Implications of High-Frequency Cochlear Dead Regions for Fitting Hearing Aids to Adults with Mild to Moderately-Severe Hearing Loss

PubMed Central

Cox, Robyn M.; Johnson, Jani A.; Alexander, Genevieve C.

2012-01-01

Short Summary It has been suggested that existence of high-frequency cochlear dead regions (DRs) has implications for hearing aid fitting, and that the optimal amount of high-frequency gain is reduced for these patients. This investigation used laboratory and field measurements to examine the effectiveness of reduced high-frequency gain in typical hearing aid users with high-frequency DRs. Both types of data revealed that speech understanding was better with the evidence-based prescription than with reduced high-frequency gain, and that this was seen for listeners with and without DRs. Nevertheless, subjects did not always prefer the amplification condition that produced better speech understanding. PMID:22555183

An experimental system for the study of active vibration control - Development and modeling

NASA Astrophysics Data System (ADS)

Batta, George R.; Chen, Anning

A modular rotational vibration system designed to facilitate the study of active control of vibrating systems is discussed. The model error associated with four common types of identification problems has been studied. The general multiplicative uncertainty shape for a vibration system is small in low frequencies, large at high frequencies. The frequency-domain error function has sharp peaks near the frequency of each mode. The inability to identify a high-frequency mode causes an increase of uncertainties at all frequencies. Missing a low-frequency mode causes the uncertainties to be much larger at all frequencies than missing a high-frequency mode. Hysteresis causes a small increase of uncertainty at low frequencies, but its overall effect is relatively small.

Spatial distribution of cold-season lightning frequency in the coastal areas of the Sea of Japan

NASA Astrophysics Data System (ADS)

Tsurushima, Daiki; Sakaida, Kiyotaka; Honma, Noriyasu

2017-12-01

The coastal areas of the Sea of Japan are a well-known hotspot of winter lightning activity. This study distinguishes between three common types of winter lightning in that region (types A-C), based on their frequency distributions and the meteorological conditions under which they occur. Type A lightning occurs with high frequency in the Tohoku district. It is mainly caused by cold fronts that accompany cyclones passing north of the Japanese islands. Type B, which occurs most frequently in the coastal areas of the Hokuriku district, is mainly caused by topographically induced wind convergence and convective instability, both of which are associated with cyclones having multiple centers. Type C's lightning frequency distribution pattern is similar to that of type B, but its principal cause is a topographically induced wind convergence generated by cold air advection from the Siberian continent. Type A is most frequently observed from October to November, while types B and C tend to appear from November to January, consistent with seasonal changes in lightning frequency distribution in Japan's Tohoku and Hokuriku districts.

BK potassium channels facilitate high-frequency firing and cause early spike frequency adaptation in rat CA1 hippocampal pyramidal cells

PubMed Central

Gu, Ning; Vervaeke, Koen; Storm, Johan F

2007-01-01

Neuronal potassium (K+) channels are usually regarded as largely inhibitory, i.e. reducing excitability. Here we show that BK-type calcium-activated K+ channels enhance high-frequency firing and cause early spike frequency adaptation in neurons. By combining slice electrophysiology and computational modelling, we investigated functions of BK channels in regulation of high-frequency firing in rat CA1 pyramidal cells. Blockade of BK channels by iberiotoxin (IbTX) selectively reduced the initial discharge frequency in response to strong depolarizing current injections, thus reducing the early spike frequency adaptation. IbTX also blocked the fast afterhyperpolarization (fAHP), slowed spike rise and decay, and elevated the spike threshold. Simulations with a computational model of a CA1 pyramidal cell confirmed that the BK channel-mediated rapid spike repolarization and fAHP limits activation of slower K+ channels (in particular the delayed rectifier potassium current (IDR)) and Na+ channel inactivation, whereas M-, sAHP- or SK-channels seem not to be important for the early facilitating effect. Since the BK current rapidly inactivates, its facilitating effect diminishes during the initial discharge, thus producing early spike frequency adaptation by an unconventional mechanism. This mechanism is highly frequency dependent. Thus, IbTX had virtually no effect at spike frequencies < 40 Hz. Furthermore, extracellular field recordings demonstrated (and model simulations supported) that BK channels contribute importantly to high-frequency burst firing in response to excitatory synaptic input to distal dendrites. These results strongly support the idea that BK channels play an important role for early high-frequency, rapidly adapting firing in hippocampal pyramidal neurons, thus promoting the type of bursting that is characteristic of these cells in vivo, during behaviour. PMID:17303637

Compact high voltage, high peak power, high frequency transformer for converter type modulator applications.

PubMed

Reghu, T; Mandloi, V; Shrivastava, Purushottam

2016-04-01

The design and development of a compact high voltage, high peak power, high frequency transformer for a converter type modulator of klystron amplifiers is presented. The transformer has been designed to operate at a frequency of 20 kHz and at a flux swing of ±0.6 T. Iron (Fe) based nanocrystalline material has been selected as a core for the construction of the transformer. The transformer employs a specially designed solid Teflon bobbin having 120 kV insulation for winding the high voltage secondary windings. The flux swing of the core has been experimentally found by plotting the hysteresis loop at actual operating conditions. Based on the design, a prototype transformer has been built which is per se a unique combination of high voltage, high frequency, and peak power specifications. The transformer was able to provide 58 kV (pk-pk) at the secondary with a peak power handling capability of 700 kVA. The transformation ratio was 1:17. The performance of the transformer is also presented and discussed.

Measurement of n-type Dry Thermally Oxidized 6H-SiC Metal-oxide Semiconductor Diodes by Quasistatic and High-Frequency Capacitance Versus Voltage and Capacitance Transient Techniques

NASA Technical Reports Server (NTRS)

Neudeck, P.; Kang, S.; Petit, J.; Tabib-Azar, M.

1994-01-01

Dry-oxidized n-type 6H-SiC metal-oxide-semiconductor capacitors are investigated using quasistatic capacitance versus voltage (C-V), high-frequency C-V, and pulsed high-frequency capacitance transient (C-t) analysis over the temperature range from 297 to 573 K. The quasistatic C - V characteristics presented are the first reported for 6H-SiC MOS capacitors, and exhibit startling nonidealities due to nonequilibrium conditions that arise from the fact that the recombination/generation process in 6H-SiC is extraordinarily slow even at the highest measurement temperature employed. The high-frequency dark C-V characteristics all showed deep depletion with no observable hysteresis. The recovery of the high-frequency capacitance from deep depletion to inversion was used to characterize the minority-carrier generation process as a function of temperature. Zerbst analysis conducted on the resulting C-t transients, which were longer than 1000 s at 573 K, showed a generation lifetime thermal activation energy of 0.49 eV.

Measuring Ambiguity in HLA Typing Methods

PubMed Central

Madbouly, Abeer; Freeman, John; Maiers, Martin

2012-01-01

In hematopoietic stem cell transplantation, donor selection is based primarily on matching donor and patient HLA genes. These genes are highly polymorphic and their typing can result in exact allele assignment at each gene (the resolution at which patients and donors are matched), but it can also result in a set of ambiguous assignments, depending on the typing methodology used. To facilitate rapid identification of matched donors, registries employ statistical algorithms to infer HLA alleles from ambiguous genotypes. Linkage disequilibrium information encapsulated in haplotype frequencies is used to facilitate prediction of the most likely haplotype assignment. An HLA typing with less ambiguity produces fewer high-probability haplotypes and a more reliable prediction. We estimated ambiguity for several HLA typing methods across four continental populations using an information theory-based measure, Shannon's entropy. We used allele and haplotype frequencies to calculate entropy for different sets of 1,000 subjects with simulated HLA typing. Using allele frequencies we calculated an average entropy in Caucasians of 1.65 for serology, 1.06 for allele family level, 0.49 for a 2002-era SSO kit, and 0.076 for single-pass SBT. When using haplotype frequencies in entropy calculations, we found average entropies of 0.72 for serology, 0.73 for allele family level, 0.05 for SSO, and 0.002 for single-pass SBT. Application of haplotype frequencies further reduces HLA typing ambiguity. We also estimated expected confirmatory typing mismatch rates for simulated subjects. In a hypothetical registry with all donors typed using the same method, the entropy values based on haplotype frequencies correspond to confirmatory typing mismatch rates of 1.31% for SSO versus only 0.08% for SBT. Intermediate-resolution single-pass SBT contains the least ambiguity of the methods we evaluated and therefore the most certainty in allele prediction. The presented measure objectively evaluates HLA typing methods and can help define acceptable HLA typing for donor recruitment. PMID:22952712

The frequency of HLA-B(∗)57:01 and the risk of abacavir hypersensitivity reactions in the majority population of Costa Rica.

PubMed

Arrieta-Bolaños, Esteban; Madrigal, J Alejandro; Marsh, Steven G E; Shaw, Bronwen E; Salazar-Sánchez, Lizbeth

2014-11-01

HLA-B(∗)57:01 is a well-known and cost-effective pharmacogenetic marker for abacavir hypersensitivity. As with other HLA alleles, there is widespread variation in its frequency across populations. The Costa Rica Central Valley Population (CCVP) is the major population in this country. The frequency of HLA-B(∗)57:01 in this population has not been described yet. Thus, our aim was to determine the frequency of this allele in the CCVP. 200 unrelated healthy volunteer donors born in the CCVP were typed. HLA-B(∗)57-positive samples identified by HLA intermediate resolution typing methods were further typed by SBT to high resolution. An HLA-B(∗)57:01 carrier frequency of 5.00% was determined in this sample. This frequency is relatively high in comparison to reports from other populations in Latin America. These results suggest that there is a considerable frequency of HLA-B(∗)57:01 in the CCVP and that pharmacogenetic testing for HIV+ patients who are going to receive abacavir-based treatment should be considered in this country. Copyright © 2014 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

A review of concepts regarding the origin of respiratory muscle fatigue

NASA Astrophysics Data System (ADS)

Kuraszkiewicz, Bożena; Piotrkiewicz, Maria

2011-01-01

In this review, the classification of respiratory muscle fatigue from the perspective of its origin is presented. The fatigue is classified as central or peripheral, and the latter further subdivided into high- and low-frequency fatigue. However, muscle fatigue is a complex process and all three types of fatigue probably occur simultaneously in the overloaded respiratory muscles. The relative importance of each type depends on the duration of respiratory loading and other physiological variables. However, central and high-frequency fatigue resolve rapidly once muscle overload is removed, whereas low-frequency fatigue persists over long time.

Principle and design of small-sized and high-definition x-ray machine

NASA Astrophysics Data System (ADS)

Zhao, Anqing

2010-10-01

The paper discusses the circuit design and working principles of VMOS PWM type 75KV10mA high frequency X-ray machine. The system mainly consists of silicon controlled rectifier, VMOS tube PWM type high-frequency and highvoltage inverter circuit, filament inverter circuit, high-voltage rectifier filter circuit and as X-ray tube. The working process can be carried out under the control of a single-chip microcomputer. Due to the small size and high resolution in imaging, the X-ray machine is mostly adopted for emergent medical diagnosis and specific circumstances where nondestructive tests are conducted.

Investigating strength and frequency effects in recognition memory using type-2 signal detection theory.

PubMed

Higham, Philip A; Perfect, Timothy J; Bruno, Davide

2009-01-01

Criterion- versus distribution-shift accounts of frequency and strength effects in recognition memory were investigated with Type-2 signal detection receiver operating characteristic (ROC) analysis, which provides a measure of metacognitive monitoring. Experiment 1 demonstrated a frequency-based mirror effect, with a higher hit rate and lower false alarm rate, for low frequency words compared with high frequency words. In Experiment 2, the authors manipulated item strength with repetition, which showed an increased hit rate but no effect on the false alarm rate. Whereas Type-1 indices were ambiguous as to whether these effects were based on a criterion- or distribution-shift model, the two models predict opposite effects on Type-2 distractor monitoring under some assumptions. Hence, Type-2 ROC analysis discriminated between potential models of recognition that could not be discriminated using Type-1 indices alone. In Experiment 3, the authors manipulated Type-1 response bias by varying the number of old versus new response categories to confirm the assumptions made in Experiments 1 and 2. The authors conclude that Type-2 analyses are a useful tool for investigating recognition memory when used in conjunction with more traditional Type-1 analyses.

Novel Cavities in Vertical External Cavity Surface Emitting Lasers for Emission in Broad Spectral Region by Means of Nonlinear Frequency Conversion

NASA Astrophysics Data System (ADS)

Lukowski, Michal L.

Optically pumped semiconductor vertical external cavity surface emitting lasers (VECSEL) were first demonstrated in the mid 1990's. Due to the unique design properties of extended cavity lasers VECSELs have been able to provide tunable, high-output powers while maintaining excellent beam quality. These features offer a wide range of possible applications in areas such as medicine, spectroscopy, defense, imaging, communications and entertainment. Nowadays, newly developed VECSELs, cover the spectral regions from red (600 nm) to around 5 microm. By taking the advantage of the open cavity design, the emission can be further expanded to UV or THz regions by the means of intracavity nonlinear frequency generation. The objective of this dissertation is to investigate and extend the capabilities of high-power VECSELs by utilizing novel nonlinear conversion techniques. Optically pumped VECSELs based on GaAs semiconductor heterostructures have been demonstrated to provide exceptionally high output powers covering the 900 to 1200 nm spectral region with diffraction limited beam quality. The free space cavity design allows for access to the high intracavity circulating powers where high efficiency nonlinear frequency conversions and wavelength tuning can be obtained. As an introduction, this dissertation consists of a brief history of the development of VECSELs as well as wafer design, chip fabrication and resonator cavity design for optimal frequency conversion. Specifically, the different types of laser cavities such as: linear cavity, V-shaped cavity and patented T-shaped cavity are described, since their optimization is crucial for transverse mode quality, stability, tunability and efficient frequency conversion. All types of nonlinear conversions such as second harmonic, sum frequency and difference frequency generation are discussed in extensive detail. The theoretical simulation and the development of the high-power, tunable blue and green VECSEL by the means of type I second harmonic generation in a V- cavity is presented. Tens of watts of output power for both blue and green wavelengths prove the viability for VECSELs to replace the other types of lasers currently used for applications in laser light shows, for Ti:Sapphire pumping, and for medical applications such as laser skin resurfacing. The novel, recently patented, two-chip T-cavity configuration allowing for spatial overlap of two, separate VECSEL cavities is described in detail. This type of setup is further used to demonstrate type II sum frequency generation to green with multi-watt output, and the full potential of the T-cavity is utilized by achieving type II difference frequency generation to the mid-IR spectral region. The tunable output around 5.4 microm with over 10 mW power is showcased. In the same manner the first attempts to generate THz radiation are discussed. Finally, a slightly modified T-cavity VECSEL is used to reach the UV spectral regions thanks to type I fourth harmonic generation. Over 100 mW at around 265 nm is obtained in a setup which utilizes no stabilization techniques. The dissertation demonstrates the flexibility of the VECSEL in achieving broad spectral coverage and thus its potential for a wide range of applications.

High-field/high-pressure ESR

NASA Astrophysics Data System (ADS)

Sakurai, T.; Okubo, S.; Ohta, H.

2017-07-01

We present a historical review of high-pressure ESR systems with emphasis on our recent development of a high-pressure, high-field, multi-frequency ESR system. Until 2000, the X-band system was almost established using a resonator filled with dielectric materials or a combination of the anvil cell and dielectric resonators. Recent developments have shifted from that in the low-frequency region, such as X-band, to that in multi-frequency region. High-pressure, high-field, multi-frequency ESR systems are classified into two types. First are the systems that use a vector network analyzer or a quasi-optical bridge, which have high sensitivity but a limited frequency region; the second are like our system, which has a very broad frequency region covering the THz region, but lower sensitivity. We will demonstrate the usefulness of our high-pressure ESR system, in addition to its experimental limitations. We also discuss the recent progress of our system and future plans.

Relevance of GaAs(001) surface electronic structure for high frequency dispersion on n-type accumulation capacitance

NASA Astrophysics Data System (ADS)

Pi, T. W.; Chen, W. S.; Lin, Y. H.; Cheng, Y. T.; Wei, G. J.; Lin, K. Y.; Cheng, C.-P.; Kwo, J.; Hong, M.

2017-01-01

This study investigates the origin of long-puzzled high frequency dispersion on the accumulation region of capacitance-voltage characteristics in an n-type GaAs-based metal-oxide-semiconductor. Probed adatoms with a high Pauling electronegativity, Ag and Au, unexpectedly donate charge to the contacted As/Ga atoms of as-grown α2 GaAs(001)-2 × 4 surfaces. The GaAs surface atoms behave as charge acceptors, and if not properly passivated, they would trap those electrons accumulated at the oxide and semiconductor interface under a positive bias. The exemplified core-level spectra of the Al2O3/n-GaAs(001)-2 × 4 and the Al2O3/n-GaAs(001)-4 × 6 interfaces exhibit remnant of pristine surface As emission, thereby causing high frequency dispersion in the accumulation region. For the p-type GaAs, electrons under a negatively biased condition are expelled from the interface, thereby avoiding becoming trapped.

Carbon Dioxide and Fruit Odor Transduction in Drosophila Olfactory Neurons. What Controls their Dynamic Properties?

PubMed Central

French, Andrew S.; Meisner, Shannon; Su, Chih-Ying; Torkkeli, Päivi H.

2014-01-01

We measured frequency response functions between odorants and action potentials in two types of neurons in Drosophila antennal basiconic sensilla. CO2 was used to stimulate ab1C neurons, and the fruit odor ethyl butyrate was used to stimulate ab3A neurons. We also measured frequency response functions for light-induced action potential responses from transgenic flies expressing H134R-channelrhodopsin-2 (ChR2) in the ab1C and ab3A neurons. Frequency response functions for all stimulation methods were well-fitted by a band-pass filter function with two time constants that determined the lower and upper frequency limits of the response. Low frequency time constants were the same in each type of neuron, independent of stimulus method, but varied between neuron types. High frequency time constants were significantly slower with ethyl butyrate stimulation than light or CO2 stimulation. In spite of these quantitative differences, there were strong similarities in the form and frequency ranges of all responses. Since light-activated ChR2 depolarizes neurons directly, rather than through a chemoreceptor mechanism, these data suggest that low frequency dynamic properties of Drosophila olfactory sensilla are dominated by neuron-specific ionic processes during action potential production. In contrast, high frequency dynamics are limited by processes associated with earlier steps in odor transduction, and CO2 is detected more rapidly than fruit odor. PMID:24466044

Microstructure and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

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

Shao, S. F.; Zhang, J. L.; Zheng, P.

2006-04-15

CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) ceramics are prepared by the conventional solid-state reaction method under various sintering temperatures from 1000 to 1120 deg. C at an interval of 10 deg. C. Microstructures and crystalline structures are examined by scanning electronic microscopy and x-ray diffraction, respectively. Dielectric properties and complex impedances are investigated within the frequency range of 40 Hz-110 MHz over the temperature region from room temperature to 350 deg. C. It has been disclosed that the microstructures can be categorized into three different types: type A (with the small but uniform grain sizes), type B (with the bimodal distributionmore » of grain sizes) and type C (with the large and uniform grain sizes), respectively. The largeness of low-frequency dielectric permittivity at room temperature is closely related to the microstructure. Ceramics with different types of microstructures show the diverse temperature-dependent behaviors of electrical properties. However, the existence of some common characteristics is also found among them. For all of the ceramics, a Debye-type relaxation emerges in the frequency range of 100 Hz-100 kHz at high measuring temperatures, which has the larger dielectric dispersion strength than the one known in the frequency range above 100 kHz. Thus, the high-temperature dielectric dispersion exhibits a large low-frequency response and two Debye-type relaxations. Furthermore, all of the ceramics show three semicircles in the complex impedance plane. These semicircles are considered to represent individually different electrical mechanisms, among which the one in the low-frequency range arises most probably from the contribution of the domain boundaries, and the other two are ascribed to the contributions of the domains and the grain boundaries, respectively.« less

Echolocation signals and transmission beam pattern of a false killer whale (Pseudorca crassidens).

PubMed

Au, W W; Pawloski, J L; Nachtigall, P E; Blonz, M; Gisner, R C

1995-07-01

The echolocation transmission beam pattern of a false killer whale (Pseudorca crassidens) was measured in the vertical and horizontal planes. A vertical array of seven broadband miniature hydrophones was used to measure the beam pattern in the vertical plane and a horizontal array of the same hydrophones was used in the horizontal plane. The measurements were performed in the open waters of Kaneohe Bay, Oahu, Hawaii, while the whale performed a target discrimination task. Four types of signals, characterized by their frequency spectra, were measured. Type-1 signals had a single low-frequency peak at 40 +/- 9 kHz and a low-amplitude shoulder at high frequencies. Type-2 signals had a bimodal frequency characteristic with a primary peak at 46 +/- 7 kHz and a secondary peak at 88 +/- 13 kHz. Type-3 signals were also bimodal but with a primary peak at 100 +/- 7 kHz and a secondary peak at 49 +/- 9 kHz. Type-4 signals had a single high-frequency peak at 104 +/- 7 kHz. The center frequency of the signals were found to be linearly correlated to the peak-to-peak source level, increasing with increasing source level. The major axis of the vertical beam was directed slightly downward between 0 and -5 degrees, in contrast to the +5 to 10 degrees for Tursiops and Delphinapterus. The beam in the horizontal plane was directed forward between 0 degrees and -5 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Global Model for Asymmetric, Diode-Type Dual Frequency Capacitive Discharge

NASA Astrophysics Data System (ADS)

Kim, Jisoo; Lieberman, M. A.; Lichtenberg, A. J.

2003-10-01

Dual frequency capacitive reactors can have desirable properties for dielectric etch: low cost, robust uniformity over large areas, and control of dissociation. In the ideal case, the high frequency power controls the plasma density (ion flux) and the low frequency voltage controls the ion bombarding energy. Typical operating conditions are: discharge radius 15-30 cm, length 1-3 cm, pressure 30-200 mTorr, high frequency 27.1-160 MHz, low frequency 2-13.6 MHz, and powers of 500-3000 W for both high and low frequencies. The decoupling of the high and low frequencies is an important feature of dual frequency capacitive discharges. In this work, we describe a global (volume-averaged) model having different top and bottom plate areas that incorporates particle balance, and ohmic and stochastic heating for high and low frequencies. The model is used to obtain the decoupling of high and low frequencies and to investigate limitations to ideal decoupling. Support provided by Lam Research, NSF Grant ECS-0139956, California industries, and UC-SMART Contract SM99-10051.

High frequency components of ship noise in shallow water with a discussion of implications for harbor porpoises (Phocoena phocoena).

PubMed

Hermannsen, Line; Beedholm, Kristian; Tougaard, Jakob; Madsen, Peter T

2014-10-01

Growing ship traffic worldwide has led to increased vessel noise with possible negative impacts on marine life. Most research has focused on low frequency components of ship noise, but for high-frequency specialists, such as the harbor porpoise (Phocoena phocoena), medium-to-high frequency noise components are likely more of a concern. To test for biologically relevant levels of medium-to-high frequency vessel noise, different types of Automatic Identification System located vessels were recorded using a broadband recording system in four heavily ship-trafficked marine habitats in Denmark. Vessel noise from a range of different ship types substantially elevated ambient noise levels across the entire recording band from 0.025 to 160 kHz at ranges between 60 and 1000 m. These ship noise levels are estimated to cause hearing range reduction of >20 dB (at 1 and 10 kHz) from ships passing at distances of 1190 m and >30 dB reduction (at 125 kHz) from ships at distances of 490 m or less. It is concluded that a diverse range of vessels produce substantial noise at high frequencies, where toothed whale hearing is most sensitive, and that vessel noise should be considered over a broad frequency range, when assessing noise effects on porpoises and other small toothed whales.

Development of high frequency low weight power magnetics for aerospace power systems

NASA Technical Reports Server (NTRS)

Schwarze, G. E.

1984-01-01

A dominant design consideration in the development of space type power mangetic devices is the application of reliable thermal control methods to prevent device failure which is due to excessive temperature rises and hot temperatures in critical areas. The resultant design must also yield low weight, high efficiency, high reliability and maintainability, and long life. The weight savings and high efficiency that results by going to high frequency and unique thermal control techniques is demonstrated by the development of a 25 kVA, 20 kHz space type transformer under the power magnetics technology program. Work in the area of power rotary transformer is also discussed.

A Transforming Marker That Produces Merodiploids with High Efficiency and Stable Transformants with Low Efficiency in Streptococcus

PubMed Central

Ravin, Arnold W.; Ma, Michael

1975-01-01

A mutation (ery-r8) conferring a high level of resistance to erythromycin in the Challis strain of Streptoccus sanguis can be transferred to wild-type erythromycin-sensitive recipients via single molecules of donor DNA. The transformants thus produced are of two types: (1) cells slightly more resistant to erythromycin than wild-type and capable of segregating (at a frequency of 2 x 10-4/bacterium/generation) either wild-type or highly-resistant cells like the original donor type; (2) cells phenotypically and genotypically identical to the original donor type. The unstable diploids (ery-r8/+) occur with a frequency equivalent to that obtained with high-efficiency (HE) markers, whereas the stable donor-type (ery-r8) transformants occur with about five hundred times lower frequency. Penetration of the wild-type recipient by more than one molecule of DNA bearing the ery-r8 marker increases by as much as seven times the incidence of stable transformants. UV-irradiation of molecules bearing the ery-r8 marker diminishes their ability to cooperate in producing a stable transformant, although the UV sensitivity of stable transformant production by a single DNA molecule is not different from that of diploid production. Hence, stable transformants do not appear to be produced by a process typical of low efficiency (LE) markers, which are generally highly sensitive to ultraviolet irradiation. Moreover, stable ery-r8 transformants are produced with equally low frequencies in strains of S. pneumoniae that discriminate (hex+) and fail to discriminate (hex -) between HE and LE markers. We postulate that all transformations by the ery-r8 marker result in ery-r8/+ diploids, and that segregation results in the infrequent stable transformants of the original donor type. This hypothesis is supported by the observations that rifampin treatment of ery-r8/+ populations increases the frequency of segregation and similar treatment of wild-type recipients undergoing transformation by the ery-r8 marker increases the frequency of stable transformants.—In producing the ery-r8/+ transformant the r8 allele is integrated close to the site of its wild-type homolog, since single molecules of DNA from this transformant can be shown to carry both alleles. Segregation of either the ery-r8 or + allele is not detectably enhanced by acridine orange or thymidine deprivation.—The ery-r8 marker occurs close to a site of mutation (ery-r2) which confers erythromycin resistance upon ribosomes. When the r2 and r8 markers are jointly transferred, ery-r2-r8/+ genomes are produced in which the r2 marker is stably integrated but the r8 marker is unstably adjoined to its wild-type homolog. Thus, the duplicated region can be quite short. When the ery-r8 marker is stably integrated, the region of the marker is refractory to subsequent transformation. Markers with properties like ery-r8 are not particularly rare, being found with a frequency of about 4% among spontaneous mutations to erythromycin resistance. PMID:1232022

Identifying Early Onset of Hearing Loss in Young Adults With Diabetes Mellitus Type 2 Using High Frequency Audiometry.

PubMed

Vignesh, S S; Jaya, V; Moses, Anand; Muraleedharan, A

2015-09-01

Diabetes mellitus (DM) is a metabolic disorder caused by hyperglycemia which leads to dysfunction of various organs. Hearing acuity is equally hindered by this disorder. Among individuals with DM audiological characteristics of DM type 1 are of great concern in the literature. This study aims at establishing high frequency audiometry (HFA) as a useful tool in identifying early onset of hearing loss in individuals with DM type 2. 20 non-diabetic participants and 20 individuals with DM type 2 in the age range of 20-40 years were considered for the study. Subjects in both groups underwent otoscopic examination, PTA at 0.25, 0.5, 1, 2, 4 and 8 kHz and HFA at 9, 10, 11.2, 12.5, 14 and 16 kHz. Results revealed statistically significant difference in thresholds of both PTA and HFA at all frequencies across the group, but the mean threshold difference between the diabetic and non-diabetic group was marked in HFA than in PTA. In the diabetic subjects the thresholds of PTA was within 25 dBHL at all frequencies when compared to the thresholds of HFA. Individuals with DM type 2 showed bilateral symmetrical mild hearing loss in HFA and the hearing loss increased with ascending test frequencies from 9,000 to 16,000 Hz. Mild hearing loss in HFA is an indicator for early onset of hearing loss in DM type 2. Hence this present study emphasis the clinical utility of HFA in young adults with DM type 2.

Frequency-Stable Ionic-Type Hybrid Gate Dielectrics for High Mobility Solution-Processed Metal-Oxide Thin-Film Transistors

PubMed Central

Heo, Jae Sang; Choi, Seungbeom; Jo, Jeong-Wan; Kang, Jingu; Park, Ho-Hyun; Kim, Yong-Hoon; Park, Sung Kyu

2017-01-01

In this paper, we demonstrate high mobility solution-processed metal-oxide thin-film transistors (TFTs) by using a high-frequency-stable ionic-type hybrid gate dielectric (HGD). The HGD gate dielectric, a blend of sol-gel aluminum oxide (AlOx) and poly(4-vinylphenol) (PVP), exhibited high dielectric constant (ε~8.15) and high-frequency-stable characteristics (1 MHz). Using the ionic-type HGD as a gate dielectric layer, an minimal electron-double-layer (EDL) can be formed at the gate dielectric/InOx interface, enhancing the field-effect mobility of the TFTs. Particularly, using the ionic-type HGD gate dielectrics annealed at 350 °C, InOx TFTs having an average field-effect mobility of 16.1 cm2/Vs were achieved (maximum mobility of 24 cm2/Vs). Furthermore, the ionic-type HGD gate dielectrics can be processed at a low temperature of 150 °C, which may enable their applications in low-thermal-budget plastic and elastomeric substrates. In addition, we systematically studied the operational stability of the InOx TFTs using the HGD gate dielectric, and it was observed that the HGD gate dielectric effectively suppressed the negative threshold voltage shift during the negative-illumination-bias stress possibly owing to the recombination of hole carriers injected in the gate dielectric with the negatively charged ionic species in the HGD gate dielectric. PMID:28772972

Chip-Scale Architectures for Precise Optical Frequency Synthesis

NASA Astrophysics Data System (ADS)

Yang, Jinghui

Scientists and engineers have investigated various types of stable and accurate optical synthesizers, where mode-locked laser based optical frequency comb synthesizers have been widely investigated. These frequency combs bridge the frequencies from optical domain to microwave domain with orders of magnitude difference, providing a metrological tool for various platforms. The demand for highly robust, scalable, compact and cost-effective femtosecond-laser synthesizers, however, are of great importance for applications in air- or space-borne platforms, where low cost and rugged packaging are particularly required. This has been afforded in the past several years due to breakthroughs in chip-scale nanofabrication, bringing advances in optical frequency combs down to semiconductor chips. These platforms, with significantly enhanced light-matter interaction, provide a fertile sandbox for research rich in nonlinear dynamics, and offer a reliable route towards low-phase noise photonic oscillators, broadband optical frequency synthesizers, miniaturized optical clockwork, and coherent terabit communications. The dissertation explores various types of optical frequency comb synthesizers based on nonlinear microresonators. Firstly, the fundamental mechanism of mode-locking in a high-quality factor microresonator is examined, supported by ultrafast optical characterizations, analytical closed-form solutions and numerical modeling. In the evolution of these frequency microcombs, the key nonlinear dynamical effect governing the comb state coherence is rigorously analyzed. Secondly, a prototype of chip-scale optical frequency synthesizer is demonstrated, with the laser frequency comb stabilized down to instrument-limited 50-mHz RF frequency inaccuracies and 10-16 fractional frequency inaccuracies, near the fundamental limits. Thirdly, a globally stable Turing pattern is achieved and characterized in these nonlinear resonators with high-efficiency conversion, subsequently generating coherent high-power terahertz radiation via plasmonic photomixers. Finally, a new universal modality of frequency combs is discussed, including satellite states, dynamical tunability, and high efficiency conversion towards direct chip-scale optical frequency synthesis at the precision metrology frontiers.

In Situ Detection of Strong Langmuir Turbulence Processes in Solar Type III Radio Bursts

NASA Technical Reports Server (NTRS)

Golla, Thejappa; Macdowall, Robert J.; Bergamo, M.

2012-01-01

The high time resolution observations obtained by the WAVES experiment of the STEREO spacecraft in solar type III radio bursts show that Langmuir waves often occur as intense localized wave packets. These wave packets are characterized by short durations of only a few ms and peak intensities, which well exceed the supersonic modulational instability (MI) thresholds. These timescales and peak intensities satisfy the criterion of the solitons collapsed to spatial scales of a few hundred Debye lengths. The spectra of these wave packets consist of primary spectral peaks corresponding to beam-resonant Langmuir waves, two or more sidebands corresponding to down-shifted and up-shifted daughter Langmuir waves, and low frequency enhancements below a few hundred Hz corresponding to daughter ion sound waves. The frequencies and wave numbers of these spectral components satisfy the resonance conditions of the modulational instability (MI). Moreover, the tricoherences, computed using trispectral analysis techniques show that these spectral components are coupled to each other with a high degree of coherency as expected of the MI type of four wave interactions. The high intensities, short scale lengths, sideband spectral structures and low frequency spectral enhancements and, high levels of tricoherences amongst the spectral components of these wave packets provide unambiguous evidence for the supersonic MI and related strong turbulence processes in type III radio bursts. The implication of these observations include: (1) the MI and related strong turbulence processes often occur in type III source regions, (2) the strong turbulence processes probably play very important roles in beam stabilization as well as conversion of Langmuir waves into escaping radiation at the fundamental and second harmonic of the electron plasma frequency, fpe, and (3) the Langmuir collapse probably follows the route of MI in type III radio bursts.

Interpretation of the BRITE oscillation spectra of the early B-type stars: ν Eri and α Lupi

NASA Astrophysics Data System (ADS)

Walczak, P.; Daszyńska-Daszkiewicz, J.; Pamyatnykh, A.; Handler, G.; Pigulski, A.

2017-09-01

ν Eridani is a well known multiperiodic β Cephei pulsator which exhibits also the SPB (Slowly Pulsating B-type stars) type modes. Recent frequency analysis of the BRITE photometry of α Lupi showed that the star is also a hybrid β Cep/SPB pulsator, in which both high and low frequencies were detected. We construct complex seismic models in order to account for the observed frequency range, the values of the frequencies themselves and the non-adiabatic parameter f for the dominant mode. Our studies suggest that significant modifications of the opacity profile at the temperature range log{T}\\in (5.0-5.5) are necessary to fulfill all these requirements.

Interplay between morphology and frequency in lexical access: The case of the base frequency effect

PubMed Central

Vannest, Jennifer; Newport, Elissa L.; Newman, Aaron J.; Bavelier, Daphne

2011-01-01

A major issue in lexical processing concerns storage and access of lexical items. Here we make use of the base frequency effect to examine this. Specifically, reaction time to morphologically complex words (words made up of base and suffix, e.g., agree+able) typically reflects frequency of the base element (i.e., total frequency of all words in which agree appears) rather than surface word frequency (i.e., frequency of agreeable itself). We term these complex words decomposable. However, a class of words termed whole-word do not show such sensitivity to base frequency (e.g., serenity). Using an event-related MRI design, we exploited the fact that processing low-frequency words increases BOLD activity relative to high frequency ones, and examined effects of base frequency on brain activity for decomposable and whole-word items. Morphologically complex words, half high and half low base frequency, were compared to matched high and low frequency simple monomorphemic words using a lexical decision task. Morphologically complex words increased activation in left inferior frontal and left superior temporal cortices versus simple words. The only area to mirror the behavioral distinction between decomposable and whole-word types was the thalamus. Surprisingly, most frequency-sensitive areas failed to show base frequency effects. This variety of responses to frequency and word type across brain areas supports an integrative view of multiple variables during lexical access, rather than a dichotomy between memory-based access and on-line computation. Lexical access appears best captured as interplay of several neural processes with different sensitivities to various linguistic factors including frequency and morphological complexity. PMID:21167136

Osteochondral lesions in distal tarsal joints of Icelandic horses reveal strong associations between hyaline and calcified cartilage abnormalities.

PubMed

Ley, C J; Ekman, S; Hansson, K; Björnsdóttir, S; Boyde, A

2014-03-25

Osteochondral lesions in the joints of the distal tarsal region of young Icelandic horses provide a natural model for the early stages of osteoarthritis (OA) in low-motion joints. We describe and characterise mineralised and non-mineralised osteochondral lesions in left distal tarsal region joint specimens from twenty-two 30 ±1 month-old Icelandic horses. Combinations of confocal scanning light microscopy, backscattered electron scanning electron microscopy (including, importantly, iodine staining) and three-dimensional microcomputed tomography were used on specimens obtained with guidance from clinical imaging. Lesion-types were described and classified into groups according to morphological features. Their locations in the hyaline articular cartilage (HAC), articular calcified cartilage (ACC), subchondral bone (SCB) and the joint margin tissues were identified and their frequency in the joints recorded. Associations and correlations between lesion-types were investigated for centrodistal joints only. In centrodistal joints the lesion-types HAC chondrocyte loss, HAC fibrillation, HAC central chondrocyte clusters, ACC arrest and ACC advance had significant associations and strong correlations. These lesion-types had moderate to high frequency in centrodistal joints but low frequencies in tarsometatarsal and talocalcaneal-centroquartal joints. Joint margin lesion-types had no significant associations with other lesion-types in the centrodistal joints but high frequency in both the centrodistal and tarsometatarsal joints. The frequency of SCB lesion-types in all joints was low. Hypermineralised infill phase lesion-types were detected. Our results emphasise close associations between HAC and ACC lesions in equine centrodistal joints and the importance of ACC lesions in the development of OA in low-motion compression-loaded equine joints.

Stellar interferometers and hypertelescopes: new insights on an angular spatial frequency approach to their non-invariant imaging

NASA Astrophysics Data System (ADS)

Dettwiller, L.; Lépine, T.

2017-12-01

A general and pure wave theory of image formation for all types of stellar interferometers, including hypertelescopes, is developed in the frame of Fresnel's paraxial approximations of diffraction. For a hypertelescope, we show that the severe lack of translation invariance leads to multiple and strong spatial frequency heterodyning, which codes the very high frequencies detected by the hypertelescope into medium spatial frequencies and introduces a moiré-type ambiguity for extended objects. This explains mathematically the disappointing appearance of poor resolution observed in some image simulations for hypertelescopes.

Numerical Simulation of Flow and Heat Transfer Characteristic of 4k Regenerators at High Frequency

NASA Astrophysics Data System (ADS)

Li, Zhuopei; Jiang, Yanlong; Gan, Zhihua; Qiu, Limin

Regenerator is a key component for all regenerative cryocoolers. 4K regenerative cryocoolers can be applied to provide cooling for low temperature superconductors, space and military infrared detectors, and medical examination etc. Stirling type pulse tube cryocoolers (SPTC), one type of regenerative cryocoolers, operate at high frequencies. As a result, SPTCs have the advantage of compact structure and low weight compared with G-M type pulse tube cryocoolers operating at low frequencies. However, as the frequency increase the thermal penetration depth of helium gas in the regenerator is greatly reduced which makes the heat transfer between the gas and the regenerator worse. In order to improve the heat transfer efficiency, regenerator materials with smaller hydraulic diameters are used. Therefore the flow resistance between the gas and the regenerator material will increase leading to larger pressure drop from the hot end to the cold end of the regenerator. The cooling performance is deteriorated due to the decreased pressure ratio (maximum pressure divided by minimum pressure) at the cold end. Also, behavior of helium at 4K deviates remarkably from that of ideal gas which has a significant influence both the flow and heat transfer characteristic within a regenerator. In this paper numerical simulation on the behavior of a 4K regenerator at high frequency is carried out to provide guidance for the optimization of the flow and heat transfer performance within a regenerator. Thermodynamic analysis of effect of the non-ideal gas behavior of helium at 4K on 4K regenerator at high frequency is investigated.

Knockdown Resistance Allele Frequencies in North American Head Louse (Anoplura: Pediculidae) Populations

PubMed Central

Yoon, Kyong Sup; Previte, Domenic J.; Hodgdon, Hilliary E.; Poole, Bryan C.; Kwon, Deok Ho; El-Ghar, Gamal E. Abo; Lee, Si Hyeock; Clark, J. Marshall

2014-01-01

The study examines the extent and frequency of a knockdown-type resistance allele (kdr type) in North American populations of human head lice. Lice were collected from 32 locations in Canada and the United States. DNA was extracted from individual lice and used to determine their zygosity using the serial invasive signal amplification technique to detect the kdr-type T917I (TI) mutation, which is most responsible for nerve insensitivity that results in the kdr phenotype and permethrin resistance. Previously sampled sites were resampled to determine if the frequency of the TI mutation was changing. The TI frequency was also reevaluated using a quantitative sequencing method on pooled DNA samples from selected sites to validate this population genotyping method. Genotyping substantiated that TI occurs at high levels in North American lice (88.4%). Overall, the TI frequency in U.S. lice was 84.4% from 1999 to 2009, increased to 99.6% from 2007 to 2009, and was 97.1% in Canadian lice in 2008. Genotyping results using the serial invasive signal amplification reaction (99.54%) and quantitative sequencing (99.45%) techniques were highly correlated. Thus, the frequencies of TI in North American head louse populations were found to be uniformly high, which may be due to the high selection pressure from the intensive and widespread use of the pyrethrins- or pyrethroid-based pediculicides over many years, and is likely a main cause of increased pediculosis and failure of pyrethrins- or permethrin-based products in Canada and the United States. Alternative approaches to treatment of head lice infestations are critically needed. PMID:24724296

Improved Transient and Steady-State Performances of Series Resonant ZCS High-Frequency Inverter-Coupled Voltage Multiplier Converter with Dual Mode PFM Control Scheme

NASA Astrophysics Data System (ADS)

Chu, Enhui; Gamage, Laknath; Ishitobi, Manabu; Hiraki, Eiji; Nakaoka, Mutsuo

The A variety of switched-mode high voltage DC power supplies using voltage-fed type or current-fed type high-frequency transformer resonant inverters using MOS gate bipolar power transistors; IGBTs have been recently developed so far for a medical-use X-ray high power generator. In general, the high voltage high power X-ray generator using voltage-fed high frequency inverter with a high voltage transformer link has to meet some performances such as (i) short rising period in start transient of X-ray tube voltage (ii) no overshoot transient response in tube voltage, (iii) minimized voltage ripple in periodic steady-state under extremely wide load variations and filament heater current fluctuation conditions of the X-ray tube. This paper presents two lossless inductor snubber-assisted series resonant zero current soft switching high-frequency inverter using a diode-capacitor ladder type voltage multiplier called Cockcroft-Walton circuit, which is effectively implemented for a high DC voltage X-ray power generator. This DC high voltage generator which incorporates pulse frequency modulated series resonant inverter using IGBT power module packages is based on the operation principle of zero current soft switching commutation scheme under discontinuous resonant current and continuous resonant current transition modes. This series capacitor compensated for transformer resonant power converter with a high frequency transformer linked voltage boost multiplier can efficiently work a novel selectively-changed dual mode PFM control scheme in order to improve the start transient and steady-state response characteristics and can completely achieve stable zero current soft switching commutation tube filament current dependent for wide load parameter setting values with the aid of two lossless inductor snubbers. It is proved on the basis of simulation and experimental results in which a simple and low cost control implementation based on selectively-changed dual-mode PFM for high-voltage X-ray DC-DC power converter with a voltage multiplier strategy has some specified voltage pattern tracking voltage response performances under rapid rising time and no overshoot in start transient tube voltage as well as the minimized steady-state voltage ripple in tube voltage.

Improving mental task classification by adding high frequency band information.

PubMed

Zhang, Li; He, Wei; He, Chuanhong; Wang, Ping

2010-02-01

Features extracted from delta, theta, alpha, beta and gamma bands spanning low frequency range are commonly used to classify scalp-recorded electroencephalogram (EEG) for designing brain-computer interface (BCI) and higher frequencies are often neglected as noise. In this paper, we implemented an experimental validation to demonstrate that high frequency components could provide helpful information for improving the performance of the mental task based BCI. Electromyography (EMG) and electrooculography (EOG) artifacts were removed by using blind source separation (BSS) techniques. Frequency band powers and asymmetry ratios from the high frequency band (40-100 Hz) together with those from the lower frequency bands were used to represent EEG features. Finally, Fisher discriminant analysis (FDA) combining with Mahalanobis distance were used as the classifier. In this study, four types of classifications were performed using EEG signals recorded from four subjects during five mental tasks. We obtained significantly higher classification accuracy by adding the high frequency band features compared to using the low frequency bands alone, which demonstrated that the information in high frequency components from scalp-recorded EEG is valuable for the mental task based BCI.

Electronic passivation of n- and p-type GaAs using chemical vapor deposited GaS

NASA Technical Reports Server (NTRS)

Tabib-Azar, Massood; Kang, Soon; Macinnes, Andrew N.; Power, Michael B.; Barron, Andrew R.; Jenkins, Phillip P.; Hepp, Aloysius F.

1993-01-01

We report on the electronic passivation of n- and p-type GaAs using CVD cubic GaS. Au/GaS/GaAs-fabricated metal-insulator-semiconductor (MIS) structures exhibit classical high-frequency capacitor vs voltage (C-V) behavior with well-defined accumulation and inversion regions. Using high- and low-frequency C-V, the interface trap densities of about 10 exp 11/eV per sq cm on both n- and p-type GaAs are determined. The electronic condition of GaS/GaAs interface did not show any deterioration after a six week time period.

Magnetic and High-Frequency Dielectric Parameters of Divalent Ion-Substituted W-Type Hexagonal Ferrites

NASA Astrophysics Data System (ADS)

Ali, Akbar; Grössinger, R.; Imran, Muhammad; Khan, M. Ajmal; Elahi, Asmat; Akhtar, Majid Niaz; Mustafa, Ghulam; Khan, Muhammad Azhar; Ullah, Hafeez; Murtaza, Ghulam; Ahmad, Mukhtar

2017-02-01

Polycrystalline W-type hexagonal ferrites with chemical formulae Ba0.5Sr0.5 Co2- x Me x Fe16O27 ( x = 0, 0.5, Me = Mn, Mg, Zn, Ni) have been prepared using sol-gel autocombustion. It has been reported in our earlier published work that all the samples exhibit a single-phase W-type hexagonal structure which was confirmed by x-ray diffraction (XRD) analysis. The values of bulk density lie in the range of 4.64-4.78 g/cm3 for all the samples which are quite high as compared to those for other types of hexaferrites. It was also observed that Zn-substituted ferrite reflects the highest (14.7 × 107 Ω-cm) whereas Mn-substituted ferrite has the lowest (11.3 × 107 Ω-cm) values of direct current (DC) electrical resistivity. The observed values of saturation magnetization ( M s) are found to be in the range of 62.01-68.7 emu/g depending upon the type of cation substitution into the hexagonal lattice. All the samples exhibit a typical soft magnetic character with low values of coercivity ( H c) that are in the range of 26-85 Oe. These ferrites may be promising materials for microwave absorbers due to their higher saturation magnetization and low coercivities. Both the dielectric constant and tangent loss decrease with increasing frequency in the lower frequency region and become constant in the higher frequency region. The much lower dielectric constant obtained in this study makes the investigated ferrites very useful for high-frequency applications, i.e. dielectric resonators and for camouflaging military targets such as ships, tanks and aircrafts, etc.

A variable passive low-frequency absorber

NASA Astrophysics Data System (ADS)

Larsen, Niels Werner; Thompson, Eric R.; Gade, Anders Christian

2005-04-01

Multi-purpose concert halls face a dilemma. They can host classical music concerts, rock concerts and spoken word performances in a matter of a short period. These different performance types require significantly different acoustic conditions in order to provide the best sound quality to both the performers and the audience. A recommended reverberation time for classical music may be in the range of 1.5-2 s for empty halls, where rock music sounds best with a reverberation time around 0.8-1 s. Modern rhythmic music often contains high levels of sound energy in the low frequency bands but still requires a high definition for good sound quality. Ideally, the absorption of the hall should be adjustable in all frequency bands in order to provide good sound quality for all types of performances. The mid and high frequency absorption is easily regulated, but adjusting the low-frequency absorption has typically been too expensive or requires too much space to be practical for multi-purpose halls. Measurements were made on a variable low-frequency absorber to develop a practical solution to the dilemma. The paper will present the results of the measurements as well as a possible design.

Definition of a temporal distribution index for high temporal resolution precipitation data over Peninsular Spain and the Balearic Islands: the fractal dimension; and its synoptic implications

NASA Astrophysics Data System (ADS)

Meseguer-Ruiz, Oliver; Osborn, Timothy J.; Sarricolea, Pablo; Jones, Philip D.; Cantos, Jorge Olcina; Serrano-Notivoli, Roberto; Martin-Vide, Javier

2018-03-01

Precipitation on the Spanish mainland and in the Balearic archipelago exhibits a high degree of spatial and temporal variability, regardless of the temporal resolution of the data considered. The fractal dimension indicates the property of self-similarity, and in the case of this study, wherein it is applied to the temporal behaviour of rainfall at a fine (10-min) resolution from a total of 48 observatories, it provides insights into its more or less convective nature. The methodology of Jenkinson & Collison which automatically classifies synoptic situations at the surface, as well as an adaptation of this methodology at 500 hPa, was applied in order to gain insights into the synoptic implications of extreme values of the fractal dimension. The highest fractal dimension values in the study area were observed in places with precipitation that has a more random behaviour over time with generally high totals. Four different regions in which the atmospheric mechanisms giving rise to precipitation at the surface differ from the corresponding above-ground mechanisms have been identified in the study area based on the fractal dimension. In the north of the Iberian Peninsula, high fractal dimension values are linked to a lower frequency of anticyclonic situations, whereas the opposite occurs in the central region. In the Mediterranean, higher fractal dimension values are associated with a higher frequency of the anticyclonic type and a lower frequency of the advective type from the east. In the south, lower fractal dimension values indicate higher frequency with respect to the anticyclonic type from the east and lower frequency with respect to the cyclonic type.

Temperature dependence of frequency response characteristics in organic field-effect transistors

NASA Astrophysics Data System (ADS)

Lu, Xubing; Minari, Takeo; Liu, Chuan; Kumatani, Akichika; Liu, J.-M.; Tsukagoshi, Kazuhito

2012-04-01

The frequency response characteristics of semiconductor devices play an essential role in the high-speed operation of electronic devices. We investigated the temperature dependence of dynamic characteristics in pentacene-based organic field-effect transistors and metal-insulator-semiconductor capacitors. As the temperature decreased, the capacitance-voltage characteristics showed large frequency dispersion and a negative shift in the flat-band voltage at high frequencies. The cutoff frequency shows Arrhenius-type temperature dependence with different activation energy values for various gate voltages. These phenomena demonstrate the effects of charge trapping on the frequency response characteristics, since decreased mobility prevents a fast charge response for alternating current signals at low temperatures.

Abnormal excitability and episodic low-frequency oscillations in the cerebral cortex of the tottering mouse.

PubMed

Cramer, Samuel W; Popa, Laurentiu S; Carter, Russell E; Chen, Gang; Ebner, Timothy J

2015-04-08

The Ca(2+) channelopathies caused by mutations of the CACNA1A gene that encodes the pore-forming subunit of the human Cav2.1 (P/Q-type) voltage-gated Ca(2+) channel include episodic ataxia type 2 (EA2). Although, in EA2 the emphasis has been on cerebellar dysfunction, patients also exhibit episodic, nonmotoric abnormalities involving the cerebral cortex. This study demonstrates episodic, low-frequency oscillations (LFOs) throughout the cerebral cortex of tottering (tg/tg) mice, a widely used model of EA2. Ranging between 0.035 and 0.11 Hz, the LFOs in tg/tg mice can spontaneously develop very high power, referred to as a high-power state. The LFOs in tg/tg mice are mediated in part by neuronal activity as tetrodotoxin decreases the oscillations and cortical neuron discharge contain the same low frequencies. The high-power state involves compensatory mechanisms because acutely decreasing P/Q-type Ca(2+) channel function in either wild-type (WT) or tg/tg mice does not induce the high-power state. In contrast, blocking l-type Ca(2+) channels, known to be upregulated in tg/tg mice, reduces the high-power state. Intriguingly, basal excitatory glutamatergic neurotransmission constrains the high-power state because blocking ionotropic or metabotropic glutamate receptors results in high-power LFOs in tg/tg but not WT mice. The high-power LFOs are decreased markedly by acetazolamide and 4-aminopyridine, the primary treatments for EA2, suggesting disease relevance. Together, these results demonstrate that the high-power LFOs in the tg/tg cerebral cortex represent a highly abnormal excitability state that may underlie noncerebellar symptoms that characterize CACNA1A mutations. Copyright © 2015 the authors 0270-6474/15/355664-16$15.00/0.

Lower Frequency of HLA-DRB1 Type 1 Diabetes Risk Alleles in Pediatric Patients with MODY.

PubMed

Urrutia, Inés; Martínez, Rosa; López-Euba, Tamara; Velayos, Teresa; Martínez de LaPiscina, Idoia; Bilbao, José Ramón; Rica, Itxaso; Castaño, Luis

2017-01-01

The aim of this study was to determine the frequency of susceptible HLA-DRB1 alleles for type 1 diabetes in a cohort of pediatric patients with a confirmed genetic diagnosis of MODY. 160 families with a proband diagnosed with type 1 diabetes and 74 families with a molecular diagnosis of MODY (61 GCK-MODY and 13 HNF1A-MODY) were categorized at high definition for HLA-DRB1 locus. According to the presence or absence of the susceptible HLA-DRB1 alleles for type 1 diabetes, we considered three different HLA-DRB1 genotypes: 0 risk alleles (no DR3 no DR4); 1 risk allele (DR3 or DR4); 2 risk alleles (DR3 and/or DR4). Compared with type 1 diabetes, patients with MODY carried higher frequency of 0 risk alleles, OR 22.7 (95% CI: 10.7-48.6) and lower frequency of 1 or 2 risk alleles, OR 0.53 (95% CI: 0.29-0.96) and OR 0.06 (95% CI: 0.02-0.18), respectively. The frequency of HLA-DRB1 risk alleles for type 1 diabetes is significantly lower in patients with MODY. In children and adolescents with diabetes, the presence of 2 risk alleles (DR3 and/or DR4) reduces the probability of MODY diagnosis, whereas the lack of risk alleles increases it. Therefore, we might consider that HLA-DRB1 provides additional information for the selection of patients with high probability of monogenic diabetes.

EVIDENCE FOR GRANULATION IN EARLY A-TYPE STARS

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

Kallinger, Thomas; Matthews, Jaymie M.

2010-03-01

Stars with spectral types earlier than about F0 on (or close) to the main sequence have long been believed to lack observable surface convection, although evolutionary models of A-type stars do predict very thin surface convective zones. We present evidence for granulation in two {delta} Scuti stars of spectral type A2: HD 174936 and HD 50844. Recent analyses of space-based CoRoT data revealed up to some 1000 frequencies in the photometry of these stars. The frequencies were interpreted as individual pulsation modes. If true, there must be large numbers of nonradial modes of very high degree l which should suffermore » cancellation effects in disk-integrated photometry (even of high space-based precision). The p-mode interpretation of all the frequencies in HD 174936 and HD 50844 depends on the assumption of white (frequency-independent) noise. Our independent analyses of the data provide an alternative explanation: most of the peaks in the Fourier spectra are the signature of non-white granulation background noise, and less than about 100 of the frequencies are actual stellar p-modes in each star. We find granulation timescales which are consistent with scaling relations that describe cooler stars with known surface convection. If the granulation interpretation is correct, the hundreds of low-amplitude Fourier peaks reported in recent studies are falsely interpreted as independent pulsation modes and a significantly lower number of frequencies are associated with pulsation, consistent with only modes of low degree.« less

Characteristics of different frequency ranges in scanning electron microscope images

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

Sim, K. S., E-mail: kssim@mmu.edu.my; Nia, M. E.; Tan, T. L.

2015-07-22

We demonstrate a new approach to characterize the frequency range in general scanning electron microscope (SEM) images. First, pure frequency images are generated from low frequency to high frequency, and then, the magnification of each type of frequency image is implemented. By comparing the edge percentage of the SEM image to the self-generated frequency images, we can define the frequency ranges of the SEM images. Characterization of frequency ranges of SEM images benefits further processing and analysis of those SEM images, such as in noise filtering and contrast enhancement.

METHOD FOR STABILIZING KLYSTRONS

DOEpatents

Magnuson, D.W.; Smith, D.F.

1959-04-14

High-frequency oscillators for the generation of microwaves, particularly a system for stabilizing frequency-modulated klystron oscillators of the reflex type, are described. The system takos advantage of the fact that a change in oscillator frequency will alter the normal phase displacement between the cavity and its modulator, creating an error voltage which is utilized to regulate the frequency of the oscillator and stabilize it.

Power Supply for Variable Frequency Induction Heating Using MERS Soft-Switching High Frequency Inverter

NASA Astrophysics Data System (ADS)

Isobe, Takanori; Kitahara, Tadayuki; Fukutani, Kazuhiko; Shimada, Ryuichi

Variable frequency induction heating has great potential for industrial heating applications due to the possibility of achieving heating distribution control; however, large-scale induction heating with variable frequency has not yet been introduced for practical use. This paper proposes a high frequency soft-switching inverter for induction heating that can achieve variable frequency operation. One challenge of variable frequency induction heating is increasing power electronics ratings. This paper indicates that its current source type dc-link configuration and soft-switching characteristics can make it possible to build a large-scale system with variable frequency capability. A 90-kVA 150-1000Hz variable frequency experimental power supply for steel strip induction heating was developed. Experiments confirmed the feasibility of variable frequency induction heating with proposed converter and the advantages of variable frequency operation.

Predictors of seizure occurrence in children undergoing pre-surgical monitoring.

PubMed

Harini, Chellamani; Singh, Kanwaljit; Takeoka, Masanori; Parulkar, Isha; Bergin, Ann Marie; Loddenkemper, Tobias; Kothare, Sanjeev V

2013-10-01

Long-Term-Monitoring (LTM) is a valuable tool for seizure localization/lateralization among children with refractory-epilepsy undergoing pre-surgical-monitoring. The aim of this study was to examine the factors predicting occurrence of single/multiple seizures in children undergoing pre-surgical monitoring in the LTM unit. Chart review was done on 95 consecutive admissions on 92 children (40 females) admitted to the LTM-unit for pre-surgical workup. Relationship between occurrence of multiple (≥ 3) seizures and factors such as home seizure-frequency, demographics, MRI-lesions/seizure-type and localization/AED usage/neurological-exam/epilepsy-duration was evaluated by logistic-regression and survival-analysis. Home seizure-frequency was further categorized into low (up-to 1/month), medium (up-to 1/week) and high (>1/week) and relationship of these categories to the occurrence of multiple seizures was evaluated. Mean length of stay was 5.24 days in all 3 groups. Home seizure frequency was the only factor predicting the occurrence of single/multiple seizures in children undergoing presurgical workup. Other factors (age/sex/MRI-lesions/seizure-type and localization/AED-usage/neurological-exam/epilepsy-duration) did not affect occurrence of single/multiple seizures or time-to-occurrence of first/second seizure. Analysis of the home-seizure frequency categories revealed that 98% admissions in high-frequency, 94% in the medium, and 77% in low-frequency group had at-least 1 seizure recorded during the monitoring. Odds of first-seizure increased in high vs. low-frequency group (p=0.01). Eighty-nine percent admissions in high-frequency, 78% in medium frequency, versus 50% in low-frequency group had ≥ 3 seizures. The odds of having ≥ 3 seizures increased in high-frequency (p=0.0005) and in medium-frequency (p=0.007), compared to low-frequency group. Mean time-to-first-seizure was 2.7 days in low-frequency, 2.1 days in medium, and 2 days in high-frequency group. Time-to-first-seizure in high and medium-frequency was less than in low-frequency group (p<0.0014 and p=0.038). Majority of the admissions (92%) admitted to the LTM-unit for pre-surgical workup had at-least one seizure during a mean length of stay of 5.24 days. Home seizure-frequency was the only predictor influencing occurrence of single/multiple seizures in the LTM unit. Patients with low seizure-frequency are at risk for completing the monitoring with less than the optimum number (<3) of seizures captured. Copyright © 2013 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Inclination dependence of QPO phase lags in black hole X-ray binaries

NASA Astrophysics Data System (ADS)

van den Eijnden, J.; Ingram, A.; Uttley, P.; Motta, S. E.; Belloni, T. M.; Gardenier, D. W.

2017-01-01

Quasi-periodic oscillations (QPOs) with frequencies from ˜0.05to30 Hz are a common feature in the X-ray emission of accreting black hole binaries. As the QPOs originate from the innermost accretion flow, they provide the opportunity to probe the behaviour of matter in extreme gravity. In this paper, we present a systematic analysis of the inclination dependence of phase lags associated with both type-B and type-C QPOs in a sample of 15 Galactic black hole binaries. We find that the phase lag at the type-C QPO frequency strongly depends on inclination, both in evolution with the QPO frequency and sign. Although we find that the type-B QPO soft lags are associated with high-inclination sources, the source sample is too small to confirm that this as a significant inclination dependence. These results are consistent with a geometrical origin of type-C QPOs and a different origin for type-B and type-C QPOs. We discuss the possibility that the phase lags originate from a pivoting spectral power law during each QPO cycle, while the inclination dependence arises from differences in dominant relativistic effects. We also search for energy dependences in the type-C QPO frequency. We confirm this effect in the three known sources (GRS 1915+105, H1743-322 and XTE J1550-564) and newly detect it in XTE J1859+226. Lastly, our results indicate that the unknown inclination sources XTE J1859+226 and MAXI J1543-564 are most consistent with a high inclination.

An integrated signal conditioner for high-frequency inductive position sensors

NASA Astrophysics Data System (ADS)

Rahal, Mohamad; Demosthenous, Andreas

2010-01-01

This paper describes the design, implementation and evaluation of a signal conditioner application-specific integrated circuit (ASIC) for high-frequency inductive non-contact position sensors. These sensors employ a radio frequency technology based on an antenna planar arrangement and a resonant target, have a high inherent resolution (0.1% of antenna length) and can measure target position over a wide distance range (<0.1 mm to >10 m). However, due to the relatively high-frequency excitation (1 MHz typically) and to the specific layouts of these sensors, there is unwanted capacitive coupling between the transmitter and receiver coils; this type of distortion reduces linearity and resolution. The ASIC, which is the first generation of its kind for this type of sensor, employs a differential mixer topology which suppresses the capacitive coupling offsets. The system architecture and circuit details are presented. The ASIC was fabricated in a 0.6 µm high-voltage CMOS technology occupying an area of 8 mm2. It dissipates about 30 mA from a 24 V power supply. The ASIC was tested with a high-frequency inductive position sensor (with an antenna length of 10.8 cm). The measured input-referred offset due to transmitter crosstalk is on average about 22 µV over a wide phase difference variation (-99° to +117°) between the transmitter and demodulating signals.

A New Type of Atom Interferometry for Testing Fundamental Physics

NASA Astrophysics Data System (ADS)

Lorek, Dennis; Lämmerzahl, Claus; Wicht, Andreas

We present a new type of atom interferometer (AI) that provides a tool for ultra-high precision tests of fundamental physics. As an example we present how an AI based on highly charged hydrogen-like atoms is affected by gravitational waves (GW). A qualitative description of the quantum interferometric measurement principle is given, the modifications in the atomic Hamiltonian caused by the GW are presented, and the size of the resulting frequency shifts in hydrogen-like atoms is estimated. For a GW amplitude of h = 10-23 the frequency shift is of the order of 110μHz for an AI based on a 91-fold charged uranium ion. A frequency difference of this size can be resolved by current AIs in 1s.

Performance Analysis of AN Engine Mount Featuring ER Fluids and Piezoactuators

NASA Astrophysics Data System (ADS)

Choi, S. H.; Choi, Y. T.; Choi, S. B.; Cheong, C. C.

Conventional rubber mounts and various types of passive or semi-active hydraulic engine mounts for a passenger vehicle have their own functional aims on the limited frequency band in the broad engine operating frequency range. In order to achieve high system performance over all frequency ranges of the engine operation, a new type of engine mount featuring electro-rheological(ER) fluids and piezoactuators is proposed in this study. A mathematical model of the proposed engine mount is derived using the bond graph method which is inherently adequate to model the interconnected hydromechanical system. In the low frequency domain, the ER fluid is activated upon imposing an electric field for vibration isolation while the piezoactuator is activated in the high frequency domain. A neuro-control algorithm is utilized to determine control electric field for the ER fluid, and H∞ control technique is adopted for the piezoactuator Comparative works between the proposed and single-actuating(ER fluid only or piezoactuator only) engine mounts are undertaken by evaluating force transmissibility over a wide operating frequency range.

DC-DC Type High-Frequency Link DC for Improved Power Quality of Cascaded Multilevel Inverter

NASA Astrophysics Data System (ADS)

Sadikin, Muhammad; Senjyu, Tomonobu; Yona, Atsushi

2013-06-01

Multilevel inverters are emerging as a new breed of power converter options for power system applications. Recent advances in power switching devices enabled the suitability of multilevel inverters for high voltage and high power applications because they are connecting several devices in series without the need of component matching. Usually, a transformerless battery energy storage system, based on a cascaded multilevel inverter, is used as a measure for voltage and frequency deviations. System can be reduced in size, weight, and cost of energy storage system. High-frequency link circuit topology is advantageous in realizing compact and light-weight power converters for uninterruptible power supply systems, new energy systems using photovoltaic-cells, fuel-cells and so on. This paper presents a DC-DC type high-frequency link DC (HFLDC) cascaded multilevel inverter. Each converter cell is implemented a control strategy for two H-bridge inverters that are controlled with the same multicarrier pulse width modulation (PWM) technique. The proposed cascaded multilevel inverter generates lower voltage total harmonic distortion (THD) in comparison with conventional cascaded multilevel inverter. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of the proposed cascaded multilevel inverter.

Pharmacological characterization of ionic currents that regulate high-frequency spontaneous activity of electromotor neurons in the weakly electric fish, Apteronotus leptorhynchus.

PubMed

Smith, G Troy

2006-01-01

The neural circuit that controls the electric organ discharge (EOD) of the brown ghost knifefish (Apteronotus leptorhynchus) contains two spontaneous oscillators. Both pacemaker neurons in the medulla and electromotor neurons (EMNs) in the spinal cord fire spontaneously at frequencies of 500-1,000 Hz to control the EOD. These neurons continue to fire in vitro at frequencies that are highly correlated with in vivo EOD frequency. Previous studies used channel blocking drugs to pharmacologically characterize ionic currents that control high-frequency firing in pacemaker neurons. The goal of the present study was to use similar techniques to investigate ionic currents in EMNs, the other type of spontaneously active neuron in the electromotor circuit. As in pacemaker neurons, high-frequency firing of EMNs was regulated primarily by tetrodotoxin-sensitive sodium currents and by potassium currents that were sensitive to 4-aminopyridine and kappaA-conotoxin SIVA, but resistant to tetraethylammonium. EMNs, however, differed from pacemaker neurons in their sensitivity to some channel blocking drugs. Alpha-dendrotoxin, which blocks a subset of Kv1 potassium channels, increased firing rates in EMNs, but not pacemaker neurons; and the sodium channel blocker muO-conotoxin MrVIA, which reduced firing rates of pacemaker neurons, had no effect on EMNs. These results suggest that similar, but not identical, ionic currents regulate high-frequency firing in EMNs and pacemaker neurons. The differences in the ionic currents expressed in pacemaker neurons and EMNs might be related to differences in the morphology, connectivity, or function of these two cell types.

Investigation of Chinese text entry performance for mobile display interfaces.

PubMed

Lin, Po-Hung

2015-01-01

This study examined the effects of panel type, frequency of use and arrangement of phonetic symbols on operation time, usability, visual fatigue and workload in text entry performance. Three types of panel (solid, touch and mixed), three types of frequency of use (low, medium and high) and two types of the arrangement of phonetic symbols (vertical and horizontal) were investigated through 30 college students in the experiment. The results indicated that panel type, frequency of use, arrangement of phonetic symbols and the interaction between panel type and frequency of use were significant factors on operation time. Panel type was also a significant factor on usability, and a touch panel and a solid panel showed better usability than a mixed panel. Furthermore, a touch panel showed good usability and the lowest workload and therefore it is recommended to use a touch panel with vertical phonetic arrangement in sending Chinese text messages. Practitioner Summary: This study found, from ergonomics considerations, that a touch panel showed good usability and it is recommended to use a touch panel with vertical phonetic arrangement in sending Chinese text messages. Mobile display manufacturers can use the results of this study as a reference for future keyboard design.

The dielectric properties of soil-water mixtures at microwave frequencies

NASA Technical Reports Server (NTRS)

Wang, J. R.

1979-01-01

Recent measurements on the dielectric constants of soil-water mixtures show the existence of two frequency regions in which the dielectric behavior of these mixtures was quite different. At the frequencies of 1.4 GHz to 5 GHz, there were strong evidences that the variations of the dielectric (epsilon) with water content (W) depended on soil type. While the real part of epsilon for sandy soils rose rapidly with the increase in W, epsilon for the high-clay content soils rose only slowly with W. As a consequence, epsilon was generally higher for the sandy soils than for the high-clay content soils at a given W. On the other hand, most of the measurements at frequencies 1 GHz indicated the increase of epsilon with W independent of soil types. At a given W, epsilon' (sandy soil) approximately equals epsilon (high-clay content soil) within the precision of the measurements. These observational features can be satisfactorily interpreted in terms of a simple dielectric relaxation model, with an appropriate choice of the mean relaxation frequency f(m) and the range of the activation energy (beta). It was found that smaller f(m) and larger beta were required for the high-clay content soils than the sandy soils in order to be consistent with the measured data.

A lightweight low-frequency sound insulation membrane-type acoustic metamaterial

NASA Astrophysics Data System (ADS)

Lu, Kuan; Wu, Jiu Hui; Guan, Dong; Gao, Nansha; Jing, Li

2016-02-01

A novel membrane-type acoustic metamaterial with a high sound transmission loss (STL) at low frequencies (⩽500Hz) was designed and the mechanisms were investigated by using negative mass density theory. This metamaterial's structure is like a sandwich with a thin (thickness=0.25mm) lightweight flexible rubber material within two layers of honeycomb cell plates. Negative mass density was demonstrated at frequencies below the first natural frequency, which results in the excellent low-frequency sound insulation. The effects of different structural parameters of the membrane on the sound-proofed performance at low frequencies were investigated by using finite element method (FEM). The numerical results show that, the STL can be modulated to higher value by changing the structural parameters, such as the membrane surface density, the unite cell film shape, and the membrane tension. The acoustic metamaterial proposed in this study could provide a potential application in the low-frequency noise insulation.

Dielectric relaxation, resonance and scaling behaviors in Sr3Co2Fe24O41 hexaferrite

PubMed Central

Tang, Rujun; Jiang, Chen; Qian, Wenhu; Jian, Jie; Zhang, Xin; Wang, Haiyan; Yang, Hao

2015-01-01

The dielectric properties of Z-type hexaferrite Sr3Co2Fe24O41 (SCFO) have been investigated as a function of temperature from 153 to 503 K between 1 and 2 GHz. The dielectric responses of SCFO are found to be frequency dependent and thermally activated. The relaxation-type dielectric behavior is observed to be dominating in the low frequency region and resonance-type dielectric behavior is found to be dominating above 108 Hz. This frequency dependence of dielectric behavior is explained by the damped harmonic oscillator model with temperature dependent coefficients. The imaginary part of impedance (Z″) and modulus (M″) spectra show that there is a distribution of relaxation times. The scaling behaviors of Z″ and M″ spectra further suggest that the distribution of relaxation times is temperature independent at low frequencies. The dielectric loss spectra at different temperatures have not shown a scaling behavior above 108 Hz. A comparison between the Z″ and the M″ spectra indicates that the short-range charges motion dominates at low temperatures and the long-range charges motion dominates at high temperatures. The above results indicate that the dielectric dispersion mechanism in SCFO is temperature independent at low frequencies and temperature dependent at high frequencies due to the domination of resonance behavior. PMID:26314913

A Hierarchical Relationship Between the Fluence Spectra and CME Kinematics in Large Solar Energetic Particle Events: A Radio Perspective

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Makela, P.; Yashiro, S.; Thakur, N.; Akiyama, S.; Xie, H.

2017-01-01

We report on further evidence that solar energetic particles are organized by the kinematic properties of coronal mass ejections (CMEs). In particular, we focus on the starting frequency of type II bursts, which is related to the distance from the Sun where the radio emission starts. We find that the three groups of solar energetic particle (SEP) events known to have distinct values of CME initial acceleration, also have distinct average starting frequencies of the associated type II bursts. SEP events with ground level enhancement (GLE) have the highest starting frequency (107 MHz), while those associated with filament eruption (FE) in quiescent regions have the lowest starting frequency (22 MHz); regular SEP events have intermediate starting frequency (81 MHz). Taking the onset time of type II bursts as the time of shock formation, we determine the shock formation heights measured from the Sun center. We find that the shocks form on average closest to the Sun (1.51 Rs) in GLE events, farthest from the Sun in FE SEP events (5.38 Rs), and at intermediate distances in regular SEP events (1.72 Rs). Finally, we present the results of a case study of a CME with high initial acceleration (approx. 3 km s-2) and a type II radio burst with high starting frequency (200 MHz) but associated with a minor SEP event. We find that the relation between the fluence spectral index and CME initial acceleration continues to hold even for this minor SEP event.

A Hierarchical Relationship Between the Fluence Spectra and CME Kinematics in Large Solar Energetic Particle Events: A Radio Perspective

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Makela, P.; Yashiro, S.; Thakur, N.; Akiyama, S.; Xie, H.

2017-01-01

We report on further evidence that solar energetic particles are organized by the kinematic properties of coronal mass ejections (CMEs). In particular, we focus on the starting frequency of type II bursts, which is related to the distance from the Sun where the radio emission starts. We find that the three groups of solar energetic particle (SEP) events known to have distinct values of CME initial acceleration, also have distinct average starting frequencies of the associated type II bursts. SEP events with ground level enhancement (GLE) have the highest starting frequency (107 MHz), while those associated with filament eruption (FE) in quiescent regions have the lowest starting frequency (22 MHz); regular SEP events have intermediate starting frequency (81 MHz). Taking the onset time of type II bursts as the time of shock formation, we determine the shock formation heights measured from the Sun center. We find that the shocks form on average closest to the Sun (1.51 Rs) in GLE events, farthest from the Sun in FE SEP events (5.38 Rs), and at intermediate distances in regular SEP events (1.72 Rs). Finally, we present the results of a case study of a CME with high initial acceleration (approx.3 km s-2) and a type II radio burst with high starting frequency (approx. 200 MHz) but associated with a minor SEP event. We find that the relation between the fluence spectral index and CME initial acceleration continues to hold even for this minor SEP event.

Characterization of Acoustic Streaming Beyond 100 MHz

NASA Astrophysics Data System (ADS)

Eisener, J.; Lippert, A.; Nowak, T.; Cairós, C.; Reuter, F.; Mettin, R.

The aim of this study is to investigate acoustic streaming in water at very high ultrasonic frequencies, namely beyond 100 MHz. At such high frequencies, the dissipation length of acoustic waves shrinks considerably, and the acoustic streaming transforms from the well-known Eckart type into a Stuart-Lighthill type: While Eckart streaming is driven by a small momentum transfer along the path of a weakly damped travelling sound wave, Stuart-Lighthill streaming is generated by rather local and strong momentum transfer of a highly damped and therefore rapidly decaying wave. Then the inertia of the induced flow cannot be neglected anymore, and a potentially turbulent jet flow emerges. Here we report on streaming velocity measurements for the case where the sound is completely absorbed within a region much smaller than the generated jet. In contrast to previous work in this frequency range, where mainly surface acoustic wave transducers have been employed, we use piston-type transducers that emit vertically to the transducer surface. The acoustic streaming effects are characterized by ink front tracking and particle tracking velocimetry, and by numerical studies. The results show narrow high-speed jet flows that extend much farther into the liquid than the acoustic field. Velocities of several m/s are observed.

Lamb dip CRDS of highly saturated transitions of water near 1.4 μm

NASA Astrophysics Data System (ADS)

Kassi, S.; Stoltmann, T.; Casado, M.; Daëron, M.; Campargue, A.

2018-02-01

Doppler-free saturated-absorption Lamb dips were measured at sub-Pa pressures on rovibrational lines of H216O near 7180 cm-1, using optical feedback frequency stabilized cavity ring-down spectroscopy. The saturation of the considered lines is so high that at the early stage of the ring down, the cavity loss rate remains unaffected by the absorption. By referencing the laser source to an optical frequency comb, transition frequencies are determined down to 100 Hz precision and kHz accuracy. The developed setup allows resolving highly K-type blended doublets separated by about 10 MHz (to be compared to a HWHM Doppler width on the order of 300 MHz). A comparison with the most recent spectroscopic databases is discussed. The determined K-type splittings are found to be very well predicted by the most recent variational calculations.

Room-temperature multiferroic and magnetocapacitance effects in M-type hexaferrite BaFe10.2Sc1.8O19

NASA Astrophysics Data System (ADS)

Tang, Rujun; Zhou, Hao; You, Wenlong; Yang, Hao

2016-08-01

The room-temperature multiferroic and magnetocapacitance (MC) effects of polycrystalline M-type hexaferrite BaFe10.2Sc1.8O19 have been investigated. The results show that the magnetic moments of insulating BaFe10.2Sc1.8O19 can be manipulated by the electric field at room temperature, indicating the existence of magnetoelectric coupling. Moreover, large MC effects are also observed around the room temperature. A frequency dependence analysis shows that the Maxwell-Wagner type magnetoresistance effect is the dominant mechanism for MC effects at low frequencies. Both the magnetoelectric-type and non-magnetoelectric-type spin-phonon couplings contribute to the MC effects at high frequencies with the former being the dominant mechanism. The above results show that the hexaferrite BaFe10.2Sc1.8O19 is a room-temperature multiferroic material that can be potentially used in magnetoelectric devices.

Direct observations of low-energy solar electrons associated with a type 3 solar radio burst

NASA Technical Reports Server (NTRS)

Frank, L. A.; Gurnett, D. A.

1972-01-01

On 6 April 1971 a solar X-ray flare and a type 3 solar radio noise burst were observed with instrumentation on the eccentric-orbiting satellite IMP 6. The type 3 solar radio noise burst was detected down to a frequency of 31 kHz. A highly anisotropic packet of low-energy solar electron intensities arrived at the satellite approximately 6000 seconds after the onset of the solar flare. This packet of solar electron intensities was observed for 4200 seconds. Maximum differential intensities of the solar electrons were in the energy range of one to several keV. The frequency drift rate of the type 3 radio noise at frequencies below 178 kHz also indicated an average particle speed corresponding to that of a 3-keV electron. The simultaneous observations of these solar electron intensities and of the type 3 solar radio burst are presented, and their interrelationships are explored.

Environment Dependence of Disk Morphology of Spiral Galaxies

NASA Astrophysics Data System (ADS)

Ann, Hong Bae

2014-02-01

We analyze the dependence of disk morphology (arm class, Hubble type, bar type) of nearby spiral galaxies on the galaxy environment by using local background density (Σ_{n}), project distance (r_{p}), and tidal index (TI) as measures of the environment. There is a strong dependence of arm class and Hubble type on the galaxy environment, while the bar type exhibits a weak dependence with a high frequency of SB galaxies in high density regions. Grand design fractions and early-type fractions increase with increasing Σ_{n}, 1/r_{p}, and TI, while fractions of flocculent spirals and late-type spirals decrease. Multiple-arm and intermediate-type spirals exhibit nearly constant fractions with weak trends similar to grand design and early-type spirals. While bar types show only a marginal dependence on Σ_{n}, they show a fairly clear dependence on r_{p} with a high frequency of SB galaxies at small r_{p}. The arm class also exhibits a stronger correlation with r_{p} than Σ_{n} and TI, whereas the Hubble type exhibits similar correlations with Σ_{n} and r_{p}. This suggests that the arm class is mostly affected by the nearest neighbor while the Hubble type is affected by the local densities contributed by neighboring galaxies as well as the nearest neighbor.

On the Directivity of Low-Frequency Type IV Radio Bursts

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Akiyama, S.; Makela, P.; Yashiro, S.; Cairns, I. H.

2016-01-01

An intense type IV radio burst was observed by the STEREO Behind (STB) spacecraft located about 144 deg. behind Earth. The burst was associated with a large solar eruption that occurred on the backside of the Sun (N05E151) close to the disk center in the STB view. The eruption was also observed by the STEREO Ahead (STA) spacecraft (located at 149 deg. ahead of Earth) as an eruption close to the west limb (N05W60) in that view. The type IV burst was complete in STB observations in that the envelope reached the lowest frequency and then receded to higher frequencies. The burst was partial viewed from STA, revealing only the edge coming down to the lowest frequency. The type IV burst was not observed at all near Earth because the source was 61 deg. behind the east limb. The eruption was associated with a low-frequency type II burst observed in all three views, although it was not very intense. Solar energetic particles were also observed at both STEREOs and at SOHO, suggesting that the shock was much extended, consistent with the very high speed of the CME (2048 km/s). These observations suggest that the type IV emission is directed along a narrow cone above the flare site. We confirm this result statistically using the type IV bursts of solar cycle 23.

Test-retest reliability of pure-tone thresholds from 0.5 to 16 kHz using Sennheiser HDA 200 and Etymotic Research ER-2 earphones.

PubMed

Schmuziger, Nicolas; Probst, Rudolf; Smurzynski, Jacek

2004-04-01

The purposes of the study were: (1) To evaluate the intrasession test-retest reliability of pure-tone thresholds measured in the 0.5-16 kHz frequency range for a group of otologically healthy subjects using Sennheiser HDA 200 circumaural and Etymotic Research ER-2 insert earphones and (2) to compare the data with existing criteria of significant threshold shifts related to ototoxicity and noise-induced hearing loss. Auditory thresholds in the frequency range from 0.5 to 6 kHz and in the extended high-frequency range from 8 to 16 kHz were measured in one ear of 138 otologically healthy subjects (77 women, 61 men; mean age, 24.4 yr; range, 12-51 yr) using HDA 200 and ER-2 earphones. For each subject, measurements of thresholds were obtained twice for both transducers during the same test session. For analysis, the extended high-frequency range from 8 to 16 kHz was subdivided into 8 to 12.5 and 14 to 16 kHz ranges. Data for each frequency and frequency range were analyzed separately. There were no significant differences in repeatability for the two transducer types for all frequency ranges. The intrasession variability increased slightly, but significantly, as frequency increased with the greatest amount of variability in the 14 to 16 kHz range. Analyzing each individual frequency, variability was increased particularly at 16 kHz. At each individual frequency and for both transducer types, intrasession test-retest repeatability from 0.5 to 6 kHz and 8 to 16 kHz was within 10 dB for >99% and >94% of measurements, respectively. The results indicated a false-positive rate of <3% in reference to the criteria for cochleotoxicity for both transducer types. In reference to the Occupational Safety and Health Administration Standard Threshold Shift criteria for noise-induced hazards, the results showed a minor false-positive rate of <1% for the HDA 200. Repeatability was similar for both transducer types. Intrasession test-retest repeatability from 0.5 to 12.5 kHz at each individual frequency including the frequency range susceptible to noise-induced hearing loss was excellent for both transducers. Repeatability was slightly, but significantly poorer in the frequency range from 14 to 16 kHz compared with the frequency ranges from 0.5 to 6 or 8 to 12.5 kHz. Measurements in the extended high-frequency range from 8 to 14 kHz, but not up to 16 kHz, may be recommended for monitoring purposes.

Requirements on Needed Frequency Bandwidth Depending on Pulse Waveforms and Their Allowed Distortion

NASA Astrophysics Data System (ADS)

Sigmund, Milan; Brancik, Lubomir

2016-12-01

This paper deals with pulse signals influenced by loss of energy in high frequency band. Five types of pulses were tested and evaluated under various conditions. Achieved results can be helpful for some specific tasks in signal transmission. An example presents highest frequency of periodic pulse signals processed on printed circuit board.

Miniature piezoresistive solid state integrated pressure sensors

NASA Technical Reports Server (NTRS)

Kahng, S. K.

1980-01-01

The characteristics of silicon pressure sensors with an ultra-small diaphragm are described. The pressure sensors utilize rectangular diaphragm as small as 0.0127 x 0.0254 cm and a p-type Wheatstone bridge consisting of diffused piezoresistive elements, 0.000254 cm by 0.00254 cm. These sensors exhibit as high as 0.5 MHz natural frequency and 1 mV/V/psi pressure sensitivity. Fabrication techniques and high frequency results from shock tube testing and low frequency comparison with microphones are presented.

Characterizing Variability in the Distribution of High-Frequency Acoustic Backscattering in a Shallow Water Coastal Region

DTIC Science & Technology

2007-08-01

zooplankton scatterer types, perhaps dominated by copepods and gas- bearing siphonophores (Lawson et al., 2004). Similar analyses of multi-frequency...in this Gulf of Maine study region, gas-bearing siphonophores dominated scattering at all four BIOMAPER-II frequencies (Lavery et al., in press...with multi-frequency acoustics. 2. Away from these locations, other zooplankton dominated scattering, especially copepods and gas-bearing siphonophores

Behavioral self-concept as predictor of teen drinking behaviors.

PubMed

Dudovitz, Rebecca N; Li, Ning; Chung, Paul J

2013-01-01

Adolescence is a critical developmental period for self-concept (role identity). Cross-sectional studies link self-concept's behavioral conduct domain (whether teens perceive themselves as delinquent) with adolescent substance use. If self-concept actually drives substance use, then it may be an important target for intervention. In this study, we used longitudinal data from 1 school year to examine whether behavioral self-concept predicts teen drinking behaviors or vice versa. A total of 291 students from a large, predominantly Latino public high school completed a confidential computerized survey in the fall and spring of their 9th grade year. Survey measures included the frequency of alcohol use, binge drinking and at-school alcohol use in the previous 30 days; and the Harter Self-Perception Profile for Adolescents behavioral conduct subscale. Multiple regressions were performed to test whether fall self-concept predicted the frequency and type of spring drinking behavior, and whether the frequency and type of fall drinking predicted spring self-concept. Fall behavioral self-concept predicted both the frequency and type of spring drinking. Students with low versus high fall self-concept had a predicted probability of 31% versus 20% for any drinking, 20% versus 8% for binge drinking and 14% versus 4% for at-school drinking in the spring. However, neither the frequency nor the type of fall drinking significantly predicted spring self-concept. Low behavioral self-concept may precede or perhaps even drive adolescent drinking. If these results are confirmed, then prevention efforts might be enhanced by targeting high-risk teens for interventions that help develop a healthy behavioral self-concept. Copyright © 2013 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Flexible GaN for High Performance, Strainable Radio Frequency Devices (Postprint)

DTIC Science & Technology

2017-11-02

devices on van der Waals (vdW) layers has been facilitated by the recent avail - ability of high -quality atomically smooth BN and graphene epi- taxial...AFRL-RX-WP-JA-2017-0333 FLEXIBLE GaN FOR HIGH PERFORMANCE, STRAINABLE RADIO FREQUENCY DEVICES (POSTPRINT) Elizabeth A. Moore and Timothy...2. REPORT TYPE 3. DATES COVERED (From - To) 5 April 2017 Interim 8 September 2014 – 5 March 2017 4. TITLE AND SUBTITLE FLEXIBLE GaN FOR HIGH

Single InAs/GaSb nanowire low-power CMOS inverter.

PubMed

Dey, Anil W; Svensson, Johannes; Borg, B Mattias; Ek, Martin; Wernersson, Lars-Erik

2012-11-14

III-V semiconductors have so far predominately been employed for n-type transistors in high-frequency applications. This development is based on the advantageous transport properties and the large variety of heterostructure combinations in the family of III-V semiconductors. In contrast, reports on p-type devices with high hole mobility suitable for complementary metal-oxide-semiconductor (CMOS) circuits for low-power operation are scarce. In addition, the difficulty to integrate both n- and p-type devices on the same substrate without the use of complex buffer layers has hampered the development of III-V based digital logic. Here, inverters fabricated from single n-InAs/p-GaSb heterostructure nanowires are demonstrated in a simple processing scheme. Using undoped segments and aggressively scaled high-κ dielectric, enhancement mode operation suitable for digital logic is obtained for both types of transistors. State-of-the-art on- and off-state characteristics are obtained and the individual long-channel n- and p-type transistors exhibit minimum subthreshold swings of SS = 98 mV/dec and SS = 400 mV/dec, respectively, at V(ds) = 0.5 V. Inverter characteristics display a full signal swing and maximum gain of 10.5 with a small device-to-device variability. Complete inversion is measured at low frequencies although large parasitic capacitances deform the waveform at higher frequencies.

High-Performance Power-Semiconductor Packages

NASA Technical Reports Server (NTRS)

Renz, David; Hansen, Irving; Berman, Albert

1989-01-01

A 600-V, 50-A transistor and 1,200-V, 50-A diode in rugged, compact, lightweight packages intended for use in inverter-type power supplies having switching frequencies up to 20 kHz. Packages provide low-inductance connections, low loss, electrical isolation, and long-life hermetic seal. Low inductance achieved by making all electrical connections to each package on same plane. Also reduces high-frequency losses by reducing coupling into inherent shorted turns in packaging material around conductor axes. Stranded internal power conductors aid conduction at high frequencies, where skin effect predominates. Design of packages solves historical problem of separation of electrical interface from thermal interface of high-power semiconductor device.

Wide-field high spatial frequency domain imaging of tissue microstructure

NASA Astrophysics Data System (ADS)

Lin, Weihao; Zeng, Bixin; Cao, Zili; Zhu, Danfeng; Xu, M.

2018-02-01

Wide-field tissue imaging is usually not capable of resolving tissue microstructure. We present High Spatial Frequency Domain Imaging (HSFDI) - a noncontact imaging modality that spatially maps the tissue microscopic scattering structures over a large field of view. Based on an analytical reflectance model of sub-diffusive light from forward-peaked highly scattering media, HSFDI quantifies the spatially-resolved parameters of the light scattering phase function from the reflectance of structured light modulated at high spatial frequencies. We have demonstrated with ex vivo cancerous tissue to validate the robustness of HSFDI in significant contrast and differentiation of the microstructutral parameters between different types and disease states of tissue.

Methods for Counting High-Frequency Repeat Victimizations in the National Crime Victimization Survey. Technical Series Report. NCJ 237308

ERIC Educational Resources Information Center

Lauritsen, Janet L.; Owens, Jennifer Gatewood; Planty, Michael; Rand, Michael R.; Truman, Jennifer L.

2012-01-01

Examines the nature and extent of series victimization in the National Crime Victimization Survey (NCVS). This technical report assesses the general patterns of victims' responses to being asked, "How many times did this type of incident occur?" and provides data on how reports of high-frequency repeat victimizations have changed over…

Audiometric notch and extended high-frequency hearing threshold shift in relation to total leisure noise exposure: An exploratory analysis.

PubMed

Wei, Wenjia; Heinze, Stefanie; Gerstner, Doris G; Walser, Sandra M; Twardella, Dorothee; Reiter, Christina; Weilnhammer, Veronika; Perez-Alvarez, Carmelo; Steffens, Thomas; Herr, Caroline E W

2017-01-01

Studies investigating leisure noise effect on extended high frequency hearing are insufficient and they have inconsistent results. The aim of this study was to investigate if extended high-frequency hearing threshold shift is related to audiometric notch, and if total leisure noise exposure is associated with extended high-frequency hearing threshold shift. A questionnaire of the Ohrkan cohort study was used to collect information on demographics and leisure time activities. Conventional and extended high-frequency audiometry was performed. We did logistic regression between extended high-frequency hearing threshold shift and audiometric notch as well as between total leisure noise exposure and extended high-frequency hearing threshold shift. Potential confounders (sex, school type, and firecrackers) were included. Data from 278 participants (aged 18-23 years, 53.2% female) were analyzed. Associations between hearing threshold shift at 10, 11.2, 12.5, and 14 kHz with audiometric notch were observed with a higher prevalence of threshold shift at the four frequencies, compared to the notch. However, we found no associations between total leisure noise exposure and hearing threshold shift at any extended high frequency. This exploratory analysis suggests that while extended high-frequency hearing threshold shifts are not related to total leisure noise exposure, they are strongly associated with audiometric notch. This leads us to further explore the hypothesis that extended high-frequency threshold shift might be indicative of the appearance of audiometric notch at a later time point, which can be investigated in the future follow-ups of the Ohrkan cohort.

Field characteristics of an alvarez-type linac structure having chain-like electrode array

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

Odera, M.; Goto, A.; Hemmi, M.

1985-10-01

A chain-like electrode configuration in an Alvarez-type linac cavity was studied by models. The structure has been devised to get a moderate shunt impedance together with simplicity of operation, in ion velocity region of more than a few percent of that of light by incorporating focusing scheme by high frequency quadrupolar fields into an TM-010 accelerating field of an Alvarez linac. It has a chain-like electrode array instead of drift tubes containing quadrupole lenses for ordinary linacs. The chain-like electrode structure generates along its central axis, high frequency acceleration and focusing fields alternately, separating the acceleration and focusing functions inmore » space. The separation discriminates this structure from spatially uniform acceleration and focusing scheme of the RFQs devised by Kapchinsky and Teplyakov. It gives beam acceleration effects different from those by conventional linacs and reveals possibility of getting a high acceleration efficiency. Resonant frequency spectrum was found relatively simple by measurements on high frequency models. Separation of unwanted modes from the TM-010 acceleration mode is large; a few 10 MHz, at least. Tilt of the acceleration field is not very sensitive to pertubation in gap capacitance for the TM-010 mode.« less

Chronology of processes in high-gradient channels of medium-high mountains and their influence on the properties of alluvial fans

NASA Astrophysics Data System (ADS)

Šilhán, Karel

2014-02-01

High-gradient channels are the locations of the greatest geomorphological activity in medium-high mountains. The channels' frequency and character influence the contemporary morphology and morphometry of alluvial fans. There is currently no detailed information regarding the frequency of these processes in high-gradient channels and the evolution of alluvial fans in medium-high mountains in Central Europe. This study in the Moravskoslezské Beskydy Mts. analysed 22 alluvial fans (10 debris flow fans and 12 fluvial fans). The processes occurring on the fans were dated using dendrogeomorphological methods. A total of 748 increment cores were taken from 374 trees to reconstruct 153 geomorphological process events (60 debris flow and 93 floods). The frequency of the processes has been considerably increasing in the last four decades, which can be related to extensive tree cutting since the 1970s. Processes in high-gradient channels in the region (affecting the alluvial fans across the mountain range) are predominantly controlled by cyclonal activity during the warm periods of the year. Probable triggers of local events are heavy downpours in the summer. In addition, spring snowmelt has been identified as occasionally important. This study of the relations affecting the type and frequency of the processes and their effect on the properties of alluvial fans led to the creation of a universal framework for the medium-high flysch mountains of Central Europe. The framework particularly reflects the influence of the character of hydrometeorological extremes on the frequency and type of processes and their reflection in the properties of alluvial fans.

Explicit frequency equations of free vibration of a nonlocal Timoshenko beam with surface effects

NASA Astrophysics Data System (ADS)

Zhao, Hai-Sheng; Zhang, Yao; Lie, Seng-Tjhen

2018-02-01

Considerations of nonlocal elasticity and surface effects in micro- and nanoscale beams are both important for the accurate prediction of natural frequency. In this study, the governing equation of a nonlocal Timoshenko beam with surface effects is established by taking into account three types of boundary conditions: hinged-hinged, clamped-clamped and clamped-hinged ends. For a hinged-hinged beam, an exact and explicit natural frequency equation is obtained. However, for clamped-clamped and clamped-hinged beams, the solutions of corresponding frequency equations must be determined numerically due to their transcendental nature. Hence, the Fredholm integral equation approach coupled with a curve fitting method is employed to derive the approximate fundamental frequency equations, which can predict the frequency values with high accuracy. In short, explicit frequency equations of the Timoshenko beam for three types of boundary conditions are proposed to exhibit directly the dependence of the natural frequency on the nonlocal elasticity, surface elasticity, residual surface stress, shear deformation and rotatory inertia, avoiding the complicated numerical computation.

Analysis of type II and type III solar radio bursts

NASA Astrophysics Data System (ADS)

Wijesekera, J. V.; Jayaratne, K. P. S. C.; Adassuriya, J.

2018-04-01

Solar radio burst is an arrangement of a frequency space that variation with time. Most of radio burst can be identified in low frequency range such as below 200 MHz and depending on frequencies. Solar radio bursts were the first phenomenon identified in the field of radio astronomy field. Solar radio frequency range is from 70 MHz to 2.2 GHz. Most of the radio burst can be identified in a low frequency range such as below 200 MHz. Properties of low-frequency radio were analyzed this research. There are two types of solar radio bursts were analyzed, named as type II and type III radio bursts. Exponential decay type could be seen in type II, and a linear could be indicated in type III solar radio bursts. The results of the drift rate graphs show the values of each chosen solar radio burst. High drift rate values can be seen in type III solar flares whereas low to medium drift rate values can be seen in type II solar flares. In the second part of the research the Newkirk model electron density model was used to estimate the drift velocities of the solar radio bursts. Although the special origin of the solar radio burst is not known clearly we assumed. The chosen solar radio bursts were originated within the solar radius of 0.9 - 1.3 range from the photosphere. We used power low in the form of (x) = A × 10‑bx were that the electron density related to the height of the solar atmosphere. The calculation of the plasma velocity of each solar radio burst was done using the electron density model and drift rates. Therefore velocity of chosen type II solar radio bursts indicates low velocities. The values are 233.2499 Km s‑1, 815.9522 Km s‑1 and 369.5425 Km s‑1. Velocity of chosen type III solar radio bursts were 1443.058 Km s‑1and 1205.05Km s ‑1.

GPS Block 2R Time Standard Assembly (TSA) architecture

NASA Technical Reports Server (NTRS)

Baker, Anthony P.

1990-01-01

The underlying philosophy of the Global Positioning System (GPS) 2R Time Standard Assembly (TSA) architecture is to utilize two frequency sources, one fixed frequency reference source and one system frequency source, and to couple the system frequency source to the reference frequency source via a sample data loop. The system source is used to provide the basic clock frequency and timing for the space vehicle (SV) and it uses a voltage controlled crystal oscillator (VCXO) with high short term stability. The reference source is an atomic frequency standard (AFS) with high long term stability. The architecture can support any type of frequency standard. In the system design rubidium, cesium, and H2 masers outputting a canonical frequency were accommodated. The architecture is software intensive. All VCXO adjustments are digital and are calculated by a processor. They are applied to the VCXO via a digital to analog converter.

Pressure-induced emergence of unusually high-frequency transverse excitations in a liquid alkali metal: Evidence of two types of collective excitations contributing to the transverse dynamics at high pressures

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

Bryk, Taras; Lviv Polytechnic National University, 12 S. Bandera Street, UA-79013 Lviv; Ruocco, G.

Unlike phonons in crystals, the collective excitations in liquids cannot be treated as propagation of harmonic displacements of atoms around stable local energy minima. The viscoelasticity of liquids, reflected in transition from the adiabatic to elastic high-frequency speed of sound and in absence of the long-wavelength transverse excitations, results in dispersions of longitudinal (L) and transverse (T) collective excitations essentially different from the typical phonon ones. Practically, nothing is known about the effect of high pressure on the dispersion of collective excitations in liquids, which causes strong changes in liquid structure. Here dispersions of L and T collective excitations inmore » liquid Li in the range of pressures up to 186 GPa were studied by ab initio simulations. Two methodologies for dispersion calculations were used: direct estimation from the peak positions of the L/T current spectral functions and simulation-based calculations of wavenumber-dependent collective eigenmodes. It is found that at ambient pressure, the longitudinal and transverse dynamics are well separated, while at high pressures, the transverse current spectral functions, density of vibrational states, and dispersions of collective excitations yield evidence of two types of propagating modes that contribute strongly to transverse dynamics. Emergence of the unusually high-frequency transverse modes gives evidence of the breakdown of a regular viscoelastic theory of transverse dynamics, which is based on coupling of a single transverse propagating mode with shear relaxation. The explanation of the observed high-frequency shift above the viscoelastic value is given by the presence of another branch of collective excitations. With the pressure increasing, coupling between the two types of collective excitations is rationalized within a proposed extended viscoelastic model of transverse dynamics.« less

A search for two types of transverse excitations in liquid polyvalent metals at ambient pressure: An ab initio molecular dynamics study of collective excitations in liquid Al, Tl and Ni

NASA Astrophysics Data System (ADS)

Bryk, Taras; Demchuk, Taras; Jakse, Noël; Wax, Jean-François

2018-02-01

Recent findings of pressure-induced emergence of unusual high-frequency contribution to transverse current spectral functions in several simple liquid metals at high pressures raised a question whether similar features can be observed in liquid metals at ambient conditions. We report here analysis of ab initio molecular dynamics-derived longitudinal (L) and transverse (T) current spectral functions and corresponding dispersions of collective excitations in liquid polyvalent metals Al, Tl, Ni. We have not found evidences of the second branch of high-frequency transverse modes in liquid Al and Ni, while in the case of liquid Tl they were clearly present in transverse dynamics. The vibrational density of states for liquid Tl has a pronounced high-frequency shoulder, which is located right in the frequency range of the second high-frequency transverse branch, while for liquid Al and Ni the vibrational density of states has only a weak indication of possible high-frequency shoulder. The origin of specific behavior of transverse excitations in liquid Tl is discussed.

Listening Effort and Speech Recognition with Frequency Compression Amplification for Children and Adults with Hearing Loss.

PubMed

Brennan, Marc A; Lewis, Dawna; McCreery, Ryan; Kopun, Judy; Alexander, Joshua M

2017-10-01

Nonlinear frequency compression (NFC) can improve the audibility of high-frequency sounds by lowering them to a frequency where audibility is better; however, this lowering results in spectral distortion. Consequently, performance is a combination of the effects of increased access to high-frequency sounds and the detrimental effects of spectral distortion. Previous work has demonstrated positive benefits of NFC on speech recognition when NFC is set to improve audibility while minimizing distortion. However, the extent to which NFC impacts listening effort is not well understood, especially for children with sensorineural hearing loss (SNHL). To examine the impact of NFC on recognition and listening effort for speech in adults and children with SNHL. Within-subject, quasi-experimental study. Participants listened to amplified nonsense words that were (1) frequency-lowered using NFC, (2) low-pass filtered at 5 kHz to simulate the restricted bandwidth (RBW) of conventional hearing aid processing, or (3) low-pass filtered at 10 kHz to simulate extended bandwidth (EBW) amplification. Fourteen children (8-16 yr) and 14 adults (19-65 yr) with mild-to-severe SNHL. Participants listened to speech processed by a hearing aid simulator that amplified input signals to fit a prescriptive target fitting procedure. Participants were blinded to the type of processing. Participants' responses to each nonsense word were analyzed for accuracy and verbal-response time (VRT; listening effort). A multivariate analysis of variance and linear mixed model were used to determine the effect of hearing-aid signal processing on nonsense word recognition and VRT. Both children and adults identified the nonsense words and initial consonants better with EBW and NFC than with RBW. The type of processing did not affect the identification of the vowels or final consonants. There was no effect of age on recognition of the nonsense words, initial consonants, medial vowels, or final consonants. VRT did not change significantly with the type of processing or age. Both adults and children demonstrated improved speech recognition with access to the high-frequency sounds in speech. Listening effort as measured by VRT was not affected by access to high-frequency sounds. American Academy of Audiology

Relay protection features of frequency-adjustable electric drive

NASA Astrophysics Data System (ADS)

Kuprienko, V. V.

2018-03-01

The features of relay protection of high-voltage electric motors in composition of the frequency-adjustable electric drive are considered in the article. The influence of frequency converters on the stability of the operation of various types of relay protection used on electric motors is noted. Variants of circuits for connecting relay protection devices are suggested. The need to develop special relay protection devices for a frequency-adjustable electric drive is substantiated.

Plate-type metamaterials for extremely broadband low-frequency sound insulation

NASA Astrophysics Data System (ADS)

Wang, Xiaopeng; Guo, Xinwei; Chen, Tianning; Yao, Ge

2018-01-01

A novel plate-type acoustic metamaterial with a high sound transmission loss (STL) in the low-frequency range ( ≤1000 Hz) is designed, theoretically proven and then experimentally verified. The thin plates with large modulus used in this paper mean that we do not need to apply tension to the plates, which is more applicable to practical engineering, the achievement of noise reduction is better and the installation of plates is more user-friendly than that of the membranes. The effects of different structural parameters of the plates on the sound-proofed performance at low-frequencies were also investigated by experiment and finite element method (FEM). The results showed that the STL can be modulated effectively and predictably using vibration theory by changing the structural parameters, such as the radius and thickness of the plate. Furthermore, using unit cells of different geometric sizes which are responsible for different frequency regions, the stacked panels with thickness ≤16 mm and weight ≤5 kg/m2 showed high STL below 2000 Hz. The acoustic metamaterial proposed in this study could provide a potential application in the low-frequency noise insulation.

Characterization of the MEMS Directional Sound Sensor in the High Frequency (15-20 kHz) Range

DTIC Science & Technology

2011-12-01

frequency response that is almost flat from 50 Hz to 20 kHz [9]. The sound source is a Selenium loudspeaker type DH200E attached to the internal...University Science Books, 2005. [12] W. Zhang and K. Turner, “Frequency dependent fluid damping of micro/ nano flexural resonators: Experiment, model and

Power conditioning system modelling for nuclear electric propulsion

NASA Astrophysics Data System (ADS)

Metcalf, Kenneth J.

1993-11-01

NASA LeRC is currently developing a Fortran based model of a complete nuclear electric propulsion (NEP) vehicle that would be used for piloted and cargo missions to the Moon or Mars. The proposed vehicle design will use either a Brayton or K-Rankine power conversion cycle to drive a turbine coupled with a rotary alternator. Two thruster types are also being studied, ion and magnetoplasmadynamic (MPD). In support of this NEP model, Rocketdyne developed a power management and distribution (PMAD) subroutine that provides parametric outputs for selected alternator operating voltages and frequencies, thruster types, system power levels, and electronics coldplate temperatures. The end-to-end PMAD model described is based on the direct use of the alternator voltage and frequency for transmitting power to either ion or MPD thrusters. This low frequency transmission approach was compared with dc and high frequency ac designs, and determined to have the lowest mass, highest efficiency, highest reliability and lowest development costs. While its power quality is not as good as that provided by a high frequency system, it was considered adequate for both ion and MPD engine applications. The low frequency architecture will be used as the reference in future NEP PMAD studies.

Power Conditioning System Modelling for Nuclear Electric Propulsion

NASA Technical Reports Server (NTRS)

Metcalf, Kenneth J.

1993-01-01

NASA LeRC is currently developing a Fortran based model of a complete nuclear electric propulsion (NEP) vehicle that would be used for piloted and cargo missions to the Moon or Mars. The proposed vehicle design will use either a Brayton or K-Rankine power conversion cycle to drive a turbine coupled with a rotary alternator. Two thruster types are also being studied, ion and magnetoplasmadynamic (MPD). In support of this NEP model, Rocketdyne developed a power management and distribution (PMAD) subroutine that provides parametric outputs for selected alternator operating voltages and frequencies, thruster types, system power levels, and electronics coldplate temperatures. The end-to-end PMAD model described is based on the direct use of the alternator voltage and frequency for transmitting power to either ion or MPD thrusters. This low frequency transmission approach was compared with dc and high frequency ac designs, and determined to have the lowest mass, highest efficiency, highest reliability and lowest development costs. While its power quality is not as good as that provided by a high frequency system, it was considered adequate for both ion and MPD engine applications. The low frequency architecture will be used as the reference in future NEP PMAD studies.

Effects of dosage and dosing frequency on the efficacy and safety of high-dose metformin in Japanese patients with type 2 diabetes mellitus.

PubMed

Kanto, Kousei; Ito, Hiroyuki; Noso, Shinsuke; Babaya, Naru; Hiromine, Yoshihisa; Taketomo, Yasunori; Toma, Junko; Niwano, Fumimaru; Yasutake, Sara; Kawabata, Yumiko; Ikegami, Hiroshi

2017-09-30

Differences in the efficacy and safety of antidiabetic drugs among different ethnic groups are well documented. Metformin is widely used in the treatment of type 2 diabetes in Western countries, but high doses of metformin have been approved only recently for clinical use in Japan. The aim of the present study was to investigate the effects of dosage and dosing frequency on the efficacy and safety of high-dose metformin in Japanese patients. A total of 71 Japanese patients with type 2 diabetes were prospectively studied for the effects of dosage and dosing frequency on the efficacy and safety of metformin during hospitalization. Dose effects were studied in 27 patients treated with 0, 500, 1,000, 1,500 and 2,250 mg/day of metformin. The effect of dosing frequency was compared in 56 patients with 1,500 mg/day of metformin administered either two or three times per day. Significant dose-dependent improvement in daily profiles of blood glucose was observed with metformin dosages up to 1,500 mg/day, with a trend towards further improvement observed at 2,250 mg/day. The efficacy of 1,500 mg of metformin was comparable when the drug was administered either two or three times per day. The most frequently reported side-effects were gastrointestinal symptoms, which were not affected by the dosage or dosing frequency of metformin. These results show that the efficacy of high-dose metformin is dose-dependent in Japanese patients. The efficacy and safety of metformin were similar when the drug was administered either two or three times per day. © 2017 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.

Compact, Lightweight Servo-Controllable Brakes

NASA Technical Reports Server (NTRS)

Lovchik, Christopher S.; Townsend, William; Guertin, Jeffrey; Matsuoka, Yoky

2010-01-01

Compact, lightweight servo-controllable brakes capable of high torques are being developed for incorporation into robot joints. A brake of this type is based partly on the capstan effect of tension elements. In a brake of the type under development, a controllable intermediate state of torque is reached through on/off switching at a high frequency.

Overview of Solar Radio Bursts and their Sources

NASA Astrophysics Data System (ADS)

Golla, Thejappa; MacDowall, Robert J.

2018-06-01

Properties of radio bursts emitted by the Sun at frequencies below tens of MHz are reviewed. In this frequency range, the most prominent radio emissions are those of solar type II, complex type III and solar type IV radio bursts, excited probably by the energetic electron populations accelerated in completely different environments: (1) type II bursts are due to non-relativistic electrons accelerated by the CME driven interplanetary shocks, (2) complex type III bursts are due to near-relativistic electrons accelerated either by the solar flare reconnection process or by the SEP shocks, and (3) type IV bursts are due to relativistic electrons, trapped in the post-eruption arcades behind CMEs; these relativistic electrons probably are accelerated by the continued reconnection processes occurring beneath the CME. These radio bursts, which can serve as the natural plasma probes traversing the heliosphere by providing information about various crucial space plasma parameters, are also an ideal instrument for investigating acceleration mechanisms responsible for the high energy particles. The rich collection of valuable high quality radio and high time resolution in situ wave data from the WAVES experiments of the STEREO A, STEREO B and WIND spacecraft has provided an unique opportunity to study these different radio phenomena and understand the complex physics behind their excitation. We have developed Monte Carlo simulation techniques to estimate the propagation effects on the observed characteristics of these low frequency radio bursts. We will present some of the new results and describe how one can use these radio burst observations for space weather studies. We will also describe some of the non-linear plasma processes detected in the source regions of both solar type III and type II radio bursts. The analysis and simulation techniques used in these studies will be of immense use for future space based radio observations.

Variation of Static-PPP Positioning Accuracy Using GPS-Single Frequency Observations (Aswan, Egypt)

NASA Astrophysics Data System (ADS)

Farah, Ashraf

2017-06-01

Precise Point Positioning (PPP) is a technique used for position computation with a high accuracy using only one GNSS receiver. It depends on highly accurate satellite position and clock data rather than broadcast ephemeries. PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of collected observations. PPP-(dual frequency receivers) offers comparable accuracy to differential GPS. PPP-single frequency receivers has many applications such as infrastructure, hydrography and precision agriculture. PPP using low cost GPS single-frequency receivers is an area of great interest for millions of users in developing countries such as Egypt. This research presents a study for the variability of single frequency static GPS-PPP precision based on different observation durations.

A Short Range, High Accuracy Radar Ranging System,

DTIC Science & Technology

1984-12-01

may be of any type and can perform the same functions as any other type of radar (pulsed or continuous wave (CW), coherent or noncoherent , etc.). The...use of an optical carrier frequency 4 enables laser radars to take advantage of the benefits inherent in higher frequencies: higher bandwidths allow...results that are inaccurate or incorrect. Also, directing a laser beam at an aircraft cockpit from a range of 25 feet would pose a serious safety

Novel Use of Glucagon in a Closed-Loop System for Prevention of Hypoglycemia in Type 1 Diabetes

PubMed Central

Castle, Jessica R.; Engle, Julia M.; Youssef, Joseph El; Massoud, Ryan G.; Yuen, Kevin C.J.; Kagan, Ryland; Ward, W. Kenneth

2010-01-01

OBJECTIVE To minimize hypoglycemia in subjects with type 1 diabetes by automated glucagon delivery in a closed-loop insulin delivery system. RESEARCH DESIGN AND METHODS Adult subjects with type 1 diabetes underwent one closed-loop study with insulin plus placebo and one study with insulin plus glucagon, given at times of impending hypoglycemia. Seven subjects received glucagon using high-gain parameters, and six subjects received glucagon in a more prolonged manner using low-gain parameters. Blood glucose levels were measured every 10 min and insulin and glucagon infusions were adjusted every 5 min. All subjects received a portion of their usual premeal insulin after meal announcement. RESULTS Automated glucagon plus insulin delivery, compared with placebo plus insulin, significantly reduced time spent in the hypoglycemic range (15 ± 6 vs. 40 ± 10 min/day, P = 0.04). Compared with placebo, high-gain glucagon delivery reduced the frequency of hypoglycemic events (1.0 ± 0.6 vs. 2.1 ± 0.6 events/day, P = 0.01) and the need for carbohydrate treatment (1.4 ± 0.8 vs. 4.0 ± 1.4 treatments/day, P = 0.01). Glucagon given with low-gain parameters did not significantly reduce hypoglycemic event frequency (P = NS) but did reduce frequency of carbohydrate treatment (P = 0.05). CONCLUSIONS During closed-loop treatment in subjects with type 1 diabetes, high-gain pulses of glucagon decreased the frequency of hypoglycemia. Larger and longer-term studies will be required to assess the effect of ongoing glucagon treatment on overall glycemic control. PMID:20332355

Three types of ependymal cells with intracellular calcium oscillation are characterized by distinct cilia beating properties.

PubMed

Liu, Tongyu; Jin, Xingjian; Prasad, Rahul M; Sari, Youssef; Nauli, Surya M

2014-09-01

Ependymal cells are multiciliated epithelial cells that line the ventricles in the adult brain. Abnormal function or structure of ependymal cilia has been associated with various neurological deficits. For the first time, we report three distinct ependymal cell types, I, II, and III, based on their unique ciliary beating frequency and beating angle. These ependymal cells have specific localizations within the third ventricle of the mouse brain. Furthermore, neither ependymal cell types nor their localizations are altered by aging. Our high-speed fluorescence imaging analysis reveals that these ependymal cells have an intracellular pacing calcium oscillation property. Our study further shows that alcohol can significantly repress the amplitude of calcium oscillation and the frequency of ciliary beating, resulting in an overall decrease in volume replacement by the cilia. Furthermore, the pharmacological agent cilostazol could differentially increase cilia beating frequency in type II, but not in type I or type III, ependymal cells. In summary, we provide the first evidence of three distinct types of ependymal cells with calcium oscillation properties. © 2014 Wiley Periodicals, Inc.

Detection of changes of high-frequency activity by statistical time-frequency analysis in epileptic spikes

PubMed Central

Kobayashi, Katsuhiro; Jacobs, Julia; Gotman, Jean

2013-01-01

Objective A novel type of statistical time-frequency analysis was developed to elucidate changes of high-frequency EEG activity associated with epileptic spikes. Methods The method uses the Gabor Transform and detects changes of power in comparison to background activity using t-statistics that are controlled by the false discovery rate (FDR) to correct type I error of multiple testing. The analysis was applied to EEGs recorded at 2000 Hz from three patients with mesial temporal lobe epilepsy. Results Spike-related increase of high-frequency oscillations (HFOs) was clearly shown in the FDR-controlled t-spectra: it was most dramatic in spikes recorded from the hippocampus when the hippocampus was the seizure onset zone (SOZ). Depression of fast activity was observed immediately after the spikes, especially consistently in the discharges from the hippocampal SOZ. It corresponded to the slow wave part in case of spike-and-slow-wave complexes, but it was noted even in spikes without apparent slow waves. In one patient, a gradual increase of power above 200 Hz preceded spikes. Conclusions FDR-controlled t-spectra clearly detected the spike-related changes of HFOs that were unclear in standard power spectra. Significance We developed a promising tool to study the HFOs that may be closely linked to the pathophysiology of epileptogenesis. PMID:19394892

Audiometric Notch and Extended High-Frequency Hearing Threshold Shift in Relation to Total Leisure Noise Exposure: An Exploratory Analysis

PubMed Central

Wei, Wenjia; Heinze, Stefanie; Gerstner, Doris G.; Walser, Sandra M.; Twardella, Dorothee; Reiter, Christina; Weilnhammer, Veronika; Perez-Alvarez, Carmelo; Steffens, Thomas; Herr, Caroline E.W.

2017-01-01

Background: Studies investigating leisure noise effect on extended high frequency hearing are insufficient and they have inconsistent results. The aim of this study was to investigate if extended high-frequency hearing threshold shift is related to audiometric notch, and if total leisure noise exposure is associated with extended high-frequency hearing threshold shift. Materials and Methods: A questionnaire of the Ohrkan cohort study was used to collect information on demographics and leisure time activities. Conventional and extended high-frequency audiometry was performed. We did logistic regression between extended high-frequency hearing threshold shift and audiometric notch as well as between total leisure noise exposure and extended high-frequency hearing threshold shift. Potential confounders (sex, school type, and firecrackers) were included. Results: Data from 278 participants (aged 18–23 years, 53.2% female) were analyzed. Associations between hearing threshold shift at 10, 11.2, 12.5, and 14 kHz with audiometric notch were observed with a higher prevalence of threshold shift at the four frequencies, compared to the notch. However, we found no associations between total leisure noise exposure and hearing threshold shift at any extended high frequency. Conclusion: This exploratory analysis suggests that while extended high-frequency hearing threshold shifts are not related to total leisure noise exposure, they are strongly associated with audiometric notch. This leads us to further explore the hypothesis that extended high-frequency threshold shift might be indicative of the appearance of audiometric notch at a later time point, which can be investigated in the future follow-ups of the Ohrkan cohort. PMID:29319010

The Realization and Analysis of Capacitance Self Tracing (CST) Method for Wide Band Response Measurement of Carrier Type Dynamic Strain Amplifier

NASA Astrophysics Data System (ADS)

Kubodera, Shinji; Tanzawa, Tsutomu; Morisawa, Masayuki; Kiyohiro, Noriaki

Carrier type dynamic strain amplifiers are frequently used for stress measurement with strain gages. That is because the carrier type dynamic strain amplifier can conduct high precision measurement since it is highly resistant against hum noise from the power supply frequency in principle and is free from the thermoelectomotive force even if a metal contact is used in wiring to a Wheatstone bridge for measuring. A problem of the carrier type dynamic strain amplifier is generation of Capacitive component (hereinafter referred to as the C component) in an input cable connecting from the amplifier to the input sensor (Wheatstone bridge for measuring). The C component varies with cable length, cable materials, or ambient temperature change. The aforementioned changing adversely affects the stability of the amplifier. In this paper, we realize and analyze the method that increases the stability of amplifier by detecting, eliminating and self tracking the above C component constantly. Used carrier frequency at 12kHz and 28kHz. We made amplifiers with noise resistant and wide band frequency of measurement range and verified the theory of the Capacitance Self Tracing with the above amplifiers.

Energy and lighting

NASA Astrophysics Data System (ADS)

Berman, Samuel

1985-11-01

Advances in research for new types of lighting with increased efficacies (lumens/watt) are discussed in the following areas: (1) high-frequency, solid-state ballasts, (2) isotopic enhancement of mercury isotopes, (3) magnetic augmentation, (4) electrodeless, ultra-high frequency, (5) tuned phosphors, (6) two-photon phosphors, (7) heat mirrors, and (8) advanced control circuits to take advantage of daylight and occupancy. As of 1985, improvements in efficacy have been accomplished on an economic basis to save energy for (1) high frequency ballasts (25%), (2) isotopic enhancement (5%), and (8) advanced control circuits (up to 50%). Most of these advances depend on a deeper understanding of the weakly ionized plasma as a radiating and diffusing medium.

Unveiling Extreme Anisotropy in Elastic Structured Media

NASA Astrophysics Data System (ADS)

Lefebvre, G.; Antonakakis, T.; Achaoui, Y.; Craster, R. V.; Guenneau, S.; Sebbah, P.

2017-06-01

Periodic structures can be engineered to exhibit unique properties observed at symmetry points, such as zero group velocity, Dirac cones, and saddle points; identifying these and the nature of the associated modes from a direct reading of the dispersion surfaces is not straightforward, especially in three dimensions or at high frequencies when several dispersion surfaces fold back in the Brillouin zone. A recently proposed asymptotic high-frequency homogenization theory is applied to a challenging time-domain experiment with elastic waves in a pinned metallic plate. The prediction of a narrow high-frequency spectral region where the effective medium tensor dramatically switches from positive definite to indefinite is confirmed experimentally; a small frequency shift of the pulse carrier results in two distinct types of highly anisotropic modes. The underlying effective equation mirrors this behavior with a change in form from elliptic to hyperbolic exemplifying the high degree of wave control available and the importance of a simple and effective predictive model.

Large-scale screening and characterization of enteroviruses and kobuviruses infecting pigs in Vietnam

PubMed Central

Van Dung, Nguyen; Anh, Pham Hong; Van Cuong, Nguyen; Hoa, Ngo Thi; Carrique-Mas, Juan; Hien, Vo Be; Sharp, C.; Rabaa, M.; Berto, A.; Campbell, James; Baker, Stephen; Farrar, Jeremy; Woolhouse, Mark E.; Bryant, Juliet E.; Simmonds, Peter

2016-01-01

A recent survey of pigs in Dong Thap province, Vietnam identified a high frequency of enterovirus species G (EV-G) infection (144/198; 72.7 %). Amongst these was a plethora of EV-G types (EV-G1, EV-G6 and four new types EV-G8–EV-G11). To better characterize the genetic diversity of EV-G and investigate the possible existence of further circulating types, we performed a larger-scale study on 484 pig and 45 farm-bred boar faecal samples collected in 2012 and 2014, respectively. All samples from the previous and current studies were also screened for kobuviruses. The overall EV infection frequency remained extremely high (395/484; 81.6 %), but with comparable detection rates and viral loads between healthy and diarrhoeic pigs; this contrasted with less frequent detection of EV-G in boars (4/45; 8.9 %). EV was most frequently detected in pigs ≤ 14 weeks old (∼95 %) and declined in older pigs. Infections with EV-G1 and EV-G6 were most frequent, whilst less commonly detected types included EV-G3, EV-G4 and EV-G8–EV-G11, and five new types (EV-G12–EV-G16). In contrast, kobuvirus infection frequency was significantly higher in diarrhoeic pigs (40.9 versus 27.6 %; P = 0.01). Kobuviruses also showed contrasting epizootiologies and age associations; a higher prevalence was found in boars (42 %) compared with domestic pigs (29 %), with the highest infection frequency amongst pigs >52 weeks old. Although genetically diverse, all kobuviruses identified belonged to the species Aichivirus C. In summary, this study confirms infection with EV-G was endemic in Vietnamese domestic pigs and exhibits high genetic diversity and extensive inter-type recombination. PMID:26653281

Development of multi-frequency ESR system for high-pressure measurements up to 2.5 GPa

NASA Astrophysics Data System (ADS)

Sakurai, T.; Fujimoto, K.; Matsui, R.; Kawasaki, K.; Okubo, S.; Ohta, H.; Matsubayashi, K.; Uwatoko, Y.; Tanaka, H.

2015-10-01

A new piston-cylinder pressure cell for electron spin resonance (ESR) has been developed. The pressure cell consists of a double-layer hybrid-type cylinder with internal components made of the ZrO2-based ceramics. It can generate a pressure of 2 GPa repeatedly and reaches a maximum pressure of around 2.5 GPa. A high-pressure ESR system using a cryogen-free superconducting magnet up 10 T has also been developed for this hybrid-type pressure cell. The frequency region is from 50 GHz to 400 GHz. This is the first time a pressure above 2 GPa has been achieved in multi-frequency ESR system using a piston-cylinder pressure cell. We demonstrate its potential by showing the results of the high-pressure ESR of the S = 1 system with the single ion anisotropy NiSnCl6 · 6H2O and the S = 1 / 2 quantum spin system CsCuCl3. We performed ESR measurements of these systems above 2 GPa successfully.

Comparison of cryogenic low-pass filters.

PubMed

Thalmann, M; Pernau, H-F; Strunk, C; Scheer, E; Pietsch, T

2017-11-01

Low-temperature electronic transport measurements with high energy resolution require both effective low-pass filtering of high-frequency input noise and an optimized thermalization of the electronic system of the experiment. In recent years, elaborate filter designs have been developed for cryogenic low-level measurements, driven by the growing interest in fundamental quantum-physical phenomena at energy scales corresponding to temperatures in the few millikelvin regime. However, a single filter concept is often insufficient to thermalize the electronic system to the cryogenic bath and eliminate spurious high frequency noise. Moreover, the available concepts often provide inadequate filtering to operate at temperatures below 10 mK, which are routinely available now in dilution cryogenic systems. Herein we provide a comprehensive analysis of commonly used filter types, introduce a novel compact filter type based on ferrite compounds optimized for the frequency range above 20 GHz, and develop an improved filtering scheme providing adaptable broad-band low-pass characteristic for cryogenic low-level and quantum measurement applications at temperatures down to few millikelvin.

Comparison of cryogenic low-pass filters

NASA Astrophysics Data System (ADS)

Thalmann, M.; Pernau, H.-F.; Strunk, C.; Scheer, E.; Pietsch, T.

2017-11-01

Low-temperature electronic transport measurements with high energy resolution require both effective low-pass filtering of high-frequency input noise and an optimized thermalization of the electronic system of the experiment. In recent years, elaborate filter designs have been developed for cryogenic low-level measurements, driven by the growing interest in fundamental quantum-physical phenomena at energy scales corresponding to temperatures in the few millikelvin regime. However, a single filter concept is often insufficient to thermalize the electronic system to the cryogenic bath and eliminate spurious high frequency noise. Moreover, the available concepts often provide inadequate filtering to operate at temperatures below 10 mK, which are routinely available now in dilution cryogenic systems. Herein we provide a comprehensive analysis of commonly used filter types, introduce a novel compact filter type based on ferrite compounds optimized for the frequency range above 20 GHz, and develop an improved filtering scheme providing adaptable broad-band low-pass characteristic for cryogenic low-level and quantum measurement applications at temperatures down to few millikelvin.

State of water in starch-water systems in the gelatinization temperature range as investigated using dielectric relaxation spectroscopy

NASA Astrophysics Data System (ADS)

Motwani, Tanuj

Starch-water interactions occurring during gelatinization are critical for developing a mechanistic understanding of the gelatinization process. The overall goal of this project was to investigate the state of water in starch-water systems in the gelatinization temperature range using dielectric relaxation spectroscopy. In the first part of the project, the dielectric response of native wheat starch-water slurries was measured at seven different starch concentrations between 5--60% starch (w/w) in the frequency range of 200 MHz--20 GHz at 25°C. The deconvolution of the dielectric spectra using the Debye model revealed presence of up to three relaxation processes. The relaxation time range of what were considered to be the high, intermediate and low frequency relaxations were 4--9 ps, 20--25 ps and 230--620 ps, respectively. The high frequency relaxation was observed at all starch concentrations, while the intermediate and low frequency relaxation were only observed at starch concentrations of 10% and above, and 30% and above, respectively. The high frequency relaxation was attributed to bulk water, while the intermediate and low frequency relaxations were attributed to rotationally restrained water molecules present in the starch-water system. To investigate the state of water in the gelatinization temperature range, the dielectric response, gelatinization enthalpy and water absorption by 10%, 30% or 50% starch slurries were measured after heating the slurries to different end temperatures between 40--90°C for 30 min. The high frequency relaxation time for 10% starch slurry dropped significantly (P<0.001) upon heating up to 60°C. For 30% and 50% starch slurries, high frequency relaxation times were not significantly influenced (P>0.159) by heating up to 80°C. The intermediate and low frequency relaxation times were not significantly influenced (P>0.712) by heating for all starch concentrations. Also, the amount of water associated with the three relaxations was not significantly influenced by heating (P >0.187). The water absorption results indicated that highest water uptake was achieved in the 10% starch slurry. The endothermic peak associated with gelatinization either vanished or was diminished after heating the slurries to 60°C and above, suggesting that native granular order was not necessary for the existence of the three separate states of water. In the second part of the project, the dielectric response of starch-water systems was investigated in the presence or absence of glucose or maltose. Dielectric response of 10% starch + 10% sugar, 10% starch + 20% sugar or 10% starch + 30% sugar slurries was measured in the frequency range of 200 MHz--20 GHz after heating the slurries to different end temperatures between 25--90°C for 30 min. The dielectric spectra of the slurries could be deconvoluted to obtain up to three Debye-type relaxations. The relaxation time range of high, intermediate and low frequency relaxations were 4--7 ps, 17--26 ps and 175--335 ps, respectively, at 25°C. The high frequency relaxation was the dominant relaxation in slurries containing 10% sugar, and the intermediate frequency relaxation was the dominant relaxation in slurries containing 30% sugar at 25°C. The high frequency relaxation time decreased upon heating up to 60°C but was not significantly influenced (P>0.102) by the concentration or the type of sugar. Intermediate and low frequency relaxation times were not significantly influenced (P>0.419) by heating or sugar type. The relative strengths of the intermediate frequency relaxation dropped while that of high frequency relaxation increased upon heating up to 50°C. The relative strength of low frequency relaxation (P>0.561) was not influenced by heating. The static dielectric constant decreased upon heating but was not influenced by the type of sugar or solids in the slurry. This indicated that the water molecules present in the system were the major contributors to the polarization observed. At the same concentration of solids, conductivity of the sugar containing slurries was lower than that of the non-sugar-containing starch slurries, which suggested that conductivity was mostly associated with starch. Glucose or maltose did not exert any differential effect on the swelling behavior or dielectric relaxation parameters of starch-water-sugar slurries. This project presents novel insights into the starch-water interactions occurring in the gelatinization temperature range. The results of this project can be used to develop a dielectric relaxation based technique to monitor water mobility during industrial processing of starch-based foods. Dielectric response was not unique to any of the solids used in the study suggesting that dielectric spectroscopy could be used for monitoring state of water in food systems containing different types of solids. Also, the dielectric relaxation parameters obtained in this study can be used to predict water mobility in simple food systems having water, sugar and starch as major components, and hence, can possibly be used to estimate shelf life of food products.

Frequency Modulation and Absorption Improvement of THz Micro-bolometer with Micro-bridge Structure by Spiral-Type Antennas

NASA Astrophysics Data System (ADS)

Gou, Jun; Niu, Qingchen; Liang, Kai; Wang, Jun; Jiang, Yadong

2018-03-01

Antenna-coupled micro-bridge structure is proven to be a good solution to extend infrared micro-bolometer technology for THz application. Spiral-type antennas are proposed in 25 μm × 25 μm micro-bridge structure with a single separate linear antenna, two separate linear antennas, or two connected linear antennas on the bridge legs, in addition to traditional spiral-type antenna on the support layer. The effects of structural parameters of each antenna on THz absorption of micro-bridge structure are discussed for optimized absorption of 2.52 THz wave radiated by far infrared CO2 lasers. The design of spiral-type antenna with two separate linear antennas for wide absorption peak and spiral-type antenna with two connected linear antennas for relatively stable absorption are good candidates for high absorption at low absorption frequency with a rotation angle of 360* n ( n = 1.6). Spiral-type antenna with extended legs also provides a highly integrated micro-bridge structure with fast response and a highly compatible, process-simplified way to realize the structure. This research demonstrates the design of several spiral-type antenna-coupled micro-bridge structures and provides preferred schemes for potential device applications in room temperature sensing and real-time imaging.

Frequency Modulation and Absorption Improvement of THz Micro-bolometer with Micro-bridge Structure by Spiral-Type Antennas.

PubMed

Gou, Jun; Niu, Qingchen; Liang, Kai; Wang, Jun; Jiang, Yadong

2018-03-05

Antenna-coupled micro-bridge structure is proven to be a good solution to extend infrared micro-bolometer technology for THz application. Spiral-type antennas are proposed in 25 μm × 25 μm micro-bridge structure with a single separate linear antenna, two separate linear antennas, or two connected linear antennas on the bridge legs, in addition to traditional spiral-type antenna on the support layer. The effects of structural parameters of each antenna on THz absorption of micro-bridge structure are discussed for optimized absorption of 2.52 THz wave radiated by far infrared CO 2 lasers. The design of spiral-type antenna with two separate linear antennas for wide absorption peak and spiral-type antenna with two connected linear antennas for relatively stable absorption are good candidates for high absorption at low absorption frequency with a rotation angle of 360*n (n = 1.6). Spiral-type antenna with extended legs also provides a highly integrated micro-bridge structure with fast response and a highly compatible, process-simplified way to realize the structure. This research demonstrates the design of several spiral-type antenna-coupled micro-bridge structures and provides preferred schemes for potential device applications in room temperature sensing and real-time imaging.

Research on fusion algorithm of polarization image in tetrolet domain

NASA Astrophysics Data System (ADS)

Zhang, Dexiang; Yuan, BaoHong; Zhang, Jingjing

2015-12-01

Tetrolets are Haar-type wavelets whose supports are tetrominoes which are shapes made by connecting four equal-sized squares. A fusion method for polarization images based on tetrolet transform is proposed. Firstly, the magnitude of polarization image and angle of polarization image can be decomposed into low-frequency coefficients and high-frequency coefficients with multi-scales and multi-directions using tetrolet transform. For the low-frequency coefficients, the average fusion method is used. According to edge distribution differences in high frequency sub-band images, for the directional high-frequency coefficients are used to select the better coefficients by region spectrum entropy algorithm for fusion. At last the fused image can be obtained by utilizing inverse transform for fused tetrolet coefficients. Experimental results show that the proposed method can detect image features more effectively and the fused image has better subjective visual effect

High-frequency microrheology reveals cytoskeleton dynamics in living cells

NASA Astrophysics Data System (ADS)

Rigato, Annafrancesca; Miyagi, Atsushi; Scheuring, Simon; Rico, Felix

2017-08-01

Living cells are viscoelastic materials, dominated by an elastic response on timescales longer than a millisecond. On shorter timescales, the dynamics of individual cytoskeleton filaments are expected to emerge, but active microrheology measurements on cells accessing this regime are scarce. Here, we develop high-frequency microrheology experiments to probe the viscoelastic response of living cells from 1 Hz to 100 kHz. We report the viscoelasticity of different cell types under cytoskeletal drug treatments. On previously inaccessible short timescales, cells exhibit rich viscoelastic responses that depend on the state of the cytoskeleton. Benign and malignant cancer cells revealed remarkably different scaling laws at high frequencies, providing a unique mechanical fingerprint. Microrheology over a wide dynamic range--up to the frequency characterizing the molecular components--provides a mechanistic understanding of cell mechanics.

Tonotopic reorganization and spontaneous firing in inferior colliculus during both short and long recovery periods after noise overexposure

PubMed Central

2013-01-01

Background Noise induced injury of the cochlea causes shifts in activation thresholds and changes of frequency response in the inferior colliculus (IC). Noise overexposure also induces pathological changes in the cochlea, and is highly correlated to hearing loss. However, the underlying mechanism has not been fully elucidated. In this study, we hypothesized that overexposure to noise induces substantial electrophysiological changes in the IC of guinea pigs. Results During the noise exposure experiment, the animals were undergoing a bilateral exposure to noise. Additionally, various techniques were employed including confocal microscopy for the detection of cochlea hair cells and single neuron recording for spontaneous firing activity measurement. There were alterations among three types of frequency response area (FRA) from sound pressure levels, including V-, M-, and N-types. Our results indicate that overexposure to noise generates different patterns in the FRAs. Following a short recovery (one day after the noise treatment), the percentage of V-type FRAs considerably decreased, whereas the percentage of M-types increased. This was often caused by a notch in the frequency response that occurred at 4 kHz (noise frequency). Following a long recovery from noise exposure (11–21 days), the percentage of V-types resumed to a normal level, but the portion of M-types remained high. Interestingly, the spontaneous firing in the IC was enhanced in both short and long recovery groups. Conclusion Our data suggest that noise overexposure changes the pattern of the FRAs and stimulates spontaneous firing in the IC in a unique way, which may likely relate to the mechanism of tinnitus. PMID:24320109

Ictal high frequency oscillations distinguish two types of seizure territories in humans

PubMed Central

Weiss, Shennan A.; Banks, Garrett P.; McKhann, Guy M.; Goodman, Robert R.; Emerson, Ronald G.; Trevelyan, Andrew J.

2013-01-01

High frequency oscillations have been proposed as a clinically useful biomarker of seizure generating sites. We used a unique set of human microelectrode array recordings (four patients, 10 seizures), in which propagating seizure wavefronts could be readily identified, to investigate the basis of ictal high frequency activity at the cortical (subdural) surface. Sustained, repetitive transient increases in high gamma (80–150 Hz) amplitude, phase-locked to the low-frequency (1–25 Hz) ictal rhythm, correlated with strong multi-unit firing bursts synchronized across the core territory of the seizure. These repetitive high frequency oscillations were seen in recordings from subdural electrodes adjacent to the microelectrode array several seconds after seizure onset, following ictal wavefront passage. Conversely, microelectrode recordings demonstrating only low-level, heterogeneous neural firing correlated with a lack of high frequency oscillations in adjacent subdural recording sites, despite the presence of a strong low-frequency signature. Previously, we reported that this pattern indicates a failure of the seizure to invade the area, because of a feedforward inhibitory veto mechanism. Because multi-unit firing rate and high gamma amplitude are closely related, high frequency oscillations can be used as a surrogate marker to distinguish the core seizure territory from the surrounding penumbra. We developed an efficient measure to detect delayed-onset, sustained ictal high frequency oscillations based on cross-frequency coupling between high gamma amplitude and the low-frequency (1–25 Hz) ictal rhythm. When applied to the broader subdural recording, this measure consistently predicted the timing or failure of ictal invasion, and revealed a surprisingly small and slowly spreading seizure core surrounded by a far larger penumbral territory. Our findings thus establish an underlying neural mechanism for delayed-onset, sustained ictal high frequency oscillations, and provide a practical, efficient method for using them to identify the small ictal core regions. Our observations suggest that it may be possible to reduce substantially the extent of cortical resections in epilepsy surgery procedures without compromising seizure control. PMID:24176977

The Impact of Attention on Judgments of Frequency and Duration

PubMed Central

Winkler, Isabell; Glauer, Madlen; Betsch, Tilmann; Sedlmeier, Peter

2015-01-01

Previous studies that examined human judgments of frequency and duration found an asymmetrical relationship: While frequency judgments were quite accurate and independent of stimulus duration, duration judgments were highly dependent upon stimulus frequency. A potential explanation for these findings is that the asymmetry is moderated by the amount of attention directed to the stimuli. In the current experiment, participants' attention was manipulated in two ways: (a) intrinsically, by varying the type and arousal potential of the stimuli (names, low-arousal and high-arousal pictures), and (b) extrinsically, by varying the physical effort participants expended during the stimulus presentation (by lifting a dumbbell vs. relaxing the arm). Participants processed stimuli with varying presentation frequencies and durations and were subsequently asked to estimate the frequency and duration of each stimulus. Sensitivity to duration increased for pictures in general, especially when processed under physical effort. A large effect of stimulus frequency on duration judgments was obtained for all experimental conditions, but a similar large effect of presentation duration on frequency judgments emerged only in the conditions that could be expected to draw high amounts of attention to the stimuli: when pictures were judged under high physical effort. Almost no difference in the mutual impact of frequency and duration was obtained for low-arousal or high-arousal pictures. The mechanisms underlying the simultaneous processing of frequency and duration are discussed with respect to existing models derived from animal research. Options for the extension of such models to human processing of frequency and duration are suggested. PMID:26000712

The impact of attention on judgments of frequency and duration.

PubMed

Winkler, Isabell; Glauer, Madlen; Betsch, Tilmann; Sedlmeier, Peter

2015-01-01

Previous studies that examined human judgments of frequency and duration found an asymmetrical relationship: While frequency judgments were quite accurate and independent of stimulus duration, duration judgments were highly dependent upon stimulus frequency. A potential explanation for these findings is that the asymmetry is moderated by the amount of attention directed to the stimuli. In the current experiment, participants' attention was manipulated in two ways: (a) intrinsically, by varying the type and arousal potential of the stimuli (names, low-arousal and high-arousal pictures), and (b) extrinsically, by varying the physical effort participants expended during the stimulus presentation (by lifting a dumbbell vs. relaxing the arm). Participants processed stimuli with varying presentation frequencies and durations and were subsequently asked to estimate the frequency and duration of each stimulus. Sensitivity to duration increased for pictures in general, especially when processed under physical effort. A large effect of stimulus frequency on duration judgments was obtained for all experimental conditions, but a similar large effect of presentation duration on frequency judgments emerged only in the conditions that could be expected to draw high amounts of attention to the stimuli: when pictures were judged under high physical effort. Almost no difference in the mutual impact of frequency and duration was obtained for low-arousal or high-arousal pictures. The mechanisms underlying the simultaneous processing of frequency and duration are discussed with respect to existing models derived from animal research. Options for the extension of such models to human processing of frequency and duration are suggested.

Changes in the intensity of Mediterranean precipitation: a comparison of east/west trends and their causes

NASA Astrophysics Data System (ADS)

Goodess, C. M.; Jones, P. D.

2003-04-01

Changes in the frequency and intensity of precipitation over the last 40 years have been investigated for the Iberian Peninsula and Greece. Over much of the Mediterranean the general tendency is towards decreasing precipitation, but the pattern of change is complex, particularly with respect to extremes. Over most of the Iberian Peninsula, the last 40 years has seen a trend towards more, but less wet rain days. However, in southeast Spain, the reverse has occurred, with more wet days with high precipitation amounts. Over Greece, the main tendency is towards fewer rain days, with little change in rain day amount, which is strongest over the Ionian and Aegean Seas and in winter. A few places, such as Rhodes, do however, show a weak trend towards more intense precipitation events in autumn. The precipitation changes observed over the Iberian Peninsula can, in part, be explained by changes in atmospheric circulation. They are associated with a decrease in the frequency of cyclonic circulation types and increases in the frequency of anticyclonic, easterly and south-easterly types (which can in turn be linked with changes in the intensity of the North Atlantic Oscillation and the frequency and intensity of Mediterranean and Atlantic cyclones). However, precipitation trends simulated by regression models with circulation-type frequency as the predictor variables are weaker than observed. The observed changes in circulation-type frequency over Greece (such as the increase in the frequency of the 'high-precipitation' cyclonic types and decrease in the 'low-precipitation' anticyclonic types) indicate an increase in precipitation. This is in contrast to the observed precipitation decreases. All the regression models underestimate year-to-year variability, and have problems in reproducing the observed trends. The common problems in both regions indicate that different forms of model may be required. The finding that the selected predictor variables are more successful at reproducing the observed precipitation trends in Spain than Greece, indicates different underlying physical processes which require further investigation. Goodess, CM and Jones, PD, 2002: Links between circulation and changes in the characteristics of Iberian precipitation, Int. J. Climatol. 22, 1593-1615. Acknowledgements: This work (http://www.cru.uea.ac.uk/~clareg/nerc.htm) was funded by the Commission of the European Union as part of the ACCORD project and by the UK Natural Environment Research Council.

Radar response to vegetation. [soil moisture mapping via microwave backscattering

NASA Technical Reports Server (NTRS)

Ulaby, F. T.

1975-01-01

Active microwave measurements of vegetation backscatter were conducted to determine the utility of radar in mapping soil moisture through vegetation and mapping crop types. Using a truck-mounted boom, spectral response data were obtained for four crop types (corn, milo, soybeans, and alfalfa) over the 4-8 GHz frequency band, at incidence angles of 0 to 70 degrees in 10-degree steps, and for all four linear polarization combinations. Based on a total of 125 data sets covering a wide range of soil moisture, content, system design criteria are proposed for each of the aforementioned objectives. Quantitative soil moisture determination was best achieved at the lower frequency end of the 4-8 GHz band using HH polarized waves in the 5- to 15-degree incidence angle range. A combination of low and high frequency measurements are suggested for classifying crop types. For crop discrimination, a dual-frequency dual-polarization (VV and cross) system operating at incidence angles above 40 degrees is suggested.

Improved fabrication of focused single element P(VDF–TrFE) transducer for high frequency ultrasound applications

PubMed Central

Jeong, Jong Seob; Shung, K. Kirk

2013-01-01

We present an improved fabrication technique for the focused single element poly (vinylidene fluoride–trifluoroethylene) P(VDF–TrFE) transducer. In this work, a conductive epoxy for a backing layer was directly bonded to the 25 μm thick P(VDF–TrFE) film and thus made it easy to conform the aperture of the P(VDF–TrFE) transducer. Two prototype focused P(VDF–TrFE) transducers with disk- and ring-type aperture were fabricated and their performance was evaluated using the UBM (Ultrasound Biomicroscopy) system with a wire phantom. All transducers had a spherically focused aperture with a low f-number (focal depth/aperture size = 1). The center frequency of the disk-type P(VDF–TrFE) transducer was 23 MHz and −6 dB bandwidth was 102%. The ring-type P(VDF–TrFE) transducer had 20 MHz center frequency and −6 dB bandwidth of 103%. The measured pulse echo signal had reduced reverberation due to no additional adhesive layer between the P(VDF–TrFE) film and the backing layer. Hence, the proposed method is promising to fabricate a single element transducer using P(VDF–TrFE) film for high frequency applications. PMID:23021238

Model reductions using a projection formulation

NASA Technical Reports Server (NTRS)

De Villemagne, Christian; Skelton, Robert E.

1987-01-01

A new methodology for model reduction of MIMO systems exploits the notion of an oblique projection. A reduced model is uniquely defined by a projector whose range space and orthogonal to the null space are chosen among the ranges of generalized controllability and observability matrices. The reduced order models match various combinations (chosen by the designer) of four types of parameters of the full order system associated with (1) low frequency response, (2) high frequency response, (3) low frequency power spectral density, and (4) high frequency power spectral density. Thus, the proposed method is a computationally simple substitute for many existing methods, has an extreme flexibility to embrace combinations of existing methods and offers some new features.

Mechanisms of Left-Right Coordination in Mammalian Locomotor Pattern Generation Circuits: A Mathematical Modeling View

PubMed Central

Talpalar, Adolfo E.; Rybak, Ilya A.

2015-01-01

The locomotor gait in limbed animals is defined by the left-right leg coordination and locomotor speed. Coordination between left and right neural activities in the spinal cord controlling left and right legs is provided by commissural interneurons (CINs). Several CIN types have been genetically identified, including the excitatory V3 and excitatory and inhibitory V0 types. Recent studies demonstrated that genetic elimination of all V0 CINs caused switching from a normal left-right alternating activity to a left-right synchronized “hopping” pattern. Furthermore, ablation of only the inhibitory V0 CINs (V0D subtype) resulted in a lack of left-right alternation at low locomotor frequencies and retaining this alternation at high frequencies, whereas selective ablation of the excitatory V0 neurons (V0V subtype) maintained the left–right alternation at low frequencies and switched to a hopping pattern at high frequencies. To analyze these findings, we developed a simplified mathematical model of neural circuits consisting of four pacemaker neurons representing left and right, flexor and extensor rhythm-generating centers interacting via commissural pathways representing V3, V0D, and V0V CINs. The locomotor frequency was controlled by a parameter defining the excitation of neurons and commissural pathways mimicking the effects of N-methyl-D-aspartate on locomotor frequency in isolated rodent spinal cord preparations. The model demonstrated a typical left-right alternating pattern under control conditions, switching to a hopping activity at any frequency after removing both V0 connections, a synchronized pattern at low frequencies with alternation at high frequencies after removing only V0D connections, and an alternating pattern at low frequencies with hopping at high frequencies after removing only V0V connections. We used bifurcation theory and fast-slow decomposition methods to analyze network behavior in the above regimes and transitions between them. The model reproduced, and suggested explanation for, a series of experimental phenomena and generated predictions available for experimental testing. PMID:25970489

High frequency of a single nucleotide substitution (c.-6-180T>G) of the canine MDR1/ABCB1 gene associated with phenobarbital-resistant idiopathic epilepsy in Border Collie dogs.

PubMed

Mizukami, Keijiro; Yabuki, Akira; Chang, Hye-Sook; Uddin, Mohammad Mejbah; Rahman, Mohammad Mahbubur; Kushida, Kazuya; Kohyama, Moeko; Yamato, Osamu

2013-01-01

A single nucleotide substitution (c.-6-180T>G) associated with resistance to phenobarbital therapy has been found in the canine MDR1/ABCB1 gene in Border Collies with idiopathic epilepsy. In the present study, a PCR-restriction fragment length polymorphism assay was developed for genotyping this mutation, and a genotyping survey was carried out in a population of 472 Border Collies in Japan to determine the current allele frequency. The survey demonstrated the frequencies of the T/T wild type, T/G heterozygote, and G/G mutant homozygote to be 60.0%, 30.3%, and 9.8%, respectively, indicating that the frequency of the mutant G allele is extremely high (24.9%) in Border Collies. The results suggest that this high mutation frequency of the mutation is likely to cause a high prevalence of phenobarbital-resistant epilepsy in Border Collies.

High Frequency of a Single Nucleotide Substitution (c.-6-180T>G) of the Canine MDR1/ABCB1 Gene Associated with Phenobarbital-Resistant Idiopathic Epilepsy in Border Collie Dogs

PubMed Central

Mizukami, Keijiro; Yabuki, Akira; Chang, Hye-Sook; Uddin, Mohammad Mejbah; Rahman, Mohammad Mahbubur; Kushida, Kazuya; Kohyama, Moeko

2013-01-01

A single nucleotide substitution (c.-6-180T>G) associated with resistance to phenobarbital therapy has been found in the canine MDR1/ABCB1 gene in Border Collies with idiopathic epilepsy. In the present study, a PCR-restriction fragment length polymorphism assay was developed for genotyping this mutation, and a genotyping survey was carried out in a population of 472 Border Collies in Japan to determine the current allele frequency. The survey demonstrated the frequencies of the T/T wild type, T/G heterozygote, and G/G mutant homozygote to be 60.0%, 30.3%, and 9.8%, respectively, indicating that the frequency of the mutant G allele is extremely high (24.9%) in Border Collies. The results suggest that this high mutation frequency of the mutation is likely to cause a high prevalence of phenobarbital-resistant epilepsy in Border Collies. PMID:24302812

Epoxy-based hydrogels investigated by high-frequency dielectric relaxation spectroscopy.

PubMed

Krakovský, Ivan; Shikata, Toshiyuki; Hasegawa, Ryuta

2013-11-14

Using high-frequency dielectric relaxation spectroscopy, nanophase-separated structures of epoxy-based hydrogels were investigated as a function of water content at 25 °C. The dielectric spectra resulting from the hydrogels were reasonably decomposed into two Debye-type and two Cole-Cole-type relaxation modes. The fastest Debye-type mode, found at 8.3 ps, was attributed to the rotational relaxation process of free water molecules in the bulk state. The other Debye-type mode, at ca. 20-34 ps, originates from the exchange process of water molecules that are hydrogen-bonded to the hydrophilic epoxy network portions for free bulk ones. The first Cole-Cole-type mode observed, at ca. 20-370 ps, was assigned to the complicated dynamics for electric dipole moments of the hydrophilic groups in the epoxy networks (mainly monomeric oxyethylene units). The slowest major Cole-Cole-type mode, at 5-29 ns, was attributed to the Maxwell-Wagner-Sillars polarization process and confirmed the presence of the nanophase-separated structures as revealed by the previous small-angle neutron scattering experiments.

Dynamic response characteristics of high temperature superconducting maglev systems: Comparison between Halbach-type and normal permanent magnet guideways

NASA Astrophysics Data System (ADS)

Wang, B.; Zheng, J.; Che, T.; Zheng, B. T.; Si, S. S.; Deng, Z. G.

2015-12-01

The permanent magnet guideway (PMG) is very important for the performance of the high temperature superconducting (HTS) system in terms of electromagnetic force and operational stability. The dynamic response characteristics of a HTS maglev model levitating on two types of PMG, which are the normal PMG with iron flux concentration and Halbach-type PMG, were investigated by experiments. The dynamic signals for different field-cooling heights (FCHs) and loading/unloading processes were acquired and analyzed by a vibration analyzer and laser displacement sensors. The resonant frequency, stiffness and levitation height of the model were discussed. It was found that the maglev model on the Halbach-type PMG has higher resonant frequency and higher vertical stiffness compared with the normal PMG. However, the low lateral stiffness of the model on the Halbach-type PMG indicates poor lateral stability. Besides, the Halbach-type PMG has better loading capacity than the normal PMG. These results are helpful to design a suitable PMG for the HTS system in practical applications.

Influence of solar variability on the occurrence of central European weather types from 1763 to 2009

NASA Astrophysics Data System (ADS)

Schwander, Mikhaël; Rohrer, Marco; Brönnimann, Stefan; Malik, Abdul

2017-09-01

The impact of solar variability on weather and climate in central Europe is still not well understood. In this paper we use a new time series of daily weather types to analyse the influence of the 11-year solar cycle on the tropospheric weather of central Europe. We employ a novel, daily weather type classification over the period 1763-2009 and investigate the occurrence frequency of weather types under low, moderate, and high solar activity level. Results show a tendency towards fewer days with westerly and west-southwesterly flow over central Europe under low solar activity. In parallel, the occurrence of northerly and easterly types increases. For the 1958-2009 period, a more detailed view can be gained from reanalysis data. Mean sea level pressure composites under low solar activity also show a reduced zonal flow, with an increase of the mean blocking frequency between Iceland and Scandinavia. Weather types and reanalysis data show that the 11-year solar cycle influences the late winter atmospheric circulation over central Europe with colder (warmer) conditions under low (high) solar activity.

Radio frequency self-resonant coil for contactless AC-conductivity in 100 T class ultra-strong pulse magnetic fields

NASA Astrophysics Data System (ADS)

Nakamura, D.; Altarawneh, M. M.; Takeyama, S.

2018-03-01

A contactless measurement system of electrical conductivity was developed for application under pulsed high magnetic fields over 100 T by using a self-resonant-type, high-frequency circuit. Electromagnetic fields in the circuit were numerically analysed by the finite element method, to show how the resonant power spectra of the circuit depends on the electrical conductivity of a sample set on the probe-coil. The performance was examined using a high-temperature cuprate superconductor, La2-x Sr x CuO4, in magnetic fields up to 102 T with a high frequency of close to 800 MHz. As a result, the upper critical field could be determined with a good signal-to-noise ratio.

Broadband active electrically small superconductor antennas

NASA Astrophysics Data System (ADS)

Kornev, V. K.; Kolotinskiy, N. V.; Sharafiev, A. V.; Soloviev, I. I.; Mukhanov, O. A.

2017-10-01

A new type of broadband active electrically small antenna (ESA) based on superconducting quantum arrays (SQAs) has been proposed and developed. These antennas are capable of providing both sensing and amplification of broadband electromagnetic signals with a very high spurious-free dynamic range (SFDR)—up to 100 dB (and even more)—with high sensitivity. The frequency band can range up to tens of gigahertz, depending on Josephson junction characteristic frequency, set by fabrication. In this paper we review theoretical and experimental studies of SQAs and SQA-based antenna prototypes of both transformer and transformer-less types. The ESA prototypes evaluated were fabricated using a standard Nb process with critical current density 4.5 kA cm-2. Measured device characteristics, design issues and comparative analysis of various ESA types, as well as requirements for interfaces, are reviewed and discussed.

Dynamics of heart rate variability in patients with type 2 diabetes mellitus during spinal anaesthesia: prospective observational study.

PubMed

Lee, Su Hyun; Lee, Dong Hoon; Ha, Dong Hoon; Oh, Young Jun

2015-10-08

Little is known about the changes in autonomic function during spinal anaesthesia in type 2 diabetic patients. The purpose of the study was to assess the influence of spinal anaesthesia on the heart rate variability in type 2 diabetic patients according to the glycated hemoglobin (HbA1c) level. Sixty-six patients who were scheduled for elective orthostatic lower limb surgery were assigned to three groups (n = 22, each) according to HbA1c; controlled diabetes mellitus (HbA1c < 7 %), uncontrolled diabetes mellitus (HbA1c > 7 %) and the control group. The heart rate variability was measured 10 min before (T0), and at10 min (T1), 20 min (T2) and 30 min (T3) after spinal anaesthesia. Before spinal anaesthesia, total, low-and high-frequency power were significantly lower in the uncontrolled diabetec group than in other group (p < 0.05). During spinal anaesthesia, total, low- and high-frequency powers were did not change in the uncontrolled diabetec group while the low-frequency power in the controlled diabetec group was significantly depressed (p < 0.05). The ratio of low-to high-frequency was comparable among the groups, while it was reduced at T1-2 than at T0 in all the groups. The blood pressures were higher in the uncontrolled diabetec group than in the other groups. Spinal anaesthesia had an influence on the cardiac autonomic modulation in controlled diabetec patients, but not in uncontrolled diabetec patients. There were no differences in all haemodynamic variables during an adequate level of spinal anaesthesia in controlled and uncontrolled type 2 DM. ClinicalTrials.gov NCT02137057.

Two-stage high frequency pulse tube refrigerator with base temperature below 10 K

NASA Astrophysics Data System (ADS)

Chen, Liubiao; Wu, Xianlin; Liu, Sixue; Zhu, Xiaoshuang; Pan, Changzhao; Guo, Jia; Zhou, Yuan; Wang, Junjie

2017-12-01

This paper introduces our recent experimental results of pulse tube refrigerator driven by linear compressor. The working frequency is 23-30 Hz, which is much higher than the G-M type cooler (the developed cryocooler will be called high frequency pulse tube refrigerator in this paper). To achieve a temperature below 10 K, two types of two-stage configuration, gas coupled and thermal coupled, have been designed, built and tested. At present, both types can achieve a no-load temperature below 10 K by using only one compressor. As to gas-coupled HPTR, the second stage can achieve a cooling power of 16 mW/10K when the first stage applied a 400 mW heat load at 60 K with a total input power of 400 W. As to thermal-coupled HPTR, the designed cooling power of the first stage is 10W/80K, and then the temperature of the second stage can get a temperature below 10 K with a total input power of 300 W. In the current preliminary experiment, liquid nitrogen is used to replace the first coaxial configuration as the precooling stage, and a no-load temperature 9.6 K can be achieved with a stainless steel mesh regenerator. Using Er3Ni sphere with a diameter about 50-60 micron, the simulation results show it is possible to achieve a temperature below 8 K. The configuration, the phase shifters and the regenerative materials of the developed two types of two-stage high frequency pulse tube refrigerator will be discussed, and some typical experimental results and considerations for achieving a better performance will also be presented in this paper.

Voluntary Movement Frequencies in Submaximal One- and Two-Legged Knee Extension Exercise and Pedaling

PubMed Central

Stang, Julie; Wiig, Håvard; Hermansen, Marte; Hansen, Ernst Albin

2016-01-01

Understanding of behavior and control of human voluntary rhythmic stereotyped leg movements is useful in work to improve performance, function, and rehabilitation of exercising, healthy, and injured humans. The present study aimed at adding to the existing understanding within this field. To pursue the aim, correlations between freely chosen movement frequencies in relatively simple, single-joint, one- and two-legged knee extension exercise were investigated. The same was done for more complex, multiple-joint, one- and two-legged pedaling. These particular activities were chosen because they could be considered related to some extent, as they shared a key aspect of knee extension, and because they at the same time were different. The activities were performed at submaximal intensities, by healthy individuals (n = 16, thereof eight women; 23.4 ± 2.7 years; 1.70 ± 0.11 m; 68.6 ± 11.2 kg). High and fair correlations (R-values of 0.99 and 0.75) occurred between frequencies generated with the dominant leg and the nondominant leg during knee extension exercise and pedaling, respectively. Fair to high correlations (R-values between 0.71 and 0.95) occurred between frequencies performed with each of the two legs in an activity, and the two-legged frequency performed in the same type of activity. In general, the correlations were higher for knee extension exercise than for pedaling. Correlations between knee extension and pedaling frequencies were of modest occurrence. The correlations between movement frequencies generated separately by each of the legs might be interpreted to support the following working hypothesis, which was based on existing literature. It is likely that involved central pattern generators (CPGs) of the two legs share a common frequency generator or that separate frequency generators of each leg are attuned via interneuronal connections. Further, activity type appeared to be relevant. Thus, the apparent common rhythmogenesis for the two legs appeared to be stronger for the relatively simple single-joint activity of knee extension exercise as compared to the more complex multi-joint activity of pedaling. Finally, it appeared that the shared aspect of knee extension in the related types of activities of knee extension exercise and pedaling was insufficient to cause obvious correlations between generated movement frequencies in the two types of activities. PMID:26973486

CMOS compatible fabrication process of MEMS resonator for timing reference and sensing application

NASA Astrophysics Data System (ADS)

Huynh, Duc H.; Nguyen, Phuong D.; Nguyen, Thanh C.; Skafidas, Stan; Evans, Robin

2015-12-01

Frequency reference and timing control devices are ubiquitous in electronic applications. There is at least one resonator required for each of this device. Currently electromechanical resonators such as crystal resonator, ceramic resonator are the ultimate choices. This tendency will probably keep going for many more years. However, current market demands for small size, low power consumption, cheap and reliable products, has divulged many limitations of this type of resonators. They cannot be integrated into standard CMOS (Complement metaloxide- semiconductor) IC (Integrated Circuit) due to material and fabrication process incompatibility. Currently, these devices are off-chip and they require external circuitries to interface with the ICs. This configuration significantly increases the overall size and cost of the entire electronic system. In addition, extra external connection, especially at high frequency, will potentially create negative impacts on the performance of the entire system due to signal degradation and parasitic effects. Furthermore, due to off-chip packaging nature, these devices are quite expensive, particularly for high frequency and high quality factor devices. To address these issues, researchers have been intensively studying on an alternative for type of resonator by utilizing the new emerging MEMS (Micro-electro-mechanical systems) technology. Recent progress in this field has demonstrated a MEMS resonator with resonant frequency of 2.97 GHz and quality factor (measured in vacuum) of 42900. Despite this great achievement, this prototype is still far from being fully integrated into CMOS system due to incompatibility in fabrication process and its high series motional impedance. On the other hand, fully integrated MEMS resonator had been demonstrated but at lower frequency and quality factor. We propose a design and fabrication process for a low cost, high frequency and a high quality MEMS resonator, which can be integrated into a standard CMOS IC. This device is expected to operate in hundreds of Mhz frequency range; quality factor surpasses 10000 and series motional impedance low enough that could be matching into conventional system without enormous effort. This MEMS resonator can be used in the design of many blocks in wireless and RF (Radio Frequency) systems such as low phase noise oscillator, band pass filter, power amplifier and in many sensing application.

High resolution observations with Artemis-IV and the NRH. I. Type IV associated narrow-band bursts

NASA Astrophysics Data System (ADS)

Bouratzis, C.; Hillaris, A.; Alissandrakis, C. E.; Preka-Papadema, P.; Moussas, X.; Caroubalos, C.; Tsitsipis, P.; Kontogeorgos, A.

2016-02-01

Context. Narrow-band bursts appear on dynamic spectra from microwave to decametric frequencies as fine structures with very small duration and bandwidth. They are believed to be manifestations of small scale energy release through magnetic reconnection. Aims: We analyzed 27 metric type IV events with embedded narrow-band bursts, which were observed by the ARTEMIS-IV radio spectrograph from 30 June 1999 to 1 August 2010. We examined the morphological characteristics of isolated narrow-band structures (mostly spikes) and groups or chains of structures. Methods: The events were recorded with the SAO high resolution (10 ms cadence) receiver of ARTEMIS-IV in the 270-450 MHz range. We measured the duration, spectral width, and frequency drift of ~12 000 individual narrow-band bursts, groups, and chains. Spike sources were imaged with the Nançay radioheliograph (NRH) for the event of 21 April 2003. Results: The mean duration of individual bursts at fixed frequency was ~100 ms, while the instantaneous relative bandwidth was ~2%. Some bursts had measurable frequency drift, either positive or negative. Quite often spikes appeared in chains, which were closely spaced in time (column chains) or in frequency (row chains). Column chains had frequency drifts similar to type-IIId bursts, while most of the row chains exhibited negative frequently drifts with a rate close to that of fiber bursts. From the analysis of NRH data, we found that spikes were superimposed on a larger, slowly varying, background component. They were polarized in the same sense as the background source, with a slightly higher degree of polarization of ~65%, and their size was about 60% of their size in total intensity. Conclusions: The duration and bandwidth distributions did not show any clear separation in groups. Some chains tended to assume the form of zebra, lace stripes, fiber bursts, or bursts of the type-III family, suggesting that such bursts might be resolved in spikes when viewed with high resolution. The NRH data indicate that the spikes are not fluctuations of the background, but represent additional emission such as what would be expected from small-scale reconnection.

Generation of 46 W green-light by frequency doubling of 96 W picosecond unpolarized Yb-doped fiber amplifier

NASA Astrophysics Data System (ADS)

Qi, Yaoyao; Yu, Haijuan; Zhang, Jingyuan; Zhang, Ling; He, Chaojian; Lin, Xuechun

2018-05-01

We demonstrated a high efficiency and high average power picosecond green light source based on SHG (second harmonic generation) of an unpolarized ytterbium-doped fiber amplifier chain. Using single-pass frequency doubling in two temperature-tuned type-I phase-matching LBO crystals, we were able to generate 46 W, >70 ps pulses at 532 nm from a fundamental beam at 1064 nm, whose output is 96 W, 4.8 μJ, with a repetition frequency of 20 MHz and nearly diffraction limited. The optical conversion efficiency was ∼48% in a highly compact design. To the best of our knowledge, this is the first reported on ps green source through SHG of an unpolarized fiber laser with such a high output and high efficiency.

Effects of food type, feeding frequency, and temperature on juvenile survival and growth of Marisa cornuarietis (Mollusca: Gastropoda).

PubMed

Selck, Henriette; Aufderheide, John; Pounds, Nadine; Staples, Charles; Caspers, Norbert; Forbes, Valery

2006-06-01

The present experiments are part of a larger study designed to investigate the influence of husbandry parameters on the life history of the ramshorn snail, Marisa cornuarietis, in order to identify suitable husbandry conditions for maintaining multi-generation populations in the laboratory for use in ecotoxicological testing. In this paper we focus on the effects of a combination of food types and feeding frequencies (i.e., the frequency with which the snails were offered food) on juvenile growth and survival at different temperatures. Offspring produced in the laboratory by wild specimens of M. cornuarietis, from Puerto Rico, were used to test the effects of three types of food (lettuce, alginate with fish food, alginate with snail mix) fed at three frequencies (given ad libitum on 4/4, 2/4, or 1/4 d) on juvenile survival and growth. The 4-d feeding regimens were repeated four times, giving a total of 16 d for the experiments. The experiments were conducted at two temperatures (22 degrees and 25 degrees C) under a 12 h light:12 h dark photoperiod. Juvenile growth rates increased with increasing feeding frequency for all food types. The most rapid growth rates occurred in the high-frequency lettuce treatments and the slowest growth rates in the low-frequency lettuce and alginate with snail mix treatments. Juvenile snails grew faster at 25 degrees than at 22 degrees C, and mortality was about twice as high at the lower temperature. Growth rates were used to provide a rough estimate of time to maturity, which was determined to take about twice as long at 22 degrees than at 25 degrees C. The results showed that lettuce is the best food if supplied in abundance, but effects on growth are very dependent on feeding frequency and temperature. We conclude that 25 degrees C is a more appropriate temperature for maintaining populations than 22 degrees C, that lettuce provides a suitable food source, and that food should be supplied continuously for husbandry and toxicity testing of populations of M. cornuarietis.

High-Resolution Audio with Inaudible High-Frequency Components Induces a Relaxed Attentional State without Conscious Awareness.

PubMed

Kuribayashi, Ryuma; Nittono, Hiroshi

2017-01-01

High-resolution audio has a higher sampling frequency and a greater bit depth than conventional low-resolution audio such as compact disks. The higher sampling frequency enables inaudible sound components (above 20 kHz) that are cut off in low-resolution audio to be reproduced. Previous studies of high-resolution audio have mainly focused on the effect of such high-frequency components. It is known that alpha-band power in a human electroencephalogram (EEG) is larger when the inaudible high-frequency components are present than when they are absent. Traditionally, alpha-band EEG activity has been associated with arousal level. However, no previous studies have explored whether sound sources with high-frequency components affect the arousal level of listeners. The present study examined this possibility by having 22 participants listen to two types of a 400-s musical excerpt of French Suite No. 5 by J. S. Bach (on cembalo, 24-bit quantization, 192 kHz A/D sampling), with or without inaudible high-frequency components, while performing a visual vigilance task. High-alpha (10.5-13 Hz) and low-beta (13-20 Hz) EEG powers were larger for the excerpt with high-frequency components than for the excerpt without them. Reaction times and error rates did not change during the task and were not different between the excerpts. The amplitude of the P3 component elicited by target stimuli in the vigilance task increased in the second half of the listening period for the excerpt with high-frequency components, whereas no such P3 amplitude change was observed for the other excerpt without them. The participants did not distinguish between these excerpts in terms of sound quality. Only a subjective rating of inactive pleasantness after listening was higher for the excerpt with high-frequency components than for the other excerpt. The present study shows that high-resolution audio that retains high-frequency components has an advantage over similar and indistinguishable digital sound sources in which such components are artificially cut off, suggesting that high-resolution audio with inaudible high-frequency components induces a relaxed attentional state without conscious awareness.

Stem Cell Physics. Laser Manipulation of Blood Types: Laser-Stripping-Away of Red Blood Cell Surface Antigens

NASA Astrophysics Data System (ADS)

Stefan, V. Alexander

2014-03-01

A novel mechanism of importance for the transfusion medicine[2] is proposed. The interaction of ultrashort wavelength multilaser beams with the flowing blood thin films can lead to a conversion of blood types A, B, and AB into O type.[3] The stripping away of antigens is done by the scanning-multiple-lasers of a high repetition rate in the blue-purple frequency domain. The guiding-lasers are in the red-green frequency domain. The laser force, (parametric interaction with the antigen eigen-oscillation),[4] upon the antigen protein molecule must exceed its weight. Supported by Nikola Tesla Labs, La Jolla, CA.

Frequency and expression of mutacin biosynthesis genes in isolates of Streptococcus mutans with different mutacin-producing phenotypes.

PubMed

Kamiya, Regianne Umeko; Höfling, José Francisco; Gonçalves, Reginaldo Bruno

2008-05-01

The aim of this study was to analyse the frequency and expression of biosynthesis genes in 47 Streptococcus mutans isolates with different mutacin-producing phenotypes. Detection of the frequency and expression of genes encoding mutacin types I, II, III and IV were carried out by PCR and semi-quantitative RT-PCR, respectively, using primers specific for each type of biosynthesis gene. In addition, a further eight genes encoding putative bacteriocins, designated bsm 283, bsm 299, bsm 423, bsm 1889c, bsm 1892c, bsm 1896, bsm 1906c and bsm 1914, were also screened. There was a high phenotypic diversity; some Streptococcus mutans isolates presented broad antimicrobial spectra against other Streptococcus mutans clinical isolates, including bacteria resistant to common antibiotics, as well as Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Streptococcus pyogenes. The expression frequency of the bsm gene was higher than that of the previously characterized mutacins (I-IV). There was no positive correlation between the number of indicator strains inhibited (antimicrobial spectra) and the number of biosynthesis genes expressed (Spearman correlation test, r=-0.03, P>0.05). In conclusion, the high diversity of mutacin-producing phenotypes, associated with high frequency of expression of the biosynthesis genes screened, reveals a broad repertoire of genetic determinants encoding antimicrobial peptides that can act in different combinations.

STEREO observations of HD90386 (RX Sex): a δ-Scuti or a hybrid star?

NASA Astrophysics Data System (ADS)

Ozuyar, D.; Stevens, I. R.; Whittaker, G.; Sangaralingam, V.

2016-04-01

HD90386 is a rarely studied bright A2V type δ Scuti star (V = 6.66 mag). It displays short-term light curve variations which are originated due to either a beating phenomenon or a non-periodic variation. In this paper, we presented high-precision photometric data of HD90386 taken by the STEREO satellite between 2007 and 2011 to shed light on its internal structure and evolution stage. From the frequency analysis of the four-year data, we detected that HD90386 had at least six different frequencies between 1 and 15 c d-1. The most dominant frequencies were found at around 10.25258 c d-1 (A ∼ 1.92 mmag) and 12.40076 c d-1 (A ∼ 0.61 mmag). Based on the ratio between these frequencies, the star was considered as an overtone pulsator. The variation in pulsation period over 35 years was calculated to be dP/Pdt = 5.39(2) x 10-3 yr-1. Other variabilities at around 1.0 c d-1 in the amplitude spectrum of HD90386 were also discussed. In order to explain these variabilities, possible rotational effects and γ Dor type variations were focused. Consequently, depending on the rotation velocity of HD90386, we speculated that these changes might be related to γ Dor type high-order g-modes shifted to the higher frequencies and that HD90386 might be a hybrid star.

Attending Globally or Locally: Incidental Learning of Optimal Visual Attention Allocation

ERIC Educational Resources Information Center

Beck, Melissa R.; Goldstein, Rebecca R.; van Lamsweerde, Amanda E.; Ericson, Justin M.

2018-01-01

Attention allocation determines the information that is encoded into memory. Can participants learn to optimally allocate attention based on what types of information are most likely to change? The current study examined whether participants could incidentally learn that changes to either high spatial frequency (HSF) or low spatial frequency (LSF)…

Flow sensing by pinniped whiskers

PubMed Central

Miersch, L.; Hanke, W.; Wieskotten, S.; Hanke, F. D.; Oeffner, J.; Leder, A.; Brede, M.; Witte, M.; Dehnhardt, G.

2011-01-01

Beside their haptic function, vibrissae of harbour seals (Phocidae) and California sea lions (Otariidae) both represent highly sensitive hydrodynamic receptor systems, although their vibrissal hair shafts differ considerably in structure. To quantify the sensory performance of both hair types, isolated single whiskers were used to measure vortex shedding frequencies produced in the wake of a cylinder immersed in a rotational flow tank. These measurements revealed that both whisker types were able to detect the vortex shedding frequency but differed considerably with respect to the signal-to-noise ratio (SNR). While the signal detected by sea lion whiskers was substantially corrupted by noise, harbour seal whiskers showed a higher SNR with largely reduced noise. However, further analysis revealed that in sea lion whiskers, each noise signal contained a dominant frequency suggested to function as a characteristic carrier signal. While in harbour seal whiskers the unique surface structure explains its high sensitivity, this more or less steady fundamental frequency might represent the mechanism underlying hydrodynamic reception in the fast swimming sea lion by being modulated in response to hydrodynamic stimuli impinging on the hair. PMID:21969689

Characteristic analysis of diaphragm-type transducer that is thick relative to its size

NASA Astrophysics Data System (ADS)

Ishiguro, Yuya; Zhu, Jing; Tagawa, Norio; Okubo, Tsuyoshi; Okubo, Kan

2017-07-01

In recent years, high-performance piezoelectric micromachined ultrasonic transducers (PMUTs) have been fabricated by micro electro mechanical systems (MEMS) technology. For high-resolution imaging, it is important to broaden the frequency bandwidth. By reducing the diaphragm size to increase the resonance frequency, the film thickness becomes relatively larger and hence the transmitting and receiving characteristics may different from those of a usual thin diaphragm. In this study, we examine the performance of a square-diaphragm-type lead zirconate titanate (PZT) transducer through simulations. To realize the desired resonance frequency of 20 MHz, firstly, the diaphragm size and the thickness of the layers of PZT and Si constituting a PMUT are examined, and then, three PZT/Si models with different thicknesses are selected. Subsequently, using the models, we analyze the transmitting efficiency, transmitting bandwidth, receiving sensitivity (piezoelectric voltage/electric charge), and receiving bandwidth using an FEM simulator. It is found that the proposed models can transmit ultrasound independently of the diaphragm vibration and have wide bandwidth of the receiving frequency as compared with that of a typical PMUT.

High Bypass Ratio Jet Noise Reduction and Installation Effects Including Shielding Effectiveness

NASA Technical Reports Server (NTRS)

Thomas, Russell H.; Czech, Michael J.; Doty, Michael J.

2013-01-01

An experimental investigation was performed to study the propulsion airframe aeroacoustic installation effects of a separate flow jet nozzle with a Hybrid Wing Body aircraft configuration where the engine is installed above the wing. Prior understanding of the jet noise shielding effectiveness was extended to a bypass ratio ten application as a function of nozzle configuration, chevron type, axial spacing, and installation effects from additional airframe components. Chevron types included fan chevrons that are uniform circumferentially around the fan nozzle and T-fan type chevrons that are asymmetrical circumferentially. In isolated testing without a pylon, uniform chevrons compared to T-fan chevrons showed slightly more low frequency reduction offset by more high frequency increase. Phased array localization shows that at this bypass ratio chevrons still move peak jet noise source locations upstream but not to nearly the extent, as a function of frequency, as for lower bypass ratio jets. For baseline nozzles without chevrons, the basic pylon effect has been greatly reduced compared to that seen for lower bypass ratio jets. Compared to Tfan chevrons without a pylon, the combination with a standard pylon results in more high frequency noise increase and an overall higher noise level. Shielded by an airframe surface 2.17 fan diameters from nozzle to airframe trailing edge, the T-fan chevron nozzle can produce reductions in jet noise of as much as 8 dB at high frequencies and upstream angles. Noise reduction from shielding decreases with decreasing frequency and with increasing angle from the jet inlet. Beyond an angle of 130 degrees there is almost no noise reduction from shielding. Increasing chevron immersion more than what is already an aggressive design is not advantageous for noise reduction. The addition of airframe control surfaces, including vertical stabilizers and elevon deflection, showed only a small overall impact. Based on the test results, the best overall nozzle configuration design was selected for application to the N2A Hybrid Wing Body concept that will be the subject of the NASA Langley 14 by 22 Foot Subsonic Tunnel high fidelity aeroacoustic characterization experiment. The best overall nozzle selected includes T-fan type chevrons, uniform chevrons on the core nozzle, and no additional pylon of the type that created a strong acoustic effect at lower bypass ratios. The T-fan chevrons are oriented azimuthally away from the ground observer locations. This best overall nozzle compared to the baseline nozzle was assessed, at equal thrust, to produce sufficient installed noise reduction of the jet noise component to enable the N2A HWB to meet NASA s noise goal of 42 dB cumulative below Stage 4.

Temperature Oscillations in Loop Heat Pipes - A Revisit

NASA Technical Reports Server (NTRS)

Ku, Jentung

2018-01-01

Three types of temperature oscillation have been observed in the loop heat pipes. The first type is an ultra-high frequency temperature oscillation with a period on the order of seconds or less. This type of temperature oscillation is of little significance in spacecraft thermal control because the amplitude is in the noise level. The second type is a high frequency, low amplitude temperature oscillation with a period on the order of seconds to minutes and an amplitude on the order of one Kelvin. It is caused by the back-and-forth movement of the vapor front near the inlet or outlet of the condenser. The third type is a low frequency, high amplitude oscillation with a period on the order of hours and an amplitude on the order of tens of Kelvin. It is caused by the modulation of the net heat load into the evaporator by the attached large thermal mass which absorbs and releases energy alternately. Several papers on LHP temperature oscillation have been published. This paper presents a further study on the underlying physical processes during the LHP temperature oscillation, with an emphasis on the third type of temperature oscillation. Specifically, equations governing the thermal and hydraulic behaviors of LHP operation will be used to describe interactions among LHP components, heat source, and heat sink. The following sequence of events and their interrelationship will also be explored: 1) maxima and minima of reservoir and thermal mass temperatures; 2) the range of the vapor front movement inside the condenser; 3) rates of change of the reservoir and thermal mass temperatures; 4) the rate of heat absorption and heat release by the thermal mass and the rate of vapor front movement; and 5) inflection points of the reservoir and thermal mass temperatures.

Investigation on a thermal-coupled two-stage Stirling-type pulse tube cryocooler

NASA Astrophysics Data System (ADS)

Yang, Luwei

2008-11-01

Multi-stage Stirling-type pulse tube cryocoolers with high frequency (30-60 Hz) are one important direction in recent years. A two-stage Stirling-type pulse tube cryocooler with thermally coupled stages has been designed and established two years ago and some results have been published. In order to study the effect of first stage precooling temperature, related characteristics on performance are experimentally investigated. It shows that at high input power, when the precooling temperature is lower than 110 K, its effect on second stage temperature is quite small. There is also the evident effect of precooling temperature on pulse tube temperature distribution; this is for the first time that author notice the phenomenon. The mean working pressure is investigated and the 12.8 K lowest temperature with 500 W input power and 1.22 MPa average pressure have been gained, this is the lowest reported temperature for high frequency two-stage PTCS. Simulation has reflected upper mentioned typical features in experiments.

Fabrication of piezoelectric ceramic micro-actuator and its reliability for hard disk drives.

PubMed

Jing, Yang; Luo, Jianbin; Yang, Wenyan; Ju, Guoxian

2004-11-01

A new U-type micro-actuator for precisely positioning a magnetic head in high-density hard disk drives was proposed and developed. The micro-actuator is composed of a U-type stainless steel substrate and two piezoelectric ceramic elements. Using a high-d31 piezoelectric coefficient PMN-PZT ceramic plate and adopting reactive ion etching process fabricate the piezoelectric elements. Reliability against temperature was investigated to ensure the practical application to the drive products. The U-type substrate attached to each side via piezoelectric elements also was simulated by the finite-element method and practically measured by a laser Doppler vibrometer in order to testify the driving mechanics of it. The micro-actuator coupled with two piezoelectric elements featured large displacement of 0.875 microm and high-resonance frequency over 22 kHz. The novel piezoelectric micro-actuators then possess a useful compromise performance to displacement, resonance frequency, and generative force. The results reveal that the new design concept provides a valuable alternative for multilayer piezoelectric micro-actuators.

Low Frequency Error Analysis and Calibration for High-Resolution Optical Satellite's Uncontrolled Geometric Positioning

NASA Astrophysics Data System (ADS)

Wang, Mi; Fang, Chengcheng; Yang, Bo; Cheng, Yufeng

2016-06-01

The low frequency error is a key factor which has affected uncontrolled geometry processing accuracy of the high-resolution optical image. To guarantee the geometric quality of imagery, this paper presents an on-orbit calibration method for the low frequency error based on geometric calibration field. Firstly, we introduce the overall flow of low frequency error on-orbit analysis and calibration, which includes optical axis angle variation detection of star sensor, relative calibration among star sensors, multi-star sensor information fusion, low frequency error model construction and verification. Secondly, we use optical axis angle change detection method to analyze the law of low frequency error variation. Thirdly, we respectively use the method of relative calibration and information fusion among star sensors to realize the datum unity and high precision attitude output. Finally, we realize the low frequency error model construction and optimal estimation of model parameters based on DEM/DOM of geometric calibration field. To evaluate the performance of the proposed calibration method, a certain type satellite's real data is used. Test results demonstrate that the calibration model in this paper can well describe the law of the low frequency error variation. The uncontrolled geometric positioning accuracy of the high-resolution optical image in the WGS-84 Coordinate Systems is obviously improved after the step-wise calibration.

Clinical and genetic characteristics of GAD-antibody positive patients initially diagnosed as having type 2 diabetes.

PubMed

Hamaguchi, Kazuyuki; Kimura, Akinori; Kusuda, Yoichiro; Yamashita, Tsutomu; Yasunami, Michio; Takahasi, Megumi; Abe, Nobuyuki; Yoshimatsu, Hironobu

2004-11-01

The present study was conducted to clarify the clinical and genetic characteristics of the diabetic patients who have antibodies to glutamic acid decarboxylase (GADab) but are diagnosed initially as type 2 diabetes because of the slow progression. Fifty-five GADab+ patients and 137 GADab- patients were recruited. The GADab+ patients were divided into two subgroups according to their antibody titers. The high-titer subgroup (Ab > or = 20 U/ml) had lower urinary C-peptide concentrations, and was assigned insulin therapy more often than the GADab- patients. In contrast to the high-titer subgroup, clinical parameters in the low-titer subgroup were similar to the GADab- diabetic patients. The urinary C-peptide levels correlated negatively with the GADab titer in the GADab+ patients. Analysis of type 1 diabetes-susceptible HLA alleles revealed high frequencies of the B54 and DRB1*0405 allele, but not the B61 and DRB1*0901 alleles, in the high-titer subgroup, whereas the frequency of the protective DRB1*1502 allele was decreased. The GADab+ patients with the B54 allele had higher GADab titers and lower urinary C-peptide excretion than patients without this allele. These data indicated that patients with a high-GADab titer share the autoimmune background characteristic of type 1 diabetes.

Association of genetic variants of the incretin-related genes with quantitative traits and occurrence of type 2 diabetes in Japanese.

PubMed

Enya, Mayumi; Horikawa, Yukio; Iizuka, Katsumi; Takeda, Jun

2014-01-01

None of the high frequency variants of the incretin-related genes has been found by genome-wide association study (GWAS) for association with occurrence of type 2 diabetes in Japanese. However, low frequency and rare and/or high frequency variants affecting glucose metabolic traits remain to be investigated. We screened all exons of the incretin-related genes ( GCG , GLP1R , DPP4 , PCSK1 , GIP , and GIPR ) in 96 patients with type 2 diabetes and investigated for association of genetic variants of these genes with quantitative metabolic traits upon test meal with 38 young healthy volunteers and with the occurrence of type 2 diabetes in Japanese subjects comprising 1303 patients with type 2 diabetes and 1014 controls. Two mutations of GIPR , p.Thr3Alafsx21 and Arg183Gln, were found only in patients with type 2 diabetes, and both of them were treated with insulin. Of ten tagSNPs, we found that risk allele C of SNP393 (rs6235) of PCSK1 was nominally associated with higher fasting insulin and HOMA-R ( P  = 0.034 and P  = 0.030), but not with proinsulin level, incretin level or BMI. The variant showed significant association with occurrence of type 2 diabetes after adjustment for age, sex, and BMI ( P  = 0.0043). Rare variants of GIPR may contribute to the development of type 2 diabetes, possibly through insulin secretory defects. Furthermore, the genetic variant of PCSK1 might influence glucose homeostasis by altered insulin resistance independently of BMI, incretin level or proinsulin conversion, and may be associated with the occurrence of type 2 diabetes in Japanese.

The MACHO Project Large Magellanic Cloud Variable-Star Inventory. IX. Frequency Analysis of the First-Overtone RR Lyrae Stars and the Indication for Nonradial Pulsations

NASA Astrophysics Data System (ADS)

Alcock, C.; Allsman, R.; Alves, D. R.; Axelrod, T.; Becker, A.; Bennett, D.; Clement, C.; Cook, K. H.; Drake, A.; Freeman, K.; Geha, M.; Griest, K.; Kovács, G.; Kurtz, D. W.; Lehner, M.; Marshall, S.; Minniti, D.; Nelson, C.; Peterson, B.; Popowski, P.; Pratt, M.; Quinn, P.; Rodgers, A.; Rowe, J.; Stubbs, C.; Sutherland, W.; Tomaney, A.; Vandehei, T.; Welch, D. L.

2000-10-01

More than 1300 variables classified provisionally as first-overtone RR Lyrae pulsators in the MACHO variable-star database of the Large Magellanic Cloud (LMC) have been subjected to standard frequency analysis. Based on the remnant power in the prewhitened spectra, we found 70% of the total population to be monoperiodic. The remaining 30% (411 stars) are classified as one of nine types according to their frequency spectra. Several types of RR Lyrae pulsational behavior are clearly identified here for the first time. Together with the earlier discovered double-mode (fundamental and first-overtone) variables, this study increased the number of known double-mode stars in the LMC to 181. During the total 6.5 yr time span of the data, 10% of the stars showed strong period changes. The size, and in general also the patterns of the period changes, exclude a simple evolutionary explanation. We also discovered two additional types of multifrequency pulsators with low occurrence rates of 2% for each. In the first type, there remains one closely spaced component after prewhitening by the main pulsation frequency. In the second type, the number of remnant components is two; they are also closely spaced, and are symmetric in their frequency spacing relative to the central component. This latter type of variables are associated with their relatives among the fundamental pulsators, known as Blazhko variables. Their high frequency (~20%) among the fundamental-mode variables versus the low occurrence rate of their first-overtone counterparts makes it more difficult to explain the Blazhko phenomenon by any theory depending mainly on the role of aspect angle or magnetic field. None of the current theoretical models are able to explain the observed close frequency components without invoking nonradial pulsation components in these stars.

Differentiation of the intracellular structure of slow- versus fast-twitch muscle fibers through evaluation of the dielectric properties of tissue

PubMed Central

Sanchez, B; Li, J; Bragos, R; Rutkove, S B

2014-01-01

Slow-twitch (type 1) skeletal muscle fibers have markedly greater mitochondrial content than fast-twitch (type 2) fibers. Accordingly, we sought to determine whether the dielectric properties of these two fiber types differed, consistent with their distinct intracellular morphologies. The longitudinal and transverse dielectric spectrum of the ex vivo rat soleus (a predominantly type 1 muscle) and the superficial layers of rat gastrocnemius (predominantly type 2) (n = 15) were measured in the 1 kHz–10 MHz frequency range and modeled to a resistivity Cole–Cole function. Major differences were especially apparent in the dielectric spectrum in the 1 to 10 MHz range. Specifically, the gastrocnemius demonstrated a well-defined, higher center frequency than the soleus muscle, whereas the soleus muscle showed a greater difference in the modeled zero and infinite resistivities than the gastrocnemius. These findings are consistent with the fact that soleus tissue has larger and more numerous mitochondria than gastrocnemius. Evaluation of tissue at high frequency could provide a novel approach for assessing intracellular structure in health and disease. PMID:24743385

Room-temperature multiferroic and magnetocapacitance effects in M-type hexaferrite BaFe{sub 10.2}Sc{sub 1.8}O{sub 19}

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

Tang, Rujun, E-mail: tangrj@suda.edu.cn, E-mail: yanghao@nuaa.edu.cn; Zhou, Hao; You, Wenlong

2016-08-22

The room-temperature multiferroic and magnetocapacitance (MC) effects of polycrystalline M-type hexaferrite BaFe{sub 10.2}Sc{sub 1.8}O{sub 19} have been investigated. The results show that the magnetic moments of insulating BaFe{sub 10.2}Sc{sub 1.8}O{sub 19} can be manipulated by the electric field at room temperature, indicating the existence of magnetoelectric coupling. Moreover, large MC effects are also observed around the room temperature. A frequency dependence analysis shows that the Maxwell-Wagner type magnetoresistance effect is the dominant mechanism for MC effects at low frequencies. Both the magnetoelectric-type and non-magnetoelectric-type spin-phonon couplings contribute to the MC effects at high frequencies with the former being the dominantmore » mechanism. The above results show that the hexaferrite BaFe{sub 10.2}Sc{sub 1.8}O{sub 19} is a room-temperature multiferroic material that can be potentially used in magnetoelectric devices.« less

Differentiation of the intracellular structure of slow- versus fast-twitch muscle fibers through evaluation of the dielectric properties of tissue

NASA Astrophysics Data System (ADS)

Sanchez, B.; Li, J.; Bragos, R.; Rutkove, S. B.

2014-05-01

Slow-twitch (type 1) skeletal muscle fibers have markedly greater mitochondrial content than fast-twitch (type 2) fibers. Accordingly, we sought to determine whether the dielectric properties of these two fiber types differed, consistent with their distinct intracellular morphologies. The longitudinal and transverse dielectric spectrum of the ex vivo rat soleus (a predominantly type 1 muscle) and the superficial layers of rat gastrocnemius (predominantly type 2) (n = 15) were measured in the 1 kHz-10 MHz frequency range and modeled to a resistivity Cole-Cole function. Major differences were especially apparent in the dielectric spectrum in the 1 to 10 MHz range. Specifically, the gastrocnemius demonstrated a well-defined, higher center frequency than the soleus muscle, whereas the soleus muscle showed a greater difference in the modeled zero and infinite resistivities than the gastrocnemius. These findings are consistent with the fact that soleus tissue has larger and more numerous mitochondria than gastrocnemius. Evaluation of tissue at high frequency could provide a novel approach for assessing intracellular structure in health and disease.

Solar Drift-Pair Bursts

NASA Astrophysics Data System (ADS)

Stanislavsky, A.; Volvach, Ya.; Konovalenko, A.; Koval, A.

2017-08-01

In this paper a new sight on the study of solar bursts historically called drift pairs (DPs) is presented. Having a simple morphology on dynamic spectra of radio records (two short components separated in time, and often they are very similar) and discovered at the dawn of radio astronomy, their features remain unexplained totally up to now. Generally, the DPs are observed during the solar storms of type III bursts, but not every storm of type III bursts is linked with DPs. Detected by ground-based instruments at decameter and meter wavelengths, the DP bursts are limited in frequency bandwidth. They can drift from high frequencies to low ones and vice versa. Their frequency drift rate may be both lower and higher than typical rates of type III bursts at the same frequency range. The development of low-frequency radio telescopes and data processing provide additional possibilities in the research. In this context the fresh analysis of DPs, made from recent observations in the summer campaign of 2015, are just considered. Their study was implemented by updated tools of the UTR-2 radio telescope at 9-33 MHz. During 10-12 July of 2015, DPs forming the longest patterns on dynamic spectra are about 7% of the total number of recorded DPs. Their marvelous resemblance in frequency drift rates with the solar S-bursts is discussed.

Deriving Animal Behaviour from High-Frequency GPS: Tracking Cows in Open and Forested Habitat

PubMed Central

de Weerd, Nelleke; van Langevelde, Frank; van Oeveren, Herman; Nolet, Bart A.; Kölzsch, Andrea; Prins, Herbert H. T.; de Boer, W. Fred

2015-01-01

The increasing spatiotemporal accuracy of Global Navigation Satellite Systems (GNSS) tracking systems opens the possibility to infer animal behaviour from tracking data. We studied the relationship between high-frequency GNSS data and behaviour, aimed at developing an easily interpretable classification method to infer behaviour from location data. Behavioural observations were carried out during tracking of cows (Bos Taurus) fitted with high-frequency GPS (Global Positioning System) receivers. Data were obtained in an open field and forested area, and movement metrics were calculated for 1 min, 12 s and 2 s intervals. We observed four behaviour types (Foraging, Lying, Standing and Walking). We subsequently used Classification and Regression Trees to classify the simultaneously obtained GPS data as these behaviour types, based on distances and turning angles between fixes. GPS data with a 1 min interval from the open field was classified correctly for more than 70% of the samples. Data from the 12 s and 2 s interval could not be classified successfully, emphasizing that the interval should be long enough for the behaviour to be defined by its characteristic movement metrics. Data obtained in the forested area were classified with a lower accuracy (57%) than the data from the open field, due to a larger positional error of GPS locations and differences in behavioural performance influenced by the habitat type. This demonstrates the importance of understanding the relationship between behaviour and movement metrics, derived from GNSS fixes at different frequencies and in different habitats, in order to successfully infer behaviour. When spatially accurate location data can be obtained, behaviour can be inferred from high-frequency GNSS fixes by calculating simple movement metrics and using easily interpretable decision trees. This allows for the combined study of animal behaviour and habitat use based on location data, and might make it possible to detect deviations in behaviour at the individual level. PMID:26107643

Deriving Animal Behaviour from High-Frequency GPS: Tracking Cows in Open and Forested Habitat.

PubMed

de Weerd, Nelleke; van Langevelde, Frank; van Oeveren, Herman; Nolet, Bart A; Kölzsch, Andrea; Prins, Herbert H T; de Boer, W Fred

2015-01-01

The increasing spatiotemporal accuracy of Global Navigation Satellite Systems (GNSS) tracking systems opens the possibility to infer animal behaviour from tracking data. We studied the relationship between high-frequency GNSS data and behaviour, aimed at developing an easily interpretable classification method to infer behaviour from location data. Behavioural observations were carried out during tracking of cows (Bos Taurus) fitted with high-frequency GPS (Global Positioning System) receivers. Data were obtained in an open field and forested area, and movement metrics were calculated for 1 min, 12 s and 2 s intervals. We observed four behaviour types (Foraging, Lying, Standing and Walking). We subsequently used Classification and Regression Trees to classify the simultaneously obtained GPS data as these behaviour types, based on distances and turning angles between fixes. GPS data with a 1 min interval from the open field was classified correctly for more than 70% of the samples. Data from the 12 s and 2 s interval could not be classified successfully, emphasizing that the interval should be long enough for the behaviour to be defined by its characteristic movement metrics. Data obtained in the forested area were classified with a lower accuracy (57%) than the data from the open field, due to a larger positional error of GPS locations and differences in behavioural performance influenced by the habitat type. This demonstrates the importance of understanding the relationship between behaviour and movement metrics, derived from GNSS fixes at different frequencies and in different habitats, in order to successfully infer behaviour. When spatially accurate location data can be obtained, behaviour can be inferred from high-frequency GNSS fixes by calculating simple movement metrics and using easily interpretable decision trees. This allows for the combined study of animal behaviour and habitat use based on location data, and might make it possible to detect deviations in behaviour at the individual level.

Spectropolarimetric Observations of Solar Noise Storms at Low Frequencies

NASA Astrophysics Data System (ADS)

Mugundhan, V.; Ramesh, R.; Kathiravan, C.; Gireesh, G. V. S.; Hegde, Aathira

2018-03-01

A new high-resolution radio spectropolarimeter instrument operating in the frequency range of 15 - 85 MHz has recently been commissioned at the Radio Astronomy Field Station of the Indian Institute of Astrophysics at Gauribidanur, 100 km north of Bangalore, India. We describe the design and construction of this instrument. We present observations of a solar radio noise storm associated with Active Region (AR) 12567 in the frequency range of {≈} 15 - 85 MHz during 18 and 19 July 2016, observed using this instrument in the meridian-transit mode. This is the first report that we are aware of in which both the burst and continuum properties are derived simultaneously. Spectral indices and degree of polarization of both the continuum radiation and bursts are estimated. It is found that i) Type I storm bursts have a spectral index of {≈} {+}3.5, ii) the spectral index of the background continuum is ≈+2.9, iii) the transition frequency between Type I and Type III storms occurs at ≈55 MHz, iv) Type III bursts have an average spectral index of ≈-2.7, v) the spectral index of the Type III continuum is ≈-1.6, and vi) the degree of circular polarization of all Type I (Type III) bursts is ≈90% (30%). The results obtained here indicate that the continuum emission is due to bursts occurring in rapid succession. We find that the derived parameters for Type I bursts are consistent with suprathermal electron acceleration theory and those of Type III favor fundamental plasma emission.

Phase correlation of laser waves with arbitrary frequency spacing.

PubMed

Huss, A F; Lammegger, R; Neureiter, C; Korsunsky, E A; Windholz, L

2004-11-26

The theoretically predicted correlation of laser phase fluctuations in Lambda-type interaction schemes is experimentally demonstrated. We show that the mechanism of correlation in a Lambda scheme is restricted to high-frequency noise components, whereas in a double-Lambda scheme, due to the laser phase locking in a closed-loop interaction, it extends to all noise frequencies. In this case the correlation is weakly sensitive to coherence losses. Thus the double-Lambda scheme can be used to correlate electromagnetic fields with carrier frequency differences beyond the GHz regime.

Response properties of single units in the dorsal nucleus of the lateral lemniscus of decerebrate cats.

PubMed

Davis, Kevin A; Lomakin, Oleg; Pesavento, Michael J

2007-09-01

The dorsal nucleus of the lateral lemniscus (DNLL) receives afferent inputs from many brain stem nuclei and, in turn, is a major source of inhibitory inputs to the inferior colliculus (IC). The goal of this study was to characterize the monaural and binaural response properties of neurons in the DNLL of unanesthetized decerebrate cat. Monaural responses were classified according to the patterns of excitation and inhibition observed in contralateral and ipsilateral frequency response maps. Binaural classification was based on unit sensitivity to interaural level differences. The results show that units in the DNLL can be grouped into three distinct types. Type v units produce contralateral response maps that show a wide V-shaped excitatory area and no inhibition. These units receive ipsilateral excitation and exhibit binaural facilitation. The contralateral maps of type i units show a more restricted I-shaped region of excitation that is flanked by inhibition. Type o maps display an O-shaped island of excitation at low stimulus levels that is bounded by inhibition at higher levels. Both type i and type o units receive ipsilateral inhibition and exhibit binaural inhibition. Units that produce type v maps have a low best frequency (BF), whereas type i and type o units have high BFs. Type v and type i units give monotonic rate-level responses for both BF tones and broadband noise. Type o units are inhibited by tones at high levels, but are excited by high-level noise. These results show that the DNLL can exert strong, differential effects in the IC.

Study on efficiency of different topologies of magnetic coupled resonant wireless charging system

NASA Astrophysics Data System (ADS)

Cui, S.; Liu, Z. Z.; Hou, Y. J.; Zeng, H.; Yue, Z. K.; Liang, L. H.

2017-11-01

This paper analyses the relationship between the output power, the transmission efficiency and the frequency, load and coupling coefficient of the four kinds of magnetic coupled resonant wireless charging system topologies. Based on mutual inductance principle, four kinds of circuit models are established, and the expressions of output power and transmission efficiency of different structures are calculated. The difference between the two power characteristics and efficiency characteristics is compared by simulating the SS (series-series) and SP (series-parallel) type wireless charging systems. With the same parameters of circuit components, the SS structure is usually suitable for small load resistance. The SP structure can be applied to large load resistors, when the transmission efficiency of the system is required to keep high. If the operating frequency deviates from the system resonance frequency, the SS type system has higher transmission efficiency than the SP type system.

Fabrication and characterization of physically defined quantum dots on a boron-doped silicon-on-insulator substrate

NASA Astrophysics Data System (ADS)

Mizoguchi, Seiya; Shimatani, Naoki; Kobayashi, Mizuki; Makino, Takaomi; Yamaoka, Yu; Kodera, Tetsuo

2018-04-01

We study hole transport properties in physically defined p-type silicon quantum dots (QDs) on a heavily doped silicon-on-insulator (SOI) substrate. We observe Coulomb diamonds using single QDs and estimate the charging energy as ∼1.6 meV. We obtain the charge stability diagram of double QDs using single QDs as a charge sensor. This is the first demonstration of charge sensing in p-type heavily doped silicon QDs. For future time-resolved measurements, we apply radio-frequency reflectometry using impedance matching of LC circuits to the device. We observe the resonance and estimate the capacitance as ∼0.12 pF from the resonant frequency. This value is smaller than that of the devices with top gates on nondoped SOI substrate. This indicates that high-frequency signals can be applied efficiently to p-type silicon QDs without top gates.

Ytterbium-doped fibre laser Q-switched by a cantilever-type micro-mirror.

PubMed

Fabert, Marc; Desfarges-Berthelemot, Agnès; Kermène, Vincent; Crunteanu, Aurelian; Bouyge, David; Blondy, Pierre

2008-12-22

We present an Ytterbium fibre laser operating in the Q-switch regime by using a Micro- Opto- Electro- Mechanical System (MOEMS) of novel design. The cantilever-type micro-mirror is designed to generate short laser pulses with duration between 20 ns and 100 ns at repetition rates ranging from a few kilohertz up to 800 kHz. The bent profile of this new type of MOEMS ensures a high modulation rate of the laser cavity losses while keeping a high actuating frequency.

Cyclotron Phase-Coherent Ion Spatial Dispersion in a Non-Quadratic Trapping Potential is Responsible for FT-ICR MS at the Cyclotron Frequency

NASA Astrophysics Data System (ADS)

Nagornov, Konstantin O.; Kozhinov, Anton N.; Tsybin, Yury O.

2018-01-01

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) at the cyclotron frequency instead of the reduced cyclotron frequency has been experimentally demonstrated using narrow aperture detection electrode (NADEL) ICR cells. Here, based on the results of SIMION simulations, we provide the initial mechanistic insights into the cyclotron frequency regime generation in FT-ICR MS. The reason for cyclotron frequency regime is found to be a new type of a collective motion of ions with a certain dispersion in the initial characteristics, such as pre-excitation ion velocities, in a highly non-quadratic trapping potential as realized in NADEL ICR cells. During ion detection, ions of the same m/z move in phase for cyclotron ion motion but out of phase for magnetron (drift) ion motion destroying signals at the fundamental and high order harmonics that comprise reduced cyclotron frequency components. After an initial magnetron motion period, ion clouds distribute into a novel type of structures - ion slabs, elliptical cylinders, or star-like structures. These structures rotate at the Larmor (half-cyclotron) frequency on a plane orthogonal to the magnetic field, inducing signals at the true cyclotron frequency on each of the narrow aperture detection electrodes. To eliminate the reduced cyclotron frequency peak upon dipolar ion detection, a number of slabs or elliptical cylinders organizing a star-like configuration are formed. In a NADEL ICR cell with quadrupolar ion detection, a single slab or an elliptical cylinder is sufficient to minimize the intensity of the reduced cyclotron frequency components, particularly the second harmonic. [Figure not available: see fulltext.

Development of multi-frequency ESR system for high-pressure measurements up to 2.5 GPa.

PubMed

Sakurai, T; Fujimoto, K; Matsui, R; Kawasaki, K; Okubo, S; Ohta, H; Matsubayashi, K; Uwatoko, Y; Tanaka, H

2015-10-01

A new piston-cylinder pressure cell for electron spin resonance (ESR) has been developed. The pressure cell consists of a double-layer hybrid-type cylinder with internal components made of the ZrO2-based ceramics. It can generate a pressure of 2 GPa repeatedly and reaches a maximum pressure of around 2.5 GPa. A high-pressure ESR system using a cryogen-free superconducting magnet up 10T has also been developed for this hybrid-type pressure cell. The frequency region is from 50 GHz to 400 GHz. This is the first time a pressure above 2 GPa has been achieved in multi-frequency ESR system using a piston-cylinder pressure cell. We demonstrate its potential by showing the results of the high-pressure ESR of the S=1 system with the single ion anisotropy NiSnCl6·6H2O and the S=1/2 quantum spin system CsCuCl3. We performed ESR measurements of these systems above 2 GPa successfully. Copyright © 2015 Elsevier Inc. All rights reserved.

Micromachined PIN-PMN-PT crystal composite transducer for high-frequency intravascular ultrasound (IVUS) imaging.

PubMed

Li, Xiang; Ma, Teng; Tian, Jian; Han, Pengdi; Zhou, Qifa; Shung, K Kirk

2014-07-01

In this paper, we report the use of micromachined PbIn1/2Nb1/2O3-PbMg1/3Nb2/3O3-PbTiO 3 (PIN-PMNPT) single crystal 1-3 composite material for intravascular ultrasound (IVUS) imaging application. The effective electromechanical coupling coefficient kt(eff) of the composite was measured to be 0.75 to 0.78. Acoustic impedance was estimated to be 20 MRayl. Based on the composite, needle-type and flexible-type IVUS transducers were fabricated. The composite transducer achieved an 86% bandwidth at the center frequency of 41 MHz, which resulted in a 43 μm axial resolution. Ex vivo IVUS imaging was conducted to demonstrate the improvement of axial resolution. The composite transducer was capable of identifying the three layers of a cadaver coronary artery specimen with high resolution. The PIN-PMN-PT-based composite has superior piezoelectric properties comparable to PMN-PT-based composite and its thermal stability is higher than PMN-PT. PIN-PMN-PT crystal can be an alternative approach for fabricating high-frequency composite, instead of using PMN-PT.

Partial Discharge Spectral Characterization in HF, VHF and UHF Bands Using Particle Swarm Optimization.

PubMed

Robles, Guillermo; Fresno, José Manuel; Martínez-Tarifa, Juan Manuel; Ardila-Rey, Jorge Alfredo; Parrado-Hernández, Emilio

2018-03-01

The measurement of partial discharge (PD) signals in the radio frequency (RF) range has gained popularity among utilities and specialized monitoring companies in recent years. Unfortunately, in most of the occasions the data are hidden by noise and coupled interferences that hinder their interpretation and renders them useless especially in acquisition systems in the ultra high frequency (UHF) band where the signals of interest are weak. This paper is focused on a method that uses a selective spectral signal characterization to feature each signal, type of partial discharge or interferences/noise, with the power contained in the most representative frequency bands. The technique can be considered as a dimensionality reduction problem where all the energy information contained in the frequency components is condensed in a reduced number of UHF or high frequency (HF) and very high frequency (VHF) bands. In general, dimensionality reduction methods make the interpretation of results a difficult task because the inherent physical nature of the signal is lost in the process. The proposed selective spectral characterization is a preprocessing tool that facilitates further main processing. The starting point is a clustering of signals that could form the core of a PD monitoring system. Therefore, the dimensionality reduction technique should discover the best frequency bands to enhance the affinity between signals in the same cluster and the differences between signals in different clusters. This is done maximizing the minimum Mahalanobis distance between clusters using particle swarm optimization (PSO). The tool is tested with three sets of experimental signals to demonstrate its capabilities in separating noise and PDs with low signal-to-noise ratio and separating different types of partial discharges measured in the UHF and HF/VHF bands.

Automated classification of mouse pup isolation syllables: from cluster analysis to an Excel-based "mouse pup syllable classification calculator".

PubMed

Grimsley, Jasmine M S; Gadziola, Marie A; Wenstrup, Jeffrey J

2012-01-01

Mouse pups vocalize at high rates when they are cold or isolated from the nest. The proportions of each syllable type produced carry information about disease state and are being used as behavioral markers for the internal state of animals. Manual classifications of these vocalizations identified 10 syllable types based on their spectro-temporal features. However, manual classification of mouse syllables is time consuming and vulnerable to experimenter bias. This study uses an automated cluster analysis to identify acoustically distinct syllable types produced by CBA/CaJ mouse pups, and then compares the results to prior manual classification methods. The cluster analysis identified two syllable types, based on their frequency bands, that have continuous frequency-time structure, and two syllable types featuring abrupt frequency transitions. Although cluster analysis computed fewer syllable types than manual classification, the clusters represented well the probability distributions of the acoustic features within syllables. These probability distributions indicate that some of the manually classified syllable types are not statistically distinct. The characteristics of the four classified clusters were used to generate a Microsoft Excel-based mouse syllable classifier that rapidly categorizes syllables, with over a 90% match, into the syllable types determined by cluster analysis.

Dynamics of a gain-switched distributed feedback ridge waveguide laser in nanoseconds time scale under very high current injection conditions.

PubMed

Klehr, A; Wenzel, H; Brox, O; Schwertfeger, S; Staske, R; Erbert, G

2013-02-11

We present detailed experimental investigations of the temporal, spectral and spatial behavior of a gain-switched distributed feedback (DFB) laser emitting at a wavelength of 1064 nm. Gain-switching is achieved by injecting nearly rectangular shaped current pulses having a length of 50 ns and a very high amplitude up to 2.5 A. The repetition frequency is 200 kHz. The laser has a ridge waveguide (RW) for lateral waveguiding with a ridge width of 3 µm and a cavity length of 1.5 mm. Time resolved investigations show, depending on the amplitude of the current pulses, that the optical power exhibits different types of oscillatory behavior during the pulses, accompanied by changes in the lateral near field intensity profiles and optical spectra. Three different types of instabilities can be distinguished: mode beating with frequencies between 25 GHz and 30 GHz, switching between different lateral intensity profiles with a frequency of 0.4 GHz and self-sustained oscillations with a frequency of 4 GHz. The investigations are of great relevance for the utilization of gain-switched DFB-RW lasers as seed lasers for fiber laser systems and in other applications, which require a high optical power.

High-frequency applications of high-temperature superconductor thin films

NASA Astrophysics Data System (ADS)

Klein, N.

2002-10-01

High-temperature superconducting thin films offer unique properties which can be utilized for a variety of high-frequency device applications in many areas related to the strongly progressing market of information technology. One important property is an exceptionally low level of microwave absorption at temperatures attainable with low power cryocoolers. This unique property has initiated the development of various novel type of microwave devices and commercialized subsystems with special emphasis on application in advanced microwave communication systems. The second important achievement related to efforts in oxide thin and multilayer technology was the reproducible fabrication of low-noise Josephson junctions in high-temperature superconducting thin films. As a consequence of this achievement, several novel nonlinear high-frequency devices, most of them exploiting the unique features of the ac Josephson effect, have been developed and found to exhibit challenging properties to be utilized in basic metrology and Terahertz technology. On the longer timescale, the achievements in integrated high-temperature superconductor circuit technology may offer a strong potential for the development of digital devices with possible clock frequencies in the range of 100 GHz.

An Investigation of the Dynamic Response of a Seismically Stable Platform

DTIC Science & Technology

1982-08-01

PAD. The controls on the -9system are of two types. A low frequency tilt control, with a 10 arc second sensitivity, 2-axis tiltmeter as sensor ...Inertial Sensors Structural Analysis Holloman AFB, NiM. Support to this effort includes structural analyses toward active servo frequency band. This report...controlled to maintain a null position of a sensitive height sensor . The 6-degree-of- freedom high frequency controls are based on seismometers as sensors

Frequency and voltage dependent electrical responses of poly(triarylamine) thin film-based organic Schottky diode

NASA Astrophysics Data System (ADS)

Anuar Mohamad, Khairul; Tak Hoh, Hang; Alias, Afishah; Ghosh, Bablu Kumar; Fukuda, Hisashi

2017-11-01

A metal-organic-metal (MOM) type Schottky diode based on poly (triarylamine) (PTAA) thin films has been fabricated by using the spin coating method. Investigation of the frequency dependent conductance-voltage (G-V-f) and capacitance-voltage (C-V-f) characteristics of the ITO/PTAA/Al MOM type diode were carried out in the frequency range from 12 Hz to 100 kHz using an LCR meter at room temperature. The frequency and bias voltage dependent electrical response were determined by admittance-based measured method in terms of an equivalent circuit model of the parallel combination of resistance and capacitance (RC circuit). Investigation revealed that the conductance is frequency and a bias voltage dependent in which conductance continuous increase as the increasing frequency, respectively. Meanwhile, the capacitance is dependent on frequency up to a certain value of frequency (100 Hz) but decreases at high frequency (1 - 10 kHz). The interface state density in the Schottky diode was determined from G-V and C-V characteristics. The interface state density has values almost constant of 2.8 x 1012 eV-1cm-2 with slightly decrease by increasing frequencies. Consequently, both series resistance and interface trap density were found to decrease with increasing frequency. The frequency dependence of the electrical responses is attributed the distribution density of interface states that could follow the alternating current (AC) signal.

Studies at high frequencies of the 30 Doradus and RCW 57 regions.

NASA Astrophysics Data System (ADS)

Sabalisck, N. S. P.; Abraham, Z.

1990-11-01

The authors present maps of the 30 Dor region at 22 GHz and of the RCW 57 region at 43 GHz. The data are compared with maps at lower frequencies and similar resolutions. In the 30 Dor region 3 supernova remnants of plerionic type were detected: N 1578, MC 78 and MC 89.

Electronic stethoscope with frequency shaping and infrasonic recording capabilities.

PubMed

Gordon, E S; Lagerwerff, J M

1976-03-01

A small electronic stethoscope with variable frequency response characteristics has been developed for aerospace and research applications. The system includes a specially designed piezoelectric pickup and amplifier with an overall frequency response from 0.7 to 5,000 HZ (-3 dB points) and selective bass and treble boost or cut of up to 15 dB. A steep slope, high pass filter can be switched in for ordinary clinical auscultation without overload distortion from strong infrasonic signal inputs. A commercial stethoscope-type headset, selected for best overall response, is used which can adequately handle up to 100 mW of audio power delivered from the amplifier. The active components of the amplifier consist of only four opamp-type integrated circuits.

Ultra-broadband near-field antenna for terahertz plasmonic applications

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

Polischuk, O. V., E-mail: polischuk.sfire@mail.ru; Popov, V. V., E-mail: popov-slava@yahoo.co.uk; Knap, W.

A new type of ultra-broadband near-field antenna for terahertz frequencies is proposed. This antenna is a short-period planar metal array. It is theoretically shown that irradiation of the short-period array antenna by a plane homogeneous terahertz waves excite a highly inhomogeneous near electric field near the metal array. In this case, the amplitude of the excited inhomogeneous near electric field is almost independent of frequency in the entire terahertz frequency range. The excitation of plasma oscillations in a two-dimensional electron system using the antenna under study is numerically simulated in the resonant and non-resonant plasmonic response modes. This type ofmore » antenna can be used for developing ultra-broadband plasmonic detectors of terahertz radiation.« less

Glacier microseismicity

USGS Publications Warehouse

West, Michael E.; Larsen, Christopher F.; Truffer, Martin; O'Neel, Shad; LeBlanc, Laura

2010-01-01

We present a framework for interpreting small glacier seismic events based on data collected near the center of Bering Glacier, Alaska, in spring 2007. We find extremely high microseismicity rates (as many as tens of events per minute) occurring largely within a few kilometers of the receivers. A high-frequency class of seismicity is distinguished by dominant frequencies of 20–35 Hz and impulsive arrivals. A low-frequency class has dominant frequencies of 6–15 Hz, emergent onsets, and longer, more monotonic codas. A bimodal distribution of 160,000 seismic events over two months demonstrates that the classes represent two distinct populations. This is further supported by the presence of hybrid waveforms that contain elements of both event types. The high-low-hybrid paradigm is well established in volcano seismology and is demonstrated by a comparison to earthquakes from Augustine Volcano. We build on these parallels to suggest that fluid-induced resonance is likely responsible for the low-frequency glacier events and that the hybrid glacier events may be caused by the rush of water into newly opening pathways.

High Frequency Plasma Generators for Ion Thrusters

NASA Technical Reports Server (NTRS)

Divergilio, W. F.; Goede, H.; Fosnight, V. V.

1981-01-01

The results of a one year program to experimentally adapt two new types of high frequency plasma generators to Argon ion thrusters and to analytically study a third high frequency source concept are presented. Conventional 30 cm two grid ion extraction was utilized or proposed for all three sources. The two plasma generating methods selected for experimental study were a radio frequency induction (RFI) source, operating at about 1 MHz, and an electron cyclotron heated (ECH) plasma source operating at about 5 GHz. Both sources utilize multi-linecusp permanent magnet configurations for plasma confinement. The plasma characteristics, plasma loading of the rf antenna, and the rf frequency dependence of source efficiency and antenna circuit efficiency are described for the RFI Multi-cusp source. In a series of tests of this source at Lewis Research Center, minimum discharge losses of 220+/-10 eV/ion were obtained with propellant utilization of .45 at a beam current of 3 amperes. Possible improvement modifications are discussed.

Draft evaluation of the frequency for gas sampling for the high burnup confirmatory data project

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

Stockman, Christine T.; Alsaed, Halim A.; Bryan, Charles R.

2015-03-26

This report fulfills the M3 milestone M3FT-15SN0802041, “Draft Evaluation of the Frequency for Gas Sampling for the High Burn-up Storage Demonstration Project” under Work Package FT-15SN080204, “ST Field Demonstration Support – SNL”. This report provides a technically based gas sampling frequency strategy for the High Burnup (HBU) Confirmatory Data Project. The evaluation of: 1) the types and magnitudes of gases that could be present in the project cask and, 2) the degradation mechanisms that could change gas compositions culminates in an adaptive gas sampling frequency strategy. This adaptive strategy is compared against the sampling frequency that has been developed basedmore » on operational considerations. Gas sampling will provide information on the presence of residual water (and byproducts associated with its reactions and decomposition) and breach of cladding, which could inform the decision of when to open the project cask.« less

Light weight polarized polypropylene foam for noise shielding

NASA Astrophysics Data System (ADS)

Zelfer, Travis J.; Warne, Derik S.; Korde, Umesh A.

2009-03-01

The high levels of noise generated during launch can destroy sensitive equipment on space craft. Passive damping systems, like acoustic blankets, work to reduce the high frequency noise but do little to the low frequency noise (<400 Hz). While wall mounted transducers can reduce the low frequency noise during a launch, they also can create areas of higher increased sound pressure in the payload fairings. Ferroelectret cellular polymer foams with high piezoelectric coupling constants are being used as new types of actuators and sensors. Further impedance control through the inverse piezoelectric effect will lead to a new "semi-active" approach that will reduce low frequency noise levels. Combining layers of conventional nonpiezoelectric foam and ferroelectret materials with a multiple loop feedback system will give a total damping effect that is adaptable over a wide band of low frequencies. This paper covers the manufacturing methods that were used to make polarized polypropylene foam, to test the foam for its polarized response and its noise shielding ability.

Square or sine: finding a waveform with high success rate of eliciting SSVEP.

PubMed

Teng, Fei; Chen, Yixin; Choong, Aik Min; Gustafson, Scott; Reichley, Christopher; Lawhead, Pamela; Waddell, Dwight

2011-01-01

Steady state visual evoked potential (SSVEP) is the brain's natural electrical potential response for visual stimuli at specific frequencies. Using a visual stimulus flashing at some given frequency will entrain the SSVEP at the same frequency, thereby allowing determination of the subject's visual focus. The faster an SSVEP is identified, the higher information transmission rate the system achieves. Thus, an effective stimulus, defined as one with high success rate of eliciting SSVEP and high signal-noise ratio, is desired. Also, researchers observed that harmonic frequencies often appear in the SSVEP at a reduced magnitude. Are the harmonics in the SSVEP elicited by the fundamental stimulating frequency or by the artifacts of the stimuli? In this paper, we compare the SSVEP responses of three periodic stimuli: square wave (with different duty cycles), triangle wave, and sine wave to find an effective stimulus. We also demonstrate the connection between the strength of the harmonics in SSVEP and the type of stimulus.

[Association of the cocaine and amphetamine-regulated transcript gene with type 2 diabetes mellitus].

PubMed

Fu, Mao; Cheng, Hua; Chen, Lihong; Wu, Bin; Cai, Mengyin; Xie, Ding; Fu, Zuzhi

2002-12-01

To investigate whether genetic variation in cocaine and amphetamine-regulated transcript (CART) gene might contribute to the genesis of type 2 diabetes. Screening for mutations in the entire coding region for the CART gene were performed with polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) in 180 normoglycemic control subjects and 221 patients with type 2 diabetes. (1) Adenine deletion was identified at position 1,457 nucleotide located at untranslation area of exon 3. In normal weight control, the frequencies of CART-A + and CART-A-alleles were 83.6% and 16.4% respectively. The frequencies of CART-A + A +, A + A-, A-A- genotype were 68.9%, 29.4% and 1.7% respectively. (2) In diabetic patients, the frequencies of CART-A + and A-alleles were 84.6% and 15.4% respectively; the frequencies of CART-A + A +, A + A-, A-A- genotype were 71.9%, 25.3% and 2.7% respectively. The frequency of A deletion of the CART gene in diabetic patients did not differ significantly from normoglycemic control subjects. (3) Diabetic patients with the A deletion had increased total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol. Polymorphism was found in the 3'-untranslated region (Delta A1457) of CART in Chinese. A deletion in CART is not associated with type 2 diabetes, but may contribute to dyslipidemia.

Large scale modulation of high frequency acoustic waves in periodic porous media.

PubMed

Boutin, Claude; Rallu, Antoine; Hans, Stephane

2012-12-01

This paper deals with the description of the modulation at large scale of high frequency acoustic waves in gas saturated periodic porous media. High frequencies mean local dynamics at the pore scale and therefore absence of scale separation in the usual sense of homogenization. However, although the pressure is spatially varying in the pores (according to periodic eigenmodes), the mode amplitude can present a large scale modulation, thereby introducing another type of scale separation to which the asymptotic multi-scale procedure applies. The approach is first presented on a periodic network of inter-connected Helmholtz resonators. The equations governing the modulations carried by periodic eigenmodes, at frequencies close to their eigenfrequency, are derived. The number of cells on which the carrying periodic mode is defined is therefore a parameter of the modeling. In a second part, the asymptotic approach is developed for periodic porous media saturated by a perfect gas. Using the "multicells" periodic condition, one obtains the family of equations governing the amplitude modulation at large scale of high frequency waves. The significant difference between modulations of simple and multiple mode are evidenced and discussed. The features of the modulation (anisotropy, width of frequency band) are also analyzed.

Sustainable limitation of high-frequency oscillations of elevator cabin

NASA Astrophysics Data System (ADS)

Kaytukov, Batraz

2017-10-01

In this paper, a problem of sustainable limitation of vertical high-frequency oscillations of elevator cabin in buildings with various number of storeys is considered. To solve this problem, dynamic model of the elevator movement was developed. In the course of analytical and experimental studies, the main cause for emergence of undesirable high-frequency oscillations of a cabin was defined. The amplification factor which is the function of λ and length of cable was determined. The λ parameter is variable, and length of the cable changes depending on length passed by the cabin and is an amplification factor argument. For sustainable limitation of oscillations, use of dynamic dumper of lever type is proposed. Adjustment of the dumper natural vibration frequency in such a way that it is equal to the excitation frequency allows limiting of oscillations of the cabin and the elevator machine to reasonable value irrespective to position of a moving cabin in the shaft. Using dependences and plots which were obtained in the course of scientific analysis and experimental studies, reasonability of dumper application for sustainable limitation of high-frequency influence of the elevator machine on the base and obtaining of solutions of inertial forces equilibration problem was proved.

Wide-band analog frequency modulation of optic signals using indirect techniques

NASA Technical Reports Server (NTRS)

Fitzmartin, D. J.; Balboni, E. J.; Gels, R. G.

1991-01-01

The wideband frequency modulation (FM) of an optical carrier by a radio frequency (RF) or microwave signal can be accomplished independent of laser type when indirect modulation is employed. Indirect modulators exploit the integral relation of phase to frequency so that phase modulators can be used to impress frequency modulation on an optical carrier. The use of integrated optics phase modulators, which are highly linear, enables the generation of optical wideband FM signals with very low intermodulation distortion. This modulator can be used as part of an optical wideband FM link for RF and microwave signals. Experimental results from the test of an indirect frequency modulator for an optical carrier are discussed.

Fatigue limit and Hysteresis Behavior of Type 304L Stainless Steel in Air and PWR Water, at 150°C and 300°C

NASA Astrophysics Data System (ADS)

Solomon, H. D.; Amzallag, C.; Vallee, A. J.; DeLair, R. E.

This is a study of the 107 cycle fatigue limit of Type 304L Stainless Steel, as measured in fully reversed (R=-1) load-controlled tests, at 150°C and 300°C, in air and PWR water. The staircase method was used to determine the fatigue limit. The tests run here utilized a cycle frequency of 1.818Hz and are compared to other tests from the literature that were run at 30Hz. The fatigue limit measured in the tests run at the high frequency was higher than that measured here. This is explained by measurements of the strain developed during cycling, using the different cycle frequencies. The tests run at the higher frequencies yielded lower strains for a given stress and, as expected, this resulted in higher fatigue limits. Using 107 cycles to define a run-out also led to a lower fatigue limit. These results are important as most previous fatigue limit measurements utilized 106 cycles or less to define a run-out, and when lives as long as 107 cycles are used the tests are generally run at high cycle frequencies, thus leading to higher fatigue limits than those measured here.

Optimum Construction of Heating Coil for Domestic Induction Cooker

NASA Astrophysics Data System (ADS)

Sinha, Dola; Bandyopadhyay, Atanu; Sadhu, Pradip Kumar; Pal, Nitai

2010-10-01

The design and optimization of the parameters of heating coil is very important for the analytical analysis of high frequency inverter fed induction cooker. Moreover, accurate prediction of high frequency winding loss (i.e., losses due to skin and proximity effects) is necessary as the induction cooker used in power electronics applications. At high frequency current penetration in the induction coil circuit is very difficult for conducting wire due to skin-effect. To eradicate the skin effect heating coil is made up of bundle conductor i.e., litz wire. In this paper inductances and AC resistances of a litz-wire are calculated and optimized by considering the input parameters like wire type, shape, number of strand, number of spiral turn, number of twist per feet of heating coil and operating frequency. A high frequency half bridge series resonant mirror inverter circuit is used in this paper and taking the optimum values of inductance and ac resistance the circuit is simulated through PSPICE simulations. It has been noticed that the results are feasible enough for real implementation.

Mutagenic frequencies of site-specifically located O6-methylguanine in wild-type Escherichia coli and in a strain deficient in ada-methyltransferase.

PubMed

Rossi, S C; Topal, M D

1991-02-01

The adaptive response of Escherichia coli involves protection of the cells against the toxic and mutagenic consequences of exposure to high doses of a methylating agent by prior exposure to low doses of the agent. Ada protein, a major repair activity for O6-methylguanine, is activated to positively control the adaptive response; O6-methylguanine is one of the major mutagenic lesions produced by methylating agents. We investigated the mutation frequency of wild-type Escherichia coli and strains containing the ada-5 mutation in response to site-specifically synthesized O6-methylguanine under conditions in which the adaptive response was not induced. Site-directed mutagenesis and oligonucleotide self-selection techniques were used to isolate the progeny of M13mp18 DNAs constructed to contain O6-methylguanine at any of eight different positions. The progeny were isolated from E. coli strains isogeneic except for deficiency in Ada-methyltransferase repair, UvrABC excision repair, or both. The resulting O6-methylguanine mutation levels at each position were determined by using differential oligonucleotide hybridization. We found that the wild type had up to a 2.6-fold higher mutation frequency than ada-5 mutants. In addition, the mutation frequency varied with the position of the O6-methylguanine in the DNA in the wild type but not in ada-5 mutants; O6-methylguanine lesions at the 5' ends of runs of consecutive guanines gave the highest mutation frequencies. Determination of the mutation frequency of O6-methylguanine in wild-type and mutS cells showed that mismatch repair can affect O6-methylguanine mutation levels.

PWM Switching Frequency Effects on Eddy Current Sensors for Magnetically Suspended Flywheel Systems

NASA Technical Reports Server (NTRS)

Jansen, Ralph; Lebron, Ramon; Dever, Timothy P.; Birchenough, Arthur G.

2003-01-01

A flywheel magnetic bearing (MB) pulse width modulated power amplifier (PWM) configuration is selected to minimize noise generated by the PWMs in the flywheel position sensor system. Two types of noise are addressed: beat frequency noise caused by variations in PWM switching frequencies, and demodulation noise caused by demodulation of high order harmonics of the switching voltage into the MB control band. Beat frequency noise is eliminated by synchronizing the PWM switch frequencies, and demodulation noise is minimized by selection of a switching frequency which does not have harmonics at the carrier frequency of the sensor. The recommended MB PWM system has five synchronized PWMs switching at a non-integer harmonic of the sensor carrier.

Digital intermediate frequency QAM modulator using parallel processing

DOEpatents

Pao, Hsueh-Yuan [Livermore, CA; Tran, Binh-Nien [San Ramon, CA

2008-05-27

The digital Intermediate Frequency (IF) modulator applies to various modulation types and offers a simple and low cost method to implement a high-speed digital IF modulator using field programmable gate arrays (FPGAs). The architecture eliminates multipliers and sequential processing by storing the pre-computed modulated cosine and sine carriers in ROM look-up-tables (LUTs). The high-speed input data stream is parallel processed using the corresponding LUTs, which reduces the main processing speed, allowing the use of low cost FPGAs.

Microwave Frequency Polarizers

NASA Technical Reports Server (NTRS)

Ha, Vien The; Mirel, Paul; Kogut, Alan J.

2013-01-01

This article describes the fabrication and analysis of microwave frequency polarizing grids. The grids are designed to measure polarization from the cosmic microwave background. It is effective in the range of 500 to 1500 micron wavelength. It is cryogenic compatible and highly robust to high load impacts. Each grid is fabricated using an array of different assembly processes which vary in the types of tension mechanisms to the shape and size of the grids. We provide a comprehensive study on the analysis of the grids' wire heights, diameters, and spacing.

Autonomic nervous functions in fetal type Minamata disease patients: assessment of heart rate variability.

PubMed

Oka, Tomoko; Matsukura, Makoto; Okamoto, Miwako; Harada, Noriaki; Kitano, Takao; Miike, Teruhisa; Futatsuka, Makoto

2002-12-01

In order to assess the cardiovascular autonomic nervous functions in patients with fetal type Minamata disease (FMD), we investigated blood pressure (BP), and conducted time and frequency domain analysis of heart rate variability (HRV). Subjects were 9 patients in Meisuien recognized as FMD, and 13 healthy age matched control subjects. HRV and BP were assessed after subjects rested in a supine position for 10 minutes. Electrocardiographic (ECG) data were collected for 3 minutes during natural breathing. Time domain analysis (the average of R-R intervals [Mean RR], standard deviation of R-R intervals [SD RR], coefficient of variation [CV]), and frequency domain analysis by fast Fourier transformation (FFT) (power of low frequency [LF] and high frequency [HF] component, expressed in normalized units[nu]) were then conducted. In the time domain analysis, the mean RR of the FMD group was significantly lower than that of the control group. Neither SD RR nor CV showed significant differences between the two groups, but both tended to be lower in the FMD group. In the frequency domain analysis, the HF component of the FMD group was significantly lower than that of the control group. Pulse pressure (PP) was significantly lower in the FMD subjects. These findings suggest that parasympathetic nervous dysfunction might exist in FMD patients, who were exposed to high doses of methylmercury (MeHg) during the prenatal period. Decrease of PP might be due to degenerative changes of blood vessels driven by exposure to high doses of MeHg.

Severe Hypoglycemia and Diabetic Ketoacidosis among Youth with Type 1 Diabetes in the T1D Exchange Clinic Registry

PubMed Central

Cengiz, Eda; Xing, Dongyuan; Wong, Jenise C.; Wolfsdorf, Joseph I.; Haymond, Morey W.; Rewers, Arleta; Shanmugham, Satya; Tamborlane, William V.; Willi, Steven M.; Seiple, Diane L.; Miller, Kellee M.; DuBose, Stephanie N.; Beck, Roy W.

2014-01-01

Objective Severe hypoglycemia (SH) and diabetic ketoacidosis (DKA) are common serious acute complications of type 1 diabetes (T1D). The aim of this study was to determine the frequency of SH and DKA and identify factors related to their occurrence in the T1D Exchange pediatric and young adult cohort. Research Design and Methods The analysis included 13,487 participants in the T1D Exchange clinic registry aged 2-<26 years with T1D ≥2 years. Separate logistic regression models were used to evaluate the association of baseline demographic and clinical factors with the occurrence of SH or DKA in the prior 12 months. Results Non-White race, no private health insurance and lower household income were associated with higher frequencies of both SH and DKA (p<0.001). SH frequency was highest in children <6 years old (p=0.005), but across the age range, SH was not associated with HbA1c levels after controlling for other factors (p=0.72). DKA frequency was highest in adolescents (p<0.001) and associated with higher HbA1c (p<0.001). Conclusions Our data show that poor glycemic control increases the risk of DKA but does not protect against severe hypoglycemia in youth and young adults with type 1 diabetes. The high frequencies of SH and DKA observed in disadvantaged minorities with T1D highlight the need for targeted interventions and new treatment paradigms for patients in these high risk groups. PMID:23469984

Silicon Cluster Tool | Photovoltaic Research | NREL

Science.gov Websites

Material Deposition/Device Fabrication Very-high-frequency plasma-enhanced chemical vapor deposition (VHF PECVD) for microcrystalline silicon (µc-Si:H) Combinatorial plasma-enhanced chemical vapor deposition (Combi-PECVD) for p-type a-Si:H Plasma-enhanced chemical vapor deposition (PECVD) for n-type a-Si:H

Type 2 and type 3 burst theory

NASA Technical Reports Server (NTRS)

Smith, D. F.

1973-01-01

The present state of the theory of type 3 bursts is reviewed by dividing the problem into the exciting agency, radiation source, and propagation of radiation between the source and the observer. In-situ measurements indicate that the excitors are electron streams of energy about 40 keV which are continuously relaxing. An investigation of neutralization of an electron stream indicates that n sub s is much less than 100,000 n sub e, where n sub s is the stream density and n sub e the coronal electron density. In situ observations are consistent with this result. An analysis of propagation of electrons in the current sheets of coronal streamers shows that such propagation at heights greater than 1 solar radius is impossible. The mechanisms for radiation are reviewed; it is shown that fundamental radiation at high frequencies (approximately 100 MHz) is highly beamed in the radial direction and that near the earth second harmonic radiation must be dominant. Because of beaming of the fundamental at high frequencies, it can often be quite weak near the limb so that the second harmonic is dominant. In considering propagation to the observer, the results of scattering of radiation are discussed. The present state of the theory of type 2 bursts is reviewed in the same manner as type 3 bursts.

Influence of excitation frequency on the metastable atoms and electron energy distribution function in a capacitively coupled argon discharge

NASA Astrophysics Data System (ADS)

Sharma, S.; Sirse, N.; Turner, M. M.; Ellingboe, A. R.

2018-06-01

One-dimensional particle-in-cell simulation is used to simulate the capacitively coupled argon plasma for a range of excitation frequency from 13.56 MHz to 100 MHz. The argon chemistry set can, selectively, include two metastable levels enabling multi-step ionization and metastable pooling. The results show that the plasma density decreases when metastable atoms are included with higher discrepancy at a higher excitation frequency. The contribution of multistep ionization to the overall density increases with the excitation frequency. The electron temperature increases with the inclusion of metastable atoms and decreases with the excitation frequency. At a lower excitation frequency, the density of Ar** (3p5 4p, 13.1 eV) is higher than that of Ar* (3p5 4s, 11.6 eV), whereas at higher excitation frequencies, the Ar* (3p5 4s, 11.6 eV) is the dominant metastable atom. The metastable and electron temperature profile evolve from a parabolic profile at a lower excitation frequency to a saddle type profile at a higher excitation frequency. With metastable, the electron energy distribution function (EEDF) changes its shape from Druyvesteyn type, at a low excitation frequency, to bi-Maxwellian, at a high frequency plasma excitation; however, a three-temperature EEDF is observed without metastable atoms.

Push-Broom-Type Very High-Resolution Satellite Sensor Data Correction Using Combined Wavelet-Fourier and Multiscale Non-Local Means Filtering.

PubMed

Kang, Wonseok; Yu, Soohwan; Seo, Doochun; Jeong, Jaeheon; Paik, Joonki

2015-09-10

In very high-resolution (VHR) push-broom-type satellite sensor data, both destriping and denoising methods have become chronic problems and attracted major research advances in the remote sensing fields. Since the estimation of the original image from a noisy input is an ill-posed problem, a simple noise removal algorithm cannot preserve the radiometric integrity of satellite data. To solve these problems, we present a novel method to correct VHR data acquired by a push-broom-type sensor by combining wavelet-Fourier and multiscale non-local means (NLM) filters. After the wavelet-Fourier filter separates the stripe noise from the mixed noise in the wavelet low- and selected high-frequency sub-bands, random noise is removed using the multiscale NLM filter in both low- and high-frequency sub-bands without loss of image detail. The performance of the proposed method is compared to various existing methods on a set of push-broom-type sensor data acquired by Korean Multi-Purpose Satellite 3 (KOMPSAT-3) with severe stripe and random noise, and the results of the proposed method show significantly improved enhancement results over existing state-of-the-art methods in terms of both qualitative and quantitative assessments.

Push-Broom-Type Very High-Resolution Satellite Sensor Data Correction Using Combined Wavelet-Fourier and Multiscale Non-Local Means Filtering

PubMed Central

Kang, Wonseok; Yu, Soohwan; Seo, Doochun; Jeong, Jaeheon; Paik, Joonki

2015-01-01

In very high-resolution (VHR) push-broom-type satellite sensor data, both destriping and denoising methods have become chronic problems and attracted major research advances in the remote sensing fields. Since the estimation of the original image from a noisy input is an ill-posed problem, a simple noise removal algorithm cannot preserve the radiometric integrity of satellite data. To solve these problems, we present a novel method to correct VHR data acquired by a push-broom-type sensor by combining wavelet-Fourier and multiscale non-local means (NLM) filters. After the wavelet-Fourier filter separates the stripe noise from the mixed noise in the wavelet low- and selected high-frequency sub-bands, random noise is removed using the multiscale NLM filter in both low- and high-frequency sub-bands without loss of image detail. The performance of the proposed method is compared to various existing methods on a set of push-broom-type sensor data acquired by Korean Multi-Purpose Satellite 3 (KOMPSAT-3) with severe stripe and random noise, and the results of the proposed method show significantly improved enhancement results over existing state-of-the-art methods in terms of both qualitative and quantitative assessments. PMID:26378532

Investigating the performance of reconstruction methods used in structured illumination microscopy as a function of the illumination pattern's modulation frequency

NASA Astrophysics Data System (ADS)

Shabani, H.; Sánchez-Ortiga, E.; Preza, C.

2016-03-01

Surpassing the resolution of optical microscopy defined by the Abbe diffraction limit, while simultaneously achieving optical sectioning, is a challenging problem particularly for live cell imaging of thick samples. Among a few developing techniques, structured illumination microscopy (SIM) addresses this challenge by imposing higher frequency information into the observable frequency band confined by the optical transfer function (OTF) of a conventional microscope either doubling the spatial resolution or filling the missing cone based on the spatial frequency of the pattern when the patterned illumination is two-dimensional. Standard reconstruction methods for SIM decompose the low and high frequency components from the recorded low-resolution images and then combine them to reach a high-resolution image. In contrast, model-based approaches rely on iterative optimization approaches to minimize the error between estimated and forward images. In this paper, we study the performance of both groups of methods by simulating fluorescence microscopy images from different type of objects (ranging from simulated two-point sources to extended objects). These simulations are used to investigate the methods' effectiveness on restoring objects with various types of power spectrum when modulation frequency of the patterned illumination is changing from zero to the incoherent cut-off frequency of the imaging system. Our results show that increasing the amount of imposed information by using a higher modulation frequency of the illumination pattern does not always yield a better restoration performance, which was found to be depended on the underlying object. Results from model-based restoration show performance improvement, quantified by an up to 62% drop in the mean square error compared to standard reconstruction, with increasing modulation frequency. However, we found cases for which results obtained with standard reconstruction methods do not always follow the same trend.

Manipulations of word frequency reveal differences in the processing of morphologically complex and simple words in German

PubMed Central

Bronk, Maria; Zwitserlood, Pienie; Bölte, Jens

2013-01-01

We tested current models of morphological processing in reading with data from four visual lexical decision experiments using German compounds and monomorphemic words. Triplets of two semantically transparent noun-noun compounds and one monomorphemic noun were used in Experiments 1a and 1b. Stimuli within a triplet were matched for full-form frequency. The frequency of the compounds' constituents was varied. The compounds of a triplet shared one constituent, while the frequency of the unshared constituent was either high or low, but always higher than full-form frequency. Reactions were faster to compounds with high-frequency constituents than to compounds with low-frequency constituents, while the latter did not differ from the monomorphemic words. This pattern was not influenced by task difficulty, induced by the type of pseudocompounds used. Pseudocompounds were either created by altering letters of an existing compound (easy pseudocompound, Experiment 1a) or by combining two free morphemes into a non-existing, but morphologically legal, compound (difficult pseudocompound, Experiment 1b). In Experiments 2a and 2b, frequency-matched pairs of semantically opaque noun-noun compounds and simple nouns were tested. In Experiment 2a, with easy pseudocompounds (of the same type as in Experiment 1a), a reaction-time advantage for compounds over monomorphemic words was again observed. This advantage disappeared in Experiment 2b, where difficult pseudocompounds were used. Although a dual-route might account for the data, the findings are best understood in terms of decomposition of low-frequency complex words prior to lexical access, followed by processing costs due to the recombination of morphemes for meaning access. These processing costs vary as a function of intrinsic factors such as semantic transparency, or external factors such as the difficulty of the experimental task. PMID:23986731

AIN-Coated Al(2)O(3) Substrates For Electronic Circuits

NASA Technical Reports Server (NTRS)

Kolawa, Elzbieta; Lowry, Lynn; Herman, Martin; Lee, Karen

1996-01-01

Type of improved ceramic substrate for high-frequency, high-power electronic circuits combines relatively high thermal conductivity of aluminum nitride with surface smoothness of alumina. Consists of 15-micrometer layer of AIN deposited on highly polished alumina. Used for packaging millimeter-wave gallium arsenide transmitter chips, power silicon chips, and like.

Motion mechanisms with different spatiotemporal characteristics identified by an MAE technique with superimposed gratings.

PubMed

Shioiri, Satoshi; Matsumiya, Kazumichi

2009-05-29

We investigated spatiotemporal characteristics of motion mechanisms using a new type of motion aftereffect (MAE) we found. Our stimulus comprised two superimposed sinusoidal gratings with different spatial frequencies. After exposure to the moving stimulus, observers perceived the MAE in the static test in the direction opposite to that of the high spatial frequency grating even when low spatial frequency motion was perceived during adaptation. In contrast, in the flicker test, the MAE was perceived in the direction opposite to that of the low spatial frequency grating. These MAEs indicate that two different motion systems contribute to motion perception and can be isolated by using different test stimuli. Using a psychophysical technique based on the MAE, we investigated the differences between the two motion mechanisms. The results showed that the static MAE is the aftereffect of the motion system with a high spatial and low temporal frequency tuning (slow motion detector) and the flicker MAE is the aftereffect of the motion system with a low spatial and high temporal frequency tuning (fast motion detector). We also revealed that the two motion detectors differ in orientation tuning, temporal frequency tuning, and sensitivity to relative motion.

Direct EPR irradiation of a sample using a quartz oscillator operating at 250 MHz for EPR measurements.

PubMed

Yokoyama, Hidekatsu

2012-01-01

Direct irradiation of a sample using a quartz oscillator operating at 250 MHz was performed for EPR measurements. Because a quartz oscillator is a frequency fixed oscillator, the operating frequency of an EPR resonator (loop-gap type) was tuned to that of the quartz oscillator by using a single-turn coil with a varactor diode attached (frequency shift coil). Because the frequency shift coil was mobile, the distance between the EPR resonator and the coil could be changed. Coarse control of the resonant frequency was achieved by changing this distance mechanically, while fine frequency control was implemented by changing the capacitance of the varactor electrically. In this condition, EPR measurements of a phantom (comprised of agar with a nitroxide radical and physiological saline solution) were made. To compare the presented method with a conventional method, the EPR measurements were also done by using a synthesizer at the same EPR frequency. In the conventional method, the noise level increased at high irradiation power. Because such an increase in the noise was not observed in the presented method, high sensitivity was obtained at high irradiation power. Copyright © 2011 Elsevier Inc. All rights reserved.

Combined electromechanical impedance and fiber optic diagnosis of aerospace structures

NASA Astrophysics Data System (ADS)

Schlavin, Jon; Zagrai, Andrei; Clemens, Rebecca; Black, Richard J.; Costa, Joey; Moslehi, Behzad; Patel, Ronak; Sotoudeh, Vahid; Faridian, Fereydoun

2014-03-01

Electromechanical impedance is a popular diagnostic method for assessing structural conditions at high frequencies. It has been utilized, and shown utility, in aeronautic, space, naval, civil, mechanical, and other types of structures. By contrast, fiber optic sensing initially found its niche in static strain measurement and low frequency structural dynamic testing. Any low frequency limitations of the fiber optic sensing, however, are mainly governed by its hardware elements. As hardware improves, so does the bandwidth (frequency range * number of sensors) provided by the appropriate enabling fiber optic sensor interrogation system. In this contribution we demonstrate simultaneous high frequency measurements using fiber optic and electromechanical impedance structural health monitoring technologies. A laboratory specimen imitating an aircraft wing structure, incorporating surfaces with adjustable boundary conditions, was instrumented with piezoelectric and fiber optic sensors. Experiments were conducted at different structural boundary conditions associated with deterioration of structural health. High frequency dynamic responses were collected at multiple locations on a laboratory wing specimen and conclusions were drawn about correspondence between structural damage and dynamic signatures as well as correlation between electromechanical impedance and fiber optic sensors spectra. Theoretical investigation of the effect of boundary conditions on electromechanical impedance spectra is presented and connection to low frequency structural dynamics is suggested. It is envisioned that acquisition of high frequency structural dynamic responses with multiple fiber optic sensors may open new diagnostic capabilities for fiber optic sensing technologies.

Local regression type methods applied to the study of geophysics and high frequency financial data

NASA Astrophysics Data System (ADS)

Mariani, M. C.; Basu, K.

2014-09-01

In this work we applied locally weighted scatterplot smoothing techniques (Lowess/Loess) to Geophysical and high frequency financial data. We first analyze and apply this technique to the California earthquake geological data. A spatial analysis was performed to show that the estimation of the earthquake magnitude at a fixed location is very accurate up to the relative error of 0.01%. We also applied the same method to a high frequency data set arising in the financial sector and obtained similar satisfactory results. The application of this approach to the two different data sets demonstrates that the overall method is accurate and efficient, and the Lowess approach is much more desirable than the Loess method. The previous works studied the time series analysis; in this paper our local regression models perform a spatial analysis for the geophysics data providing different information. For the high frequency data, our models estimate the curve of best fit where data are dependent on time.

Extended high-frequency audiometry (9,000-20,000 Hz). Usefulness in audiological diagnosis.

PubMed

Rodríguez Valiente, Antonio; Roldán Fidalgo, Amaya; Villarreal, Ithzel M; García Berrocal, José R

2016-01-01

Early detection and appropriate treatment of hearing loss are essential to minimise the consequences of hearing loss. In addition to conventional audiometry (125-8,000 Hz), extended high-frequency audiometry (9,000-20,000 Hz) is available. This type of audiometry may be useful in early diagnosis of hearing loss in certain conditions, such as the ototoxic effect of cisplatin-based treatment, noise exposure or oral misunderstanding, especially in noisy environments. Eleven examples are shown in which extended high-frequency audiometry has been useful in early detection of hearing loss, despite the subject having a normal conventional audiometry. The goal of the present paper was to highlight the importance of the extended high-frequency audiometry examination for it to become a standard tool in routine audiological examinations. Copyright © 2015 Elsevier España, S.L.U. y Sociedad Española de Otorrinolaringología y Patología Cérvico-Facial. All rights reserved.

Single reflector interference spectrometer and drive system therefor

NASA Technical Reports Server (NTRS)

Schindler, R. A. (Inventor)

1974-01-01

In a Fourier interference spectrometer of the doublepass retroreflector type, a single mirror is employed in the path of both split beams of an incoming ray to cause them to double back through separate retroreflectors. Changes in optical path length are achieved by linear displacement of both retroreflectors using a motor driven lead screw on one for large, low frequency changes, a moving-coil actuator on the other for smaller, mid-frequency changes and a piezoelectric actuator on one of these two for small, high frequency changes.

Stereotypic Laryngeal and Respiratory Motor Patterns Generate Different Call Types in Rat Ultrasound Vocalization

PubMed Central

RIEDE, TOBIAS

2014-01-01

Rodents produce highly variable ultrasound whistles as communication signals unlike many other mammals, who employ flow-induced vocal fold oscillations to produce sound. The role of larynx muscles in controlling sound features across different call types in ultrasound vocalization (USV) was investigated using laryngeal muscle electromyographic (EMG) activity, subglottal pressure measurements and vocal sound output in awake and spontaneously behaving Sprague–Dawley rats. Results support the hypothesis that glottal shape determines fundamental frequency. EMG activities of thyroarytenoid and cricothyroid muscles were aligned with call duration. EMG intensity increased with fundamental frequency. Phasic activities of both muscles were aligned with fast changing fundamental frequency contours, for example in trills. Activities of the sternothyroid and sternohyoid muscles, two muscles involved in vocal production in other mammals, are not critical for the production of rat USV. To test how stereotypic laryngeal and respiratory activity are across call types and individuals, sets of ten EMG and subglottal pressure parameters were measured in six different call types from six rats. Using discriminant function analysis, on average 80% of parameter sets were correctly assigned to their respective call type. This was significantly higher than the chance level. Since fundamental frequency features of USV are tightly associated with stereotypic activity of intrinsic laryngeal muscles and muscles contributing to build-up of subglottal pressure, USV provide insight into the neurophysiological control of peripheral vocal motor patterns. PMID:23423862

Design of magneto-rheological mount for a cabin of heavy equipment vehicles

NASA Astrophysics Data System (ADS)

Yang, Soon-Yong; Do, Xuan Phu; Choi, Seung-Bok

2016-04-01

In this paper, magneto-rheological (MR) mount for a cabin of heavy equipment vehicles is designed for improving vibration isolation in both low and high frequency domains. The proposed mount consists of two principal parts of mount, rubber part and MR fluid path. The rubber part of existed mount and spring are used to change the stiffness and frequency characteristics for low vibration frequency range. The MR fluid path is a valve type structure using flow mode. In order to control the external magnetic field, a solenoid coil is placed in MR mount. Magnetic intensity analysis is then conducted to optimize dimensions using computer simulation. Experimental results show that magnetic field can reduce low frequency vibration. The results presented in this work indicate that proper application of MR fluid and rubber characteristic to devise MR mount can lead to the improvement of vibration control performance in both low and high frequency ranges.

Radio frequency diodes and circuits fabricated via adhesion lithography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Georgiadou, Dimitra G.; Semple, James; Wyatt-Moon, Gwenhivir; Anthopoulos, Thomas D.

2016-09-01

The commercial interest in Radio Frequency Identification (RFID) tags keeps growing, as new application sectors, spanning from healthcare to electronic article surveillance (EAS) and personal identification, are constantly emerging for these types of electronic devices. The increasing demand for the so-called "smart labels" necessitates their high throughput manufacturing, and indeed on thin flexible substrates, that will reduce the cost and render them competitive to the currently widely employed barcodes. Adhesion Lithography (a-Lith) is a novel patterning technique that allows the facile high yield fabrication of co-planar large aspect ratio (<100,000) metal electrodes separated by a sub-20 nm gap on large area substrates of any type. Deposition of high mobility semiconductors from their solution at low, compatible with plastic substrates, temperatures and application of specific processing protocols can dramatically improve the performance of the fabricated Schottky diodes. It will be shown that in this manner both organic and inorganic high speed diodes and rectifiers can be obtained, operating at frequencies much higher than the 13.56 MHz benchmark, currently employed in passive RFID tags and near filed communications (NFC). This showcases the universality of this method towards fabricating high speed p- and n-type diodes, irrespective of the substrate, simply based on the extreme downscaling of key device dimensions obtained in these nanoscale structures. The potential for scaling up this technique at low cost, combined with the significant performance optimisation and improved functionality that can be attained through intelligent material selection, render a-Lith unique within the field of plastic electronics.

Power spectrum model of visual masking: simulations and empirical data.

PubMed

Serrano-Pedraza, Ignacio; Sierra-Vázquez, Vicente; Derrington, Andrew M

2013-06-01

In the study of the spatial characteristics of the visual channels, the power spectrum model of visual masking is one of the most widely used. When the task is to detect a signal masked by visual noise, this classical model assumes that the signal and the noise are previously processed by a bank of linear channels and that the power of the signal at threshold is proportional to the power of the noise passing through the visual channel that mediates detection. The model also assumes that this visual channel will have the highest ratio of signal power to noise power at its output. According to this, there are masking conditions where the highest signal-to-noise ratio (SNR) occurs in a channel centered in a spatial frequency different from the spatial frequency of the signal (off-frequency looking). Under these conditions the channel mediating detection could vary with the type of noise used in the masking experiment and this could affect the estimation of the shape and the bandwidth of the visual channels. It is generally believed that notched noise, white noise and double bandpass noise prevent off-frequency looking, and high-pass, low-pass and bandpass noises can promote it independently of the channel's shape. In this study, by means of a procedure that finds the channel that maximizes the SNR at its output, we performed numerical simulations using the power spectrum model to study the characteristics of masking caused by six types of one-dimensional noise (white, high-pass, low-pass, bandpass, notched, and double bandpass) for two types of channel's shape (symmetric and asymmetric). Our simulations confirm that (1) high-pass, low-pass, and bandpass noises do not prevent the off-frequency looking, (2) white noise satisfactorily prevents the off-frequency looking independently of the shape and bandwidth of the visual channel, and interestingly we proved for the first time that (3) notched and double bandpass noises prevent off-frequency looking only when the noise cutoffs around the spatial frequency of the signal match the shape of the visual channel (symmetric or asymmetric) involved in the detection. In order to test the explanatory power of the model with empirical data, we performed six visual masking experiments. We show that this model, with only two free parameters, fits the empirical masking data with high precision. Finally, we provide equations of the power spectrum model for six masking noises used in the simulations and in the experiments.

Manual therapy for tension-type headache related to quality of work life and work presenteeism: Secondary analysis of a randomized controlled trial.

PubMed

Monzani, Lucas; Espí-López, Gemma Victoria; Zurriaga, Rosario; Andersen, Lars L

2016-04-01

The objective of this research is to evaluate the efficacy of manual therapy for tension-type headache (TTH) in restoring workers quality of work life, and how work presenteeism affects this relation. This study is a secondary analysis of a factorial, randomized clinical trial on manual therapy interventions. Altogether, 80 patients (85% women) with TTH and without current symptoms of any other concomitant disease participated. An experienced therapist delivered the treatment: myofascial inhibitory technique (IT), articulatory technique (AT), combined technique (IT and AT), and control group (no treatment). In general, all treatments as compared to our control group had a large effect (f≥.69) in the improvement of participants' quality of work life. Work presenteeism interacted with TTH treatment type's efficacy on participant's quality of work life. The inhibitory technique lead to higher reports of quality of work life than other treatment options only for participants with very low frequency of work presenteeism. In turn, TTH articulatory treatment techniques resulted in higher reports of quality of work life for a high to very high work presenteeism frequency. Articulatory manipulation technique is the more efficient treatment to improve quality of work life when the frequency of work presenteeism is high. Implications for future research and practice are discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nonlinear generation of sum and difference frequency waves by two helicon waves in a semiconductor

NASA Astrophysics Data System (ADS)

Salimullah, M.; Ferdous, T.

1984-05-01

This paper presents a theoretical investigation of the nonlinear generation of electrostatic waves at the sum and the difference frequency when two high amplitude elliptically polarized helicon waves propagate along the direction of the externally applied static magnetic field in an n-type semiconductor. The nonlinearity arises through the ponderomotive force on electrons. It is noticed that the power conversion efficiency of the difference frequency generation is much larger than that of the sum frequency generation. The power conversion efficiency may be easily increased by increasing the density of electrons in the semiconductor.

Ultrahigh contrast from a frequency-doubled chirped-pulse-amplification beamline.

PubMed

Hillier, David; Danson, Colin; Duffield, Stuart; Egan, David; Elsmere, Stephen; Girling, Mark; Harvey, Ewan; Hopps, Nicholas; Norman, Michael; Parker, Stefan; Treadwell, Paul; Winter, David; Bett, Thomas

2013-06-20

This paper describes frequency-doubled operation of a high-energy chirped-pulse-amplification beamline. Efficient type-I second-harmonic generation was achieved using a 3 mm thick 320 mm aperture KDP crystal. Shots were fired at a range of energies achieving more than 100 J in a subpicosecond, 527 nm laser pulse with a power contrast of 10(14).

Frequency and Correlates of Spouse Abuse by Type: Physical, Sexual and Psychological Battering among a Sample of Iranian Women

ERIC Educational Resources Information Center

Zand, Ramin

2008-01-01

Introduction: Violence against women is one of the main, yet neglected, social problem in many countries. Unpublished reports and other anecdotes suggest a high rate of violence against women in Iran. This preliminary study was developed to examine the frequency and correlates of physical, sexual, and psychological violence against women in this…

Redintegration and the benefits of long-term knowledge in verbal short-term memory: an evaluation of Schweickert's (1993) multinomial processing tree model.

PubMed

Thorn, Annabel S C; Gathercole, Susan E; Frankish, Clive R

2005-03-01

The impact of four long-term knowledge variables on serial recall accuracy was investigated. Serial recall was tested for high and low frequency words and high and low phonotactic frequency nonwords in 2 groups: monolingual English speakers and French-English bilinguals. For both groups the recall advantage for words over nonwords reflected more fully correct recalls with fewer recall attempts that consisted of fragments of the target memory items (one or two of the three target phonemes recalled correctly); completely incorrect recalls were equivalent for the 2 list types. However, word frequency (for both groups), nonword phonotactic frequency (for the monolingual group), and language familiarity all influenced the proportions of completely incorrect recalls that were made. These results are not consistent with the view that long-term knowledge influences on immediate recall accuracy can be exclusively attributed to a redintegration process of the type specified in multinomial processing tree model of immediate recall. The finding of a differential influence on completely incorrect recalls of these four long-term knowledge variables suggests instead that the beneficial effects of long-term knowledge on short-term recall accuracy are mediated by more than one mechanism.

Stimulation of the cell cycle and maize transformation by disruption of the plant retinoblastoma pathway

PubMed Central

Gordon-Kamm, William; Dilkes, Brian P.; Lowe, Keith; Hoerster, George; Sun, Xifan; Ross, Margit; Church, Laura; Bunde, Chris; Farrell, Jeff; Hill, Patrea; Maddock, Sheila; Snyder, Jane; Sykes, Louisa; Li, Zhongsen; Woo, Young-min; Bidney, Dennis; Larkins, Brian A.

2002-01-01

The genome of the Mastreviruses encodes a replication-associated protein (RepA) that interacts with members of the plant retinoblastoma-related protein family, which are putative cell cycle regulators. Expression of ZmRb1, a maize retinoblastoma-related gene, and RepA inhibited and stimulated, respectively, cell division in tobacco cell cultures. The effect of RepA was mitigated by over-expression of ZmRb1. RepA increased transformation frequency and callus growth rate of high type II maize germplasm. RepA-containing transgenic maize calli remained embryogenic, were readily regenerable, and produced fertile plants that transmitted transgene expression in a Mendelian fashion. In high type II, transformation frequency increased with the strength of the promoter driving RepA expression. When a construct in which RepA was expressed behind its native LIR promoter was used, primary transformation frequencies did not improve for two elite Pioneer maize inbreds. However, when LIR:RepA-containing transgenic embryos were used in subsequent rounds of transformation, frequencies were higher in the RepA+ embryos. These data demonstrate that RepA can stimulate cell division and callus growth in culture, and improve maize transformation. PMID:12185243

Ultrasound

MedlinePlus

Ultrasound is a type of imaging. It uses high-frequency sound waves to look at organs and ... liver, and other organs. During pregnancy, doctors use ultrasound to view the fetus. Unlike x-rays, ultrasound ...

HLA DR phenotypic frequencies and genetic risk of Type 1 diabetes in west region of Algeria, Tlemcen

PubMed Central

Aribi, Mourad; Moulessehoul, Soraya; Benabadji, Ahmed-Bakir; Kendoucitani, Mohammed

2004-01-01

Background The main genomic region controlling the predisposition to type 1 diabetes is the Human Leukocyte Antigens (HLA) class II of the major histocompatibility complex. Association with different HLA types depends also on the studied populations. In our investigation, we tried to measure the phenotypic HLA class II association frequencies of DR3 and/or DR4 antigens, using a serologic method called microlymphocytotoxicity analysis, in diabetic and nondiabetic (ND) subjects originating from the west-Algerian region of Tlemcen. The aim of the present study was to determine which HLA DR antigens represent a high susceptibility to develop the disease in this area. Using a case-control retrospective study design, we randomly recruited ninety-one related subjects, 39 type 1 diabetics and 52 ND as controls, at the Internal Medicine Board of Medical Centre University of Tlemcen. Results DR3 antigen frequencies were comparable between the type 1 diabetics and the ND subjects and showed no association with the disease (p = 1.000, OR = 0.95), whereas DR4 and DR3DR4 antigens were associated with susceptibility to develop type 1 diabetes (DR4; OR = 2.10, DR3DR4; OR = 1.30). Also, no incidence for DR3 (p = 0.2646) or DR3DR4 (p = 0.0699) antigen frequencies was related to the sex ratio. However, significant differences in HLA DR4 frequencies between type 1 diabetics and ND were found to be related to sex (p = 0.0085). Conclusion Taken together, our investigation showed that the strongest association with type 1 diabetes was noticed in the presence of HLA DR4 antigens followed by DR3DR4 antigens. This study highlighted a characteristic of Tlemcen population; a history of consanguineous marriages. Association studies between the disease and genetic polymorphisms should be undertaken in a population where consanguinity is more limited to reduce confounding in result interpretations. PMID:15331022

Experimental evidence for real-time song frequency shift in response to urban noise in a passerine bird.

PubMed

Bermúdez-Cuamatzin, Eira; Ríos-Chelén, Alejandro A; Gil, Diego; Garcia, Constantino Macías

2011-02-23

Research has shown that bird songs are modified in different ways to deal with urban noise and promote signal transmission through noisy environments. Urban noise is composed of low frequencies, thus the observation that songs have a higher minimum frequency in noisy places suggests this is a way of avoiding noise masking. Most studies are correlative and there is as yet little experimental evidence that this is a short-term mechanism owing to individual plasticity. Here we experimentally test if house finches (Carpodacus mexicanus) can modulate the minimum frequency of their songs in response to different noise levels. We exposed singing males to three continuous treatments: low-high-low noise levels. We found a significant increase in minimum frequency from low to high and a decrement from high to low treatments. We also found that this was mostly achieved by modifying the frequency of the same low-frequency syllable types used in the different treatments. When different low-frequency syllables were used, those sung during the noisy condition were longer than the ones sang during the quiet condition. We conclude that house finches modify their songs in several ways in response to urban noise, thus providing evidence of a short-term acoustic adaptation.

Serial recall, word frequency, and mixed lists: the influence of item arrangement.

PubMed

Miller, Leonie M; Roodenrys, Steven

2012-11-01

Studies of the effect of word frequency in the serial recall task show that lists of high-frequency words are better recalled than lists of low-frequency words; however, when high- and low-frequency words are alternated within a list, there is no difference in the level of recall for the two types of words, and recall is intermediate between lists of pure frequency. This pattern has been argued to arise from the development of a network of activated long-term representations of list items that support the redintegration of all list items in a nondirectional and nonspecific way. More recently, it has been proposed that the frequency effect might be a product of the coarticulation of items at word boundaries and their influence on rehearsal rather than a consequence of memory representations. The current work examines recall performance in mixed lists of an equal number of high- and low-frequency items arranged in contiguous segments (i.e., HHHLLL and LLLHHH), under quiet and articulatory suppression conditions, to test whether the effect is (a) nondirectional and (b) dependent on articulatory processes. These experiments demonstrate that neither explanation is satisfactory, although the results suggest that the effect is mnemonic. A language-based approach to short-term memory is favored with emphasis on the role of speech production processes at output.

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.

Dynamic frequency-domain interferometer for absolute distance measurements with high resolution

NASA Astrophysics Data System (ADS)

Weng, Jidong; Liu, Shenggang; Ma, Heli; Tao, Tianjiong; Wang, Xiang; Liu, Cangli; Tan, Hua

2014-11-01

A unique dynamic frequency-domain interferometer for absolute distance measurement has been developed recently. This paper presents the working principle of the new interferometric system, which uses a photonic crystal fiber to transmit the wide-spectrum light beams and a high-speed streak camera or frame camera to record the interference stripes. Preliminary measurements of harmonic vibrations of a speaker, driven by a radio, and the changes in the tip clearance of a rotating gear wheel show that this new type of interferometer has the ability to perform absolute distance measurements both with high time- and distance-resolution.

Calcium channel dynamics limit synaptic release in response to prosthetic stimulation with sinusoidal waveforms

PubMed Central

Freeman, Daniel K.; Jeng, Jed S.; Kelly, Shawn K.; Hartveit, Espen; Fried, Shelley I.

2011-01-01

Extracellular electric stimulation with sinusoidal waveforms has been shown to allow preferential activation of individual types of retinal neurons by varying stimulus frequency. It is important to understand the mechanisms underlying this frequency dependence as a step towards improving methods of preferential activation. In order to elucidate these mechanisms, we implemented a morphologically realistic model of a retinal bipolar cell and measured the response to extracellular stimulation with sinusoidal waveforms. We compared the frequency response of a passive membrane model to the kinetics of voltage-gated calcium channels that mediate synaptic release. The passive electrical properties of the membrane exhibited lowpass filtering with a relatively high cutoff frequency (nominal value = 717 Hz). This cutoff frequency was dependent on intra-axonal resistance, with shorter and wider axons yielding higher cutoff frequencies. However, we found that the cutoff frequency of bipolar cell synaptic release was primarily limited by the relatively slow opening kinetics of Land T-type calcium channels. The cutoff frequency of calcium currents depended nonlinearly on stimulus amplitude, but remained lower than the cutoff frequency of the passive membrane model for a large range of membrane potential fluctuations. These results suggest that while it may be possible to modulate the membrane potential of bipolar cells over a wide range of stimulus frequencies, synaptic release will only be initiated at the lower end of this range. PMID:21628768

The responses of subjective feeling, task performance ability, cortisol and HRV for the various types of floor impact sound: a pilot study.

PubMed

Yun, Seok Hyeon; Park, Sang Jin; Sim, Chang Sun; Sung, Joo Hyun; Kim, Ahra; Lee, Jang Myeong; Lee, Sang Hyun; Lee, Jiho

2017-01-01

Recently, noise coming from the neighborhood via floor wall has become a great social problem. The noise between the floors can be a cause of physical and psychological problems, and the different types of floor impact sound (FIS) may have the different effects on the human's body and mind. The purpose of this study is to assess the responses of subjective feeling, task performance ability, cortisol and HRV for the various types of floor impact. Ten men and 5 women were enrolled in our study, and the English listening test was performed under the twelve different types of FIS, which were made by the combinations of bang machine (B), tapping machine (T), impact ball (I) and sound-proof mattress (M). The 15 subjects were exposed to each FIS for about 3 min, and the subjective annoyance, performance ability (English listening test), cortisol level of urine/saliva and heart rate variability (HRV) were examined. The sound pressure level (SPL) and frequency of FIS were analyzed. Repeated-measures ANOVA, paired t-test, Wilcoxon signed rank test were performed for data analysis. The SPL of tapping machine (T) was reduced with the soundproof mattress (M) by 3.9-7.3 dBA. Impact ball (I) was higher than other FIS in low frequency (31.5-125 Hz) by 10 dBA, and tapping machine (T) was higher than other FIS in high frequency (2-4 k Hz) by 10 dBA. The subjective annoyance is highest in the combination of bang machine and tapping machine (BT), and next in the tapping machine (T). The English listening score was also lowest in the BT, and next in T. The difference of salivary cortisol levels between various types of FIS was significant ( p  = 0.003). The change of HRV parameters by the change of FIS types was significant in some parameters, which were total power (TP) ( p  = 0.004), low frequency (LF) ( p  = 0.002) and high frequency (HF) ( p  = 0.011). These results suggest that the human's subjective and objective responses were different according to FIS types and those combinations.

A "caliper" type of controlled-source, frequency-domain, electromagnetic sounding method

NASA Astrophysics Data System (ADS)

Zhang, W.; Lin, J.; Zhou, F.; Liu, C.; Chen, J.; Xue, K.; Liu, L.; Wu, Y.

2011-12-01

We developed a special measurement manner for controlled-source, frequency-domain, electromagnetic sounding method that can improve resolution and efficiency, called as "caliper". This manner is base on our array electromagnetic system DPS-I, which consists of 53 channels and can cover 2500 m survey line at one arrangement. There are several steps to apply this method. First, a rough measurement is carried out, using large dynamic range but sparse frequencies. The ratio of adjacent frequency is set to be 2 or 4. The frequency points cover the entire frequency band that is required according to the geological environment, and are almost equidistantly distributed at logarithmic axis. Receivers array are arranged in one or more survey lines to measure the amplitude and phase of electromagnetic field components simultaneously. After all frequency points for rough measurement are measured, data in each sub-receiver are transmitted to the controller and the apparent resistivity and phase are calculated in field quickly. Then the pseudo section diagrams of apparent resistivity and phase are drew. By the pseudo section we can roughly lock the abnormal zone and determine the frequency band required for detail investigation of abnormal zone. Next, the measurement using high density of frequencies in this frequency band is carried out, which we called "detailed measurement". The ratio of adjacent frequency in this time is m which lies between 1 and 2. The exact value of m will depend on how detailed that the user expected. After "detailed measurement" is finished, the pseudo section diagrams of apparent resistivity and phase are drew in the same way with the first step. We can see more detailed information about the abnormal zone and decide whether further measurement is necessary. If it is necessary, we can repeat the second step using smaller m until the resolution meet the requirements to distinguish the target. By simulation, we know that high density of frequencies really help us to improve resolution. But we also need to say that the improvement is limited and it will do no help to add frequencies if the frequency is already dense enough. This method not only improves efficiency, but also improves the ability to distinguish the abnormal body. This measurement mode consisting of rough measurement and detailed measurement is similar to the caliper measurement of length, so called "caliper" type. It is accurate and fast. It not only can be applied to frequency-domain sounding, such as controlled source audio -frequency magnetotelluric (CSAMT), but also can be extended to the spectral induced polarization method. By using this measurement manner, high resolution and high-efficiency can be expected.

Influence of text type, topic familiarity, and stuttering frequency on listener recall, comprehension, and mental effort.

PubMed

Panico, James; Healey, E Charles

2009-04-01

To determine how text type, topic familiarity, and stuttering frequency influence listener recall, comprehension, and perceived mental effort. Sixty adults listened to familiar and unfamiliar narrative and expository texts produced with 0%, 5%, 10%, and 15% stuttering. Participants listened to 4 experimental text samples at only 1 stuttering frequency. After hearing the text samples, each listener performed a free recall task, answered cued recall questions, answered story comprehension questions, and rated their perceived mental effort. Free and cued recall as well as story comprehension scores were higher for narrative than for expository texts. Free and cued recall scores were better for familiar than for unfamiliar stories, although topic familiarity did not affect story comprehension scores. Samples with all levels of stuttering resulted in higher mental effort ratings for both text types and topic familiarities. Stuttering has a greater influence on listener recall and comprehension for narrative than for expository texts. Topic familiarity affects free and cued recall but has no influence on story comprehension. Regardless of the amount of stuttering, mental effort was high for both text types and levels of familiarity.

Study of noise reduction characteristics of double-wall panels

NASA Technical Reports Server (NTRS)

Navaneethan, R.; Quayle, B.; Stevenson, S.; Graham, M.

1983-01-01

The noise reduction characteristics of general aviation type, flat, double-wall structures were investigated. The experimental study was carried out on 20-by-20 inch panels with an exposed area of 18 by 18 inches. A frequency range from 20 to 5000 Hz was covered. The experimental results, in general, follow the expected trends. At low frequencies the double-wall structures are no better than the single-wall structures. However, for depths normally used in the general aviation industry, the double-wall panels are very attractive. The graphite-spoxy skin panels have higher noise reduction at very low frequencies ( 100 Hz) than the Kevlar skin panels. But the aluminum panels have higher noise reduction in the high frequency region, due to their greater mass. Use of fiberglass insulation is not effective in the low frequency region, and at times it is even negative. But the insulation is effective in the high-frequency region. The theoretical model for predicting the transmission loss of these multilayered panels is also discussed.

Study of noise reduction characteristics of double-wall panels

NASA Astrophysics Data System (ADS)

Navaneethan, R.; Quayle, B.; Stevenson, S.; Graham, M.

1983-05-01

The noise reduction characteristics of general aviation type, flat, double-wall structures were investigated. The experimental study was carried out on 20-by-20 inch panels with an exposed area of 18 by 18 inches. A frequency range from 20 to 5000 Hz was covered. The experimental results, in general, follow the expected trends. At low frequencies the double-wall structures are no better than the single-wall structures. However, for depths normally used in the general aviation industry, the double-wall panels are very attractive. The graphite-spoxy skin panels have higher noise reduction at very low frequencies ( 100 Hz) than the Kevlar skin panels. But the aluminum panels have higher noise reduction in the high frequency region, due to their greater mass. Use of fiberglass insulation is not effective in the low frequency region, and at times it is even negative. But the insulation is effective in the high-frequency region. The theoretical model for predicting the transmission loss of these multilayered panels is also discussed.

Frequency-dependent response of SI RA-class neurons to vibrotactile stimulation of the receptive field.

PubMed

Whitsel, B L; Kelly, E F; Xu, M; Tommerdahl, M; Quibrera, M

2001-01-01

Three types of experiment were carried out on anesthetized monkeys and cats. In the first, spike discharge activity of rapidly adapting (RA) SI neurons was recorded extracellularly during the application of different frequencies of vibrotactile stimulation to the receptive field (RF). The second used the same stimulus conditions to study the response of RA-I (RA) cutaneous mechanoreceptive afferents. The third used optical intrinsic signal (OIS) imaging and extracellular neurophysiological recording methods together, in the same sessions, to evaluate the relationship between the SI optical and RA neuron spike train responses to low- vs high-frequency stimulation of the same skin site. RA afferent entrainment was high at all frequencies of stimulation. In contrast, SI RA neuron entrainment was much lower on average, and was strongly frequency-dependent, declining in near-linear fashion from 6 to 200 Hz. Even at 200 Hz, however, unambiguous frequency-following responses were present in the spike train activity of som

Radar error statistics for the space shuttle

NASA Technical Reports Server (NTRS)

Lear, W. M.

1979-01-01

Radar error statistics of C-band and S-band that are recommended for use with the groundtracking programs to process space shuttle tracking data are presented. The statistics are divided into two parts: bias error statistics, using the subscript B, and high frequency error statistics, using the subscript q. Bias errors may be slowly varying to constant. High frequency random errors (noise) are rapidly varying and may or may not be correlated from sample to sample. Bias errors were mainly due to hardware defects and to errors in correction for atmospheric refraction effects. High frequency noise was mainly due to hardware and due to atmospheric scintillation. Three types of atmospheric scintillation were identified: horizontal, vertical, and line of sight. This was the first time that horizontal and line of sight scintillations were identified.

Validation of the Voice of America Coverage Analysis Program (VOACAP)

DTIC Science & Technology

2013-02-01

related to receiver characteristics or man-made noise, for example. Parameters such as Transmitter Frequency, Receiver Latitude /Longitude and Sunspot... Transmitter > <Frequency Unit="MHz">10</Frequency> <Type>0</Type> < Latitude Unit="deg">32</ Latitude ... Transmitter > <Frequency Unit="MHz">10.00</Frequency> <Type>0</Type> < Latitude Unit="deg">32</ Latitude

Kinematic-PPP using Single/Dual Frequency Observations from (GPS, GLONASS and GPS/GLONASS) Constellations for Hydrography

NASA Astrophysics Data System (ADS)

Farah, Ashraf

2018-03-01

Global Positioning System (GPS) technology is ideally suited for inshore and offshore positioning because of its high accuracy and the short observation time required for a position fix. Precise point positioning (PPP) is a technique used for position computation with a high accuracy using a single GNSS receiver. It relies on highly accurate satellite position and clock data that can be acquired from different sources such as the International GNSS Service (IGS). PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of observations among other factors. PPP offers comparable accuracy to differential GPS with safe in cost and time. For many years, PPP users depended on GPS (American system) which considered the solely reliable system. GLONASS's contribution in PPP techniques was limited due to fail in maintaining full constellation. Yet, GLONASS limited observations could be integrated into GPS-based PPP to improve availability and precision. As GLONASS reached its full constellation early 2013, there is a wide interest in PPP systems based on GLONASS only and independent of GPS. This paper investigates the performance of kinematic PPP solution for the hydrographic applications in the Nile river (Aswan, Egypt) based on GPS, GLONASS and GPS/GLONASS constellations. The study investigates also the effect of using two different observation types; single-frequency and dual frequency observations from the tested constellations.

Hyperglycemia is associated with simultaneous alterations in electrical brain activity in youths with type 1 diabetes mellitus.

PubMed

Rachmiel, M; Cohen, M; Heymen, E; Lezinger, M; Inbar, D; Gilat, S; Bistritzer, T; Leshem, G; Kan-Dror, E; Lahat, E; Ekstein, D

2016-02-01

To assess the association between hyperglycemia and electrical brain activity in type 1 diabetes mellitus (T1DM). Nine youths with T1DM were monitored simultaneously and continuously by EEG and continuous glucose monitor system, for 40 h. EEG powers of 0.5-80 Hz frequency bands in all the different brain regions were analyzed according to interstitial glucose concentration (IGC) ranges of 4-11 mmol/l, 11-15.5 mmol/l and >15.5 mmol/l. Analysis of variance was used to examine the differences in EEG power of each frequency band between the subgroups of IGC. Analysis was performed separately during wakefulness and sleep, controlling for age, gender and HbA1c. Mean IGC was 11.49 ± 5.26 mmol/l in 1253 combined measurements. IGC>15.5 mmol/l compared to 4-11 mmol/l was associated during wakefulness with increased EEG power of low frequencies and with decreased EEG power of high frequencies. During sleep, it was associated with increased EEG power of low frequencies in all brain areas and of high frequencies in frontal and central areas. Asymptomatic transient hyperglycemia in youth with T1DM is associated with simultaneous alterations in electrical brain activity during wakefulness and sleep. The clinical implications of immediate electrical brain alterations under hyperglycemia need to be studied and may lead to adaptations of management. Copyright © 2015. Published by Elsevier Ireland Ltd.

Characterization of site conditions for selected seismic stations in eastern part of Romania

NASA Astrophysics Data System (ADS)

Grecu, B.; Zaharia, B.; Diaconescu, M.; Bala, A.; Nastase, E.; Constantinescu, E.; Tataru, D.

2018-02-01

Strong motion data are essential for seismic hazard assessment. To correctly understand and use this kind of data is necessary to have a good knowledge of local site conditions. Romania has one of the largest strong motion networks in Europe with 134 real-time stations. In this work, we aim to do a comprehensive site characterization for eight of these stations located in the eastern part of Romania. We make use of a various seismological dataset and we perform ambient noise and earthquake-based investigations to estimate the background noise level, the resonance frequencies and amplification of each site. We also derive the Vs30 parameter from the surface shear-wave velocity profiles obtained through the inversion of the Rayleigh waves recorded in active seismic measurements. Our analyses indicate similar results for seven stations: high noise levels for frequencies larger than 1 Hz, well defined fundamental resonance at low frequencies (0.15-0.29 Hz), moderate amplification levels (up to 4 units) for frequencies between 0.15 and 5-7 Hz and same soil class (type C) according to the estimated Vs30 and Eurocode 8. In contrast, the eighth station for which the soil class is evaluated of type B exhibits a very good noise level for a wide range of frequencies (0.01-20 Hz), a broader fundamental resonance at high frequencies ( 8 Hz) and a flat amplification curve between 0.1 and 3-4 Hz.

Time-domain terahertz spectroscopy and applications on drugs and explosives

NASA Astrophysics Data System (ADS)

Fan, W. H.; Zhao, W.; Cheng, G. H.; Burnett, A. D.; Upadhya, P. C.; Cunningham, J. E.; Linfield, E. H.; Davies, A. G.

2008-03-01

Many materials of interest to the forensic and security services, such as explosives, drugs and biological agents, exhibit characteristic spectral features in the terahertz (THz) frequency range. These spectral features originate from inter-molecular interactions, involving collective motions of molecules. Broadband THz time-domain spectroscopy (THz-TDS) system have been used to analyze a number of drugs-of-abuse and explosives that are of interest to the forensic and security services. These samples ranged from crystalline powders, pressed into pellets, to thin sheets of plastic explosives, and all being measured in transmission geometry in the frequency range 0.1 - 8 THz. To well understand the nature of the observed spectral features and the effects of thermal broadening on these far-infrared signatures, temperature-dependent THz-TDS measurements have also been performed at temperatures as low as 4 K, especially for two types of cocaine. Well-resolved low-frequency absorption peaks were observed in the frequency range 0.1 - 3 THz with high resolution. Some of absorption peaks were found clearly to become more intense and shift to higher frequencies as the temperature was reduced. The results confirm that the low-frequency collective modes are highly sensitive to the structural and spatial arrangement of molecules. Furthermore, a number of common postal packaging materials made from paper, cardboard, even several types of plastic, have been tested with drug sample to assess the ability of THz-TDS in a hostile detection environment.

Differential distribution of voltage-gated channels in myelinated and unmyelinated baroreceptor afferents.

PubMed

Schild, John H; Kunze, Diana L

2012-12-24

Voltage gated ion channels (VGC) make possible the frequency coding of arterial pressure and the neurotransmission of this information along myelinated and unmyelinated fiber pathways. Although many of the same VGC isoforms are expressed in both fiber types, it is the relative expression of each that defines the unique discharge properties of myelinated A-type and unmyelinated C-type baroreceptors. For example, the fast inward Na⁺ current is a major determinant of the action potential threshold and the regenerative transmembrane current needed to sustain repetitive discharge. In A-type baroreceptors the TTX-sensitive Na(v)1.7 VGC contributes to the whole cell Na⁺ current. Na(v)1.7 is expressed at a lower density in C-type neurons and in conjunction with TTX-insensitive Na(v)1.8 and Na(v)1.9 VGC. As a result, action potentials of A-type neurons have firing thresholds that are 15-20 mV more negative and upstroke velocities that are 5-10 times faster than unmyelinated C-type neurons. A more depolarized threshold in conjunction with a broader complement of non-inactivating K(V) VGC subtypes produces C-type action potentials that are 3-4 times longer in duration than A-type neurons and at markedly lower levels of cell excitability. Unmyelinated baroreceptors also express KCa1.1 which provides approximately 25% of the total outward K⁺ current. KCa1.1 plays a critically important role in shaping the action potential profile of C-type neurons and strongly impacts neuronal excitability. A-type neurons do not functionally express the KCa1.1 channel despite having a whole cell Ca(V) current quite similar to that of C-type neurons. As a result, A-type neurons do not have the frequency-dependent braking forces of KCa1.1. Lack of a KCa current and only a limited complement of non-inactivating K(V) VGC in addition to a hyperpolarization activated HCN1 current that is nearly 10 times larger than in C-type neurons leads to elevated levels of discharge in A-type neurons, a hallmark of myelinated baroreceptors. Interestingly, HCN2 and HCN4 expression levels are comparable in both fiber types. Collectively, such apportion of VGC constrains the neural coding of myelinated A-type baroreceptors to low threshold, high frequency, high fidelity discharge but with a limited capacity for neuromodulation of afferent bandwidth. Unmyelinated C-type baroreceptors require greater depolarizing forces for spike initiation and have a low frequency discharge profile that is often poorly correlated with the physiological stimulus. But the complement of VGC in C-type neurons provides far greater capacity for neuromodulation of cell excitability than can be obtained from A-type baroreceptors. Copyright © 2012 Elsevier B.V. All rights reserved.

Higher-order vibrational mode frequency tuning utilizing fishbone-shaped microelectromechanical systems resonator

NASA Astrophysics Data System (ADS)

Suzuki, Naoya; Tanigawa, Hiroshi; Suzuki, Kenichiro

2013-04-01

Resonators based on microelectromechanical systems (MEMS) have received considerable attention for their applications for wireless equipment. The requirements for this application include small size, high frequency, wide bandwidth and high portability. However, few MEMS resonators with wide-frequency tuning have been reported. A fishbone-shaped resonator has a resonant frequency with a maximum response that can be changed according to the location and number of several exciting electrodes. Therefore, it can be expected to provide wide-frequency tuning. The resonator has three types of electrostatic forces that can be generated to deform a main beam. We evaluate the vibrational modes caused by each exciting electrodes by comparing simulated results with measured ones. We then successfully demonstrate the frequency tuning of the first to fifth resonant modes by using the algorithm we propose here. The resulting frequency tuning covers 178 to 1746 kHz. In addition, we investigate the suppression of the anchor loss to enhance the Q-factor. An experiment shows that tapered-shaped anchors provide a higher Q-factor than rectangular-shaped anchors. The Q-factor of the resonators supported by suspension beams is also discussed. Because the suspension beams cause complicated vibrational modes for higher frequencies, the enhancement of the Q-factor for high vibrational modes cannot be obtained here. At present, the tapered-anchor resonators are thought to be most suitable for frequency tuning applications.

High-resolution HLA haplotype frequencies of stem cell donors in Germany with foreign parentage: how can they be used to improve unrelated donor searches?

PubMed

Pingel, Julia; Solloch, Ute V; Hofmann, Jan A; Lange, Vinzenz; Ehninger, Gerhard; Schmidt, Alexander H

2013-03-01

In hematopoietic stem cell transplantation, human leukocyte antigens (HLA), usually HLA loci A, B, C, DRB1 and DQB1, are required to check histocompatibility between a potential donor and the recipient suffering from a malignant or non-malignant blood disease. As databases of potential unrelated donors are very heterogeneous with respect to typing resolution and number of typed loci, donor registries make use of haplotype frequency-based algorithms to provide matching probabilities for each potentially matching recipient/donor pair. However, it is well known that HLA allele and haplotype frequencies differ significantly between populations. We estimated high-resolution HLA-A, -B, -C, -DRB1 haplotype and allele frequencies of donors within DKMS German Bone Marrow Donor Center with parentage from 17 different countries: Turkey, Poland, Italy, Russian Federation, Croatia, Greece, Austria, Kazakhstan, France, The Netherlands, Republic of China, Romania, Portugal, USA, Spain, United Kingdom and Bosnia and Herzegovina. 5-locus haplotypes including HLA-DQB1 are presented for Turkey, Poland, Italy and Russian Federation. We calculated linkage disequilibria for each sample. Genetic distances between included countries could be shown to reflect geography. We further demonstrate how genetic differences between populations are reflected in matching probabilities of recipient/donor pairs and how they influence the search for unrelated donors as well as strategic donor center typings. Copyright © 2012 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

Micromachined PIN-PMN-PT Crystal Composite Transducer for High-Frequency Intravascular Ultrasound (IVUS) Imaging

PubMed Central

Li, Xiang; Ma, Teng; Tian, Jian; Han, Pengdi; Zhou, Qifa; Shung, K. Kirk

2015-01-01

In this paper, we report the use of micromachined PbIn1/2Nb1/2O3–PbMg1/3Nb2/3O3–PbTiO3 (PIN-PMN-PT) single crystal 1–3 composite material for intravascular ultrasound (IVUS) imaging application. The effective electromechanical coupling coefficient kt(eff) of the composite was measured to be 0.75 to 0.78. Acoustic impedance was estimated to be 20 MRayl. Based on the composite, needle-type and flexible-type IVUS transducers were fabricated. The composite transducer achieved an 86% bandwidth at the center frequency of 41 MHz, which resulted in a 43 μm axial resolution. Ex vivo IVUS imaging was conducted to demonstrate the improvement of axial resolution. The composite transducer was capable of identifying the three layers of a cadaver coronary artery specimen with high resolution. The PIN-PMN-PT-based composite has superior piezoelectric properties comparable to PMN-PT-based composite and its thermal stability is higher than PMN-PT. PIN-PMN-PT crystal can be an alternative approach for fabricating high-frequency composite, instead of using PMN-PT. PMID:24960706

Design and vibration control of vehicle engine mount activated by MR fluid and piezoelectric actuator

NASA Astrophysics Data System (ADS)

Lee, D. Y.; Park, Y. K.; Choi, S. B.; Lee, H. G.

2009-07-01

An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds (wide frequency range).

A New Catalogue of Fine Structures Superimposed on Solar Microwave Bursts

NASA Astrophysics Data System (ADS)

Fu, Qi-Jun; Yan, Yi-Hua; Liu, Yu-Ying; Wang, Min; Wang, Shu-Juan

2004-04-01

The 2.6--3.8 GHz, 4.5--7.5 GHz, 5.2--7.6 GHz and 0.7--1.5 GHz component spectrometers of Solar Broadband Radio Spectrometer (SBRS) started routine observations, respectively, in late August 1996, August 1999, August 1999, and June 2000. They just managed to catch the coming 23rd solar active maximum. Consequently, a large amount of microwave burst data with high temporal and high spectral resolutionand high sensitivity were obtained. A variety of fine structures (FS) superimposed on microwave bursts have been found. Some of them are known, such as microwave type III bursts, microwave spike emission, but these were observed with more detail; some are new. Reported for the first time here are microwave type U bursts with similar spectral morphology to those in decimetric and metric wavelengths, and with outstanding characteristics such as very short durations (tens to hundreds ms), narrow bandwidths, higher frequency drift rates and higher degrees of polarization. Type N and type M bursts were also observed. Detailed zebra pattern and fiber bursts at the high frequency were found. Drifting pulsation structure (DPS) phenomena closely associated with CME are considered to manifest the initial phase of the CME, and quasi-periodic pulsation with periods of tens ms have been recorded. Microwave ``patches", unlike those reported previously, were observed with very short durations (about 300 ms), very high flux densities (up to 1000 sfu), very high polarization (about 100% RCP), extremely narrow bandwidths (about 5%), and very high spectral indexes. These cannot be interpreted with the gyrosynchrotron process. A superfine structure in the form of microwave FS (ZPS, type U), consisting of microwave millisecond spike emission (MMS), was also found.

Laser-Bioplasma Interaction: The Blood Type Transmutation Induced by Multiple Ultrashort Wavelength Laser Beams

NASA Astrophysics Data System (ADS)

Stefan, V. Alexander

2015-11-01

The interaction of ultrashort wavelength multi laser beams with the flowing blood thin films leads to the transmutation of the blood types A, B, and AB into O type. This is a novel mechanism of importance for the transfusion medicine. Laser radiation is in resonance with the eigen-frequency modes of the antigen proteins and forces the proteins to parametrically oscillate until they get kicked out from the surface. The stripping away of antigens is done by the scanning-multiple-lasers of a high repetition rate in the blue-purple frequency domain. The guiding-lasers are in the red-green frequency domain. The laser force, (parametric interaction with the antigen eigen-oscillation), upon the antigen protein molecule must exceed its weight. The scanning laser beam is partially reflected as long as the antigen(s) is not eliminated. The process of the protein detachment can last a few minutes. Supported by Nikola Tesla Labs., Stefan University.

A SETI Search of Nearby Solar-Type Stars at the 203-GHz Positronium Hyperfine Resonance

NASA Technical Reports Server (NTRS)

Steffes, Paul G.; DeBoer, David R.

1994-01-01

The development of advanced millimeter-wave technology has made it possible to construct low-noise receivers and high-power transmitters comparable to those available at much lower frequencies. This technology, plus certain physical characteristics of the millimeter-wave spectrum, suggests possible advantages for use of this wavelength range for interstellar communications. As a result, a Search for ExtraTerrestrial Intelligence(SETI) type search has been conducted for narrow-bandwidth signals at frequencies near the positronium hyperfine spectral line (203.385 GHz), a potential natural reference frequency. A total of 40 solar-type stars within 23 parsecs were observed, in addition to three locations near the galactic center. No detections were made at the detection threshold of 2.3 x 10(exp -19) W/sq m in each of two orthogonal linear polarizations Future observations will be made with a higher resolution Fast Fourier Transform Spectrum Analyzer (FFTSA), which should improve sensitivity by an order of magnitude and reduce required observing time.

[Subclinical sensorineural hearing loss in female patients with rheumatoid arthritis].

PubMed

Treviño-González, José Luis; Villegas-González, Mario Jesús; Muñoz-Maldonado, Gerardo Enrique; Montero-Cantu, Carlos Alberto; Nava-Zavala, Arnulfo Hernán; Garza-Elizondo, Mario Alberto

2015-01-01

The rheumatoid arthritis is a clinical entity capable to cause hearing impairment that can be diagnosed promptly with high frequencies audiometry. To detect subclinical sensorineural hearing loss in patients with rheumatoid arthritis. Cross-sectional study on patients with rheumatoid arthritis performing high frequency audiometry 125Hz to 16,000Hz and tympanometry. The results were correlated with markers of disease activity and response to therapy. High frequency audiometry was performed in 117 female patients aged from 19 to 65 years. Sensorineural hearing loss was observed at a sensitivity of pure tones from 125 to 8,000 Hz in 43.59%, a tone threshold of 10,000 to 16,000Hz in 94.02% patients in the right ear and in 95.73% in the left ear. Hearing was normal in 8 (6.84%) patients. Hearing loss was observed in 109 (93.16%), and was asymmetric in 36 (30.77%), symmetric in 73 (62.37%), bilateral in 107 (91.45%), unilateral in 2 (1.71%), and no conduction and/or mixed hearing loss was encountered. Eight (6.83%) patients presented vertigo, 24 (20.51%) tinnitus. Tympanogram type A presented in 88.90% in the right ear and 91.46% in the left ear, with 5.98 to 10.25% type As. Stapedius reflex was present in 75.3 to 85.2%. Speech discrimination in the left ear was significantly different (p = 0.02)in the group older than 50 years. No association was found regarding markers of disease activity, but there was an association with the onset of rheumatoid arthritis disease. Patients with rheumatoid arthritis had a high prevalence of sensorineural hearing loss for high and very high frequencies. Copyright © 2015 Academia Mexicana de Cirugía A.C. Published by Masson Doyma México S.A. All rights reserved.

Analysis of Surface Water Pollution Accidents in China: Characteristics and Lessons for Risk Management

NASA Astrophysics Data System (ADS)

Yao, Hong; Zhang, Tongzhu; Liu, Bo; Lu, Feng; Fang, Shurong; You, Zhen

2016-04-01

Understanding historical accidents is important for accident prevention and risk mitigation; however, there are no public databases of pollution accidents in China, and no detailed information regarding such incidents is readily available. Thus, 653 representative cases of surface water pollution accidents in China were identified and described as a function of time, location, materials involved, origin, and causes. The severity and other features of the accidents, frequency and quantities of chemicals involved, frequency and number of people poisoned, frequency and number of people affected, frequency and time for which pollution lasted, and frequency and length of pollution zone were effectively used to value and estimate the accumulated probabilities. The probabilities of occurrences of various types based on origin and causes were also summarized based on these observations. The following conclusions can be drawn from these analyses: (1) There was a high proportion of accidents involving multi-district boundary regions and drinking water crises, indicating that more attention should be paid to environmental risk prevention and the mitigation of such incidents. (2) A high proportion of accidents originated from small-sized chemical plants, indicating that these types of enterprises should be considered during policy making. (3) The most common cause (49.8 % of the total) was intentional acts (illegal discharge); accordingly, efforts to increase environmental consciousness in China should be enhanced.

Analysis of Surface Water Pollution Accidents in China: Characteristics and Lessons for Risk Management.

PubMed

Yao, Hong; Zhang, Tongzhu; Liu, Bo; Lu, Feng; Fang, Shurong; You, Zhen

2016-04-01

Understanding historical accidents is important for accident prevention and risk mitigation; however, there are no public databases of pollution accidents in China, and no detailed information regarding such incidents is readily available. Thus, 653 representative cases of surface water pollution accidents in China were identified and described as a function of time, location, materials involved, origin, and causes. The severity and other features of the accidents, frequency and quantities of chemicals involved, frequency and number of people poisoned, frequency and number of people affected, frequency and time for which pollution lasted, and frequency and length of pollution zone were effectively used to value and estimate the accumulated probabilities. The probabilities of occurrences of various types based on origin and causes were also summarized based on these observations. The following conclusions can be drawn from these analyses: (1) There was a high proportion of accidents involving multi-district boundary regions and drinking water crises, indicating that more attention should be paid to environmental risk prevention and the mitigation of such incidents. (2) A high proportion of accidents originated from small-sized chemical plants, indicating that these types of enterprises should be considered during policy making. (3) The most common cause (49.8% of the total) was intentional acts (illegal discharge); accordingly, efforts to increase environmental consciousness in China should be enhanced.

21 CFR 884.4150 - Bipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2014 CFR

2014-04-01

... high frequency electrical current through tissue between two electrical contacts of a probe. This generic type of device may include the following accessories: an electrical generator, probes, and...

21 CFR 884.4150 - Bipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2012 CFR

2012-04-01

... high frequency electrical current through tissue between two electrical contacts of a probe. This generic type of device may include the following accessories: an electrical generator, probes, and...

21 CFR 884.4150 - Bipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2011 CFR

2011-04-01

... high frequency electrical current through tissue between two electrical contacts of a probe. This generic type of device may include the following accessories: an electrical generator, probes, and...

21 CFR 884.4150 - Bipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2013 CFR

2013-04-01

... high frequency electrical current through tissue between two electrical contacts of a probe. This generic type of device may include the following accessories: an electrical generator, probes, and...

Superburst oscillations: ocean and crustal modes excited by carbon-triggered type I X-ray bursts

NASA Astrophysics Data System (ADS)

Chambers, F. R. N.; Watts, A. L.; Cavecchi, Y.; Garcia, F.; Keek, L.

2018-07-01

Accreting neutron stars (NS) can exhibit high frequency modulations in their light curves during thermonuclear X-ray bursts, known as burst oscillations. The frequencies can be offset from the spin frequency of the NS by several Hz, and can drift by 1-3 Hz. One possible explanation is a mode in the bursting ocean, the frequency of which would decrease (in the rotating frame) as the burst cools, hence explaining the drifts. Most burst oscillations have been observed during the H/He-triggered bursts; however there has been one observation of oscillations during a superburst; hours long Type I X-ray bursts caused by unstable carbon burning deeper in the ocean. This paper calculates the frequency evolution of an oceanic r mode during a superburst. The rotating frame frequency varies during the burst from 4-14 Hz and is sensitive to the background parameters, in particular the temperature of the ocean and ignition depth. This calculation is compared to the superburst oscillations observed on 4U-1636-536. The predicted mode frequencies (˜10 Hz) would require a spin frequency of ˜592 Hz to match observations; 6 Hz higher than the spin inferred from an oceanic r-mode model for the H/He-triggered burst oscillations. This model also overpredicts the frequency drift during the superburst by 90 per cent.

Superburst oscillations: ocean and crustal modes excited by Carbon-triggered Type I X-ray bursts

NASA Astrophysics Data System (ADS)

Chambers, F. R. N.; Watts, A. L.; Cavecchi, Y.; Garcia, F.; Keek, L.

2018-04-01

Accreting neutron stars (NS) can exhibit high frequency modulations in their lightcurves during thermonuclear X-ray bursts, known as burst oscillations. The frequencies can be offset from the spin frequency of the NS by several Hz, and can drift by 1-3 Hz. One possible explanation is a mode in the bursting ocean, the frequency of which would decrease (in the rotating frame) as the burst cools, hence explaining the drifts. Most burst oscillations have been observed during H/He triggered bursts, however there has been one observation of oscillations during a superburst; hours' long Type I X-ray bursts caused by unstable carbon burning deeper in the ocean. This paper calculates the frequency evolution of an oceanic r-mode during a superburst. The rotating frame frequency varies during the burst from 4 - 14 Hz, and is sensitive to the background parameters, in particular the temperature of the ocean and ignition depth. This calculation is compared to the superburst oscillations observed on 4U-1636-536. The predicted mode frequencies (˜10 Hz) would require a spin frequency of ˜592 Hz to match observations; 6 Hz higher than the spin inferred from an oceanic r-mode model for the H/He triggered burst oscillations. This model also over-predicts the frequency drift during the superburst by 90%.

Tracking of an electron beam through the solar corona with LOFAR

NASA Astrophysics Data System (ADS)

Mann, G.; Breitling, F.; Vocks, C.; Aurass, H.; Steinmetz, M.; Strassmeier, K. G.; Bisi, M. M.; Fallows, R. A.; Gallagher, P.; Kerdraon, A.; Mackinnon, A.; Magdalenic, J.; Rucker, H.; Anderson, J.; Asgekar, A.; Avruch, I. M.; Bell, M. E.; Bentum, M. J.; Bernardi, G.; Best, P.; Bîrzan, L.; Bonafede, A.; Broderick, J. W.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Corstanje, A.; Gasperin, F. de; Geus, E. de; Deller, A.; Duscha, S.; Eislöffel, J.; Engels, D.; Falcke, H.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Gunst, A. W.; van Haarlem, M.; Hassall, T. E.; Heald, G.; Hessels, J. W. T.; Hoeft, M.; Hörandel, J.; Horneffer, A.; Juette, E.; Karastergiou, A.; Klijn, W. F. A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; Maat, P.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; McKean, J. P.; Mulcahy, D. D.; Munk, H.; Nelles, A.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pizzo, R.; Polatidis, A. G.; Rafferty, D.; Reich, W.; Röttgering, H.; Scaife, A. M. M.; Schwarz, D. J.; Serylak, M.; Sluman, J.; Smirnov, O.; Stappers, B. W.; Tagger, M.; Tang, Y.; Tasse, C.; ter Veen, S.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; van Weeren, R. J.; Wise, M. W.; Wucknitz, O.; Yatawatta, S.; Zarka, P.; Zensus, J. A.

2018-03-01

The Sun's activity leads to bursts of radio emission, among other phenomena. An example is type-III radio bursts. They occur frequently and appear as short-lived structures rapidly drifting from high to low frequencies in dynamic radio spectra. They are usually interpreted as signatures of beams of energetic electrons propagating along coronal magnetic field lines. Here we present novel interferometric LOFAR (LOw Frequency ARray) observations of three solar type-III radio bursts and their reverse bursts with high spectral, spatial, and temporal resolution. They are consistent with a propagation of the radio sources along the coronal magnetic field lines with nonuniform speed. Hence, the type-III radio bursts cannot be generated by a monoenergetic electron beam, but by an ensemble of energetic electrons with a spread distribution in velocity and energy. Additionally, the density profile along the propagation path is derived in the corona. It agrees well with three-fold coronal density model by (1961, ApJ, 133, 983).

Frequency, character and predisposing factor of headache among students of medical college of Karachi.

PubMed

Noor, Tooba; Sajjad, Ali; Asma, Anoosha

2016-02-01

To evaluate the frequency, predisposing factors and symptomatology of headache among medical students. The cross-sectional study was conducted from September to December 2013 and comprised students of two medical colleges of Karachi. International Classification of Headache Disorder-II criterion was used to diagnose and classify headache. SPSS 17 was used for statistical analysis. Of the 413 medical students studies, 326(79%) had tension type headache, and 87 (21%) had migraine. Headache was more frequent among females than males, with a ratio of 6.5:1. Both types of headache were significantly associated with self-reported disturbed sleep pattern, stress and various triggering factors (p<0.05 each). Both types greatly influenced individual's daily life with significant association with avoiding academics, extra-curricular activities, family and friends (p<0.05 each). High self-medication rate of 400(96.9%) was observed. The prevalence of headache among medical students was high with female predominance. Infrequent consultation needs to be addressed through awareness programmes.

Ultra-high-frequency chaos in a time-delay electronic device with band-limited feedback.

PubMed

Illing, Lucas; Gauthier, Daniel J

2006-09-01

We report an experimental study of ultra-high-frequency chaotic dynamics generated in a delay-dynamical electronic device. It consists of a transistor-based nonlinearity, commercially-available amplifiers, and a transmission-line for feedback. The feedback is band-limited, allowing tuning of the characteristic time-scales of both the periodic and high-dimensional chaotic oscillations that can be generated with the device. As an example, periodic oscillations ranging from 48 to 913 MHz are demonstrated. We develop a model and use it to compare the experimentally observed Hopf bifurcation of the steady-state to existing theory [Illing and Gauthier, Physica D 210, 180 (2005)]. We find good quantitative agreement of the predicted and the measured bifurcation threshold, bifurcation type and oscillation frequency. Numerical integration of the model yields quasiperiodic and high dimensional chaotic solutions (Lyapunov dimension approximately 13), which match qualitatively the observed device dynamics.

Photovoltage detection of edge magnetoplasmon oscillations and giant magnetoplasmon resonances in a two-dimensional hole system

NASA Astrophysics Data System (ADS)

Mi, Jian; Wang, Jianli; Pfeiffer, Loren N.; West, Ken W.; Baldwin, Kirk W.; Zhang, Chi

In our high mobility p-type AlGaAs/GaAs two-dimensional hole samples, we originally observe the B - periodic oscillation induced by microwave (MW) in photovoltage (PV) measurements. In the frequency range of our measurements (5 - 40 GHz), the period is inversely proportional to the microwave frequency (f). The distinct oscillations come from the edge magnetoplasmon (EMP) in the high quality heavy hole system. Simultaneously, we observe the giant plasmon resonance signals in our measurements on the shallow two-dimensional hole system (2DHS).

Blind identification of image manipulation type using mixed statistical moments

NASA Astrophysics Data System (ADS)

Jeong, Bo Gyu; Moon, Yong Ho; Eom, Il Kyu

2015-01-01

We present a blind identification of image manipulation types such as blurring, scaling, sharpening, and histogram equalization. Motivated by the fact that image manipulations can change the frequency characteristics of an image, we introduce three types of feature vectors composed of statistical moments. The proposed statistical moments are generated from separated wavelet histograms, the characteristic functions of the wavelet variance, and the characteristic functions of the spatial image. Our method can solve the n-class classification problem. Through experimental simulations, we demonstrate that our proposed method can achieve high performance in manipulation type detection. The average rate of the correctly identified manipulation types is as high as 99.22%, using 10,800 test images and six manipulation types including the authentic image.

A pilot study showing associations between frequency of CD4(+) memory cell subsets at diagnosis and duration of partial remission in type 1 diabetes.

PubMed

Moya, Rosita; Robertson, Hannah Kathryn; Payne, Dawson; Narsale, Aditi; Koziol, Jim; Davies, Joanna Davida

2016-05-01

In some patients with type 1 diabetes the dose of insulin required to achieve euglycemia is substantially reduced soon after diagnosis. This partial remission is associated with β-cell function and good glucose control. The purpose of this study was to assess whether frequencies of CD4(+) T cell subsets in children newly diagnosed with type 1 diabetes are associated with length of partial remission. We found that the frequency of CD4(+) memory cells, activated Treg cells and CD25(+) cells that express a high density of the IL-7 receptor, CD127 (CD127(hi)) are strongly associated with length of partial remission. Prediction of length of remission via Cox regression is significantly enhanced when CD25(+) CD127(hi) cell frequency is combined with either Insulin Dependent Adjusted A1c (IDAA1c), or glycosylated hemoglobin (HbA1c), or C-peptide levels at diagnosis. CD25(+) CD127(hi) cells do not express Foxp3, LAG-3 and CD49b, indicating that they are neither Treg nor Tr1 cells. Copyright © 2016 Elsevier Inc. All rights reserved.

Are all types of expertise created equal? Car experts use different spatial frequency scales for subordinate categorization of cars and faces.

PubMed

Harel, Assaf; Bentin, Shlomo

2013-01-01

A much-debated question in object recognition is whether expertise for faces and expertise for non-face objects utilize common perceptual information. We investigated this issue by assessing the diagnostic information required for different types of expertise. Specifically, we asked whether face categorization and expert car categorization at the subordinate level relies on the same spatial frequency (SF) scales. Fifteen car experts and fifteen novices performed a category verification task with spatially filtered images of faces, cars, and airplanes. Images were categorized based on their basic (e.g. "car") and subordinate level (e.g. "Japanese car") identity. The effect of expertise was not evident when objects were categorized at the basic level. However, when the car experts categorized faces and cars at the subordinate level, the two types of expertise required different kinds of SF information. Subordinate categorization of faces relied on low SFs more than on high SFs, whereas subordinate expert car categorization relied on high SFs more than on low SFs. These findings suggest that expertise in the recognition of objects and faces do not utilize the same type of information. Rather, different types of expertise require different types of diagnostic visual information.

Frequency of twelve carcinogenic human papilloma virus types among women from the South Backa region, Vojvodina, Serbia.

PubMed

Kovacevic, Gordana; Nikolic, Natasa; Jovanovic-Galovic, Aleksandra; Hrnjakovic-Cvjetkovic, Iv; Vuleta, Dusan; Patic, Aleksandra; Radovanov, Jelena; Milosevic, Vesna

2016-01-05

The aim of this study was to determine the presence and age distribution of different oncogenic human papilloma virus (HPV) types in women in the South Backa region and its relationship to Pap results. In a group of 1087 women with normal and abnormal cytology, the commercial HR HPV Real-TM kit (Sacace Biotechnologies, Italy) was used. Overall, 50.5% of the women were HPV positive. The presence of HPV types 18, 31, 51, and 58 was significantly influenced by age, while the presence of HPV types 16 and 45 was significantly influenced by cervical cytology. Results of the LSD test show a wide spectrum of high risk HPV among women with normal cytology and women with a low grade cervical lesion rate (atypical squamous cell of undetermined significance (ASCUS) and low grade squamous intraepithelial lesions (LSIL). The most prevalent HPV types found were 16, 31, 51, 18, and 52. In the HSIL group the most prevalent HPV types were 16 and 45. The reported results provide new data on the circulation of oncogenic HPV genotypes and frequency of multiple infections among women in Vojvodina and suggest that a prophylactic vaccine against HPV 16 and 18 has the potential to prevent approximately half of the high-grade lesions.

Are All Types of Expertise Created Equal? Car Experts Use Different Spatial Frequency Scales for Subordinate Categorization of Cars and Faces

PubMed Central

Harel, Assaf; Bentin, Shlomo

2013-01-01

A much-debated question in object recognition is whether expertise for faces and expertise for non-face objects utilize common perceptual information. We investigated this issue by assessing the diagnostic information required for different types of expertise. Specifically, we asked whether face categorization and expert car categorization at the subordinate level relies on the same spatial frequency (SF) scales. Fifteen car experts and fifteen novices performed a category verification task with spatially filtered images of faces, cars, and airplanes. Images were categorized based on their basic (e.g. “car”) and subordinate level (e.g. “Japanese car”) identity. The effect of expertise was not evident when objects were categorized at the basic level. However, when the car experts categorized faces and cars at the subordinate level, the two types of expertise required different kinds of SF information. Subordinate categorization of faces relied on low SFs more than on high SFs, whereas subordinate expert car categorization relied on high SFs more than on low SFs. These findings suggest that expertise in the recognition of objects and faces do not utilize the same type of information. Rather, different types of expertise require different types of diagnostic visual information. PMID:23826188

The Effect of Adaptive Nonlinear Frequency Compression on Phoneme Perception.

PubMed

Glista, Danielle; Hawkins, Marianne; Bohnert, Andrea; Rehmann, Julia; Wolfe, Jace; Scollie, Susan

2017-12-12

This study implemented a fitting method, developed for use with frequency lowering hearing aids, across multiple testing sites, participants, and hearing aid conditions to evaluate speech perception with a novel type of frequency lowering. A total of 8 participants, including children and young adults, participated in real-world hearing aid trials. A blinded crossover design, including posttrial withdrawal testing, was used to assess aided phoneme perception. The hearing aid conditions included adaptive nonlinear frequency compression (NFC), static NFC, and conventional processing. Enabling either adaptive NFC or static NFC improved group-level detection and recognition results for some high-frequency phonemes, when compared with conventional processing. Mean results for the distinction component of the Phoneme Perception Test (Schmitt, Winkler, Boretzki, & Holube, 2016) were similar to those obtained with conventional processing. Findings suggest that both types of NFC tested in this study provided a similar amount of speech perception benefit, when compared with group-level performance with conventional hearing aid technology. Individual-level results are presented with discussion around patterns of results that differ from the group average.

A novel power-efficient high-speed clock management unit using quantum-dot cellular automata

NASA Astrophysics Data System (ADS)

Abutaleb, M. M.

2017-04-01

Quantum-dot cellular automata (QCA) is one of the most attractive alternatives for complementary metal-oxide semiconductor technology. The QCA widely supports a new paradigm in the field of nanotechnology that has the potential for high density, low power, and high speed. The clock manager is an essential building block in the new microwave and radio frequency integrated circuits. This paper describes a novel QCA-based clock management unit (CMU) that provides innovative clocking capabilities. The proposed CMU is achieved by utilizing edge-triggered D-type flip-flops (D-FFs) in the design of frequency synthesizer and phase splitter. Edge-triggered D-FF structures proposed in this paper have the successful QCA implementation and simulation with the least complexity and power dissipation as compared to earlier structures. The frequency synthesizer is used to generate new clock frequencies from the reference clock frequency based on a combination of power-of-two frequency dividers. The phase splitter is integrated with the frequency synthesizer to generate four clock signals that are 90o out of phase with each other. This paper demonstrates that the proposed QCA CMU structure has a superior performance. Furthermore, the proposed CMU is straightforwardly scalable due to the use of modular component architecture.

Caller sex and orientation influence spectral characteristics of "two-voice" stereotyped calls produced by free-ranging killer whales.

PubMed

Miller, Patrick J O; Samarra, Filipa I P; Perthuison, Aurélie D

2007-06-01

This study investigates how particular received spectral characteristics of stereotyped calls of sexually dimorphic adult killer whales may be influenced by caller sex, orientation, and range. Calls were ascribed to individuals during natural behavior using a towed beamforming array. The fundamental frequency of both high-frequency and low-frequency components did not differ consistently by sex. The ratio of peak energy within the fundamental of the high-frequency component relative to summed peak energy in the first two low-frequency component harmonics, and the number of modulation bands off the high-frequency component, were significantly greater when whales were oriented towards the array, while range and adult sex had little effect. In contrast, the ratio of peak energy in the first versus second harmonics of the low-frequency component was greater in calls produced by adult females than adult males, while orientation and range had little effect. The dispersion of energy across harmonics has been shown to relate to body size or sex in terrestrial species, but pressure effects during diving are thought to make such a signal unreliable in diving animals. The observed spectral differences by signaler sex and orientation suggest that these types of information may be transmitted acoustically by freely diving killer whales.

CARBON-TO-OXYGEN RATIOS IN M DWARFS AND SOLAR-TYPE STARS

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

Nakajima, Tadashi; Sorahana, Satoko, E-mail: tadashi.nakajima@nao.ac.jp, E-mail: sorahana@astron.s.u-tokyo.ac.jp

It has been suggested that high C/O ratios (>0.8) in circumstellar disks lead to the formation of carbon-dominated planets. Based on the expectation that elemental abundances in the stellar photospheres give the initial abundances in the circumstellar disks, the frequency distributions of C/O ratios of solar-type stars have been obtained by several groups. The results of these investigations are mixed. Some find C/O > 0.8 in more than 20% of stars, and C/O > 1.0 in more than 6%. Others find C/O > 0.8 in none of the sample stars. These works on solar-type stars are all differential abundance analysesmore » with respect to the Sun and depend on the adopted C/O ratio in the Sun. Recently, a method of molecular line spectroscopy of M dwarfs, in which carbon and oxygen abundances are derived respectively from CO and H{sub 2}O lines in the K band, has been developed. The resolution of the K- band spectrum is 20,000. Carbon and oxygen abundances of 46 M dwarfs have been obtained by this nondifferential abundance analysis. Carbon-to-oxygen ratios in M dwarfs derived by this method are more robust than those in solar-type stars derived from neutral carbon and oxygen lines in the visible spectra because of the difficulty in the treatment of oxygen lines. We have compared the frequency distribution of C/O distributions in M dwarfs with those of solar-type stars and have found that the low frequency of high-C/O ratios is preferred.« less

Flexibility of space structures makes design shaky

NASA Technical Reports Server (NTRS)

Hearth, D. P.; Boyer, W. J.

1985-01-01

An evaluation is made of the development status of high stiffness space structures suitable for orbital construction or deployment of large diameter reflector antennas, with attention to the control system capabilities required by prospective space structure system types. The very low structural frequencies typical of very large, radio frequency antenna structures would be especially difficult for a control system to counteract. Vibration control difficulties extend across the frequency spectrum, even to optical and IR reflector systems. Current research and development efforts are characterized with respect to goals and prospects for success.

Determining the prevalence of SCCmec polymorphism, virulence and antibiotic resistance genes among methicillin-resistant Staphylococcus aureus (MRSA) isolates collected from selected hospitals in west of Iran.

PubMed

Taherikalani, Morovat; Mohammadzad, Mohammad Reza; Soroush, Setareh; Maleki, Mohammad Hossein; Azizi-Jalilian, Farid; Pakzad, Iraj; Sadeghifard, Nourkhoda; Asadollahi, Parisa; Emaneini, Mohammad; Monjezi, Aazam; Alikhani, Mohammad Yousef

2016-04-01

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important pathogens worldwide and compared to other staphylococcal species that are associated with higher mortality rate. A total of 500 Staphylococcus spp. was collected from selected hospitals in Ilam, Kermanshah, Khorram Abad and Hamadan cities and, via phenotypic and genotypic methods, was assessed to find MRSA. The presence or absence of prevalent antibiotic resistance genes and virulence genes was evaluated among MRSA isolates, using polymerase chain reaction (PCR) method, and then the SCCmec typing of these isolates was assayed by multiplex PCR. A total of 372 (74.4%) Stapylococcus spp. isolates were identified as S. aureus, among which 200 (53.8%) possessed the mecA gene and were distinguished as MRSA. All of MRSA isolates contained blaZ gene. The frequency of ermA and ermC genes among erythromycin-resistant MRSA isolates was 21.6% and 66.7%, respectively. The frequency of the virulence genes eta, hla and sea among MRSA isolates was 10%, 80.5% and 100%, respectively. SCCmec type IV accounted for 30.6% of the MRSA isolates and SCCmec type III, SCCmec type II and SCCmec type I accounted for 30%, 22% and 17.5% of the isolates, respectively. The antibiotic resistance genes and the virulence genes of blaZ, hla, sea, eta and ermC had high frequencies among the MRSA isolates. This study showed that the antibiotic resistance genes had higher frequencies among SCCmec types I and IV, which confirms the previous reports in this field.

Development of a simple MR-compatible vibrotactile stimulator using a planar-coil-type actuator.

PubMed

Kim, Hyung-Sik; Choi, Mi-Hyun; Chung, Yoon-Gi; Kim, Sung-Phil; Jun, Jae-Hoon; Park, Jang-Yeon; Yi, Jeong-Han; Park, Jong-Rak; Lim, Dae-Woon; Chung, Soon-Cheol

2013-06-01

For this study, we developed a magnetic resonance (MR)-compatible vibrotactile stimulator using a planar-coil-type actuator. The newly developed vibrotactile stimulator consists of three units: control unit, drive unit, and planar-coil-type actuator. The control unit controls frequency, intensity, time, and channel, and transfers the stimulation signals to the drive unit. The drive unit operates the planar-coil-type actuator in response to commands from the control unit. The planar-coil-type actuator, which uses a planar coil instead of conventional electric wire, generates vibrating stimulation through interaction of the current of the planar coil with the static magnetic field of the MR scanner. Even though the developed tactile stimulating system is small, simple, and inexpensive, it has a wide range of stimulation frequencies (20 ~ 400 Hz, at 40 levels) and stimulation intensities (0 ~ 7 V, at 256 levels). The stimulation intensity does not change due to frequency changes. Since the transient response time is a few microseconds, the stimulation time can be controlled on a scale of microseconds. In addition, this actuator has the advantages of providing highly repeatable stimulation, being durable, being able to assume various shapes, and having an adjustable contact area with the skin. The new stimulator operated stably in an MR environment without affecting the MR images. Using functional magnetic resonance imaging, we observed the brain activation changes resulting from stimulation frequency and intensity changes.

Contribution of low-frequency harmonics to Mandarin Chinese tone identification in quiet and six-talker babble background.

PubMed

Liu, Chang; Azimi, Behnam; Bhandary, Moulesh; Hu, Yi

2014-01-01

The goal of this study was to investigate Mandarin Chinese tone identification in quiet and multi-talker babble conditions for normal-hearing listeners. Tone identification was measured with speech stimuli and stimuli with low and/or high harmonics that were embedded in three Mandarin vowels with two fundamental frequencies. There were six types of stimuli: all harmonics (All), low harmonics (Low), high harmonics (High), and the first (H1), second (H2), and third (H3) harmonic. Results showed that, for quiet conditions, individual harmonics carried frequency contour information well enough for tone identification with high accuracy; however, in noisy conditions, tone identification with individual low harmonics (e.g., H1, H2, and H3) was significantly lower than that with the Low, High, and All harmonics. Moreover, tone identification with individual harmonics in noise was lower for a low F0 than for a high F0, and was also dependent on vowel category. Tone identification with individual low-frequency harmonics was accounted for by local signal-to-noise ratios, indicating that audibility of harmonics in noise may play a primary role in tone identification.

Your attention please: increasing ambient noise levels elicits a change in communication behaviour in humpback whales (Megaptera novaeangliae)

PubMed Central

Dunlop, Rebecca A.; Cato, Douglas H.; Noad, Michael J.

2010-01-01

High background noise is an important obstacle in successful signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify their acoustic signal by increasing the repetition rate, duration, amplitude or frequency range of the signal. An alternative method to ensure successful signal reception, yet to be tested in animals, involves the use of two different types of signal, where one signal type may enhance the other in periods of high background noise. Humpback whale communication signals comprise two different types: vocal signals, and surface-generated signals such as ‘breaching’ or ‘pectoral slapping’. We found that humpback whales gradually switched from primarily vocal to primarily surface-generated communication in increasing wind speeds and background noise levels, though kept both signal types in their repertoire. Vocal signals have the advantage of having higher information content but may have the disadvantage of loosing this information in a noisy environment. Surface-generated sounds have energy distributed over a greater frequency range and may be less likely to become confused in periods of high wind-generated noise but have less information content when compared with vocal sounds. Therefore, surface-generated sounds may improve detection or enhance the perception of vocal signals in a noisy environment. PMID:20392731

Your attention please: increasing ambient noise levels elicits a change in communication behaviour in humpback whales (Megaptera novaeangliae).

PubMed

Dunlop, Rebecca A; Cato, Douglas H; Noad, Michael J

2010-08-22

High background noise is an important obstacle in successful signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify their acoustic signal by increasing the repetition rate, duration, amplitude or frequency range of the signal. An alternative method to ensure successful signal reception, yet to be tested in animals, involves the use of two different types of signal, where one signal type may enhance the other in periods of high background noise. Humpback whale communication signals comprise two different types: vocal signals, and surface-generated signals such as 'breaching' or 'pectoral slapping'. We found that humpback whales gradually switched from primarily vocal to primarily surface-generated communication in increasing wind speeds and background noise levels, though kept both signal types in their repertoire. Vocal signals have the advantage of having higher information content but may have the disadvantage of loosing this information in a noisy environment. Surface-generated sounds have energy distributed over a greater frequency range and may be less likely to become confused in periods of high wind-generated noise but have less information content when compared with vocal sounds. Therefore, surface-generated sounds may improve detection or enhance the perception of vocal signals in a noisy environment.

Effects of different frequencies of transcutaneous electrical nerve stimulation on venous vascular reactivity

PubMed Central

Franco, O.S.; Paulitsch, F.S.; Pereira, A.P.C.; Teixeira, A.O.; Martins, C.N.; Silva, A.M.V.; Plentz, R.D.M.; Irigoyen, M.C.; Signori, L.U.

2014-01-01

Transcutaneous electrical nerve stimulation (TENS) is a type of therapy used primarily for analgesia, but also presents changes in the cardiovascular system responses; its effects are dependent upon application parameters. Alterations to the cardiovascular system suggest that TENS may modify venous vascular response. The objective of this study was to evaluate the effects of TENS at different frequencies (10 and 100 Hz) on venous vascular reactivity in healthy subjects. Twenty-nine healthy male volunteers were randomized into three groups: placebo (n=10), low-frequency TENS (10 Hz, n=9) and high-frequency TENS (100 Hz, n=10). TENS was applied for 30 min in the nervous plexus trajectory from the superior member (from cervical to dorsal region of the fist) at low (10 Hz/200 μs) and high frequency (100 Hz/200 μs) with its intensity adjusted below the motor threshold and intensified every 5 min, intending to avoid accommodation. Venous vascular reactivity in response to phenylephrine, acetylcholine (endothelium-dependent) and sodium nitroprusside (endothelium-independent) was assessed by the dorsal hand vein technique. The phenylephrine effective dose to achieve 70% vasoconstriction was reduced 53% (P<0.01) using low-frequency TENS (10 Hz), while in high-frequency stimulation (100 Hz), a 47% increased dose was needed (P<0.01). The endothelium-dependent (acetylcholine) and independent (sodium nitroprusside) responses were not modified by TENS, which modifies venous responsiveness, and increases the low-frequency sensitivity of α1-adrenergic receptors and shows high-frequency opposite effects. These changes represent an important vascular effect caused by TENS with implications for hemodynamics, inflammation and analgesia. PMID:24820225

Dual-frequency transducer with a wideband PVDF receiver for contrast-enhanced, adjustable harmonic imaging

NASA Astrophysics Data System (ADS)

Kim, Jinwook; Lindsey, Brooks D.; Li, Sibo; Dayton, Paul A.; Jiang, Xiaoning

2017-04-01

Acoustic angiography is a contrast-enhanced, superharmonic microvascular imaging method. It has shown the capability of high-resolution and high-contrast-to-tissue-ratio (CTR) imaging for vascular structure near tumor. Dual-frequency ultrasound transducers and arrays are usually used for this new imaging technique. Stacked-type dual-frequency transducers have been developed for this vascular imaging method by exciting injected microbubble contrast agent (MCA) in the vessels with low-frequency (1-5 MHz), moderate power ultrasound burst waves and receiving the superharmonic responses from MCA by a high-frequency receiver (>10 MHz). The main challenge of the conventional dual-frequency transducers is a limited penetration depth (<25 mm) due to the insufficient receiving sensitivity for highfrequency harmonic signal detection. A receiver with a high receiving sensitivity spanning a wide superharmonic frequency range (3rd to 6th) enables selectable bubble harmonic detection considering the required penetration depth. Here, we develop a new dual-frequency transducer composed of a 2 MHz 1-3 composite transmitter and a polyvinylidene fluoride (PVDF) receiver with a receiving frequency range of 4-12 MHz for adjustable harmonic imaging. The developed transducer was tested for harmonic responses from a microbubble-injected vessel-mimicking tube positioned 45 mm away. Despite the long imaging distance (45 mm), the prototype transducer detected clear harmonic response with the contrast-to-noise ratio of 6-20 dB and the -6 dB axial resolution of 200-350 μm for imaging a 200 um-diameter cellulose tube filled with microbubbles.

Electromyographic activity of strap and cricothyroid muscles in pitch change.

PubMed

Roubeau, B; Chevrie-Muller, C; Lacau Saint Guily, J

1997-05-01

The EMG activity of the cricothyroid muscle (CT) and the three extrinsic laryngeal muscles (thyohyoid, TH; sternothyroid, ST, and sternohyoid, SH) were recorded throughout the voice range of one female and one male subject, both untrained singers. The voice range was examined using rising and falling glissandos (production of a sustained sound with progressive and continuous variation of fundamental frequency). Muscle activity was observed at various pitches during the glissandos. The strap muscle activity during the production of glissandos appears to be synergistic. At the lowest frequency, the CT is inactive but strap muscles (TH, ST, SH) are active. As frequency increases, strap muscle activity decreases while the CT controls frequency in the middle of the range. At higher frequencies the strap muscles once again become active. This activity might depend on the vocal vibratory mechanism involved. The role of the strap muscles at high pitches is a widely debated point but it seems that in some way they control the phenomena relevant to the rising pitch. The phasic-type strap muscle activity contrasts with the tonic-type activity of the CT. The CT closely controls the frequency, while the straps are not directly linked to the pitch but rather to the evolution of the frequency of voice production (speaking voice, singing voice, held notes, glissandos, trillo, vibrato, etc.).

Emotional and Behavioural Problems in Children with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Maskey, Morag; Warnell, Frances; Parr, Jeremy R.; Le Couteur, Ann; McConachie, Helen

2013-01-01

The type, frequency and inter-relationships of emotional and behavioural problems in 863 children with autism spectrum disorder (ASD) were investigated using the population-based Database of children with ASD living in the North East of England (Daslne). A high rate of problems was reported, with 53% of children having 4 or more types of problems…

Relationship between frequency of hypoglycemic episodes and changes in carotid atherosclerosis in insulin-treated patients with type 2 diabetes mellitus.

PubMed

Mita, Tomoya; Katakami, Naoto; Shiraiwa, Toshihiko; Yoshii, Hidenori; Kuribayashi, Nobuichi; Osonoi, Takeshi; Kaneto, Hideaki; Kosugi, Keisuke; Umayahara, Yutaka; Gosho, Masahiko; Shimomura, Iichiro; Watada, Hirotaka

2017-01-09

The effect of hypoglycemia on the progression of atherosclerosis in patients with type 2 diabetes mellitus (T2DM) remains largely unknown. This is a post hoc analysis of a randomized trial to investigate the relationship between hypoglycemic episodes and changes in carotid intima-media thickness (IMT). Among 274 study subjects, 104 patients experienced hypoglycemic episodes. Increases in the mean IMT and left maximum IMT of the common carotid arteries (CCA) were significantly greater in patients with hypoglycemia compared to those without hypoglycemia. Classification of the patients into three groups according to the frequency of hypoglycemic episodes showed that high frequency of hypoglycemic events was associated with increases in mean IMT-CCA, and left max-IMT-CCA and right max-IMT-CCA. In addition, repetitive episodes of hypoglycemia were associated with a reduction in the beneficial effects of sitagliptin on carotid IMT. Our data suggest that frequency of hypoglycemic episodes was associated with changes in carotid atherosclerosis.

Fast physical-random number generation using laser diode's frequency noise: influence of frequency discriminator

NASA Astrophysics Data System (ADS)

Matsumoto, Kouhei; Kasuya, Yuki; Yumoto, Mitsuki; Arai, Hideaki; Sato, Takashi; Sakamoto, Shuichi; Ohkawa, Masashi; Ohdaira, Yasuo

2018-02-01

Not so long ago, pseudo random numbers generated by numerical formulae were considered to be adequate for encrypting important data-files, because of the time needed to decode them. With today's ultra high-speed processors, however, this is no longer true. So, in order to thwart ever-more advanced attempts to breach our system's protections, cryptologists have devised a method that is considered to be virtually impossible to decode, and uses what is a limitless number of physical random numbers. This research describes a method, whereby laser diode's frequency noise generate a large quantities of physical random numbers. Using two types of photo detectors (APD and PIN-PD), we tested the abilities of two types of lasers (FP-LD and VCSEL) to generate random numbers. In all instances, an etalon served as frequency discriminator, the examination pass rates were determined using NIST FIPS140-2 test at each bit, and the Random Number Generation (RNG) speed was noted.

The link between competitive sports and gambling behaviors among youths.

PubMed

Gavriel-Fried, Belle; Bronstein, Israel; Sherpsky, Idit

2015-04-01

This study examines the association between physical activities and gambling, making a distinction between two characteristics of the former: intensity level and type (competitive/non-competitive). 316 adolescents from four high schools in Israel completed questionnaires. For males, participation in competitive athletic sports was associated with gambling frequency and problem gambling. For females, participation in competitive athletic sports was associated only with gambling frequency. Both types of physical activity and gender are important when analyzing the association between gambling and sporting activities. Youths involved in competitive sports are at greater risk for gambling involvement. (Am J Addict 2015;24:200-202). © American Academy of Addiction Psychiatry.

Note: Force- and torque-detection of high frequency electron spin resonance using a membrane-type surface-stress sensor

NASA Astrophysics Data System (ADS)

Takahashi, Hideyuki; Ishimura, Kento; Okamoto, Tsubasa; Ohmichi, Eiji; Ohta, Hitoshi

2018-03-01

We developed a practical useful method for force- and torque-detected electron spin resonance (FDESR/TDESR) spectroscopy in the millimeter wave frequency region. This method uses a commercially available membrane-type surface-stress (MSS) sensor. The MSS is composed of a silicon membrane supported by four beams in which piezoresistive paths are integrated for detecting the deformation of the membrane. Although this device has a lower spin sensitivity than a microcantilever, it offers several distinct advantages, including mechanical strength, ease of use, and versatility. These advantages make this device suitable for practical applications that require FDESR/TDESR.

[Frequencies of blood groups, ABO and Rh D incompatibility in post-delivery women and their liveborn].

PubMed

Baiochi, Eduardo; Camano, Luiz; Sass, Nelson; Colas, Osmar Ribeiro

2007-01-01

This study aimed to assess the frequency of different blood phenotypes and to predict the risk of Rh D alloimmunization and maternal-fetal incompatibility in a Brazilian population living in the West zone of the city of São Paulo-Brazil. This descriptive study evaluated 2,372 post-delivery women and their liveborn during one year. Blood types were analyzed by means of tube agglutination tests. The blood type frequencies were: 50.67 O, 32.17 A, 13.45 B, 3.75 AB, 90.34 Rh D(+) and 9.66 Rh D(-). ABO maternal-fetal incompatibility was detected in 18.4% and Rh D incompatibility in 7%. The fraction of Rh D(-) population at high risk for Rh D alloimmunization was 82%, emphasizing the importance of Rh D alloimmunization profilaxis.

Retrieval of methanol absorption parameters at terahertz frequencies using multispectral fitting

NASA Astrophysics Data System (ADS)

Slocum, David M.; Xu, Li-Hong; Giles, Robert H.; Goyette, Thomas M.

2015-12-01

A high-resolution broadband study of the methanol absorption spectrum was performed at 1.480-1.495 THz. The transmittance was recorded under both self- and air-broadening conditions for multiple pressures at a resolution of 500 kHz. A multispectral fitting analysis was then performed. The transition frequency, absolute intensity, self- and air-broadening coefficients, and self- and air-induced pressure shifts were retrieved for 221 absorption lines using the multispectral fitting routine. Observed in the data were two different series of transitions, both a b-type Q-branch with K = - 7 ← - 6 and an a-type R-branch with J = 31 ← 30 . The retrieved frequency position values were compared with values from spectral databases and trends within the different series were identified. An analysis of the precision of the fitting routine was also performed.

Simulation of precipitation by weather pattern and frontal analysis

NASA Astrophysics Data System (ADS)

Wilby, Robert

1995-12-01

Daily rainfall from two sites in central and southern England was stratified according to the presence or absence of weather fronts and then cross-tabulated with the prevailing Lamb Weather Type (LWT). A semi-Markov chain model was developed for simulating daily sequences of LWTs from matrices of transition probabilities between weather types for the British Isles 1970-1990. Daily and annual rainfall distributions were then simulated from the prevailing LWTs using historic conditional probabilities for precipitation occurrence and frontal frequencies. When compared with a conventional rainfall generator the frontal model produced improved estimates of the overall size distribution of daily rainfall amounts and in particular the incidence of low-frequency high-magnitude totals. Further research is required to establish the contribution of individual frontal sub-classes to daily rainfall totals and of long-term fluctuations in frontal frequencies to conditional probabilities.

Time-frequency dynamics during sleep spindles on the EEG in rodents with a genetic predisposition to absence epilepsy (WAG/Rij rats)

NASA Astrophysics Data System (ADS)

Hramov, Alexander E.; Sitnikova, Evgenija Y.; Pavlov, Alexey N.; Grubov, Vadim V.; Koronovskii, Alexey A.; Khramova, Marina V.

2015-03-01

Sleep spindles are known to appear spontaneously in the thalamocortical neuronal network of the brain during slow-wave sleep; pathological processes in the thalamocortical network may be the reason of the absence epilepsy. The aim of the present work is to study developed changes in the time-frequency structure of sleep spindles during the progressive development of the absence epilepsy in WAG/Rij rats. EEG recordings were made at age 7 and 9 months. Automatic recognition and subsequent analysis of sleep spindles on the EEG were performed using the continuous wavelet transform. The duration of epileptic discharges and the total duration of epileptic activity were found to increase with age, while the duration of sleep spindles, conversely, decreased. In terms of the mean frequency, sleep spindles could be divided into three classes: `slow' (mean frequency 9.3Hz), `medium' (11.4Hz), and `fast' (13.5Hz). Slow and medium (transitional) spindles in five-month-old animals showed increased frequency from the beginning to the end of the spindle. The more intense the epilepsy is, the shorter are the durations of spindles of all types. The mean frequencies of `medium' and `fast' spindles were higher in rats with more intense signs of epilepsy. Overall, high epileptic activity in WAG/Rij rats was linked with significant changes in spindles of the transitional type, with less marked changes in the two traditionally identified types of spindle, slow and fast.

Characterizing riverbed sediment using high-frequency acoustics 2: scattering signatures of Colorado River bed sediment in Marble and Grand Canyons

USGS Publications Warehouse

Buscombe, Daniel D.; Grams, Paul E.; Kaplinski, Matt A.

2014-01-01

In this, the second of a pair of papers on the statistical signatures of riverbed sediment in high-frequency acoustic backscatter, spatially explicit maps of the stochastic geometries (length- and amplitude-scales) of backscatter are related to patches of riverbed surfaces composed of known sediment types, as determined by geo-referenced underwater video observations. Statistics of backscatter magnitudes alone are found to be poor discriminators between sediment types. However, the variance of the power spectrum, and the intercept and slope from a power-law spectral form (termed the spectral strength and exponent, respectively) successfully discriminate between sediment types. A decision-tree approach was able to classify spatially heterogeneous patches of homogeneous sands, gravels (and sand-gravel mixtures), and cobbles/boulders with 95, 88, and 91% accuracy, respectively. Application to sites outside the calibration, and surveys made at calibration sites at different times, were plausible based on observations from underwater video. Analysis of decision trees built with different training data sets suggested that the spectral exponent was consistently the most important variable in the classification. In the absence of theory concerning how spatially variable sediment surfaces scatter high-frequency sound, the primary advantage of this data-driven approach to classify bed sediment over alternatives is that spectral methods have well understood properties and make no assumptions about the distributional form of the fluctuating component of backscatter over small spatial scales.

Configurations of high-frequency ultrasonics complex vibration systems for packaging in microelectronics.

PubMed

Tsujino, Jiromaru; Harada, Yoshiki; Ihara, Shigeru; Kasahara, Kohei; Shimizu, Masanori; Ueoka, Tetsugi

2004-04-01

Ultrasonic high-frequency complex vibrations are effective for various ultrasonic high-power applications. Three types of ultrasonic complex vibration system with a welding tip vibrating elliptical to circular locus for packaging in microelectronics were studied. The complex vibration sources are using (1) a longitudinal-torsional vibration converter with diagonal slits that is driven only by a longitudinal vibration source, (2) a complex transverse vibration rod with several stepped parts that is driven by two longitudinal vibration source crossed at a right angle and (3) a longitudinal vibration circular disk and three longitudinal transducers that are installed at the circumference of the disk.

Vibration detection of component health and operability

NASA Technical Reports Server (NTRS)

Baird, B. C.

1975-01-01

In order to prevent catastrophic failure and eliminate unnecessary periodic maintenance in the shuttle orbiter program environmental control system components, some means of detecting incipient failure in these components is required. The utilization was investigated of vibrational/acoustic phenomena as one of the principal physical parameters on which to base the design of this instrumentation. Baseline vibration/acoustic data was collected from three aircraft type fans and two aircraft type pumps over a frequency range from a few hertz to greater than 3000 kHz. The baseline data included spectrum analysis of the baseband vibration signal, spectrum analysis of the detected high frequency bandpass acoustic signal, and amplitude distribution of the high frequency bandpass acoustic signal. A total of eight bearing defects and two unbalancings was introduced into the five test items. All defects were detected by at least one of a set of vibration/acoustic parameters with a margin of at least 2:1 over the worst case baseline. The design of a portable instrument using this set of vibration/acoustic parameters for detecting incipient failures in environmental control system components is described.

An investigation of the effects of pitch-roll (de)coupling on helicopter handling qualities

NASA Technical Reports Server (NTRS)

Blanken, C. L.; Pausder, H. J.; Ockier, C. J.

1995-01-01

An extensive investigation of the effects of pitch-roll coupling on helicopter handling qualities was performed by the U.S. Army and Deutsche Forschungsanstalt fur Luft- und Raumfahrt (DLR), using a NASA ground-based and a DLR in-flight simulator. Over 90 different coupling configurations were evaluated using a high gain roll-axis tracking task. The results show that although the current ADS-33C coupling criterion discriminates against those types of coupling typical of conventionally controlled helicopters, it is not always suited for the prediction of handling qualities of helicopters with modern control systems. Based on the observation that high frequency inputs during tracking are used to alleviate coupling, a frequency domain pitch-roll coupling criterion that uses the average coupling ratio between the bandwidth and neutral stability frequency is formulated. This criterion provides a more comprehensive coverage with respect to the different types of coupling, shows excellent consistency, and has the additional benefit that compliance testing data are obtained from the bandwidth/phase delay tests, so that no additional flight testing is needed.

Extended-area nanostructuring of TiO2 with femtosecond laser pulses at 400 nm using a line focus.

PubMed

Das, Susanta Kumar; Dasari, Kiran; Rosenfeld, Arkadi; Grunwald, Ruediger

2010-04-16

An efficient way to generate nanoscale laser-induced periodic surface structures (LIPSS) in rutile-type TiO(2) with frequency-converted femtosecond laser pulses at wavelengths around 400 nm is reported. Extended-area structuring on fixed and moving substrates was obtained by exploiting the line focus of a cylindrical lens. Under defined conditions with respect to pulse number, pulse energy and scanning velocity, two types of ripple-like LIPSS with high and low spatial frequencies (HSFL, LSFL) with periods in the range of 90 nm and 340 nm, respectively, were formed. In particular, lower numbers of high energetic pulses favour the generation of LSFL whereas higher numbers of lower energetic pulses enable the preferential creation of HSFL. Theoretical calculations on the basis of the Drude model support the assumption that refractive index changes by photo-excited carriers are a major mechanism responsible for LSFL. Furthermore, the appearance of random substructures as small as 30 nm superimposing low spatial frequency ripples is demonstrated and their possible origin is discussed.

High-power 266 nm ultraviolet generation in yttrium aluminum borate.

PubMed

Liu, Qiang; Yan, Xingpeng; Gong, Mali; Liu, Hua; Zhang, Ge; Ye, Ning

2011-07-15

A yttrium aluminum borate [YAl(3)(BO(3))(4)] (YAB) crystal with UV cutoff wavelength of 165 nm is used as the nonlinear optical crystal for fourth harmonic generation. The fundamental frequency laser at 1064 nm from an Nd:YVO(4) master oscillator power amplifier laser was frequency doubled to 532 nm. Using the type I phase-matching YAB crystal, a 5.05 W average power 266 nm UV laser was obtained at the pulse repetition frequency of 65 kHz, corresponding to the conversion efficiency of 12.3% from 532 to 266 nm. The experimental results show great potential for the application of using YAB as a nonlinear optical crystal to get high-power fourth harmonic generation. © 2011 Optical Society of America

Dielectric and modulus studies of polycrystalline BaZrO3 ceramic

NASA Astrophysics Data System (ADS)

Saini, Deepash S.; Singh, Sunder; Kumar, Anil; Bhattacharya, D.

2018-05-01

In the present work, dielectric and modulus studies of polycrystalline BaZrO3 ceramic, prepared by modified combustion method followed by conventional sintering, are investigated over the frequency range of 100 Hz to 106 Hz at different temperatures from 250 to 500 °C in air. The high value of dielectric constant (ɛ' ˜ 103) of BaZrO3 at high temperature and low frequency can be attributed to the Maxwell-Wagner polarization mechanism as well as to the thermally activated mechanism of charge carriers. Electric modulus reveal two type relaxations in the 250 °C to 800 °C temperature region as studied at different frequencies over 100 Hz to 106 Hz in air.

Academic stress levels were positively associated with sweet food consumption among Korean high-school students.

PubMed

Kim, Yeonsoo; Yang, Hye Young; Kim, Ae-Jung; Lim, Yunsook

2013-01-01

The objectives of the present study were to identify the association among levels of persistent academic stress, appetite, and dietary habits and to determine the specific types of sweet foods consumed by Korean high-school students according to their academic stress levels. The study participants included 333 high-school students in the 10th to 12th grades in Kyunggi Province, Korea. The level of academic stress was scored with a 75-item academic stress scale and was categorized as high, medium, or low. A food-frequency questionnaire was used to measure the sugar intake from sweet foods. Korean high-school students with a high academic stress level had larger meals than the other students. Compared with students with low academic stress, the students with high academic stress had a higher frequency of sugar intake from the following food types: confectionaries, candies and chocolates, breads, and flavored milk. Moreover, compared with students with low academic stress, the students with high academic stress had a higher total intake of sugar from the following food types: confectionaries, candies, chocolates, flavored milk, traditional Korean beverages, and spicy, sweet, and fried rice cakes. Unhealthy stress-related food choices may compromise high-school students' health and contribute to their morbidity. The findings of the present study could be used to help nutritionists develop effective strategies for nutritional education and counseling to improve adolescent health. Copyright © 2013 Elsevier Inc. All rights reserved.

Polydactyly in the American Indian.

PubMed

Bingle, G J; Niswander, J D

1975-01-01

Polydactyly has an incidence in the American Indian twice that of Caucasians. A minimum estimate of this incidence is 2.40 per 1,000 live births. Preaxial type 1 has an incidence three to four times that reported for Caucasians or Negroes. The overall sex ratio in Indians is distorted with more males affected than females. The preaxial type 1 anomaly has a strong predilection for the hands and always is unilateral in contrast to postaxial type B where more than one-half are bilateral. The evidence to date, consisting of varying incidences of specific types of polydactyly among American whites, Negroes, and Indians in varying enviroments, suggests different gene-frequencies for polydactyly in each population. The incidence in Indians with 50% Caucasian admixture suggests that the factors controlling polydactyly are in large part genetically determined. Family studies and twin studies reported elsewhere offer no clear-cut genetic model which explains the highly variable gene frequencies.

Polydactyly in the American Indian.

PubMed Central

Bingle, G J; Niswander, J D

1975-01-01

Polydactyly has an incidence in the American Indian twice that of Caucasians. A minimum estimate of this incidence is 2.40 per 1,000 live births. Preaxial type 1 has an incidence three to four times that reported for Caucasians or Negroes. The overall sex ratio in Indians is distorted with more males affected than females. The preaxial type 1 anomaly has a strong predilection for the hands and always is unilateral in contrast to postaxial type B where more than one-half are bilateral. The evidence to date, consisting of varying incidences of specific types of polydactyly among American whites, Negroes, and Indians in varying enviroments, suggests different gene-frequencies for polydactyly in each population. The incidence in Indians with 50% Caucasian admixture suggests that the factors controlling polydactyly are in large part genetically determined. Family studies and twin studies reported elsewhere offer no clear-cut genetic model which explains the highly variable gene frequencies. PMID:1155454

HLA class II and TNF genes in African Americans from the Southeastern United States: regional differences in allele frequencies.

PubMed

Kuffner, Tamara; Whitworth, William; Jairam, Maya; McNicholl, Janet

2003-06-01

Knowledge of population major histocompatibility complex gene frequencies is important for construction of organ donor pools and for studies of disease association. Human leukocyte antigen DRB1 (HLA-DRB1), HLA-DQB1, and TNFalpha -308 (G-A) promoter genetic typing was performed in 112 healthy, unrelated African Americans (AAs) from the southeastern United States. Allele frequencies were compared with published frequency data from other AA populations. Our AA population had the highest frequency of HLA- DRB1*09 (6.7%) reported in any AA population. The frequency of the TNF alpha -308A polymorphism was also high (14.4%), when compared with published frequencies in AAs. Significant regional differences in the distribution of most HLA-DRB1 and HLA-DQB1 alleles were observed in all AA populations examined. The AA HLA-DRB1 and -DQB1 frequencies also differed from published Caucasian frequencies. This is the first report describing the distribution of TNF alpha promoter alleles in the Southeastern United States. The high DRB1*09 and TNF alpha -308A allele frequencies of our population most resemble the frequencies of these alleles in certain West African populations. These varying major histocompatibility complex gene frequencies may reflect different regional population structures among AAs in the United States, which may be due to differences in ancestral origins, migration, and racial admixture.

Crash prediction method for freeway facilities with high occupancy vehicle (HOV) and high occupancy toll (HOT) lanes.

DOT National Transportation Integrated Search

2015-07-01

This study developed methods for estimating the expected crash frequency of urban freeway segments : with HOV or HOT lanes. The safety impacts of the type of separation between the managed lanes and : general purpose lanes were examined. Separate mod...

High frequencies of Th1-type CD4(+) T cells specific to HTLV-1 Env and Tax proteins in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis.

PubMed

Goon, Peter K C; Hanon, Emmanuel; Igakura, Tadahiko; Tanaka, Yuetsu; Weber, Jonathan N; Taylor, Graham P; Bangham, Charles R M

2002-05-01

CD4(+) T cells are critical for inducing and maintaining efficient humoral and cellular immune responses to pathogens. The CD4(+) T-cell response in human T-lymphotropic virus 1 (HTLV-1) infection has not been studied in detail. However, CD4(+) T cells have been shown to predominate in early lesions in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). We present direct estimates of HTLV-1 Env- and Tax-specific CD4(+) T-cell frequencies in patients infected with HTLV-1. We first showed that there was a strong bias toward the Th1 phenotype in these HTLV-1-specific CD4(+) T cells in patients with HAM/TSP. We then demonstrated significantly higher frequencies of HTLV-1-specific Th1-type CD4(+) T cells in HAM/TSP patients than in asymptomatic HTLV-1 carriers. The majority of these HTLV-1-specific CD4(+) T cells did not express HTLV-1 Tax and were therefore unlikely to be infected by HTLV-1. High frequencies of activated HTLV-1-specific CD4(+) T cells of the Th1 phenotype might contribute to the initiation or pathogenesis of HAM/TSP and other HTLV-1-associated inflammatory diseases.

Recent advances in capacitance type of blade tip clearance measurements

NASA Technical Reports Server (NTRS)

Barranger, John P.

1988-01-01

Two recent electronic advances at NASA-Lewis that meet the blade tip clearance needs of a wide class of fans, compressors, and turbines are described. The first is a frequency modulated (FM) oscillator that requires only a single low cost ultrahigh frequency operational amplifier. Its carrier frequency is 42.8 MHz when used with a 61 cm long hermetically sealed coaxial cable. The oscillator can be calibrated in the static mode and has a negative peak frequency deviation of 400 kHz for a typical rotor blade. High temperature performance tests of the probe and 13 cm of the adjacent cable show good accuracy up to 600 C, the maximum which produces a clearance error of + or - 10 microns at a clearance of 500 microns. In the second advance, a guarded probe configuration allows a longer cable capacitance. The capacitance of the probe is part of a small time constant feedback in a high speed operational amplifier. The solution of the governing differential equation is applied to a ramp type of input. The results show an amplifier output that contains a term which is proportional to the derivative of the feedback capacitance. The capacitance is obtained by subtracting a balancing reference channel followed by an integration stage.

The morphologic and immunohistochemical spectrum of papillary renal cell carcinoma: study including 132 cases with pure type 1 and type 2 morphology as well as tumors with overlapping features.

PubMed

Chevarie-Davis, Myriam; Riazalhosseini, Yasser; Arseneault, Madeleine; Aprikian, Armen; Kassouf, Wassim; Tanguay, Simon; Latour, Mathieu; Brimo, Fadi

2014-07-01

Papillary renal cell carcinomas (pRCC) are classically divided into type 1 and 2 tumors. However, many cases do not fulfill all the criteria for either type. We describe the clinical, morphologic, and immunohistochemical (IHC) features of 132 pRCCs to better characterize the frequency and nature of tumors with overlapping features. Cases were reviewed and classified; IHC evaluation of CK7, EMA, TopoIIα, napsin A, and AMACR was performed on 95 cases. The frequencies of type 1, type 2, and "overlapping" pRCC were 25%, 28%, and 47%, respectively. The 2 categories of "overlapping" tumors were: (1) cases with bland cuboidal cells but no basophilic cytoplasm (type A); and (2) cases with predominantly type 1 histology admixed with areas showing prominent nucleoli (type B). The pathologic stage of "overlapping" cases showed concordance with type 1 tumors. Using the 2 discriminatory markers (CK7, EMA), "type A" cases were similar to type 1. Although the high-nuclear grade areas of "type B" tumors showed some staining differences from their low-nuclear grade counterpart, their IHC profile was closer to type 1. Single nucleotide polymorphism array results, although preliminary and restricted to only 9 cases (3 with overlapping features), also seemed to confirm those findings. In conclusion, we demonstrate that variations in cytoplasmic quality and/or presence of high-grade nuclei in tumors otherwise displaying features of type 1 pRCCs are similar in stage and IHC profile those with classic type 1 histology, suggesting that their spectrum might be wider than originally described.

A systematic study of (NH4)2S passivation (22%, 10%, 5%, or 1%) on the interface properties of the Al2O3/In0.53Ga0.47As/InP system for n-type and p-type In0.53Ga0.47As epitaxial layers

NASA Astrophysics Data System (ADS)

O'Connor, É.; Brennan, B.; Djara, V.; Cherkaoui, K.; Monaghan, S.; Newcomb, S. B.; Contreras, R.; Milojevic, M.; Hughes, G.; Pemble, M. E.; Wallace, R. M.; Hurley, P. K.

2011-01-01

In this work, we present the results of an investigation into the effectiveness of varying ammonium sulphide (NH4)2S concentrations in the passivation of n-type and p-type In0.53Ga0.47As. Samples were degreased and immersed in aqueous (NH4)2S solutions of concentrations 22%, 10%, 5%, or 1% for 20 min at 295 K, immediately prior to atomic layer deposition of Al2O3. Multi-frequency capacitance-voltage (C-V) results on capacitor structures indicate that the lowest frequency dispersion over the bias range examined occurs for n-type and p-type devices treated with the 10%(NH4)2S solution. The deleterious effect on device behavior of increased ambient exposure time after removal from 10%(NH4)2S solution is also presented. Estimations of the interface state defect density (Dit) for the optimum 10%(NH4)2S passivated In0.53Ga0.47As devices extracted using an approximation to the conductance method, and also extracted using the temperature-modified high-low frequency C-V method, indicate that the same defect is present over n-type and p-type devices having an integrated Dit of ˜2.5×1012 cm-2 (±1×1012 cm-2) with the peak density positioned in the middle of the In0.53Ga0.47As band gap at approximately 0.37 eV (±0.03 eV) from the valence band edge. Both methods used for extracting Dit show very good agreement, providing evidence to support that the conductance method can be applied to devices incorporating high-k oxides on In0.53Ga0.47As.

Quasi-phase-matching of the dual-band nonlinear left-handed metamaterial

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

Liu, Yahong, E-mail: yhliu@nwpu.edu.cn; Song, Kun; Gu, Shuai

2014-11-17

We demonstrate a type of nonlinear meta-atom creating a dual-band nonlinear left-handed metamaterial (DNLHM). The DNLHM operates at two distinct left-handed frequency bands where there is an interval of one octave between the two center frequencies. Under the illumination of a high-power signal at the first left-handed frequency band corresponding to fundamental frequency (FF), second-harmonic generation (SHG) is observed at the second left-handed band. This means that our DNLHM supports backward-propagating waves both at FF and second-harmonic (SH) frequency. We also experimentally demonstrate quasi-phase-matching configurations for the backward SHG. This fancy parametric process can significantly transmits the SH generated bymore » an incident FF wave.« less

Investigation of the validity of Reynolds averaged turbulence models at the frequencies that occur in turbomachinery

NASA Technical Reports Server (NTRS)

Kuhn, Gary D.

1988-01-01

Turbulent flows subjected to various kinds of unsteady disturbances were simulated using a large-eddy-simulation computer code for flow in a channel. The disturbances were: a normal velocity expressed as a traveling wave on one wall of the channel; staggered blowing and suction distributions on the opposite walls of the channel; and oscillations of the mean flow through the channel. The wall boundary conditions were designed to simulate the effects of wakes of a stator stage passing through a rotor channel in a turbine. The oscillating flow simulated the effects of a pressure pulse moving over the rotor blade boundary layer. The objective of the simulations was to provide better understanding of the effects of time-dependent disturbances on the turbulence of a boundary layer and of the underlying physical phenomena regarding the basic interaction between the turbulence and external disturbances of the type found in turbomachinery. Results showed that turbulence is sensitive to certain ranges of frequencies of disturbances. However, no direct connection was found between the frequency of imposed disturbances and characteristic burst frequency of turbulence. New insight into the nature of turbulence at high frequencies was found. The viscous phenomena near solid walls was found to be the dominant influence for high frequency perturbations. At high frequencies, the turbulence was found to be undisturbed, remaining the same as for the steady mean flow. A transition range exists between the high frequency range and the low, or quasi-steady, range in which the turbulence is not predictable by either quasi-steady models or the steady flow model. The limiting lowest frequency for use of the steady flow turbulence model is that for which the viscous Stokes layer based on the blade passing frequency is thicker than the laminar sublayer.

Relative locations between shallow very low frequency earthquakes and low frequency tremors investigated based on near-filed BBOBS records

NASA Astrophysics Data System (ADS)

Chi, W. C.; To, A.; Chen, W. J.; Konishi, K.

2017-12-01

Two types of anomalous seismic events of long duration with signals depleted in high frequencies relative to most earthquakes are recorded in a network of broadband ocean bottom seismometers (BBOBS) deployed at shallow Nankai subduction zone (DONET1). The first type is very low frequency earthquake (VLFE) whose signals are observed both in the lower and higher frequency ranges of the 0.1 Hz microseism band, which are 0.02-0.06 Hz and 2-8 Hz. The second type is low frequency tremor (LFT), whose signals are only observed at 2-8 Hz. The waveform similarity at 2-8 Hz and concurrences of the two types of event warrant further investigations on whether they represent the same phenomenon or not. Previously, To et al., (2015) examined the relation between VLFEs and LFTs by comparing their maximum amplitude at two different frequency ranges, 2-8 Hz and 0.02-0.05 Hz. The comparison showed that the maximum amplitudes measured at the two frequency ranges correlate positively for VLFEs, that is, large magnitude VLFEs showed large amplitude in both frequency ranges. The comparison also showed that the amplitude measured at 2-8 Hz were larger for VLFEs than those of LFTs. Based on such amplitude observations, they concluded that VLFEs and LFTs are likely smaller and larger events of the same phenomenon. Here, we examined the relation between the two types of event based on their spatial distribution. Their distributions should be similar if they represent the same phenomenon. The data are broadband seismographs of 20 stations of DONET1. We detected 144 VLFEs and 775 LFTs during the intense LFT/VLFE activity period of one week in October 2015. Events are located using an envelope cross correlation method. We used the root-mean-square (RMS) amplitudes constructed from the two horizontal components, bandpass filtered at 2-­8 Hz and then smoothed by taking a moving average with a window length of 5 s. The obtained distributions of VLFEs and LFTs show similar patterns. They both formed two spatially separated groups, one in the northeast side and the other in the southwest side of DONET1. There is no spatial segregation between the two event types, supporting the speculation that VLFEs and LFEs are different manifestations of the same phenomenon. Acknowledgement: Data of DONET1 were downloaded through https://hinetwww11.bosai.go.jp.

[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.

The Tropical Convective Spectrum. Part 1; Archetypal Vertical Structures

NASA Technical Reports Server (NTRS)

Boccippio, Dennis J.; Petersen, Walter A.; Cecil, Daniel J.

2005-01-01

A taxonomy of tropical convective and stratiform vertical structures is constructed through cluster analysis of 3 yr of Tropical Rainfall Measuring Mission (TRMM) "warm-season" (surface temperature greater than 10 C) precipitation radar (PR) vertical profiles, their surface rainfall, and associated radar-based classifiers (convective/ stratiform and brightband existence). Twenty-five archetypal profile types are identified, including nine convective types, eight stratiform types, two mixed types, and six anvil/fragment types (nonprecipitating anvils and sheared deep convective profiles). These profile types are then hierarchically clustered into 10 similar families, which can be further combined, providing an objective and physical reduction of the highly multivariate PR data space that retains vertical structure information. The taxonomy allows for description of any storm or local convective spectrum by the profile types or families. The analysis provides a quasi-independent corroboration of the TRMM 2A23 convective/ stratiform classification. The global frequency of occurrence and contribution to rainfall for the profile types are presented, demonstrating primary rainfall contribution by midlevel glaciated convection (27%) and similar depth decaying/stratiform stages (28%-31%). Profiles of these types exhibit similar 37- and 85-GHz passive microwave brightness temperatures but differ greatly in their frequency of occurrence and mean rain rates, underscoring the importance to passive microwave rain retrieval of convective/stratiform discrimination by other means, such as polarization or texture techniques, or incorporation of lightning observations. Close correspondence is found between deep convective profile frequency and annualized lightning production, and pixel-level lightning occurrence likelihood directly tracks the estimated mean ice water path within profile types.

Role of the mouse retinal photoreceptor ribbon synapse in visual motion processing for optokinetic responses.

PubMed

Sugita, Yuko; Araki, Fumiyuki; Chaya, Taro; Kawano, Kenji; Furukawa, Takahisa; Miura, Kenichiro

2015-01-01

The ribbon synapse is a specialized synaptic structure in the retinal outer plexiform layer where visual signals are transmitted from photoreceptors to the bipolar and horizontal cells. This structure is considered important in high-efficiency signal transmission; however, its role in visual signal processing is unclear. In order to understand its role in visual processing, the present study utilized Pikachurin-null mutant mice that show improper formation of the photoreceptor ribbon synapse. We examined the initial and late phases of the optokinetic responses (OKRs). The initial phase was examined by measuring the open-loop eye velocity of the OKRs to sinusoidal grating patterns of various spatial frequencies moving at various temporal frequencies for 0.5 s. The mutant mice showed significant initial OKRs with a spatiotemporal frequency tuning (spatial frequency, 0.09 ± 0.01 cycles/°; temporal frequency, 1.87 ± 0.12 Hz) that was slightly different from the wild-type mice (spatial frequency, 0.11 ± 0.01 cycles/°; temporal frequency, 1.66 ± 0.12 Hz). The late phase of the OKRs was examined by measuring the slow phase eye velocity of the optokinetic nystagmus induced by the sinusoidal gratings of various spatiotemporal frequencies moving for 30 s. We found that the optimal spatial and temporal frequencies of the mutant mice (spatial frequency, 0.11 ± 0.02 cycles/°; temporal frequency, 0.81 ± 0.24 Hz) were both lower than those in the wild-type mice (spatial frequency, 0.15 ± 0.02 cycles/°; temporal frequency, 1.93 ± 0.62 Hz). These results suggest that the ribbon synapse modulates the spatiotemporal frequency tuning of visual processing along the ON pathway by which the late phase of OKRs is mediated.

Role of the Mouse Retinal Photoreceptor Ribbon Synapse in Visual Motion Processing for Optokinetic Responses

PubMed Central

Sugita, Yuko; Araki, Fumiyuki; Chaya, Taro; Kawano, Kenji; Furukawa, Takahisa; Miura, Kenichiro

2015-01-01

The ribbon synapse is a specialized synaptic structure in the retinal outer plexiform layer where visual signals are transmitted from photoreceptors to the bipolar and horizontal cells. This structure is considered important in high-efficiency signal transmission; however, its role in visual signal processing is unclear. In order to understand its role in visual processing, the present study utilized Pikachurin-null mutant mice that show improper formation of the photoreceptor ribbon synapse. We examined the initial and late phases of the optokinetic responses (OKRs). The initial phase was examined by measuring the open-loop eye velocity of the OKRs to sinusoidal grating patterns of various spatial frequencies moving at various temporal frequencies for 0.5 s. The mutant mice showed significant initial OKRs with a spatiotemporal frequency tuning (spatial frequency, 0.09 ± 0.01 cycles/°; temporal frequency, 1.87 ± 0.12 Hz) that was slightly different from the wild-type mice (spatial frequency, 0.11 ± 0.01 cycles/°; temporal frequency, 1.66 ± 0.12 Hz). The late phase of the OKRs was examined by measuring the slow phase eye velocity of the optokinetic nystagmus induced by the sinusoidal gratings of various spatiotemporal frequencies moving for 30 s. We found that the optimal spatial and temporal frequencies of the mutant mice (spatial frequency, 0.11 ± 0.02 cycles/°; temporal frequency, 0.81 ± 0.24 Hz) were both lower than those in the wild-type mice (spatial frequency, 0.15 ± 0.02 cycles/°; temporal frequency, 1.93 ± 0.62 Hz). These results suggest that the ribbon synapse modulates the spatiotemporal frequency tuning of visual processing along the ON pathway by which the late phase of OKRs is mediated. PMID:25955222

Stability and modal analysis of shock/boundary layer interactions

NASA Astrophysics Data System (ADS)

Nichols, Joseph W.; Larsson, Johan; Bernardini, Matteo; Pirozzoli, Sergio

2017-02-01

The dynamics of oblique shock wave/turbulent boundary layer interactions is analyzed by mining a large-eddy simulation (LES) database for various strengths of the incoming shock. The flow dynamics is first analyzed by means of dynamic mode decomposition (DMD), which highlights the simultaneous occurrence of two types of flow modes, namely a low-frequency type associated with breathing motion of the separation bubble, accompanied by flapping motion of the reflected shock, and a high-frequency type associated with the propagation of instability waves past the interaction zone. Global linear stability analysis performed on the mean LES flow fields yields a single unstable zero-frequency mode, plus a variety of marginally stable low-frequency modes whose stability margin decreases with the strength of the interaction. The least stable linear modes are grouped into two classes, one of which bears striking resemblance to the breathing mode recovered from DMD and another class associated with revolving motion within the separation bubble. The results of the modal and linear stability analysis support the notion that low-frequency dynamics is intrinsic to the interaction zone, but some continuous forcing from the upstream boundary layer may be required to keep the system near a limit cycle. This can be modeled as a weakly damped oscillator with forcing, as in the early empirical model by Plotkin (AIAA J 13:1036-1040, 1975).

The fine structure of Langmuir waves observed upstream of the bow shock at Venus

NASA Technical Reports Server (NTRS)

Hospodarsky, G. B.; Gurnett, D. A.; Kurth, W. S.; Kivelson, M. G.; Strangeway, R. J.; Bolton, S. J.

1994-01-01

Highly structured Langmuir waves, also known as electron plasma oscillations, have been observed in the foreshock of Venus using the plasma wave experiment on the Galileo spacecraft during the gravity assist flyby on February 10, 1990. The Galileo wideband sampling system provides digital electric field waveform measurements at sampling rates up to 201,600 samples per second, much higher than any previous instrument of this type. The main Langmuir wave emission band occurs near the local electron plasma frequency, which was approximately 43 kHz. The Langmuir waves are observed to shift above and below the plasma frequency, sometimes by as much as 20 kHz. The shifts in frequency are closely correlated with the downstream distance from the tangent field line, implying that the shifts are controlled by the electron beam velocity. Considerable fine structure is also evident, with time scales as short as 0.15 milliseconds, corresponding to spatial scales of a few tens of Debye lengths. The frequency spectrum often consists of beat-type waveforms, with beat frequencies ranging from 0.2 to 7 kHz, and in a few cases, isolated wavepackets. The peak electric field strengths are approximately 1 mV/m. These field strengths are too small for strongly nonlinear processes to be important. The beat-type waveforms are suggestive of a parametric decay process.

Co2+Ti4+ substituted Z-type barium ferrite with enhanced imaginary permeability and resonance frequency

NASA Astrophysics Data System (ADS)

Li, Z. W.; Guoqing, Lin; Chen, Linfeng; Yuping, Wu; Ong, C. K.

2006-03-01

Co2+Ti4+ substitution for Fe3+ in Co2Z (Ba3Co2Fe24O41) has been prepared. The crystal structure and static and high-frequency magnetic properties have been studied for Ba3Co2+xTixFe24-2xO41 and the corresponding ferrite/polymer composites. As compared to the general Co2Z ferrite/polymer composite, the CoTi substituted ferrite/polymer composite with x=1.0 has a high natural resonance frequency (4.5 GHz), due to its large out-of-plane anisotropy fields Hθ. Furthermore, the maximum imaginary permeability μmax'' is increased by about 50%. The increase is attributed to a decreased damping coefficient, based on the curve-fitted results to the complex permeability spectra. The composites are good electromagnetic attenuation materials with low reflectivity and broad bandwidth at microwave frequencies.

Contribution of autonomic dysfunction to abnormal exercise blood pressure in type 2 diabetes mellitus.

PubMed

Weston, Kassia S; Sacre, Julian W; Jellis, Christine L; Coombes, Jeff S

2013-01-01

The purpose of this study was to compare the presence and severity of autonomic dysfunction in type 2 diabetes mellitus patients, with and without exaggerated blood pressure responses to exercise. We performed a cross-sectional analysis of 98 patients with type 2 diabetes mellitus (aged 59±9). Both time (standard deviation of RR intervals, root-mean-square of successive RR interval differences) and frequency (total spectral power, high frequency, low frequency, very low frequency) domains of heart rate variability were analysed in a 5 min recording at rest and 20 min after a maximal treadmill test. An exaggerated blood pressure response to exercise was identified by peak blood pressure ≥190/105 mmHg (women) or ≥210/105 mmHg (men). Each group of either exaggerated exercise blood pressure response or normal blood pressure response consisted of 49 patients. At rest there were no significant differences between groups for all time and frequency domain parameters of heart rate variability. Post-exercise, there was a significant (p<0.05) reduction in the SDNN, RMSSD and TP in the exaggerated exercise blood pressure group. Independent correlates (p<0.01) of exercise systolic blood pressure included post-exercise TP, resting systolic blood pressure, cardiac autonomic neuropathy and beta-blockers (beta=-0.28, adj. R² = 0.32, p<0.001). Reduced post-exercise heart rate variability in patients with type 2 diabetes mellitus, with an exaggerated exercise blood pressure response suggests preclinical autonomic dysfunction characterized by impaired vagal modulation. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Hemorheology and heart rate variability in patients with diabetes mellitus type 2.

PubMed

Velcheva, Irena; Damianov, Petar; Mantarova, Stefka; Antonova, Nadia

2011-01-01

Our study aimed to investigate the relationship between hemorheological parameters and heart rate variability (HRV) in patients with diabetes mellitus type 2. Hemorheological variables, including hematocrit (Ht), fibrinogen (Fib), whole blood (WBV) and plasma viscosity (PV) at shear rates of 0.0237 s(-1) to 128.5 s(-1) were examined in 20 patients with diabetes mellitus type 2 and in 10 control subjects. They all underwent non-invasive short-term monitoring of heart rate at rest and after passive head-up tilt. Measurement of the R-R intervals and calculation of the time domain parameters and the power spectral data were performed by our softwear, using fast Fourier transformation. Significant increase of Fib and WBV in the patients in comparison to controls was found within the range of shear rates 0.0237 s(-1) to 128.5 s(-1). In the diabetic patients parallel decrease of the total power (TP), the low frequency spectral power (LF) and of the mean RR and mild increase of the low frequency-high frequency ratio (LF/HF) at rest were established. This tendency was kept after the passive tilt. In patients with diabetes mellitus type 2 the increased blood viscosity was associated with reduced HRV.

Study of ELM Density Turbulence using the Upgraded Phase Contrast Imaging on DIII-D

NASA Astrophysics Data System (ADS)

Rost, J. C.; Davis, E. M.; Marinoni, A.; Porkolab, M.; Burrell, K. H.

2016-10-01

Recent studies of the turbulent density fluctuations accompanying ELMs in mixed ELM-type discharges have exploited the expanded wavenumber range of the upgraded Phase Contrast Imaging (PCI) diagnostic. The PCI data demonstrate the difference between the fluctuations generated by Type I ELMs, which are broadband in frequency and wavelength, and those generated by Type III ELMs, which are similar in amplitude but restricted to long wavelengths, suggesting that turbulence may play a significant role in Type I ELM transport. The high frequency response of PCI makes it ideal for studying the ELM-associated density fluctuations, which are observed at frequencies up to several MHz, evolve on time scales of 10s of μs, and persist after the magnetic component of the ELM has decayed away. The upgraded PCI, with independent systems for long and short wavelength detection (k < 5 cm-1 and 1 < k < 30 cm-1 respectively), demonstrated coverage of the full wavenumber range of interest. Work supported in part by the US Department of Energy under DE-FG02-94ER54235, DE-FC02-04ER54698, and DE-FC02-99ER54512.

A comparison study of different RF shields for an 8-element transceive small animal array at 9.4T.

PubMed

Jin, Jin; Li, Yu; Liu, Feng; Weber, Ewald; Crozier, Stuart

2011-01-01

In this study, three types of radio-frequency shields are studied and compared in the context of ultra-high field small-animal magnetic resonance imaging. It has been demonstrated that the coil penetration depth and mutual coupling between the coils depend heavily on the type of shield employed. The results were used to guide the design of a 9.4T 8-element transceive small animal array, which provides high overall coil penetration.

21 CFR 884.4160 - Unipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2010 CFR

2010-04-01

... temperatures by directing a high frequency electrical current through the tissue between an energized probe and... generator, probes and electrical cables, and a patient grounding plate. This generic type of device does not...

21 CFR 884.4160 - Unipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2011 CFR

2011-04-01

... temperatures by directing a high frequency electrical current through the tissue between an energized probe and... generator, probes and electrical cables, and a patient grounding plate. This generic type of device does not...

21 CFR 884.4160 - Unipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2012 CFR

2012-04-01

... temperatures by directing a high frequency electrical current through the tissue between an energized probe and... generator, probes and electrical cables, and a patient grounding plate. This generic type of device does not...

21 CFR 884.4160 - Unipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2014 CFR

2014-04-01

... temperatures by directing a high frequency electrical current through the tissue between an energized probe and... generator, probes and electrical cables, and a patient grounding plate. This generic type of device does not...

21 CFR 884.4160 - Unipolar endoscopic coagulator-cutter and accessories.

Code of Federal Regulations, 2013 CFR

2013-04-01

... temperatures by directing a high frequency electrical current through the tissue between an energized probe and... generator, probes and electrical cables, and a patient grounding plate. This generic type of device does not...

The Phosphorylation State of the Drosophila TRP Channel Modulates the Frequency Response to Oscillating Light In Vivo

PubMed Central

Rhodes-Mordov, Elisheva; Katz, Ben; Oberegelsbacher, Claudia; Yasin, Bushra; Tzadok, Hanan; Huber, Armin

2017-01-01

Drosophila photoreceptors respond to oscillating light of high frequency (∼100 Hz), while the detected maximal frequency is modulated by the light rearing conditions, thus enabling high sensitivity to light and high temporal resolution. However, the molecular basis for this adaptive process is unclear. Here, we report that dephosphorylation of the light-activated transient receptor potential (TRP) ion channel at S936 is a fast, graded, light-dependent, and Ca2+-dependent process that is partially modulated by the rhodopsin phosphatase retinal degeneration C (RDGC). Electroretinogram measurements of the frequency response to oscillating lights in vivo revealed that dark-reared flies expressing wild-type TRP exhibited a detection limit of oscillating light at relatively low frequencies, which was shifted to higher frequencies upon light adaptation. Strikingly, preventing phosphorylation of the S936-TRP site by alanine substitution in transgenic Drosophila (trpS936A) abolished the difference in frequency response between dark-adapted and light-adapted flies, resulting in high-frequency response also in dark-adapted flies. In contrast, inserting a phosphomimetic mutation by substituting the S936-TRP site to aspartic acid (trpS936D) set the frequency response of light-adapted flies to low frequencies typical of dark-adapted flies. Light-adapted rdgC mutant flies showed relatively high S936-TRP phosphorylation levels and light–dark phosphorylation dynamics. These findings suggest that RDGC is one but not the only phosphatase involved in pS936-TRP dephosphorylation. Together, this study indicates that TRP channel dephosphorylation is a regulatory process that affects the detection limit of oscillating light according to the light rearing condition, thus adjusting dynamic processing of visual information under varying light conditions. SIGNIFICANCE STATEMENT Drosophila photoreceptors exhibit high temporal resolution as manifested in frequency response to oscillating light of high frequency (≤∼100 Hz). Light rearing conditions modulate the maximal frequency detected by photoreceptors, thus enabling them to maintain high sensitivity to light and high temporal resolution. However, the precise mechanisms for this process are not fully understood. Here, we show by combination of biochemistry and in vivo electrophysiology that transient receptor potential (TRP) channel dephosphorylation at a specific site is a fast, light-activated and Ca2+-dependent regulatory process. TRP dephosphorylation affects the detection limit of oscillating light according to the adaptation state of the photoreceptor cells by shifting the detection limit to higher frequencies upon light adaptation. This novel mechanism thus adjusts dynamic processing of visual information under varying light conditions. PMID:28314815

Low-frequency variations of unknown origin in the Kepler δ Scuti star KIC 5988140 = HD 188774

NASA Astrophysics Data System (ADS)

Lampens, P.; Tkachenko, A.; Lehmann, H.; Debosscher, J.; Aerts, C.; Beck, P. G.; Bloemen, S.; Kochiashvili, N.; Derekas, A.; Smith, J. C.; Tenenbaum, P.; Twicken, J. D.

2013-01-01

Context. The NASA exoplanet search mission Kepler is currently providing a wealth of light curves of ultra-high quality from space. Aims: We used high-quality Kepler photometry and spectroscopic data to investigate the Kepler target and binary candidate KIC 5988140. We aim to interpret the observed variations of KIC 5988140 considering three possible scenarios: binarity, co-existence of δ Sct- and γ Dor-type oscillations, and rotational modulation caused by an asymmetric surface intensity distribution. Methods: We used the spectrum synthesis method to derive the fundamental parameters Teff, log g, [M/H], and v sin i from the newly obtained high-resolution, high S/N spectra. Frequency analyses of both the photometric and the spectroscopic data were performed. Results: The star has a spectral type of A7.5 IV-III and a metallicity slightly lower than that of the Sun. Both Fourier analyses reveal the same two dominant frequencies F1 = 2F2 = 0.688 and F2 = 0.344 d-1. We also detected in the photometry the signal of nine more, significant frequencies located in the typical range of δ Sct pulsation. The light and radial velocity curves follow a similar, stable double-wave pattern which are not exactly in anti-phase but show a relative phase shift of about 0.1 period between the moment of minimum velocity and that of maximum light. Conclusions: Such findings are incompatible with the star being a binary system. We next show that, for all possible (limit) configurations of a spotted surface, the predicted light-to-velocity amplitude ratio is almost two orders larger than the observed value, which pleads against rotational modulation. The same argument also invalidates the explanation in terms of pulsations of type γ Dor (i.e. hybrid pulsations). We confirm the occurrence of various independent δ Sct-type pressure modes in the Kepler light curve. With respect to the low-frequency content, however, we argue that the physical cause of the remaining light and radial velocity variations of this late A-type star remains unexplained by any of the presently considered scenarios. Based on data gathered with NASA's Discovery mission Kepler and with the Hermes spectrograph, installed at the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, and with the 2-m Alfred-Jensch telescope of the Thüringer Landessternwarte Tautenburg.Reduced spectra are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/549/A104

An investigation of hydraulic-line resonance and its attenuation

NASA Technical Reports Server (NTRS)

Sewall, J. L.; Wineman, D. A.; Herr, R. W.

1973-01-01

An investigation of fluid resonance in high-pressure hydraulic lines has been made with two types of fluid dampers (or filters) installed in the line. One type involved the use of one or more closed-end tubes branching at right angles from a main line, and the other type was a fluid muffler installed in-line. These devices were evaluated in forced vibration tests with oscillatory disturbances over a 1000-Hz range applied to one end of the line and with oscillatory pressures measured at various stations along the main pipe. Limited applications of acoustic-wave theory to the branched systems are also included. Results show varying attenuations of pressure perturbations, depending on the number and location of branches and the type of muffler. Up to three branches were used in the branch-resonator study, and the largest frequency range with maximum attenuation was obtained for a three-branch configuration. The widest frequency ranges with significant attenuations were obtained with two types of fluid mufflers.

Examining the profile of high-potency cannabis and its association with severity of cannabis dependence.

PubMed

Freeman, T P; Winstock, A R

2015-11-01

Cannabis use is decreasing in England and Wales, while demand for cannabis treatment in addiction services continues to rise. This could be partly due to an increased availability of high-potency cannabis. Adults residing in the UK were questioned about their drug use, including three types of cannabis (high potency: skunk; low potency: other grass, resin). Cannabis types were profiled and examined for possible associations between frequency of use and (i) cannabis dependence, (ii) cannabis-related concerns. Frequent use of high-potency cannabis predicted a greater severity of dependence [days of skunk use per month: b = 0.254, 95% confidence interval (CI) 0.161-0.357, p < 0.001] and this effect became stronger as age decreased (b = -0.006, 95% CI -0.010 to -0.002, p = 0.004). By contrast, use of low-potency cannabis was not associated with dependence (days of other grass use per month: b = 0.020, 95% CI -0.029 to 0.070, p = 0.436; days of resin use per month: b = 0.025, 95% CI -0.019 to 0.067, p = 0.245). Frequency of cannabis use (all types) did not predict severity of cannabis-related concerns. High-potency cannabis was clearly distinct from low-potency varieties by its marked effects on memory and paranoia. It also produced the best high, was preferred, and most available. High-potency cannabis use is associated with an increased severity of dependence, especially in young people. Its profile is strongly defined by negative effects (memory, paranoia), but also positive characteristics (best high, preferred type), which may be important when considering clinical or public health interventions focusing on cannabis potency.

Fine Structures of Solar Radio Type III Bursts and Their Possible Relationship with Coronal Density Turbulence

NASA Astrophysics Data System (ADS)

Chen, Xingyao; Kontar, Eduard P.; Yu, Sijie; Yan, Yihua; Huang, Jing; Tan, Baolin

2018-03-01

Solar radio type III bursts are believed to be the most sensitive signatures of near-relativistic electron beam propagation in the corona. A solar radio type IIIb-III pair burst with fine frequency structures, observed by the Low Frequency Array (LOFAR) with high temporal (∼10 ms) and spectral (12.5 kHz) resolutions at 30–80 MHz, is presented. The observations show that the type III burst consists of many striae, which have a frequency scale of about 0.1 MHz in both the fundamental (plasma) and the harmonic (double plasma) emission. We investigate the effects of background density fluctuations based on the observation of striae structure to estimate the density perturbation in the solar corona. It is found that the spectral index of the density fluctuation spectrum is about ‑1.7, and the characteristic spatial scale of the density perturbation is around 700 km. This spectral index is very close to a Kolmogorov turbulence spectral index of ‑5/3, consistent with a turbulent cascade. This fact indicates that the coronal turbulence may play the important role of modulating the time structures of solar radio type III bursts, and the fine structure of radio type III bursts could provide a useful and unique tool to diagnose the turbulence in the solar corona.

Circadian rhythm of autonomic activity in non diabetic offsprings of type 2 diabetic patients

PubMed Central

Fiorentini, A; Perciaccante, A; Paris, A; Serra, P; Tubani, L

2005-01-01

The aim of the present study was to evaluate, by heart rate variability (HRV) with 24-hours ECG Holter (HRV), the circadian autonomic activity in offspring of type 2 diabetic subjects and the relation with insulin-resistance. METHODS: 50 Caucasian offsprings of type 2 diabetic subjects were divided in two groups: insulin-resistant offsprings (IR) and non insulin-resistant offsprings (NIR). Autonomic nervous activity was studied by HRV. Time domain and spectral analysis (low frequency, LF, and high frequency, HF, provide markers of sympathetic and parasympathetic modulation when assessed in normalized units) were evaluated. RESULTS. Time domain showed a reduction of total SDNN in IR (p < 0.001) and NIR (p 0.047) versus controls. Spectral analysis showed a total and night LF higher in IR and NIR than in control group (all p < 0.001). CONCLUSION. In frequency domain, the analysis of sympathetic (LF) and parasympathetic (HF) component evidenced an association between the offspring of type 2 diabetic subjects and a sympathetic overactivity. A global reduction and alteration of circadian rhythm of autonomic activity are present in offspring of type 2 diabetic patients with and without insulin resistance. The data of our study suggested that an autonomic impairment is associated with the familiarity for type 2 diabetes independently to insulin resistance and that an impairment of autonomic system activity could precede the insulin resistance. PMID:16197556

Regular Breakfast Consumption and Type 2 Diabetes Risk Markers in 9- to 10-Year-Old Children in the Child Heart and Health Study in England (CHASE): A Cross-Sectional Analysis

PubMed Central

Donin, Angela S.; Nightingale, Claire M.; Owen, Chris G.; Rudnicka, Alicja R.; Perkin, Michael R.; Jebb, Susan A.; Stephen, Alison M.; Sattar, Naveed; Cook, Derek G.; Whincup, Peter H.

2014-01-01

Background Regular breakfast consumption may protect against type 2 diabetes risk in adults but little is known about its influence on type 2 diabetes risk markers in children. We investigated the associations between breakfast consumption (frequency and content) and risk markers for type 2 diabetes (particularly insulin resistance and glycaemia) and cardiovascular disease in children. Methods and Findings We conducted a cross-sectional study of 4,116 UK primary school children aged 9–10 years. Participants provided information on breakfast frequency, had measurements of body composition, and gave fasting blood samples for measurements of blood lipids, insulin, glucose, and glycated haemoglobin (HbA1c). A subgroup of 2,004 children also completed a 24-hour dietary recall. Among 4,116 children studied, 3,056 (74%) ate breakfast daily, 450 (11%) most days, 372 (9%) some days, and 238 (6%) not usually. Graded associations between breakfast frequency and risk markers were observed; children who reported not usually having breakfast had higher fasting insulin (percent difference 26.4%, 95% CI 16.6%–37.0%), insulin resistance (percent difference 26.7%, 95% CI 17.0%–37.2%), HbA1c (percent difference 1.2%, 95% CI 0.4%–2.0%), glucose (percent difference 1.0%, 95% CI 0.0%–2.0%), and urate (percent difference 6%, 95% CI 3%–10%) than those who reported having breakfast daily; these differences were little affected by adjustment for adiposity, socioeconomic status, and physical activity levels. When the higher levels of triglyceride, systolic blood pressure, and C-reactive protein for those who usually did not eat breakfast relative to those who ate breakfast daily were adjusted for adiposity, the differences were no longer significant. Children eating a high fibre cereal breakfast had lower insulin resistance than those eating other breakfast types (p for heterogeneity <0.01). Differences in nutrient intakes between breakfast frequency groups did not account for the differences in type 2 diabetes markers. Conclusions Children who ate breakfast daily, particularly a high fibre cereal breakfast, had a more favourable type 2 diabetes risk profile. Trials are needed to quantify the protective effect of breakfast on emerging type 2 diabetes risk. Please see later in the article for the Editors' Summary PMID:25181492

Statistical studies of superflares on G-, K-, M- type stars from Kepler data

NASA Astrophysics Data System (ADS)

Notsu, Yuta; Maehara, Hiroyuki; Honda, Satoshi; Notsu, Shota; Namekata, Kosuke; Ikuta, Kai; Nogami, Daisaku; Shibata, Kazunari

2017-05-01

Flares are thought to be sudden releases of magnetic energy stored around starspots. Recent space high-precision photometry shows “superflares”, 10-104 times more energetic than the largest solar flares, occur on many G, K, M-type stars (e.g., Maehara+2012 Nature). Harmful UV/X-ray radiation and high-energy particles such as protons are caused by such superflares. This may suggest that exoplanet host stars have severe effects on the physical and chemical evolution of exoplanetary atmospheres (cf. Segura+2010 Astrobiology, Takahashi+2016 ApJL).We here present statistical properties of superflares on G, K, M-type stars on the basis of our analyses of Kepler photometric data (Maehara+2012 Nature, Shibayama+2013 ApJS, Notsu+2013 ApJ, Canderaresi+2014 ApJ, Maehara+2015 EPS, Maehara+2017 PASJ). We found more than 5000 superflares on 800 G, K, M-type main-sequence stars, and the occurrence frequency (dN/dE) of superflares as a function of flare energy (E) shows the power-law distribution with the index of -1.8 -1.9. This power-law distribution is consistent with that of solar flares.Flare frequency increases as stellar temperature decreases. As for M-type stars, energy of the largest flares is smaller compared with G,K-type stars, but more frequent “hazardous” flares for the habitable planets since the habitable zone around M-type stars is much smaller compared with G, K-type stars.Rotation period and starspot coverage can be estimated from the quasi-periodic brightness variation of the superflare stars. The intensity of Ca II 8542 line of superflare stars, which is measured from spectroscopic observations with Subaru Telescope, has a well correlation with the brightness variation amplitude (Notsu+2015a&b PASJ).Flare frequency has a correlation with rotation period, and this suggests young rapidly-rotating stars (like “young Sun”) have more severe impacts of flares on the planetary atmosphere (cf. Airapetian+2016 ApJL). Flare energy and frequency also depends on starspot coverage, and this suggests existence of large starspots is important factor of superflares.These statistical properties of superflares discussed here can be one of the basic information for considering the impacts of flares on planet-host stars.

Optical Sidebands Multiplier

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry V.; Yu, Nan

2010-01-01

Optical sidebands have been generated with relative frequency tens to hundreds of GHz by using optical sidebands that are generated in a cascade process in high-quality optical resonators with Kerr nonlinearity, such as whispering gallery mode (WGM) resonators. For this purpose, the WGM resonator needs to be optically pumped at two frequencies matching its resonances. These two optical components can be one or several free spectral ranges (FSRs), equal to approximately 12 GHz, in this example, apart from each other, and can be easily derived from a monochromatic pump with an ordinary EOM (electro-optic modulation) operating at half the FSR frequency. With sufficient nonlinearity, an optical cascade process will convert the two pump frequencies into a comb-like structure extending many FSRs around the carrier frequency. This has a demonstratively efficient frequency conversion of this type with only a few milliwatt optical pump power. The concept of using Kerr nonlinearity in a resonator for non-degenerate wave mixing has been discussed before, but it was a common belief that this was a weak process requiring very high peak powers to be observable. It was not thought possible for this approach to compete with electro-optical modulators in CW applications, especially those at lower optical powers. By using the high-Q WGM resonators, the effective Kerr nonlinearity can be made so high that, using even weak seeding bands available from a conventional EOM, one can effectively multiply the optical sidebands, extending them into an otherwise inaccessible frequency range.

Ca currents activated by spontaneous firing and synaptic disinhibition in neurons of the cerebellar nuclei

PubMed Central

Zheng, Nan; Raman, Indira M.

2009-01-01

In neurons of the cerebellar nuclei, long-term potentiation of EPSCs is induced by high-frequency synaptic excitation by mossy fibers followed by synaptic inhibition by Purkinje cells. Induction requires activation of synaptic receptors as well as voltage-gated Ca channels. To examine how Purkinje-mediated inhibition of nuclear neurons affects Ca levels during plasticity-inducing stimuli, we have combined electrophysiology, Ca imaging, and pharmacology of cerebellar nuclear neurons in mouse cerebellar slices. We find that spontaneous firing generates tonic Ca signals in both somata and dendrites, which drop during 500-ms, 100-Hz trains of Purkinje IPSPs or hyperpolarizing steps. Although the presence of low-voltage-activated (T-type) Ca channels in nuclear neurons has fostered the inference that disinhibition activates these channels, synaptic inhibition with a physiological ECl (−75 mV) fails to hyperpolarize neurons sufficiently for T-type channels to recover substantially. Consequently, after IPSPs, Ca signals return to baseline, although firing is accelerated by ∼20 Hz for ∼300 ms. Only after hyperpolarizations beyond ECl does Ca rise gradually beyond baseline, as firing further exceeds spontaneous rates. Cd2+ (100 μM), which nearly eliminates L-type, N-type, P/Q-type, and R-type Ca currents while sparing about half the T-type current, prevents Ca changes during and after hyperpolarizations to ECl. Thus, high-frequency IPSPs in cerebellar nuclear neurons evoke little post-inhibitory current through T-type channels. Instead, inhibition regulates Ca levels simply by preventing action potentials, which usually permit Ca influx through high-voltage-activated channels. The decreases and restoration of Ca levels associated with Purkinje-mediated inhibition are likely to contribute to synaptic plasticity. PMID:19657035

Variations in Daily Sleep Quality and Type 1 Diabetes Management in Late Adolescents

PubMed Central

Queen, Tara L.; Butner, Jonathan; Wiebe, Deborah; Berg, Cynthia A.

2016-01-01

Objective To determine how between- and within-person variability in perceived sleep quality were associated with adolescent diabetes management. Methods A total of 236 older adolescents with type 1 diabetes reported daily for 2 weeks on sleep quality, self-regulatory failures, frequency of blood glucose (BG) checks, and BG values. Average, inconsistent, and daily deviations in sleep quality were examined. Results Hierarchical linear models indicated that poorer average and worse daily perceived sleep quality (compared with one’s average) was each associated with more self-regulatory failures. Sleep quality was not associated with frequency of BG checking. Poorer average sleep quality was related to greater risk of high BG. Furthermore, inconsistent and daily deviations in sleep quality interacted to predict higher BG, with more consistent sleepers benefitting more from a night of high-quality sleep. Conclusions Good, consistent sleep quality during late adolescence may benefit diabetes management by reducing self-regulatory failures and risk of high BG. PMID:26994852

High-frequency dual mode pulsed wave Doppler imaging for monitoring the functional regeneration of adult zebrafish hearts

PubMed Central

Kang, Bong Jin; Park, Jinhyoung; Kim, Jieun; Kim, Hyung Ham; Lee, Changyang; Hwang, Jae Youn; Lien, Ching-Ling; Shung, K. Kirk

2015-01-01

Adult zebrafish is a well-known small animal model for studying heart regeneration. Although the regeneration of scars made by resecting the ventricular apex has been visualized with histological methods, there is no adequate imaging tool for tracking the functional recovery of the damaged heart. For this reason, high-frequency Doppler echocardiography using dual mode pulsed wave Doppler, which provides both tissue Doppler (TD) and Doppler flow in a same cardiac cycle, is developed with a 30 MHz high-frequency array ultrasound imaging system. Phantom studies show that the Doppler flow mode of the dual mode is capable of measuring the flow velocity from 0.1 to 15 cm s−1 with high accuracy (p-value = 0.974 > 0.05). In the in vivo study of zebrafish, both TD and Doppler flow signals were simultaneously obtained from the zebrafish heart for the first time, and the synchronized valve motions with the blood flow signals were identified. In the longitudinal study on the zebrafish heart regeneration, the parameters for diagnosing the diastolic dysfunction, for example, E/Em < 10, E/A < 0.14 for wild-type zebrafish, were measured, and the type of diastolic dysfunction caused by the amputation was found to be similar to the restrictive filling. The diastolic function was fully recovered within four weeks post-amputation. PMID:25505135

Use of PCR with Sequence-specific Primers for High-Resolution Human Leukocyte Antigen Typing of Patients with Narcolepsy

PubMed Central

Woo, Hye In; Joo, Eun Yeon; Lee, Kyung Wha

2012-01-01

Background Narcolepsy is a neurologic disorder characterized by excessive daytime sleepiness, symptoms of abnormal rapid eye movement (REM) sleep, and a strong association with HLA-DRB1*1501, -DQA1*0102, and -DQB1*0602. Here, we investigated the clinico-physical characteristics of Korean patients with narcolepsy, their HLA types, and the clinical utility of high-resolution PCR with sequence-specific primers (PCR-SSP) as a simple typing method for identifying DRB1*15/16, DQA1, and DQB1 alleles. Methods The study population consisted of 67 consecutively enrolled patients having unexplained daytime sleepiness and diagnosed narcolepsy based on clinical and neurological findings. Clinical data and the results of the multiple sleep latency test and polysomnography were reviewed, and HLA typing was performed using both high-resolution PCR-SSP and sequence-based typing (SBT). Results The 44 narcolepsy patients with cataplexy displayed significantly higher frequencies of DRB1*1501 (Pc= 0.003), DQA1*0102 (Pc=0.001), and DQB1*0602 (Pc=0.014) than the patients without cataplexy. Among patients carrying DRB1*1501-DQB1*0602 or DQA1*0102, the frequencies of a mean REM sleep latency of less than 20 min in nocturnal polysomnography and clinical findings, including sleep paralysis and hypnagogic hallucination were significantly higher. SBT and PCR-SSP showed 100% concordance for high-resolution typing of DRB1*15/16 alleles and DQA1 and DQB1 loci. Conclusions The clinical characteristics and somnographic findings of narcolepsy patients were associated with specific HLA alleles, including DRB1*1501, DQA1*0102, and DQB1*0602. Application of high-resolution PCR-SSP, a reliable and simple method, for both allele- and locus-specific HLA typing of DRB1*15/16, DQA1, and DQB1 would be useful for characterizing clinical status among subjects with narcolepsy. PMID:22259780

Piezoelectric Instruments of High Natural Frequency Vibration Characteristics and Protection Against Interference by Mass Forces

NASA Technical Reports Server (NTRS)

Gohlka, Werner

1943-01-01

The exploration of the processes accompanying engine combustion demands quick-responding pressure-recording instruments, among which the piezoelectric type has found widespread use because of its especially propitious properties as vibration-recording instruments for high frequencies. Lacking appropriate test methods, the potential errors of piezoelectric recorders in dynamic measurements could only be estimated up to now. In the present report a test method is described by means of which the resonance curves of the piezoelectric pickup can be determined; hence an instrumental appraisal of the vibration characteristics of piezoelectric recorders is obtainable.

Heart Rate Variability Indexes in Dementia: A Systematic Review with a Quantitative Analysis.

PubMed

da Silva, Vanessa Pereira; Ramalho Oliveira, Bruno Ribeiro; Tavares Mello, Roger Gomes; Moraes, Helena; Deslandes, Andrea Camaz; Laks, Jerson

2018-01-01

Decreased heart rate variability (HRV) indexes indicate low vagal activity and may be associated with development of dementia. The neurodegenerative process is associated with the cardiovascular autonomic control. The aim of this systematic review was to investigate the effect size (ES) magnitude of the HRV indexes in the evaluation of autonomic dysfunction in older persons with dementia. PubMed (Medline), Web of Science, Scopus, Scielo, Lilacs, and APA Psycnet were consulted. Complete original articles published in English or Portuguese, investigating the association between autonomic dysfunction and dementia, using the HRV indexes were included. The search identified 97 potentially relevant articles. After screening the full text, eight articles were included in the qualitative analysis and six were included in the quantitative analysis. Almost all indexes showed a negative ES for all types of dementia and mild cognitive impairment. The most common frequency band of the power spectrum density function was the high frequency, which was reported by six studies. The meta-analysis of high frequency power in Alzheimer's disease group showed high heterogeneity and inconsistent results. The negative effect size suggests an autonomic dysfunction in all types of dementia as well as mild cognitive impairment. However, further analysis is necessary to support these results. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

A systematic and efficient method for modeling acoustic response of multilayered media

NASA Astrophysics Data System (ADS)

Feng, Shi-Jin; Chen, Zhang-Long; Chen, Hong-Xin

2017-12-01

A generalized transmission and reflection matrix (GTRM) method for determining the acoustic response of multilayered media is developed in this paper. The principle of the method is to decipher the wave vectors by constructing generalized T/R matrices and recursive formulas. The generalized T/R matrices are introduced to account for the contributions of multiple reflection and transmission in a global manner. Three types of interface T/R matrices are developed to accommodate the coupling between any type of physical medium. This method is not only stable for high-frequency and large thickness cases by excluding the growing terms but also explicitly exhibits the physical mechanism of wave propagation. Acoustic response in both frequency and time domains can be solved by the method. Moreover, the method has a simple framework, and it is easy to be implemented in numerical tools. The method is successfully validated by several typical acoustic problems, including poroelastic medium immersed in fluid, aluminum-glass-aluminum immersed in fluid, and poroelastic sediment sandwiched between water and bedrock. In fact, the present method can be extended to any physical problem of a multilayered structure. When the wave frequency is high or the layered media is greatly thick or the material combination is highly complex, the advantage of the GTRM method is more conspicuous.

Inertial Response of Wind Power Plants: A Comparison of Frequency-Based Inertial Control and Stepwise Inertial Control

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

Wang, Xiao; Gao, Wenzhong; Wang, Jianhui

The frequency regulation capability of a wind power plant plays an important role in enhancing frequency reliability especially in an isolated power system with high wind power penetration levels. A comparison of two types of inertial control methods, namely frequency-based inertial control (FBIC) and stepwise inertial control (SIC), is presented in this paper. Comprehensive case studies are carried out to reveal features of the different inertial control methods, simulated in a modified Western System Coordination Council (WSCC) nine-bus power grid using real-time digital simulator (RTDS) platform. The simulation results provide an insight into the inertial control methods under various scenarios.

Monazite-type SrCr O 4 under compression

DOE PAGES

Gleissner, J.; Errandonea, Daniel; Segura, A.; ...

2016-10-20

We report a high-pressure study of monoclinic monazite-type SrCrO 4 up to 26 GPa. Therein we combined x-ray diffraction, Raman, and optical-absorption measurements with ab initio calculations, to find a pressure-induced structural phase transition of SrCrO 4 near 8-9 GPa. Evidence of a second phase transition was observed at 10-13 GPa. The crystal structures of the high-pressure phases were assigned to the tetragonal scheelite-type and monoclinic AgMnO 4-type structures. Both transitions produce drastic changes in the electronic band gap and phonon spectrum of SrCrO 4. We determined the pressure evolution of the band gap for the low- and high-pressure phasesmore » as well as the frequencies and pressure dependencies of the Raman-active modes. In all three phases most Raman modes harden under compression, however the presence of low-frequency modes which gradually soften is also detected. In monazite-type SrCrO 4, the band gap blueshifts under compression, but the transition to the scheelite phase causes an abrupt decrease of the band gap in SrCrO 4. Calculations showed good agreement with experiments and were used to better understand the experimental results. From x-ray-diffraction studies and calculations we determined the pressure dependence of the unit-cell parameters of the different phases and their ambient-temperature equations of state. The results are compared with the high-pressure behavior of other monazites, in particular PbCrO 4. A comparison of the high-pressure behavior of the electronic properties of SrCrO 4 (SrWO 4) and PbCrO 4 (PbWO 4) will also be made. Lastly, the possible occurrence of a third structural phase transition is discussed.« less

Ground Radar Polarimetric Observations of High-Frequency Earth-Space Communication Links

NASA Technical Reports Server (NTRS)

Bolen, Steve; Chandrasekar, V.; Benjamin, Andrew

2002-01-01

Strategic roadmaps for NASA's Human Exploration and Development of Space (REDS) enterprise support near-term high-frequency communication systems that provide moderate to high data rates with dependable service. Near-earth and human planetary exploration will baseline Ka-Band, but may ultimately require the use of even higher frequencies. Increased commercial demand on low-frequency earth-space bands has also led to increased interest in the use of higher frequencies in regions like K u - and K,- band. Data is taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), which operates at 13.8 GHz, and the true radar reflectivity profile is determined along the PR beam via low-frequency ground based polarimetric observations. The specific differential phase (Kdp) is measured along the beam and a theoretical model is used to determine the expected specific attenuation (k). This technique, called the k-Kdp method, uses a Fuzzy-Logic model to determine the hydrometeor type along the PR beam from which the appropriate k-Kdp relationship is used to determine k and, ultimately, the total path-integrated attenuation (PIA) on PR measurements. Measurements from PR and the NCAR S-POL radar were made during the TEFLUN-B experiment that took place near Melbourne, FL in 1998, and the TRMM-LBA campaign near Ji-Parana, Brazil in 1999.

A novel x-ray detector design with higher DQE and reduced aliasing: Theoretical analysis of x-ray reabsoprtion in detector converter material

NASA Astrophysics Data System (ADS)

Nano, Tomi; Escartin, Terenz; Karim, Karim S.; Cunningham, Ian A.

2016-03-01

The ability to improve visualization of structural information in digital radiography without increasing radiation exposures requires improved image quality across all spatial frequencies, especially at high frequencies. The detective quantum efficiency (DQE) as a function of spatial frequency quantifies image quality given by an x-ray detector. We present a method of increasing DQE at high spatial frequencies by improving the modulation transfer function (MTF) and reducing noise aliasing. The Apodized Aperature Pixel (AAP) design uses a detector with micro-elements to synthesize desired pixels and provide higher DQE than conventional detector designs. A cascaded system analysis (CSA) that incorporates x-ray interactions is used for comparison of the theoretical MTF, noise power spectrum (NPS), and DQE. Signal and noise transfer through the converter material is shown to consist of correlated an uncorrelated terms. The AAP design was shown to improve the DQE of both material types that have predominantly correlated transfer (such as CsI) and predominantly uncorrelated transfer (such as Se). Improvement in the MTF by 50% and the DQE by 100% at the sampling cut-off frequency is obtained when uncorrelated transfer is prevalent through the converter material. Optimizing high-frequency DQE results in improved image contrast and visualization of small structures and fine-detail.

Associations Between E-Cigarette Type, Frequency of Use, and Quitting Smoking: Findings From a Longitudinal Online Panel Survey in Great Britain

PubMed Central

Brose, Leonie S.; Brown, Jamie; Robson, Debbie; McNeill, Ann

2015-01-01

Introduction: E-cigarettes can be categorized into two basic types, (1) cigalikes, that are disposable or use pre-filled cartridges and (2) tanks, that can be refilled with liquids. The aims of this study were to examine: (1) predictors of using the two e-cigarette types, and (2) the association between type used, frequency of use (daily vs. non-daily vs. no use), and quitting. Methods: Online longitudinal survey of smokers in Great Britain was first conducted in November 2012. Of 4064 respondents meeting inclusion criteria at baseline, this study included (N = 1643) current smokers followed-up 1 year later. Type and frequency of e-cigarette use were measured at follow-up. Results: At follow-up, 64% reported no e-cigarette use, 27% used cigalikes, and 9% used tanks. Among e-cigarette users at follow-up, respondents most likely to use tanks versus cigalikes included: 40–54 versus 18–24 year olds and those with low versus moderate/high education. Compared to no e-cigarette use at follow-up, non-daily cigalike users were less likely to have quit smoking since baseline (P = .0002), daily cigalike or non-daily tank users were no more or less likely to have quit (P = .3644 and P = .4216, respectively), and daily tank users were more likely to have quit (P = .0012). Conclusions: Whether e-cigarette use is associated with quitting depends on type and frequency of use. Compared with respondents not using e-cigarettes, daily tank users were more likely, and non-daily cigalike users were less likely, to have quit. Tanks were more likely to be used by older respondents and respondents with lower education. PMID:25896067

Discharge Characteristics of DC Arc Water Plasma for Environmental Applications

NASA Astrophysics Data System (ADS)

Li, Tianming; Sooseok, Choi; Takayuki, Watanabe

2012-12-01

A water plasma was generated by DC arc discharge with a hafnium embedded rod-type cathode and a nozzle-type anode. The discharge characteristics were examined by changing the operation parameter of the arc current. The dynamic behavior of the arc discharge led to significant fluctuations in the arc voltage and its frequency. Analyses of the high speed image and the arc voltage waveform showed that the arc discharge was in the restrike mode and its frequency varied within several tens of kilohertz according to the operating conditions. The larger thermal plasma volume was generated by the higher flow from the forming steam with a higher restrike frequency in the higher arc current conditions. In addition, the characteristics of the water plasma jet were investigated by means of optical emission spectroscopy to identify the abundant radicals required in an efficient waste treatment process.

Distance measurements in Au nanoparticles functionalized with nitroxide radicals and Gd(3+)-DTPA chelate complexes.

PubMed

Yulikov, Maxim; Lueders, Petra; Warsi, Muhammad Farooq; Chechik, Victor; Jeschke, Gunnar

2012-08-14

Nanosized gold particles were functionalised with two types of paramagnetic surface tags, one having a nitroxide radical and the other one carrying a DTPA complex loaded with Gd(3+). Selective measurements of nitroxide-nitroxide, Gd(3+)-nitroxide and Gd(3+)-Gd(3+) distances were performed on this system and information on the distance distribution in the three types of spin pairs was obtained. A numerical analysis of the dipolar frequency distributions is presented for Gd(3+) centres with moderate magnitudes of zero-field splitting, in the range of detection frequencies and resonance fields where the high-field approximation is only roughly valid. The dipolar frequency analysis confirms the applicability of DEER for distance measurements in such complexes and gives an estimate for the magnitudes of possible systematic errors due to the non-ideality of the measurement of the dipole-dipole interaction.

Communication: Helium nanodroplet isolation and rovibrational spectroscopy of hydroxymethylene

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

Leavitt, Christopher M.; Moradi, Christopher P.; Stanton, John F.

Here, hydroxymethylene (HCOH) and its d 1-isotopologue (HCOD) are isolated in low temperature helium nanodroplets following pyrolysis of glyoxylic acid. Transitions identified in the infrared spectrum are assigned exclusively to the trans-conformation based on previously reported anharmonic frequency computations. For the OH(D) and CH stretches, a-and b-type transitions are observed, and when taken in conjunction with CCSD(T)/cc-pVTZ computations, lower limits to the vibrational band origins are determined. The relative intensities of the a-and b-type transitions provide the orientation of the transition dipole moment in the inertial frame. The He nanodroplet data are in excellent agreement with anharmonic frequency computations reportedmore » here and elsewhere, confirming an appreciable Ar-matrix shift of the OH and OD stretches and strong anharmonic resonance interactions in the high-frequency stretch regions of the mid-infrared.« less

Communication: Helium nanodroplet isolation and rovibrational spectroscopy of hydroxymethylene

DOE PAGES

Leavitt, Christopher M.; Moradi, Christopher P.; Stanton, John F.; ...

2014-05-05

Here, hydroxymethylene (HCOH) and its d 1-isotopologue (HCOD) are isolated in low temperature helium nanodroplets following pyrolysis of glyoxylic acid. Transitions identified in the infrared spectrum are assigned exclusively to the trans-conformation based on previously reported anharmonic frequency computations. For the OH(D) and CH stretches, a-and b-type transitions are observed, and when taken in conjunction with CCSD(T)/cc-pVTZ computations, lower limits to the vibrational band origins are determined. The relative intensities of the a-and b-type transitions provide the orientation of the transition dipole moment in the inertial frame. The He nanodroplet data are in excellent agreement with anharmonic frequency computations reportedmore » here and elsewhere, confirming an appreciable Ar-matrix shift of the OH and OD stretches and strong anharmonic resonance interactions in the high-frequency stretch regions of the mid-infrared.« less

An investigation of the effects of pitch-roll (de)-coupling on helicopter handling qualities

NASA Technical Reports Server (NTRS)

Ockier, C. J.; Pausder, H. J.; Blanken, C. L.

1995-01-01

An investigation of the effects of pitch-roll coupling on helicopter handling qualities was performed by the US Army and DLR, using a NASA ground-based and a DLR inflight simulator. Over 90 different coupling configurations were evaluated using a roll-axis tracking task. The results show that although the current ADS-33C coupling criterion discriminates against those types of coupling typical of conventionally controlled helicopters, it not always suited for the prediction of handling qualities of helicopters with modern control systems. Based on the observation that high frequency inputs during tracking are used to alleviate coupling, a frequency domain pitch-roll coupling criterion that uses the average coupling ratio between the bandwidth and neutral stability frequency is formulated. This criterion provides a more comprehensive coverage with respect to the different types of coupling and shows excellent consistency.

Rare earth doped M-type hexaferrites; ferromagnetic resonance and magnetization dynamics

NASA Astrophysics Data System (ADS)

Sharma, Vipul; Kumari, Shweta; Kuanr, Bijoy K.

2018-05-01

M-type hexagonal barium ferrites come in the category of magnetic material that plays a key role in electromagnetic wave propagation in various microwave devices. Due to their large magnetic anisotropy and large magnetization, their operating frequency exceeds above 50 GHz. Doping is a way to vary its magnetic properties to such an extent that its ferromagnetic resonance (FMR) response can be tuned over a broad frequency band. We have done a complete FMR study of rare earth elements neodymium (Nd) and samarium (Sm), with cobalt (Co) as base, doped hexaferrite nanoparticles (NPs). X-ray diffractometry, vibrating sample magnetometer (VSM), and ferromagnetic resonance (FMR) techniques were used to characterize the microstructure and magnetic properties of doped hexaferrite nanoparticles. Using proper theoretical electromagnetic models, various parameters are extracted from FMR data which play important role in designing and fabricating high-frequency microwave devices.

Dielectric constants of soils at microwave frequencies-2

NASA Technical Reports Server (NTRS)

Wang, J.; Schmugge, T.; Williams, D.

1978-01-01

The dielectric constants of several soil samples were measured at frequencies of 5 and 19 GHz using the infinite transmission line method. The results of these measurements are presented and discussed with respect to soil types and texture structures. A comparison is made with other measurements at 1.4 GHz. At all three frequencies, the dependence of dielectric constant on soil moisture can be approximated by two straight lines. At low moisture, the slope is less than at high moisture level. The intersection of the two lines is believed to be a function of soil texture.

Oversampling in virtual visual sensors as a means to recover higher modes of vibration

NASA Astrophysics Data System (ADS)

Shariati, Ali; Schumacher, Thomas

2015-03-01

Vibration-based structural health monitoring (SHM) techniques require modal information from the monitored structure in order to estimate the location and severity of damage. Natural frequencies also provide useful information to calibrate finite element models. There are several types of physical sensors that can measure the response over a range of frequencies. For most of those sensors however, accessibility, limitation of measurement points, wiring, and high system cost represent major challenges. Recent optical sensing approaches offer advantages such as easy access to visible areas, distributed sensing capabilities, and comparatively inexpensive data recording while having no wiring issues. In this research we propose a novel methodology to measure natural frequencies of structures using digital video cameras based on virtual visual sensors (VVS). In our initial study where we worked with commercially available inexpensive digital video cameras we found that for multiple degrees of freedom systems it is difficult to detect all of the natural frequencies simultaneously due to low quantization resolution. In this study we show how oversampling enabled by the use of high-end high-frame-rate video cameras enable recovering all of the three natural frequencies from a three story lab-scale structure.

Frequency-tuned microwave photon counter based on a superconductive quantum interferometer

NASA Astrophysics Data System (ADS)

Shnyrkov, V. I.; Yangcao, Wu; Soroka, A. A.; Turutanov, O. G.; Lyakhno, V. Yu.

2018-03-01

Various types of single-photon counters operating in infrared, ultraviolet, and optical wavelength ranges are successfully used to study electromagnetic fields, analyze radiation sources, and solve problems in quantum informatics. However, their operating principles become ineffective at millimeter band, S-band, and ultra-high frequency bands of wavelengths due to the decrease in quantum energy by 4-5 orders of magnitude. Josephson circuits with discrete Hamiltonians and qubits are a good foundation for the construction of single-photon counters at these frequencies. This paper presents a frequency-tuned microwave photon counter based on a single-junction superconducting quantum interferometer and flux qutrit. The control pulse converts the interferometer into a two-level system for resonance absorption of photons. Decay of the photon-induced excited state changes the magnetic flux in the interferometer, which is measured by a SQUID magnetometer. Schemes for recording the magnetic flux using a DC SQUID or ideal parametric detector, based on a qutrit with high-frequency excitation, are discussed. It is shown that the counter consisting of an interferometer with a Josephson junction and a parametric detector demonstrates high performance and is capable of detecting single photons in a microwave band.

Towards high frequency heterojunction transistors: Electrical characterization of N-doped amorphous silicon-graphene diodes

NASA Astrophysics Data System (ADS)

Strobel, C.; Chavarin, C. A.; Kitzmann, J.; Lupina, G.; Wenger, Ch.; Albert, M.; Bartha, J. W.

2017-06-01

N-type doped amorphous hydrogenated silicon (a-Si:H) is deposited on top of graphene (Gr) by means of very high frequency (VHF) and radio frequency plasma-enhanced chemical vapor deposition (PECVD). In order to preserve the structural integrity of the monolayer graphene, a plasma excitation frequency of 140 MHz was successfully applied during the a-Si:H VHF-deposition. Raman spectroscopy results indicate the absence of a defect peak in the graphene spectrum after the VHF-PECVD of (n)-a-Si:H. The diode junction between (n)-a-Si:H and graphene was characterized using temperature dependent current-voltage (IV) and capacitance-voltage measurements, respectively. We demonstrate that the current at the (n)-a-Si:H-graphene interface is dominated by thermionic emission and recombination in the space charge region. The Schottky barrier height (qΦB), derived by temperature dependent IV-characteristics, is about 0.49 eV. The junction properties strongly depend on the applied deposition method of (n)-a-Si:H with a clear advantage of the VHF(140 MHz)-technology. We have demonstrated that (n)-a-Si:H-graphene junctions are a promising technology approach for high frequency heterojunction transistors.

A Solar Stationary Type IV Radio Burst and Its Radiation Mechanism

NASA Astrophysics Data System (ADS)

Liu, Hongyu; Chen, Yao; Cho, Kyungsuk; Feng, Shiwei; Vasanth, Veluchamy; Koval, Artem; Du, Guohui; Wu, Zhao; Li, Chuanyang

2018-04-01

A stationary Type IV (IVs) radio burst was observed on September 24, 2011. Observations from the Nançay RadioHeliograph (NRH) show that the brightness temperature (TB) of this burst is extremely high, over 10^{11} K at 150 MHz and over 108 K in general. The degree of circular polarization (q) is between -60% ˜ -100%, which means that it is highly left-handed circularly polarized. The flux-frequency spectrum follows a power-law distribution, and the spectral index is considered to be roughly -3 ˜ -4 throughout the IVs. Radio sources of this event are located in the wake of the coronal mass ejection and are spatially dispersed. They line up to present a formation in which lower-frequency sources are higher. Based on these observations, it is suggested that the IVs was generated through electron cyclotron maser emission.

High-frequency ultrasound-guided disruption of glycoprotein VI-targeted microbubbles targets atheroprogressison in mice.

PubMed

Metzger, Katja; Vogel, Sebastian; Chatterjee, Madhumita; Borst, Oliver; Seizer, Peter; Schönberger, Tanja; Geisler, Tobias; Lang, Florian; Langer, Harald; Rheinlaender, Johannes; Schäffer, Tilman E; Gawaz, Meinrad

2015-01-01

Targeted contrast-enhanced ultrasound (CEU) using microbubble agents is a promising non-invasive imaging technique to evaluate atherosclerotic lesions. In this study, we decipher the diagnostic and therapeutic potential of targeted-CEU with soluble glycoprotein (GP)-VI in vivo. Microbubbles were conjugated with the recombinant fusion protein GPVI-Fc (MBGPVI) that binds with high affinity to atherosclerotic lesions. MBGPVI or control microbubbles (MBC) were intravenously administered into ApoE(-/-) or wild type mice and binding of the microbubbles to the vessel wall was visualized by high-resolution CEU. CEU molecular imaging signals of MBGPVI were substantially enhanced in the aortic arch and in the truncus brachiocephalicus in ApoE(-/-) as compared to wild type mice. High-frequency ultrasound (HFU)-guided disruption of MBGPVI enhanced accumulation of GPVI in the atherosclerotic lesions, which may interfere with atheroprogression. Thus, we establish targeted-CEU with soluble GPVI as a novel non-invasive molecular imaging method for atherosclerosis. Further, HFU-guided disruption of GPVI-targeted microbubbles is an innovate therapeutic approach that potentially prevents progression of atherosclerotic disease. Copyright © 2014 Elsevier Ltd. All rights reserved.

A comparison of freeway median crash frequency, severity, and barrier strike outcomes by median barrier type.

PubMed

Russo, Brendan J; Savolainen, Peter T

2018-08-01

Median-crossover crashes are among the most hazardous events that can occur on freeways, often resulting in severe or fatal injuries. The primary countermeasure to reduce the occurrence of such crashes is the installation of a median barrier. When installation of a median barrier is warranted, transportation agencies are faced with the decision among various alternatives including concrete barriers, beam guardrail, or high-tension cable barriers. Each barrier type differs in terms of its deflection characteristics upon impact, the required installation and maintenance costs, and the roadway characteristics (e.g., median width) where installation would be feasible. This study involved an investigation of barrier performance through an in-depth analysis of crash frequency and severity data from freeway segments where high-tension cable, thrie-beam, and concrete median barriers were installed. A comprehensive manual review of crash reports was conducted to identify crashes in which a vehicle left the roadway and encroached into the median. This review also involved an examination of crash outcomes when a barrier strike occurred, which included vehicle containment, penetration, or re-direction onto the travel lanes. The manual review of crash reports provided critical supplementary information through narratives and diagrams not normally available through standard fields on police crash report forms. Statistical models were estimated to identify factors that affect the frequency, severity, and outcomes of median-related crashes, with particular emphases on differences between segments with varying median barrier types. Several roadway-, traffic-, and environmental-related characteristics were found to affect these metrics, with results varying across the different barrier types. The results of this study provide transportation agencies with important guidance as to the in-service performance of various types of median barrier. Copyright © 2018 Elsevier Ltd. All rights reserved.

Highly stretchable miniature strain sensor for large dynamic strain measurement

DOE PAGES

Song, Bo; Yao, Shurong; Nie, Xu; ...

2016-01-01

In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages,more » as its gauge factor is 500 times of that of the conventional foil strain gages.« less

Associations of a social network typology with physical and mental health risks among older adults in South Korea.

PubMed

Park, N S; Jang, Y; Lee, B S; Chiriboga, D A; Chang, S; Kim, S Y

2018-05-01

The objectives of this study were to (1) develop an empirical typology of social networks in older Koreans; and (2) examine its effect on physical and mental health. A sample of 6900 community-dwelling older adults in South Korea was drawn from the 2014 Korean National Elderly Survey. Latent profile analysis (LPA) was conducted to derive social network types using eight common social network characteristics (marital status, living arrangement, the number and frequency of contact with close family/relatives, the number and frequency of contact with close friends, frequency of participation in social activities, and frequency of having visitors at home). The identified typologies were then regressed on self-rated health and depressive symptoms to explore the health risks posed by the group membership. The LPA identified a model with five types of social network as being most optimal (BIC = 153,848.34, entropy = .90). The groups were named diverse/family (enriched networks with more engagement with family), diverse/friend (enriched networks with more engagement with friends), friend-focused (high engagement with friends), distant (structurally disengaged), and restricted (structurally engaged but disengaged in family/friends networks). A series of regression analyses showed that membership in the restricted type was associated with more health and mental health risks than all types of social networks except the distant type. Findings demonstrate the importance of family and friends as a source of social network and call attention to not only structural but also non-structural aspects of social isolation. Findings and implications are discussed in cultural contexts.

Expansion of the Knockdown Resistance Frequency Map for Human Head Lice (Phthiraptera: Pediculidae) in the United States Using Quantitative Sequencing

PubMed Central

Gellatly, Kyle J.; Krim, Sarah; Palenchar, Daniel J.; Shepherd, Katie; Yoon, Kyong Sup; Rhodes, Christopher J.; Lee, Si Hyeock; Marshall Clark, J.

2016-01-01

Pediculosis is a prevalent parasitic infestation of humans, which is increasing due, in part, to the selection of lice resistant to either the pyrethrins or pyrethroid insecticides by the knockdown resistance (kdr) mechanism. To determine the extent and magnitude of the kdr-type mutations responsible for this resistance, lice were collected from 138 collection sites in 48 U.S. states from 22 July 2013 to 11 May 2015 and analyzed by quantitative sequencing. Previously published data were used for comparisons of the changes in the frequency of the kdr-type mutations over time. Mean percent resistance allele frequency (mean % RAF) values across the three mutation loci were determined from each collection site. The overall mean % RAF (±SD) for all analyzed lice was 98.3 ± 10%. 132/138 sites (95.6%) had a mean % RAF of 100%, five sites (3.7%) had intermediate values, and only a single site had no mutations (0.0%). Forty-two states (88%) had a mean % RAF of 100%. The frequencies of kdr-type mutations did not differ regardless of the human population size that the lice were collected from, indicating a uniformly high level of resistant alleles. The loss of efficacy of the Nix formulation (Prestige Brand, Tarrytown, NY) from 1998 to 2013 was correlated to the increase in kdr-type mutations. These data provide a plausible reason for the decrease in the effectiveness of permethrin in the Nix formulation, which is the parallel increase of kdr-type mutations in lice over time. PMID:27032417

The low density type III ELMy H-mode regime on JET-ILW: a low density H-mode compatible with a tungsten divertor?

NASA Astrophysics Data System (ADS)

Delabie, E.; Hillesheim, J. C.; Mailloux, J.; Maggi, C. F.; Rimini, F.; Solano, E. R.; JET contributors Team

2016-10-01

The threshold power to access H-mode on JET-ILW has a minimum as function of density. Power ramps in the low and high density branch show qualitatively very different behavior above threshold. In the high density branch, edge density and temperature abruptly increase after the L-H transition, and the plasma evolves into a type I ELMy H-mode. Transitions in the low density branch are gradual and lead to the formation of a temperature pedestal, without increase in edge density. These characteristics are reminiscent of the I-mode regime, but with high frequency ELM activity. The small ELMs allow stable H-mode operation with tolerable tungsten contamination, as long as both density and power stay below the type I ELM boundary. The density range in which the low density branch can be accessed scales favourably with toroidal field but unfavourably with isotope mass. At BT=3.4T, a stable H-mode has been obtained at = 2.9 1019 m-3 with up to 15 MW of heating power at H98y 0.9. Better knowledge of the operational boundaries of this high frequency ELM regime could provide insight in how to sustain it at higher heating power for high temperature scenarios. Work supported, in part, by the US DOE under Contract No. DE-AC05-00OR22725.

The Importance of High-Risk Human Papillomavirus Types Other Than 16 and 18 in Cervical Neoplasia.

PubMed

Robadi, Ibrahim A; Pharaon, Majed; Ducatman, Barbara S

2018-06-01

- Types 16 and 18 are the most widely studied high-risk types of human papillomavirus (HPV). However, other high-risk HPV types (HPV non-16/18) also play a significant role in cervical neoplasia. Currently, screening and management algorithms separate out HPV 16/18 from all other HPV non-16/18 types. In addition, most of the previously vaccinated population has only been vaccinated for these high-risk types, so many women are still vulnerable to HPV non-16/18 infections. - To review the prevalence and role of HPV non-16/18 neoplasia and to review current surveillance, management, and vaccination strategies in view of these findings. - The study comprised a review of the literature. - Although HPV non-16/18 types are less frequently associated with cervical intraepithelial neoplasia and cancer, they are nonetheless a significant cause of disease. Further stratification of higher-risk HPV non-16/18 may be necessary to improve prevention and management, however, regional prevalence differences may make a unified approach difficult. As HPV 16/18 infections decrease owing to vaccination of at-risk women, the relative frequency of HPV non-16/18 will increase, although the latest vaccine covers several more high-risk types.

Association between human papilloma virus-type infections with micronuclei frequencies.

PubMed

Cortés-Gutiérrez, E I; Dávila-Rodríguez, M I; Vargas-Villarreal, J; Hernández-Garza, F; Cerda-Flores, R M

2010-01-01

To determine the association between Human papillomavirus (HPV)-type infections with the frequency of Micronucleus (MN), a hospital-based, unmatched case-control study was carried out. We evaluated and compared the average number of MN/1,000 cells among three groups of Mexican females. Twenty one women ranging in age from 31-56 years and divided into three groups were studied. Group I comprised seven control women without cervical lesions and with HPV-negative, Group II was composed of seven women with Squamous intraepithelial lesions (SIL) infected with low-risk HPV low-risk, and Group III was made up of seven women with SIL infected with high-risk HPV infection. Analysis of variance (ANOVA) test revealed differences among Groups I (5.14+/-3.02), II (13.43+/-3.41), and III (25.43+/-3.41) (F=67.46; P=0.0001). We demonstrated an association between HPV type infection and higher MN frequencies. However, a larger controlled study with sufficient follow-up will be required to further evaluate the usefulness of this test in the clinical management of women with HPV infection.

Auditory Temporal Resolution in Individuals with Diabetes Mellitus Type 2.

PubMed

Mishra, Rajkishor; Sanju, Himanshu Kumar; Kumar, Prawin

2016-10-01

Introduction  "Diabetes mellitus is a group of metabolic disorders characterized by elevated blood sugar and abnormalities in insulin secretion and action" (American Diabetes Association). Previous literature has reported connection between diabetes mellitus and hearing impairment. There is a dearth of literature on auditory temporal resolution ability in individuals with diabetes mellitus type 2. Objective  The main objective of the present study was to assess auditory temporal resolution ability through GDT (Gap Detection Threshold) in individuals with diabetes mellitus type 2 with high frequency hearing loss. Methods  Fifteen subjects with diabetes mellitus type 2 with high frequency hearing loss in the age range of 30 to 40 years participated in the study as the experimental group. Fifteen age-matched non-diabetic individuals with normal hearing served as the control group. We administered the Gap Detection Threshold (GDT) test to all participants to assess their temporal resolution ability. Result  We used the independent t -test to compare between groups. Results showed that the diabetic group (experimental) performed significantly poorer compared with the non-diabetic group (control). Conclusion  It is possible to conclude that widening of auditory filters and changes in the central auditory nervous system contributed to poorer performance for temporal resolution task (Gap Detection Threshold) in individuals with diabetes mellitus type 2. Findings of the present study revealed the deteriorating effect of diabetes mellitus type 2 at the central auditory processing level.

Epsilon-toxin plasmids of Clostridium perfringens type D are conjugative.

PubMed

Hughes, Meredith L; Poon, Rachael; Adams, Vicki; Sayeed, Sameera; Saputo, Juliann; Uzal, Francisco A; McClane, Bruce A; Rood, Julian I

2007-11-01

Isolates of Clostridium perfringens type D produce the potent epsilon-toxin (a CDC/U.S. Department of Agriculture overlap class B select agent) and are responsible for several economically significant enterotoxemias of domestic livestock. It is well established that the epsilon-toxin structural gene, etx, occurs on large plasmids. We show here that at least two of these plasmids are conjugative. The etx gene on these plasmids was insertionally inactivated using a chloramphenicol resistance cassette to phenotypically tag the plasmid. High-frequency conjugative transfer of the tagged plasmids into the C. perfringens type A strain JIR325 was demonstrated, and the resultant transconjugants were shown to act as donors in subsequent mating experiments. We also demonstrated the transfer of "unmarked" native epsilon-toxin plasmids into strain JIR325 by exploiting the high transfer frequency. The transconjugants isolated in these experiments expressed functional epsilon-toxin since their supernatants had cytopathic effects on MDCK cells and were toxic in mice. Using the widely accepted multiplex PCR approach for toxin genotyping, these type A-derived transconjugants were genotypically type D. These findings have significant implications for the C. perfringens typing system since it is based on the toxin profile of each strain. Our study demonstrated the fluid nature of the toxinotypes and their dependence upon the presence or absence of toxin plasmids, some of which have for the first time been shown to be conjugative.

Time-frequency analysis of phonocardiogram signals using wavelet transform: a comparative study.

PubMed

Ergen, Burhan; Tatar, Yetkin; Gulcur, Halil Ozcan

2012-01-01

Analysis of phonocardiogram (PCG) signals provides a non-invasive means to determine the abnormalities caused by cardiovascular system pathology. In general, time-frequency representation (TFR) methods are used to study the PCG signal because it is one of the non-stationary bio-signals. The continuous wavelet transform (CWT) is especially suitable for the analysis of non-stationary signals and to obtain the TFR, due to its high resolution, both in time and in frequency and has recently become a favourite tool. It decomposes a signal in terms of elementary contributions called wavelets, which are shifted and dilated copies of a fixed mother wavelet function, and yields a joint TFR. Although the basic characteristics of the wavelets are similar, each type of the wavelets produces a different TFR. In this study, eight real types of the most known wavelets are examined on typical PCG signals indicating heart abnormalities in order to determine the best wavelet to obtain a reliable TFR. For this purpose, the wavelet energy and frequency spectrum estimations based on the CWT and the spectra of the chosen wavelets were compared with the energy distribution and the autoregressive frequency spectra in order to determine the most suitable wavelet. The results show that Morlet wavelet is the most reliable wavelet for the time-frequency analysis of PCG signals.

[Superficial mycoses: comparative study between type 2 diabetic patients and a non-diabetic control group].

PubMed

García-Humbría, Leila; Richard-Yegres, Nicole; Pérez-Blanco, Maigualida; Yegres, Francisco; Mendoza, Mireya; Acosta, Arnaldo; Hernández, Rosaura; Zárraga, Eluz

2005-03-01

Superficial mycoses are considered to affect more frequently patients with type 2 diabetes mellitus (DM-2), specially onychomycosis and Tinea pedis. The purpose of this study was to compare the dermatophytoses, candidiasis and Pitiriasis versicolor frequency between 40 patients with DM-2 and 40 healthy persons of either sex, 40 years old or more. Clinical, metabolic, mycologic and inmunologic studies against Candida albicans, were carried out. Both diabetics 75% (30/40) and controls 65% (26/40) presented a high frequency of superficial mycoses (no significant difference p = 0.329). Pitiriasis versicolor was not detected in diabetic patients. They presented Tinea unguium, concomitant with Tinea pedis, with a higher frequency. The predominant dermatophyte was Trichophyton rubrum 18/23 (78%) in diabetics and 8/16 (50%) in non diabetics. Candida was isolated as commensal from oral mucous: 23/40 (58%) in diabetics and 21/40 (52%) in non diabetics (serotipo A was the more frequent), and from onychomycosis: 11/40 (28%) in diabetics and 12/40 (30%) in non diabetics. The immunological response was the same in both groups: celular 100%, humoral 20%. No statistical correlation among superficial mycoses, blood glucose level, glycosylated hemoglobin values or the time suffering the disease was observed. The high susceptibility to dermatophytes and Candida sp. infection showed to be associated with age and no with the diabetic type 2 condition in those patients.

The formation mechanism and evolution of ps-laser-induced high-spatial-frequency periodic surface structures on titanium

NASA Astrophysics Data System (ADS)

Pan, A. F.; Wang, W. J.; Mei, X. S.; Yang, H. Z.; Sun, X. F.

2017-01-01

We report the formation and evolution mechanisms of HSFLs (high-spatial-frequency laser-induced periodic surface structures) on the commercial pure titanium under 10-ps 532-nm-wavelength laser irradiation. At a lower peak laser fluence, HSFLs in the rough zone are first formed along the surface texture. Subsequently, HSFLs in the flat zone are formed with an orientation parallel to the laser polarization direction. The formation of HSFLs can be attributed to the parallel orientation of the initial periodic modulation of the electron plasma concentration to the laser polarization direction. In particular, the formation of HSFLs along the surface texture occurs because the absorbed laser energy density is along the surface texture. At a higher peak laser fluence, two types of HSFLs appear together with LSFLs. The first type involves HSFLs that initially cover the concave part of the LSFL (low-spatial-frequency laser-induced periodic surface structures) and penetrate inward as the number of spot overlaps increases. This formation mechanism can be attributed to cavitation instability. The second type involves HSFLs that are initially in the convex part of the LSFL, and they are transformed into oxidized nanodots as the number of spot overlaps increases. The oxidized nanodots increase the absorption of laser energy in titanium, which leads to the ablation and removal of the oxidized material. Therefore, the surface of the LSFL becomes smooth.

[Reparative Osteogenesis and Angiogenesis in Low Intensity Electromagnetic Radiation of Ultra-High Frequency].

PubMed

Iryanov, Y M; Kiryanov, N A

2015-01-01

Non-drug correction of reparative bone tissue regeneration in different pathological states - one of the most actual problems of modern medicine. Our aim was to conduct morphological analysis of the influence of electromagnetic radiation of ultra-high frequency and low intensity on reparative osteogenesis and angiogenesis in fracture treatment under transosseous osteosynthesis. A controlled nonrandomized study was carried out. In the experiment conducted on rats we modeled tibial fracture with reposition and fixation of the bone fragments both in control and experimental groups. In the animals of the experimental group the fracture zone was exposed to low intensity electromagnetic radiation of ultra-high frequency. Exposure simulation was performed in the control group. The operated bones were examined using radiography, light and electronic microscopy, X-ray electronic probe microanalysis. It has been established that electromagnetic radiation of ultra-high frequency sessions in fracture treatment stimulate secretory activity and degranulation of mast cells, produce microcirculatory bed vascular permeability increase, endotheliocyte migration phenotype expression, provide endovascular endothelial outgrowth formation, activate reparative osteogenesis and angiogenesis while fracture reparation becomes the one of the primary type. The full periosteal, intermediary and intraosteal bone union was defined in 28 days. Among the therapeutic benefits of electromagnetic radiation of ultra-high frequency in fracture treatment we can detect mast cell secretorv activity stimulation and endovascular anziozenesis activation.

Frequency-Wavenumber (FK)-Based Data Selection in High-Frequency Passive Surface Wave Survey

NASA Astrophysics Data System (ADS)

Cheng, Feng; Xia, Jianghai; Xu, Zongbo; Hu, Yue; Mi, Binbin

2018-04-01

Passive surface wave methods have gained much attention from geophysical and civil engineering communities because of the limited application of traditional seismic surveys in highly populated urban areas. Considering that they can provide high-frequency phase velocity information up to several tens of Hz, the active surface wave survey would be omitted and the amount of field work could be dramatically reduced. However, the measured dispersion energy image in the passive surface wave survey would usually be polluted by a type of "crossed" artifacts at high frequencies. It is common in the bidirectional noise distribution case with a linear receiver array deployed along roads or railways. We review several frequently used passive surface wave methods and derive the underlying physics for the existence of the "crossed" artifacts. We prove that the "crossed" artifacts would cross the true surface wave energy at fixed points in the f-v domain and propose a FK-based data selection technique to attenuate the artifacts in order to retrieve the high-frequency information. Numerical tests further demonstrate the existence of the "crossed" artifacts and indicate that the well-known wave field separation method, FK filter, does not work for the selection of directional noise data. Real-world applications manifest the feasibility of the proposed FK-based technique to improve passive surface wave methods by a priori data selection. Finally, we discuss the applicability of our approach.

Frequency-Wavenumber (FK)-Based Data Selection in High-Frequency Passive Surface Wave Survey

NASA Astrophysics Data System (ADS)

Cheng, Feng; Xia, Jianghai; Xu, Zongbo; Hu, Yue; Mi, Binbin

2018-07-01

Passive surface wave methods have gained much attention from geophysical and civil engineering communities because of the limited application of traditional seismic surveys in highly populated urban areas. Considering that they can provide high-frequency phase velocity information up to several tens of Hz, the active surface wave survey would be omitted and the amount of field work could be dramatically reduced. However, the measured dispersion energy image in the passive surface wave survey would usually be polluted by a type of "crossed" artifacts at high frequencies. It is common in the bidirectional noise distribution case with a linear receiver array deployed along roads or railways. We review several frequently used passive surface wave methods and derive the underlying physics for the existence of the "crossed" artifacts. We prove that the "crossed" artifacts would cross the true surface wave energy at fixed points in the f- v domain and propose a FK-based data selection technique to attenuate the artifacts in order to retrieve the high-frequency information. Numerical tests further demonstrate the existence of the "crossed" artifacts and indicate that the well-known wave field separation method, FK filter, does not work for the selection of directional noise data. Real-world applications manifest the feasibility of the proposed FK-based technique to improve passive surface wave methods by a priori data selection. Finally, we discuss the applicability of our approach.

Determining the frequency, depth and velocity of preferential flow by high frequency soil moisture monitoring

NASA Astrophysics Data System (ADS)

Hardie, Marcus; Lisson, Shaun; Doyle, Richard; Cotching, William

2013-01-01

Preferential flow in agricultural soils has been demonstrated to result in agrochemical mobilisation to shallow ground water. Land managers and environmental regulators need simple cost effective techniques for identifying soil - land use combinations in which preferential flow occurs. Existing techniques for identifying preferential flow have a range of limitations including; often being destructive, non in situ, small sampling volumes, or are subject to artificial boundary conditions. This study demonstrated that high frequency soil moisture monitoring using a multi-sensory capacitance probe mounted within a vertically rammed access tube, was able to determine the occurrence, depth, and wetting front velocity of preferential flow events following rainfall. Occurrence of preferential flow was not related to either rainfall intensity or rainfall amount, rather preferential flow occurred when antecedent soil moisture content was below 226 mm soil moisture storage (0-70 cm). Results indicate that high temporal frequency soil moisture monitoring may be used to identify soil type - land use combinations in which the presence of preferential flow increases the risk of shallow groundwater contamination by rapid transport of agrochemicals through the soil profile. However use of high frequency based soil moisture monitoring to determine agrochemical mobilisation risk may be limited by, inability to determine the volume of preferential flow, difficulty observing macropore flow at high antecedent soil moisture content, and creation of artificial voids during installation of access tubes in stony soils.

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

Song, Bo; Yao, Shurong; Nie, Xu

In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages,more » as its gauge factor is 500 times of that of the conventional foil strain gages.« less

Selective THz control of magnetic order: new opportunities from superradiant undulator sources

NASA Astrophysics Data System (ADS)

Kovalev, S.; Wang, Zhe; Deinert, J.-C.; Awari, N.; Chen, M.; Green, B.; Germanskiy, S.; de Oliveira, T. V. A. G.; Lee, J. S.; Deac, A.; Turchinovich, D.; Stojanovic, N.; Eisebitt, S.; Radu, I.; Bonetti, S.; Kampfrath, T.; Gensch, M.

2018-03-01

Recent advancements of accelerator technology enable the generation of carrier-envelope-phase stable THz pulses with high fields at adjustable high repetition rates. The appropriate choice of THz radiator allows generation of narrow-band, spectrally dense, multicycle THz transients of tunable THz frequency which are ideally suited to selectively excite low-energy excitations such as magnons or phonons. They also allow one to study the frequency dependence of nonresonant THz-field interactions with various order parameters with high dynamic range. In this paper, we discuss the future prospects of this new type of THz light source for studying the coherent control of magnetic order based on recent results.

FREQUENCY DEPENDENCE OF POLARIZATION OF ZEBRA PATTERN IN TYPE-IV SOLAR RADIO BURSTS

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

Kaneda, Kazutaka; Misawa, H.; Tsuchiya, F.

2015-08-01

We investigated the polarization characteristics of a zebra pattern (ZP) in a type-IV solar radio burst observed with AMATERAS on 2011 June 21 for the purpose of evaluating the generation processes of ZPs. Analyzing highly resolved spectral and polarization data revealed the frequency dependence of the degree of circular polarization and the delay between two polarized components for the first time. The degree of circular polarization was 50%–70% right-handed and it varied little as a function of frequency. Cross-correlation analysis determined that the left-handed circularly polarized component was delayed by 50–70 ms relative to the right-handed component over the entiremore » frequency range of the ZP and this delay increased with the frequency. We examined the obtained polarization characteristics by using pre-existing ZP models and concluded that the ZP was generated by the double-plasma-resonance process. Our results suggest that the ZP emission was originally generated in a completely polarized state in the O-mode and was partly converted into the X-mode near the source. Subsequently, the difference between the group velocities of the O-mode and X-mode caused the temporal delay.« less

Measured Attenuation of Coplanar Waveguide on 6H, p-type SiC and High Purity Semi-Insulating 4H SiC through 800 K

NASA Technical Reports Server (NTRS)

Ponchak, George E.; Schwartz, Zachary D.; Alterovitz, Samuel A.; Downey, Alan N.

2004-01-01

Wireless sensors for high temperature applications such as oil drilling and mining, automobiles, and jet engine performance monitoring require circuits built on wide bandgap semiconductors. In this paper, the characteristics of microwave transmission lines on 4H-High Purity Semi-Insulating SiC and 6H, p-type SiC is presented as a function of temperature and frequency. It is shown that the attenuation of 6H, p-type substrates is too high for microwave circuits, large leakage current will flow through the substrate, and that unusual attenuation characteristics are due to trapping in the SiC. The 4H-HPSI SiC is shown to have low attenuation and leakage currents over the entire temperature range.

Investigation of Tinnitus Patients in Italy: Clinical and Audiological Characteristics

PubMed Central

Martines, Francesco; Bentivegna, Daniela; Di Piazza, Fabiola; Martines, Enrico; Sciacca, Vincenzo; Martinciglio, Gioacchino

2010-01-01

Objective. 312 tinnitus sufferers were studied in order to analyze: the clinical characteristics of tinnitus; the presence of tinnitus-age correlation and tinnitus-hearing loss correlation; the impact of tinnitus on subjects' life and where possible the etiological/predisposing factors of tinnitus. Results. There is a slight predominance of males. The highest percentage of tinnitus results in the decades 61–70. Of the tinnitus sufferers, 197 (63.14%) have a hearing deficit (light hearing loss in 37.18% of cases). The hearing impairment results of sensorineural type in 74.62% and limited to the high frequencies in 58.50%. The tinnitus is referred as unilateral in 59.93%, a pure tone in 66.99% and 10 dB above the hearing threshold in 37.7%. It is limited to high frequencies in 72.10% of the patients with sensorineural hearing loss (SNHL) while the 88.37% of the patients with high-frequency SNHL have a high-pitched tinnitus (χ 2 = 66.26;P < .005). Conclusion. Hearing status and age represent the principal tinnitus related factors; there is a statistically significant association between high-pitched tinnitus and high-frequency SNHL. There is no significant correlation between tinnitus severity and tinnitus loudness confirming the possibility that neural connection involved in evoking tinnitus-related negative reactions are governed by conditioned reflexes. PMID:20652075

Association of Exposure to Radio-Frequency Electromagnetic Field Radiation (RF-EMFR) Generated by Mobile Phone Base Stations with Glycated Hemoglobin (HbA1c) and Risk of Type 2 Diabetes Mellitus.

PubMed

Meo, Sultan Ayoub; Alsubaie, Yazeed; Almubarak, Zaid; Almutawa, Hisham; AlQasem, Yazeed; Hasanato, Rana Muhammed

2015-11-13

Installation of mobile phone base stations in residential areas has initiated public debate about possible adverse effects on human health. This study aimed to determine the association of exposure to radio frequency electromagnetic field radiation (RF-EMFR) generated by mobile phone base stations with glycated hemoglobin (HbA1c) and occurrence of type 2 diabetes mellitus. For this study, two different elementary schools (school-1 and school-2) were selected. We recruited 159 students in total; 96 male students from school-1, with age range 12-16 years, and 63 male students with age range 12-17 years from school-2. Mobile phone base stations with towers existed about 200 m away from the school buildings. RF-EMFR was measured inside both schools. In school-1, RF-EMFR was 9.601 nW/cm² at frequency of 925 MHz, and students had been exposed to RF-EMFR for a duration of 6 h daily, five days in a week. In school-2, RF-EMFR was 1.909 nW/cm² at frequency of 925 MHz and students had been exposed for 6 h daily, five days in a week. 5-6 mL blood was collected from all the students and HbA1c was measured by using a Dimension Xpand Plus Integrated Chemistry System, Siemens. The mean HbA1c for the students who were exposed to high RF-EMFR was significantly higher (5.44 ± 0.22) than the mean HbA1c for the students who were exposed to low RF-EMFR (5.32 ± 0.34) (p = 0.007). Moreover, students who were exposed to high RF-EMFR generated by MPBS had a significantly higher risk of type 2 diabetes mellitus (p = 0.016) relative to their counterparts who were exposed to low RF-EMFR. It is concluded that exposure to high RF-EMFR generated by MPBS is associated with elevated levels of HbA1c and risk of type 2 diabetes mellitus.

Diabetes and Hearing Impairment in the United States: Audiometric Evidence from the National Health and Nutrition Examination Surveys, 1999–2004

PubMed Central

Bainbridge, Kathleen E.; Hoffman, Howard J.; Cowie, Catherine C.

2008-01-01

Background The vasculature and neural system of the inner ear may be affected by diabetes. Objective To determine whether hearing impairment is more prevalent among U.S. adults with diabetes than among those without diabetes. Design Cross-sectional analysis of nationally representative data. Setting National Health and Nutrition Examination Survey, 1999–2004. Participants 5140 non-institutionalized adults aged 20–69 years who underwent audiometric testing. Measurements Hearing impairment assessed from the pure tone average of thresholds over low/mid frequencies (500, 1000, 2000 Hz) and high frequencies (3000, 4000, 6000, 8000 Hz), and defined for mild or greater severity (pure tone average > 25 decibels hearing level (dB HL)) and moderate or greater severity (pure tone average > 40 dB HL). Results For low/mid frequency hearing impairment of mild or greater severity assessed in the worse ear, age-adjusted prevalence estimates (95% confidence limits) were 21.3% (15.0, 27.5) among 399 adults with diabetes and 9.4% (8.2, 10.5) among 4741 adults without diabetes. For high frequency hearing impairment of mild or greater severity assessed in the worse ear, age-adjusted prevalence estimates were 54.1% (45.9, 62.3) among those with diabetes and 32.0% (30.5, 33.5) among those without. Adjusted odds ratios (95% confidence limits) of 1.82 (1.27, 2.60) and 2.16 (1.47, 3.18) for the low/mid frequency and high frequency impairments, respectively, indicated that differences in socio-demographic characteristics, noise exposure, ototoxic medication use, and smoking did not account for the association between diabetes and hearing impairment. Limitations Diagnosed diabetes was based on self-report and does not distinguish between type 1 and type 2 diabetes. Noise exposure assessments were based on participant recall. Conclusion Adults with diabetes have a higher occurrence of hearing impairment than those without diabetes. Screening for this problem would allow for interventions to improve hearing. PMID:18559825

Word frequency and the attentional blink: the effects of target difficulty on retrieval and consolidation processes.

PubMed

Wierda, Stefan M; Taatgen, Niels A; van Rijn, Hedderik; Martens, Sander

2013-01-01

When a second target (T2) is presented in close succession of a first target (T1) within a stream of non-targets, people often fail to detect T2-a deficit known as the attentional blink (AB). Two types of theories can be distinguished that have tried to account for this phenomenon. Whereas attentional-control theories suggest that protection of consolidation processes induces the AB, limited-resource theories claim that the AB is caused by a lack of resources. According to the latter type of theories, increasing difficulty of one or both targets should increase the magnitude of the AB. Similarly, attentional-control theories predict that a difficult T1 increases the AB due to prolonged processing. However, the prediction for T2 is not as straightforward. Prolonged processing of T2 could cause conflicts and increase the AB. However, if consolidation of T2 is postponed without loss of identity, the AB might be attenuated. Participants performed an AB task that consisted of a stream of distractor non-words and two target words. Difficulty of T1 and T2 was manipulated by varying word-frequency. Overall performance for high-frequency words was better than for low-frequency words. When T1 was highly frequent, the AB was reduced. The opposite effect was found for T2. When T2 was highly frequent, performance during the AB period was relatively worse than for a low-frequency T2. A threaded-cognition model of the AB was presented that simulated the observed pattern of behavior by taking changes in the time-course of retrieval and consolidation processes into account. Our results were replicated in a subsequent ERP study. The finding that a difficult low-frequency T2 reduces the magnitude of the AB is at odds with limited-resource accounts of the AB. However, it was successfully accounted for by the threaded-cognition model, thus providing an explanation in terms of attentional control.

Method for manufacturing compound semiconductor field-effect transistors with improved DC and high frequency performance

DOEpatents

Zolper, John C.; Sherwin, Marc E.; Baca, Albert G.

2000-01-01

A method for making compound semiconductor devices including the use of a p-type dopant is disclosed wherein the dopant is co-implanted with an n-type donor species at the time the n-channel is formed and a single anneal at moderate temperature is then performed. Also disclosed are devices manufactured using the method. In the preferred embodiment n-MESFETs and other similar field effect transistor devices are manufactured using C ions co-implanted with Si atoms in GaAs to form an n-channel. C exhibits a unique characteristic in the context of the invention in that it exhibits a low activation efficiency (typically, 50% or less) as a p-type dopant, and consequently, it acts to sharpen the Si n-channel by compensating Si donors in the region of the Si-channel tail, but does not contribute substantially to the acceptor concentration in the buried p region. As a result, the invention provides for improved field effect semiconductor and related devices with enhancement of both DC and high-frequency performance.

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.

Molecular analyses of unrelated Charcot-Marie-Tooth (CMT) disease patients suggest a high frequency of the CMT1A duplication

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

Wise, C.A.; Davis, S.N.; Heju, Z.

1993-10-01

Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral neuropathy. One form of CMT, CMT type 1A, is characterized by uniformly decreased nerve conduction velocities, usually shows autosomal dominant inheritance, and is associated with a large submicroscopic duplication of the p11.2-p12 region of chromosome 17. A cohort of 75 unrelated patients diagnosed clinically with CMT and evaluated by electrophysiological methods were analyzed molecularly for the presence of the CMT1A DNA duplication. Three methodologies were used to assess the duplication: Measurement of dosage differences between RFLP alleles, analysis of polymorphic (GT)[sub n] repeats, and detection of a junction fragment by pulsed-fieldmore » gel electrophoresis. The CMT1A duplication was found in 68% of the 63 unrelated CMT patients with electrophysiological studies consistent with CMT type 1 (CMT1). The CMT1A duplication was detected as a de novo event in two CMT1 families. Twelve CMT patients who did not have decreased nerve conduction velocities consistent with a diagnosis of CMT type 2 (CMT2) were found not to have the CMT1A duplication. The most informative molecular method was the detection of the CMT1A duplication-specific junction fragment. Given the high frequency of the CMT1A duplication in CMT patients and the high frequency of new mutations, the authors conclude that a molecular test for the CMT1A DNA duplication is very useful in the differential diagnosis of patients with peripheral neuropathies. 61 refs., 4 figs.« less

Multi-Source Generation Mechanisms for Low Frequency Noise Induced by Flood Discharge and Energy Dissipation from a High Dam with a Ski-Jump Type Spillway

PubMed Central

Lian, Jijian; Zhang, Wenjiao; Ma, Bin; Liu, Dongming

2017-01-01

As excess water is discharged from a high dam, low frequency noise (air pulsation lower than 10 Hz, LFN) is generated and propagated in the surrounding areas, causing environmental hazards such as the vibration of windows and doors and the discomfort of local residents. To study the generation mechanisms and key influencing factors of LFN induced by flood discharge and energy dissipation from a high dam with a ski-jump type spillway, detailed prototype observations and analyses of LFN are carried out. The discharge flow field is simulated and analyzed using a gas-liquid turbulent flow model. The acoustic response characteristics of the air cavity, which is formed between the discharge nappe and dam body, are analyzed using an acoustic numerical model. The multi-sources generation mechanisms are first proposed basing on the prototype observation results, vortex sound model, turbulent flow model and acoustic numerical model. Two kinds of sources of LFN are studied. One comes from the energy dissipation of submerged jets in the plunge pool, the other comes from nappe-cavity coupled vibration. The results of the analyses reveal that the submerged jets in the plunge pool only contribute to an on-site LFN energy of 0–1.0 Hz, and the strong shear layers around the high-velocity submerged jets and wall jet development areas are the main acoustic source regions of LFN in the plunge pool. In addition, the nappe-cavity coupled vibration, which is induced when the discharge nappe vibrates with close frequency to the model frequency of the cavity, can induce on-site LFN energy with wider frequency spectrum energy within 0–4.0 Hz. By contrast, the contribution degrees to LFN energy from two acoustic sources are almost same, while the contribution degree from nappe-cavity coupled vibration is slightly higher. PMID:29189750

A study on the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise.

PubMed

Takahashi, Yukio

2011-01-01

To investigate the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise, we conducted two experiments. In Experiment 1, eight male subjects were exposed to seven types of low-frequency noise stimuli: two pure tones [a 31.5-Hz, 100-dB(SPL) tone and a 50-Hz, 100-dB(SPL) tone] and five complex noises composed of the pure tones. For the complex noise stimuli, the sound pressure level of one tonal component was 100 dB(SPL) and that of another one was either 90, 95, or 100 dB(SPL). Vibration induced on the body surface was measured at five locations, and the correlation with the subjective rating of the vibratory sensation at each site of measurement was examined. In Experiment 2, the correlation between the body surface vibration and the vibratory sensation was similarly examined using seven types of noise stimuli composed of a 25-Hz tone and a 50-Hz tone. In both the experiments, we found that at the chest and the abdomen, the rating of the vibratory sensation was in close correlation with the vibration acceleration level (VAL) of the body surface vibration measured at each corresponding location. This was consistent with our previous results and suggested that at the trunk of the body (the chest and the abdomen), the mechanoreception of body vibrations plays an important role in the experience of the vibratory sensation in persons exposed to high-level low-frequency noise. At the head, however, no close correlation was found between the rating of the vibratory sensation and the VAL of body surface vibration. This suggested that at the head, the perceptual mechanisms of vibration induced by high-level low-frequency noise were different from those in the trunk of the body.

[Development of new type plastics air turbine handpiece for dental use].

PubMed

Kusano, M

1989-06-01

The noise generated by the metal air turbine handpiece employed in dental practice is considerable and attended with predominant high frequency components. Therefore, investigation of the noise generation mechanism and development of a silent air turbine handpiece was only a matter of course. In addition, the metal air turbine hardpiece is comparatively heavy and its production cost is high. From this point of view as well, production of a light air turbine handpiece at low cost is also desirable. In order to overcome the objections to the metal air turbine handpiece, appropriate plastics materials were employed wherever possible. In this study, the number of revolutions, noise level, frequency analysis, start pressure and weight of newly produced plastics handpieces and metal handpieces were examined and compared. The following results were obtained: 1. The number of revolutions of single-nozzle type air turbine handpieces encased in plastics housings and fitted with metal turbine rotors was higher than that of all-metal air turbine handpieces. The noise level of the former tended to be lower. 2. The number of revolutions of multi-nozzle type air turbine handpieces encased in plastics housings and fitted with turbine rotors with plastics turbine blades was almost equal to that of similar metal handpieces, with the noise level tending to be lower. 3. In the case of handpieces fitted with turbine rotors with dynamic balance, the number of revolutions was high and the noise level was low. This indicated that dynamic balance was a factor affecting the number of revolutions and noise level. 4. Narrow band sound frequency analysis of single-nozzle type air turbine handpieces showed a sharp peak at the fundamental frequency which was the same as the number of revolutions multiplied by the number of rotor turbine blades. It is thought that the noise from air turbine handpieces was aerodynamic in origin, being generated by the periodical interruption of steady air flow by rotor turbine blades. 5. The start pressure of plastics handpieces was almost equal to that of metal handpieces. 6. The weight of plastics handpieces was 20%-50% of that of metal handpieces. The present results indicate that it is possible to produce a new type of light, silent and aesthetical air turbine handpiece.

Determination of sound types and source levels of airborne vocalizations by California sea lions, Zalophus californianus, in rehabilitation at the Marine Mammal Center in Sausalito, California

NASA Astrophysics Data System (ADS)

Schwalm, Afton Leigh

California sea lions (Zalophus californianus) are a highly popular and easily recognized marine mammal in zoos, aquariums, circuses, and often seen by ocean visitors. They are highly vocal and gregarious on land. Surprisingly, little research has been performed on the vocalization types, source levels, acoustic properties, and functions of airborne sounds used by California sea lions. This research on airborne vocalizations of California sea lions will advance the understanding of this aspect of California sea lions communication, as well as examine the relationship between health condition and acoustic behavior. Using a PhillipsRTM digital recorder with attached microphone and a calibrated RadioShackRTM sound pressure level meter, acoustical data were recorded opportunistically on California sea lions during rehabilitation at The Marine Mammal Center in Sausalito, CA. Vocalizations were analyzed using frequency, time, and amplitude variables with Raven Pro: Interactive Sound Analysis Software Version 1.4 (The Cornell Lab of Ornithology, Ithaca, NY). Five frequency, three time, and four amplitude variables were analyzed for each vocalization. Differences in frequency, time, and amplitude variables were not significant by sex. The older California sea lion group produced vocalizations that were significantly lower in four frequency variables, significantly longer in two time variables, significantly higher in calibrated maximum and minimum amplitude variables, and significantly lower in frequency at maximum and minimum amplitude compared with pups. Six call types were identified: bark, goat, growl/grumble, bark/grumble, bark/growl, and grumble/moan. The growl/grumble call was higher in dominant beginning, ending, and minimum frequency, as well as in the frequency at maximum amplitude compared with the bark, goat, bark/grumble calls in the first versus last vocalization sample. The goat call was significantly higher in first harmonic interval than any other call type in the all vocalizations sample. The "fate" of a sea lion was categorized as: released, placed at another facility, remained at TMMC, euthanized, or died. To determine if acoustic features could be used to assess the recovery of a pup, the acoustic features of a pup's first recorded vocalization were compared with the frequency, time, and amplitude of the last vocalization recorded (i.e., before it was released or placed at another facility). In addition, all first vocalizations were pooled and all last vocalizations were pooled for acoustic analysis, regardless of their fate. Released pups had shorter duration calls, a greater first harmonic interval, and a higher dominant maximum frequency than either pups that died or pups remaining at TMMC. Released pups had a higher frequency at maximum and minimum amplitude compared to dead and remaining pups. Pups that died had significantly lower dominant ending frequency and a lower dominant minimum frequency than released or remaining pups. These results were supported by other studies on different species of otariids, phocids, and cetaceans. The preliminary analyses presented in this thesis holds promise that with additional data acoustic features of California sea lion airborne vocalizations could indicate sex, age, and possibly health condition or the potential for release.

iHADAMAC: A complementary tool for sequential resonance assignment of globular and highly disordered proteins

NASA Astrophysics Data System (ADS)

Feuerstein, Sophie; Plevin, Michael J.; Willbold, Dieter; Brutscher, Bernhard

2012-01-01

An experiment, iHADAMAC, is presented that yields information on the amino-acid type of individual residues in a protein by editing the 1H- 15N correlations into seven different 2D spectra, each corresponding to a different class of amino-acid types. Amino-acid type discrimination is realized via a Hadamard encoding scheme based on four different spin manipulations as recently introduced in the context of the sequential HADAMAC experiment. Both sequential and intra-residue HADAMAC experiments yield highly complementary information that greatly facilitate resonance assignment of proteins with high frequency degeneracy, as demonstrated here for a 188-residue intrinsically disordered protein fragment of the hepatitis C virus protein NS5A.

Low and high dose rate heavy ion radiation-induced intestinal and colonic tumorigenesis in APC1638N/+ mice

NASA Astrophysics Data System (ADS)

Suman, Shubhankar; Kumar, Santosh; Moon, Bo-Hyun; Fornace, Albert J.; Datta, Kamal

2017-05-01

Ionizing radiation (IR) is a recognized risk factor for colorectal cancer (CRC) and astronauts undertaking long duration space missions are expected to receive IR doses in excess of permissible limits with implications for colorectal carcinogenesis. Exposure to IR in outer space occurs at low doses and dose rates, and energetic heavy ions due to their high linear energy transfer (high-LET) characteristics remain a major concern for CRC risk in astronauts. Previously, we have demonstrated that intestinal tumorigenesis in a mouse model (APC1638N/+) of human colorectal cancer was significantly higher after exposure to high dose rate energetic heavy ions relative to low-LET γ radiation. The purpose of the current study was to compare intestinal tumorigenesis in APC1638N/+ mice after exposure to energetic heavy ions at high (50 cGy/min) and relatively low (0.33 cGy/min) dose rate. Male and female mice (6-8 weeks old) were exposed to either 10 or 50 cGy of 28Si (energy: 300 MeV/n; LET: 70 keV/μm) or 56Fe (energy: 1000 MeV/n; LET: 148 keV/μm) ions at NASA Space Radiation Laboratory in Brookhaven National Laboratory. Mice (n = 20 mice/group) were euthanized and intestinal and colon tumor frequency and size were counted 150 days after radiation exposure. Intestinal tumorigenesis in male mice exposed to 56Fe was similar for high and low dose rate exposures. Although male mice showed a decreasing trend at low dose rate relative to high dose rate exposures, the differences in tumor frequency between the two types of exposures were not statistically significant after 28Si radiation. In female mice, intestinal tumor frequency was similar for both radiation type and dose rates tested. In both male and female mice intestinal tumor size was not different after high and low dose rate radiation exposures. Colon tumor frequency in male and female mice after high and low dose rate energetic heavy ions was also not significantly different. In conclusion, intestinal and colonic tumor frequency and size was similar irrespective of energetic heavy ion radiation dose rate suggesting that carcinogenic potential of energetic heavy ions is independent of dose rate.

Study on a Single-Stage 120 HZ Pulse Tube Cryocooler

NASA Astrophysics Data System (ADS)

Wu, Y. Z.; Gan, Z. H.; Qiu, L. M.; Chen, J.; Li, Z. P.

2010-04-01

Miniaturization of pulse tube cryocoolers is required for some particular applications where size and mass for devices are limited. In order to pack more cooling power in a small volume, higher operating frequencies are commonly used for Stirling-type pulse tube cryocoolers. To maintain high efficiency of the regenerator with a higher frequency, a higher charging pressure, smaller hydraulic diameters of regenerator material and a shorter regenerator length should be applied. A rapid growth of research and development on pulse tube cryocoolers operating at a high frequency over 100 Hz in the last 3 years has occurred. In this study, a single stage pulse tube cryocooler with 120 Hz to provide 10 W of lift at 80 K has been developed by using the numerical model, known as REGEN 3.2. Experiments performed on this cryocooler driven by a CFIC linear compressor show that a no-load temperature of 49.6 K was achieved and the net refrigeration power at 78.5 K was 8.0 W. The effect of pulse tube orientation was tested, and the copper velvet as a regenerator matrix was proposed for high frequency operation.

The influence of seizure frequency on anterograde and remote memory in mesial temporal lobe epilepsy.

PubMed

Voltzenlogel, Virginie; Vignal, Jean-Pierre; Hirsch, Edouard; Manning, Liliann

2014-10-01

Seizure frequency, although considered as an important factor in memory impairment in mesial temporal epilepsy (mTLE), is mostly confounded with other clinical variables, making it unclear to what extent recurrent seizures actually interfere with memory. The present study focuses on the influence of seizure frequency, studied as a main variable, on anterograde and remote memory. Seventy-one patients with unilateral mTLE were divided into two subgroups, as a function of their seizure frequency (monthly versus weekly seizures). Other seizure-related variables were controlled, namely, lateralisation and type of lesion, age at onset, years of ongoing seizures, etiologic factors, and number of AED. A comprehensive neuropsychological examination, including anterograde memory (verbal and non verbal recognition memory and free recall) tasks together with a large range of tests exploring different domains of remote memory, was carried out. Despite similar results on IQ, executive functions and attention, the low seizure-frequency group performed significantly better than the high seizure-frequency group on anterograde memory tests. Loss of autobiographical episodes and public-events memory, concomitant with spared personal semantic knowledge, was observed in both patient groups compared with healthy subjects. A worsening effect of high seizure frequency was recorded for autobiographical incidents and news-events memory, but unexpectedly, not for memory for famous people. The study of seizure frequency as the main variable leads us to suggest that high seizure frequency, itself, potentiates the effects of mesial temporal lobe damage on episodic memory deficits. Copyright © 2014 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Advanced Pumped Storage Hydropower and Ancillary Services Provision

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

Muljadi, Eduard; Gevorgian, Vahan; Mohanpurkar, Manish

This paper presents a high-level overview of the capability of advanced pumped storage hydropower to provide ancillary services including frequency regulation and oscillation damping. Type 3 and Type 4 generators are discussed. The examples given are for a small power system that uses a diesel generator as the main generator and a very large system that uses a gas turbine as the main generator.

Frequency and longitudinal trends of household care product use

NASA Astrophysics Data System (ADS)

Moran, Rebecca E.; Bennett, Deborah H.; Tancredi, Daniel J.; Wu, Xiangmei (May); Ritz, Beate; Hertz-Picciotto, Irva

2012-08-01

The use of household cleaning products and air fresheners exposes people to a variety of chemicals, including some that have been shown to be irritants, potential carcinogens and endocrine disrupting compounds. In addition, some react with ambient ozone infiltrating to the indoor environment to form potentially toxic secondary pollutants. Although realistic estimates of usage patterns are necessary for modeling potential exposures in risk assessments, few studies have documented cleaning habits and product usage to characterize how they vary between households and over time. In addition, understanding within-household temporal variability of use is important to assess the reliability of exposure questionnaires used in epidemiological surveys and improve the cost-efficiency of data collection. In the SUPERB (Study of Use of Products and Exposure-Related Behavior) study, frequencies of use of eight types of household cleaning products and air fresheners and the performance of different types of cleaning tasks are collected in three annual telephone and six quarterly web-based surveys. All-purpose and glass cleaners were the products most frequently used among all products surveyed. Use frequencies differed by demographic and other household characteristics for some products. Product usage was internally consistent, with over 75% of pairwise cross-sectional correlations between product types statistically significantly different from zero. In addition, each product type was correlated with at least one cleaning habit. Frequency of cleaning product use and performing cleaning tasks did not vary by season. An examination of intra-household variability showed moderately to highly consistent usage patterns over time, with lower temporal consistency observed among products used more frequently, such as all-purpose cleaners. Frequency of household care product usage was consistent enough that in epidemiologic studies, participants can be classified, for example, into three categories on the basis of a single assessment, with only minimal misclassification.

Chromospheric Evaporation and Decimetric Radio Emission in Solar Flares

NASA Technical Reports Server (NTRS)

Aschwanden, Markus J.; Benz, Arnold O.

1995-01-01

We have discovered decimetric signatures of the chromospheric evaporation process. Evidence for the radio detection of chromospheric evaporation is based on the radio-inferred values of (1) the electron density, (2) the propagation speed, and (3) the timing, which are found to be in good agreement with statistical values inferred from the blueshifted Ca xix soft X-ray line. The physical basis of our model is that free-free absorption of plasma emission is strongly modified by the steep density gradient and the large temperature increase in the upflowing flare plasma. The steplike density increase at the chromospheric evaporation front causes a local discontinuity in the plasma frequency, manifested as almost infinite drift rate in decimetric type III bursts. The large temperature increase of the upflowing plasma considerably reduces the local free-free opacity (due to the T-(exp -3/2) dependence) and thus enhances the brightness of radio bursts emitted at the local plasma frequency near the chromospheric evaporation front, while a high-frequency cutoff is expected in the high-density regions behind the front, which can be used to infer the velocity of the upflowing plasma. From model calculations we find strong evidence that decimetric bursts with a slowly drifting high-frequency cutoff are produced by fundamental plasma emission, contrary to the widespread belief that decimetric bursts are preferentially emitted at the harmonic plasma level. We analyzed 21 flare episodes from 1991-1993 for which broadband (100-3000 MHz) radio dynamic spectra from Phoenix, hard X-ray data from BATSE/CGRO, and soft X-ray data from GOES were available. We detected slowly drifting high-frequency cutoffs between 1.1 and 3.0 GHz, with drift rates of -41 +/- 32 MHz/s, extending over time intervals of 24 +/- 23 s. Developing a density model for type III-emitting flare loops based on the statistically observed drift rate of type III bursts by Alvarez & Haddock, we infer velocities of up to 360 km/s for the upflowing plasma, with an average of v(sub CE) = 236 +/- 130 km /s for episodes with 5-15 s duration. The mean electron density of the upflowing plasma is n(sub e) = 5.2(+/-3.1) x 10(exp 10) /cu cm when it is first detected in radio, at coronal altitudes of h(sub 0) = 9.2 +/- 2.3 Mm.

Contact flexible microstrip applicators (CFMA) in a range from microwaves up to short waves.

PubMed

Gelvich, Edward A; Mazokhin, Vladimir N

2002-09-01

Contact flexible microstrip applicator (CFMA) is a new light-weight microstrip applicator type for superficial and deep local hyperthermia. Typical specimens are developed for operation at frequencies of 434, 70, 40, and 27 MHz. The main common features of CFMA, namely, their flexibility and light weight, as well as their aperture dimensions slightly depend on the operating frequency. Two antenna types are used in CFMAs: inductive antennas with a radiating plane electrical dipole at microwaves, and coplanar capacitive antennas, providing depression of the normal component of the electrical field in the very high-frequency (VHF) and high-frequency (HF) range. The flexibility of the applicators enables one to conform them with curved surfaces. In a bent state of the applicators there arises a focusing effect of energy deposition in deeper located tissues due to linear polarization of the irradiated electromagnetic (EM) field, inherent in CFMA. All CFMA are integrated with silicon water boluses which serve as a matching element, so as a skin cooling agent. Due to this and to the predominance of the tangential electrical component in the radiated EM field, no fat overheating effects are noticed, as a rule. The aperture of the developed applicators overlap the range 160-630 cm2 providing effective heating field sizes (EFSs) 64-400 cm2, respectively. The most bulky CFMAs with an aperture of (21 x 29) cm2 operating at the frequency of 434 MHz weigh 0.8 kg and 2.5 kg at 27 MHz. Phenomenological analysis of the radiating systems, as well as experimental evaluation of the applicators are presented. CFMAs operating at frequencies of 434 and 40 MHz are used in clinical practice. CFMA at 70 and 27 MHz are subjected to laboratory clinical investigations.

Excitation of high frequency pressure driven modes in non-axisymmetric equilibrium at high βpol in PBX-M

NASA Astrophysics Data System (ADS)

Sesnic, S.; Holland, A.; Kaita, R.; Kaye, S. M.; Okabayashi, M.; Takahashi, H.; Asakura, N.; Bell, R. E.; Bernabei, S.; Chance, M. S.; Duperrex, P.-A.; Fonck, R. J.; Gammel, G. M.; Greene, G. J.; Hatcher, R. E.; Jardin, S. C.; Jiang, T.; Kessel, C. E.; Kugel, H. W.; Leblanc, B.; Levinton, F. M.; Manickam, J.; Ono, M.; Paul, S. F.; Powell, E. T.; Qin, Y.; Roberts, D. W.; Sauthoff, N. R.

1993-12-01

High frequency pressure driven modes have been observed in high poloidal beta discharges in the Princeton Beta Experiment Modification (PBX-M). These modes are excited in a non-axisymmetric equilibrium characterized by a large, low frequency mt = 1/nt = 1 island, and they are capable of expelling fast ions. The modes reside on or very close to the q = 1 surface and have mode numbers with either mh = nh or (less probably) mh/nh = mh/(mh-1), with mh varying between 3 and 10. Occasionally these modes are simultaneously localized in the vicinity of the ml = 2/nl = 1 island. The high frequency modes near the q = 1 surface also exhibit a ballooning character, being significantly stronger on the large major radius side of the plasma. When a large mt = 1/nt = 1 island is present, the mode is poloidally localized in the immediate vicinity of the X point of the island. The modes occur exclusively in high beta beam heated discharges and are likely to be driven by the beam ions. They can thus be a manifestation of either a toroidicity induced shear Alfven eigenmode (TAE) at q = (2mh+1)/2nh, a kinetic ballooning mode, or some other type of pressure driven (high β) mode. Most of the data are consistent with the theoretical predictions for the TAE gap mode. Since the high frequency modes in PBX-M, however, are found exclusively on or in the immediate neighbourhood of magnetic surfaces with low rational numbers (q = 1, 2,...), other possibilities are not excluded

Impedance Spectroscopy Analysis of Mg4Nb2O9 Ceramics with Different Additions of V2O5 for Microwave and Radio Frequency Applications

NASA Astrophysics Data System (ADS)

Filho, J. M. S.; Rodrigues Junior, C. A.; Sousa, D. G.; Oliveira, R. G. M.; Costa, M. M.; Barroso, G. C.; Sombra, A. S. B.

2017-07-01

The complex impedance spectroscopy study of magnesium niobate Mg4Nb2O9 (MN) ceramics with different additions of V2O5 (0%, 2%, 5%) was performed in this present paper. The preparation of MN samples were carried out by using the solid-state reaction method with a high-energy milling machine. Frequency and temperature dependence of the complex impedance, complex modulus analysis, and conductivity were measured and calculated at different temperatures by using a network impedance analyzer. A non-Debye type relaxation was observed showing a decentralization of the semicircles. Cole-Cole formalism was adopted here with the help of a computer program used to fit the experimental data. A typical universal dielectric response in the frequency-dependent conductivity at different temperatures was found. The frequency dependent ac conductivity at different temperatures indicates that the conduction process is thermally activated. The activation energy was obtained from the Arrhenius fitting by using conductivity and electrical modules data. The results would help to understand deeply the relaxation process in these types of materials.

Low-loss Z-type barium hexaferrite composites from nanoscale ZnAl2O4 addition for high-frequency applications

NASA Astrophysics Data System (ADS)

Zheng, Zongliang; Feng, Quanyuan; Harris, Vincent G.

2018-05-01

In this study, nanocrystalline ZnAl2O4 (ZA) were introduced to Z-type barium hexaferrite (Co2Z) and the effects of ZA addition upon the crystal-phase composition, microstructure, permeability and permittivity as well as losses characteristics over a wide frequency range of 10 MHz-1 GHz have been systematically investigated. With increasing ZA content (x) from 0 to 15 wt%, the permeability μ' at low frequencies decreased from 12.0 to 4.3, while the permittivity ɛ' was decreased from 27.4 to 10.7. Correspondingly, the frequency stability of permeability and permittivity were improved and the losses were effectively reduced. When x is in the range of 5-10 wt%, the magnetic loss tan δμ is in the order of 10-2 and the dielectric loss tan δɛ is in the order of 10-3 at 300 MHz, which is lower by one order of magnitude compared with that of undoped Co2Z. The modified magnetic and dielectric properties are closely related to the changing phase composition and microstructure.

High-frequency ultrasound imaging for cutaneous neurofibroma in patients with neurofibromatosis type I.

PubMed

Raffin, Delphine; Zaragoza, Julia; Georgescou, Gabriella; Mourtada, Youssef; Maruani, Annabel; Ossant, Frédéric; Patat, Frédéric; Vaillant, Loïc; Machet, Laurent

2017-06-01

Neurofibromas (NFs) are benign tumours arising from a nerve sheath, which are present in nearly all patients with neurofibromatosis type 1 (NF1). High-frequency ultrasound (HFU) systems, using frequencies over 20 MHz, were developed to improve visualization of skin tumours by means of increased resolution. To describe NFs by using HFU in patients with NF1. Anonymized HFU (25-MHz) images of NFs were randomized. Initially, two dermatologist investigators, with experience in HFU imaging of the skin, together described the ultrasound images and established eight criteria for NFs. The same task was then repeated by two other dermatologists, also with experience in HFU imaging of the skin, independently, to establish inter-observer agreement. A total of 108 NFs in 29 patients were included. Superficial and subcutaneous NFs were hypoechoic with a round to spindle shape. Plexiform NFs were ill-defined, consisting of multiple hypoechoic linear zones. Good to excellent inter-observer agreement was found for six of the eight criteria (k>0.6). This is the first series describing HFU skin imaging of NFs in patients with NF1. Lateral extension that may correspond to involvement of an adjacent nerve seems to be specific to NFs.

Impedance of (CoFeZr)0,559(PbZrTiO3)0,441 nanocomposite annealed in a tubular furnace

NASA Astrophysics Data System (ADS)

Boiko, Oleksandr

2016-12-01

The objective of the present research has been to determine the influence of annealing in tubular furnace on capacity of (CoFeZr)0,559(PbZrTiO3)0,441 nanocomposite produced by ion beam sputtering using combined argon and oxygen beam. The phase angle of the nanocomposite directly after preparing demonstrates negative values, which indicates the capacitive type of electrical conductivity of the material. The rapid increase of conductivity when frequency increases indicates hopping conductance in the material. The additional polarization of the nanocomposite occurs with its extinction in the area of high frequencies. The electrons relaxation time has been defined as of ca τ = 1,25×10-4 s. Annealing of nanocomposite sample x = 55.9 at.% at temperature Ta = 548 K causes phase angle obtains positive values in high frequency area, which indicates the change of conduction type from capacitive to inductive. The voltage resonance phenomenon occurs in the material. Annealing in temperature of Ta = 648 K causes changes of the nanomaterials capacity. The additional oxidization of CoFeZr metallic phase nanograins which provides to the potential barrier formation around potential wells (CoFeZr nanoparticles).

Laser ion source for heavy ion inertial fusion

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

Okamura, Masahiro

The proposed heavy ion inertial fusion (HIF) scenarios require ampere class low charge state ion beams of heavy species. A laser ion source (LIS) is recognized as one of the promising candidates of ion beam providers, since it can deliver high brightness heavy ion beams to accelerators. A design of LIS for the HIF depends on the accelerator structure and accelerator complex following the source. In this article, we discuss the specifications and design of an appropriate LIS assuming two major types of the accelerators: radio frequency (RF) high quality factor cavity type and non-resonant induction core type. We believemore » that a properly designed LIS satisfies the requirements of both types, however some issues need to be verified experimentally.« less

Laser ion source for heavy ion inertial fusion

DOE PAGES

Okamura, Masahiro

2018-01-10

The proposed heavy ion inertial fusion (HIF) scenarios require ampere class low charge state ion beams of heavy species. A laser ion source (LIS) is recognized as one of the promising candidates of ion beam providers, since it can deliver high brightness heavy ion beams to accelerators. A design of LIS for the HIF depends on the accelerator structure and accelerator complex following the source. In this article, we discuss the specifications and design of an appropriate LIS assuming two major types of the accelerators: radio frequency (RF) high quality factor cavity type and non-resonant induction core type. We believemore » that a properly designed LIS satisfies the requirements of both types, however some issues need to be verified experimentally.« less

High frequency/ultrasonic communication in a critically endangered nocturnal primate, Claire's mouse lemur (Microcebus mamiratra).

PubMed

Hasiniaina, Alida F; Scheumann, Marina; Rina Evasoa, Mamy; Braud, Diane; Rasoloharijaona, Solofonirina; Randrianambinina, Blanchard; Zimmermann, Elke

2018-05-02

The critically endangered Claire's mouse lemur, only found in the evergreen rain forest of the National Park Lokobe (LNP) and a few lowland evergreen rain forest fragments of northern Madagascar, was described recently. The present study provides the first quantified information on vocal acoustics of calls, sound associated behavioral context, acoustic niche, and vocal activity of this species. We recorded vocal and social behavior of six male-female and six male-male dyads in a standardized social-encounter paradigm in June and July 2016 at the LNP, Nosy Bé island. Over six successive nights per dyad, we audio recorded and observed behaviors for 3 hr at the beginning of the activity period. Based on the visual inspection of spectrograms and standardized multiparametric sound analysis, we identified seven different call types. Call types can be discriminated based on a combination of harmonicity, fundamental frequency variation, call duration, and degree of tonality. Acoustic features of tonal call types showed that for communication, mouse lemurs use the cryptic, high frequency/ultrasonic frequency niche. Two call types, the Tsak and the Grunt call, were emitted most frequently. Significant differences in vocal activity of the Tsak call were found between male-female and male-male dyads, linked primarily to agonistic conflicts. Dominant mouse lemurs vocalized more than subdominant ones, suggesting that signaling may present an honest indicator of fitness. A comparison of our findings of the Claire's mouse lemur with published findings of five bioacoustically studied mouse lemur species points to the notion that a complex interplay between ecology, predation pressure, and phylogenetic relatedness may shape the evolution of acoustic divergence between species in this smallest-bodied primate radiation. Thus, comparative bioacoustic studies, using standardized procedures, are promising to unravel the role of vocalization for primate species diversity and evolution and for identifying candidates for vocalization-based non-invasive monitoring for conservation purposes. © 2018 Wiley Periodicals, Inc.

Spatio-temporal atmospheric circulation variability around the Antarctic Peninsula based on hemispheric circulation modes and weather types

NASA Astrophysics Data System (ADS)

Wachter, Paul; Beck, Christoph; Philipp, Andreas; Jacobeit, Jucundus; Höppner, Kathrin

2017-04-01

Large parts of the Polar Regions are affected by a warming trend associated with substantial changes in the cryosphere. In Antarctica this positive trend pattern is most dominant in the western part of the continent and on the Antarctic Peninsula (AP). An important driving mechanism of temperature variability and trends in this region is the atmospheric circulation. Changes in atmospheric circulation modes and frequencies of circulation types have major impacts on temperature characteristics at a certain station or region. We present results of a statistical downscaling study focused on AP temperature variability showing both results of large-scale atmospheric circulation modes and regional weather type classifications derived from monthly and daily gridded reanalysis data sets. In order to investigate spatial trends and variabilities of the Southern Annular Mode (SAM), we analyze spatio-temporally resolved SAM-pattern maps from 1979 to 2015. First results show dominant multi-annual to decadal pattern variabilities which can be directly linked to temperature variabilities at the Antarctic Peninsula. A sub-continental to regional view on the influence of atmospheric circulation on AP temperature variability is given by the analysis of weather type classifications (WTC). With this analysis we identify significant changes in the frequency of occurrence of highly temperature-relevant circulation patterns. The investigated characteristics of weather type frequencies can also be related to the identified changes of the SAM.

Delineating gas bearing reservoir by using spectral decomposition attribute: Case study of Steenkool formation, Bintuni Basin

NASA Astrophysics Data System (ADS)

Haris, A.; Pradana, G. S.; Riyanto, A.

2017-07-01

Tectonic setting of the Bird Head Papua Island becomes an important model for petroleum system in Eastern part of Indonesia. The current exploration has been started since the oil seepage finding in Bintuni and Salawati Basin. The biogenic gas in shallow layer turns out to become an interesting issue in the hydrocarbon exploration. The hydrocarbon accumulation appearance in a shallow layer with dry gas type, appeal biogenic gas for further research. This paper aims at delineating the sweet spot hydrocarbon potential in shallow layer by applying the spectral decomposition technique. The spectral decomposition is decomposing the seismic signal into an individual frequency, which has significant geological meaning. One of spectral decomposition methods is Continuous Wavelet Transform (CWT), which transforms the seismic signal into individual time and frequency simultaneously. This method is able to make easier time-frequency map analysis. When time resolution increases, the frequency resolution will be decreased, and vice versa. In this study, we perform low-frequency shadow zone analysis in which the amplitude anomaly at a low frequency of 15 Hz was observed and we then compare it to the amplitude at the mid (20 Hz) and the high-frequency (30 Hz). The appearance of the amplitude anomaly at a low frequency was disappeared at high frequency, this anomaly disappears. The spectral decomposition by using CWT algorithm has been successfully applied to delineate the sweet spot zone.

Adolescent tobacco use practices and user profiles in a mature Swedish moist snuff (snus) market: Results from a school-based cross-sectional study.

PubMed

Lund, Ingeborg; Scheffels, Janne

2016-06-23

The aim of this work was to study the diversity of tobacco use among Norwegian adolescent tobacco users and to investigate how different user groups compared with each other in terms of lifestyle and risk correlates. Swedish moist snuff (snus) use has increased dramatically in Norway over the last few years and is now more prevalent than smoking in younger age groups. The participants were 736 15-year-old tobacco users obtained from a large school-based cross-sectional survey (response rate 73%). Leisure time activity and risk behaviour factors were extracted by principal components analysis. Associations between tobacco use, leisure activities, risk behaviours, alcohol use and sex were studied bivariately and by logistic regression. In total, 41.5% of the tobacco users were dual users (smokers and snus users). Problem behaviour and risk-taking lifestyles were associated with tobacco use frequency and high-frequency dual use, with a low risk profile for all types of occasional users (snus, cigarettes or dual users), a medium risk profile for all types of daily single-product users, including those who occasionally used the other product (i.e. dual users) and a high-risk profile for those who used both products daily (daily dual users). FRAGMENTED USE PATTERNS IN ADOLESCENCE UNDERMINE THE DICHOTOMY OFTEN APPLIED BETWEEN SMOKERS AND SNUS USERS FOR ASSOCIATIONS WITH LIFESTYLE AND RISK CORRELATES, USE FREQUENCY AND HIGH-FREQUENCY DUAL USE SEEM TO BE MORE IMPORTANT THAN THE CHOICE OF PRODUCT. © 2016 the Nordic Societies of Public Health.

PCR/oligonucleotide probe typing of HLA class II alleles in a Filipino population reveals an unusual distribution of HLA haplotypes

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

Bugawan, T.L.; Chang, J.D.; Erlich, H.A.

1994-02-01

The authors have analyzed the distribution of HLA class II alleles and haplotypes in a Filipino population by PCR amplification of the DRB1, DQB1, and DPB1 second-exon sequences from buccal swabs obtained from 124 family members and 53 unrelated individuals. The amplified DNA was typed by using nonradioactive sequence-specific oligonucleotide probes. Twenty-two different DRB1 alleles, including the novel Filipino *1105, and 46 different DRB1/DQB1 haplotypes, including the unusual DRB1*0405-DQB1*0503, were identified. An unusually high frequency (f = .383) of DPB1*0101, a rare allele in other Asian populations, was also observed. In addition, an unusual distribution of DRB1 alleles and haplotypesmore » was seen in this population, with DR2 (f = .415) and DRB1*1502-DQB1*0502 (f = .233) present at high frequencies. This distribution of DRB1 alleles differs from the typical HLA population distribution, in which the allele frequencies are more evenly balanced. The distribution of HLA class II alleles and haplotypes in this Filipino population is different from that of other Asian and Pacific groups: of those populations studied to date, the Indonesian population is the most similar. DRB1*1502-DQB1*0502 was in strong linkage disequilibrium (D[prime] = .41) with DPB 1*0101 (f = .126, for the extended haplotype), which is consistent with selection for this DR, DQ, DP haplotype being responsible for the high frequency of these three class II alleles in this populations. 30 refs., 2 figs., 6 tabs.« less

Genetic relationships in Cucurbita pepo (pumpkin, squash, gourd) as viewed with high frequency oligonucleotide–targeting active gene (HFO–TAG) markers

USDA-ARS?s Scientific Manuscript database

Cucurbita pepo is a highly diverse, economically important member of the Cucurbitaceae. C. pepo encompasses hundreds of cultivars of pumpkins, squash, and gourds. Although C. pepo has been scrutinized with various types of DNA markers, the relationships among the cultivar-groups of C. pepo subsp. p...

Double mushroom 1.55-μm waveguide photodetectors for integrated E-band (60-90 GHz) wireless transmitter modules

NASA Astrophysics Data System (ADS)

Rymanov, Vitaly; Tekin, Tolga; Stöhr, Andreas

2012-03-01

High data rate photonic wireless systems operating at millimeter wave carrier frequencies are considered as a disruptive technology e.g. for reach extension in optical access networks and for mobile backhauling. Recently, we demonstrated 60 GHz photonic wireless systems with record data rates up to 27 Gbit/s. Because of the oxygen absorption at 60 GHz, it is beneficial for fixed wireless systems with spans exceeding 1 km to operate at even higher frequencies. Here, the recently regulated 10 GHz bandwidth within the E-band (60-90 GHz) is of particular interest, covering the 71-76 GHz and 81-86 GHz allocations for multi-gigabit wireless transmission. For this purpose, wideband waveguide photodetectors with high external quantum efficiency are required. Here, we report on double mushroom 1.55 μm waveguide photodetectors for integration in an E-band wireless transmitter module. The developed photodetector consists of a partially p-doped, partly non-intentionally doped absorbing layer centered in a mushroom-type optical waveguide, overcoming the compromise between the junction capacitance and the series resistance. For efficient fiber-chip coupling, a second mushroom-type passive optical waveguide is used. In contrast to the conventional shallow ridge waveguide approach, the mushroom-type passive waveguide allows to shift the center of the optical mode further away from the top surface, thus reducing waveguide losses due to the surface roughness. Experimentally, a very flat frequency response with a deviation up to +/-1 dB in the entire E-band has been found together with an output power level of -15.7 dBm at 10 mA photocurrent and at a frequency of 73 GHz.

Microelectromechanical systems (MEMS) sensors based on lead zirconate titanate (PZT) films

NASA Astrophysics Data System (ADS)

Wang, Li-Peng

2001-12-01

In this thesis, modeling, fabrication and testing of microelectromechanical systems (MEMS) accelerometers based on piezoelectric lead zirconate titanate (PZT) films are investigated. Three different types of structures, cantilever beam, trampoline, and annular diaphragm, are studied. It demonstrates the high-performance, miniaturate, mass-production-compatible, and potentially circuitry-integratable piezoelectric-type PZT MEMS devices. Theoretical models of the cantilever-beam and trampoline accelerometers are derived via structural dynamics and the constitutive equations of piezoelectricity. The time-dependent transverse vibration equations, mode shapes, resonant frequencies, and sensitivities of the accelerometers are calculated through the models. Optimization of the silicon and PZT thickness is achieved with considering the effects of the structural dynamics, the material properties, and manufacturability for different accelerometer specifications. This work is the first demonstration of the fabrication of bulk-micromachined accelerometers combining a deep-trench reactive ion etching (DRIE) release strategy and thick piezoelectric PZT films deposited using a sol-gel method. Processing challenges which are overcome included materials compatibility, metallization, processing of thick layers, double-side processing, deep-trench silicon etching, post-etch cleaning and process integration. In addition, the processed PZT films are characterized by dielectric, ferroelectric (polarization electric-field hysteresis), and piezoelectric measurements and no adverse effects are found. Dynamic frequency response and impedance resonance measurements are performed to ascertain the performance of the MEMS accelerometers. The results show high sensitivities and broad frequency ranges of the piezoelectric-type PZT MEMS accelerometers; the sensitivities range from 0.1 to 7.6 pC/g for resonant frequencies ranging from 44.3 kHz to 3.7 kHz. The sensitivities were compared to theoretical values and a reasonable agreement (˜36% difference) is obtained.

Influence of Sm doping on structural and dielectric properties of Y{sub 1-x}Sm{sub x}MnO{sub 3} (x = 0, 0.10, 0.20) manganites

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

Dar, Mashkoor Ahmad, E-mail: darmashkoor.phst@gmail.com; Dar, Hilal Ahmad; Varshney, Dinesh, E-mail: vdinesh33@rediffmail.com

2016-05-06

Structural and dielectric properties of polycrystalline YMnO{sub 3} (x = 0.0, 0.10 and 0.20) which was prepared by solid-state reaction route, have been investigated. The X-ray diffraction pattern reveals that all the samples are in single phase and show hexagonal structure with P63cm space group. The particle size decreases with increase in Sm doping while to that X-ray density increases with increasing x. The dielectric constant (ε’) of Y{sub 1-x}Sm{sub x}MnO{sub 3} measured in the frequency range 10 Hz to 1MHz is much higher at lower frequencies (≤ 1KHz) and its value decreases with enhanced frequency. At very high frequencies, ε’more » becomes frequency independent and is attributed to Maxwell Wagner type of interfacial polarization model. A very high value of dielectric constant ∼18642 is observed for x = 10%. The dielectric loss (tan δ) decreases wit increase in Sm doping.« less

Wave forcing and morphological changes of New Caledonia lagoon islets: Insights on their possible relations

NASA Astrophysics Data System (ADS)

Aucan, Jérôme; Vendé-Leclerc, Myriam; Dumas, Pascal; Bricquir, Marianne

2017-10-01

In the present study, we examine how waves may contribute to the morphological changes of islets in the New Caledonia lagoon. We collected in situ wave data to investigate their characteristics. Three types of waves are identified and quantified: (1) high-frequency waves generated within the lagoon, (2) low-frequency waves originating from swells in the Tasman Sea, and (3) infragravity waves. We found out that high-frequency waves are the dominant forcing on the islets during typical wind events throughout the year, while infragravity waves, likely generated by the breaking of low-frequency waves, dominate during seasonal swell events. During swell events, low-frequency waves can also directly propagate to the islets through channels across the barrier reef, or be tidally modulated across the barrier reef before reaching the islets. Topographic surveys and beach profiles on one islet indicate areas with seasonal morphological changes and other areas with longer, interannual or decadal, erosion patterns. Although more data are needed to validate this hypothesis, we suspect that a relation exists between wave forcing and morphological changes of the islets.

Modeling and performance of HF/OTH (High-Frequency/Over-the-Horizon) radar target identification systems

NASA Astrophysics Data System (ADS)

Strausberger, Donald J.

Several Radar Target Identification (RTI) techniques have been developed at The Ohio State University in recent years. Using the ElectroScience Laboratory compact range a large database of coherent RCS measurement has been constructed for several types of targets (aircraft, ships, and ground vehicles) at a variety of polarizations, aspect angles, and frequency bands. This extensive database has been used to analyze the performance of several different classification algorithms through the use of computer simulations. In order to optimize classification performance, it was concluded that the radar frequency range should lie in the Rayleigh-resonance frequency range, where the wavelength is on the order of or larger than the target size. For aircraft and ships with general dimensions on the order of 10 meters to 100 meters it is apparent that the High Frequency (HF) band provides optimal classification performance. Since existing HF radars are currently being used for detection and tracking or aircraft and ships of these dimensions, it is natural to further investigate the possibility of using these existing radars as the measurement devices in a radar target classification system.

Multivariate analysis of correlation between electrophysiological and hemodynamic responses during cognitive processing

PubMed Central

Kujala, Jan; Sudre, Gustavo; Vartiainen, Johanna; Liljeström, Mia; Mitchell, Tom; Salmelin, Riitta

2014-01-01

Animal and human studies have frequently shown that in primary sensory and motor regions the BOLD signal correlates positively with high-frequency and negatively with low-frequency neuronal activity. However, recent evidence suggests that this relationship may also vary across cortical areas. Detailed knowledge of the possible spectral diversity between electrophysiological and hemodynamic responses across the human cortex would be essential for neural-level interpretation of fMRI data and for informative multimodal combination of electromagnetic and hemodynamic imaging data, especially in cognitive tasks. We applied multivariate partial least squares correlation analysis to MEG–fMRI data recorded in a reading paradigm to determine the correlation patterns between the data types, at once, across the cortex. Our results revealed heterogeneous patterns of high-frequency correlation between MEG and fMRI responses, with marked dissociation between lower and higher order cortical regions. The low-frequency range showed substantial variance, with negative and positive correlations manifesting at different frequencies across cortical regions. These findings demonstrate the complexity of the neurophysiological counterparts of hemodynamic fluctuations in cognitive processing. PMID:24518260

Evidence of Paternal N5, N10 - Methylenetetrahydrofolate Reductase (MTHFR) C677T Gene Polymorphism in Couples with Recurrent Spontaneous Abortions (RSAs) in Kolar District- A South West of India

PubMed Central

Vanilla, Shiny; Kotur, Pushpa F; Kutty, Moideen A; Vegi, Pradeep Kumar

2015-01-01

Introduction: Recurrent spontaneous abortion (RSA) is a multifactorial clinical obstetrics complication commonly occurring in pregnancy. Many research studies have noted the mutations such as C677T in N5, N10 - Methylenetetrahydrofolate reductase (MTHFR)gene which is regarded as RSA risk factor. This study was carried out to determine the occurrence of frequency of C677T of the MTHFR gene mutations with RSA. Aim: The purpose of present study is to determine the frequency of MTHFR C677T polymorphisms in couples with recurrent pregnancy loss and the impact of paternal polymorphisms of MTHFR C677T in recurrent pregnancy loss in population of couples living in Kolar district of Karnataka with RSA. Design: A total of 15 couples with a history of two or more unexplained RSA were enrolled as subjects in the study and a total of 15 couples with normal reproductive history, having two or more children and no history of miscarriages were enrolled as controls. Materials and Methods: DNA extraction from samples case and control group couples and its quantification by Agarose gel electrophoresis, assessment of DNA purity, MTHFR C 677T gene mutation detection by PCR-RFLP method. Statistical analysis: Carried out by web based online SPSS tool. Results: The frequency of C677T genotype showed homozygous wild type CC (80%), heterozygous CT type (13.3%) and homozygous mutation TT type (6.67%) observed in males. Similarly from female’s homozygous wild type CC (86.6%), heterozygous type (13.3%), and homozygous type mutations TT (0%) was recorded. In couple control groups, we observed homozygous wild type CC (86.6%), heterozygous CT type (13.3%) and homozygous type mutations TT type (0%). Conclusion: We noticed a high frequency of MTHFR specifically T allele associated with paternal side.Therefore, the present study indicated the impact of paternal gene polymorphism of MTHFR C677T on screening in couples with recurrent pregnancy loss. PMID:25859445

The effect of changing disk parameters on whirling frequency of high speed rotor system

NASA Astrophysics Data System (ADS)

Wahab, A. M. Abdul; Rasid, Z. A.; Abu, A.; Rudin, N. F. Mohd Noor; Yakub, F.

2017-12-01

The requirement for efficiency improvement of machines has caused machine rotor to be designed to rotate at high speeds. It is known that whirling natural frequency of a shaft changes with the change of shaft speed and the design needs to avoid points of resonance where the whirling frequency equals the shaft speed. At high speeds, a shaft may have to carry a huge torque along and this torsional effect has been neglected in past shaft analyses. Whirling behaviour of high speed rotating shaft is investigated in this study with consideration of the torsional effect of the shaft. The shaft system under study consists of a shaft, discs and two bearings, and the focus is on the effect of the disc parameters. A finite element formulation is developed based on Nelson’s 5 degrees of freedom (DOF) per node element that includes the torsional degree of freedom. Bolotin’s method is applied to the derived Mathieu-Hill type of equation to get quadratic eigenvalues problem that gives the forward and backward frequencies of the shaft. Campbell’s diagrams are drawn in studying the effect of discs on the whirling behaviour of the shaft. It is found that the addition of disks on the shaft decreases the whirling frequency of the shaft and the frequency is lower for mass located at the centre of the shaft compared to the one located near to the end. The effect of torsional motion is found to be significant where the difference between critical speed of 4DOF and 5DOF models can be as high as 15%.

Poor adherence to treatment associated with a high recurrence in a bipolar disorder outpatient sample.

PubMed

Gutiérrez-Rojas, Luis; Jurado, Dolores; Martínez-Ortega, José María; Gurpegui, Manuel

2010-12-01

We analyzed the association of previous course-of-illness and other variables of clinical interest with a high frequency of both depressive or (hypo)manic episodes controlling for the effect of socio-demographic characteristics. A total of 108 outpatients with a DSM-IV diagnosis of bipolar disorder (BD) were recruited. A retrospective and naturalistic study was conducted to examine the number of affective episodes and their relationship with socio-demographic, clinical and course-of-illness variables, including adherence to medication, type of medication used and the use of addictive substances. The episode frequency was estimated as the number of "major instances" of depression, hypomania and mania during the illness. To classify the patients into two groups (higher and lower-episode frequency), we used the statistical criterion of median split. Results were analyzed with logistic regression models to control for the effects of potential confounders. A high episode frequency (nine or more episodes) was associated with age (36-55years), delay in diagnosis, poor adherence to medication and current use of antipsychotic medication. In addition, a high frequency of manic episodes (four or more) was associated with female sex, age (>36years) and a manic onset of the illness, whereas a high frequency of depressive episodes (five or more) was associated with delay in diagnosis and poor adherence to medication. Cross-sectional study design. Avoiding delay in diagnosis and enhancing treatment adherence might be important targets for reducing recurrences in BD. Copyright © 2010 Elsevier B.V. All rights reserved.

Induction of pure and sectored mutant clones in excision-proficient and deficient strains of yeast.

PubMed

Eckardt, F; Haynes, R H

1977-06-01

We have found that UV-induced mutation frequency in a forward non-selective assay system (scoring white adex ade2 double auxotroph mutants among the red pigmented ade2 clones) increases linearly with dose up to a maximum frequency of about 3 X 10(-3) mutants per survivor and then declines in both RAD wild-type and rad2 excision deficient strains of Saccharomyces cerevisiae. Mutation frequencies of the RAD and the rad2 strains plotted against survival are nearly identical over the entire survival range. On this basis we conclude that unexcised pyrimidine dimers are the predominant type of pre-mutational lesions in both strains. In the RAD wild-type strain pure mutant clones outnumber sectors in a 10:1 ratio at all doses used; in rad2 this ratio varies from 1:1 at low doses up to 10:1 at high doses. As others have concluded for wild-type strains we find also in the rad2 strain that pure clone formation cannot be accounted for quantitatively by lethal sectoring events alone. We conclude that heteroduplex repair is a crucial step in pure mutant clone formation and we examine the plausibility of certain macromolecular mechanisms according to which heteroduplex repair may be coupled with replication, repair and sister strand exchange in yeast mutagenesis.

High Resolution Human Leukocyte Antigen Class I Allele Frequencies and HIV-1 Infection Associations in Chinese Han and Uyghur Cohorts

PubMed Central

Liu, Yanhou; Zhao, Zhongfang; Li, Tianyi; Liao, Qi; Kushner, Nicholas; Touzjian, Neal Y.; Shao, Yiming; Sun, Yongtao; Strong, Amie J.; Lu, Yichen

2012-01-01

Background Host immunogenetic factors such as HLA class I polymorphism are important to HIV-1 infection risk and AIDS progression. Previous studies using high-resolution HLA class I profile data of Chinese populations appeared insufficient to provide information for HIV-1 vaccine development and clinical trial design. Here we reported HLA class I association with HIV-1 susceptibility in a Chinese Han and a Chinese Uyghur cohort. Methodology/Principal Findings Our cohort included 327 Han and 161 Uyghur ethnic individuals. Each cohort included HIV-1 seropositive and HIV-1 seronegative subjects. Four-digit HLA class I typing was performed by sequencing-based typing and high-resolution PCR-sequence specific primer. We compared the HLA class I allele and inferred haplotype frequencies between HIV-1 seropositive and seronegative groups. A neighbor-joining tree between our cohorts and other populations was constructed based on allele frequencies of HLA-A and HLA-B loci. We identified 58 HLA-A, 75 HLA-B, and 32 HLA-Cw distinct alleles from our cohort and no novel alleles. The frequency of HLA-B*5201 and A*0301 was significantly higher in the Han HIV-1 negative group. The frequency of HLA-B*5101 was significantly higher in the Uyghur HIV-1 negative group. We observed statistically significant increases in expectation-maximization (EM) algorithm predicted haplotype frequencies of HLA-A*0201-B*5101 in the Uyghur HIV-1 negative group, and of Cw*0304-B*4001 in the Han HIV-1 negative group. The B62s supertype frequency was found to be significantly higher in the Han HIV-1 negative group than in the Han HIV-1 positive group. Conclusions At the four-digit level, several HLA class I alleles and haplotypes were associated with lower HIV-1 susceptibility. Homogeneity of HLA class I and Bw4/Bw6 heterozygosity were not associated with HIV-1 susceptibility in our cohort. These observations contribute to the Chinese HLA database and could prove useful in the development of HIV-1 vaccine candidates. PMID:23251376

On the Nature of the mHz X-Ray QPOs from ULX M82 X-1: Evidence for Timing-Spectral (anti) Correlation

NASA Technical Reports Server (NTRS)

Pasham, Dheeraj R.; Strohmayer, Tod E.

2013-01-01

Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1 we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its energy spectral power-law index. These quantities are known to correlate in stellar mass black holes (StMBHs) exhibiting Type-C QPOs (approx 0.2-15 Hz). The detection of such a correlation would strengthen the identification of its mHz QPOs as Type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of Type-C QPOs in StMBHs of known mass. We resolved the count rates of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling and identify observations in which M82 X-1 was at least as bright as source 5. Using only those observations, we detect QPOs in the frequency range of 36-210 mHz during which the energy spectral power-law index varied from 1.7-2.2. Interestingly, we find evidence for an anti-correlation (Pearsons correlation coefficient = -0.95) between the power-law index and the QPO centroid frequency. While such an anti-correlation is observed in StMBHs at high Type-C QPO frequencies (approx 5-15 Hz), the frequency range over which it holds in StMBHs is significantly smaller (factor of approx 1.5-3) than the QPO range reported here from M82 X-1 (factor of 6). However, it remains possible that contamination from source 5 can bias our result. Joint Chandra/XMM-Newton observations in the future can resolve this problem and confirm the timing-spectral anti-correlation reported here.

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.

Quantum-limited detection of millimeter waves using superconducting tunnel junctions

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

Mears, Carl Atherton

1991-09-01

The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit bymore » studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 ± 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker`s theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs.« less

Quantum-limited detection of millimeter waves using superconducting tunnel junctions

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

Mears, C.A.

1991-09-01

The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit bymore » studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 {plus minus} 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker's theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs.« less

Health Issues: Do Cell Phones Pose a Health Hazard?

MedlinePlus

... confused with the effects from other types of electromagnetic energy. Very high levels of electromagnetic energy, such as is found in X-rays ... light, infrared radiation (heat) and other forms of electromagnetic radiation with relatively low frequencies. While RF energy ...

The population genetics of human disease: The case of recessive, lethal mutations

PubMed Central

Gao, Ziyue; Baker, Zachary; Diesel, José Francisco; Simons, Yuval B.; Haque, Imran S.; Pickrell, Joseph; Przeworski, Molly

2017-01-01

Do the frequencies of disease mutations in human populations reflect a simple balance between mutation and purifying selection? What other factors shape the prevalence of disease mutations? To begin to answer these questions, we focused on one of the simplest cases: recessive mutations that alone cause lethal diseases or complete sterility. To this end, we generated a hand-curated set of 417 Mendelian mutations in 32 genes reported to cause a recessive, lethal Mendelian disease. We then considered analytic models of mutation-selection balance in infinite and finite populations of constant sizes and simulations of purifying selection in a more realistic demographic setting, and tested how well these models fit allele frequencies estimated from 33,370 individuals of European ancestry. In doing so, we distinguished between CpG transitions, which occur at a substantially elevated rate, and three other mutation types. Intriguingly, the observed frequency for CpG transitions is slightly higher than expectation but close, whereas the frequencies observed for the three other mutation types are an order of magnitude higher than expected, with a bigger deviation from expectation seen for less mutable types. This discrepancy is even larger when subtle fitness effects in heterozygotes or lethal compound heterozygotes are taken into account. In principle, higher than expected frequencies of disease mutations could be due to widespread errors in reporting causal variants, compensation by other mutations, or balancing selection. It is unclear why these factors would have a greater impact on disease mutations that occur at lower rates, however. We argue instead that the unexpectedly high frequency of disease mutations and the relationship to the mutation rate likely reflect an ascertainment bias: of all the mutations that cause recessive lethal diseases, those that by chance have reached higher frequencies are more likely to have been identified and thus to have been included in this study. Beyond the specific application, this study highlights the parameters likely to be important in shaping the frequencies of Mendelian disease alleles. PMID:28957316

Experimental Study on an Unsteady Pressure Gain Combustion Hypergolic Rocket Engine Concept

NASA Astrophysics Data System (ADS)

Kan, Brandon K.

An experimental study is conducted to investigate pulsed combustion in a lab-scale bipropellant rocket engine using hypergolic propellants. The propellant combination is high concentration hydrogen peroxide and a catalyst-laced triglyme fuel. A total of 50 short duration firings have been conducted; the vast majority in an open-chamber configuration. High amplitude pulsations were evident in nearly all cases and have been assessed with high frequency pressure measurements. Both pintle and unlike impinging quadlet injector types have been evaluated although the bulk of the testing was with the latter configuration. Several firings were conducted with a transparent chamber in an attempt to gain understanding using a high-speed camera in the visible spectrum. Peak chamber pressures in excess of 5000 psi have been recorded with surface mounted high frequency gages with pulsation frequencies exceeding 600 Hz. A characterization of time-averaged performance is made for the unsteady system, where time-resolved thrust and pressure measurements were attempted. While prior literature describes this system as a pulse detonation rocket engine, the combustion appears to be more "constant volume" in nature.

Design and simulation of RF MEMS SPST shunt and SPDT shunt-shunt switches for X-band and Ku-band applications

NASA Astrophysics Data System (ADS)

Lenka, Manas K.; Sharma, Amit; Sharma, Jaibir; DasGupta, Amitava

2012-10-01

This paper describes the design and simulation of RF MEMS SPST shunt and SPDT shunt-shunt switches with modified coplanar waveguide (CPW) configuration for X-band and Ku-band applications exhibiting high isolation and low insertion loss. By modifying the basic CPW structure for a six-strip membrane having length 720 μm, the resonant frequency can be reduced from 33.5 GHz to 13.5 GHz with isolation as high as -30 dB(-63 dB at resonant frequency) in Ku-band. Similar results are also found in case SPST and SPDT switches with other membrane types.

High-power waveguide resonator second harmonic device with external conversion efficiency up to 75%

NASA Astrophysics Data System (ADS)

Stefszky, M.; Ricken, R.; Eigner, C.; Quiring, V.; Herrmann, H.; Silberhorn, C.

2018-06-01

We report on a highly efficient waveguide resonator device for the production of 775 nm light using a titanium indiffused LiNbO3 waveguide resonator. When scanning the resonance, the device produces up to 110 mW of second harmonic power with 140 mW incident on the device—an external conversion efficiency of 75%. The cavity length is also locked, using a Pound–Drever–Hall type locking scheme, involving feedback to either the cavity temperature or the laser frequency. With laser frequency feedback, a stable output power of approximately 28 mW from a 52 mW pump is seen over one hour.

[Autoaggression and pulse rate--a longitudinal study].

PubMed

Rohmann, U H; Elbing, U; Hartmann, H

1988-12-01

This article presents a model of autoaggressive behavior in which a distinction is made between determining and maintaining factors. Specific environmental, in particular social, and organismic variables are linked to them. The two types of variables interact, thus causing or maintaining autoaggressive behavior. A theory of autoaggression must therefore rely on multicausal/multimodal explanations. A connection between autoaggression and a high level of arousal suggests itself. In this single-case longitudinal study a comparison was made between heart rate and frequency of autoaggressive behavior. High heart rates were found to be correlated with low frequencies of autoaggressive behavior and vice versa. Decreasing autoaggressive behavior was coupled with increasing muscle relaxation and increasing motor activity. However, abnormally high heart rates were associated with both low and high levels of motor activity.

CFD modeling and experimental verification of oscillating flow and heat transfer processes in the micro coaxial Stirling-type pulse tube cryocooler operating at 90-170 Hz

NASA Astrophysics Data System (ADS)

Zhao, Yibo; Yu, Guorui; Tan, Jun; Mao, Xiaochen; Li, Jiaqi; Zha, Rui; Li, Ning; Dang, Haizheng

2018-03-01

This paper presents the CFD modeling and experimental verifications of oscillating flow and heat transfer processes in the micro coaxial Stirling-type pulse tube cryocooler (MCSPTC) operating at 90-170 Hz. It uses neither double-inlet nor multi-bypass while the inertance tube with a gas reservoir becomes the only phase-shifter. The effects of the frequency on flow and heat transfer processes in the pulse tube are investigated, which indicates that a low enough frequency would lead to a strong mixing between warm and cold fluids, thereby significantly deteriorating the cooling performance, whereas a high enough frequency would produce the downward sloping streams flowing from the warm end to the axis and almost puncturing the gas displacer from the warm end, thereby creating larger temperature gradients in radial directions and thus undermining the cooling performance. The influence of the pulse tube length on the temperature and velocity when the frequencies are much higher than the optimal one are also discussed. A MCSPTC with an overall mass of 1.1 kg is worked out and tested. With an input electric power of 59 W and operating at 144 Hz, it achieves a no-load temperature of 61.4 K and a cooling capacity of 1.0 W at 77 K. The changing tendencies of tested results are in good agreement with the simulations. The above studies will help to thoroughly understand the underlying mechanism of the inertance MCSPTC operating at very high frequencies.

Evaluation of Hearing Loss in Pilots

PubMed Central

Atalay, Hayriye; Babakurban, Seda Türkoğlu; Aydın, Erdinç

2015-01-01

Objective High-intensity noise sources with an increase in air traffic and sudden changes in atmospheric pressure can cause hearing loss in pilots. The main goal of this research is to examine hearing loss due to age, the total flight hours and aircraft types and to evaluate the effects of personal conditions that can influence the hearing level. Methods We examined the data of 234 Turkish pilots aged between 25 and 54 years who were examined due to the aviation Law for annual control from January 2005 to January 2014 at Başkent University Medical Faculty, Ankara Hospital. The audiometric results of the pilots were used. While 1, 2, 3, 4, 6, and 8 KHz were used for the airway threshold, 1, 2, and 4 KHz were used for the bone conduction threshold. Results According to the data of the 234 pilots, there was a significant correlation between high-frequency hearing loss and the total flight hours and pilots’ ages. The average hearing loss was higher, particularly in the left ear, in pilots using helicopters than in those using other aircraft types. There was no statistically significant correlation between hearing loss and diabetes, hypercholesterolemia, high blood pressure, anemia, obesity, and smoking. Conclusion A significant correlation was observed between high frequency hearing loss and the total flight hours, pilots’ age, and aircraft types in our study. PMID:29392000

Noise in solid-state nanopores

PubMed Central

Smeets, R. M. M.; Keyser, U. F.; Dekker, N. H.; Dekker, C.

2008-01-01

We study ionic current fluctuations in solid-state nanopores over a wide frequency range and present a complete description of the noise characteristics. At low frequencies (f ≲ 100 Hz) we observe 1/f-type of noise. We analyze this low-frequency noise at different salt concentrations and find that the noise power remarkably scales linearly with the inverse number of charge carriers, in agreement with Hooge's relation. We find a Hooge parameter α = (1.1 ± 0.1) × 10−4. In the high-frequency regime (f ≳ 1 kHz), we can model the increase in current power spectral density with frequency through a calculation of the Johnson noise. Finally, we use these results to compute the signal-to-noise ratio for DNA translocation for different salt concentrations and nanopore diameters, yielding the parameters for optimal detection efficiency. PMID:18184817

Noise in solid-state nanopores.

PubMed

Smeets, R M M; Keyser, U F; Dekker, N H; Dekker, C

2008-01-15

We study ionic current fluctuations in solid-state nanopores over a wide frequency range and present a complete description of the noise characteristics. At low frequencies (f approximately < 100 Hz) we observe 1/f-type of noise. We analyze this low-frequency noise at different salt concentrations and find that the noise power remarkably scales linearly with the inverse number of charge carriers, in agreement with Hooge's relation. We find a Hooge parameter alpha = (1.1 +/- 0.1) x 10(-4). In the high-frequency regime (f approximately > 1 kHz), we can model the increase in current power spectral density with frequency through a calculation of the Johnson noise. Finally, we use these results to compute the signal-to-noise ratio for DNA translocation for different salt concentrations and nanopore diameters, yielding the parameters for optimal detection efficiency.

Frequency and mode identification of γ Doradus from photometric and spectroscopic observations*

NASA Astrophysics Data System (ADS)

Brunsden, E.; Pollard, K. R.; Wright, D. J.; De Cat, P.; Cottrell, P. L.

2018-04-01

The prototype star for the γ Doradus class of pulsating variables was studied employing photometric and spectroscopic observations to determine the frequencies and modes of pulsation. The four frequencies found are self-consistent between the observation types and almost identical to those found in previous studies (1.3641 d-1, 1.8783 d-1, 1.4742 d-1, and 1.3209 d-1). Three of the frequencies are classified as l, m = (1, 1) pulsations and the other is ambiguous between l, m = (2, 0) and (2, -2) modes. Two frequencies are shown to be stable over 20 yr since their first identification. The agreement in ground-based work makes this star an excellent calibrator between high-precision photometry and spectroscopy with the upcoming TESS observations and a potential standard for continued asteroseismic modelling.

A solid state converter for measurement of aircraft noise and sonic boom

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J.

1972-01-01

The problems inherent in present systems of instrumentation for measuring aircraft noise and sonic boom include limited frequency response, expensive connecting cables, sensitivity to cable length and type, high sensitivity to environmental conditions, and additional limitations of individual system components. Furthermore, differing requirements have resulted in the use of two different systems for aircraft noise and sonic boom measurements respectively. To alleviate these difficulties a unified system of instrumentation suitable for both types of measurements was developed. The system features a new solid state converter connected to a zero drive amplifier. The system was found insensitive to cable length and type up to at least 1000 ft and requires no impedance matching networks. The converter itself has flat frequency response from dc to 28 kHz (- 3 db), dynamic range of 72 db, and noise floor of 50 db in the band 22.4 Hz to 22.4 kHz.

Medium-high frequency FBG accelerometer with integrative matrix structure.

PubMed

Dai, Yutang; Yin, Guanglin; Liu, Bin; Xu, Gang; Karanja, Joseph Muna

2015-04-10

To meet the requirements for medium-high frequency vibration monitoring, a new type fiber Bragg grating (FBG) accelerometer with an integrative matrix structure is proposed. Two symmetrical flexible gemels are used as elastic elements, which drive respective inertial mass moving reversely when exciting vibration exists, leading to doubling the wavelength shift of the FBG. The mechanics model and a numerical method are presented in this paper, by which the influence of the structural parameters on the sensitivity and eigenfrequency is discussed. Sensitivity higher than 200  pm/g and an eigenfrequency larger than 3000 Hz can be realized separately, but both cannot be achieved simultaneously. Aiming for a broader measuring frequency range, a prototype accelerometer with an eigenfrequency near 3000 Hz is designed, and results from a shake table test are also demonstrated.

Invariants of electromechanical coupling coefficients in piezoceramics.

PubMed

Mezheritsky, Alex V

2003-12-01

The relationships between coefficients of electromechanical coupling (CEMC) of various types of piezoceramic resonator (PR) vibrations are considered. Being constant for a given piezoceramic state, the range of variation of piezoceramics dielectric permittivity from a mechanically "free" condition at relatively low frequencies up to an "overall clamped" condition at high frequencies is determined by a consecutive "clamping", caused by a complex of CEMCs of various particular vibrational modes peculiar to the resonator. As the difference between "free" and "overall clamped" permittivities is always determined by the maximal piezomaterial ki3 coupling coefficient, the difference does not depend on the path that was gone through the low-high frequency range, which includes all the vibrational modes possible for a particular PR. The influence of the piezoelectric and elastic anisotropy of lead-zirconate-titanate (PZT) piezoceramic materials on relative CEMC variations was experimentally investigated.

A basic study on universal design of auditory signals in automobiles.

PubMed

Yamauchi, Katsuya; Choi, Jong-dae; Maiguma, Ryo; Takada, Masayuki; Iwamiya, Shin-ichiro

2004-11-01

In this paper, the impression of various kinds of auditory signals currently used in automobiles and a comprehensive evaluation were measured by a semantic differential method. The desirable acoustic characteristic was examined for each type of auditory signal. Sharp sounds with dominant high-frequency components were not suitable for auditory signals in automobiles. This trend is expedient for the aged whose auditory sensitivity in the high frequency region is lower. When intermittent sounds were used, a longer OFF time was suitable. Generally, "dull (not sharp)" and "calm" sounds were appropriate for auditory signals. Furthermore, the comparison between the frequency spectrum of interior noise in automobiles and that of suitable sounds for various auditory signals indicates that the suitable sounds are not easily masked. The suitable auditory signals for various purposes is a good solution from the viewpoint of universal design.

Microscale 1-3-Type (Na,K)NbO(3)-Based Pb-Free Piezocomposites for High-Frequency Ultrasonic Transducer Applications.

PubMed

Shen, Zong-Yang; Li, Jing-Feng; Chen, Ruimin; Zhou, Qifa; Shung, K Kirk

2011-05-01

Fine-grained Pb-free (Na(0.535)K(0.485))(0.95)Li(0.05)(Nb(0.8)Ta(0.2))O(3) (NKLNT) piezoceramics prepared by spark plasma sintering (SPS) technique was used to fabricate NKLNT/epoxy 1-3 composites with a modified dice-fill method. Because of its good machinability, SPSed NKLNT ceramic rods could be miniaturized to a lateral width of 50 µm. After lapping down to 56 µm in thickness, the composite was used to fabricate an ultrasonic transducer as the active piezoelectric element. This composite transducer showed a bandwidth at -6 dB nearly 90%at a center frequency of 29 MHz, demonstrating that this Pb-free composite thick film is very promising for the fabrication of high-frequency ultrasonic transducers in medical imaging applications.

High frequency plasma generator for ion thrusters

NASA Technical Reports Server (NTRS)

Goede, H.; Divergilio, W. F.; Fosnight, V. V.; Komatsu, G.

1984-01-01

The results of a program to experimentally develop two new types of plasma generators for 30 cm electrostatic argon ion thrusters are presented. The two plasma generating methods selected for this study were by radio frequency induction (RFI), operating at an input power frequency of 1 MHz, and by electron cyclotron heating (ECH) at an operating frequency of 5.0 GHz. Both of these generators utilize multiline cusp permanent magnet configurations for plasma confinement and beam profile optimization. The program goals were to develop a plasma generator possessing the characteristics of high electrical efficiency (low eV/ion) and simplicity of operation while maintaining the reliability and durability of the conventional hollow cathode plasma sources. The RFI plasma generator has achieved minimum discharge losses of 120 eV/ion while the ECH generator has obtained 145 eV/ion, assuming a 90% ion optical transparency of the electrostatic acceleration system. Details of experimental tests with a variety of magnet configurations are presented.

Molecular identification of rare FY*Null and FY*X alleles in Caucasian thalassemic family from Sardinia.

PubMed

Manfroi, Silvia; Scarcello, Antonio; Pagliaro, Pasqualepaolo

2015-10-01

Molecular genetic studies on Duffy blood group antigens have identified mutations underlying rare FY*Null and FY*X alleles. FY*Null has a high frequency in Blacks, especially from sub-Saharan Africa, while its frequency is not defined in Caucasians. FY*X allele, associated with Fy(a-b+w) phenotype, has a frequency of 2-3.5% in Caucasian people while it is absent in Blacks. During the project of extensive blood group genotyping in patients affected by hemoglobinopathies, we identified FY*X/FY*Null and FY*A/FY*Null genotypes in a Caucasian thalassemic family from Sardinia. We speculate on the frequency of FY*X and FY*Null alleles in Caucasian and Black people; further, we focused on the association of FY*X allele with weak Fyb antigen expression on red blood cells and its identification performing high sensitivity serological typing methods or genotyping. Copyright © 2015 Elsevier Ltd. All rights reserved.

Manufacturing Technology Study on Radio Frequency Power Modules Packaging Techniques.

DTIC Science & Technology

1981-01-01

compromised; in most cases, it was found to be higher than our original process. An accelerated high 125 I temperature aging test was performed to attain...sealing glasses without some oxynen. Alternatively, there are many high temperature amorphous type glasses which satisfactorily fire in nitrogen but...achieve some degree of crystalization when fired at high temperature . In using the high temperatures (900°C range) the effect on the previously printed

Using snowflake surface-area-to-volume ratio to model and interpret snowfall triple-frequency radar signatures

NASA Astrophysics Data System (ADS)

Gergely, Mathias; Cooper, Steven J.; Garrett, Timothy J.

2017-10-01

The snowflake microstructure determines the microwave scattering properties of individual snowflakes and has a strong impact on snowfall radar signatures. In this study, individual snowflakes are represented by collections of randomly distributed ice spheres where the size and number of the constituent ice spheres are specified by the snowflake mass and surface-area-to-volume ratio (SAV) and the bounding volume of each ice sphere collection is given by the snowflake maximum dimension. Radar backscatter cross sections for the ice sphere collections are calculated at X-, Ku-, Ka-, and W-band frequencies and then used to model triple-frequency radar signatures for exponential snowflake size distributions (SSDs). Additionally, snowflake complexity values obtained from high-resolution multi-view snowflake images are used as an indicator of snowflake SAV to derive snowfall triple-frequency radar signatures. The modeled snowfall triple-frequency radar signatures cover a wide range of triple-frequency signatures that were previously determined from radar reflectivity measurements and illustrate characteristic differences related to snow type, quantified through snowflake SAV, and snowflake size. The results show high sensitivity to snowflake SAV and SSD maximum size but are generally less affected by uncertainties in the parameterization of snowflake mass, indicating the importance of snowflake SAV for the interpretation of snowfall triple-frequency radar signatures.

Effect of frequency-doubling pulse Nd:YAG laser on microbial mutation

NASA Astrophysics Data System (ADS)

Zhao, Yansheng; Wang, Luyan; Zheng, Heng; Yin, Hongping; Chen, Xiangdong; Tan, Zheng; Wu, Wutong

1999-09-01

We are going to report the mutagenic effect of frequency-doubling pulse Nd:YAG laser (532 nm) on microbe. After irradiation with pulse laser, mutants of abscisic acid producing strains and erythromycin producing strains were obtained, one of which could produce 62.1% and 57% more products than control, respectively. In the study of mutagenization of Spirulina platensis caused by pulse laser, we selected a high photosynthetic strains, with improved productivity of protein and exocellular ploysaccharides of 12% and 246%, respectively. The experimental results indicate that frequency-doubling pulse laser (532 nm) is a potential new type of physical mutagenic factor.

Oscillation spectrum of WASP-33 from the MOST photometry

NASA Astrophysics Data System (ADS)

Mkrtichian, David

2015-08-01

We present results of extended continuous time series photometry of the Delta Scuti type pulsating exoplanet host star WASP-33 obtained in two seasons (2011 and 2013) with the MOST space telescope. Our frequency analysis yealds rich, low-amplitude multi-frequency spectrum of oscillation modes. We discuss possible resonances between the orbiital period of the planet and frequencies of the oscillation modes. We present results of our measurements of planets orbital O-C variations and analyze possible existence of invisible planets in the system. We review recent results of the high-resolution spectroscopic campaign on WASP-33 and confirm the retrograde orbital motion of the planet WASP-33b.

Expansion of the Knockdown Resistance Frequency Map for Human Head Lice (Phthiraptera: Pediculidae) in the United States Using Quantitative Sequencing.

PubMed

Gellatly, Kyle J; Krim, Sarah; Palenchar, Daniel J; Shepherd, Katie; Yoon, Kyong Sup; Rhodes, Christopher J; Lee, Si Hyeock; Marshall Clark, J

2016-05-01

Pediculosis is a prevalent parasitic infestation of humans, which is increasing due, in part, to the selection of lice resistant to either the pyrethrins or pyrethroid insecticides by the knockdown resistance (kdr) mechanism. To determine the extent and magnitude of the kdr-type mutations responsible for this resistance, lice were collected from 138 collection sites in 48 U.S. states from 22 July 2013 to 11 May 2015 and analyzed by quantitative sequencing. Previously published data were used for comparisons of the changes in the frequency of the kdr-type mutations over time. Mean percent resistance allele frequency (mean % RAF) values across the three mutation loci were determined from each collection site. The overall mean % RAF (±SD) for all analyzed lice was 98.3 ± 10%. 132/138 sites (95.6%) had a mean % RAF of 100%, five sites (3.7%) had intermediate values, and only a single site had no mutations (0.0%). Forty-two states (88%) had a mean % RAF of 100%. The frequencies of kdr-type mutations did not differ regardless of the human population size that the lice were collected from, indicating a uniformly high level of resistant alleles. The loss of efficacy of the Nix formulation (Prestige Brand, Tarrytown, NY) from 1998 to 2013 was correlated to the increase in kdr-type mutations. These data provide a plausible reason for the decrease in the effectiveness of permethrin in the Nix formulation, which is the parallel increase of kdr-type mutations in lice over time. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America.

Cloud Climatology for Land Stations Worldwide, 1971-2009 (NDP-026D)

DOE Data Explorer

Hahn, C. J. [University of Arizona; Warren, S. G. [University of Washington; Eastman, R. [University of Washington

2012-08-01

Surface synoptic weather reports for 39 years have been processed to provide a climatology of clouds for each of over 5000 land-based weather stations with long periods of record both day and night. For each station, this digital archive includes: multi-year annual, seasonal and monthly averages for day and night separately; seasonal and monthly averages by year; averages for eight times per day; and analyses of the first harmonic for the annual and diurnal cycles. Averages are given for total cloud cover, clear-sky frequency, and 9 cloud types: 5 in the low level (fog, St, Sc, Cu, Cb), 3 in the middle level (Ns, As, Ac) and one in the high level (all cirriform clouds combined). Cloud amounts and frequencies of occurrence are given for all types. In addition, non-overlapped amounts are given for middle and high cloud types, and average base heights are given for low cloud types. Nighttime averages were obtained by using only those reports that met an "illuminance criterion" (i.e., made under adequate moonlight or twilight), thus making possible the determination of diurnal cycles and nighttime trends for cloud types.The authors have also produced an online, gridded atlas of the cloud observations contained in NDP-026D. The Online Cloud Atlas containing NDP-026D data is available via the University of Washington.

SNR enhancement for downhole microseismic data based on scale classification shearlet transform

NASA Astrophysics Data System (ADS)

Li, Juan; Ji, Shuo; Li, Yue; Qian, Zhihong; Lu, Weili

2018-06-01

Shearlet transform (ST) can be effective in 2D signal processing, due to its parabolic scaling, high directional sensitivity, and optimal sparsity. ST combined with thresholding has been successfully applied to suppress random noise. However, because of the low magnitude and high frequency of a downhole microseismic signal, the coefficient values of valid signals and noise are similar in the shearlet domain. As a result, it is difficult to use for denoising. In this paper, we present a scale classification ST to solve this problem. The ST is used to decompose noisy microseismic data into serval scales. By analyzing the spectrum and energy distribution of the shearlet coefficients of microseismic data, we divide the scales into two types: low-frequency scales which contain less useful signal and high-frequency scales which contain more useful signal. After classification, we use two different methods to deal with the coefficients on different scales. For the low-frequency scales, the noise is attenuated using a thresholding method. As for the high-frequency scales, we propose to use a generalized Gauss distribution model based a non-local means filter, which takes advantage of the temporal and spatial similarity of microseismic data. The experimental results on both synthetic records and field data illustrate that our proposed method preserves the useful components and attenuates the noise well.

Low-cost FM oscillator for capacitance type of blade tip clearance measurement system

NASA Technical Reports Server (NTRS)

Barranger, John P.

1987-01-01

The frequency-modulated (FM) oscillator described is part of a blade tip clearance measurement system that meets the needs of a wide class of fans, compressors, and turbines. As a result of advancements in the technology of ultra-high-frequency operational amplifiers, the FM oscillator requires only a single low-cost integrated circuit. Its carrier frequency is 42.8 MHz when it is used with an integrated probe and connecting cable assembly consisting of a 0.81 cm diameter engine-mounted capacitance probe and a 61 cm long hermetically sealed coaxial cable. A complete circuit analysis is given, including amplifier negative resistance characteristics. An error analysis of environmentally induced effects is also derived, and an error-correcting technique is proposed. The oscillator can be calibrated in the static mode and has a negative peak frequency deviation of 400 kHz for a rotor blade thickness of 1.2 mm. High-temperature performance tests of the probe and 13 cm of the adjacent cable show good accuracy up to 600 C, the maximum permissible seal temperature. The major source of error is the residual FM oscillator noise, which produces a clearance error of + or - 10 microns at a clearance of 0.5 mm. The oscillator electronics accommodates the high rotor speeds associated with small engines, the signals from which may have frequency components as high as 1 MHz.

Micromachined High Frequency PMN-PT/Epoxy 1-3 Composite Ultrasonic Annular Array

PubMed Central

Liu, Changgeng; Djuth, Frank; Li, Xiang; Chen, Ruimin; Zhou, Qifa; Shung, K. Kirk

2013-01-01

This paper reports the design, fabrication, and performance of miniature micromachined high frequency PMN-PT/epoxy 1-3 composite ultrasonic annular arrays. The PMN-PT single crystal 1-3 composites were made with micromachining techniques. The area of a single crystal pillar was 9 μm × 9 μm. The width of the kerf among pillars was ~ 5 μm and the kerfs were filled with a polymer. The composite thickness was 25 μm. A six-element annular transducer of equal element area of 0.2 mm2 with 16 μm kerf widths between annuli was produced. The aperture size the array transducer is about 1.5 mm in diameter. A novel electrical interconnection strategy for high density array elements was implemented. After the transducer was attached to the electric connection board and packaged, the array transducer was tested in a pulse/echo arrangement, whereby the center frequency, bandwidth, two-way insertion loss (IL), and cross talk between adjacent elements were measured for each annulus. The center frequency was 50 MHz and -6 dB bandwidth was 90%. The average insertion loss was 19.5 dB at 50 MHz and the crosstalk between adjacent elements was about -35 dB. The micromachining techniques described in this paper are promising for the fabrication of other types of high frequency transducers e.g. 1D and 2D arrays. PMID:22119324

[Analysis on occupational noise-induced hearing loss of different type workers in underground mining].

PubMed

Liu, Q C; Duo, C H; Wang, Z; Yan, K; Zhang, J; Xiong, W; Zhu, M

2017-11-20

Objective: To investigate hearing loss status of blasters, drillers mechanics and so on in underground mining, and put forward suggestion diagnosis of occupational explosive deafness and occupational deafness. Methods: Underground excavation workers in a metal mine were recruited in this study, those with a history of ear disease and non-occupational deafness were all excluded. Finally, the features of pure tone audiometry of 459 noise-exposed workers were analyzed. Results: High-frequency hearing loss occurred on 351workers and the positive detection rate was 74.29%, workers who had both high-frequency and linguistic frequency hearing loss were 51 and the positive detection rate was 11.11%. The positive detection of high-frequency hearing loss in right ear (χ(2)=9.427 and P = 0.024) and in left ear (χ(2)=14.375, P =0.002) was significantly different between different exposure age groups. The positive detection of high-frequency hearing loss of driving group was the highest, followed by blasting group, mining group and machine repair group. The characteristics of the hearing loss caused by drilling noise of the blasting workers with no accident occurred were in line with that of noise-induced hearing loss. Conclusion: The diagnosis grading should be carried out according to the diagnostic criteria of occupational noise-induced deafness for the employees who engaged in the blasting operation with no record of blast accident.

Spectral analysis and filtering techniques in digital spatial data processing

USGS Publications Warehouse

Pan, Jeng-Jong

1989-01-01

A filter toolbox has been developed at the EROS Data Center, US Geological Survey, for retrieving or removing specified frequency information from two-dimensional digital spatial data. This filter toolbox provides capabilities to compute the power spectrum of a given data and to design various filters in the frequency domain. Three types of filters are available in the toolbox: point filter, line filter, and area filter. Both the point and line filters employ Gaussian-type notch filters, and the area filter includes the capabilities to perform high-pass, band-pass, low-pass, and wedge filtering techniques. These filters are applied for analyzing satellite multispectral scanner data, airborne visible and infrared imaging spectrometer (AVIRIS) data, gravity data, and the digital elevation models (DEM) data. -from Author

Inducing somatic meiosis-like reduction at high frequency by caffeine in root-tip cells of Vicia faba.

PubMed

Chen, Y; Zhang, L; Zhou, Y; Geng, Y; Chen, Z

2000-07-20

Germinated seeds of Vicia faba were treated in caffeine solutions of different concentration for different durations to establish the inducing system of somatic meiosis-like reduction. The highest frequency of somatic meiosis-like reduction could reach up to 54.0% by treating the root tips in 70 mmol/l caffeine solution for 2 h and restoring for 24 h. Two types of somatic meiosis-like reduction were observed. One was reductional grouping, in which the chromosomes in a cell usually separated into two groups, and the role of spindle fibers did not show. The other type was somatic meiosis, which was analogous to meiosis presenting in gametogenesis, and chromosome pairing and chiasmata were visualized.

Note: A kinematic shaker system for high amplitude, low frequency vibration testing

NASA Astrophysics Data System (ADS)

Swaminathan, Anand; Poese, Matthew E.; Smith, Robert W. M.; Garrett, Steven L.

2015-11-01

This note describes a shaker system capable of high peak-velocity, large amplitude, low frequency, near-sinusoidal excitation that has been constructed and employed in experiments on the inhibition of Rayleigh-Bénard convection using acceleration modulation. The production of high peak-velocity vibration is of interest in parametric excitation problems of this type and reaches beyond the capabilities of standard electromagnetic shakers. The shaker system described employs a kinematic linkage to two counter-rotating flywheels, driven by a variable-speed electrical motor, producing peak-to-peak displacements of 15.24 cm to a platform mounted on two guide rails. In operation, this shaker has been demonstrated to produce peak speeds of up to 3.7 m/s without failure.

Different dynamic resting state fMRI patterns are linked to different frequencies of neural activity

PubMed Central

Thompson, Garth John; Pan, Wen-Ju

2015-01-01

Resting state functional magnetic resonance imaging (rsfMRI) results have indicated that network mapping can contribute to understanding behavior and disease, but it has been difficult to translate the maps created with rsfMRI to neuroelectrical states in the brain. Recently, dynamic analyses have revealed multiple patterns in the rsfMRI signal that are strongly associated with particular bands of neural activity. To further investigate these findings, simultaneously recorded invasive electrophysiology and rsfMRI from rats were used to examine two types of electrical activity (directly measured low-frequency/infraslow activity and band-limited power of higher frequencies) and two types of dynamic rsfMRI (quasi-periodic patterns or QPP, and sliding window correlation or SWC). The relationship between neural activity and dynamic rsfMRI was tested under three anesthetic states in rats: dexmedetomidine and high and low doses of isoflurane. Under dexmedetomidine, the lightest anesthetic, infraslow electrophysiology correlated with QPP but not SWC, whereas band-limited power in higher frequencies correlated with SWC but not QPP. Results were similar under isoflurane; however, the QPP was also correlated to band-limited power, possibly due to the burst-suppression state induced by the anesthetic agent. The results provide additional support for the hypothesis that the two types of dynamic rsfMRI are linked to different frequencies of neural activity, but isoflurane anesthesia may make this relationship more complicated. Understanding which neural frequency bands appear as particular dynamic patterns in rsfMRI may ultimately help isolate components of the rsfMRI signal that are of interest to disorders such as schizophrenia and attention deficit disorder. PMID:26041826

Typical Geo-Hazards and Countermeasures of Mines in Yunnan Province, Southwest China

NASA Astrophysics Data System (ADS)

Cheng, Xianfeng; Qi, Wufu; Huang, Qianrui; Zhao, Xueqiong; Fang, Rong; Xu, Jun

2016-10-01

Mining-induced geo-hazards have caused enormous destruction and threat to mines. Known as the "kingdom of nonferrous metals" and located in Southwest China, Yunnan Province developed mining-induced geo-hazards well with characteristics of multiple types, widespread distribution and serious damage. Landslides and debris flows are two common sub-types of geohazards causing most serious damage in Yunnan, and some of them were very representative in the world. Two landslides and two debris flows were chosen to analyze deeply. Both Laojinshan Landslide and Sunjiaqing Landslide possess the characteristic of rock avalanches. The high sliding speed and long distance made the landslides translate into clastic flows with impact force and caused enormous destruction. Rainstorm and mining waste rock were two main factors to induce debris flows in Yunnan mines. Heishan valley debris flow of Dongchuan copper mine was a super large rainstorm type viscose debris flow with very low frequency, which brought a good caution to utilize valleys which looked an unlikely debris flow. Nandagou Valley of Jinding lead-zinc mine in Lanping County was a rainstorm stimulating, gully-type, high frequency and large scale debris flow, which was induced by mining activities. Many countermeasures have been used for Yunnan mines, including engineering treatment technology and ecological remediation, monitoring and forecasting, relocation and public administration.

Automatic recognition of coronal type II radio bursts: The ARBIS 2 method and first observations

NASA Astrophysics Data System (ADS)

Lobzin, Vasili; Cairns, Iver; Robinson, Peter; Steward, Graham; Patterson, Garth

Major space weather events such as solar flares and coronal mass ejections are usually accompa-nied by solar radio bursts, which can potentially be used for real-time space weather forecasts. Type II radio bursts are produced near the local plasma frequency and its harmonic by fast electrons accelerated by a shock wave moving through the corona and solar wind with a typi-cal speed of 1000 km s-1 . The coronal bursts have dynamic spectra with frequency gradually falling with time and durations of several minutes. We present a new method developed to de-tect type II coronal radio bursts automatically and describe its implementation in an extended Automated Radio Burst Identification System (ARBIS 2). Preliminary tests of the method with spectra obtained in 2002 show that the performance of the current implementation is quite high, ˜ 80%, while the probability of false positives is reasonably low, with one false positive per 100-200 hr for high solar activity and less than one false event per 10000 hr for low solar activity periods. The first automatically detected coronal type II radio bursts are also presented. ARBIS 2 is now operational with IPS Radio and Space Services, providing email alerts and event lists internationally.

Red laser based on intra-cavity Nd:YAG/CH4 frequency doubled Raman lasers

NASA Astrophysics Data System (ADS)

Wang, Yanchao; Wang, Pengyuan; Liu, Jinbo; Liu, Wanfa; Guo, Jingwei

2017-01-01

Stimulated Raman scattering (SRS) is a powerful tool for the extension of the spectral range of lasers. To obtain efficient Raman conversion in SRS, many researchers have studied different types of Raman laser configurations. Among these configurations, the intra-cavity type is particularly attractive. Intra-cavity SRS has the advantages of high intra-cavity laser intensity, low-SRS threshold, and high Raman conversion efficiency. In this paper, An Q-switched intra-cavity Nd: YAG/CH4 frequency-doubled Raman lasers is reported. A negative branch confocal resonator with M= 1.25 is used for the frequency-doubling of Nd: YAG laser. The consequent 532nm light is confined in intra- cavity SRS with travelling wave resonator, and the focal of one mirror of cavity is overlap with the center of the other mirror of the cavity. We found this design is especially efficient to reduce the threshold of SRS, and increase conversion efficiency. The threshold is measured to be 0.62 MW, and at the pump energy of 16.1 mJ, the conversion efficiency is 34%. With the smaller magnification M, the threshold could further decrease, and the conversion efficiency could be improved further. This is a successful try to extend the spectral range of a laser to the shorter wavelength by SRS, and this design may play an important role in the fulfillment of high power red lasers.

Distributed feedback guided surface acoustic wave microresonator

NASA Astrophysics Data System (ADS)

Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.

1989-08-01

Surface acoustic wave resonators have been used in a number of applications: high-Q frequency filtering, very accurate frequency sources, etc. A major disadvantage of conventional resonators is their large dimensions, which makes them inadequate for integrated acoustics applications. In order to overcome these size limitations a new type of microresonator was designed, developed, and tested. In this paper, theoretical calculations and measurements on two kinds of such devices (a corrugated waveguide filter and a microresonator structure) are presented and their possible applications are discussed.

Zero energy-storage ballast for compact fluorescent lamps

DOEpatents

Schultz, W.N.; Thomas, R.J.

1999-08-31

A CFL ballast includes complementary-type switching devices connected in series with their gates connected together at a control node. The switching devices supply a resonant tank circuit which is tuned to a frequency near, but slightly lower than, the resonant frequency of a resonant control circuit. As a result, the tank circuit restarts oscillations immediately following each zero crossing of the bus voltage. Such rapid restarts avoid undesirable flickering while maintaining the operational advantages and high efficacy of the CFL ballast. 4 figs.

Zero energy-storage ballast for compact fluorescent lamps

DOEpatents

Schultz, William Newell; Thomas, Robert James

1999-01-01

A CFL ballast includes complementary-type switching devices connected in series with their gates connected together at a control node. The switching devices supply a resonant tank circuit which is tuned to a frequency near, but slightly lower than, the resonant frequency of a resonant control circuit. As a result, the tank circuit restarts oscillations immediately following each zero crossing of the bus voltage. Such rapid restarts avoid undesirable flickering while maintaining the operational advantages and high efficacy of the CFL ballast.

PERSONAL RADIATION MONITOR

DOEpatents

Dilworth, R.H.; Borkowski, C.J.

1961-12-26

A transistorized, fountain pen type radiation monitor to be worn on the person is described. Radiation produces both light flashes in a small bulb and an audible warning tone, the frequency of both the tone and light flashes being proportional to radiation intensity. The device is powered by a battery and a blocking oscillator step-up power supply The oscillator frequency- is regulated to be proportional to the radiation intensity, to provide adequate power in high radiation fields, yet minimize battery drain at low operating intensities. (AEC)

Novel missense mutations in MYO7A underlying postlingual high- or low-frequency non-syndromic hearing impairment in two large families from China.

PubMed

Sun, Yi; Chen, Jing; Sun, Hanjun; Cheng, Jing; Li, Jianzhong; Lu, Yu; Lu, Yanping; Jin, Zhanguo; Zhu, Yuhua; Ouyang, Xiaomei; Yan, Denise; Dai, Pu; Han, Dongyi; Yang, Weiyan; Wang, Rongguang; Liu, Xuezhong; Yuan, Huijun

2011-01-01

The myosin VIIA (MYO7A) gene encodes a protein classified as an unconventional myosin. Mutations within MYO7A can lead to both syndromic and non-syndromic hearing impairment in humans. Among different mutations reported in MYO7A, only five led to non-syndromic sensorineural deafness autosomal dominant type 11 (DFNA11). Here, we present the clinical, genetic and molecular characteristics of two large Chinese DFNA11 families with either high- or low-frequency hearing loss. Affected individuals of family DX-J033 have a sloping audiogram at young ages with high frequency are most affected. With increasing age, all test frequencies are affected. Affected members of family HB-S037 present with an ascending audiogram affecting low frequencies at young ages, and then all frequencies are involved with increasing age. Genome-wide linkage analysis mapped the disease loci within the DFNA11 interval in both families. DNA sequencing of MYO7A revealed two novel nucleotide variations, c.652G > A (p.D218N) and c.2011G > A (p.G671S), in the two families. It is for the first time that the mutations identified in MYO7A in the present study are being implicated in DFNA11 in a Chinese population. For the first time, we tested electrocochleography (ECochG) in a DFNA11 family with low-frequency hearing loss. We speculate that the low-frequency sensorineural hearing loss in this DFNA11 family was not associated with endolymphatic hydrops.

Risks and injuries in laser and high-frequency applications

NASA Astrophysics Data System (ADS)

Giering, K.; Philipp, Carsten M.; Berlien, Hans-Peter

1995-01-01

An analysis of injuries and risks using high frequency (HF) and lasers in medicine based on a literature search with MEDLINE was performed. The cases reported in the literature were classified according to the following criteria: (1) Avoidable in an optimal operational procedure. These kind of injuries are caused by a chain of unfortunate incidents. They are in principle avoidable by the 'right action at the right time' which presupposes an appropriate training of the operating team, selection of the optimal parameters for procedure and consideration of all safety instructions. (2) Avoidable, caused by malfunction of the equipment and/or accessories. The injuries classified into this group are avoidable if all safety regulations were fulfilled. This includes a pre-operational check-up and the use of medical lasers and high frequency devices only which meet the international safety standards. (3) Avoidable, caused by misuse/mistake. Injuries of this group were caused by an inappropriate selection of the procedure, wrong medical indication or mistakes during application. (4) Unavoidable, fateful. These injuries can be caused by risks inherent to the type of energy used, malfunction of the equipment and/or accessories though a pre-operational check-up was done. Some risks and complications are common to high frequency and laser application. But whereas these risks can be excluded easily in laser surgery there is often a great expenditure necessary or they are not avoidable if high frequency if used. No unavoidable risks due to laser energy occur.

Black Phosphorus Flexible Thin Film Transistors at Gighertz Frequencies.

PubMed

Zhu, Weinan; Park, Saungeun; Yogeesh, Maruthi N; McNicholas, Kyle M; Bank, Seth R; Akinwande, Deji

2016-04-13

Black phosphorus (BP) has attracted rapidly growing attention for high speed and low power nanoelectronics owing to its compelling combination of tunable bandgap (0.3 to 2 eV) and high carrier mobility (up to ∼1000 cm(2)/V·s) at room temperature. In this work, we report the first radio frequency (RF) flexible top-gated (TG) BP thin-film transistors on highly bendable polyimide substrate for GHz nanoelectronic applications. Enhanced p-type charge transport with low-field mobility ∼233 cm(2)/V·s and current density of ∼100 μA/μm at VDS = -2 V were obtained from flexible BP transistor at a channel length L = 0.5 μm. Importantly, with optimized dielectric coating for air-stability during microfabrication, flexible BP RF transistors afforded intrinsic maximum oscillation frequency fMAX ∼ 14.5 GHz and unity current gain cutoff frequency fT ∼ 17.5 GHz at a channel length of 0.5 μm. Notably, the experimental fT achieved here is at least 45% higher than prior results on rigid substrate, which is attributed to the improved air-stability of fabricated BP devices. In addition, the high-frequency performance was investigated through mechanical bending test up to ∼1.5% tensile strain, which is ultimately limited by the inorganic dielectric film rather than the 2D material. Comparison of BP RF devices to other 2D semiconductors clearly indicates that BP offers the highest saturation velocity, an important metric for high-speed and RF flexible nanosystems.

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.

Nonlinear acoustic spectroscopy of cracked flaws and disbonds: Fundamentals, techniques, and applications

NASA Astrophysics Data System (ADS)

Maev, R. Gr.; Solodov, I. Yu.

2000-05-01

Classical nonlinear acoustics of solids operates with distributed material nonlinearity related to unharmonicity of molecular interaction forces. Weakening of molecular bonds in a defect area or intermittent lack of elastic coupling between the faces of a vibrating crack or unbond ("clapping") results in anomalously high local contact acoustic nonlinearity (CAN). CAN properties and spectral features are different from those of the classical analog and important to develop new acoustic NDE techniques. Three approaches to nonlinear NDE methodology have been experimentally verified: low-frequency (hundreds of Hz) vibration technique, intermediate-frequency (hundreds of kHz) standing wave and high-frequency (tens of MHz) propagation modes. Low-frequency nonlinear contact vibrations revealed multiple sub- and super-harmonics generation featuring non-monotonous (sinx/x type) spectra. Parametric instability observed in resonator with a nonlinear contact leads to the output spectrum splitting up into successive sub-harmonics as the wave amplitude increases. High-frequency experiments demonstrated abnormal increases in the third harmonic amplitude: 3 or 4 order enhancement of the 3-ω nonlinear parameter was measured for the nonlinear contact. The CAN spectral features in both acoustic and vibration modes were used for nonlinear NDE of simulated and realistic flaws in glass, metal welds, etc. The sensitivities of the techniques are compared and their practical applicability assessed.

Performance of High-frequency High-flux Magnetic Cores at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Gerber, Scott S.; Hammoud, Ahmad; Elbuluk, Malik E.; Patterson, Richard L.

2002-01-01

Three magnetic powder cores and one ferrite core, which are commonly used in inductor and transformer design for switch mode power supplies, were selected for investigation at cryogenic temperatures. The powder cores are Molypermalloy Core (MPC), High Flux Core (HFC), and Kool Mu Core (KMC). The performance of four inductors utilizing these cores has been evaluated as a function of temperature from 20 C to -180 C. All cores were wound with the same wire type and gauge to obtain equal values of inductance at room temperature. Each inductor was evaluated in terms of its inductance, quality (Q) factor, resistance, and dynamic hysteresis characteristics (B-H loop) as a function of temperature and frequency. Both sinusoidal and square wave excitations were used in these investigations. Measured data obtained on the inductance showed that both the MPC and the HFC cores maintain a constant inductance value, whereas with the KMC and ferrite core hold a steady value in inductance with frequency but decrease as temperature is decreased. All cores exhibited dependency, with varying degrees, in their quality factor and resistance on test frequency and temperature. Except for the ferrite, all cores exhibited good stability in the investigated properties with temperature as well as frequency. Details of the experimental procedures and test results are presented and discussed in the paper.

Examining the Affordances of Dual Cognitive Processing to Explain the Development of High School Students' Nature of Science Views

NASA Astrophysics Data System (ADS)

Jackson, Luke M.

This mixed method study was aimed at examining the influence of dual processing (Type 1 and Type 2 thinking) on the development of high school students' nature of science (NOS) views. Type 1 thinking is intuitive, experiential, and heuristic. Type 2 thinking is rational, analytical, and explicit. Three research questions were asked: (1) Do the experiential process (Type 1) and the logical process (Type 2) influence the development of students' NOS views? (2) If there is an influence on students' NOS views, then what is the nature of relationship between the experiential process (Type 1) and the development of NOS views? (3) What is the nature of relationship between the logical process (Type 2) and the development of NOS views? The Views of Nature of Science Questionnaire C (VNOS-C; Lederman, Abd-El-Khalick, Bell, & Schwartz, 2002) was administered to 29 high school students at the beginning and at the end of an explicit-reflective NOS intervention offered in an Advanced Placement environmental science course. Changes in students' NOS views were calculated through a chi-square test and examining the percentage of students holding NOS views at various levels of sophistication. With the chi-square goodness of fit test performed, the relationship between pre and post NOS scores was not significant, X2(3, 29) = 4.78, p <.05. The informed and preinformed NOS views increased (14%, 17%) in frequency while the mixed and uninformed NOS views decreased (i.e. improved 26%, 24%) in frequency from pre to posttest. The reading discussions were coded based on the EBR framework (Furtak et al., 2010) to analyze the use of dual processing. Type1 and Type 2 thinking were both used during the intervention and reading reflections. Type 2 thinking was more prominent when analyzing a problem, formulating a hypothesis, or stating logical claims. The association of NOS education and Type 1 and Type 2 thinking in scientific literacy was examined, and implications and future research are discussed.

Type 2 diabetes mellitus: distribution of genetic markers in Kazakh population.

PubMed

Sikhayeva, Nurgul; Talzhanov, Yerkebulan; Iskakova, Aisha; Dzharmukhanov, Jarkyn; Nugmanova, Raushan; Zholdybaeva, Elena; Ramanculov, Erlan

2018-01-01

Ethnic differences exist in the frequencies of genetic variations that contribute to the risk of common disease. This study aimed to analyse the distribution of several genes, previously associated with susceptibility to type 2 diabetes and obesity-related phenotypes, in a Kazakh population. A total of 966 individuals belonging to the Kazakh ethnicity were recruited from an outpatient clinic. We genotyped 41 common single nucleotide polymorphisms (SNPs) previously associated with type 2 diabetes in other ethnic groups and 31 of these were in Hardy-Weinberg equilibrium. The obtained allele frequencies were further compared to publicly available data from other ethnic populations. Allele frequencies for other (compared) populations were pooled from the haplotype map (HapMap) database. Principal component analysis (PCA), cluster analysis, and multidimensional scaling (MDS) were used for the analysis of genetic relationship between the populations. Comparative analysis of allele frequencies of the studied SNPs showed significant differentiation among the studied populations. The Kazakh population was grouped with Asian populations according to the cluster analysis and with the Caucasian populations according to PCA. According to MDS, results of the current study show that the Kazakh population holds an intermediate position between Caucasian and Asian populations. A high percentage of population differentiation was observed between Kazakh and world populations. The Kazakh population was clustered with Caucasian populations, and this result may indicate a significant Caucasian component in the Kazakh gene pool.

Pornography use and sexual aggression: the impact of frequency and type of pornography use on recidivism among sexual offenders.

PubMed

Kingston, Drew A; Fedoroff, Paul; Firestone, Philip; Curry, Susan; Bradford, John M

2008-01-01

In this study, we examined the unique contribution of pornography consumption to the longitudinal prediction of criminal recidivism in a sample of 341 child molesters. We specifically tested the hypothesis, based on predictions informed by the confluence model of sexual aggression that pornography will be a risk factor for recidivism only for those individuals classified as relatively high risk for re-offending. Pornography use (frequency and type) was assessed through self-report and recidivism was measured using data from a national database from the Royal Canadian Mounted Police. Indices of recidivism, which were assessed up to 15 years after release, included an overall criminal recidivism index, as well as subcategories focusing on violent (including sexual) recidivism and sexual recidivism alone. Results for both frequency and type of pornography use were generally consistent with our predictions. Most importantly, after controlling for general and specific risk factors for sexual aggression, pornography added significantly to the prediction of recidivism. Statistical interactions indicated that frequency of pornography use was primarily a risk factor for higher-risk offenders, when compared with lower-risk offenders, and that content of pornography (i.e., pornography containing deviant content) was a risk factor for all groups. The importance of conceptualizing particular risk factors (e.g., pornography), within the context of other individual characteristics is discussed.

Media exposure and oral health outcomes among adults.

PubMed

Zini, Avraham; Sgan-Cohen, Harold D; Vered, Yuval

2013-02-01

To assess the impact of media exposure on oral health outcomes among Jewish adults in Jerusalem, Israel, by means of a conceptual hierarchical model. A cross-sectional study was conducted using a stratified sample of 254 adults 35 to 44 years (mean age, 38.63 years) in Jerusalem, Israel. Media exposure was operationally categorized by type and frequency. Behavioral data included toothbrushing, dental attendance, oral hygiene aids use, plaque level, sugar consumption, and smoking. Clinical outcomes were assessed according to the decayed/missing/filled teeth (DMFT) index and the community periodontal index (CPI). Results were analyzed by chi-square test, independent test, one-way ANOVA, and linear and multiple logistic regression models. A total of 254 examinees consisted of 127 men and 127 mean (married couples). High type and high frequency of media exposure, as compared with other modes, revealed statistically significant higher caries experience (DMFT, 13.10), higher level of untreated decay (D, 1.67), and lower periodontal health (CPI [0], 0.39). A conceptual hierarchical regression model identified that the relationship described was mediated by sociodemographic determinants (education) and behavioral determinants (dental attendance and plaque level). Media exposure should be observed by community health program planners and general practitioners to examine the type and frequency of the messages. They also need to react on time to balanced bad advertising and add a good message at the community. This pragmatic approach could lead to better use of the media and improve oral health behavior and outcomes.

High Frequency Cut-off Characteristics of Strong Ground Motion Records at Hard Sites, Subduction and Intra-Slab Earthquakes

NASA Astrophysics Data System (ADS)

Kagawa, T.; Tsurugi, M.; Irikura, K.

2006-12-01

A study on high frequency cut-off characteristics of strong ground motion is presented for subduction and intra- slab earthquakes in Japan. In the latest decade, observed records at hard sites are published by NIED, National Research Institute for Earth Science and Disaster Prevention, and JCOLD, Japan Commission on Large Dams. Especially, KiK-net and K-NET maintained by NIED have been providing high quality data to study high-frequency characteristics. Kagawa et al.(2003) studied the characteristics for crustal earthquakes. We apply the same methodology to the recently observed Japanese records due to subduction and intra-slab earthquakes. We assume a Butterworth type high-cut filter with limit frequency (fmax) and its power factor. These two parameters were derived from Fourier spectrum of observed records fitting the theoretical filter shape. After analyzing the result from view points of site, path, or source effects, an averaged filter model is proposed with its standard deviation. Kagawa et al.(2003) derived average as 8.3 Hz with power factor of 1.92. It is used for strong ground motion simulation. We will propose parameters for the high-cut filters of subduction and intra-slab earthquakes and compare them with the results by Kagawa et al.(2003). REFERENCES: Kagawa et al. (2003), 27JEES (in Japanese with English Abstract).

Effect of gravity opientation on the thermal performance of Stirling-type pulse tube cryocoolers

NASA Technical Reports Server (NTRS)

Ronald, Ross G., Jr.; Johnson, D. L.

2003-01-01

This paper extends the investigation of angular orientation effects to the refrigeration performance of high frequency (-40 Hz) Stirling-type pulse tube cryocoolers typical of those used in long-life space applications. Strong orientation effects on the performance of such cryocoolers have recently been observed during system-level testing of both linear and U-tube type pulse tubes. To quantify the angular dependency effects, data have been gathered on both U-tube and linear type pulse tubes of two different manufacturers as a function of orientation angle, cold-tip temperature, and compressor stroke.

Sequence data and association statistics from 12,940 type 2 diabetes cases and controls.

PubMed

Flannick, Jason; Fuchsberger, Christian; Mahajan, Anubha; Teslovich, Tanya M; Agarwala, Vineeta; Gaulton, Kyle J; Caulkins, Lizz; Koesterer, Ryan; Ma, Clement; Moutsianas, Loukas; McCarthy, Davis J; Rivas, Manuel A; Perry, John R B; Sim, Xueling; Blackwell, Thomas W; Robertson, Neil R; Rayner, N William; Cingolani, Pablo; Locke, Adam E; Tajes, Juan Fernandez; Highland, Heather M; Dupuis, Josee; Chines, Peter S; Lindgren, Cecilia M; Hartl, Christopher; Jackson, Anne U; Chen, Han; Huyghe, Jeroen R; van de Bunt, Martijn; Pearson, Richard D; Kumar, Ashish; Müller-Nurasyid, Martina; Grarup, Niels; Stringham, Heather M; Gamazon, Eric R; Lee, Jaehoon; Chen, Yuhui; Scott, Robert A; Below, Jennifer E; Chen, Peng; Huang, Jinyan; Go, Min Jin; Stitzel, Michael L; Pasko, Dorota; Parker, Stephen C J; Varga, Tibor V; Green, Todd; Beer, Nicola L; Day-Williams, Aaron G; Ferreira, Teresa; Fingerlin, Tasha; Horikoshi, Momoko; Hu, Cheng; Huh, Iksoo; Ikram, Mohammad Kamran; Kim, Bong-Jo; Kim, Yongkang; Kim, Young Jin; Kwon, Min-Seok; Lee, Juyoung; Lee, Selyeong; Lin, Keng-Han; Maxwell, Taylor J; Nagai, Yoshihiko; Wang, Xu; Welch, Ryan P; Yoon, Joon; Zhang, Weihua; Barzilai, Nir; Voight, Benjamin F; Han, Bok-Ghee; Jenkinson, Christopher P; Kuulasmaa, Teemu; Kuusisto, Johanna; Manning, Alisa; Ng, Maggie C Y; Palmer, Nicholette D; Balkau, Beverley; Stančáková, Alena; Abboud, Hanna E; Boeing, Heiner; Giedraitis, Vilmantas; Prabhakaran, Dorairaj; Gottesman, Omri; Scott, James; Carey, Jason; Kwan, Phoenix; Grant, George; Smith, Joshua D; Neale, Benjamin M; Purcell, Shaun; Butterworth, Adam S; Howson, Joanna M M; Lee, Heung Man; Lu, Yingchang; Kwak, Soo-Heon; Zhao, Wei; Danesh, John; Lam, Vincent K L; Park, Kyong Soo; Saleheen, Danish; So, Wing Yee; Tam, Claudia H T; Afzal, Uzma; Aguilar, David; Arya, Rector; Aung, Tin; Chan, Edmund; Navarro, Carmen; Cheng, Ching-Yu; Palli, Domenico; Correa, Adolfo; Curran, Joanne E; Rybin, Dennis; Farook, Vidya S; Fowler, Sharon P; Freedman, Barry I; Griswold, Michael; Hale, Daniel Esten; Hicks, Pamela J; Khor, Chiea-Chuen; Kumar, Satish; Lehne, Benjamin; Thuillier, Dorothée; Lim, Wei Yen; Liu, Jianjun; Loh, Marie; Musani, Solomon K; Puppala, Sobha; Scott, William R; Yengo, Loïc; Tan, Sian-Tsung; Taylor, Herman A; Thameem, Farook; Wilson, Gregory; Wong, Tien Yin; Njølstad, Pål Rasmus; Levy, Jonathan C; Mangino, Massimo; Bonnycastle, Lori L; Schwarzmayr, Thomas; Fadista, João; Surdulescu, Gabriela L; Herder, Christian; Groves, Christopher J; Wieland, Thomas; Bork-Jensen, Jette; Brandslund, Ivan; Christensen, Cramer; Koistinen, Heikki A; Doney, Alex S F; Kinnunen, Leena; Esko, Tõnu; Farmer, Andrew J; Hakaste, Liisa; Hodgkiss, Dylan; Kravic, Jasmina; Lyssenko, Valeri; Hollensted, Mette; Jørgensen, Marit E; Jørgensen, Torben; Ladenvall, Claes; Justesen, Johanne Marie; Käräjämäki, Annemari; Kriebel, Jennifer; Rathmann, Wolfgang; Lannfelt, Lars; Lauritzen, Torsten; Narisu, Narisu; Linneberg, Allan; Melander, Olle; Milani, Lili; Neville, Matt; Orho-Melander, Marju; Qi, Lu; Qi, Qibin; Roden, Michael; Rolandsson, Olov; Swift, Amy; Rosengren, Anders H; Stirrups, Kathleen; Wood, Andrew R; Mihailov, Evelin; Blancher, Christine; Carneiro, Mauricio O; Maguire, Jared; Poplin, Ryan; Shakir, Khalid; Fennell, Timothy; DePristo, Mark; de Angelis, Martin Hrabé; Deloukas, Panos; Gjesing, Anette P; Jun, Goo; Nilsson, Peter; Murphy, Jacquelyn; Onofrio, Robert; Thorand, Barbara; Hansen, Torben; Meisinger, Christa; Hu, Frank B; Isomaa, Bo; Karpe, Fredrik; Liang, Liming; Peters, Annette; Huth, Cornelia; O'Rahilly, Stephen P; Palmer, Colin N A; Pedersen, Oluf; Rauramaa, Rainer; Tuomilehto, Jaakko; Salomaa, Veikko; Watanabe, Richard M; Syvänen, Ann-Christine; Bergman, Richard N; Bharadwaj, Dwaipayan; Bottinger, Erwin P; Cho, Yoon Shin; Chandak, Giriraj R; Chan, Juliana Cn; Chia, Kee Seng; Daly, Mark J; Ebrahim, Shah B; Langenberg, Claudia; Elliott, Paul; Jablonski, Kathleen A; Lehman, Donna M; Jia, Weiping; Ma, Ronald C W; Pollin, Toni I; Sandhu, Manjinder; Tandon, Nikhil; Froguel, Philippe; Barroso, Inês; Teo, Yik Ying; Zeggini, Eleftheria; Loos, Ruth J F; Small, Kerrin S; Ried, Janina S; DeFronzo, Ralph A; Grallert, Harald; Glaser, Benjamin; Metspalu, Andres; Wareham, Nicholas J; Walker, Mark; Banks, Eric; Gieger, Christian; Ingelsson, Erik; Im, Hae Kyung; Illig, Thomas; Franks, Paul W; Buck, Gemma; Trakalo, Joseph; Buck, David; Prokopenko, Inga; Mägi, Reedik; Lind, Lars; Farjoun, Yossi; Owen, Katharine R; Gloyn, Anna L; Strauch, Konstantin; Tuomi, Tiinamaija; Kooner, Jaspal Singh; Lee, Jong-Young; Park, Taesung; Donnelly, Peter; Morris, Andrew D; Hattersley, Andrew T; Bowden, Donald W; Collins, Francis S; Atzmon, Gil; Chambers, John C; Spector, Timothy D; Laakso, Markku; Strom, Tim M; Bell, Graeme I; Blangero, John; Duggirala, Ravindranath; Tai, E Shyong; McVean, Gilean; Hanis, Craig L; Wilson, James G; Seielstad, Mark; Frayling, Timothy M; Meigs, James B; Cox, Nancy J; Sladek, Rob; Lander, Eric S; Gabriel, Stacey; Mohlke, Karen L; Meitinger, Thomas; Groop, Leif; Abecasis, Goncalo; Scott, Laura J; Morris, Andrew P; Kang, Hyun Min; Altshuler, David; Burtt, Noël P; Florez, Jose C; Boehnke, Michael; McCarthy, Mark I

2017-12-19

To investigate the genetic basis of type 2 diabetes (T2D) to high resolution, the GoT2D and T2D-GENES consortia catalogued variation from whole-genome sequencing of 2,657 European individuals and exome sequencing of 12,940 individuals of multiple ancestries. Over 27M SNPs, indels, and structural variants were identified, including 99% of low-frequency (minor allele frequency [MAF] 0.1-5%) non-coding variants in the whole-genome sequenced individuals and 99.7% of low-frequency coding variants in the whole-exome sequenced individuals. Each variant was tested for association with T2D in the sequenced individuals, and, to increase power, most were tested in larger numbers of individuals (>80% of low-frequency coding variants in ~82 K Europeans via the exome chip, and ~90% of low-frequency non-coding variants in ~44 K Europeans via genotype imputation). The variants, genotypes, and association statistics from these analyses provide the largest reference to date of human genetic information relevant to T2D, for use in activities such as T2D-focused genotype imputation, functional characterization of variants or genes, and other novel analyses to detect associations between sequence variation and T2D.

HLA-B27 antigen frequency among suspected Spondyloarthropathy patients attaining a tertiary level hospital of Bangladesh.

PubMed

Nessa, A; Tabassum, S; Sultana, S

2014-12-01

Human leukocyte antigen B27 (HLA-B27), a class I molecules of the major histocompatibility complex has a strong disease association with different types of spondarthropathies (SpA). The strength of this disease association varies markedly among racial and ethnic populations. The present study aimed to identify the HLA-B27 antigen frequencies among suspected SpA patients as well as healthy Bangladeshi individuals. The frequency of HLA-B27 was determined in 1500 patients and 1000 healthy subjects attending the Bangabandhu Sheikh Mujib Medical University (BSMMU). HLA-B 27 typing was done by microlymphocytotoxicity test using commercial kit. A total of 738 (49.2%) suspected SpA patients and 107 (10.7%) healthy subjects tested positive for HLA-B27 antigen with higher frequency among younger age groups (54.9%, 52.4% and 56.2% in 0-14 years, 15-24 years and 25-34 years of age respectively). The male female positivity was almost same (11.4% and 9.6%) among control group, but in patient group it was 53.0% and 41.2% respectively. The findings of this hospital based study showed a high frequency of HLA-B27 among suspected SpA patients with male preponderance which is comparable with neighboring countries.

Analysis of current density and specific absorption rate in biological tissue surrounding an air-core type of transcutaneous transformer for an artificial heart.

PubMed

Shiba, Kenji; Nukaya, Masayuki; Tsuji, Toshio; Koshiji, Kohji

2006-01-01

This paper reports on the specific absorption rate (SAR) and the current density analysis of biological tissue surrounding an air-core type of transcutaneous transformer for an artificial heart. The electromagnetic field in the biological tissue surrounding the transformer was analyzed by the transmission-line modeling method, and the SAR and current density as a function of frequency (200k-1 MHz) for a transcutaneous transmission of 20 W were calculated. The model's biological tissue has three layers including the skin, fat and muscle. As a result, the SAR in the vicinity of the transformer is sufficiently small and the normalized SAR value, which is divided by the ICNIRP's basic restriction, is 7 x 10(-3) or less. On the contrary, the current density is slightly in excess of the ICNIRP's basic restrictions as the frequency falls and the output voltage rises. Normalized current density is from 0.2 to 1.2. In addition, the layer in which the current's density is maximized depends on the frequency, the muscle in the low frequency (<700 kHz) and the skin in the high frequency (>700 kHz). The result shows that precision analysis taking into account the biological properties is very important for developing the transcutaneous transformer for TAH.

Sequence data and association statistics from 12,940 type 2 diabetes cases and controls

PubMed Central

Jason, Flannick; Fuchsberger, Christian; Mahajan, Anubha; Teslovich, Tanya M.; Agarwala, Vineeta; Gaulton, Kyle J.; Caulkins, Lizz; Koesterer, Ryan; Ma, Clement; Moutsianas, Loukas; McCarthy, Davis J.; Rivas, Manuel A.; Perry, John R. B.; Sim, Xueling; Blackwell, Thomas W.; Robertson, Neil R.; Rayner, N William; Cingolani, Pablo; Locke, Adam E.; Tajes, Juan Fernandez; Highland, Heather M.; Dupuis, Josee; Chines, Peter S.; Lindgren, Cecilia M.; Hartl, Christopher; Jackson, Anne U.; Chen, Han; Huyghe, Jeroen R.; van de Bunt, Martijn; Pearson, Richard D.; Kumar, Ashish; Müller-Nurasyid, Martina; Grarup, Niels; Stringham, Heather M.; Gamazon, Eric R.; Lee, Jaehoon; Chen, Yuhui; Scott, Robert A.; Below, Jennifer E.; Chen, Peng; Huang, Jinyan; Go, Min Jin; Stitzel, Michael L.; Pasko, Dorota; Parker, Stephen C. J.; Varga, Tibor V.; Green, Todd; Beer, Nicola L.; Day-Williams, Aaron G.; Ferreira, Teresa; Fingerlin, Tasha; Horikoshi, Momoko; Hu, Cheng; Huh, Iksoo; Ikram, Mohammad Kamran; Kim, Bong-Jo; Kim, Yongkang; Kim, Young Jin; Kwon, Min-Seok; Lee, Juyoung; Lee, Selyeong; Lin, Keng-Han; Maxwell, Taylor J.; Nagai, Yoshihiko; Wang, Xu; Welch, Ryan P.; Yoon, Joon; Zhang, Weihua; Barzilai, Nir; Voight, Benjamin F.; Han, Bok-Ghee; Jenkinson, Christopher P.; Kuulasmaa, Teemu; Kuusisto, Johanna; Manning, Alisa; Ng, Maggie C. Y.; Palmer, Nicholette D.; Balkau, Beverley; Stančáková, Alena; Abboud, Hanna E.; Boeing, Heiner; Giedraitis, Vilmantas; Prabhakaran, Dorairaj; Gottesman, Omri; Scott, James; Carey, Jason; Kwan, Phoenix; Grant, George; Smith, Joshua D.; Neale, Benjamin M.; Purcell, Shaun; Butterworth, Adam S.; Howson, Joanna M. M.; Lee, Heung Man; Lu, Yingchang; Kwak, Soo-Heon; Zhao, Wei; Danesh, John; Lam, Vincent K. L.; Park, Kyong Soo; Saleheen, Danish; So, Wing Yee; Tam, Claudia H. T.; Afzal, Uzma; Aguilar, David; Arya, Rector; Aung, Tin; Chan, Edmund; Navarro, Carmen; Cheng, Ching-Yu; Palli, Domenico; Correa, Adolfo; Curran, Joanne E.; Rybin, Dennis; Farook, Vidya S.; Fowler, Sharon P.; Freedman, Barry I.; Griswold, Michael; Hale, Daniel Esten; Hicks, Pamela J.; Khor, Chiea-Chuen; Kumar, Satish; Lehne, Benjamin; Thuillier, Dorothée; Lim, Wei Yen; Liu, Jianjun; Loh, Marie; Musani, Solomon K.; Puppala, Sobha; Scott, William R.; Yengo, Loïc; Tan, Sian-Tsung; Taylor, Herman A.; Thameem, Farook; Wilson, Gregory; Wong, Tien Yin; Njølstad, Pål Rasmus; Levy, Jonathan C.; Mangino, Massimo; Bonnycastle, Lori L.; Schwarzmayr, Thomas; Fadista, João; Surdulescu, Gabriela L.; Herder, Christian; Groves, Christopher J.; Wieland, Thomas; Bork-Jensen, Jette; Brandslund, Ivan; Christensen, Cramer; Koistinen, Heikki A.; Doney, Alex S. F.; Kinnunen, Leena; Esko, Tõnu; Farmer, Andrew J.; Hakaste, Liisa; Hodgkiss, Dylan; Kravic, Jasmina; Lyssenko, Valeri; Hollensted, Mette; Jørgensen, Marit E.; Jørgensen, Torben; Ladenvall, Claes; Justesen, Johanne Marie; Käräjämäki, Annemari; Kriebel, Jennifer; Rathmann, Wolfgang; Lannfelt, Lars; Lauritzen, Torsten; Narisu, Narisu; Linneberg, Allan; Melander, Olle; Milani, Lili; Neville, Matt; Orho-Melander, Marju; Qi, Lu; Qi, Qibin; Roden, Michael; Rolandsson, Olov; Swift, Amy; Rosengren, Anders H.; Stirrups, Kathleen; Wood, Andrew R.; Mihailov, Evelin; Blancher, Christine; Carneiro, Mauricio O.; Maguire, Jared; Poplin, Ryan; Shakir, Khalid; Fennell, Timothy; DePristo, Mark; de Angelis, Martin Hrabé; Deloukas, Panos; Gjesing, Anette P.; Jun, Goo; Nilsson, Peter; Murphy, Jacquelyn; Onofrio, Robert; Thorand, Barbara; Hansen, Torben; Meisinger, Christa; Hu, Frank B.; Isomaa, Bo; Karpe, Fredrik; Liang, Liming; Peters, Annette; Huth, Cornelia; O'Rahilly, Stephen P; Palmer, Colin N. A.; Pedersen, Oluf; Rauramaa, Rainer; Tuomilehto, Jaakko; Salomaa, Veikko; Watanabe, Richard M.; Syvänen, Ann-Christine; Bergman, Richard N.; Bharadwaj, Dwaipayan; Bottinger, Erwin P.; Cho, Yoon Shin; Chandak, Giriraj R.; Chan, Juliana CN; Chia, Kee Seng; Daly, Mark J.; Ebrahim, Shah B.; Langenberg, Claudia; Elliott, Paul; Jablonski, Kathleen A.; Lehman, Donna M.; Jia, Weiping; Ma, Ronald C. W.; Pollin, Toni I.; Sandhu, Manjinder; Tandon, Nikhil; Froguel, Philippe; Barroso, Inês; Teo, Yik Ying; Zeggini, Eleftheria; Loos, Ruth J. F.; Small, Kerrin S.; Ried, Janina S.; DeFronzo, Ralph A.; Grallert, Harald; Glaser, Benjamin; Metspalu, Andres; Wareham, Nicholas J.; Walker, Mark; Banks, Eric; Gieger, Christian; Ingelsson, Erik; Im, Hae Kyung; Illig, Thomas; Franks, Paul W.; Buck, Gemma; Trakalo, Joseph; Buck, David; Prokopenko, Inga; Mägi, Reedik; Lind, Lars; Farjoun, Yossi; Owen, Katharine R.; Gloyn, Anna L.; Strauch, Konstantin; Tuomi, Tiinamaija; Kooner, Jaspal Singh; Lee, Jong-Young; Park, Taesung; Donnelly, Peter; Morris, Andrew D.; Hattersley, Andrew T.; Bowden, Donald W.; Collins, Francis S.; Atzmon, Gil; Chambers, John C.; Spector, Timothy D.; Laakso, Markku; Strom, Tim M.; Bell, Graeme I.; Blangero, John; Duggirala, Ravindranath; Tai, E. Shyong; McVean, Gilean; Hanis, Craig L.; Wilson, James G.; Seielstad, Mark; Frayling, Timothy M.; Meigs, James B.; Cox, Nancy J.; Sladek, Rob; Lander, Eric S.; Gabriel, Stacey; Mohlke, Karen L.; Meitinger, Thomas; Groop, Leif; Abecasis, Goncalo; Scott, Laura J.; Morris, Andrew P.; Kang, Hyun Min; Altshuler, David; Burtt, Noël P.; Florez, Jose C.; Boehnke, Michael; McCarthy, Mark I.

2017-01-01

To investigate the genetic basis of type 2 diabetes (T2D) to high resolution, the GoT2D and T2D-GENES consortia catalogued variation from whole-genome sequencing of 2,657 European individuals and exome sequencing of 12,940 individuals of multiple ancestries. Over 27M SNPs, indels, and structural variants were identified, including 99% of low-frequency (minor allele frequency [MAF] 0.1–5%) non-coding variants in the whole-genome sequenced individuals and 99.7% of low-frequency coding variants in the whole-exome sequenced individuals. Each variant was tested for association with T2D in the sequenced individuals, and, to increase power, most were tested in larger numbers of individuals (>80% of low-frequency coding variants in ~82 K Europeans via the exome chip, and ~90% of low-frequency non-coding variants in ~44 K Europeans via genotype imputation). The variants, genotypes, and association statistics from these analyses provide the largest reference to date of human genetic information relevant to T2D, for use in activities such as T2D-focused genotype imputation, functional characterization of variants or genes, and other novel analyses to detect associations between sequence variation and T2D. PMID:29257133

Microfibrous metallic cloth for acoustic isolation of a MEMS gyroscope

NASA Astrophysics Data System (ADS)

Dean, Robert; Burch, Nesha; Black, Meagan; Beal, Aubrey; Flowers, George

2011-04-01

The response of a MEMS device that is exposed to a harsh environment may range from an increased noise floor to a completely erroneous output to temporary or even permanent device failure. One such harsh environment is high power acoustic energy possessing high frequency components. This type of environment sometimes occurs in small aerospace vehicles. In this type of operating environment, high frequency acoustic energy can be transferred to a MEMS gyroscope die through the device packaging. If the acoustic noise possesses a sufficiently strong component at the resonant frequency of the gyroscope, it will overexcite the motion of the proof mass, resulting in the deleterious effect of corrupted angular rate measurement. Therefore if the device or system packaging can be improved to sufficiently isolate the gyroscope die from environmental acoustic energy, the sensor may find new applications in this type of harsh environment. This research effort explored the use of microfibrous metallic cloth for isolating the gyroscope die from environmental acoustic excitation. Microfibrous cloth is a composite of fused, intermingled metal fibers and has a variety of typical uses involving chemical processing applications and filtering. Specifically, this research consisted of experimental evaluations of multiple layers of packed microfibrous cloth composed of sintered nickel material. The packed cloth was used to provide acoustic isolation for a test MEMS gyroscope, the Analog Devices ADXRS300. The results of this investigation revealed that the intermingling of the various fibers of the metallic cloth provided a significant contact area between the fiber strands and voids, which enhanced the acoustic damping of the material. As a result, the nickel cloth was discovered to be an effective acoustic isolation material for this particular MEMS gyroscope.

A novel type of very long baseline astronomical intensity interferometer

NASA Astrophysics Data System (ADS)

Borra, Ermanno F.

2013-12-01

This article presents a novel type of very long baseline astronomical interferometer that uses the fluctuations, as a function of time, of the intensity measured by a quadratic detector, which is a common type of astronomical detector. The theory on which the technique is based is validated by laboratory experiments. Its outstanding principal advantages comes from the fact that the angular structure of an astronomical object is simply determined from the visibility of the minima of the spectrum of the intensity fluctuations measured by the detector, as a function of the frequency of the fluctuations, while keeping the spacing between mirrors constant. This would allow a simple setup capable of high angular resolutions because it could use an extremely large baseline. Another major interest is that it allows for a more efficient use of telescope time because observations at a single baseline are sufficient, while amplitude and intensity interferometers need several observations at different baselines. The fact that one does not have to move the telescopes would also allow detecting faster time variations because having to move the telescopes sets a lower limit to the time variations that can be detected. The technique uses wave interaction effects and thus has some characteristics in common with intensity interferometry. A disadvantage of the technique, like in intensity interferometry, is that it needs strong sources if observing at high frequencies (e.g. the visible). This is a minor disadvantage in the radio region. At high frequencies, this disadvantage is mitigated by the fact that, like in intensity interferometry, the requirements of the optical quality of the mirrors used are far less severe than in amplitude interferometry so that poor quality large reflectors (e.g. Cherenkov telescopes) can be used in the optical region.

Input-output relation and energy efficiency in the neuron with different spike threshold dynamics.

PubMed

Yi, Guo-Sheng; Wang, Jiang; Tsang, Kai-Ming; Wei, Xi-Le; Deng, Bin

2015-01-01

Neuron encodes and transmits information through generating sequences of output spikes, which is a high energy-consuming process. The spike is initiated when membrane depolarization reaches a threshold voltage. In many neurons, threshold is dynamic and depends on the rate of membrane depolarization (dV/dt) preceding a spike. Identifying the metabolic energy involved in neural coding and their relationship to threshold dynamic is critical to understanding neuronal function and evolution. Here, we use a modified Morris-Lecar model to investigate neuronal input-output property and energy efficiency associated with different spike threshold dynamics. We find that the neurons with dynamic threshold sensitive to dV/dt generate discontinuous frequency-current curve and type II phase response curve (PRC) through Hopf bifurcation, and weak noise could prohibit spiking when bifurcation just occurs. The threshold that is insensitive to dV/dt, instead, results in a continuous frequency-current curve, a type I PRC and a saddle-node on invariant circle bifurcation, and simultaneously weak noise cannot inhibit spiking. It is also shown that the bifurcation, frequency-current curve and PRC type associated with different threshold dynamics arise from the distinct subthreshold interactions of membrane currents. Further, we observe that the energy consumption of the neuron is related to its firing characteristics. The depolarization of spike threshold improves neuronal energy efficiency by reducing the overlap of Na(+) and K(+) currents during an action potential. The high energy efficiency is achieved at more depolarized spike threshold and high stimulus current. These results provide a fundamental biophysical connection that links spike threshold dynamics, input-output relation, energetics and spike initiation, which could contribute to uncover neural encoding mechanism.

Input-output relation and energy efficiency in the neuron with different spike threshold dynamics

PubMed Central

Yi, Guo-Sheng; Wang, Jiang; Tsang, Kai-Ming; Wei, Xi-Le; Deng, Bin

2015-01-01

Neuron encodes and transmits information through generating sequences of output spikes, which is a high energy-consuming process. The spike is initiated when membrane depolarization reaches a threshold voltage. In many neurons, threshold is dynamic and depends on the rate of membrane depolarization (dV/dt) preceding a spike. Identifying the metabolic energy involved in neural coding and their relationship to threshold dynamic is critical to understanding neuronal function and evolution. Here, we use a modified Morris-Lecar model to investigate neuronal input-output property and energy efficiency associated with different spike threshold dynamics. We find that the neurons with dynamic threshold sensitive to dV/dt generate discontinuous frequency-current curve and type II phase response curve (PRC) through Hopf bifurcation, and weak noise could prohibit spiking when bifurcation just occurs. The threshold that is insensitive to dV/dt, instead, results in a continuous frequency-current curve, a type I PRC and a saddle-node on invariant circle bifurcation, and simultaneously weak noise cannot inhibit spiking. It is also shown that the bifurcation, frequency-current curve and PRC type associated with different threshold dynamics arise from the distinct subthreshold interactions of membrane currents. Further, we observe that the energy consumption of the neuron is related to its firing characteristics. The depolarization of spike threshold improves neuronal energy efficiency by reducing the overlap of Na+ and K+ currents during an action potential. The high energy efficiency is achieved at more depolarized spike threshold and high stimulus current. These results provide a fundamental biophysical connection that links spike threshold dynamics, input-output relation, energetics and spike initiation, which could contribute to uncover neural encoding mechanism. PMID:26074810

Passive millimetre wave imaging for ballistic missile launch detection

NASA Astrophysics Data System (ADS)

Higgins, Christopher J.; Salmon, Neil A.

2008-10-01

QinetiQ has used a suite of modelling tools to predict the millimetric plume signatures from a range of ballistic missile types, based on the accepted theory that Bremsstrahlung emission, generated by the collision of free electrons with neutral species in a rocket motor plume, is the dominant signature mechanism. Plume signatures in terms of radiation temperatures varied from a few hundred Kelvin to over one thousand Kelvin, and were predicted to be dependent on emission frequency, propellant type and missile thrust. Two types of platform were considered for the passive mmw imager launch detection system; a High Altitude Platform Station (HAPS) and a satellite based platform in low, mid and geosynchronous earth orbits. It was concluded that the optimum operating frequency for a HAPS based imager would be 35GHz with a 4.5m aperture and a sensitivity of 20mK providing visibility through 500 vertical feet of cloud. For a satellite based platform with a nadir view, the optimum frequency is 220 GHz. With such a system, in a low earth orbit at an altitude of 320km, with a sensitivity of 20mK, a 29cm aperture would be desirable.

Use of Public Libraries by Middle and High School Students in DeKalb County, Georgia.

ERIC Educational Resources Information Center

Enujioke, Emmanuel

The purpose of this study was to determine factors that influence middle and high school students' use of public libraries, the type of materials they use, and the frequency with which students use public libraries compared to the students' use of school library media centers. A questionnaire was used as the data gathering instrument. It was…

[Effect of coherent extremely high-frequency and low-intensity electromagnetic radiation on the activity of membrane systems in Escherichia coli].

PubMed

Tadevosian, A; Trchunian, A

2009-01-01

It has been shown that the exposure of wild-type Escherichia coli K12 bacteria grown in anaerobic conditions upon fermentation of glucose to coherent extremely high-frequency (51.8 and 53 GHz) electromagnetic radiation (EMR) or millimeter waves (wavelength 5.8 to 6.7 mm) of low intensity (flux capacity 0.06 mW/cm2) caused a marked decrease in energy-dependent and N,N'-dicyclohexylcarbodiimide- or azide-sensitive proton and potassium ions transport fluxes through the membrane, including proton fluxes via proton F0F1-ATPase and through the potassium uptake Trk system, correspondingly. K+ uptake was less for the E. coli mutant Trk 1110. The rate of molecular hydrogen production by formate hydrogen lyase 2 is strongly inhibited. The results indicate that the bacterial effect of coherent extremely high-frequency EMR includes changes in the activity of membrane transport and enzymatic systems in which the F0F1-ATPase plays a key role.

Dynein-deficient flagella respond to increased viscosity with contrasting changes in power and recovery strokes.

PubMed

Wilson, Kate S; Gonzalez, Olivia; Dutcher, Susan K; Bayly, Philip V

2015-09-01

Changes in the flagellar waveform in response to increased viscosity were investigated in uniflagellate mutants of Chlamydomonas reinhardtii. We hypothesized that the waveforms of mutants lacking different dynein arms would change in different ways as viscosity was increased, and that these variations would illuminate the feedback pathways from force to dynein activity. Previous studies have investigated the effects of viscosity on cell body motion, propulsive force, and power in different mutants, but the effect on waveform has not yet been fully characterized. Beat frequency decreases with viscosity in wild-type uniflagellate (uni1) cells, and outer dynein arm deficient (oda2) mutants. In contrast, the inner dynein arm mutant ida1 (lacking I1/f) maintains beat frequency at high viscosity but alters its flagellar waveform more than either wild-type or oda2. The ida1 waveform is narrower than wild-type, primarily due to an abbreviated recovery stroke; this difference is amplified at high viscosity. The oda2 mutant in contrast, maintains a consistent waveform at high and low viscosity with a slightly longer power stroke than wild-type. Analysis of the delays and shear displacements between bends suggest that direct force feedback in the outer dynein arm system may initiate switching of dynein activity. In contrast, I1/f dynein appears to delay switching, most markedly at the initiation of the power stroke, possibly by controlling inter-doublet separation. © 2015 Wiley Periodicals, Inc.

Dynein-deficient flagella respond to increased viscosity with contrasting changes in power and recovery strokes

PubMed Central

Wilson, Kate S.; Gonzalez, Olivia; Dutcher, Susan K.; Bayly, P.V.

2015-01-01

Changes in the flagellar waveform in response to increased viscosity were investigated in uniflagellate mutants of Chlamydomonas reinhardtii. We hypothesized that the waveforms of mutants lacking different dynein arms would change in different ways as viscosity was increased, and that these variations would illuminate the feedback pathways from force to dynein activity. Previous studies have investigated the effects of viscosity on cell body motion, propulsive force, and power in different mutants, but the effect on waveform has not yet been fully characterized. Beat frequency decreases with viscosity in wild-type uniflagellate (uni1) cells, and outer dynein arm deficient (oda2) mutants. In contrast, the inner dynein arm mutant ida1 (lacking I1/f) maintains beat frequency at high viscosity but alters its flagellar waveform more than either wild-type or oda2. The ida1 waveform is narrower than wild-type, primarily due to an abbreviated recovery stroke; this difference is amplified at high viscosity. The oda2 mutant in contrast, maintains a consistent waveform at high and low viscosity with a slightly longer power stroke than wild-type. Analysis of the delays and shear displacements between bends suggest that direct force feedback in the outer dynein arm system may initiate switching of dynein activity. In contrast, I1/f dynein appears to delay switching, most markedly at the initiation of the power stroke, possibly by controlling inter-doublet separation. PMID:26314933

Nucleotide excision repair and recombination are engaged in repair of trans-4-hydroxy-2-nonenal adducts to DNA bases in Escherichia coli.

PubMed

Janowska, Beata; Komisarski, Marek; Prorok, Paulina; Sokołowska, Beata; Kuśmierek, Jarosław; Janion, Celina; Tudek, Barbara

2009-09-23

One of the major products of lipid peroxidation is trans-4-hydroxy-2-nonenal (HNE). HNE forms highly mutagenic and genotoxic adducts to all DNA bases. Using M13 phage lacZ system, we studied the mutagenesis and repair of HNE treated phage DNA in E. coli wild-type or uvrA, recA, and mutL mutants. These studies revealed that: (i) nucleotide excision and recombination, but not mismatch repair, are engaged in repair of HNE adducts when present in phage DNA replicating in E. coli strains; (ii) in the single uvrA mutant, phage survival was drastically decreased while mutation frequency increased, and recombination events constituted 48% of all mutations; (iii) in the single recA mutant, the survival and mutation frequency of HNE-modified M13 phage was slightly elevated in comparison to that in the wild-type bacteria. The majority of mutations in recA(-) strain were G:C --> T:A transversions, occurring within the sequence which in recA(+) strains underwent RecA-mediated recombination, and the entire sequence was deleted; (iv) in the double uvrA recA mutant, phage survival was the same as in the wild-type although the mutation frequency was higher than in the wild-type and recA single mutant, but lower than in the single uvrA mutant. The majority of mutations found in the latter strain were base substitutions, with G:C --> A:T transitions prevailing. These transitions could have resulted from high reactivity of HNE with G and C, and induction of SOS-independent mutations.

Nucleotide excision repair and recombination are engaged in repair of trans-4-hydroxy-2-nonenal adducts to DNA bases in Escherichia coli

PubMed Central

Janowska, Beata; Komisarski, Marek; Prorok, Paulina; Sokołowska, Beata; Kuśmierek, Jarosław; Janion, Celina; Tudek, Barbara

2009-01-01

One of the major products of lipid peroxidation is trans-4-hydroxy-2-nonenal (HNE). HNE forms highly mutagenic and genotoxic adducts to all DNA bases. Using M13 phage lacZ system, we studied the mutagenesis and repair of HNE treated phage DNA in E. coli wild-type or uvrA, recA, and mutL mutants. These studies revealed that: (i) nucleotide excision and recombination, but not mismatch repair, are engaged in repair of HNE adducts when present in phage DNA replicating in E. coli strains; (ii) in the single uvrA mutant, phage survival was drastically decreased while mutation frequency increased, and recombination events constituted 48 % of all mutations; (iii) in the single recA mutant, the survival and mutation frequency of HNE-modified M13 phage was slightly elevated in comparison to that in the wild-type bacteria. The majority of mutations in recA- strain were G:C → T:A transversions, occurring within the sequence which in recA+ strains underwent RecA-mediated recombination, and the entire sequence was deleted; (iv) in the double uvrA recA mutant, phage survival was the same as in the wild-type although the mutation frequency was higher than in the wild-type and recA single mutant, but lower than in the single uvrA mutant. The majority of mutations found in the latter strain were base substitutions, with G:C → A:T transitions prevailing. These transitions could have resulted from high reactivity of HNE with G and C, and induction of SOS-independent mutations. PMID:19834545