an electromagnetic response designed to minimize its radar cross section. We compare the normal-incidence, small-beam reflection coefficient with the measurement of the far-field bistatic radar cross section of the sample, using a quasi-planar THz wave with a beam diameter significantly larger than the sample dimensions. In this geometry we demonstrate a near-400-fold reduction of the radar cross section at the design frequency of 0.87 THz. In addition we discuss the effect of finite sample dimensions and the spatial dependence of the reflection spectrum of the metamaterial.

On the origin of amplitude reduction mechanism in tapping mode atomic force microscopy

NASA Astrophysics Data System (ADS)

Keyvani, Aliasghar; Sadeghian, Hamed; Goosen, Hans; van Keulen, Fred

2018-04-01

The origin of amplitude reduction in Tapping Mode Atomic Force Microscopy (TM-AFM) is typically attributed to the shift in resonance frequency of the cantilever due to the nonlinear tip-sample interactions. In this paper, we present a different insight into the same problem which, besides explaining the amplitude reduction mechanism, provides a simple reasoning for the relationship between tip-sample interactions and operation parameters (amplitude and frequency). The proposed formulation, which attributes the amplitude reduction to an interference between the tip-sample and dither force, only deals with the linear part of the system; however, it fully agrees with experimental results and numerical solutions of the full nonlinear model of TM-AFM.

Real time flight simulation methodology

NASA Technical Reports Server (NTRS)

Parrish, E. A.; Cook, G.; Mcvey, E. S.

1976-01-01

An example sensitivity study is presented to demonstrate how a digital autopilot designer could make a decision on minimum sampling rate for computer specification. It consists of comparing the simulated step response of an existing analog autopilot and its associated aircraft dynamics to the digital version operating at various sampling frequencies and specifying a sampling frequency that results in an acceptable change in relative stability. In general, the zero order hold introduces phase lag which will increase overshoot and settling time. It should be noted that this solution is for substituting a digital autopilot for a continuous autopilot. A complete redesign could result in results which more closely resemble the continuous results or which conform better to original design goals.

Population data for 15 Y-chromosome STRs in a population sample from Quito (Ecuador).

PubMed

Baeza, Carlos; Guzmán, Rodrigo; Tirado, Miriam; López-Parra, Ana María; Rodríguez, Tatiana; Mesa, María Soledad; Fernández, Eva; Arroyo-Pardo, Eduardo

2007-12-20

Population frequencies for the 9 Y-STR loci included in the "minimal haplotype" from Y-STR Haplotype Reference Database (YHRD), plus other 6 Y-STRs (DYS437, DYS438, DYS439, GATA A7.2, GATA H4 and GATA A10) were obtained for a sample of 120 males from Quito (Ecuador). One hundred and sixteen unique haplotypes were identified within the sample. Haplotype diversity (0.9994) was among the highest in comparison to other populations from Iberia and South-America. Genetic distances were calculated and our sample presented significative differences with all other samples, the lowest values being with a Guinean sample.

Detailed Investigation of the Role of Common and Low-Frequency WFS1 Variants in Type 2 Diabetes Risk

PubMed Central

Fawcett, Katherine A.; Wheeler, Eleanor; Morris, Andrew P.; Ricketts, Sally L.; Hallmans, Göran; Rolandsson, Olov; Daly, Allan; Wasson, Jon; Permutt, Alan; Hattersley, Andrew T.; Glaser, Benjamin; Franks, Paul W.; McCarthy, Mark I.; Wareham, Nicholas J.; Sandhu, Manjinder S.; Barroso, Inês

2010-01-01

OBJECTIVE Wolfram syndrome 1 (WFS1) single nucleotide polymorphisms (SNPs) are associated with risk of type 2 diabetes. In this study we aimed to refine this association and investigate the role of low-frequency WFS1 variants in type 2 diabetes risk. RESEARCH DESIGN AND METHODS For fine-mapping, we sequenced WFS1 exons, splice junctions, and conserved noncoding sequences in samples from 24 type 2 diabetic case and 68 control subjects, selected tagging SNPs, and genotyped these in 959 U.K. type 2 diabetic case and 1,386 control subjects. The same genomic regions were sequenced in samples from 1,235 type 2 diabetic case and 1,668 control subjects to compare the frequency of rarer variants between case and control subjects. RESULTS Of 31 tagging SNPs, the strongest associated was the previously untested 3′ untranslated region rs1046320 (P = 0.008); odds ratio 0.84 and P = 6.59 × 10−7 on further replication in 3,753 case and 4,198 control subjects. High correlation between rs1046320 and the original strongest SNP (rs10010131) (r2 = 0.92) meant that we could not differentiate between their effects in our samples. There was no difference in the cumulative frequency of 82 rare (minor allele frequency [MAF] <0.01) nonsynonymous variants between type 2 diabetic case and control subjects (P = 0.79). Two intermediate frequency (MAF 0.01–0.05) nonsynonymous changes also showed no statistical association with type 2 diabetes. CONCLUSIONS We identified six highly correlated SNPs that show strong and comparable associations with risk of type 2 diabetes, but further refinement of these associations will require large sample sizes (>100,000) or studies in ethnically diverse populations. Low frequency variants in WFS1 are unlikely to have a large impact on type 2 diabetes risk in white U.K. populations, highlighting the complexities of undertaking association studies with low-frequency variants identified by resequencing. PMID:20028947

Comparison of β Values in Rocks Deduced From the Elastoacoustic Effect and From 3-Wave Mixing

NASA Astrophysics Data System (ADS)

Dangelo, R.; Winkler, K. W.; Johnson, D. L.

2002-12-01

We measure the changes in the speeds of sound in Berea, wet and dry, due to the application of non-isotropic stresses (elastoacoustic effect). From these measurements we deduce values of the 3rd order elastic constants, A,B,C. We insonify these same samples, immersed in a water tank, with well-characterized acoustic signals having frequency content f1 = 1.05 MHz and f2 = 0.95 MHz. The nonlinear properties of the samples generate a difference frequency component at Δ f = 100 kHz whose amplitude we measure (3-wave mixing). We analyze the combined effects of diffraction, attenuation, and nonlinearity on these difference frequency signals by means of the KZK equation, suitably modified to account for the actual frequency dependence of the attenuation in these samples. The attenuation of the higher frequency nonlinear signals, f1+f_2, 2f1, 2f2, precludes our ability to measure them. The values of β deduced from the 3-wave mixing measurements are in the hundreds whereas the values of β implied by the values of A,B,C are in the thousands. The same experiments on lucite yield β values consistent with each other: β ≈ 6. In lucite we are easily able to measure the higher frequency nonlinear signals. The high attenuation in rocks precludes their measurement at these frequencies.

Impact of collection container material and holding times on sample integrity for mercury and methylmercury in water

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

Riscassi, Ami L; Miller, Carrie L; Brooks, Scott C

Mercury (Hg) and methylmercury (MeHg) concentrations in streamwater can vary on short timescales (hourly or less) during storm flow and on a diel cycle; the frequency and timing of sampling required to accurately characterize these dynamics may be difficult to accomplish manually. Automated sampling can assist in sample collection; however use has been limited for Hg and MeHg analysis due to stability concerns of trace concentrations during extended storage times. We examined the viability of using automated samplers with disposable low-density polyethylene (LDPE) sample bags to collect industrially contaminated streamwater for unfiltered and filtered Hg and MeHg analysis. Specifically wemore » investigated the effect of holding times ranging from hours to days on streamwater collected during baseflow and storm flow. Unfiltered and filtered Hg and MeHg concentrations decreased with increases in time prior to sample processing; holding times of 24 hours or less resulted in concentration changes (mean 11 7% different) similar to variability in duplicates collected manually during analogous field conditions (mean 7 10% different). Comparisons of samples collected with manual and automated techniques throughout a year for a wide range of stream conditions were also found to be similar to differences observed between duplicate grab samples. These results demonstrate automated sampling into LDPE bags with holding times of 24 hours or less can be effectively used to collect streamwater for Hg and MeHg analysis, and encourage the testing of these materials and methods for implementation in other aqueous systems where high-frequency sampling is warranted.« less

Infection frequency of Epstein-Barr virus in subgingival samples from patients with different periodontal status and its correlation with clinical parameters*

PubMed Central

Wu, Yan-min; Yan, Jie; Chen, Li-li; Sun, Wei-lian; Gu, Zhi-yuan

2006-01-01

Objective: To detect the infection frequencies of different genotypes of Epstein-Barr virus (EBV) in subgingival samples from chronic periodontitis (CP) patients, and to discuss the correlation between infection with EBV and clinical parameters. Methods: Nested-PCR assay was used to detect EBV-1 and EBV-2 in subgingival samples from 65 CP patients, 65 gingivitis patients and 24 periodontally healthy individuals. The amplicons were further identified by restriction fragment length polymorphism analysis (RFLP) with endonucleases Afa I and Stu I. Clinical parameters mainly included bleeding on probing (BOP), probing depth (PD), attachment loss (AL) in six sites of the dentition. Results: In CP patients, gingivitis and periodontally healthy individuals, the infection frequencies were 47.7%, 24.6% and 16.7% for EBV-1, and 15.4%, 7.7% and 0% for EBV-2, respectively. In 2 out of the 65 CP patients co-infection of EBV-1 and EBV-2 was found. The positive rate of EBV-1 in chronic periodontitis patients was higher than that in gingivitis patients (P=0.01) and periodontally healthy individuals (P=0.01). But no significant difference was shown in EBV-1 frequency between gingivitis patients and healthy individuals (P>0.05) or in EBV-2 frequency among the three groups (P>0.05). In CP patients, higher mean BOP value was found in EBV-1 or EBV-2 positive patients than that in EBV negative ones (P<0.01), but with no statistical difference in the mean PD or AL value between EBV positive and negative patients (P>0.05). After initial periodontal treatment, 12 out of the 21 EBV-1 positive CP patients did not show detectable EBV-1 in subgingival samples. Conclusion: nPCR plus RFLP analysis is a sensitive, specific and stable method to detect EBV-1 and EBV-2 in subgingival samples. Subgingival infection with EBV-1 is closely associated with chronic periodontitis. Infection of EBV in subgingival samples was correlated with BOP. PMID:17048301

The effects of sampling frequency on the climate statistics of the European Centre for Medium-Range Weather Forecasts

NASA Astrophysics Data System (ADS)

Phillips, Thomas J.; Gates, W. Lawrence; Arpe, Klaus

1992-12-01

The effects of sampling frequency on the first- and second-moment statistics of selected European Centre for Medium-Range Weather Forecasts (ECMWF) model variables are investigated in a simulation of "perpetual July" with a diurnal cycle included and with surface and atmospheric fields saved at hourly intervals. The shortest characteristic time scales (as determined by the e-folding time of lagged autocorrelation functions) are those of ground heat fluxes and temperatures, precipitation and runoff, convective processes, cloud properties, and atmospheric vertical motion, while the longest time scales are exhibited by soil temperature and moisture, surface pressure, and atmospheric specific humidity, temperature, and wind. The time scales of surface heat and momentum fluxes and of convective processes are substantially shorter over land than over oceans. An appropriate sampling frequency for each model variable is obtained by comparing the estimates of first- and second-moment statistics determined at intervals ranging from 2 to 24 hours with the "best" estimates obtained from hourly sampling. Relatively accurate estimation of first- and second-moment climate statistics (10% errors in means, 20% errors in variances) can be achieved by sampling a model variable at intervals that usually are longer than the bandwidth of its time series but that often are shorter than its characteristic time scale. For the surface variables, sampling at intervals that are nonintegral divisors of a 24-hour day yields relatively more accurate time-mean statistics because of a reduction in errors associated with aliasing of the diurnal cycle and higher-frequency harmonics. The superior estimates of first-moment statistics are accompanied by inferior estimates of the variance of the daily means due to the presence of systematic biases, but these probably can be avoided by defining a different measure of low-frequency variability. Estimates of the intradiurnal variance of accumulated precipitation and surface runoff also are strongly impacted by the length of the storage interval. In light of these results, several alternative strategies for storage of the EMWF model variables are recommended.

40 CFR 141.803 - Coliform sampling.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the disinfection and flushing frequency recommended by the aircraft water system manufacturer, when... of the aircraft water system is unrestricted. (e) Post disinfection and flushing follow-up sampling....803 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED...

40 CFR 141.803 - Coliform sampling.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the disinfection and flushing frequency recommended by the aircraft water system manufacturer, when... of the aircraft water system is unrestricted. (e) Post disinfection and flushing follow-up sampling....803 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED...

Occurrence and status of volatile organic compounds in ground water from rural, untreated, self-supplied domestic wells in the United States, 1986-99

USGS Publications Warehouse

Moran, Michael J.; Lapham, Wayne W.; Rowe, Barbara L.; Zogorski, John S.

2002-01-01

Samples of untreated ground water from 1,926 rural, self-supplied domestic wells were analyzed for volatile organic compounds (VOCs) during 1986-99. This information was used to characterize the occurrence and status of VOCs in domestic well water. The samples were either collected as part of the U.S. Geological Survey?s National Water-Quality Assessment (NAWQA) Program occurrence-assessment studies or were compiled by NAWQA from existing ambient ground-water or source-water-quality monitoring programs conducted by local, State, and other Federal agencies. Water samples were collected at the wellhead prior to treatment or storage. In most samples, 55 target VOCs were analyzed, and occurrence and status information generally was computed at an assessment level of 0.2 mg/L (microgram per liter). At least one VOC was detected in 12 percent of samples (232 samples) at an assessment level of 0.2 mg/L. This detection frequency is relatively low compared to the 26 percent detection frequency of at least one VOC in public sup-ply wells sampled by NAWQA, and the difference may be due, in part, to the higher pumping rates, pumping stress factors, and larger contributing areas of public supply wells. Samples with detections of at least one VOC were collected from wells located in 31 of 39 States. Solvents were the most frequently detected VOC group with detections in 4.6 percent of samples (89 samples) at an assessment level of 0.2 mg/L. The geographic distribution of detections of some VOC groups, such as fumigants and oxygenates, relates to the use pattern of com-pounds in that group. With the exception of com-pounds used in organic synthesis, detection frequencies of VOCs by group are proportional to the average half-life of compounds in the group. When the organic synthesis group is excluded from the analysis, a good correlation exists between the detection frequency of VOCs by group and average half-life of compounds in the group. Individually, VOCs were not commonly detected at an assessment level of 0.2 mg/L, with the seven most frequently detected VOCs found in only 1 to 5 percent of samples. Mixtures (two or more compounds) were a common mode of occurrence for VOCs when no assessment level was applied, and mixtures occurred in one-half of all samples that contained at least one VOC. Only 1.4 percent of samples (27 samples) had one or more VOC concentrations that exceeded a federally established drinking-water standard or health criterion. Only 0.1 percent of samples (2 samples) had one or more VOC concentrations that exceeded a taste/odor threshold. Potential point sources of VOCs near domestic wells are numerous. Leaks from under-ground storage tanks and aboveground storage tanks that hold gasoline, diesel fuel, or heating oil have the potential to be major point sources of contaminants to domestic wells. Shock chlorination may be a source of trichloromethane and other trihalomethanes in some domestic wells. Septic systems are believed to be an important source of contaminants to domestic wells, but extensive research on this subject does not exist. VOCs frequently are ingredients in household products such as cleansers and insecticides, and some VOCs have been found in septic systems.

Reduction of display artifacts by random sampling

NASA Technical Reports Server (NTRS)

Ahumada, A. J., Jr.; Nagel, D. C.; Watson, A. B.; Yellott, J. I., Jr.

1983-01-01

The application of random-sampling techniques to remove visible artifacts (such as flicker, moire patterns, and paradoxical motion) introduced in TV-type displays by discrete sequential scanning is discussed and demonstrated. Sequential-scanning artifacts are described; the window of visibility defined in spatiotemporal frequency space by Watson and Ahumada (1982 and 1983) and Watson et al. (1983) is explained; the basic principles of random sampling are reviewed and illustrated by the case of the human retina; and it is proposed that the sampling artifacts can be replaced by random noise, which can then be shifted to frequency-space regions outside the window of visibility. Vertical sequential, single-random-sequence, and continuously renewed random-sequence plotting displays generating 128 points at update rates up to 130 Hz are applied to images of stationary and moving lines, and best results are obtained with the single random sequence for the stationary lines and with the renewed random sequence for the moving lines.

Improving the sampling efficiency of Monte Carlo molecular simulations: an evolutionary approach

NASA Astrophysics Data System (ADS)

Leblanc, Benoit; Braunschweig, Bertrand; Toulhoat, Hervé; Lutton, Evelyne

We present a new approach in order to improve the convergence of Monte Carlo (MC) simulations of molecular systems belonging to complex energetic landscapes: the problem is redefined in terms of the dynamic allocation of MC move frequencies depending on their past efficiency, measured with respect to a relevant sampling criterion. We introduce various empirical criteria with the aim of accounting for the proper convergence in phase space sampling. The dynamic allocation is performed over parallel simulations by means of a new evolutionary algorithm involving 'immortal' individuals. The method is bench marked with respect to conventional procedures on a model for melt linear polyethylene. We record significant improvement in sampling efficiencies, thus in computational load, while the optimal sets of move frequencies are liable to allow interesting physical insights into the particular systems simulated. This last aspect should provide a new tool for designing more efficient new MC moves.

Advanced Non-Destructive Assessment Technology to Determine the Aging of Silicon Containing Materials for Generation IV Nuclear Reactors

NASA Astrophysics Data System (ADS)

Koenig, T. W.; Olson, D. L.; Mishra, B.; King, J. C.; Fletcher, J.; Gerstenberger, L.; Lawrence, S.; Martin, A.; Mejia, C.; Meyer, M. K.; Kennedy, R.; Hu, L.; Kohse, G.; Terry, J.

2011-06-01

To create an in-situ, real-time method of monitoring neutron damage within a nuclear reactor core, irradiated silicon carbide samples are examined to correlate measurable variations in the material properties with neutron fluence levels experienced by the silicon carbide (SiC) during the irradiation process. The reaction by which phosphorus doping via thermal neutrons occurs in the silicon carbide samples is known to increase electron carrier density. A number of techniques are used to probe the properties of the SiC, including ultrasonic and Hall coefficient measurements, as well as high frequency impedance analysis. Gamma spectroscopy is also used to examine residual radioactivity resulting from irradiation activation of elements in the samples. Hall coefficient measurements produce the expected trend of increasing carrier concentration with higher fluence levels, while high frequency impedance analysis shows an increase in sample impedance with increasing fluence.

Airborne measurements of sulfur dioxide, dimethyl sulfide, carbon disulfide, and carbonyl sulfide by isotope dilution gas chromatography/mass spectrometry

NASA Technical Reports Server (NTRS)

Bandy, Alan R.; Thornton, Donald C.; Driedger, Arthur R., III

1993-01-01

A gas chromatograph/mass spectrometer is described for determining atmospheric sulfur dioxide, carbon disulfide, dimethyl sulfide, and carbonyl sulfide from aircraft and ship platforms. Isotopically labelled variants of each analyte were used as internal standards to achieve high precision. The lower limit of detection for each species for an integration time of 3 min was 1 pptv for sulfur dioxide and dimethyl sulfide and 0.2 pptv for carbon disulfide and carbonyl sulfide. All four species were simultaneously determined with a sample frequency of one sample per 6 min or greater. When only one or two species were determined, a frequency of one sample per 4 min was achieved. Because a calibration is included in each sample, no separate calibration sequence was needed. Instrument warmup was only a few minutes. The instrument was very robust in field deployments, requiring little maintenance.

Sampling and Reconstruction of the Pupil and Electric Field for Phase Retrieval

NASA Technical Reports Server (NTRS)

Dean, Bruce; Smith, Jeffrey; Aronstein, David

2012-01-01

This technology is based on sampling considerations for a band-limited function, which has application to optical estimation generally, and to phase retrieval specifically. The analysis begins with the observation that the Fourier transform of an optical aperture function (pupil) can be implemented with minimal aliasing for Q values down to Q = 1. The sampling ratio, Q, is defined as the ratio of the sampling frequency to the band-limited cut-off frequency. The analytical results are given using a 1-d aperture function, and with the electric field defined by the band-limited sinc(x) function. Perfect reconstruction of the Fourier transform (electric field) is derived using the Whittaker-Shannon sampling theorem for 1

How much is enough? Examining frequency criteria for NSSI disorder in adolescent inpatients.

PubMed

Muehlenkamp, Jennifer J; Brausch, Amy M; Washburn, Jason J

2017-06-01

To empirically evaluate the diagnostic relevance of the proposed Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5 ; APA, 2013) Criterion-A frequency threshold for nonsuicidal self-injury (NSSI) disorder. Archival, de-identified, self-reported clinical assessment data from 746 adolescent psychiatric patients (Mage = 14.97; 88% female; 76% White) were used. The sample was randomly split into 2 unique samples for data analyses. Measures included assessments of NSSI, proposed DSM-5 NSSI-disorder criteria, psychopathology, dysfunction, distress, functional impairment, and suicidality. Discriminant-function analyses run with Sample A identified a significant differentiation of groups based on a frequency of NSSI at 25 or more days in the past year, Λ = .814, χ2(54) = 72.59, p < .05, canonical R2 = .36. This cutoff was replicated in the second sample. All patients were coded into 1 of 3 empirically derived NSSI-frequency cutoff groups: high (>25 days), moderate (5-24 days), and low (1-4 days) and compared. The high-NSSI group scored higher on most NSSI features, including DSM-5 -proposed Criterion-B and -C symptoms, depression, psychotic symptoms, substance abuse, borderline personality-disorder features, suicidal ideation, and suicide plans, than the moderate- and low-NSSI groups, who did not differ from each other on many of the variables. The currently proposed DSM-5 Criterion-A frequency threshold for NSSI disorder lacks validity and clinical utility. The field needs to consider raising the frequency threshold to ensure that a meaningful and valid set of diagnostic criteria are established, and to avoid overpathologizing individuals who infrequently engage in NSSI. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Levels of select organophosphates in human colostrum and mature milk samples in rural region of Faizabad district, Uttar Pradesh, India.

PubMed

Srivastava, S; Narvi, S S; Prasad, S C

2011-10-01

Human colostrum and mature milk samples from rural mothers were separately screened for organophosphate pesticides (OPPs). The samples were assessed for the pollution load they are transmitting to the nursing infant to determine potential toxicity. The role of colostrum for toxicity monitoring was assessed in comparison to mature milk as it is the very first infant food. The pesticides were quantified using a Gas Chromatograph equipped with Electron Capture Detector (GC-ECD) and the results were further validated on GC linked with Mass Spectrophotometer (GC-MS) and Fourier transform infrared (FTIR). A total of 33 samples were analyzed out of 40 samples collected. These samples were from 33 mothers. Out of these, 25 were colostrum samples and 8 were mature milk samples. Frequency percentage (N%) of organophosphates analyzed was highest for ethion (23.1% or 6/26) in colostrum and chlorpyrifos (50% or 4/8) in mature milk samples. Frequency percentage in colostrum was 19.2% (5/26) for chlorpyrifos and 3.8% (1/26) for dimethoate; 25.0% (2/8) mature milk samples carried dimethoate and 12.5% (1/8) carried ethion. Mean OPPs in colostrum: dimethoate (85.888 ng/g fat) > ethion (48.000 ng/g fat) > chlorpyrifos (4.003 ng/g fat); and mature milk: ethion (744.925 ng/g fat) > chlorpyrifos (37.274 ng/g fat) > dimethoate (26.752 ng/g fat). MS data revealed the presence of methyl parathion, which was not quantitated. None of the samples exceeded acceptable daily intake standards set by Joint Meeting on Pesticide Residues (JMPR). The study will pave way for further analysis on pesticide toxicology.

Free-running waveform characterization using a delay-time tunable laser based delay-line-free electro-optic sampling oscilloscope

NASA Astrophysics Data System (ADS)

Lin, Gong-Ru

2002-12-01

We develop a delay-line-free and frequency traceable electro-optic sampling oscilloscope by use of a digital phase-locked loop phase shifter (PLL-PS) controlled delay-time-tunable gain-switched laser diode (GSLD). The home-made voltage-controllable PLL-PS exhibits a linear transfer function with ultra-wide phase shifting range of ±350° and tuning error of <±5%, which benefits the advantages of frequency tracking to free-running signals with suppressed timing-jitter. The maximum delay-time of PLL-PS controlled GSLD is up to 1.95 periods by changing the controlling voltage ( VREF) from -3.5 to 3.5 V, which corresponds to 3.9 ns at repetition frequency of 500 MHz. The tuning responsivity and resolution are about 0.56 ns/V and 0.15˜0.2 ps, respectively. The maximum delay-time switching bandwidth of 100 Hz is determined under the control of a saw-tooth modulated VREF function. The waveform sampling of microwave PECL signals generated from a free-running digital frequency divider is performed with acceptable measuring deviation.

Adjustable Nyquist-rate System for Single-Bit Sigma-Delta ADC with Alternative FIR Architecture

NASA Astrophysics Data System (ADS)

Frick, Vincent; Dadouche, Foudil; Berviller, Hervé

2016-09-01

This paper presents a new smart and compact system dedicated to control the output sampling frequency of an analogue-to-digital converters (ADC) based on single-bit sigma-delta (ΣΔ) modulator. This system dramatically improves the spectral analysis capabilities of power network analysers (power meters) by adjusting the ADC's sampling frequency to the input signal's fundamental frequency with a few parts per million accuracy. The trade-off between straightforwardness and performance that motivated the choice of the ADC's architecture are preliminary discussed. It particularly comes along with design considerations of an ultra-steep direct-form FIR that is optimised in terms of size and operating speed. Thanks to compact standard VHDL language description, the architecture of the proposed system is particularly suitable for application-specific integrated circuit (ASIC) implementation-oriented low-power and low-cost power meter applications. Field programmable gate array (FPGA) prototyping and experimental results validate the adjustable sampling frequency concept. They also show that the system can perform better in terms of implementation and power capabilities compared to dedicated IP resources.

Anomalies in the low frequency vibrational density of states for a polymer with intrinsic microporosity - the Boson peak of PIM-1.

PubMed

Zorn, Reiner; Yin, Huajie; Lohstroh, Wiebke; Harrison, Wayne; Budd, Peter M; Pauw, Brian R; Böhning, Martin; Schönhals, Andreas

2018-01-17

Polymers with intrinsic microporosity are promising candidates for the active separation layer in gas separation membranes. Here, the vibrational density of states (VDOS) for PIM-1, the prototypical polymer with intrinsic microporosity, is investigated by means of inelastic neutron scattering. The results are compared to data measured for a more conventional high-performance polyimide used in gas separation membranes (Matrimid). The measured data show the characteristic low frequency excess contribution to VDOS above the Debye sound wave level, generally known as the Boson peak in glass-forming materials. In comparison to the Boson peak of Matrimid, that of PIM-1 is shifted to lower frequencies. This shift is discussed considering the microporous, sponge-like structure of PIM-1 as providing a higher compressibility at the molecular scale than for conventional polymers. For an annealed PIM-1 sample, the Boson peak shifts to higher frequencies in comparison to the un-annealed sample. These changes in the VDOS of the annealed PIM-1 sample are related to changes in the microporous structure as confirmed by X-ray scattering.

Scaled nonuniform Fourier transform for image reconstruction in swept source optical coherence tomography

NASA Astrophysics Data System (ADS)

Mezgebo, Biniyam; Nagib, Karim; Fernando, Namal; Kordi, Behzad; Sherif, Sherif

2018-02-01

Swept Source optical coherence tomography (SS-OCT) is an important imaging modality for both medical and industrial diagnostic applications. A cross-sectional SS-OCT image is obtained by applying an inverse discrete Fourier transform (DFT) to axial interferograms measured in the frequency domain (k-space). This inverse DFT is typically implemented as a fast Fourier transform (FFT) that requires the data samples to be equidistant in k-space. As the frequency of light produced by a typical wavelength-swept laser is nonlinear in time, the recorded interferogram samples will not be uniformly spaced in k-space. Many image reconstruction methods have been proposed to overcome this problem. Most such methods rely on oversampling the measured interferogram then use either hardware, e.g., Mach-Zhender interferometer as a frequency clock module, or software, e.g., interpolation in k-space, to obtain equally spaced samples that are suitable for the FFT. To overcome the problem of nonuniform sampling in k-space without any need for interferogram oversampling, an earlier method demonstrated the use of the nonuniform discrete Fourier transform (NDFT) for image reconstruction in SS-OCT. In this paper, we present a more accurate method for SS-OCT image reconstruction from nonuniform samples in k-space using a scaled nonuniform Fourier transform. The result is demonstrated using SS-OCT images of Axolotl salamander eggs.

Electro-Optic Characterisation of Extremely Wide Bandwidth Electrical Signals

DTIC Science & Technology

1993-02-01

In this report an ultrafast electro - optic sampling system suitable for applications such as device characterisation is described. The aperture time of the sampler is calculated to be about 290 fs, implying an attainable device bandwidth in excess of 300 GHz. The sampler was characterised using a test pulse with approximately 12 GHz of frequency content, and the results compared to those obtained from an 18 GHz digital sampling oscilloscope. Signal Processing, Bandwidth, Frequencies, Oscilloscopes.

Optical and Radio Frequency Refractivity Fluctuations from High Resolution Point Sensors: Sea Breezes and Other Observations

DTIC Science & Technology

2007-03-01

velocity and direction along with vertical velocities are derived from the measured time of flight for the ultrasonic signals (manufacture’s...data set. To prevent aliasing a wave must be sample at least twice per period so the Nyquist frequency is sn ff 2 = . 3. Sampling Requirements...an order of magnitude or more. To refine models or conduct climatologically studies for Cn2 requires direct measurements to identify the underlying

New Techniques in Time-Frequency Analysis: Adaptive Band, Ultra-Wide Band and Multi-Rate Signal Processing

DTIC Science & Technology

2016-03-02

Nyquist tiles and sampling groups in Euclidean geometry, and discussed the extension of these concepts to hyperbolic and spherical geometry and...hyperbolic or spherical spaces. We look to develop a structure for the tiling of frequency spaces in both Euclidean and non-Euclidean domains. In particular...we establish Nyquist tiles and sampling groups in Euclidean geometry, and discuss the extension of these concepts to hyperbolic and spherical geometry

Single exosome detection in serum using microtoroid optical resonators (Conference Presentation)

NASA Astrophysics Data System (ADS)

Su, Judith

2016-03-01

Recently exosomes have attracted interest due to their potential as cancer biomarkers. We report the real time, label-free sensing of single exosomes in serum using microtoroid optical resonators. We use this approach to assay the progression of tumors implanted in mice by specifically detecting low concentrations of tumor-derived exosomes. Our approach measures the adsorption of individual exosomes onto a functionalized silica microtoroid by tracking changes in the optical resonant frequency of the microtoroid. When exosomes land on the microtoroid, they perturb its refractive index in the evanescent field and thus shift its resonance frequency. Through digital frequency locking, we are able to rapidly track these shifts with accuracies of better than 10 attometers (one part in 10^11). Samples taken from tumor-implanted mice from later weeks generated larger frequency shifts than those from earlier weeks. Control samples taken from a mouse with no tumor generated no such increase in signal between subsequent weeks. Analysis of shifts from tumor-implanted mouse samples show a distribution of unitary steps, with the maximum step having a height of ~1.2 fm, corresponding to an exosome size of 44 ± 4.8 nm. This size range corresponds to that found by performing nanoparticle tracking analysis on the same samples. Our results demonstrate development towards a minimally-invasive tumor "biopsy" that eliminates the need to find and access a tumor.

Kinematic Clues to OB Field Star Origins: Radial Velocities, Runaways, and Binaries

NASA Astrophysics Data System (ADS)

Januszewski, Helen; Castro, Norberto; Oey, Sally; Becker, Juliette; Kratter, Kaitlin M.; Mateo, Mario; Simón-Díaz, Sergio; Bjorkman, Jon E.; Bjorkman, Karen; Sigut, Aaron; Smullen, Rachel; M2FS Team

2018-01-01

Field OB stars are a crucial probe of star formation in extreme conditions. Properties of massive stars formed in relative isolation can distinguish between competing star formation theories, while the statistics of runaway stars allow an indirect test of the densest conditions in clusters. To address these questions, we have obtained multi-epoch, spectroscopic observations for a spatially complete sample of 48 OB field stars in the SMC Wing with the IMACS and M2FS multi-object spectrographs at the Magellan Telescopes. The observations span 3-6 epochs per star, with sampling frequency ranging from one day to about one year. From these spectra, we have calculated the radial velocities (RVs) and, in particular, the systemic velocities for binaries. Thus, we present the intrinsic RV distribution largely uncontaminated by binary motions. We estimate the runaway frequency, corresponding to the high velocity stars in our sample, and we also constrain the binary frequency. The binary frequency and fitted orbital parameters also place important constraints on star formation theories, as these properties drive the process of runaway ejection in clusters, and we discuss these properties as derived from our sample. This unique kinematic analysis of a high mass field star population thus provides a new look at the processes governing formation and interaction of stars in environments at extreme densities, from isolation to dense clusters.

A Multi-Channel Method for Retrieving Surface Temperature for High-Emissivity Surfaces from Hyperspectral Thermal Infrared Images

PubMed Central

Zhong, Xinke; Labed, Jelila; Zhou, Guoqing; Shao, Kun; Li, Zhao-Liang

2015-01-01

The surface temperature (ST) of high-emissivity surfaces is an important parameter in climate systems. The empirical methods for retrieving ST for high-emissivity surfaces from hyperspectral thermal infrared (HypTIR) images require spectrally continuous channel data. This paper aims to develop a multi-channel method for retrieving ST for high-emissivity surfaces from space-borne HypTIR data. With an assumption of land surface emissivity (LSE) of 1, ST is proposed as a function of 10 brightness temperatures measured at the top of atmosphere by a radiometer having a spectral interval of 800–1200 cm−1 and a spectral sampling frequency of 0.25 cm−1. We have analyzed the sensitivity of the proposed method to spectral sampling frequency and instrumental noise, and evaluated the proposed method using satellite data. The results indicated that the parameters in the developed function are dependent on the spectral sampling frequency and that ST of high-emissivity surfaces can be accurately retrieved by the proposed method if appropriate values are used for each spectral sampling frequency. The results also showed that the accuracy of the retrieved ST is of the order of magnitude of the instrumental noise and that the root mean square error (RMSE) of the ST retrieved from satellite data is 0.43 K in comparison with the AVHRR SST product. PMID:26061199

High-frequency DOC and nitrate measurements provide new insights into their export and their relationships to rainfall-runoff processes

NASA Astrophysics Data System (ADS)

Schwab, Michael; Klaus, Julian; Pfister, Laurent; Weiler, Markus

2015-04-01

Over the past decades, stream sampling protocols for environmental tracers were often limited by logistical and technological constraints. Long-term sampling programs would typically rely on weekly sampling campaigns, while high-frequency sampling would remain restricted to a few days or hours at best. We stipulate that the currently predominant sampling protocols are too coarse to capture and understand the full amplitude of rainfall-runoff processes and its relation to water quality fluctuations. Weekly sampling protocols are not suited to get insights into the hydrological system during high flow conditions. Likewise, high frequency measurements of a few isolated events do not allow grasping inter-event variability in contributions and processes. Our working hypothesis is based on the potential of a new generation of field-deployable instruments for measuring environmental tracers at high temporal frequencies over an extended period. With this new generation of instruments we expect to gain new insights into rainfall-runoff dynamics, both at intra- and inter-event scales. Here, we present the results of one year of DOC and nitrate measurements with the field deployable UV-Vis spectrometer spectro::lyser (scan Messtechnik GmbH). The instrument measures the absorption spectrum from 220 to 720 nm in situ and at high frequencies and derives DOC and nitrate concentrations. The measurements were carried out at 15 minutes intervals in the Weierbach catchment (0.47 km2) in Luxemburg. This fully forested catchment is characterized by cambisol soils and fractured schist as underlying bedrock. The time series of DOC and nitrate give insights into the high frequency dynamics of stream water. Peaks in DOC concentrations are closely linked to discharge peaks that occur during or right after a rainfall event. Those first discharge peaks can be linked to fast near surface runoff processes and are responsible for a remarkable amount of DOC export. A special characterisation of the Weierbach catchment are the delayed second peaks a few days after the rainfall event. Nitrate concentrations are following this second peak. We assume that this delayed response is going back to subsurface or upper groundwater flows, with nitrate enriched water. On an inter-event scale during low flow / base flow conditions, we observe interesting diurnal patterns of both DOC and nitrate concentrations. Overall, the long-term high-frequency measurements of DOC and nitrate provide us the opportunity to separate different rainfall-runoff processes and link the amount of DOC and nitrate export to them to quantify the overall relevance of the different processes.

Using high-frequency water quality data to assess sampling strategies for the EU Water Framework Directive

NASA Astrophysics Data System (ADS)

Skeffington, R. A.; Halliday, S. J.; Wade, A. J.; Bowes, M. J.; Loewenthal, M.

2015-05-01

The EU Water Framework Directive (WFD) requires that the ecological and chemical status of water bodies in Europe should be assessed, and action taken where possible to ensure that at least "good" quality is attained in each case by 2015. This paper is concerned with the accuracy and precision with which chemical status in rivers can be measured given certain sampling strategies, and how this can be improved. High-frequency (hourly) chemical data from four rivers in southern England were subsampled to simulate different sampling strategies for four parameters used for WFD classification: dissolved phosphorus, dissolved oxygen, pH and water temperature. These data sub-sets were then used to calculate the WFD classification for each site. Monthly sampling was less precise than weekly sampling, but the effect on WFD classification depended on the closeness of the range of concentrations to the class boundaries. In some cases, monthly sampling for a year could result in the same water body being assigned to three or four of the WFD classes with 95% confidence, due to random sampling effects, whereas with weekly sampling this was one or two classes for the same cases. In the most extreme case, the same water body could have been assigned to any of the five WFD quality classes. Weekly sampling considerably reduces the uncertainties compared to monthly sampling. The width of the weekly sampled confidence intervals was about 33% that of the monthly for P species and pH, about 50% for dissolved oxygen, and about 67% for water temperature. For water temperature, which is assessed as the 98th percentile in the UK, monthly sampling biases the mean downwards by about 1 °C compared to the true value, due to problems of assessing high percentiles with limited data. Low-frequency measurements will generally be unsuitable for assessing standards expressed as high percentiles. Confining sampling to the working week compared to all 7 days made little difference, but a modest improvement in precision could be obtained by sampling at the same time of day within a 3 h time window, and this is recommended. For parameters with a strong diel variation, such as dissolved oxygen, the value obtained, and thus possibly the WFD classification, can depend markedly on when in the cycle the sample was taken. Specifying this in the sampling regime would be a straightforward way to improve precision, but there needs to be agreement about how best to characterise risk in different types of river. These results suggest that in some cases it will be difficult to assign accurate WFD chemical classes or to detect likely trends using current sampling regimes, even for these largely groundwater-fed rivers. A more critical approach to sampling is needed to ensure that management actions are appropriate and supported by data.

New sample cell configuration for wide-frequency dielectric spectroscopy: DC to radio frequencies.

PubMed

Nakanishi, Masahiro; Sasaki, Yasutaka; Nozaki, Ryusuke

2010-12-01

A new configuration for the sample cell to be used in broadband dielectric spectroscopy is presented. A coaxial structure with a parallel plate capacitor (outward parallel plate cell: OPPC) has made it possible to extend the frequency range significantly in comparison with the frequency range of the conventional configuration. In the proposed configuration, stray inductance is significantly decreased; consequently, the upper bound of the frequency range is improved by two orders of magnitude from the upper limit of conventional parallel plate capacitor (1 MHz). Furthermore, the value of capacitance is kept high by using a parallel plate configuration. Therefore, the precision of the capacitance measurement in the lower frequency range remains sufficiently high. Finally, OPPC can cover a wide frequency range (100 Hz-1 GHz) with an appropriate admittance measuring apparatus such as an impedance or network analyzer. The OPPC and the conventional dielectric cell are compared by examining the frequency dependence of the complex permittivity for several polar liquids and polymeric films.

Accurate EPR radiosensitivity calibration using small sample masses

NASA Astrophysics Data System (ADS)

Hayes, R. B.; Haskell, E. H.; Barrus, J. K.; Kenner, G. H.; Romanyukha, A. A.

2000-03-01

We demonstrate a procedure in retrospective EPR dosimetry which allows for virtually nondestructive sample evaluation in terms of sample irradiations. For this procedure to work, it is shown that corrections must be made for cavity response characteristics when using variable mass samples. Likewise, methods are employed to correct for empty tube signals, sample anisotropy and frequency drift while considering the effects of dose distribution optimization. A demonstration of the method's utility is given by comparing sample portions evaluated using both the described methodology and standard full sample additive dose techniques. The samples used in this study are tooth enamel from teeth removed during routine dental care. We show that by making all the recommended corrections, very small masses can be both accurately measured and correlated with measurements of other samples. Some issues relating to dose distribution optimization are also addressed.

Wiener-matrix image restoration beyond the sampling passband

NASA Technical Reports Server (NTRS)

Rahman, Zia-Ur; Alter-Gartenberg, Rachel; Fales, Carl L.; Huck, Friedrich O.

1991-01-01

A finer-than-sampling-lattice resolution image can be obtained using multiresponse image gathering and Wiener-matrix restoration. The multiresponse image gathering weighs the within-passband and aliased signal components differently, allowing the Wiener-matrix restoration filter to unscramble these signal components and restore spatial frequencies beyond the sampling passband of the photodetector array. A multiresponse images can be reassembled into a single minimum mean square error image with a resolution that is sq rt A times finer than the photodetector-array sampling lattice.

Navigation Using Orthogonal Frequency Division Multiplexed Signals of Opportunity

DTIC Science & Technology

2007-09-01

transmits a 32,767 bit pseudo -random “short” code that repeats 37.5 times per second. Since the pseudo -random bit pattern and modulation scheme are... correlation process takes two “ sample windows,” both of which are ν = 16 samples wide and are spaced N = 64 samples apart, and compares them. When the...technique in (3.4) is a necessary step in order to get a more accurate estimate of the sample shift from the symbol boundary correlator in (3.1). Figure

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

LaFreniere, Lorraine M.

In March 2009, the CCC/USDA developed a plan for annual monitoring of the groundwater and surface water (Argonne 2009). Under this plan, approved by the KDHE (2009), monitoring wells are sampled by using the low-flow procedure (Puls and Barcelona 1996; Yeskis and Zavala 2002), and surface water samples are collected at five locations along the intermittent creek. Vegetation sampling is conducted as a secondary indicator of plume migration. As of 2015, the frequency of surface water sampling has been decreased to once yearly, per the approval of the KDHE (2015).

Can we estimate molluscan abundance and biomass on the continental shelf?

NASA Astrophysics Data System (ADS)

Powell, Eric N.; Mann, Roger; Ashton-Alcox, Kathryn A.; Kuykendall, Kelsey M.; Chase Long, M.

2017-11-01

Few empirical studies have focused on the effect of sample density on the estimate of abundance of the dominant carbonate-producing fauna of the continental shelf. Here, we present such a study and consider the implications of suboptimal sampling design on estimates of abundance and size-frequency distribution. We focus on a principal carbonate producer of the U.S. Atlantic continental shelf, the Atlantic surfclam, Spisula solidissima. To evaluate the degree to which the results are typical, we analyze a dataset for the principal carbonate producer of Mid-Atlantic estuaries, the Eastern oyster Crassostrea virginica, obtained from Delaware Bay. These two species occupy different habitats and display different lifestyles, yet demonstrate similar challenges to survey design and similar trends with sampling density. The median of a series of simulated survey mean abundances, the central tendency obtained over a large number of surveys of the same area, always underestimated true abundance at low sample densities. More dramatic were the trends in the probability of a biased outcome. As sample density declined, the probability of a survey availability event, defined as a survey yielding indices >125% or <75% of the true population abundance, increased and that increase was disproportionately biased towards underestimates. For these cases where a single sample accessed about 0.001-0.004% of the domain, 8-15 random samples were required to reduce the probability of a survey availability event below 40%. The problem of differential bias, in which the probabilities of a biased-high and a biased-low survey index were distinctly unequal, was resolved with fewer samples than the problem of overall bias. These trends suggest that the influence of sampling density on survey design comes with a series of incremental challenges. At woefully inadequate sampling density, the probability of a biased-low survey index will substantially exceed the probability of a biased-high index. The survey time series on the average will return an estimate of the stock that underestimates true stock abundance. If sampling intensity is increased, the frequency of biased indices balances between high and low values. Incrementing sample number from this point steadily reduces the likelihood of a biased survey; however, the number of samples necessary to drive the probability of survey availability events to a preferred level of infrequency may be daunting. Moreover, certain size classes will be disproportionately susceptible to such events and the impact on size frequency will be species specific, depending on the relative dispersion of the size classes.

Devices for SRF material characterization

DOE PAGES

Goudket, Philippe; Xiao, B.; Junginger, T.

2016-10-07

The surface resistance Rs of superconducting materials can be obtained by measuring the quality factor of an elliptical cavity excited in a transverse magnetic mode (TM010). The value obtained has however to be taken as averaged over the whole surface. A more convenient way to obtain Rs, especially of materials which are not yet technologically ready for cavity production, is to measure small samples instead. These can be easily man ufactured at low cost, duplicated and placed in film deposition and surface analytical tools. A commonly used design for a device to measure Rs consists of a cylindrical cavity excitedmore » in a transverse electric (TE110) mode with the sample under test serving as one replaceable endplate. Such a cavity has two drawbacks. For reasonably small samples the resonant frequency will be larger than frequencies of interest concerning SRF application and it requires a reference sample of known Rs. In this article we review several devices which have been designed to overcome these limitations, reaching sub - nΩ resolution in some cases. Some of these devices also comprise a parameter space in frequency and temperature which is inaccessible to standard cavity tests, making them ideal tools to test theoretical surface resistance models.« less

Devices for SRF material characterization

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

Goudket, Philippe; Xiao, B.; Junginger, T.

The surface resistance Rs of superconducting materials can be obtained by measuring the quality factor of an elliptical cavity excited in a transverse magnetic mode (TM010). The value obtained has however to be taken as averaged over the whole surface. A more convenient way to obtain Rs, especially of materials which are not yet technologically ready for cavity production, is to measure small samples instead. These can be easily man ufactured at low cost, duplicated and placed in film deposition and surface analytical tools. A commonly used design for a device to measure Rs consists of a cylindrical cavity excitedmore » in a transverse electric (TE110) mode with the sample under test serving as one replaceable endplate. Such a cavity has two drawbacks. For reasonably small samples the resonant frequency will be larger than frequencies of interest concerning SRF application and it requires a reference sample of known Rs. In this article we review several devices which have been designed to overcome these limitations, reaching sub - nΩ resolution in some cases. Some of these devices also comprise a parameter space in frequency and temperature which is inaccessible to standard cavity tests, making them ideal tools to test theoretical surface resistance models.« less

Dielectric characteristics of Mn-doped LaTiO3+δ ceramics

NASA Astrophysics Data System (ADS)

Chen, Yan; Cui, Yimin

A series of ceramic composites of Mn-doped La1- x MnxTiO3+ δ and LaMnxTi1- x O3+ δ (x = 0.1, 0.2) were synthesized by conventional solid-state reaction method. The low-frequency complex dielectric properties of the composites were investigated as functions of temperature (77 K <= T <= 360 K) and frequency (100 Hz <= f <= 1 MHz), respectively. The dielectric constant of A-site doped samples is higher than that of B-site doped samples. The loss tangent of low doped samples is much less than that of high doped samples. The A-site doped composites exhibit intrinsic dielectric response with a dielectric constant of 40 in the temperature below 250 K. Interestingly, the dielectric constants of B-site doped ceramics increase slightly in the temperature range from 77 to 360 K. And it is clearly observed that extraordinarily high dielectric loss tangent ( 6) appear at low frequency (100 Hz) in LaMn0.2Ti0.8O3+ δ , which is 8 times larger than that of LaMn0.1Ti0.9O3+ δ , which indicates that the doped content can affect the intrinsic dielectric characteristics significantly.

Dependence of flux-flow critical frequencies and generalized bundle sizes on distance of fluxoid traversal and fluxoid length in foil samples

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

Thompson, J.D.; Joiner, W.C.H.

1979-10-01

Flux-flow noise power spectra taken on Pb/sub 80/In/sub 20/ foils as a function of the orientation of the magnetic field with respect to the sample surfaces are used to study changes in frequencies and bundle sizes as distances of fluxoid traversal and fluxoid lengths change. The results obtained for the frequency dependence of the noise spectra are entirely consistent with our model for flux motion interrupted by pinning centers, provided one makes the reasonable assumption that the distance between pinning centers which a fluxoid may encounter scales inversely with the fluxoid length. The importance of pinning centers in determining themore » noise characteristics is also demonstrated by the way in which subpulse distributions and generalized bundle sizes are altered by changes in the metallurgical structure of the sample. In unannealed samples the dependence of bundle size on magnetic field orientation is controlled by a structural anisotropy, and we find a correlation between large bundle size and the absence of short subpulse times. Annealing removes this anisotropy, and we find a stronger angular variation of bundle size than would be expected using present simplified models.« less

A versatile rotary-stage high frequency probe station for studying magnetic films and devices

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

He, Shikun; Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371; Meng, Zhaoliang

We present a rotary-stage microwave probe station suitable for magnetic films and spintronic devices. Two stages, one for field rotation from parallel to perpendicular to the sample plane (out-of-plane) and the other intended for field rotation within the sample plane (in-plane) have been designed. The sample probes and micro-positioners are rotated simultaneously with the stages, which allows the field orientation to cover θ from 0{sup ∘} to 90{sup ∘} and φ from 0{sup ∘} to 360{sup ∘}. θ and φ being the angle between the direction of current flow and field in a out-of-plane and an in-plane rotation, respectively. Themore » operation frequency is up to 40 GHz and the magnetic field up to 1 T. The sample holder vision system and probe assembly are compactly designed for the probes to land on a wafer with diameter up to 3 cm. Using homemade multi-pin probes and commercially available high frequency probes, several applications including 4-probe DC measurements, the determination of domain wall velocity, and spin transfer torque ferromagnetic resonance are demonstrated.« less

Method and apparatus for identifying conductive objects by monitoring the true resistive component of impedance change in a coil system caused by the object

DOEpatents

Gregory, William D.; Capots, Larry H.; George, James P.; Janik, Richard

1981-01-01

The type of conductor, its property, and if a metal, its type and cross-sectional area can be obtained from measurements made at different frequencies for the amount of unbalance created in a previously balanced stable coil detection system. The true resistive component is accurately measured and thus reflects only the voltage loss attributable to eddy currents caused by introduction of the test sample to the coil system. This voltage divided by corresponding applied frequency gives a curve which peaks at a frequency dependent upon type of conductor. For a metal this peak frequency is proportional to the samples resistivity divided by its cross-sectional area.

Occurrence of tetracycline resistance genes in aquaculture facilities with varying use of oxytetracycline

PubMed Central

Seyfried, Erin E.; Newton, Ryan J.; Rubert, Kennedy F.; Pedersen, Joel A.; McMahon, Katherine D.

2014-01-01

The contribution of human activities to environmental reservoirs of antibiotic resistance is poorly understood. The purpose of this study was to determine if oxytetracycline (OTC) use in aquaculture facilities increased the detection frequency (i.e. prevalence) of tetracycline resistance genes relative to facilities with no recent OTC treatment. We used PCR to screen water and sediment from four non-commercial fish farms in northwestern Wisconsin for the presence of ten tetracycline resistance determinants (tetR): tet(A), tet(B), tet(D), tet(E), tet(G), tet(M), tet(O), tet(Q), tet(S) and tet(W). Water from farms with recent OTC use had significantly higher tetR detection frequencies than did water from farms without recent OTC use, with prevalence in raceways and rearing ponds of farms with recent OTC use exceeded by more than two-fold that of farms not using OTC. Effluent from all farms, regardless of treatment regime, had higher tetR detection frequencies than their corresponding influent for all genes, but the specific combinations of tetR genes detected in a sample were not different from their corresponding influent. Although OTC use was associated with the increased occurrence and diversity of tetR genes in water samples, it was not found to relate to tetR gene occurrence in sediment samples. Sediment samples from facilities with no recent OTC use had significantly higher frequencies of tetR gene detection than did samples from facilities with recent OTC use. All of the tetR genes were detected in both the medicated and non-medicated feed samples analyzed in this study. These findings suggest that both OTC treatment in aquaculture facilities, and the farms themselves, may be sources of tetR gene introduction to the environment. To our knowledge, this is the first study to use genotypic and cultivation-independent methods to examine tetR gene occurrence associated with OTC use in aquaculture. PMID:20217406

CYP3A4 and CYP3A5 genotyping by Pyrosequencing

PubMed Central

Garsa, Adam A; McLeod, Howard L; Marsh, Sharon

2005-01-01

Background Human cytochrome P450 3A enzymes, particularly CYP3A4 and CYP3A5, play an important role in drug metabolism. CYP3A expression exhibits substantial interindividual variation, much of which may result from genetic variation. This study describes Pyrosequencing assays for key SNPs in CYP3A4 (CYP3A4*1B, CYP3A4*2, and CYP3A4*3) and CYP3A5 (CYP3A5*3C and CYP3A5*6). Methods Genotyping of 95 healthy European and 95 healthy African volunteers was performed using Pyrosequencing. Linkage disequilibrium, haplotype inference, Hardy-Weinberg equilibrium, and tag SNPs were also determined for these samples. Results CYP3A4*1B allele frequencies were 4% in Europeans and 82% in Africans. The CYP3A4*2 allele was found in neither population sample. CYP3A4*3 had an allele frequency of 2% in Europeans and 0% in Africans. The frequency of CYP3A5*3C was 94% in Europeans and 12% in Africans. No CYP3A5*6 variants were found in the European samples, but this allele had a frequency of 16% in the African samples. Allele frequencies and haplotypes show interethnic variation, highlighting the need to analyze clinically relevant SNPs and haplotypes in a variety of ethnic groups. Conclusion Pyrosequencing is a versatile technique that could improve the efficiency of SNP analysis for pharmacogenomic research with the ultimate goal of pre-screening patients for individual therapy selection. PMID:15882469

Study on sound-speed dispersion in a sandy sediment at frequency ranges of 0.5-3 kHz and 90-170 kHz

NASA Astrophysics Data System (ADS)

Yu, Sheng-qi; Liu, Bao-hua; Yu, Kai-ben; Kan, Guang-ming; Yang, Zhi-guo

2017-03-01

In order to study the properties of sound-speed dispersion in a sandy sediment, the sound speed was measured both at high frequency (90-170 kHz) and low frequency (0.5-3 kHz) in laboratory environments. At high frequency, a sampling measurement was conducted with boiled and uncooked sand samples collected from the bottom of a large water tank. The sound speed was directly obtained through transmission measurement using single source and single hydrophone. At low frequency, an in situ measurement was conducted in the water tank, where the sandy sediment had been homogeneously paved at the bottom for a long time. The sound speed was indirectly inverted according to the traveling time of signals received by three buried hydrophones in the sandy sediment and the geometry in experiment. The results show that the mean sound speed is approximate 1710-1713 m/s with a weak positive gradient in the sand sample after being boiled (as a method to eliminate bubbles as much as possible) at high frequency, which agrees well with the predictions of Biot theory, the effective density fluid model (EDFM) and Buckingham's theory. However, the sound speed in the uncooked sandy sediment obviously decreases (about 80%) both at high frequency and low frequency due to plenty of bubbles in existence. And the sound-speed dispersion performs a weak negative gradient at high frequency. Finally, a water-unsaturated Biot model is presented for trying to explain the decrease of sound speed in the sandy sediment with plenty of bubbles.

Migraine headaches and mood/anxiety disorders in the ELSA Brazil.

PubMed

Goulart, Alessandra C; Santos, Itamar S; Brunoni, André R; Nunes, Maria Angélica; Passos, Valéria M; Griep, Rosane H; Lotufo, Paulo A; Benseñor, Isabela M

2014-09-01

To describe the relationship between mood/anxiety disorders and migraine headaches emphasizing the frequency of episodes based in a cross-sectional analysis in the Brazilian Longitudinal Study of Adult Health. It has been suggested that frequency of migraine headaches can be directly associated with the presence of psychiatric disorders. Migraine headaches (International Headache Society criteria) was classified as <1×/month, 1×/month-1×/week, 2-6×/week, and daily. Psychiatric disorders using the Clinical Interview Schedule - Revised were classified in 6 categories: common mental (CMD), major depressive (MDD), generalized anxiety (GAD), panic, obsessive-compulsive (OCD), and mixed anxiety and depressive (MADD) disorders. We performed multivariate logistic models adjusted for age, race, education, marital status, income, and use of selective serotonin reuptake inhibitors. In our sample, 1261 presented definite migraine and 10,531 without migraine headaches (reference). Our main result was an increase in the strength of association between migraine and MDD as frequency of migraine increased for all sample: odds ratio of 2.14 (95% confidence interval [CI] 1.33-3.43) for <1 episode of migraine/month to 6.94 (95% CI 4.20-11.49) for daily headaches for all sample. Significant associations with migraine were also found for GAD, OCD, MADD, and CMD for total sample: MDD, GAD, OCD, MADD, and CMD for women, and MADD and CMD for men. Among men with daily migraine complaint, we found a significant association between migraine and OCD after correction for multiple comparisons (odds ratio 29.86 [95% CI 4.66-191.43]). Analyzing probable and definite migraine cases together, we replicated the findings in a lower magnitude. The increase in migraine frequency was associated with progressively higher frequencies of having mood/anxiety disorders in all samples suggesting for some psychiatric disorders a likely dose-response effect especially for women. © 2014 American Headache Society.

Detection frequency of human herpesviruses-6A, -6B, and -7 genomic sequences in central nervous system DNA samples from post-mortem individuals with unspecified encephalopathy.

PubMed

Chapenko, Svetlana; Roga, Silvija; Skuja, Sandra; Rasa, Santa; Cistjakovs, Maksims; Svirskis, Simons; Zaserska, Zane; Groma, Valerija; Murovska, Modra

2016-08-01

In this autopsy-based study, human herpesvirus-6 (HHV-6) and -7 (HHV-7) genomic sequence frequency, HHV-6 variants, HHV-6 load and the expression of HHV-6 antigens in brain samples from the individuals, with and without unspecified encephalopathy (controls), using nested and real-time polymerase chain reactions, restriction endonuclease, and immunohistochemical analysis were examined. GraphPad Prism 6.0 Mann-Whitney nonparametric and chi-square test and Fisher's exact test were used for statistical analysis. The encephalopathy diagnoses were shown by magnetic resonance imaging made during their lifetime and macro- and microscopically studied autopsy tissue materials. Widespread HHV-6 and/or HHV-7 positivity was detected in the brain tissue of various individuals with encephalopathy, as well as in controls (51/57, 89.4 % and 35/51, 68.6 %, respectively; p = 0.009). Significantly higher detection frequency of single HHV-6 and concurrent HHV-6 + HHV-7 DNA was found in pia mater meninges, frontal lobe, temporal lobe, and olfactory tract DNAs in individuals with encephalopathy compared to the control group. HHV-6 load and higher frequency of the viral load >10 copies/10(6) cells significantly differed in samples from individuals with and without encephalopathy. The expression of HHV-6 antigens was revealed in different neural cell types with strong predominance in the encephalopathy group. In all HHV-6-positive autopsy samples of individuals with and without encephalopathy, HHV-6B was revealed. Significantly higher detection frequency of beta-herpesvirus DNA, more often detected HHV-6 load >10 copies/10(6) cells, as well as the expression of HHV-6 antigens in different brain tissue samples from individuals with encephalopathy in comparison with control group indicate on potential involvement of these viruses in encephalopathy development.

Micronucleus test in fish from a pampasic pond (Argentina): an estimation of the presence of genotoxic compounds.

PubMed

Campana, M A; Panzeri, A M; Escalante, A H; Moreno, V J; Dulout, F N

2001-01-01

The Los Padres pond is one of the commonly shallow, polymictic lakes from the so-called depressed Pampa (Argentina). Its watershed includes one affluent, named Los Padres creek, which flows through horticultural lands wherein great amounts of pesticides are applied. Opposite to this stream, the pond drains into La Tapera creek that is the effluent running toward the sea. Many studies have confirmed the capacity of various pesticides to induce genetic damage. The use of micronucleus (MN) tests in fish has enabled us to detect the presence of contaminants in the lakewater and to evaluate theirgenotoxic effects. For this purpose, water samples were collected during April, August, and December 1999 from both creeks characterized by different environmental conditions. In the laboratory, specimens oftetras Cheirodon interruptus (Pisces, Characidae) were reared in water samples from the two creeks. Control fish were kept in drinking water. Fifteen individuals from each experimental group were sacrificed after 24-, 48-, and 72-hour exposure intervals. Micronucleus frequency in fish erythrocytes was determined, and the Kruskal-Wallis test for statistic analysis was used. We made the following observations: (1) Highly significant differences occurred in MN frequency between the control group and the samples from both creeks. (2) An increase in MN frequency was evident in specimens sampled from the affluent input during the month of December. These results allowed us to conclude that the increase in MN frequency observed in fish belonging to both sampling sites would indicate the existence of genotoxic compounds in the Los Padres pond. The high MN frequency in fish collected near Los Padres creek inlet might be related to the polluted load transported by the affluent and discharged into the lake's surface waters. Future work would allow us to develop efficient methods for predicting the presence of genotoxic contaminants. It would be possible then to propose strategies for regulating and decreasing the sources of pollution that affect human health.

Frequency-Modulation Correlation Spectrometer

NASA Technical Reports Server (NTRS)

Margolis, J. S.; Martonchik, J. V.

1985-01-01

New type of correlation spectrometer eliminates need to shift between two cells, one empty and one containing reference gas. Electrooptical phase modulator sinusoidally shift frequencies of sample transmission spectrum.

Occurrence of trihalomethanes in the nation's ground water and drinking-water supply wells, 1985-2002

USGS Publications Warehouse

Schaap, Bryan D.; Zogorski, John S.

2006-01-01

This report describes the occurrence of trihalomethanes (THMs) in the Nation's ground water and drinking-water supply wells based on analysis of 5,642 samples of untreated ground water and source water collected or compiled during 1985-2002 by the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. THMs are a group of volatile organic compounds (VOCs) with natural and anthropogenic sources that are of interest because they are associated with acute and chronic health problems in humans. THMs occur in water primarily from chlorination and are classified as disinfection by-products. In this report, the four THMs are discussed in the order of chloroform, bromodichloromethane, dibromochloromethane, and then bromoform; this sequence corresponds to largest to smallest chlorine content and smallest to largest bromine content. Four trihalomethanes were detected in less than 20 percent of samples from studies of (1) aquifers, (2) shallow ground water in agricultural areas, (3) shallow ground water in urban areas, (4) domestic wells, and (5) public wells. Detection frequencies for individual THMs in the five studies ranged from zero for shallow ground water in agricultural areas to 19.5 percent for shallow ground water in urban areas. None of the samples from aquifer studies, domestic wells, or public wells had total THM concentrations (the sum of the concentrations of chloroform, bromodichloromethane, dibromochloromethane, and bromoform) greater than or equal to the U.S. Environmental Protection Agency Maximum Contaminant Level of 80 micrograms per liter (?g/L). Comparisons of results among studies of aquifers, shallow ground water in agricultural areas, and shallow ground water in urban areas were used to describe the occurrence of the four THMs in ground water for three different land-use settings-mixed, agricultural, and urban, respectively. At the 0.2-?g/L assessment level, one or more of the four THMs were detected in 7.9 percent of the samples from aquifer studies, 2.2 percent of the samples from shallow ground water in agricultural areas, and 19.5 percent of the samples from shallow ground water in urban areas. In general, detection frequencies and concentrations of the four THMs were greater in shallow ground water in urban areas compared to aquifer studies and to shallow ground water in agricultural areas. For all three of these studies, the most common two-THM mixture at the 0.2-?g/L assessment level was chloroform-bromodichloromethane, and this was the only two-THM mixture found in samples of shallow ground water in agricultural areas. Comparisons of results between studies of domestic wells and public wells were used to describe the occurrence of the four THMs in two different supplies of ground water used for drinking water. At the 0.2-?g/L assessment level, one or more of the four THMs were detected in 5.2 percent of the domestic well samples and in 14.7 percent of the public well samples. In general, detection frequencies and THM concentrations were greater in samples from public wells than from domestic wells. At the 0.2-?g/L assessment level, the six possible two-THM mixtures occurred about six times more frequently in samples from public wells than from domestic wells. One of the most common two-THM mixtures in samples from domestic and public wells was bromodichloromethane-dibromochloromethane. Detection frequency is associated with the chlorine content of the THM compound. In general, for each of the five studies, as the chlorine content of the THM compound decreased, the detection frequency at the 0.2-?g/L assessment level also decreased. The exception was the study of public wells in which the detection frequency of the THMs decreased in the following order: chloroform, bromoform, dibromochloromethane, and bromodichloromethane. At the 0.2-?g/L assessment level, the median concentration for one or more of the four THMs ranged from 0.3 ?g/L (shallow ground water in agricultural a

Frequency of lucid dreaming in a representative German sample.

PubMed

Schredl, Michael; Erlacher, Daniel

2011-02-01

Lucid dreams occur when a person is aware that he is dreaming while he is dreaming. In a representative sample of German adults (N = 919), 51% of the participants reported that they had experienced a lucid dream at least once. Lucid dream recall was significantly higher in women and negatively correlated with age. However, these effects might be explained by the frequency of dream recall, as there was a correlation of .57 between frequency of dream recall and frequency of lucid dreams. Other sociodemographic variables like education, marital status, or monthly income were not related to lucid dream frequency. Given the relatively high prevalence of lucid dreaming reported in the present study, research on lucid dreams might be pursued in the sleep laboratory to expand the knowledge about sleep, dreaming, and consciousness processes in general.

Stochastic Investigation of Natural Frequency for Functionally Graded Plates

NASA Astrophysics Data System (ADS)

Karsh, P. K.; Mukhopadhyay, T.; Dey, S.

2018-03-01

This paper presents the stochastic natural frequency analysis of functionally graded plates by applying artificial neural network (ANN) approach. Latin hypercube sampling is utilised to train the ANN model. The proposed algorithm for stochastic natural frequency analysis of FGM plates is validated and verified with original finite element method and Monte Carlo simulation (MCS). The combined stochastic variation of input parameters such as, elastic modulus, shear modulus, Poisson ratio, and mass density are considered. Power law is applied to distribute the material properties across the thickness. The present ANN model reduces the sample size and computationally found efficient as compared to conventional Monte Carlo simulation.

The frequency dependence of the viscous component of the magnetic susceptibility of lunar rock and soil samples

NASA Technical Reports Server (NTRS)

Hanneken, J. W.; Vant-Hull, L. L.; Carnes, J. G.

1976-01-01

The susceptibility of two lunar samples (a soil and a low metamorphic grade breccia) has been measured in a weak field - 0.001 Oe - and as a function of frequency from 0.032 to 1.0 Hz. The measurements were made using a superconducting magnetometer. The results show that the susceptibility decreases linearly with the log of frequency. This observation is in agreement with a theoretical model for viscous decay based on the Neel theory of single-domain and superparamagnetic grains. The relation derived agrees with a model in which there is a uniform distribution of relaxation times.

The impedance spectroscopy analysis of complex perovskite Sr2YbSbO6

NASA Astrophysics Data System (ADS)

Barua, A.; Maity, S.; Mondal, R.; Kumar, S.

2018-04-01

Herein, we have reported the dielectric properties of single phase monoclinic double perovskite oxide of Sr2YbSbO6 having lattice parameter a=5.79 Å, b=5.79 Å, c=8.19 Å and β = 90.136° with grain size ranging between 0.5 to 2.4 µm. The sample has been synthesized by solid state ceramic method. We have performed the impedence spectroscopic study of the sample in the frequency range of 40 Hz to 5 MHz at various temperatures. The relaxation in the sample is polydispersive in nature and obeys the Cole-Cole model. The values of dielectric permittivity and loss tangent at room temperature are 117.94 and 0.18 respectively. The temperature variation of dc conductivity follows the Arrhenius Law with activation energy 0.2 eV and the conduction mechanism of the sample is governed by p-type polaron hopping. Due to its high dielectric permittivity and low loss tangent the sample can be fruitfully utilized for the fabrication of radio frequency devices.

Microwave dielectric spectrum of rocks

NASA Technical Reports Server (NTRS)

Ulaby, F. T.; Bengal, T.; East, J.; Dobson, M. C.; Garvin, J.; Evans, D.

1988-01-01

A combination of several measurement techniques was used to investigate the dielectric properties of 80 rock samples in the microwave region. The real part of the dielectric constant, epsilon', was measured in 0.1 GHz steps from 0.5 to 18 GHz, and the imaginary part, epsilon'', was measured at five frequencies extending between 1.6 and 16 GHz. In addition to the dielectric measurements, the bulk density was measured for all the samples and the bulk chemical composition was determined for 56 of the samples. The study shows that epsilon' is frequency-dependent over the 0.5 to 18 GHz range for all rock samples, and that the bulk density rho accounts for about 50 percent of the observed variance of epsilon'. For individual rock types (by genesis), about 90 percent of the observed variance may be explained by the combination of density and the fractional contents of SiO2, Fe2O3, MgO, and TiO2. For the loss factor epsilon'', it was not possible to establish statistically significant relationships between it and the measured properties of the rock samples (density and chemical composition).

High Frequency of Human Blood in Triatoma dimidiata Captured Inside Dwellings in a Rural Community in the Yucatan Peninsula, Mexico, but Low Antibody Seroprevalence and Electrocardiographic Findings Compatible with Chagas Disease in Humans

PubMed Central

Monteon, Victor; Alducin, César; Hernández, Jorge; Ramos-Ligonio, Angel; Lopez, Ruth

2013-01-01

We studied a small rural community of 411 inhabitants localized in the state of Campeche in the Yucatan Peninsula, Mexico. In 44 collected triatomines captured inside the houses, human feeding source was revealed in 23 of 44 (52%) samples, and chicken feeding source was revealed in 16 of 44 (36%) samples. In a set of 29 triatomines, mouse was the feeding source in 13 (44%) samples, and dog was the feeding source in 7 (24%) samples. Infection index with Trypanosoma cruzi in collected triatomines was 38%, and all parasites belonged to discrete type unit I. Inhabitants referred high contact with triatomine's bite in 60 of 128 (47%) samples, but seroprevalence was 2.3% (3/128). Evidence of electrocardiographic alteration compatible with Chagas disease was observed only in one asymptomatic seropositive subject. In conclusion, Triatoma dimidiata in this region are preferentially infected with T. cruzi I and feed on human beings with relative high frequency, but seroprevalence and Chagas disease in humans is relatively low. PMID:23296447

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1−xZnxFe2O4/NBR Composites over 2–12.4 GHz: A Strategic Material System for Stealth Applications

PubMed Central

Saini, Lokesh; Patra, Manoj Kumar; Jani, Raj Kumar; Gupta, Goutam Kumar; Dixit, Ambesh; Vadera, Sampat Raj

2017-01-01

The gel to carbonate precipitate route has been used for the synthesis of Ni1−xZnxFe2O4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > −1.2 over the entire 2–10 GHz frequency range with an optimum value ~−1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications. PMID:28294151

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1-xZnxFe2O4/NBR Composites over 2-12.4 GHz: A Strategic Material System for Stealth Applications.

PubMed

Saini, Lokesh; Patra, Manoj Kumar; Jani, Raj Kumar; Gupta, Goutam Kumar; Dixit, Ambesh; Vadera, Sampat Raj

2017-03-15

The gel to carbonate precipitate route has been used for the synthesis of Ni 1-x Zn x Fe 2 O 4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδ m ) > -1.2 over the entire 2-10 GHz frequency range with an optimum value ~-1.75 at 6 GHz. Ni 0.5 Zn 0.5 Fe 2 O 4 - Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni 0.5 Zn 0.5 Fe 2 O 4 /NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (f m1 ) and destructive interference at λ m /4 matched thickness near ~10 GHz (f m2 ) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni 0.5 Zn 0.5 Fe 2 O 4 /NBR composite samples for possible microwave absorption applications.

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1-xZnxFe2O4/NBR Composites over 2-12.4 GHz: A Strategic Material System for Stealth Applications

NASA Astrophysics Data System (ADS)

Saini, Lokesh; Patra, Manoj Kumar; Jani, Raj Kumar; Gupta, Goutam Kumar; Dixit, Ambesh; Vadera, Sampat Raj

2017-03-01

The gel to carbonate precipitate route has been used for the synthesis of Ni1-xZnxFe2O4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > -1.2 over the entire 2-10 GHz frequency range with an optimum value ~-1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications.

Understanding Zipf's law of word frequencies through sample-space collapse in sentence formation

PubMed Central

Thurner, Stefan; Hanel, Rudolf; Liu, Bo; Corominas-Murtra, Bernat

2015-01-01

The formation of sentences is a highly structured and history-dependent process. The probability of using a specific word in a sentence strongly depends on the ‘history’ of word usage earlier in that sentence. We study a simple history-dependent model of text generation assuming that the sample-space of word usage reduces along sentence formation, on average. We first show that the model explains the approximate Zipf law found in word frequencies as a direct consequence of sample-space reduction. We then empirically quantify the amount of sample-space reduction in the sentences of 10 famous English books, by analysis of corresponding word-transition tables that capture which words can follow any given word in a text. We find a highly nested structure in these transition tables and show that this ‘nestedness’ is tightly related to the power law exponents of the observed word frequency distributions. With the proposed model, it is possible to understand that the nestedness of a text can be the origin of the actual scaling exponent and that deviations from the exact Zipf law can be understood by variations of the degree of nestedness on a book-by-book basis. On a theoretical level, we are able to show that in the case of weak nesting, Zipf's law breaks down in a fast transition. Unlike previous attempts to understand Zipf's law in language the sample-space reducing model is not based on assumptions of multiplicative, preferential or self-organized critical mechanisms behind language formation, but simply uses the empirically quantifiable parameter ‘nestedness’ to understand the statistics of word frequencies. PMID:26063827

A continuously weighing, high frequency sand trap: Wind tunnel and field evaluations

NASA Astrophysics Data System (ADS)

Yang, Fan; Yang, XingHua; Huo, Wen; Ali, Mamtimin; Zheng, XinQian; Zhou, ChengLong; He, Qing

2017-09-01

A new continuously weighing, high frequency sand trap (CWHF) has been designed. Its sampling efficiency is evaluated in a wind tunnel and the potential of the new trap has been demonstrated in field trials. The newly designed sand trap allows fully automated and high frequency measurement of sediment fluxes over extensive periods. We show that it can capture the variations and structures of wind-driven sand transport processes and horizontal sediment flux, and reveal the relationships between sand transport and meteorological parameters. Its maximum sampling frequency can reach 10 Hz. Wind tunnel tests indicated that the sampling efficiency of the CWHF sand trap varies between 39.2 to 64.3%, with an average of 52.5%. It achieved a maximum sampling efficiency of 64.3% at a wind speed of 10 m s- 1. This is largely achieved by the inclusion of a vent hole which leads to a higher sampling efficiency than that of a step-like sand trap at high wind speeds. In field experiments, we show a good agreement between the mass of sediment from the CWHF sand trap, the wind speed at 2 m and the number of saltating particles at 5 cm above the ground surface. According to analysis of the horizontal sediment flux at four heights from the CWHF sand trap (25, 35, 50, and 100 cm), the vertical distribution of the horizontal sediment flux up to a height of 100 cm above the sand surface follows an exponential function. Our field experiments show that the new instrument can capture more detailed information on sediment transport with much reduced labor requirement. Therefore, it has great potential for application in wind-blown sand monitoring and process studies.

Understanding Zipf's law of word frequencies through sample-space collapse in sentence formation.

PubMed

Thurner, Stefan; Hanel, Rudolf; Liu, Bo; Corominas-Murtra, Bernat

2015-07-06

The formation of sentences is a highly structured and history-dependent process. The probability of using a specific word in a sentence strongly depends on the 'history' of word usage earlier in that sentence. We study a simple history-dependent model of text generation assuming that the sample-space of word usage reduces along sentence formation, on average. We first show that the model explains the approximate Zipf law found in word frequencies as a direct consequence of sample-space reduction. We then empirically quantify the amount of sample-space reduction in the sentences of 10 famous English books, by analysis of corresponding word-transition tables that capture which words can follow any given word in a text. We find a highly nested structure in these transition tables and show that this 'nestedness' is tightly related to the power law exponents of the observed word frequency distributions. With the proposed model, it is possible to understand that the nestedness of a text can be the origin of the actual scaling exponent and that deviations from the exact Zipf law can be understood by variations of the degree of nestedness on a book-by-book basis. On a theoretical level, we are able to show that in the case of weak nesting, Zipf's law breaks down in a fast transition. Unlike previous attempts to understand Zipf's law in language the sample-space reducing model is not based on assumptions of multiplicative, preferential or self-organized critical mechanisms behind language formation, but simply uses the empirically quantifiable parameter 'nestedness' to understand the statistics of word frequencies. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Persistence of radiation-induced chromosome aberrations in a long-term cell culture.

PubMed

Duran, Assumpta; Barquinero, Joan Francesc; Caballín, María Rosa; Ribas, Montserrat; Barrios, Leonardo

2009-04-01

The aim of the present study was to evaluate the persistence of chromosome aberrations induced by X rays. FISH painting and mFISH techniques were applied to long-term cultures of irradiated cells. With painting, at 2 Gy the frequency of apparently simple translocations remained almost invariable during all the culture, whereas at 4 Gy a rapid decline was observed between the first and the second samples, followed by a slight decrease until the end of the culture. Apparently simple dicentrics and complex aberrations disappeared after the first sample at 2 and 4 Gy. By mFISH, at 2 Gy the frequency of complete plus one-way translocations remained invariable between the first and last sample, but at 4 Gy a 60% decline was observed. True incomplete simple translocations disappeared at 2 and 4 Gy, indicating that incompleteness could be a factor to consider when the persistence of translocations is analyzed. The analysis by mFISH showed that the frequency of complex aberrations and their complexity increased with dose and tended to disappear in the last sample. Our results indicate that the influence of dose on the decrease in the frequency of simple translocations with time postirradiation cannot be fully explained by the disappearance of true incomplete translocations and complex aberrations. The chromosome involvement was random for radiation-induced exchange aberrations and non-random for total aberrations. Chromosome 7 showed the highest deviations from expected, being less and more involved than expected in the first and last samples, respectively. Some preferential chromosome-chromosome associations were observed, including a coincidence with a cluster from radiogenic chromosome aberrations described in other studies.

Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

NASA Astrophysics Data System (ADS)

Pavithradevi, S.; Suriyanarayanan, N.; Boobalan, T.

2017-03-01

Nanocrystalline copper ferrite CuFe2O4 is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe2O4 is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe2O4 nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm-1 and 4000 cm-1. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25-34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field.

Effect of female genital schistosomiasis and anti-schistosomal treatment on monocytes, CD4+ T-cells and CCR5 expression in the female genital tract.

PubMed

Kleppa, Elisabeth; Ramsuran, Veron; Zulu, Siphosenkosi; Karlsen, Gunn Hege; Bere, Alfred; Passmore, Jo-Ann S; Ndhlovu, Patricia; Lillebø, Kristine; Holmen, Sigve D; Onsrud, Mathias; Gundersen, Svein Gunnar; Taylor, Myra; Kjetland, Eyrun F; Ndung'u, Thumbi

2014-01-01

Schistosoma haematobium is a waterborne parasite that may cause female genital schistosomiasis (FGS), characterized by genital mucosal lesions. There is clinical and epidemiological evidence for a relationship between FGS and HIV. We investigated the impact of FGS on HIV target cell density and expression of the HIV co-receptor CCR5 in blood and cervical cytobrush samples. Furthermore we evaluated the effect of anti-schistosomal treatment on these cell populations. The study followed a case-control design with post treatment follow-up, nested in an on-going field study on FGS. Blood and cervical cytobrush samples were collected from FGS negative and positive women for flow cytometry analyses. Urine samples were investigated for schistosome ova by microscopy and polymerase chain reaction (PCR). FGS was associated with a higher frequency of CD14+ cells (monocytes) in blood (11.5% in FGS+ vs. 2.2% in FGS-, p = 0.042). Frequencies of CD4+ cells expressing CCR5 were higher in blood samples from FGS+ than from FGS- women (4.7% vs. 1.5%, p = 0.018). The CD14+ cell population decreased significantly in both compartments after anti-schistosomal treatment (p = 0.043). Although the frequency of CD4+ cells did not change after treatment, frequencies of CCR5 expression by CD4+ cells decreased significantly in both compartments (from 3.4% to 0.5% in blood, p = 0.036; and from 42.4% to 5.6% in genital samples, p = 0.025). The results support the hypothesis that FGS may increase the risk of HIV acquisition, not only through damage of the mucosal epithelial barrier, but also by affecting HIV target cell populations, and that anti-schistosomal treatment can modify this.

A Monte Carlo Study of Levene's Test of Homogeneity of Variance: Empirical Frequencies of Type I Error in Normal Distributions.

ERIC Educational Resources Information Center

Neel, John H.; Stallings, William M.

An influential statistics test recommends a Levene text for homogeneity of variance. A recent note suggests that Levene's test is upwardly biased for small samples. Another report shows inflated Alpha estimates and low power. Neither study utilized more than two sample sizes. This Monte Carlo study involved sampling from a normal population for…

Chaotic rotation of Hyperion?

NASA Technical Reports Server (NTRS)

Binzel, R. P.; Green, J. R.; Opal, C. B.

1986-01-01

Thomas et al. (1984) analyzed 14 Voyager 2 images of Saturn's satellite Hyperion and interpreted them to be consistent with a coherent (nonchaotic) rotation period of 13.1 days. This interpretation was criticized by Peale and Wisdom (1984), who argued that the low sampling frequency of Voyager data does not allow chaotic or nonchaotic rotation to be distinguished. New observations obtained with a higher sampling frequency are reported here which conclusively show that the 13.1 day period found by Thomas et al. was not due to coherent rotation.

Electrical properties of lunar soil dependence on frequency, temperature and moisture.

NASA Technical Reports Server (NTRS)

Strangway, D. W.; Chapman, W. B.; Olhoeft, G. R.; Carnes, J.

1972-01-01

It was found that the dielectric constant and loss tangent of lunar soil samples in the range from 100 Hz to 1 MHz are not strongly dependent on frequency provided care is taken to avoid exposure of the sample to atmospheric air containing moisture. The loss tangent value obtained is lower by nearly a factor 10 than any previously reported value. The measurement data imply that the surface layers of the moon are probably extremely transparent to radiowaves.

Infrared absorption nano-spectroscopy using sample photoexpansion induced by tunable quantum cascade lasers.

PubMed

Lu, Feng; Belkin, Mikhail A

2011-10-10

We report a simple technique that allows obtaining mid-infrared absorption spectra with nanoscale spatial resolution under low-power illumination from tunable quantum cascade lasers. Light absorption is detected by measuring associated sample thermal expansion with an atomic force microscope. To detect minute thermal expansion we tune the repetition frequency of laser pulses in resonance with the mechanical frequency of the atomic force microscope cantilever. Spatial resolution of better than 50 nm is experimentally demonstrated.

Technique for Performing Dielectric Property Measurements at Microwave Frequencies

NASA Technical Reports Server (NTRS)

Barmatz, Martin B. (Inventor); Jackson, Henry W. (Inventor)

2014-01-01

A method, system, apparatus, and computer readable medium has been provided with the ability to obtain a complex permittivity dielectric or a complex permeability micron of a sample in a cavity. One or more complex-valued resonance frequencies f(sub m) of the cavity, wherein each f(sub m) is a measurement, are obtained. Maxwell's equations are solved exactly for dielectric, and/or micron, using the f(sub m) as known quantities, thereby obtaining the dielectric and/or micron of the sample.

Initial Data of Digital Correlation ECE with a Giga Hertz Sampling Digitizer

NASA Astrophysics Data System (ADS)

Tsuchiya, Hayato; Inagaki, Shigeru; Tokuzawa, Tokihiko; Nagayama, Yoshio

2015-03-01

The proposed Digital Correlation ECE (DCECE) technique is applied in Large Helical Device. DCECE is realized by the use of the Giga Hertz Sampling Digitizer. The waveform of intermediate frequency band of ECE, whose frequency is several giga hertz, can be discretized and saved directly. The discretized IF data can be used for the analysis of correlation ECE with arbitrary parameter of spatial resolution and temporal resolution. In this paper, the characteristic of DCECE and initial Data in LHD is introduced.

Frequency of Dental Caries in Four Historical Populations from the Chalcolithic to the Middle Ages

PubMed Central

Grimoud, A.-M.; Lucas, S.; Sevin, A.; Georges, P.; Passarrius, O.; Duranthon, F.

2011-01-01

The majority of dental carie studies over the course of historical period underline mainly the prevalence evolution, the role of carbohydrates consumption and the impact of access to dietary resources. The purpose of the present investigation was to compare population samples from two archaeological periods the Chacolithic and Middle Age taking into account the geographical and socio economical situation. The study concerned four archaelogical sites in south west France and population samples an inlander for the Chalcolithic Age, an inlander, an costal and urban for the Middle Age. The materials studied included a total of 127 maxillaries, 103 mandibles and 3316 teeth. Data recorded allowed us to display that the Chalcolithic population sample had the lowest carie percentage and the rural inlander population samples of Middle Age the highest; in all cases molars were teeth most often affected. These ones differences could be explained according to time period, carious lesions were usually less recorded in the Chalcolithic Age than the Middle because of a lesser cultivation of cereals like in les Treilles Chacolithic population sample. In the Middle Age population samples, the rural inland sample Marsan showed the highest frequency of caries and ate more cereal than the coastal Vilarnau and the poor urban St Michel population samples, the first one ate fish and Mediterranean vegetal and fruits and the second one met difficulties to food access, in both cases the consumption of carbohydrates was lesser than Marsan population sample who lived in a geographical land convice to cereals cultivation. PMID:22145000

Antibiotics in Drinking Water in Shanghai and Their Contribution to Antibiotic Exposure of School Children.

PubMed

Wang, Hexing; Wang, Na; Wang, Bin; Zhao, Qi; Fang, Hong; Fu, Chaowei; Tang, Chuanxi; Jiang, Feng; Zhou, Ying; Chen, Yue; Jiang, Qingwu

2016-03-01

A variety of antibiotics have been found in aquatic environments, but antibiotics in drinking water and their contribution to antibiotic exposure in human are not well-explored. For this, representative drinking water samples and 530 urine samples from schoolchildren were selected in Shanghai, and 21 common antibiotics (five macrolides, two β-lactams, three tetracyclines, four fluoquinolones, four sulfonamides, and three phenicols) were measured in water samples and urines by isotope dilution two-dimensional ultraperformance liquid chromatography coupled with high-resolution quadrupole time-of-flight mass spectrometry. Drinking water included 46 terminal tap water samples from different spots in the distribution system of the city, 45 bottled water samples from 14 common brands, and eight barreled water samples of different brands. Of 21 antibiotics, only florfenicol and thiamphenicol were found in tap water, with the median concentrations of 0.0089 ng/mL and 0.0064 ng/mL, respectively; only florfenicol was found in three bottled water samples from a same brand, with the concentrations ranging from 0.00060 to 0.0010 ng/mL; no antibiotics were found in barreled water. In contrast, besides florfenicol and thiamphenicol, an additional 17 antibiotics were detected in urine samples, and the total daily exposure doses and detection frequencies of florfenicol and thiamphenicol based on urine samples were significantly and substantially higher than their predicted daily exposure doses and detection frequencies from drinking water by Monte Carlo Simulation. These data indicated that drinking water was contaminated by some antibiotics in Shanghai, but played a limited role in antibiotic exposure of children.

Optimization of sampling pattern and the design of Fourier ptychographic illuminator.

PubMed

Guo, Kaikai; Dong, Siyuan; Nanda, Pariksheet; Zheng, Guoan

2015-03-09

Fourier ptychography (FP) is a recently developed imaging approach that facilitates high-resolution imaging beyond the cutoff frequency of the employed optics. In the original FP approach, a periodic LED array is used for sample illumination, and therefore, the scanning pattern is a uniform grid in the Fourier space. Such a uniform sampling scheme leads to 3 major problems for FP, namely: 1) it requires a large number of raw images, 2) it introduces the raster grid artefacts in the reconstruction process, and 3) it requires a high-dynamic-range detector. Here, we investigate scanning sequences and sampling patterns to optimize the FP approach. For most biological samples, signal energy is concentrated at low-frequency region, and as such, we can perform non-uniform Fourier sampling in FP by considering the signal structure. In contrast, conventional ptychography perform uniform sampling over the entire real space. To implement the non-uniform Fourier sampling scheme in FP, we have designed and built an illuminator using LEDs mounted on a 3D-printed plastic case. The advantages of this illuminator are threefold in that: 1) it reduces the number of image acquisitions by at least 50% (68 raw images versus 137 in the original FP setup), 2) it departs from the translational symmetry of sampling to solve the raster grid artifact problem, and 3) it reduces the dynamic range of the captured images 6 fold. The results reported in this paper significantly shortened acquisition time and improved quality of FP reconstructions. It may provide new insights for developing Fourier ptychographic imaging platforms and find important applications in digital pathology.

Reduced aliasing artifacts using shaking projection k-space sampling trajectory

NASA Astrophysics Data System (ADS)

Zhu, Yan-Chun; Du, Jiang; Yang, Wen-Chao; Duan, Chai-Jie; Wang, Hao-Yu; Gao, Song; Bao, Shang-Lian

2014-03-01

Radial imaging techniques, such as projection-reconstruction (PR), are used in magnetic resonance imaging (MRI) for dynamic imaging, angiography, and short-T2 imaging. They are less sensitive to flow and motion artifacts, and support fast imaging with short echo times. However, aliasing and streaking artifacts are two main sources which degrade radial imaging quality. For a given fixed number of k-space projections, data distributions along radial and angular directions will influence the level of aliasing and streaking artifacts. Conventional radial k-space sampling trajectory introduces an aliasing artifact at the first principal ring of point spread function (PSF). In this paper, a shaking projection (SP) k-space sampling trajectory was proposed to reduce aliasing artifacts in MR images. SP sampling trajectory shifts the projection alternately along the k-space center, which separates k-space data in the azimuthal direction. Simulations based on conventional and SP sampling trajectories were compared with the same number projections. A significant reduction of aliasing artifacts was observed using the SP sampling trajectory. These two trajectories were also compared with different sampling frequencies. A SP trajectory has the same aliasing character when using half sampling frequency (or half data) for reconstruction. SNR comparisons with different white noise levels show that these two trajectories have the same SNR character. In conclusion, the SP trajectory can reduce the aliasing artifact without decreasing SNR and also provide a way for undersampling reconstruction. Furthermore, this method can be applied to three-dimensional (3D) hybrid or spherical radial k-space sampling for a more efficient reduction of aliasing artifacts.

Transport properties of lithium- lead-vanadium-telluride glass and glass ceramics

NASA Astrophysics Data System (ADS)

Sathish, M.; Eraiah, B.

2014-04-01

Glasses with the chemical composition 35Li2O-(45-x)V2O5-20PbO-xTeO2 (where x = 2.5, 5, 7.5, 10, 15 mol %) have prepared by conventional melt quenching method. The electrical conductivity of Li+ ion conducting lead vanadium telluride glass samples has been carried out both as a function of temperature and frequency in the temperature range 503K-563K and over frequencies 40 Hz to 10 MHz. The electronic conduction has been observed in the present systems. When these samples annealed around 400°C for 2hour become the glass ceramic, which also shows increase tendency of conductivity. SEM confines glass and glass ceramic nature of the prepared samples.

Adaptive frequency-domain equalization in digital coherent optical receivers.

PubMed

Faruk, Md Saifuddin; Kikuchi, Kazuro

2011-06-20

We propose a novel frequency-domain adaptive equalizer in digital coherent optical receivers, which can reduce computational complexity of the conventional time-domain adaptive equalizer based on finite-impulse-response (FIR) filters. The proposed equalizer can operate on the input sequence sampled by free-running analog-to-digital converters (ADCs) at the rate of two samples per symbol; therefore, the arbitrary initial sampling phase of ADCs can be adjusted so that the best symbol-spaced sequence is produced. The equalizer can also be configured in the butterfly structure, which enables demultiplexing of polarization tributaries apart from equalization of linear transmission impairments. The performance of the proposed equalization scheme is verified by 40-Gbits/s dual-polarization quadrature phase-shift keying (QPSK) transmission experiments.

The study of electrical conduction mechanisms. [dielectric response of lunar fines

NASA Technical Reports Server (NTRS)

Morrison, H. F.

1974-01-01

The dielectric response of lunar fines 74241,2 is presented in the audio-frequency range and under lunarlike conditions. Results suggest that volatiles are released during storage and transport of the lunar sample. Apparently, subsequent absorption of volatiles on the sample surface alter its dielectric response. The assumed volatile influence disappear after evacuation. A comparison of the dielectric properties of lunar and terrestrial materials as a function of density, temperature, and frequency indicates that if the lunar simulator analyzed were completely devoid of atmospheric moisture it would present dielectric losses smaller than those of the lunar sample. It is concluded that density prevails over temperature as the controlling factor of dielectric permittivity in the lunar regolith and that dielectric losses vary slowly with depth.

Analysis of the herbicide diuron, three diuron degradates, and six neonicotinoid insecticides in water-Method details and application to two Georgia streams

USGS Publications Warehouse

Hladik, Michelle; Calhoun, Daniel L.

2012-01-01

A method for the determination of the widely used herbicide diuron, three degradates of diuron, and six neonicotinoid insecticides in environmental water samples is described. Filtered water samples were extracted by using solid-phase extraction (SPE) with no additional cleanup steps. Quantification of the pesticides from the extracted water samples was done by using liquid chromatography with tandem mass spectrometry (LC/MS/MS). Recoveries in test water samples fortified at 20 nanograms per liter (ng/L) for each compound ranged from 75 to 97 percent; relative standard deviations ranged from 5 to 10 percent. Method detection limits (MDLs) in water ranged from 3.0 to 6.2 ng/L using LC/MS/MS. The method was applied to water samples from two streams in Georgia, Sope Creek and the Chattahoochee River. Diuron and 3,4-dichloroaniline (3,4-DCA) were detected in 100 and 80 percent, respectively, of the samples from the Chattahoochee River, whereas Sope creek had detection frequencies of 15 percent for diuron and 31 percent for 3,4-DCA. Detection frequencies for the neonicotinoid insecticide, imidacloprid, were 60 percent for the Chattahoochee River and 85 percent for Sope Creek. Field matrix-spike recoveries for each compound, when averaged over four water samples, ranged from 79 to 100 percent. The average percentage difference between replicate pairs for all compounds detected in the field samples was 10.1 (± 4.5) percent.

Prevalence of doping in sports: doping control in Norway, 1977-1995.

PubMed

Bahr, R; Tjørnhom, M

1998-01-01

To examine the results from doping controls conducted by the Norwegian Confederation of Sport (NCS) from 1977 to 1995. Data were collected by combining three computerized databases and manual records on samples taken and results from analyses in the International Olympic Committee (IOC)-accredited laboratories in London, Huddinge, Cologne, and Oslo. Samples were declared positive if they contained any banned substance on the IOC list that was in effect at any given time. A total of 15,208 samples were taken; most of them (12,870; 85%) were from Norwegian athletes (90% unannounced tests) belonging to national federations under NCS jurisdiction (NCS members), 461 (3%) were from external Norwegian athletes (either users of private gyms or athletes in organized sports federations not affiliated with the NCS), and 1,874 (12%) were from foreign athletes (three cases with unknown affiliation). There were 130 positive samples and 24 refusals among NCS members (1.2%; men, 1.4%; women, 0.3%), 86 positive samples and 8 refusals among external Norwegian athletes (20%; men, 24%; women, 8%), and 39 positive samples and 1 refusal among foreign athletes (1.6%; men, 2.1%; women, 0.7%). A gradual decrease in the percentage of positive samples was observed among NCS members as testing frequency was increased gradually from 1987 to 1995 in the three high-prevalence sports: powerlifting, weightlifting, and athletics. An increase in the test frequency of doping tests was associated with a decrease in the percentage of positive samples in targeted sports.

Smoking status and self-reported race affect the frequency of clinically relevant oncogenic alterations in non-small-cell lung cancers at a United States-based academic medical practice.

PubMed

Yamaguchi, Norihiro; Vanderlaan, Paul A; Folch, Erik; Boucher, David H; Canepa, Hannah M; Kent, Michael S; Gangadharan, Sidharta P; Majid, Adnan; Kocher, Olivier N; Goldstein, Michael A; Huberman, Mark S; Costa, Daniel B

2013-10-01

The identification of somatic genomic aberrations in non-small-cell lung cancer (NSCLC) is part of evidence-based practice guidelines for care of patients with NSCLC. We sought to establish the frequency and correlates with these changes in routine patient-tumor sample pairs. Clinicopathologic data and tumor genotype were retrospectively compiled and analyzed from an overall cohort of 381 patient-tumor samples. Of these patients, 75.9% self-reported White race, 13.1% Asian, 6.5% Black, 27.8% were never-smokers, 54.9% former-smokers and 17.3% current-smokers. The frequency of EGFR mutations was 23.9% (86/359), KRAS mutations 34.2% (71/207) and ALK FISH positivity 9.1% (23/252) in tumor samples, and almost all had mutually exclusive results for these oncogenes. In tumors from White, Black and Asian patients, the frequencies of EGFR mutations were 18.4%, 18.2% and 62%, respectively; of ALK FISH positivity 7.81%, 0% and 14.8%, respectively; and of KRAS mutations 41.6%, 20% and 0%. These patterns changed significant with increasing pack-year history of smoking. In White patients, the frequencies of EGFR mutations and ALK FISH positivity decreased with increasing pack-year cohorts; while the frequencies of KRAS mutations increased. Interestingly, in Asian patients the frequencies of EGFR mutations were similar in never smokers and in the cohorts with less than 45pack-year histories of smoking and only decreased in the 45pack-year plus cohort. The frequencies of somatic EGFR, KRAS, and ALK gene abnormalities using routine lung cancer tissue samples from our United States-based academic medical practice reflect the diverse ethnicity (with a higher frequency of EGFR mutations in Asian patients) and smoking patterns (with an inverse correlation between EGFR mutation and ALK rearrangement) of our tested population. These results may help other medical practices appreciate the expected results from introduction of routine tumor genotyping techniques into their day-to-day care of NSCLC. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Seasonal and high-resolution variability in hydrochemistry of the Andes-Amazon

NASA Astrophysics Data System (ADS)

Burt, E.; West, A. J.

2017-12-01

Stream hydrochemistry acts as a record of integrated catchment processes such as the amount of time it takes precipitation to flow through the subsurface and become streamflow (water transit times), water-rock interaction and biogeochemical cycling. Although it is understood that sampling interval affects observed patterns in hydrochemistry, most studies collect samples on a weekly, bi-weekly or monthly schedule due to lack of resources or the difficulty of maintaining automated sampling devices. Here, we attempt to combine information from two sampling time scales, comparing a year-long hydrochemical time series to data from a recent sub-daily sampling campaign. Starting in April 2016, river, soil and rain waters have been collected every two weeks at five small catchments spanning the tropical Andes and Amazon - a natural laboratory for its gradients in topography, erosion rates, precipitation, temperature and flora. Between January and March, 2017, we conducted high frequency sampling for approximately one week at each catchment, sampling at least every four hours including overnight. We will constrain young water fractions (Kirchner, 2016) and storm water fluxes for the experimental catchments using stable isotopes of water as conservative tracers. Major element data will provide the opportunity to make initial constraints on geochemical and hydrologic coupling. Preliminary results suggest that in the Amazon, hydrochemistry patterns are dependent on sampling frequency: the seasonal cycle in stable isotopes of water is highly damped, while the high resolution sampling displays large variability. This suggests that a two-week sampling interval is not frequent enough to capture rapid transport of water, perhaps through preferential flow networks. In the Andes, stable isotopes of water are highly damped in both the seasonal and high resolution cycle, suggesting that the catchment behaves as a "well-mixed" system.

Occurrence of transferable antibiotic resistances in commercialized ready-to-eat mealworms (Tenebrio molitor L.).

PubMed

Osimani, Andrea; Cardinali, Federica; Aquilanti, Lucia; Garofalo, Cristiana; Roncolini, Andrea; Milanović, Vesna; Pasquini, Marina; Tavoletti, Stefano; Clementi, Francesca

2017-12-18

The present study aimed to assess the occurrence of transferable determinants conferring resistance to tetracyclines, macrolide-lincosamide-streptogramin B, vancomycin, beta-lactams, and aminoglycosides in 40 samples of commercialized edible mealworms (Tenebrio molitor L.) purchased from European Union (EU) and non-EU producers. A high prevalence of tet(K) was observed in all of the samples assayed, with percentages of PCR-based positivity that ranged from 80% (samples from Thailand) to 100% (samples from the Netherlands, Belgium and France). For macrolides, erm(B) prevailed, being detected in 57.5% of the samples assayed, whereas erm(A) and erm(C) were detected with lower frequencies. Genes for resistance to vancomycin were only detected in samples produced in France and Belgium, with 90% and 10% of the samples being positive for vanA, respectively. Beta-lactamase genes were found with low occurrence, whereas the gene aac-aph, conferring high resistance to aminoglycosides, was found in 40% of the samples produced in the Netherlands and Belgium and 20% of the samples produced in Thailand. The results of Principal Coordinate Analysis and Principal Component Analysis depicted a clean separation of the samples collected from the four producers based on the distribution of the 12 AR determinants considered. Given the growing interest on the use of mealworms as a novel protein source, AR detection frequencies found in the present study suggest further investigation into the use of antibiotics during rearing of this insect species and more extensive studies focused on the factors that can affect the diffusion of transferable ARs in the production chain. Until such studies are completed, prudent use of antibiotics during rearing of edible insects is recommended. Copyright © 2017 Elsevier B.V. All rights reserved.

Sub-millimeter wave frequency heterodyne detector system

NASA Technical Reports Server (NTRS)

Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

2009-01-01

The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

Sub-millimeter wave frequency heterodyne detector system

NASA Technical Reports Server (NTRS)

Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

2010-01-01

The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

Method, system and computer-readable media for measuring impedance of an energy storage device

DOEpatents

Morrison, John L.; Morrison, William H.; Christophersen, Jon P.; Motloch, Chester G.

2016-01-26

Real-time battery impedance spectrum is acquired using a one-time record. Fast Summation Transformation (FST) is a parallel method of acquiring a real-time battery impedance spectrum using a one-time record that enables battery diagnostics. An excitation current to a battery is a sum of equal amplitude sine waves of frequencies that are octave harmonics spread over a range of interest. A sample frequency is also octave and harmonically related to all frequencies in the sum. A time profile of this sampled signal has a duration that is a few periods of the lowest frequency. A voltage response of the battery, average deleted, is an impedance of the battery in a time domain. Since the excitation frequencies are known and octave and harmonically related, a simple algorithm, FST, processes the time profile by rectifying relative to sine and cosine of each frequency. Another algorithm yields real and imaginary components for each frequency.

Evaluation of multiple-frequency, active and passive acoustics as surrogates for bedload transport

USGS Publications Warehouse

Wood, Molly S.; Fosness, Ryan L.; Pachman, Gregory; Lorang, Mark; Tonolla, Diego

2015-01-01

The use of multiple-frequency, active acoustics through deployment of acoustic Doppler current profilers (ADCPs) shows potential for estimating bedload in selected grain size categories. The U.S. Geological Survey (USGS), in cooperation with the University of Montana (UM), evaluated the use of multiple-frequency, active and passive acoustics as surrogates for bedload transport during a pilot study on the Kootenai River, Idaho, May 17-18, 2012. Four ADCPs with frequencies ranging from 600 to 2000 kHz were used to measure apparent moving bed velocities at 20 stations across the river in conjunction with physical bedload samples. Additionally, UM scientists measured the sound frequencies of moving particles with two hydrophones, considered passive acoustics, along longitudinal transects in the study reach. Some patterns emerged in the preliminary analysis which show promise for future studies. Statistically significant relations were successfully developed between apparent moving bed velocities measured by ADCPs with frequencies 1000 and 1200 kHz and bedload in 0.5 to 2.0 mm grain size categories. The 600 kHz ADCP seemed somewhat sensitive to the movement of gravel bedload in the size range 8.0 to 31.5 mm, but the relation was not statistically significant. The passive hydrophone surveys corroborated the sample results and could be used to map spatial variability in bedload transport and to select a measurement cross-section with moving bedload for active acoustic surveys and physical samples.

A versatile design for resonant guided-wave parametric down-conversion sources for quantum repeaters

NASA Astrophysics Data System (ADS)

Brecht, Benjamin; Luo, Kai-Hong; Herrmann, Harald; Silberhorn, Christine

2016-05-01

Quantum repeaters—fundamental building blocks for long-distance quantum communication—are based on the interaction between photons and quantum memories. The photons must fulfil stringent requirements on central frequency, spectral bandwidth and purity in order for this interaction to be efficient. We present a design scheme for monolithically integrated resonant photon-pair sources based on parametric down-conversion in nonlinear waveguides, which facilitate the generation of such photons. We investigate the impact of different design parameters on the performance of our source. The generated photon spectral bandwidths can be varied between several tens of MHz up to around 1 GHz, facilitating an efficient coupling to different memories. The central frequency of the generated photons can be coarsely tuned by adjusting the pump frequency, poling period and sample temperature, and we identify stability requirements on the pump laser and sample temperature that can be readily fulfilled with off-the-shelf components. We find that our source is capable of generating high-purity photons over a wide range of photon bandwidths. Finally, the PDC emission can be frequency fine-tuned over several GHz by simultaneously adjusting the sample temperature and pump frequency. We conclude our study with demonstrating the adaptability of our source to different quantum memories.

Genetic differentiation among North Atlantic killer whale populations.

PubMed

Foote, Andrew D; Vilstrup, Julia T; De Stephanis, Renaud; Verborgh, Philippe; Abel Nielsen, Sandra C; Deaville, Robert; Kleivane, Lars; Martín, Vidal; Miller, Patrick J O; Oien, Nils; Pérez-Gil, Monica; Rasmussen, Morten; Reid, Robert J; Robertson, Kelly M; Rogan, Emer; Similä, Tiu; Tejedor, Maria L; Vester, Heike; Víkingsson, Gísli A; Willerslev, Eske; Gilbert, M Thomas P; Piertney, Stuart B

2011-02-01

Population genetic structure of North Atlantic killer whale samples was resolved from differences in allele frequencies of 17 microsatellite loci, mtDNA control region haplotype frequencies and for a subset of samples, using complete mitogenome sequences. Three significantly differentiated populations were identified. Differentiation based on microsatellite allele frequencies was greater between the two allopatric populations than between the two pairs of partially sympatric populations. Spatial clustering of individuals within each of these populations overlaps with the distribution of particular prey resources: herring, mackerel and tuna, which each population has been seen predating. Phylogenetic analyses using complete mitogenomes suggested two populations could have resulted from single founding events and subsequent matrilineal expansion. The third population, which was sampled at lower latitudes and lower density, consisted of maternal lineages from three highly divergent clades. Pairwise population differentiation was greater for estimates based on mtDNA control region haplotype frequencies than for estimates based on microsatellite allele frequencies, and there were no mitogenome haplotypes shared among populations. This suggests low or no female migration and that gene flow was primarily male mediated when populations spatially and temporally overlap. These results demonstrate that genetic differentiation can arise through resource specialization in the absence of physical barriers to gene flow. © 2010 Blackwell Publishing Ltd.

Population frequencies of the Triallelic 5HTTLPR in six Ethnicially diverse samples from North America, Southeast Asia, and Africa.

PubMed

Haberstick, Brett C; Smolen, Andrew; Williams, Redford B; Bishop, George D; Foshee, Vangie A; Thornberry, Terence P; Conger, Rand; Siegler, Ilene C; Zhang, Xiaodong; Boardman, Jason D; Frajzyngier, Zygmunt; Stallings, Michael C; Brent Donnellan, M; Halpern, Carolyn T; Harris, Kathleen Mullan

2015-03-01

Genetic differences between populations are potentially an important contributor to health disparities around the globe. As differences in gene frequencies influence study design, it is important to have a thorough understanding of the natural variation of the genetic variant(s) of interest. Along these lines, we characterized the variation of the 5HTTLPR and rs25531 polymorphisms in six samples from North America, Southeast Asia, and Africa (Cameroon) that differ in their racial and ethnic composition. Allele and genotype frequencies were determined for 24,066 participants. Results indicated higher frequencies of the rs25531 G-allele among Black and African populations as compared with White, Hispanic and Asian populations. Further, we observed a greater number of 'extra-long' ('XL') 5HTTLPR alleles than have previously been reported. Extra-long alleles occurred almost entirely among Asian, Black and Non-White Hispanic populations as compared with White and Native American populations where they were completely absent. Lastly, when considered jointly, we observed between sample differences in the genotype frequencies within racial and ethnic populations. Taken together, these data underscore the importance of characterizing the L-G allele to avoid misclassification of participants by genotype and for further studies of the impact XL alleles may have on the transcriptional efficiency of SLC6A4.

Blind identification of full-field vibration modes of output-only structures from uniformly-sampled, possibly temporally-aliased (sub-Nyquist), video measurements

NASA Astrophysics Data System (ADS)

Yang, Yongchao; Dorn, Charles; Mancini, Tyler; Talken, Zachary; Nagarajaiah, Satish; Kenyon, Garrett; Farrar, Charles; Mascareñas, David

2017-03-01

Enhancing the spatial and temporal resolution of vibration measurements and modal analysis could significantly benefit dynamic modelling, analysis, and health monitoring of structures. For example, spatially high-density mode shapes are critical for accurate vibration-based damage localization. In experimental or operational modal analysis, higher (frequency) modes, which may be outside the frequency range of the measurement, contain local structural features that can improve damage localization as well as the construction and updating of the modal-based dynamic model of the structure. In general, the resolution of vibration measurements can be increased by enhanced hardware. Traditional vibration measurement sensors such as accelerometers have high-frequency sampling capacity; however, they are discrete point-wise sensors only providing sparse, low spatial sensing resolution measurements, while dense deployment to achieve high spatial resolution is expensive and results in the mass-loading effect and modification of structure's surface. Non-contact measurement methods such as scanning laser vibrometers provide high spatial and temporal resolution sensing capacity; however, they make measurements sequentially that requires considerable acquisition time. As an alternative non-contact method, digital video cameras are relatively low-cost, agile, and provide high spatial resolution, simultaneous, measurements. Combined with vision based algorithms (e.g., image correlation or template matching, optical flow, etc.), video camera based measurements have been successfully used for experimental and operational vibration measurement and subsequent modal analysis. However, the sampling frequency of most affordable digital cameras is limited to 30-60 Hz, while high-speed cameras for higher frequency vibration measurements are extremely costly. This work develops a computational algorithm capable of performing vibration measurement at a uniform sampling frequency lower than what is required by the Shannon-Nyquist sampling theorem for output-only modal analysis. In particular, the spatio-temporal uncoupling property of the modal expansion of structural vibration responses enables a direct modal decoupling of the temporally-aliased vibration measurements by existing output-only modal analysis methods, yielding (full-field) mode shapes estimation directly. Then the signal aliasing properties in modal analysis is exploited to estimate the modal frequencies and damping ratios. The proposed method is validated by laboratory experiments where output-only modal identification is conducted on temporally-aliased acceleration responses and particularly the temporally-aliased video measurements of bench-scale structures, including a three-story building structure and a cantilever beam.

Cross-cultural validity of a dietary questionnaire for studies of dental caries risk in Japanese.

PubMed

Shinga-Ishihara, Chikako; Nakai, Yukie; Milgrom, Peter; Murakami, Kaori; Matsumoto-Nakano, Michiyo

2014-01-02

Diet is a major modifiable contributing factor in the etiology of dental caries. The purpose of this paper is to examine the reliability and cross-cultural validity of the Japanese version of the Food Frequency Questionnaire to assess dietary intake in relation to dental caries risk in Japanese. The 38-item Food Frequency Questionnaire, in which Japanese food items were added to increase content validity, was translated into Japanese, and administered to two samples. The first sample comprised 355 pregnant women with mean age of 29.2 ± 4.2 years for the internal consistency and criterion validity analyses. Factor analysis (principal components with Varimax rotation) was used to determine dimensionality. The dietary cariogenicity score was calculated from the Food Frequency Questionnaire and used for the analyses. Salivary mutans streptococci level was used as a semi-quantitative assessment of dental caries risk and measured by Dentocult SM. Dentocult SM scores were compared with the dietary cariogenicity score computed from the Food Frequency Questionnaire to examine criterion validity, and assessed by Spearman's correlation coefficient (rs) and Kruskal-Wallis test. Test-retest reliability of the Food Frequency Questionnaire was assessed with a second sample of 25 adults with mean age of 34.0 ± 3.0 years by using the intraclass correlation coefficient analysis. The Japanese language version of the Food Frequency Questionnaire showed high test-retest reliability (ICC = 0.70) and good criterion validity assessed by relationship with salivary mutans streptococci levels (rs = 0.22; p < 0.001). Factor analysis revealed four subscales that construct the questionnaire (solid sugars, solid and starchy sugars, liquid and semisolid sugars, sticky and slowly dissolving sugars). Internal consistency were low to acceptable (Cronbach's alpha = 0.67 for the total scale, 0.46-0.61 for each subscale). Mean dietary cariogenicity scores were 50.8 ± 19.5 in the first sample, 47.4 ± 14.1, and 40.6 ± 11.3 for the first and second administrations in the second sample. The distribution of Dentocult SM score was 6.8% (score = 0), 34.4% (score = 1), 39.4% (score = 2), and 19.4% (score = 3). Participants with higher scores were more likely to have higher dietary cariogenicity scores (p < 0.001; Kruskal-Wallis test). These results provide the preliminary evidence for the reliability and validity of the Japanese language Food Frequency Questionnaire.

Efficacy of the detection of Legionella in hot and cold water samples by culture and PCR. II. Examination of native samples from various sources.

PubMed

Stojek, Nimfa Maria; Wójcik-Fatla, Angelina; Dutkiewicz, Jacek

2012-01-01

A total of 123 water samples were examined in parallel by culture and semi-nested PCR for the presence of Legionella. They comprised: 35 samples of hot water distributed by the urban municipal water supply system (MWSS) taken in institutions, 45 samples of hot water distributed by urban MWSS taken in dwellings, 27 samples of cold water distributed by rural MWSS taken in dwellings, and 16 samples of cold well water taken in rural areas. The greatest frequency of the isolation of Legionella by culture (88.6%) was recorded in the samples of hot water from the urban institutions, having been greater compared to all other sources (p<0.001). The frequency of Legionella isolation from hot water in urban dwellings (28.9%) was significantly greater compared to the combined value (2.3%) for cold water from rural MWSS and wells (p<0.001). Strains belonging to Legionella pneumophila serogroups 2-14 predominated in the examined samples, while strains of L. pneumophila serogroup 1 and strains of Legionella spp. (other than L. pneumophila) were 3-fold less numerous. The rates of positive findings in the semi-nested PCR (stage 2) were greater than culture isolations in all kinds of samples, except for urban institutions. The correlation between the culture and PCR results was positive for samples of hot water from urban MWSS (p<0.01), but not for samples of cold water from rural MWSS and wells (p>0.5). A significant correlation was found between rates of PCR-positive results and numbers of Legionella pneumophila serogroups 2-14 strains, but not for other Legionella serogroups or species. In conclusion, our results support the opinion that though PCR cannot be a substitute for the isolation of Legionella by culture, it could be regarded as an useful complementary method.

Trends in darunavir resistance-associated mutations and phenotypic resistance in commercially tested United States clinical samples between 2006 and 2012.

PubMed

Lathouwers, Erkki; Gupta, Soumi; Haddad, Mojgan; Paquet, Agnes; de Meyer, Sandra; Baugh, Bryan

2015-06-01

HIV-1 samples submitted by clinicians from the United States for routine drug susceptibility testing (PhenoSense GT) were evaluated for genotypic and phenotypic resistance to darunavir and other protease inhibitors (PIs). Among these samples (Monogram Biosciences database January 2006-June 2012; N=78,843), isolates harboring zero IAS-USA darunavir resistance-associated mutations (RAMs) increased from 77.7% in 2006 to 92.8% through the first half of 2012 (H1 2012; upward trend, p=0.0008); a downward trend seen for samples with three or more darunavir RAMs (7.5% in 2006 and 2.6% in H1 2012; p=0.002). Among samples with any PI resistance (N=15,932), samples harboring zero darunavir RAMs gradually increased (39.9% in 2006 vs. 55.0% in H1 2012; upward trend, p=0.005), but three or more darunavir RAMs did not change over time (21.7% in 2006 and 19.2% in H1 2012; p=0.27). During this period, the frequency of the 11 individual darunavir RAMs (IAS-USA 2011 list) decreased among all samples. The frequency of each darunavir RAM in PI-resistant samples decreased or remained relatively stable. The prevalence of samples with phenotypic resistance to darunavir (partial-to-full) decreased over time in all samples (8.2% in 2006 vs. 2.3% in H1 2012), as did resistance to other PIs (p<0.006 for all PIs). Phenotypic resistance to darunavir and other PIs also decreased in PI-resistant samples (darunavir: 23.9% in 2006 vs. 17.1% in H1 2012; p<0.013 for all PIs). Since approval of darunavir in 2006, there was a significant decrease in prevalence of samples with genotypic and phenotypic resistance to darunavir in commercially tested HIV-1 isolates. Furthermore, the prevalence of phenotypic resistance to darunavir was lower than all other PIs.

Dense home-based recordings reveal typical and atypical development of tense/aspect in a child with delayed language development.

PubMed

Chin, Iris; Goodwin, Matthew S; Vosoughi, Soroush; Roy, Deb; Naigles, Letitia R

2018-01-01

Studies investigating the development of tense/aspect in children with developmental disorders have focused on production frequency and/or relied on short spontaneous speech samples. How children with developmental disorders use future forms/constructions is also unknown. The current study expands this literature by examining frequency, consistency, and productivity of past, present, and future usage, using the Speechome Recorder, which enables collection of dense, longitudinal audio-video recordings of children's speech. Samples were collected longitudinally in a child who was previously diagnosed with autism spectrum disorder, but at the time of the study exhibited only language delay [Audrey], and a typically developing child [Cleo]. While Audrey was comparable to Cleo in frequency and productivity of tense/aspect use, she was atypical in her consistency and production of an unattested future form. Examining additional measures of densely collected speech samples may reveal subtle atypicalities that are missed when relying on only few typical measures of acquisition.

The theory of reasoned action in prediction of breast self-examination: a comparison of two studies.

PubMed

Powell-Cope, G M; Lierman, L M; Kasprzyk, D; Young, H M; Benoliel, J Q

1991-01-01

The purpose of this article is to report the application of the theory of reasoned action (TRA) to predict breast self-examination (BSE) intention and frequency in two studies with middle-aged and older women. The sample in Study 1 consisted of 93 volunteers from church groups; the second sample consisted of 175 randomly selected subscribers to a large health maintenance organization. Questionnaires to measure attitudinal and subjective normative influences relevant to BSE were developed using guidelines specified by Ajzen and Fishbein (1980). The attitudinal components predicted BSE intention in both studies and BSE frequency in Study 1. In contrast, the subjective norm contributed significantly only to the prediction of frequency in Study 1. Findings demonstrate varying degrees of success for the TRA in predicting BSE intention and behavior. Explanations for the inconsistency in the predictive ability of the TRA can be related to differences between the two studies regarding sample and design characteristics.

Electrical properties of lunar soil sample 15301,38

NASA Technical Reports Server (NTRS)

Olhoeft, G. R.; Frisillo, A. L.; Strangway, D. W.

1974-01-01

Electrical property measurements have been made on an Apollo 15 lunar soil sample in ultrahigh vacuum from room temperature to 827 C for the frequency spectrum from 100 Hz through 1 MHz. The dielectric constant, the total ac loss tangent, and the dc conductivity were measured. The dc conductivity showed no thermal hysteresis, but an irreversible (in vacuum) thermal effect was found in the dielectric loss tangent on heating above 700 C and during the subsequent cooling. This appears to be related to several effects associated with lunar glass above 700 C. The sample also showed characteristic low-frequency dispersion in the dielectric constant with increasing temperature, presumably due to Maxwell-Wagner intergranular effects. The dielectric properties may be fitted to a model involving a Cole-Cole frequency distribution that is relatively temperature-independent below 200 C and follows a Boltzmann temperature distribution with an activation energy of 2.5 eV above 200 C. The dc conductivity is fitted by an exponential temperature distribution and becomes the dominant loss above 700 C.

Structural, dielectric and magnetic properties of NiFe2O4 prepared via sol-gel auto-combustion method

NASA Astrophysics Data System (ADS)

Sun, Li; Zhang, Ru; Wang, Zhenduo; Ju, Lin; Cao, Ensi; Zhang, Yongjia

2017-01-01

Nickelferrite (NiFe2O4)powders were synthesized via sol-gel auto-combustion method and the corresponding temperature dependence of microstructure, dielectric and magnetic properties have been investigated. Results of XRD and SEM indicate that the NiFe2O4 samples exhibit a typical single phase spinel structure and a uniform particle distribution. The dielectric constant and dielectric loss measurements show strong frequency dependence of all the samples. The peak observed in frequency dependence of dielectric loss measurements shifts to higher frequency with the increasing sintering temperature, indicating a Debye-like dielectric relaxation. The remanent magnetization increases with the increasing grain size while the coercivity is just the opposite. The saturation magnetization can achieve 50 emu/g when the sintering temperature is more than 1000 °C, and the lowest coercivity (159.49 Oe) was observed in the NFO sample sintered at 1300 °C for 2 h.

Photoacoustic signal and noise analysis for Si thin plate: signal correction in frequency domain.

PubMed

Markushev, D D; Rabasović, M D; Todorović, D M; Galović, S; Bialkowski, S E

2015-03-01

Methods for photoacoustic signal measurement, rectification, and analysis for 85 μm thin Si samples in the 20-20 000 Hz modulation frequency range are presented. Methods for frequency-dependent amplitude and phase signal rectification in the presence of coherent and incoherent noise as well as distortion due to microphone characteristics are presented. Signal correction is accomplished using inverse system response functions deduced by comparing real to ideal signals for a sample with well-known bulk parameters and dimensions. The system response is a piece-wise construction, each component being due to a particular effect of the measurement system. Heat transfer and elastic effects are modeled using standard Rosencweig-Gersho and elastic-bending theories. Thermal diffusion, thermoelastic, and plasmaelastic signal components are calculated and compared to measurements. The differences between theory and experiment are used to detect and correct signal distortion and to determine detector and sound-card characteristics. Corrected signal analysis is found to faithfully reflect known sample parameters.

Optimal space communications techniques. [all digital phase locked loop for FM demodulation

NASA Technical Reports Server (NTRS)

Schilling, D. L.

1973-01-01

The design, development, and analysis are reported of a digital phase-locked loop (DPLL) for FM demodulation and threshold extension. One of the features of the developed DPLL is its synchronous, real time operation. The sampling frequency is constant and all the required arithmetic and logic operations are performed within one sampling period, generating an output sequence which is converted to analog form and filtered. An equation relating the sampling frequency to the carrier frequency must be satisfied to guarantee proper DPLL operation. The synchronous operation enables a time-shared operation of one DPLL to demodulate several FM signals simultaneously. In order to obtain information about the DPLL performance at low input signal-to-noise ratios, a model of an input noise spike was introduced, and the DPLL equation was solved using a digital computer. The spike model was successful in finding a second order DPLL which yielded a five db threshold extension beyond that of a first order DPLL.

Spanish adaptation of social withdrawal motivation and frequency scales.

PubMed

Indias García, Sílvia; De Paúl Ochotorena, Joaquín

2016-11-01

To adapt into Spanish three scales measuring frequency (SWFS) and motivation for social withdrawal (CSPS and SWMS) and to develop a scale capable of assessing the five motivations for social withdrawal. Participants were 1,112 Spanish adolescents, aged 12-17 years. The sample was randomly split into two groups in which exploratory and confirmatory (CFA) factor analyses were performed separately. A sample of adolescents in residential care (n = 128) was also used to perform discriminant validity analyses. SWFS was reduced to eight items that account for 40% of explained variance (PVE), and its reliability is high. SWMS worked adequately in the original version, according to CFA. Some items from the CSPS were removed from the final Spanish version. The newly developed scale (SWMS-5D) is composed of 20 items including five subscales: Peer Isolation, Unsociability, Shyness, Low Mood and Avoidance. Analyses reveal adequate convergent and discriminant validities. The resulting SWFS-8 and SWMS-5D could be considered useful instruments to assess frequency and motivation for social withdrawal in Spanish samples.

Prevalence of Pre-Analytical Errors in Clinical Chemistry Diagnostic Labs in Sulaimani City of Iraqi Kurdistan

PubMed Central

2017-01-01

Background Laboratory testing is roughly divided into three phases: a pre-analytical phase, an analytical phase and a post-analytical phase. Most analytical errors have been attributed to the analytical phase. However, recent studies have shown that up to 70% of analytical errors reflect the pre-analytical phase. The pre-analytical phase comprises all processes from the time a laboratory request is made by a physician until the specimen is analyzed at the lab. Generally, the pre-analytical phase includes patient preparation, specimen transportation, specimen collection and storage. In the present study, we report the first comprehensive assessment of the frequency and types of pre-analytical errors at the Sulaimani diagnostic labs in Iraqi Kurdistan. Materials and Methods Over 2 months, 5500 venous blood samples were observed in 10 public diagnostic labs of Sulaimani City. The percentages of rejected samples and types of sample inappropriateness were evaluated. The percentage of each of the following pre-analytical errors were recorded: delay in sample transportation, clotted samples, expired reagents, hemolyzed samples, samples not on ice, incorrect sample identification, insufficient sample, tube broken in centrifuge, request procedure errors, sample mix-ups, communication conflicts, misinterpreted orders, lipemic samples, contaminated samples and missed physician’s request orders. The difference between the relative frequencies of errors observed in the hospitals considered was tested using a proportional Z test. In particular, the survey aimed to discover whether analytical errors were recorded and examine the types of platforms used in the selected diagnostic labs. Results The analysis showed a high prevalence of improper sample handling during the pre-analytical phase. In appropriate samples, the percentage error was as high as 39%. The major reasons for rejection were hemolyzed samples (9%), incorrect sample identification (8%) and clotted samples (6%). Most quality control schemes at Sulaimani hospitals focus only on the analytical phase, and none of the pre-analytical errors were recorded. Interestingly, none of the labs were internationally accredited; therefore, corrective actions are needed at these hospitals to ensure better health outcomes. Internal and External Quality Assessment Schemes (EQAS) for the pre-analytical phase at Sulaimani clinical laboratories should be implemented at public hospitals. Furthermore, lab personnel, particularly phlebotomists, need continuous training on the importance of sample quality to obtain accurate test results. PMID:28107395

Prevalence of Pre-Analytical Errors in Clinical Chemistry Diagnostic Labs in Sulaimani City of Iraqi Kurdistan.

PubMed

Najat, Dereen

2017-01-01

Laboratory testing is roughly divided into three phases: a pre-analytical phase, an analytical phase and a post-analytical phase. Most analytical errors have been attributed to the analytical phase. However, recent studies have shown that up to 70% of analytical errors reflect the pre-analytical phase. The pre-analytical phase comprises all processes from the time a laboratory request is made by a physician until the specimen is analyzed at the lab. Generally, the pre-analytical phase includes patient preparation, specimen transportation, specimen collection and storage. In the present study, we report the first comprehensive assessment of the frequency and types of pre-analytical errors at the Sulaimani diagnostic labs in Iraqi Kurdistan. Over 2 months, 5500 venous blood samples were observed in 10 public diagnostic labs of Sulaimani City. The percentages of rejected samples and types of sample inappropriateness were evaluated. The percentage of each of the following pre-analytical errors were recorded: delay in sample transportation, clotted samples, expired reagents, hemolyzed samples, samples not on ice, incorrect sample identification, insufficient sample, tube broken in centrifuge, request procedure errors, sample mix-ups, communication conflicts, misinterpreted orders, lipemic samples, contaminated samples and missed physician's request orders. The difference between the relative frequencies of errors observed in the hospitals considered was tested using a proportional Z test. In particular, the survey aimed to discover whether analytical errors were recorded and examine the types of platforms used in the selected diagnostic labs. The analysis showed a high prevalence of improper sample handling during the pre-analytical phase. In appropriate samples, the percentage error was as high as 39%. The major reasons for rejection were hemolyzed samples (9%), incorrect sample identification (8%) and clotted samples (6%). Most quality control schemes at Sulaimani hospitals focus only on the analytical phase, and none of the pre-analytical errors were recorded. Interestingly, none of the labs were internationally accredited; therefore, corrective actions are needed at these hospitals to ensure better health outcomes. Internal and External Quality Assessment Schemes (EQAS) for the pre-analytical phase at Sulaimani clinical laboratories should be implemented at public hospitals. Furthermore, lab personnel, particularly phlebotomists, need continuous training on the importance of sample quality to obtain accurate test results.

Herbs and brush on California red fir regeneration sites: a species and frequency sampling

Treesearch

Donald T. Gordon; Eugene E. Bowen

1978-01-01

In a sampling of 32 logged areas in red fir forests of northern California, 58 plant species were found. Species corresponded with less than one-fifth of the 93 species reported in an earlier study of the virgin forest. Sampling of uncut areas adjacent to cuttings does not seem useful for predicting the earlier successional vegetation that will appear when the areas...

Time-Domain Nuclear Magnetic Resonance (TD-NMR) and Chemometrics for Determination of Fat Content in Commercial Products of Milk Powder.

PubMed

Nascimento, Paloma Andrade Martins; Barsanelli, Paulo Lopes; Rebellato, Ana Paula; Pallone, Juliana Azevedo Lima; Colnago, Luiz Alberto; Pereira, Fabíola Manhas Verbi

2017-03-01

This study shows the use of time-domain (TD)-NMR transverse relaxation (T2) data and chemometrics in the nondestructive determination of fat content for powdered food samples such as commercial dried milk products. Most proposed NMR spectroscopy methods for measuring fat content correlate free induction decay or echo intensities with the sample's mass. The need for the sample's mass limits the analytical frequency of NMR determination, because weighing the samples is an additional step in this procedure. Therefore, the method proposed here is based on a multivariate model of T2 decay, measured with Carr-Purcell-Meiboom-Gill pulse sequence and reference values of fat content. The TD-NMR spectroscopy method shows high correlation (r = 0.95) with the lipid content, determined by the standard extraction method of Bligh and Dyer. For comparison, fat content determination was also performed using a multivariate model with near-IR (NIR) spectroscopy, which is also a nondestructive method. The advantages of the proposed TD-NMR method are that it (1) minimizes toxic residue generation, (2) performs measurements with high analytical frequency (a few seconds per analysis), and (3) does not require sample preparation (such as pelleting, needed for NIR spectroscopy analyses) or weighing the samples.

Statistical analysis of environmental monitoring data: does a worst case time for monitoring clean rooms exist?

PubMed

Cundell, A M; Bean, R; Massimore, L; Maier, C

1998-01-01

To determine the relationship between the sampling time of the environmental monitoring, i.e., viable counts, in aseptic filling areas and the microbial count and frequency of alerts for air, surface and personnel microbial monitoring, statistical analyses were conducted on 1) the frequency of alerts versus the time of day for routine environmental sampling conducted in calendar year 1994, and 2) environmental monitoring data collected at 30-minute intervals during routine aseptic filling operations over two separate days in four different clean rooms with multiple shifts and equipment set-ups at a parenteral manufacturing facility. Statistical analyses showed, except for one floor location that had significantly higher number of counts but no alert or action level samplings in the first two hours of operation, there was no relationship between the number of counts and the time of sampling. Further studies over a 30-day period at the floor location showed no relationship between time of sampling and microbial counts. The conclusion reached in the study was that there is no worst case time for environmental monitoring at that facility and that sampling any time during the aseptic filling operation will give a satisfactory measure of the microbial cleanliness in the clean room during the set-up and aseptic filling operation.

Monitoring survey of the use patterns and pesticide residues on vegetables in the Niayes zone, Senegal.

PubMed

Diop, Amadou; Diop, Yérim M; Thiaré, Diène D; Cazier, Fabrice; Sarr, Serigne O; Kasprowiak, Amaury; Landy, David; Delattre, François

2016-02-01

The main objective of this work was to determine the impact of pesticide use practices on vegetables contamination in the Niayes zone of Dakar. A preliminary survey involving 200 farmers, showed the application of pesticides belonging to different groups on vegetable crops. Use practices in terms of application intervals and methods, measuring tools and dosage were not in compliance with good agricultural practices. In view of survey results, investigations on vegetable contamination were conducted. Therefore, 175 vegetable samples including cabbage (31 samples), lettuce (88 samples), tomato (57 samples) collected from four sites of the Niayes zone during four campaigns, were analyzed for residues of 21 pesticides, eighteen of which (18) were cited to be used by farmers. The results indicated that 65% of tomato samples, 71% of lettuce and 93% of cabbage contained one or more detectable residues. Among the monitored pesticides dicofol, chlorpyrifos, DDTs, dimethoate, and λ-cyhalothrin were the most predominant, found in at least 35% of samples for each vegetable. The frequencies of pesticide detection were, generally in agreement with the citation frequencies. The results provided important information on vegetable contamination status and pointed an urgent need to control pesticide use. Copyright © 2015. Published by Elsevier Ltd.

Identifiability and Performance Analysis of Output Over-sampling Approach to Direct Closed-loop Identification

NASA Astrophysics Data System (ADS)

Sun, Lianming; Sano, Akira

Output over-sampling based closed-loop identification algorithm is investigated in this paper. Some instinct properties of the continuous stochastic noise and the plant input, output in the over-sampling approach are analyzed, and they are used to demonstrate the identifiability in the over-sampling approach and to evaluate its identification performance. Furthermore, the selection of plant model order, the asymptotic variance of estimated parameters and the asymptotic variance of frequency response of the estimated model are also explored. It shows that the over-sampling approach can guarantee the identifiability and improve the performance of closed-loop identification greatly.

Effect of non-Poisson samples on turbulence spectra from laser velocimetry

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

Sree, D.; Kjelgaard, S.O.; Sellers, W.L. III

1994-12-01

Spectral estimations from LV data are typically based on the assumption of a Poisson sampling process. It is demonstrated here that the sampling distribution must be considered before spectral estimates are used to infer turbulence scales. A non-Poisson sampling process can occur if there is nonhomogeneous distribution of particles in the flow. Based on the study of a simulated first-order spectrum, it has been shown that a non-Poisson sampling process causes the estimated spectrum to deviate from the true spectrum. Also, in this case the prefiltering techniques do not improve the spectral estimates at higher frequencies. 4 refs.

Dielectric and magnetic studies of Cr+3 doped nickel ferrite by combustion method

NASA Astrophysics Data System (ADS)

Parveez, Asiya; Shekhawat, M. S.; Sindhu, S.; Srikanth, C.; Nayeem, Firdous; Mohd. Shariff, S.; Sinha, R. R.; Chaudhuri, Arka; Khader, S. Abdul

2018-05-01

Cr+3 doped nickel ferrite nanoparticles having the basic composition NiCrxFe2-xO4 (x=0, 0.1, 0.15, 0.2, 1) were prepared using auto combustion method. Structural, dielectric, a.c conductivity and magnetic properties of these samples, which are sintered at 800°C were studied. The structures of the synthesized samples were probed by X-ray diffraction (XRD) studies. The peaks observed in the XRD spectrum indicated single phase spinel cubic structure for the synthesized samples. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM). The dielectric constant (ɛ') and dielectric loss factor (ɛ″) of nanocrystalline nickel ferrites were investigated as a function of frequency and Cr+3 concentration at room temperature over the frequency range 100 Hz to 1 MHz using Hioki make LCR Hi-Tester 3250. The dependence of ɛ' and ɛ″ with the frequency of the alternating applied electric field is in accordance with the Maxwell-Wagner type interfacial polarization, which is in agreement with the Koop's theory. The electrical conductivity (σac) deduced from the measured dielectric data has been thoroughly analyzed and found that the conduction mechanism in NiCrxFe2-xO4 nanoferrites are in conformity with the electron hopping model. The magnetic properties of Cr+3 doped nano-nickel ferrite were analyzed using a Vibrating Sample Magnetometer (VSM). It is observed that the values of saturation magnetization decreases along with the increase in chromium content.

Extreme assay sensitivity in molecular diagnostics further unveils intratumour heterogeneity in metastatic colorectal cancer as well as artifactual low-frequency mutations in the KRAS gene.

PubMed

Mariani, Sara; Bertero, Luca; Osella-Abate, Simona; Di Bello, Cristiana; Francia di Celle, Paola; Coppola, Vittoria; Sapino, Anna; Cassoni, Paola; Marchiò, Caterina

2017-07-25

Gene mutations in the RAS family rule out metastatic colorectal carcinomas (mCRCs) from anti-EGFR therapies. We report a retrospective analysis by Sequenom Massarray and fast COLD-PCR followed by Sanger sequencing on 240 mCRCs. By Sequenom, KRAS and NRAS exons 2-3-4 were mutated in 52.9% (127/240) of tumours, while BRAF codon 600 mutations reached 5% (12/240). Fast COLD-PCR found extra mutations at KRAS exon 2 in 15/166 (9%) of samples, previously diagnosed by Sequenom as wild-type or mutated at RAS (exons 3-4) or BRAF genes. After UDG digestion results were reproduced in 2/12 analysable subclonally mutated samples leading to a frequency of true subclonal KRAS mutations of 1.2% (2.1% of the previous Sequenom wild-type subgroup). In 10 out of 12 samples, the subclonal KRAS mutations disappeared (9 out of 12) or turned to a different sequence variant (1 out of 12). mCRC can harbour coexisting multiple gene mutations. High sensitivity assays allow the detection of a small subset of patients harbouring true subclonal KRAS mutations. However, DNA changes with mutant allele frequencies <3% detected in formalin-fixed paraffin-embedded samples may be artifactual in a non-negligible fraction of cases. UDG pre-treatment of DNA is mandatory to identify true DNA changes in archival samples and avoid misinterpretation due to artifacts.

Extreme assay sensitivity in molecular diagnostics further unveils intratumour heterogeneity in metastatic colorectal cancer as well as artifactual low-frequency mutations in the KRAS gene

PubMed Central

Mariani, Sara; Bertero, Luca; Osella-Abate, Simona; Di Bello, Cristiana; Francia di Celle, Paola; Coppola, Vittoria; Sapino, Anna; Cassoni, Paola; Marchiò, Caterina

2017-01-01

Background: Gene mutations in the RAS family rule out metastatic colorectal carcinomas (mCRCs) from anti-EGFR therapies. Methods: We report a retrospective analysis by Sequenom Massarray and fast COLD-PCR followed by Sanger sequencing on 240 mCRCs. Results: By Sequenom, KRAS and NRAS exons 2-3-4 were mutated in 52.9% (127/240) of tumours, while BRAF codon 600 mutations reached 5% (12/240). Fast COLD-PCR found extra mutations at KRAS exon 2 in 15/166 (9%) of samples, previously diagnosed by Sequenom as wild-type or mutated at RAS (exons 3-4) or BRAF genes. After UDG digestion results were reproduced in 2/12 analysable subclonally mutated samples leading to a frequency of true subclonal KRAS mutations of 1.2% (2.1% of the previous Sequenom wild-type subgroup). In 10 out of 12 samples, the subclonal KRAS mutations disappeared (9 out of 12) or turned to a different sequence variant (1 out of 12). Conclusions: mCRC can harbour coexisting multiple gene mutations. High sensitivity assays allow the detection of a small subset of patients harbouring true subclonal KRAS mutations. However, DNA changes with mutant allele frequencies <3% detected in formalin-fixed paraffin-embedded samples may be artifactual in a non-negligible fraction of cases. UDG pre-treatment of DNA is mandatory to identify true DNA changes in archival samples and avoid misinterpretation due to artifacts. PMID:28618430

Optimizing liquid effluent monitoring at a large nuclear complex.

PubMed

Chou, Charissa J; Barnett, D Brent; Johnson, Vernon G; Olson, Phil M

2003-12-01

Effluent monitoring typically requires a large number of analytes and samples during the initial or startup phase of a facility. Once a baseline is established, the analyte list and sampling frequency may be reduced. Although there is a large body of literature relevant to the initial design, few, if any, published papers exist on updating established effluent monitoring programs. This paper statistically evaluates four years of baseline data to optimize the liquid effluent monitoring efficiency of a centralized waste treatment and disposal facility at a large defense nuclear complex. Specific objectives were to: (1) assess temporal variability in analyte concentrations, (2) determine operational factors contributing to waste stream variability, (3) assess the probability of exceeding permit limits, and (4) streamline the sampling and analysis regime. Results indicated that the probability of exceeding permit limits was one in a million under normal facility operating conditions, sampling frequency could be reduced, and several analytes could be eliminated. Furthermore, indicators such as gross alpha and gross beta measurements could be used in lieu of more expensive specific isotopic analyses (radium, cesium-137, and strontium-90) for routine monitoring. Study results were used by the state regulatory agency to modify monitoring requirements for a new discharge permit, resulting in an annual cost savings of US dollars 223,000. This case study demonstrates that statistical evaluation of effluent contaminant variability coupled with process knowledge can help plant managers and regulators streamline analyte lists and sampling frequencies based on detection history and environmental risk.

Synthesis, electrical and magnetic properties of sodium borosilicate glasses containing Co-ferrites nanoparticles

NASA Astrophysics Data System (ADS)

Othman, H. A.; Eltabey, M. M.; Ibrahim, Samia. E.; El-Deen, L. M. Sharaf; Elkholy, M. M.

2017-02-01

Co-ferrites nanoparticles that have been prepared by the co-precipitation method were added to sodium borosilicate (Na2O-B2O3-SiO2) glass matrix by the solid solution method and they were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and magnetization measurements. (XRD) revealed the formation of the Co-ferrite magnetic crystalline phase embedded in an amorphous matrix in all the samples. The investigated samples by (TEM) showed the formation of the cobalt ferrite nanoparticles with a spherical shape and highly monodispersed with an average size about 13 nm. IR data revealed that the BO3 and BO4 are the main structural units of these samples network. IR spectra of the investigated samples showed the characteristic vibration bands of Co-ferrite. Composition and frequency dependent dielectric properties of the prepared samples were measured at room temperature in the frequency range 100-100 kHz. The conductivity was found to increase with increasing cobalt ferrite content. The variations of conductivity and dielectric properties with frequency and composition were discussed. Magnetic hysteresis loops were traced at room temperature using VSM and values of saturation magnetization MS and coercive field HC were determined. The obtained results revealed that a ferrimagnetic behavior were observed and as Co-ferrite concentration increases the values of MS and HC increase from 2.84 to 8.79 (emu/g) and from 88.4 to 736.3 Oe, respectively.

Some physical properties of Apollo 12 lunar samples

NASA Technical Reports Server (NTRS)

Gold, T.; Oleary, B. T.; Campbell, M.

1971-01-01

The size distribution of the lunar fines is measured, and small but significant differences are found between the Apollo 11 and 12 samples as well as among the Apollo 12 core samples. The observed differences in grain size distribtuion in the core samples are related to surface transportation processes, and the importance of a sedimentation process versus meteoritic impact gardening of the mare grounds is discussed. The optical and the radio frequency electrical properties are measured and are also found to differ only slightly from Apollo 11 results.

A careful look at ECG sampling frequency and R-peak interpolation on short-term measures of heart rate variability.

PubMed

Ellis, Robert J; Zhu, Bilei; Koenig, Julian; Thayer, Julian F; Wang, Ye

2015-09-01

As the literature on heart rate variability (HRV) continues to burgeon, so too do the challenges faced with comparing results across studies conducted under different recording conditions and analysis options. Two important methodological considerations are (1) what sampling frequency (SF) to use when digitizing the electrocardiogram (ECG), and (2) whether to interpolate an ECG to enhance the accuracy of R-peak detection. Although specific recommendations have been offered on both points, the evidence used to support them can be seen to possess a number of methodological limitations. The present study takes a new and careful look at how SF influences 24 widely used time- and frequency-domain measures of HRV through the use of a Monte Carlo-based analysis of false positive rates (FPRs) associated with two-sample tests on independent sets of healthy subjects. HRV values from the first sample were calculated at 1000 Hz, and HRV values from the second sample were calculated at progressively lower SFs (and either with or without R-peak interpolation). When R-peak interpolation was applied prior to HRV calculation, FPRs for all HRV measures remained very close to 0.05 (i.e. the theoretically expected value), even when the second sample had an SF well below 100 Hz. Without R-peak interpolation, all HRV measures held their expected FPR down to 125 Hz (and far lower, in the case of some measures). These results provide concrete insights into the statistical validity of comparing datasets obtained at (potentially) very different SFs; comparisons which are particularly relevant for the domains of meta-analysis and mobile health.

High frequency monitoring of pesticides in runoff water to improve understanding of their transport and environmental impacts.

PubMed

Lefrancq, Marie; Jadas-Hécart, Alain; La Jeunesse, Isabelle; Landry, David; Payraudeau, Sylvain

2017-06-01

Rainfall-induced peaks in pesticide concentrations can occur rapidly. Low frequency sampling may therefore largely underestimate maximum pesticide concentrations and fluxes. Detailed storm-based sampling of pesticide concentrations in runoff water to better predict pesticide sources, transport pathways and toxicity within the headwater catchments is lacking. High frequency monitoring (2min) of seven pesticides (Dimetomorph, Fluopicolide, Glyphosate, Iprovalicarb, Tebuconazole, Tetraconazole and Triadimenol) and one degradation product (AMPA) were assessed for 20 runoff events from 2009 to 2012 at the outlet of a vineyard catchment in the Layon catchment in France. The maximum pesticide concentrations were 387μgL -1 . Samples from all of the runoff events exceeded the legal limit of 0.1μgL -1 for at least one pesticide (European directive 2013/39/EC). High resolution sampling used to detect the peak pesticide levels revealed that Toxic Units (TU) for algae, invertebrates and fish often exceeded the European Uniform principles (25%). The point and average (time or discharge-weighted) concentrations indicated up to a 30- or 4-fold underestimation of the TU obtained when measuring the maximum concentrations, respectively. This highlights the important role of sampling methods for assessing peak exposure. High resolution sampling combined with concentration-discharge hysteresis analyses revealed that clockwise responses were predominant (52%), indicating that Hortonian runoff is the prevailing surface runoff trigger mechanism in the study catchment. The hysteresis patterns for suspended solids and pesticides were highly dynamic and storm- and chemical-dependent. Intense rainfall events induced stronger C-Q hysteresis (magnitude). This study provides new insights into the complexity of pesticide dynamics in runoff water and highlights the ability of hysteresis analysis to improve understanding of pesticide supply and transport. Copyright © 2017 Elsevier B.V. All rights reserved.

Magnetic induction spectroscopy: non-contact measurement of the electrical conductivity spectra of biological samples

NASA Astrophysics Data System (ADS)

Barai, A.; Watson, S.; Griffiths, H.; Patz, R.

2012-08-01

Measurement of the electrical conductivity of biological tissues as a function of frequency, often termed ‘bioelectrical impedance spectroscopy (BIS)’, provides valuable information on tissue structure and composition. In implementing BIS though, there can be significant practical difficulties arising from the electrode-sample interface which have likely limited its deployment in industrial applications. In magnetic induction spectroscopy (MIS) these difficulties are eliminated through the use of fully non-contacting inductive coupling between the sensors and sample. However, inductive coupling introduces its own set of technical difficulties, primarily related to the small magnitudes of the induced currents and their proportionality with frequency. This paper describes the design of a practical MIS system incorporating new, highly-phase-stable electronics and compares its performance with that of electrode-based BIS in measurements on biological samples including yeast suspensions in saline (concentration 50-400 g l-1) and solid samples of potato, cucumber, tomato, banana and porcine liver. The shapes of the MIS spectra were in good agreement with those for electrode-based BIS, with a residual maximum discrepancy of 28%. The measurement precision of the MIS was 0.05 S m-1 at 200 kHz, improving to 0.01 S m-1 at a frequency of 20 MHz, for a sample volume of 80 ml. The data-acquisition time for each MIS measurement was 52 s. Given the value of spectroscopic conductivity information and the many advantages of obtaining these data in a non-contacting manner, even through electrically-insulating packaging materials if necessary, it is concluded that MIS is a technique with considerable potential for monitoring bio-industrial processes and product quality.

Across-plane thermal characterization of films based on amplitude-frequency profile in photothermal technique

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

Xu, Shen; Wang, Xinwei, E-mail: xwang3@iastate.edu

2014-10-15

This work develops an amplitude method for the photothermal (PT) technique to analyze the amplitude of the thermal radiation signal from the surface of a multilayered film sample. The thermal conductivity of any individual layer in the sample can be thereby determined. Chemical vapor deposited SiC film samples (sample 1 to 3: 2.5 to 3.5 μm thickness) with different ratios of Si to C and thermally oxidized SiO{sub 2} film (500 nm thickness) on silicon substrates are studied using the amplitude method. The determined thermal conductivity based on the amplitude method is 3.58, 3.59, and 2.59 W/m⋅K for sample 1more » to 3 with ±10% uncertainty. These results are verified by the phase shift method, and sound agreement is obtained. The measured thermal conductivity (k) of SiC is much lower than the value of bulk SiC. The large k reduction is caused by the structure difference revealed by Raman spectroscopy. For the SiO{sub 2} film, the thermal conductivity is measured to be 1.68 ± 0.17 W/m⋅K, a little higher than that obtained by the phase shift method: 1.31 ± 0.06 W/m⋅K. Sensitivity analysis of thermal conductivity and interfacial resistance is conducted for the amplitude method. Its weak-sensitivity to the thermal contact resistance, enables the amplitude method to determine the thermal conductivity of a film sample with little effect from the interface thermal resistance between the film and substrate. The normalized amplitude ratio at a high frequency to that at a low frequency provides a reliable way to evaluate the effusivity ratio of the film to that of the substrate.« less

Modulation of flyash-induced genotoxicity in Vicia faba by vermicomposting.

PubMed

Jain, Kavindra; Singh, Jitendra; Chauhan, L K S; Murthy, R C; Gupta, S K

2004-09-01

Cytogenetic effects of pre- and postvermicomposted flyash samples were evaluated on the root meristem cells of Vicia faba. Seedlings of V. faba were directly sown in flyash and cow dung-soil mixtures (20%, 40%, 60%, and 80%) and the lateral roots grown in these test mixtures were sampled at 5 days. Negative control was run parallel in cow dung-soil (CS) mixture alone. One set of flyash-cow dung-soil (FCS) mixture was subjected to vermicomposting by introducing Eisenia foetida species of earthworms for 30 days and the cytogenetic effects were reinvestigated through V. faba root meristems. Chemical analysis carried out prior to vermicomposting revealed high concentrations of heavy metals such as Cr, Cu, Pb, Zn, and Ni in FCS samples. CS samples also showed the presence of these metals. Cytogenetic examinations of root meristems exposed to the FCS mixtures showed significant inhibition of mitotic index (MI), induction of chromosome aberrations (CA), and a significantly increased frequency of mitotic aberrations (MA). The increase of the aberrations was dependent on the flyash concentrations. Roots grown in CS samples also showed chromosomal and MAs; however, the percentage was lower than that observed with FCS and also statistically nonsignificant. Cytogenetic analysis of vermicomposted samples of FCS revealed a 15-45% decline in the aberration frequencies whereas chemical analysis showed a 10-50% decline in the metal concentrations, viz. Cr, Cu, Pb, Zn, and Ni, which indicates E. foetida a potential accumulator of heavy metals and the decline in metal concentrations may be the cause of the decrease in aberration frequencies. The present study indicates the genotoxicity potential of flyash and also the feasibility of vermicomposting for cleanup of metal-contaminated soil to mitigate the toxicity/genotoxicity. Copyright 2004 Elsevier Inc.

Sample treatment optimization for fish stool metabolomics.

PubMed

Hano, Takeshi; Ito, Mana; Ito, Katsutoshi; Uchida, Motoharu

2018-06-07

Gut microbiota play an essential role in an organism's health. The fecal metabolite profiling content reflects these microbiota-mediated physiological changes in various organisms, including fish. Therefore, metabolomics analysis of fish feces should provide insight into the dynamics linking physiology and gut microbiota. However, metabolites are often unstable in aquatic environments, making fecal metabolites difficult to examine in fish. In this study, a novel method using gas chromatography-mass spectrometry (GC-MS) was developed and optimized for the preparation of metabolomics samples from the feces of the marine fish, red sea bream (Pagrus major). The preparation methodology was optimized, focusing on rinsing frequency and rinsing solvent. Feces (collected within 4 h of excretion) were rinsed three times with sterilized 2.5% NaCl solution or 3.0% artificial seawater (ASW). Among the 86 metabolites identified in the NaCl-rinsed samples, 57 showed superior recovery to that in ASW-rinsed samples, indicating that NaCl is a better rinsing solvent, particularly for amino acids, organic acids, and fatty acids. To evaluate rinsing frequency, fecal samples were rinsed with NaCl solution 0, 1, 3, or 5 times. The results indicate that three or more rinses enabled robust and stable detection of metabolites encapsulated within the solid fecal residue. Furthermore, these data suggest that rinsing is unnecessary when studying sugars, amino acids, and sterols, again highlighting the need for appropriate rinsing solvent and frequency. This study provides further insight into the use of fecal samples to evaluate and promote fish health during farming and supports the application of this and similar analyses to study the effects of environmental fluctuations and/or contamination. Copyright © 2018 Elsevier B.V. All rights reserved.

Emergent HIV-1 Drug Resistance Mutations Were Not Present at Low-Frequency at Baseline in Non-Nucleoside Reverse Transcriptase Inhibitor-Treated Subjects in the STaR Study

PubMed Central

Porter, Danielle P.; Daeumer, Martin; Thielen, Alexander; Chang, Silvia; Martin, Ross; Cohen, Cal; Miller, Michael D.; White, Kirsten L.

2015-01-01

At Week 96 of the Single-Tablet Regimen (STaR) study, more treatment-naïve subjects that received rilpivirine/emtricitabine/tenofovir DF (RPV/FTC/TDF) developed resistance mutations compared to those treated with efavirenz (EFV)/FTC/TDF by population sequencing. Furthermore, more RPV/FTC/TDF-treated subjects with baseline HIV-1 RNA >100,000 copies/mL developed resistance compared to subjects with baseline HIV-1 RNA ≤100,000 copies/mL. Here, deep sequencing was utilized to assess the presence of pre-existing low-frequency variants in subjects with and without resistance development in the STaR study. Deep sequencing (Illumina MiSeq) was performed on baseline and virologic failure samples for all subjects analyzed for resistance by population sequencing during the clinical study (n = 33), as well as baseline samples from control subjects with virologic response (n = 118). Primary NRTI or NNRTI drug resistance mutations present at low frequency (≥2% to 20%) were detected in 6.6% of baseline samples by deep sequencing, all of which occurred in control subjects. Deep sequencing results were generally consistent with population sequencing but detected additional primary NNRTI and NRTI resistance mutations at virologic failure in seven samples. HIV-1 drug resistance mutations emerging while on RPV/FTC/TDF or EFV/FTC/TDF treatment were not present at low frequency at baseline in the STaR study. PMID:26690199

Emergent HIV-1 Drug Resistance Mutations Were Not Present at Low-Frequency at Baseline in Non-Nucleoside Reverse Transcriptase Inhibitor-Treated Subjects in the STaR Study.

PubMed

Porter, Danielle P; Daeumer, Martin; Thielen, Alexander; Chang, Silvia; Martin, Ross; Cohen, Cal; Miller, Michael D; White, Kirsten L

2015-12-07

At Week 96 of the Single-Tablet Regimen (STaR) study, more treatment-naïve subjects that received rilpivirine/emtricitabine/tenofovir DF (RPV/FTC/TDF) developed resistance mutations compared to those treated with efavirenz (EFV)/FTC/TDF by population sequencing. Furthermore, more RPV/FTC/TDF-treated subjects with baseline HIV-1 RNA >100,000 copies/mL developed resistance compared to subjects with baseline HIV-1 RNA ≤100,000 copies/mL. Here, deep sequencing was utilized to assess the presence of pre-existing low-frequency variants in subjects with and without resistance development in the STaR study. Deep sequencing (Illumina MiSeq) was performed on baseline and virologic failure samples for all subjects analyzed for resistance by population sequencing during the clinical study (n = 33), as well as baseline samples from control subjects with virologic response (n = 118). Primary NRTI or NNRTI drug resistance mutations present at low frequency (≥2% to 20%) were detected in 6.6% of baseline samples by deep sequencing, all of which occurred in control subjects. Deep sequencing results were generally consistent with population sequencing but detected additional primary NNRTI and NRTI resistance mutations at virologic failure in seven samples. HIV-1 drug resistance mutations emerging while on RPV/FTC/TDF or EFV/FTC/TDF treatment were not present at low frequency at baseline in the STaR study.

Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

NASA Astrophysics Data System (ADS)

Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

2018-01-01

Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, "sub-sampling training examples"-based and "manipulating input features"-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

Comprehensive analysis of structure and temperature, frequency and concentration-dependent dielectric properties of lithium-substituted cobalt ferrites (Li x Co1- x Fe2O4)

NASA Astrophysics Data System (ADS)

Anjum, Safia; Nisa, Mehru; Sabah, Aneeqa; Rafique, M. S.; Zia, Rehana

2017-08-01

This paper has been dedicated to the synthesis and characterization of a series of lithium-substituted cobalt ferrites Li x Co1- x Fe2O4 ( x = 0, 0.2, 0.4, 0.6, 0.8, 1). These samples have been prepared using simple ball milling machine through powder metallurgy route. The structural analysis is carried out using X-ray diffractometer and their 3D vitalization is simulated using diamond software. The frequency and temperature-dependent dielectric properties of prepared samples have been measured using inductor capacitor resistor (LCR) meter. The structural analysis confirms that all the prepared samples have inverse cubic spinel structure. It is also revealed that the crystallite size and lattice parameter decrease with the increasing concentration of lithium (Li+1) ions, it is due to the smaller ionic radii of lithium ions. The comprehensive analysis of frequency, concentration and temperature-dependent dielectric properties of prepared samples is described in this paper. It is observed that the dielectric constant and tangent loss have decreased and conductivity increased as the frequency increases. It is also revealed that the dielectric constant, tangent loss and AC conductivity increase as the concentration of lithium increases due to its lower electronegativity value. Temperature plays a vital role in enhancing the dielectric constant, tangent loss and AC conductivity because the mobility of ions increases as the temperature increases.

Sampling modulation technique in radio-frequency helium glow discharge emission source by use of pulsed laser ablation.

PubMed

Naeem, Tariq Mahmood; Matsuta, Hideyuki; Wagatsuma, Kazuaki

2004-05-01

An emission excitation source comprising a high-frequency diode-pumped Q-switched Nd:YAG laser and a radio-frequency powered glow discharge lamp is proposed. In this system sample atoms ablated by the laser irradiation are introduced into the lamp chamber and subsequently excited by the helium glow discharge plasma. The pulsed operation of the laser can produce a cyclic variation in the emission intensities of the sample atoms whereas the plasma gas species emit the radiation continuously. The salient feature of the proposed technique is the selective detection of the laser modulation signal from the rest of the continuous background emissions, which can be achieved with the phase sensitive detection of the lock-in amplifier. The arrangement may be used to estimate the emission intensity of the laser ablated atom, free from the interference of other species present in the plasma. The experiments were conducted with a 13.56 MHz radio-frequency (rf) generator operated at 80 W power to produce plasma and the laser at a wavelength of 1064 nm (pulse duration:34 ns, repetition rate:7 kHz and average pulse energy of about 0.36 mJ) was employed for sample ablation. The measurements resulted in almost complete removal of nitrogen molecular bands (N(2)(+) 391.44 nm). Considerable reduction (about 75%) in the emission intensity of a carbon atomic line (C I 193.03 nm) was also observed.

Dispersion of Dielectric Permittivity in a Nanocrystalline Cellulose-Triglycine Sulfate Composite at Low and Ultralow Frequencies

NASA Astrophysics Data System (ADS)

Thu'o'ng, Nguyen Hoai; Sidorkin, A. S.; Milovidova, S. D.

2018-03-01

The dispersion of dielectric permittivity in nanocrystalline cellulose-triglycine sulfate composites is studied in the range of frequencies from 10-3 to 106 Hz, at temperatures varying from room temperature to the temperature of phase transition in this composite (54°C), in weak electric fields (1 V cm-1). Two behaviors for the dielectric dispersion are identified in the studied frequency range: at ultralow frequencies (10-3-10 Hz), the dispersion is due to Maxwell-Wagner polarization, while at higher frequencies (10-106 Hz), the dispersion is due to the movement of domain walls in the embedded triglycine sulfate crystallites. An additional peak in the temperature-dependent profiles of dielectric permittivity is detected at lower temperatures in freshly prepared samples of the considered composite; we associate it with the presence of residual water in these samples.

The effect of sampling rate and anti-aliasing filters on high-frequency response spectra

USGS Publications Warehouse

Boore, David M.; Goulet, Christine

2013-01-01

The most commonly used intensity measure in ground-motion prediction equations is the pseudo-absolute response spectral acceleration (PSA), for response periods from 0.01 to 10 s (or frequencies from 0.1 to 100 Hz). PSAs are often derived from recorded ground motions, and these motions are usually filtered to remove high and low frequencies before the PSAs are computed. In this article we are only concerned with the removal of high frequencies. In modern digital recordings, this filtering corresponds at least to an anti-aliasing filter applied before conversion to digital values. Additional high-cut filtering is sometimes applied both to digital and to analog records to reduce high-frequency noise. Potential errors on the short-period (high-frequency) response spectral values are expected if the true ground motion has significant energy at frequencies above that of the anti-aliasing filter. This is especially important for areas where the instrumental sample rate and the associated anti-aliasing filter corner frequency (above which significant energy in the time series is removed) are low relative to the frequencies contained in the true ground motions. A ground-motion simulation study was conducted to investigate these effects and to develop guidance for defining the usable bandwidth for high-frequency PSA. The primary conclusion is that if the ratio of the maximum Fourier acceleration spectrum (FAS) to the FAS at a frequency fsaa corresponding to the start of the anti-aliasing filter is more than about 10, then PSA for frequencies above fsaa should be little affected by the recording process, because the ground-motion frequencies that control the response spectra will be less than fsaa . A second topic of this article concerns the resampling of the digital acceleration time series to a higher sample rate often used in the computation of short-period PSA. We confirm previous findings that sinc-function interpolation is preferred to the standard practice of using linear time interpolation for the resamplin

Effect of multi-walled carbon nanotubes aspect ratio and temperature on the dielectric behavior of alternating alkene-carbon monoxide polyketone nanocomposites

NASA Astrophysics Data System (ADS)

Abu-Surrah, Adnan S.; Abdul Jawad, Saadi; Al-Ramahi, Esraa; Hallak, Awni B.; Khattari, Z.

2015-04-01

New alternating poly(propylene-alt-carbon monoxide/ethylene-alt-carbon monoxide) (PECO)/multiwalled carbon nanotubes (MWCNTs) composites have been prepared. Dielectric permittivity, electric modulus and ac conductivity of the isolated materials were investigated as a function of fiber aspect ratio, frequency and temperature. For aspect ratio of 30 and 200, a transition from insulator to semiconductor was observed at frequency 1×104. However, for high aspect ratio sample (660), no transition was observed and the conductivity is frequency independent in the measured frequency range of 10-106 Hz. The conductivity increases from about 1×10-4 for the sample that contain fibers of aspect ratio 30 and reaches 5×10-2 (Ω m)-1 for aspect ratio was 660. This behavior can be modeled by a circuit that consists of a contact resistance in series with a parallel combination of resistance (R) and capacitance (C). The calculated activation energy for sample filled with fibers having aspect ratio 30 is about 0.26 eV and decreases to about 0.16 eV when the aspect ratio is 660.

Measuring Dynamic Signals with Direct Sensor-to-Microcontroller Interfaces Applied to a Magnetoresistive Sensor

PubMed Central

Sifuentes, Ernesto; Gonzalez-Landaeta, Rafael; Cota-Ruiz, Juan; Reverter, Ferran

2017-01-01

This paper evaluates the performance of direct interface circuits (DIC), where the sensor is directly connected to a microcontroller, when a resistive sensor subjected to dynamic changes is measured. The theoretical analysis provides guidelines for the selection of the components taking into account both the desired resolution and the bandwidth of the input signal. Such an analysis reveals that there is a trade-off between the sampling frequency and the resolution of the measurement, and this depends on the selected value of the capacitor that forms the RC circuit together with the sensor resistance. This performance is then experimentally proved with a DIC measuring a magnetoresistive sensor exposed to a magnetic field of different frequencies, amplitudes, and waveforms. A sinusoidal magnetic field up to 1 kHz can be monitored with a resolution of eight bits and a sampling frequency of around 10 kSa/s. If a higher resolution is desired, the sampling frequency has to be lower, thus limiting the bandwidth of the dynamic signal under measurement. The DIC is also applied to measure an electrocardiogram-type signal and its QRS complex is well identified, which enables the estimation, for instance, of the heart rate. PMID:28524078

Measuring Dynamic Signals with Direct Sensor-to-Microcontroller Interfaces Applied to a Magnetoresistive Sensor.

PubMed

Sifuentes, Ernesto; Gonzalez-Landaeta, Rafael; Cota-Ruiz, Juan; Reverter, Ferran

2017-05-18

This paper evaluates the performance of direct interface circuits (DIC), where the sensor is directly connected to a microcontroller, when a resistive sensor subjected to dynamic changes is measured. The theoretical analysis provides guidelines for the selection of the components taking into account both the desired resolution and the bandwidth of the input signal. Such an analysis reveals that there is a trade-off between the sampling frequency and the resolution of the measurement, and this depends on the selected value of the capacitor that forms the RC circuit together with the sensor resistance. This performance is then experimentally proved with a DIC measuring a magnetoresistive sensor exposed to a magnetic field of different frequencies, amplitudes, and waveforms. A sinusoidal magnetic field up to 1 kHz can be monitored with a resolution of eight bits and a sampling frequency of around 10 kSa/s. If a higher resolution is desired, the sampling frequency has to be lower, thus limiting the bandwidth of the dynamic signal under measurement. The DIC is also applied to measure an electrocardiogram-type signal and its QRS complex is well identified, which enables the estimation, for instance, of the heart rate.

Thermal conductivity of nanocrystalline silicon: importance of grain size and frequency-dependent mean free paths.

PubMed

Wang, Zhaojie; Alaniz, Joseph E; Jang, Wanyoung; Garay, Javier E; Dames, Chris

2011-06-08

The thermal conductivity reduction due to grain boundary scattering is widely interpreted using a scattering length assumed equal to the grain size and independent of the phonon frequency (gray). To assess these assumptions and decouple the contributions of porosity and grain size, five samples of undoped nanocrystalline silicon have been measured with average grain sizes ranging from 550 to 64 nm and porosities from 17% to less than 1%, at temperatures from 310 to 16 K. The samples were prepared using current activated, pressure assisted densification (CAPAD). At low temperature the thermal conductivities of all samples show a T(2) dependence which cannot be explained by any traditional gray model. The measurements are explained over the entire temperature range by a new frequency-dependent model in which the mean free path for grain boundary scattering is inversely proportional to the phonon frequency, which is shown to be consistent with asymptotic analysis of atomistic simulations from the literature. In all cases the recommended boundary scattering length is smaller than the average grain size. These results should prove useful for the integration of nanocrystalline materials in devices such as advanced thermoelectrics.

Evaluation of the Compulsive Exercise Test (CET) in Adolescents with Eating Disorders: Factor Structure and Relation to Eating Disordered Psychopathology.

PubMed

Swenne, Ingemar

2016-07-01

The aims of this study were to explore the factor structure of the Compulsive Exercise Test (CET) in a clinical sample of Swedish adolescents with eating disorders (ED) and to study the relationship of CET with ED cognitions, body weight and exercise frequency. The compulsive Exercise Test, the Eating Disorders Examination-Questionnaire, body mass index (BMI) and exercise frequency were available at assessment of 210 adolescents (age 14.4 ± 1.6 years) with ED. Factor analysis generated four factors with close similarity to factors previously obtained in a community sample of adolescents samples and supported the use of the original version of CET. Exercise for weight control was strongly related to ED cognitions but less to exercise frequency and BMI. Exercise for regulation of mood was related to ED cognitions and exercise frequency but not to BMI. In adolescents with ED, different aspects of exercise are related to ED cognitions. This needs addressing in the treatment of adolescents with ED. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

Conductivity tomography based on pulsed eddy current with SQUID magnetometer

NASA Astrophysics Data System (ADS)

Panaitov, G. I.; Krause, H.-J.; Zhang, Y.

2002-05-01

Pulsed eddy current (EC) techniques have the advantage of potentially covering a broader depth range than standard single frequency EC testing. We developed a novel pulsed EC technique using a liquid-nitrogen cooled SQUID magnetometer. For two reasons, SQUID magnetometers are particularly well suited as sensors: first they constitute an extremely sensitive magnetic field sensor, second they measure the field directly which decays more slowly than its time derivative picked up by induction coils. A square waveform transmitter signal was used, with alternating slopes in order to eliminate drift effect, and stacking synchronous to the power line frequency in order to improve signal-to-noise. The early time (high frequency) data of the recorded transient correspond to the upper layers of the conducting medium, while late time data or low frequencies deliver information on deep layers. Measurements of cracks at different depths in a stacked aluminum sample are presented. From the measured data, the apparent conductivity of the sample was calculated for each position and depth by applying a technique known from geophysical data interpretation. Thus, the position and depth of the crack was determined from the tomographic conductivity image of the sample.

Apparatus and method for measuring minority carrier lifetimes in semiconductor materials

DOEpatents

Ahrenkiel, Richard K.; Johnston, Steven W.

2001-01-01

An apparatus for determining the minority carrier lifetime of a semiconductor sample includes a positioner for moving the sample relative to a coil. The coil is connected to a bridge circuit such that the impedance of one arm of the bridge circuit is varied as sample is positioned relative to the coil. The sample is positioned relative to the coil such that any change in the photoconductance of the sample created by illumination of the sample creates a linearly related change in the input impedance of the bridge circuit. In addition, the apparatus is calibrated to work at a fixed frequency so that the apparatus maintains a consistently high sensitivity and high linearity for samples of different sizes, shapes, and material properties. When a light source illuminates the sample, the impedance of the bridge circuit is altered as excess carriers are generated in the sample, thereby producing a measurable signal indicative of the minority carrier lifetimes or recombination rates of the sample.

Apparatus for measuring minority carrier lifetimes in semiconductor materials

DOEpatents

Ahrenkiel, R.K.

1999-07-27

An apparatus for determining the minority carrier lifetime of a semiconductor sample includes a positioner for moving the sample relative to a coil. The coil is connected to a bridge circuit such that the impedance of one arm of the bridge circuit is varied as sample is positioned relative to the coil. The sample is positioned relative to the coil such that any change in the photoconductance of the sample created by illumination of the sample creates a linearly related change in the input impedance of the bridge circuit. In addition, the apparatus is calibrated to work at a fixed frequency so that the apparatus maintains a consistently high sensitivity and high linearly for samples of different sizes, shapes, and material properties. When a light source illuminates the sample, the impedance of the bridge circuit is altered as excess carriers are generated in the sample, thereby producing a measurable signal indicative of the minority carrier lifetimes or recombination rates of the sample. 17 figs.

Apparatus for measuring minority carrier lifetimes in semiconductor materials

DOEpatents

Ahrenkiel, Richard K.

1999-01-01

An apparatus for determining the minority carrier lifetime of a semiconductor sample includes a positioner for moving the sample relative to a coil. The coil is connected to a bridge circuit such that the impedance of one arm of the bridge circuit is varied as sample is positioned relative to the coil. The sample is positioned relative to the coil such that any change in the photoconductance of the sample created by illumination of the sample creates a linearly related change in the input impedance of the bridge circuit. In addition, the apparatus is calibrated to work at a fixed frequency so that the apparatus maintains a consistently high sensitivity and high linearly for samples of different sizes, shapes, and material properties. When a light source illuminates the sample, the impedance of the bridge circuit is altered as excess carriers are generated in the sample, thereby producing a measurable signal indicative of the minority carrier lifetimes or recombination rates of the sample.

Using known map category marginal frequencies to improve estimates of thematic map accuracy

NASA Technical Reports Server (NTRS)

Card, D. H.

1982-01-01

By means of two simple sampling plans suggested in the accuracy-assessment literature, it is shown how one can use knowledge of map-category relative sizes to improve estimates of various probabilities. The fact that maximum likelihood estimates of cell probabilities for the simple random sampling and map category-stratified sampling were identical has permitted a unified treatment of the contingency-table analysis. A rigorous analysis of the effect of sampling independently within map categories is made possible by results for the stratified case. It is noted that such matters as optimal sample size selection for the achievement of a desired level of precision in various estimators are irrelevant, since the estimators derived are valid irrespective of how sample sizes are chosen.

Frequency of Pathogenic Paediatric Bacterial Meningitis in Mozambique: The Critical Role of Multiplex Real-Time Polymerase Chain Reaction to Estimate the Burden of Disease.

PubMed

Nhantumbo, Aquino Albino; Cantarelli, Vlademir Vicente; Caireão, Juliana; Munguambe, Alcides Moniz; Comé, Charlotte Elizabeth; Pinto, Gabriela do Carmo; Zimba, Tomás Francisco; Mandomando, Inácio; Semá, Cynthia Baltazar; Dias, Cícero; Moraes, Milton Ozório; Gudo, Eduardo Samo

2015-01-01

In Sub-Saharan Africa, including Mozambique, acute bacterial meningitis (ABM) represents a main cause of childhood mortality. The burden of ABM is seriously underestimated because of the poor performance of culture sampling, the primary method of ABM surveillance in the region. Low quality cerebrospinal fluid (CSF) samples and frequent consumption of antibiotics prior to sample collection lead to a high rate of false-negative results. To our knowledge, this study is the first to determine the frequency of ABM in Mozambique using real-time polymerase chain reaction (qPCR) and to compare results to those of culture sampling. Between March 2013 and March 2014, CSF samples were collected at 3 regional hospitals from patients under 5 years of age, who met World Health Organization case definition criteria for ABM. Macroscopic examination, cytochemical study, culture, and qPCR were performed on all samples. A total of 369 CSF samples were collected from children clinically suspected of ABM. qPCR showed a significantly higher detection rate of ABM-causing pathogens when compared to culture (52.3% [193/369] versus 7.3% [27/369], p = 0.000). The frequency of Streptococcus pneumoniae, Haemophilus influenzae, group B Streptococci, and Neisseria meningitidis were 32.8% (121⁄369), 12.2%, (45⁄369), 3.0% (16⁄369) and 4.3% (11⁄369), respectively, significantly higher compared to that obtained on culture (p < 0.001 for each). Our findings demonstrate that culture is less effective for the diagnosis of ABM than qPCR. The common use of culture rather than qPCR to identify ABM results in serious underestimation of the burden of the disease, and our findings strongly suggest that qPCR should be incorporated into surveillance activities for ABM. In addition, our data showed that S. pneumoniae represents the most common cause of ABM in children under 5 years of age.

Nightmare frequency in adults with attention-deficit hyperactivity disorder.

PubMed

Schredl, Michael; Bumb, J Malte; Alm, Barbara; Sobanski, Esther

2017-02-01

Nightmare frequency in adult ADHD patients has not yet been studied systematically. In a sample of 65 patients, it could be shown that nightmare frequency was elevated in ADHD patients compared to a sample representative for Germany. Frequent nightmares (once a week or more often) were reported by 4.62 % of the patients and 1.77 % of the controls. This increase was neither explained by the increased dream recall in general nor by the presence of a comorbid mental disorder. Questions about nightmares should be included in the diagnostic procedures for ADHD patients, and it should be tested whether well-established nightmare treatment strategies like imagery rehearsal treatment might be beneficial to those patients with nightmares.

Multi-Mode Excitation and Data Reduction for Fatigue Crack Characterization in Conducting Plates

NASA Technical Reports Server (NTRS)

Wincheski, B.; Namkung, M.; Fulton, J. P.; Clendenin, C. G.

1992-01-01

Advances in the technique of fatigue crack characterization by resonant modal analysis have been achieved through a new excitation mechanism and data reduction of multiple resonance modes. A non-contacting electromagnetic device is used to apply a time varying Lorentz force to thin conducting sheets. The frequency and direction of the Lorentz force are such that resonance modes are generated in the test sample. By comparing the change in frequency between distinct resonant modes of a sample, detecting and sizing of fatigue cracks are achieved and frequency shifts caused by boundary condition changes can be discriminated against. Finite element modeling has been performed to verify experimental results.

Short communication: Microbiological quality of raw cow milk and its association with herd management practices in Northern China.

PubMed

Lan, X Y; Zhao, S G; Zheng, N; Li, S L; Zhang, Y D; Liu, H M; McKillip, J; Wang, J Q

2017-06-01

Contamination of raw milk with bacterial pathogens is potentially hazardous to human health. The aim of this study was to evaluate the total bacteria count (TBC) and presence of pathogens in raw milk in Northern China along with the associated herd management practices. A total of 160 raw milk samples were collected from 80 dairy herds in Northern China. All raw milk samples were analyzed for TBC and pathogens by culturing. The results showed that the number of raw milk samples with TBC <2 × 10 6 cfu/mL and <1 × 10 5 cfu/mL was 146 (91.25%) and 70 (43.75%), respectively. A total of 84 (52.50%) raw milk samples were Staphylococcus aureus positive, 72 (45.00%) were Escherichia coli positive, 2 (1.25%) were Salmonella positive, 2 (1.25%) were Listeria monocytogenes positive, and 3 (1.88%) were Campylobacter positive. The prevalence of S. aureus was influenced by season, herd size, milking frequency, disinfection frequency, and use of a Dairy Herd Improvement program. The TBC was influenced by season and milk frequency. The correlation between TBC and prevalence of S. aureus or E. coli is significant. The effect size statistical analysis showed that season and herd (but not Dairy Herd Improvement, herd size, milking frequency, disinfection frequency, and area) were the most important factors affecting TBC in raw milk. In conclusion, the presence of bacteria in raw milk was associated with season and herd management practices, and further comprehensive study will be powerful for effectively characterizing various factors affecting milk microbial quality in bulk tanks in China. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Human genetic selection on the MTHFR 677C>T polymorphism

PubMed Central

Mayor-Olea, Álvaro; Callejón, Gonzalo; Palomares, Arturo R; Jiménez, Ana J; Gaitán, María Jesús; Rodríguez, Alfonso; Ruiz, Maximiliano; Reyes-Engel, Armando

2008-01-01

Background The prevalence of genotypes of the 677C>T polymorphism for the MTHFR gene varies among humans. In previous studies, we found changes in the genotypic frequencies of this polymorphism in populations of different ages, suggesting that this could be caused by an increase in the intake of folate and multivitamins by women during the periconceptional period. The aim was to analyze changes in the allelic frequencies of this polymorphism in a Spanish population, including samples from spontaneous abortions (SA). Methods A total of 1305 subjects born in the 20th century were genotyped for the 677C>T polymorphism using allele specific real-time PCR with Taqman® probes. A section of our population (n = 276) born in 1980–1989 was compared with fetal samples (n = 344) from SA of unknown etiology from the same period. Results An increase in the frequency of the T allele (0.38 vs 0.47; p < 0.001) and of the TT genotype (0.14 vs 0.24; p < 0.001) in subjects born in the last quarter of the century was observed. In the 1980–1989 period, the results show that the frequency of the wild type genotype (CC) is about tenfold lower in the SA samples than in the controls (0.03 vs 0.33; p < 0.001) and that the frequency of the TT genotype increases in the controls (0.19 to 0.27) and in the SA samples (0.20 to 0.33 (p < 0.01)); r = 0.98. Conclusion Selection in favor of the T allele has been detected. This selection could be due to the increased fetal viability in early stages of embryonic development, as is deduced by the increase of mutants in both living and SA populations. PMID:19040733

Enhanced detection of thiophenol adsorbed on gold nanoparticles by SFG and DFG nonlinear optical spectroscopy.

PubMed

Pluchery, Olivier; Humbert, Christophe; Valamanesh, Mehrnoush; Lacaze, Emmanuelle; Busson, Bertrand

2009-09-21

Sum frequency generation (SFG) and difference frequency generation (DFG) are applied to study vibrational resonance of the thiophenol molecule adsorbed on two different gold samples. One sample is made of 17 nm gold nanoparticles (AuNPs) fixed on a silicon substrate that has been previously functionalized with a silane monolayer (aminopropyltriethoxysilane, APTES). This sample is fully characterized through visible reflection spectroscopy and AFM. The second sample is a gold monocrystal also covered with thiophenol molecules. From their comparison, an enhancement factor of 21 is deduced for the SFG signal on AuNPs with respect to the Au(111), related to the surface plasmon resonance (SPR). From a combined analysis of the SFG and DFG spectra, we demonstrate that SFG/DFG spectroscopy is able to identify the nature of the substrate where the molecules are adsorbed. This opens new perspectives for this nonlinear spectroscopy by adding to its well-known intrinsic surface specificity, the ability to selectively probe the chemical layer capping the AuNPs.

Temporally flickering nanoparticles for compound cellular imaging and super resolution

NASA Astrophysics Data System (ADS)

Ilovitsh, Tali; Danan, Yossef; Meir, Rinat; Meiri, Amihai; Zalevsky, Zeev

2016-03-01

This work presents the use of flickering nanoparticles for imaging biological samples. The method has high noise immunity, and it enables the detection of overlapping types of GNPs, at significantly sub-diffraction distances, making it attractive for super resolving localization microscopy techniques. The method utilizes a lock-in technique at which the imaging of the sample is done using a time-modulated laser beam that match the number of the types of gold nanoparticles (GNPs) that label a given sample, and resulting in the excitation of the temporal flickering of the scattered light at known temporal frequencies. The final image where the GNPs are spatially separated is obtained using post processing where the proper spectral components corresponding to the different modulation frequencies are extracted. This allows the simultaneous super resolved imaging of multiple types of GNPs that label targets of interest within biological samples. Additionally applying the post-processing algorithm of the K-factor image decomposition algorithm can further improve the performance of the proposed approach.