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Sample records for frequency separation variations

  1. Solar-cycle variations of large frequency separations of acoustic modes: implications for asteroseismology

    NASA Astrophysics Data System (ADS)

    Broomhall, A.-M.; Chaplin, W. J.; Elsworth, Y.; New, R.

    2011-06-01

    We have studied solar-cycle changes in the large frequency separations that can be observed in Birmingham Solar Oscillations Network (BiSON) data. The large frequency separation is often one of the first outputs from asteroseismic studies because it can help constrain stellar properties like mass and radius. We have used three methods for estimating the large separations: use of individual p-mode frequencies, computation of the autocorrelation of frequency-power spectra, and computation of the power spectrum of the power spectrum. The values of the large separations obtained by the different methods are offset from each other and have differing sensitivities to the realization noise. A simple model was used to predict solar-cycle variations in the large separations, indicating that the variations are due to the well-known solar-cycle changes to mode frequency. However, this model is only valid over a restricted frequency range. We discuss the implications of these results for asteroseismology.

  2. Frequency-offset separated oscillatory fields

    NASA Astrophysics Data System (ADS)

    Vutha, A. C.; Hessels, E. A.

    2015-11-01

    A frequency-offset separated-oscillatory-field technique is presented. The technique is a modification of the Ramsey method of separated oscillatory fields [Phys. Rev. 76, 996 (1949), 10.1103/PhysRev.76.996], in which the frequencies of the two separated oscillatory fields are slightly offset from each other, so that the relative phase of the two fields varies continuously with time. With this technique, the detection signal oscillates in time at the offset frequency, and the resonance frequency is obtained by using a simple straight-line fit of the phase of this signal. The technique has the advantages of being insensitive to the frequency response of the experimental system, of being sensitive only to noise at the offset frequency, and of allowing systematic effects to be more cleanly resolved due to the simple lineshape.

  3. Frequency-offset separated oscillatory fields technique

    NASA Astrophysics Data System (ADS)

    Bezginov, N.; Vutha, A. C.; Ferchichi, I.; Storry, C. H.; Hessels, E. A.

    2015-05-01

    Improved measurements in atomic hydrogen are needed to shed light on the proton radius puzzle. We are measuring the Lamb shift in hydrogen (n = 2 ,S1 / 2 -->P1 / 2) using a frequency-offset separated oscillatory fields (FOSOF) method. The advantages of this method include its insensitivity to atomic beam intensity fluctuations and the microwave-system frequency response. We present experimental results obtained with this method, towards a new measurement of the proton charge radius. We acknowledge funding from NSERC, CFI, CRC, ORF, and NIST.

  4. 47 CFR 76.612 - Cable television frequency separation standards.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Cable television frequency separation standards... frequency separation standards. All cable television systems which operate in the frequency bands 108-137 and 225-400 MHz shall comply with the following frequency separation standards: (a) In...

  5. 47 CFR 76.612 - Cable television frequency separation standards.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Cable television frequency separation standards... frequency separation standards. All cable television systems which operate in the frequency bands 108-137 and 225-400 MHz shall comply with the following frequency separation standards: (a) In...

  6. 47 CFR 76.612 - Cable television frequency separation standards.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Cable television frequency separation standards... frequency separation standards. All cable television systems which operate in the frequency bands 108-137 and 225-400 MHz shall comply with the following frequency separation standards: (a) In...

  7. Separation of musical instruments based on amplitude and frequency comodulation

    NASA Astrophysics Data System (ADS)

    Jacobson, Barry D.; Cauwenberghs, Gert; Quatieri, Thomas F.

    2002-05-01

    In previous work, amplitude comodulation was investigated as a basis for monaural source separation. Amplitude comodulation refers to similarities in amplitude envelopes of individual spectral components emitted by particular types of sources. In many types of musical instruments, amplitudes of all resonant modes rise/fall, and start/stop together during the course of normal playing. We found that under certain well-defined conditions, a mixture of constant frequency, amplitude comodulated sources can unambiguously be decomposed into its constituents on the basis of these similarities. In this work, system performance was improved by relaxing the constant frequency requirement. String instruments, for example, which are normally played with vibrato, are both amplitude and frequency comodulated sources, and could not be properly tracked under the constant frequency assumption upon which our original algorithm was based. Frequency comodulation refers to similarities in frequency variations of individual harmonics emitted by these types of sources. The analytical difficulty is in defining a representation of the source which properly tracks frequency varying components. A simple, fixed filter bank can only track an individual spectral component for the duration in which it is within the passband of one of the filters. Alternatives are therefore explored which are amenable to real-time implementation.

  8. 47 CFR 76.612 - Cable television frequency separation standards.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Cable television frequency separation standards. 76.612 Section 76.612 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Technical Standards § 76.612 Cable...

  9. On variation of word frequencies in Russian literary texts

    NASA Astrophysics Data System (ADS)

    Kargin, Vladislav

    2016-03-01

    We study the variation of word frequencies in Russian literary texts. Our findings indicate that the standard deviation of a word's frequency across texts depends on its average frequency according to a power law with exponent 1/2 < α < 1, which shows that the rarer words have a relatively larger degree of frequency volatility (that is, higher "burstiness"). A latent factor model has been estimated to investigate the structure of the word frequency distribution. The findings suggest that the dependence of a word's frequency volatility on its average frequency can be explained by the asymmetry in the distribution of latent factors.

  10. CW dual-frequency MOPA laser with frequency separation of 45 GHz.

    PubMed

    Hu, Miao; Zheng, Yaoyuan; Cai, Ju; Zhang, Guiju; Li, Qiliang; Zhou, Xuefang; Wei, Yizhen; Lu, Yang

    2015-04-20

    A CW dual-frequency master oscillator power amplifier (MOPA) laser system with dozens of gigahertz (GHz) frequency separation is presented. The MOPA system consists of a monolithic microchip seed laser and a double-end pumped traveling wave power amplifier. The short length of seed laser cavity guarantees the seed signal with a large frequency separation (above 53 GHz) but low output power (below 247.8 mW). By adding a long and low-doped active medium laser amplifier stage, a significant increase in laser power and an improvement in beam quality are obtained. After fine temperature tuning of seed laser cavity for "spectra matching", a 2.40 W dual-frequency laser signal with 45 GHz frequency separation is achieved.

  11. Development of a frequency-separated knob with variable change rates by rotation speed.

    PubMed

    Kim, Huhn; Ham, Dong-Han

    2014-11-01

    The principle of frequency separation is a design method to display different information or feedback in accordance with the frequency of interaction between users and systems. This principle can be usefully applied to the design of knobs. Particularly, their rotation speed can be a meaningful criterion for applying the principle. Hence a knob can be developed, which shows change rates varying depending on its rotation speed. Such a knob would be more efficient than conventional knobs with constant change rate. We developed a prototype of frequency-separated knobs that has different combinations of the number of rotation speed steps and the size of the variation of change rate. With this prototype, we conducted an experiment to examine whether a speed frequency-separated knob enhances users' task performance. The results showed that the newly designed knob was effective in enhancing task performance, and that task efficiency was the best when its change rate increases exponentially and its rotation speed has three steps. We conducted another experiment to investigate how a more rapid exponential increase of change rate and a more number of steps of rotation speed influence users' task performance. The results showed that merely increasing both the size of the variation of change rates and the number of speed steps did not result in better task performance. Although two experimental results cannot easily be generalized to other contexts, they still offer practical information useful for designing a speed frequency-separated knob in various consumer electronics and control panels of industrial systems.

  12. Interdecadal variation of TC frequency in Japan

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seon; Cha, Yu-Mi; Kang, Sung-Dae; Kim, Hae-Dong

    2015-07-01

    This study analyzed the climate regime shift using statistical change-point analysis on the time-series tropical cyclone (TC) frequency that affected Japan in July to September. The result showed that there was a significant change in 1995, and since then, it showed a trend of rapidly decreasing frequency. To determine the reason for this, differences between 1995 to 2012 (9512) period and 1978 to 1994 (7894) period were analyzed. First, regarding TC genesis, TCs during the 9512 period showed a characteristic of genesis from the southeast quadrant of the tropical and subtropical western North Pacific and TCs during the 7894 period showed their genesis from the northwest quadrant. Regarding a TC track, TCs in the 7894 period had a strong trend of moving from the far east sea of the Philippines via the East China Sea to the mid-latitude region in East Asia while TCs in the 9512 period showed a trend of moving from the Philippines toward the southern part of China westward. Thus, TC intensity in the 7894 period, which can absorb sufficient energy from the sea as they moved a long distance over the sea, was stronger than that of 9512. Large-scale environments were analyzed to determine the cause of such difference in TC activity occurred between two periods. During the 9512 period, anomalous cold and dry anticyclones were developed strongly in the East Asia continent. As a result, Korea and Japan were affected by the anomalous northerlies thereby preventing TCs in this period from moving toward the mid-latitude region in East Asia. Instead, anomalous easterlies (anomalous trade wind) were developed in the tropical western Pacific so that a high passage frequency from the Philippines to the south China region along the anomalous steering flows was revealed. The characteristics of the anomalous cold and dry anticyclone developed in the East Asia continent were also confirmed by the analysis of air temperature, relative humidity, and sensible heat net flux showing that

  13. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ....01-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated, electrical equipment must function at variations of at least ±5 percent of rated...

  14. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ....01-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated, electrical equipment must function at variations of at least ±5 percent of rated...

  15. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ....01-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated, electrical equipment must function at variations of at least ±5 percent of rated...

  16. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ....01-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated, electrical equipment must function at variations of at least ±5 percent of rated...

  17. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....01-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated, electrical equipment must function at variations of at least ±5 percent of rated...

  18. Solution of high frequency variations of ERP from VLBI observations

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Li, J. L.; Wang, G. L.; Zhao, M.

    2005-01-01

    In the astrometric and geodetic VLBI data analysis software CALC/SOLVE, the high frequency variations of the Earth Rotation Parameters (ERP) are determined by a constrained continuous piecewise linear model. The ERP rate within two epoch nodes is constrained to be smaller than a limitation setting, and the ERP is forced to be continuous at epoch nodes. Observation analysis shows that when the data points are not very dense the constraint and the continuation requirement are helpful to the improvement in the stability of the solution, but degrade the independence of ERP solutions at epoch nodes as well. By using the Userpartial entry of CALC/SOLVE a direct solution module of the high frequency variations of ERP is realized without any constraint on the rate nor the requirement of continuation at nodes. It is shown from real observation reduction that the direct solution mode is feasible. In the solution of high frequency variations of ERP from VLBI observations with long period coverage, the model errors of the precession and nutation (celestial pole offset) should be taken into consideration. A corresponding module is realized and global solutions of the high frequency variation of ERP are successfully performed on the VLBI observations from 1979 to 2003. Comparison of the solutions shows that with the consideration of the pole offsets the precision of parameters could be improved obviously. In the solution of high frequency variation of ERP from VLBI observations, the direct solution mode with the consideration of the pole offsets is accordingly recommended.

  19. Os incae: variation in frequency in major human population groups

    PubMed Central

    HANIHARA, TSUNEHIKO; ISHIDA, HAJIME

    2001-01-01

    The variation in frequency of the Inca bone was examined in major human populations around the world. The New World populations have generally high frequencies of the Inca bone, whereas lower frequencies occur in northeast Asians and Australians. Tibetan/Nepalese and Assam/Sikkim populations in northeast India have more Inca bones than do neighbouring populations. Among modern populations originally derived from eastern Asian population stock, the frequencies are highest in some of the marginal isolated groups. In Central and West Asia as well as in Europe, frequency of the Inca bone is relatively low. The incidence of the complete Inca bone is, moreover, very low in the western hemisphere of the Old World except for Subsaharan Africa. Subsaharan Africans show as a whole a second peak in the occurrence of the Inca bone. Geographical and ethnographical patterns of the frequency variation of the Inca bone found in this study indicate that the possible genetic background for the occurrence of this bone cannot be completely excluded. Relatively high frequencies of the Inca bone in Subsaharan Africans indicate that this trait is not a uniquely eastern Asian regional character. PMID:11273039

  20. On the variation of interaural time differences with frequency.

    PubMed

    Benichoux, Victor; Rébillat, Marc; Brette, Romain

    2016-04-01

    Interaural time difference (ITD) is a major cue to sound localization in humans and animals. For a given subject and position in space, ITD depends on frequency. This variation is analyzed here using a head related transfer functions (HRTFs) database collected from the literature and comprising human HRTFs from 130 subjects and animal HRTFs from six specimens of different species. For humans, the ITD is found to vary with frequency in a way that shows consistent differences with respect to a spherical head model. Maximal ITD values were found to be about 800 μs in low frequencies and 600 μs in high frequencies. The ITD variation with frequency (up to 200 μs for some positions) occurs within the frequency range where ITD is used to judge the lateral position of a sound source. In addition, ITD varies substantially within the bandwidth of a single auditory filter, leading to systematic differences between envelope and fine-structure ITDs. Because the frequency-dependent pattern of ITD does not display spherical symmetries, it potentially provides cues to elevation and resolves front/back confusion. The fact that the relation between position and ITDs strongly depends on the sound's spectrum in turn suggests that humans and animals make use of this relationship for the localization of sounds.

  1. Ion mobility spectrometer using frequency-domain separation

    DOEpatents

    Martin, S.J.; Butler, M.A.; Frye, G.C.; Schubert, W.K.

    1998-08-04

    An apparatus and method are provided for separating and analyzing chemical species in an ion mobility spectrometer using a frequency-domain technique wherein the ions generated from the chemical species are selectively transported through an ion flow channel having a moving electrical potential therein. The moving electrical potential allows the ions to be selected according to ion mobility, with certain of the ions being transported to an ion detector and other of the ions being effectively discriminated against. The apparatus and method have applications for sensitive chemical detection and analysis for monitoring of exhaust gases, hazardous waste sites, industrial processes, aerospace systems, non-proliferation, and treaty verification. The apparatus can be formed as a microelectromechanical device (i.e. a micromachine). 6 figs.

  2. Ion mobility spectrometer using frequency-domain separation

    DOEpatents

    Martin, Stephen J.; Butler, Michael A.; Frye, Gregory C.; Schubert, W. Kent

    1998-01-01

    An apparatus and method is provided for separating and analyzing chemical species in an ion mobility spectrometer using a frequency-domain technique wherein the ions generated from the chemical species are selectively transported through an ion flow channel having a moving electrical potential therein. The moving electrical potential allows the ions to be selected according to ion mobility, with certain of the ions being transported to an ion detector and other of the ions being effectively discriminated against. The apparatus and method have applications for sensitive chemical detection and analysis for monitoring of exhaust gases, hazardous waste sites, industrial processes, aerospace systems, non-proliferation, and treaty verification. The apparatus can be formed as a microelectromechanical device (i.e. a micromachine).

  3. Peculiar variations of white dwarf pulsation frequencies and maestro

    NASA Astrophysics Data System (ADS)

    Dalessio, James Ruland

    In Part I we report on variations of the normal mode frequencies of the pulsating DB white dwarfs EC 20058-5234 and KIC 8626021 and the pulsating DA white dwarf GD 66. The observations of EC 20058-5234 and KIC 8626021 were motivated by the possibility of measuring the plasmon neutrino production rate of a white dwarf, while the observations of GD 66 were part of a white dwarf pulsation timing based planet search. We announce the discovery of periodic and quasi-periodic variations of multiple normal mode frequencies that cannot be due to the presence of planetary companions. We note the possible signature of a planetary companion to EC 20058-5234 and show that GD 66 cannot have a planet in a several AU orbit down to half a Jupiter mass. We also announce the discovery of secular variations of the normal mode frequencies of all three stars that are inconsistent with cooling alone. Importantly, the rates of period change of several modes of KIC 8626021 are consistent with evolutionary cooling, but are not yet statistically significant. These modes offer the best possibility of measuring the neutrino production rate in a white dwarf. We also observe periodic and secular variations in the frequency of a combination mode that exactly matches the variations predicted by the parent modes, strong observational evidence that combination modes are created by the convection zone and are not normal modes. Periodic variations in the amplitudes of many of these modes is also noted. We hypothesize that these frequency variations are caused by complex variations of the magnetic field strength and geometry, analogous to behavior observed in the Sun. In Part II we describe the MAESTRO software framework and the MAESTRO REDUCE algorithm. MAESTRO is a collection of astronomy specific MatLab software developed by the Whole Earth Telescope. REDUCE is an an algorithm that can extract the brightness of stars on a set of CCD images with minimal configuration and human interaction. The key to

  4. Gravitational dynamos and the low-frequency geomagnetic secular variation.

    PubMed

    Olson, P

    2007-12-18

    Self-sustaining numerical dynamos are used to infer the sources of low-frequency secular variation of the geomagnetic field. Gravitational dynamo models powered by compositional convection in an electrically conducting, rotating fluid shell exhibit several regimes of magnetic field behavior with an increasing Rayleigh number of the convection, including nearly steady dipoles, chaotic nonreversing dipoles, and chaotic reversing dipoles. The time average dipole strength and dipolarity of the magnetic field decrease, whereas the dipole variability, average dipole tilt angle, and frequency of polarity reversals increase with Rayleigh number. Chaotic gravitational dynamos have large-amplitude dipole secular variation with maximum power at frequencies corresponding to a few cycles per million years on Earth. Their external magnetic field structure, dipole statistics, low-frequency power spectra, and polarity reversal frequency are comparable to the geomagnetic field. The magnetic variability is driven by the Lorentz force and is characterized by an inverse correlation between dynamo magnetic and kinetic energy fluctuations. A constant energy dissipation theory accounts for this inverse energy correlation, which is shown to produce conditions favorable for dipole drift, polarity reversals, and excursions. PMID:18048345

  5. Frequency variations of discrete cranial traits in major human populations. I. Supernumerary ossicle variations

    PubMed Central

    HANIHARA, TSUNEHIKO; ISHIDA, HAJIME

    2001-01-01

    Four supernumerary ossicle variations—the ossicle at the lambda, the parietal notch bone, the asterionic bone, and the occipitomastoid bone—were examined for laterality differences, intertrait correlations, sex differences, and between group variations in the samples from around the world. Significant laterality differences were not detected in almost all samples. In some pairs of traits, significant association of occurrence were found. Several geographic samples were sexually dimorphic with respect to the asterionic bone and to a lesser extent for the parietal notch bone. East/Northeast Asians including the Arctic populations in general had lower frequencies of the 4 accessory ossicles. Australians, Melanesians and the majority of the New World peoples, on the other hand, generally had high frequencies. In the western hemisphere of the Old World, Subsaharan Africans had relatively high frequencies. Except for the ossicle at the lambda, the distribution pattern in incidence showed clinal variation from south to north. Any identifiable adaptive value related to environmental or subsistence factors may be expressed in such clinal variation. This may allow us to hypothesise that not only mechanical factors but a founder effect, genetic drift, and population structure could have been the underlying causes for interregional variation and possible clines in the incidences of the accessory ossicles. PMID:11465862

  6. Commissioning of helium injector for coupled radio frequency quadrupole and separated function radio frequency quadrupole accelerator

    SciTech Connect

    Peng, Shixiang Chen, Jia; Ren, Haitao; Zhao, Jie; Xu, Yuan; Zhang, Tao; Xia, Wenlong; Gao, Shuli; Wang, Zhi; Luo, Yuting; Guo, Zhiyu; Zhang, Ailing; Chen, Jia'er

    2014-02-15

    A project to study a new type of acceleration structure has been launched at Peking University, in which a traditional radio frequency quadrupole (RFQ) and a separated function radio frequency quadrupole are coupled in one cavity to accelerate the He+ beam. A helium injector for this project is developed. The injector consists of a 2.45 GHz permanent magnet electron cyclotron resonance ion source and a 1.16 m long low energy beam transport (LEBT). The commissioning of this injector was carried out and an onsite test was held in June 2013. A 14 mA He+ beam with the energy of 30 keV has been delivered to the end of the LEBT, where a diaphragm with the diameter of 7 mm is located. The position of the diaphragm corresponds to the entrance of the RFQ electrodes. The beam emittance and fraction were measured after the 7 mm diaphragm. Its rms emittance is about 0.14 π mm mrad and the fraction of He+ is about 99%.

  7. Commissioning of helium injector for coupled radio frequency quadrupole and separated function radio frequency quadrupole accelerator.

    PubMed

    Peng, Shixiang; Chen, Jia; Ren, Haitao; Zhao, Jie; Xu, Yuan; Zhang, Tao; Zhang, Ailing; Xia, Wenlong; Gao, Shuli; Wang, Zhi; Luo, Yuting; Guo, Zhiyu; Chen, Jia'er

    2014-02-01

    A project to study a new type of acceleration structure has been launched at Peking University, in which a traditional radio frequency quadrupole (RFQ) and a separated function radio frequency quadrupole are coupled in one cavity to accelerate the He+ beam. A helium injector for this project is developed. The injector consists of a 2.45 GHz permanent magnet electron cyclotron resonance ion source and a 1.16 m long low energy beam transport (LEBT). The commissioning of this injector was carried out and an onsite test was held in June 2013. A 14 mA He+ beam with the energy of 30 keV has been delivered to the end of the LEBT, where a diaphragm with the diameter of 7 mm is located. The position of the diaphragm corresponds to the entrance of the RFQ electrodes. The beam emittance and fraction were measured after the 7 mm diaphragm. Its rms emittance is about 0.14 π mm mrad and the fraction of He+ is about 99%.

  8. Designing structures for dynamical properties via natural frequencies separation. Application to tensegrity structures design

    NASA Astrophysics Data System (ADS)

    Sultan, Cornel

    2009-05-01

    The design of structures for dynamic properties is addressed by placing conditions on the separation between natural frequencies. Additional constraints, like lower and upper bounds on the natural frequencies, are also included. A fast numerical algorithm that exploits the mathematical structure of the resulting problem is developed. Examples of the algorithm's application to tensegrity structures design are presented and the connection between natural frequencies separation and proportional damping approximation is analyzed.

  9. Radio-frequency ion deflector for mass separation

    SciTech Connect

    Schlösser, Magnus Rudnev, Vitaly; Ureña, Ángel González

    2015-10-15

    Electrostatic cylindrical deflectors act as energy analyzer for ion beams. In this article, we present that by imposing of a radio-frequency modulation on the deflecting electric field, the ion transmission becomes mass dependent. By the choice of the appropriate frequency, amplitude, and phase, the deflector can be used as mass filter. The basic concept of the new instrument as well as simple mathematic relations are described. These calculations and further numerical simulations show that a mass sensitivity is achievable. Furthermore, we demonstrate the proof-of-principle in experimental measurements, compare the results to those of from a 1 m linear time-of-flight spectrometer, and comment on the mass resolution of the method. Finally, some potential applications are indicated.

  10. Radio-frequency ion deflector for mass separation.

    PubMed

    Schlösser, Magnus; Rudnev, Vitaly; González Ureña, Ángel

    2015-10-01

    Electrostatic cylindrical deflectors act as energy analyzer for ion beams. In this article, we present that by imposing of a radio-frequency modulation on the deflecting electric field, the ion transmission becomes mass dependent. By the choice of the appropriate frequency, amplitude, and phase, the deflector can be used as mass filter. The basic concept of the new instrument as well as simple mathematic relations are described. These calculations and further numerical simulations show that a mass sensitivity is achievable. Furthermore, we demonstrate the proof-of-principle in experimental measurements, compare the results to those of from a 1 m linear time-of-flight spectrometer, and comment on the mass resolution of the method. Finally, some potential applications are indicated. PMID:26520948

  11. The role of low-frequency variation in the manifestation of warming trend and ENSO amplitude

    NASA Astrophysics Data System (ADS)

    Yeo, Sae-Rim; Yeh, Sang-Wook; Kim, Kwang-Yul; Kim, WonMoo

    2016-10-01

    Despite the increase in greenhouse gas concentration, the sea surface temperature (SST) over the tropical eastern Pacific during the period of 1999-2014 exhibits less warming trend compared to the earlier decades. It has been noted that this warming hiatus is accompanied by a negative phase of the Pacific Decadal Oscillation (PDO), which represents low-frequency variability over the Pacific. On the other hand, the 2015/2016 El Niño is among the strongest comparable to the 1997/1998 event, which coincides with the recently altered PDO phase from negative to positive. These observational evidences have generated substantial interest in the role of low-frequency variations in modulating El Niño-Southern Oscillation amplitude as well as manifestation of warming signal in the tropical Pacific. Therefore, it is necessary to appropriately separate low-frequency variability and global warming signal from SST records. Here, we present three primary modes of global SST that include secular warming trend, low-frequency variability, and biennial oscillation. Based on the independent behavior of these three modes, global warming is clearly continuing but its manifestation is enhanced (depressed) when the low-frequency variation is in the positive (negative) phase. Further, possibility of strong El Niño increases under the positive phase of the low-frequency mode, which amplifies warming over the tropical eastern Pacific. Indeed, the strong 2015/2016 El Niño is largely attributed to the positive phase of the low-frequency mode. In order to examine the climate models' ability to simulate the three SST modes as obtained in the observational record, the Coupled Model Intercomparison Project phase 5 (CMIP5) datasets are also analyzed. The spatial and temporal characteristics of the three modes have been replicated closely by the selected CMIP5 models forced by the historical condition, which provides an analogy of the interplay of three modes in the observed tropical Pacific SST.

  12. Frequency variations of discrete cranial traits in major human populations. II. Hypostotic variations

    PubMed Central

    HANIHARA, TSUNEHIKO; ISHIDA, HAJIME

    2001-01-01

    Five discrete hypostotic cranial traits, tympanic dehiscence, ovale-spinosum confluence, metopism, transverse zygomatic suture vestige, and biasterionic suture, were investigated in 81 human population samples. Except for ovale-spinosum confluence, marked asymmetric occurrences of the bilateral traits were not detected in the majority of the samples. Significant intertrait association was observed mainly between the biasterionic suture and other sutural variations including accessory ossicles. The traits showing relatively consistent sex differences across diverse populations were tympanic dehiscence, which is predominant in females, and biasterionic suture in males. On a world scale, the 5 hypostotic cranial traits showed distinctive patterns of geographical variation. Different clinal variations within and between macrogeographical areas such as western and eastern parts of the Old World were found for the frequencies of the traits. The Ainu may be the most distinct outlier in the eastern Asian region on the basis of the incidence of the traits, especially the transverse zygomatic suture vestige. The interregional variation without reasonable adaptive value and nonadaptive shift of the possible outliers presented in this study suggest that the genetic background for the occurrence of these traits cannot be excluded completely. PMID:11465863

  13. Tetrahydrobenzenes: Singlet-triplet separations and vibrational frequencies

    SciTech Connect

    Bettinger, H.F.; Schleyer, P.V.R.; Schaefer, H.F. III

    1999-03-31

    The energies and structures of the three tetradehydrobenzene (C{sub 6}H{sub 2}) isomers (ortho, meta, and para) were studied employing density functional theory (BLYP and B3LYP), complete active space SCF (CASSCF), and the coupled-cluster method with single, double (CCSD), and perturbative triple excitations [CCSD(T)] in conjunction with basis sets of up to triple-{zeta} plus double polarization quality. The meta isomer, 1,2,3,5-tetradehydrobenzene, is the most favorable cyclic isomer, but is 38 kcal mol{sup {minus}1} less stable than the hexatriyne C{sub 6}H{sub 2} global minimum. All of the cyclic isomers have singlet ground states, but these are less stable for the ortho and para isomers; hence, the singlet-triplet energy splittings for 1,2,4,5- and 1,2,3,4-tetradehydrobenzene are smaller than for ortho-benzyne. Harmonic vibrational frequency analyses [up to CCSD(T)/TZ2P] suggest that the {nu}{sub as}(C{triple{underscore}bond}C) vibration should be observable in the IR spectra of 1,2,4,5-tetradehydrobenzene at ca. 1,675 cm{sup {minus}1} but that this vibration might be too weak to be seen for 1,4-bis(trifluoromethyl)-2,3,5,6-tetradehydrobenzene.

  14. Read distance performance and variation of 5 low-frequency radio frequency identification panel transceiver manufacturers.

    PubMed

    Ryan, S E; Blasi, D A; Anglin, C O; Bryant, A M; Rickard, B A; Anderson, M P; Fike, K E

    2010-07-01

    Use of electronic animal identification technologies by livestock managers is increasing, but performance of these technologies can be variable when used in livestock production environments. This study was conducted to determine whether 1) read distance of low-frequency radio frequency identification (RFID) transceivers is affected by type of transponder being interrogated; 2) read distance variation of low-frequency RFID transceivers is affected by transceiver manufacturer; and 3) read distance of various transponder-transceiver manufacturer combinations meet the 2004 United States Animal Identification Plan (USAIP) bovine standards subcommittee minimum read distance recommendation of 60 cm. Twenty-four transceivers (n = 5 transceivers per manufacturer for Allflex, Boontech, Farnam, and Osborne; n = 4 transceivers for Destron Fearing) were tested with 60 transponders [n = 10 transponders per type for Allflex full duplex B (FDX-B), Allflex half duplex (HDX), Destron Fearing FDX-B, Farnam FDX-B, and Y-Tex FDX-B; n = 6 for Temple FDX-B (EM Microelectronic chip); and n = 4 for Temple FDX-B (HiTag chip)] presented in the parallel orientation. All transceivers and transponders met International Organization for Standardization 11784 and 11785 standards. Transponders represented both one-half duplex and full duplex low-frequency air interface technologies. Use of a mechanical trolley device enabled the transponders to be presented to the center of each transceiver at a constant rate, thereby reducing human error. Transponder and transceiver manufacturer interacted (P < 0.0001) to affect read distance, indicating that transceiver performance was greatly dependent upon the transponder type being interrogated. Twenty-eight of 30 combinations of transceivers and transponders evaluated met the minimum recommended USAIP read distance. The mean read distance across all 30 combinations was 45.1 to 129.4 cm. Transceiver manufacturer and transponder type interacted to affect read

  15. Frequency variations of discrete cranial traits in major human populations. III. Hyperostotic variations

    PubMed Central

    HANIHARA, TSUNEHIKO; ISHIDA, HAJIME

    2001-01-01

    Seven discrete cranial traits usually categorised as hyperostotic characters, the medial palatine canal, hypoglossal canal bridging, precondylar tubercle, condylus tertius, jugular foramen bridging, auditory exostosis, and mylohyoid bridging were investigated in 81 major human population samples from around the world. Significant asymmetric occurrences of the bilateral traits were detected in the medial palatine canal and jugular foramen bridging in several samples. Significant intertrait associations were found between some pairs of the traits, but not consistently across the large geographical samples. The auditory exostosis showed a predominant occurrence in males. With the exception of the auditory exostosis and mylohyoid bridging in a few samples, significant sex differences were slight. The frequency distributions of the traits (except for the auditory exostosis) showed some interregional clinality and intraregional discontinuity, suggesting that genetic drift could have contributed to the observed pattern of variation. PMID:11554504

  16. High frequency behavior of a rolling ball and simplification of the separation equation

    NASA Astrophysics Data System (ADS)

    Rutstam, Nils

    2013-05-01

    The Chaplygin separation equation for a rolling axisymmetric ball has an algebraic expression for the effective potential V ( z = cos θ, D, λ) that is difficult to analyze. We simplify this expression for the potential and find a 2-parameter family for when the potential becomes a rational function of z = cos θ. Then this separation equation becomes similar to the separation equation for the heavy symmetric top. For nutational solutions of a rolling sphere, we study a high frequency ω 3-dependence of the width of the nutational band, the depth of motion above V( z min, D, λ) and the ω 3-dependence of nutational frequency tfrac{{2π }} {T}.

  17. Time Variation of the Distance Separating Bomb and Dive Bomber Subsequent to Bomb Release

    NASA Technical Reports Server (NTRS)

    Mathews, Charles W.

    1952-01-01

    A study has been made of the variation of the distance separating bomb and aircraft with time after release as applied to dive-bombing operations, Separation distances determined from this study are presented in terms of two variables only, dive angle and maximum airplane accelerometer reading; the values of separation distance include the effects of delay in initiation of the pull-out and lag in attainment of the maximum normal acceleration.Contains analysis and calculations of the separation distances between bomb and dive bomber following bomb release, Separation distances as determined by the dive angle and the maximum airplane accelerometer reading are presented in a single chart.

  18. Are short-term variations in solar oscillation frequencies the signature of a second solar dynamo?

    NASA Astrophysics Data System (ADS)

    Broomhall, Anne-Marie; Fletcher, Stephen T.; Salabert, David; Basu, Sarbani; Chaplin, William J.; Elsworth, Yvonne; García, Rafael A.; Jiménez, Antonio; New, Roger

    2011-01-01

    In addition to the well-known 11-year solar cycle, the Sun's magnetic activity also shows significant variation on shorter time scales, e.g. between one and two years. We observe a quasi-biennial (2-year) signal in the solar p-mode oscillation frequencies, which are sensitive probes of the solar interior. The signal is visible in Sun-as-a-star data observed by different instruments and here we describe the results obtained using BiSON, GOLF, and VIRGO data. Our results imply that the 2-year signal is susceptible to the influence of the main 11-year solar cycle. However, the source of the signal appears to be separate from that of the 11-year cycle. We speculate as to whether it might be the signature of a second dynamo, located in the region of near-surface rotational shear.

  19. Variation in the Input: A Case Study of Manner Class Frequencies

    ERIC Educational Resources Information Center

    Daland, Robert

    2013-01-01

    What are the sources of variation in the input, and how much do they matter for language acquisition? This study examines frequency variation in manner-of-articulation classes in child and adult input. The null hypothesis is that segmental frequency distributions of language varieties are unigram (modelable by stationary, ergodic processes), and…

  20. Spatial pattern separation of chemicals and frequency-independent components by terahertz spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Watanabe, Yuuki; Kawase, Kodo; Ikari, Tomofumi; Ito, Hiromasa; Ishikawa, Youichi; Minamide, Hiroaki

    2003-10-01

    We separated the component spatial patterns of frequency-dependent absorption in chemicals and frequency-independent components such as plastic, paper, and measurement noise in terahertz (THz) spectroscopic images, using known spectral curves. Our measurement system, which uses a widely tunable coherent THz-wave parametric oscillator source, can image at a specific frequency in the range 1-2 THz. The component patterns of chemicals can easily be extracted by use of the frequency-independent components. This method could be successfully used for nondestructive inspection for the detection of illegal drugs and devices of bioterrorism concealed, e.g., inside mail and packages.

  1. Frequency variations of solar radio zebras and their power-law spectra

    NASA Astrophysics Data System (ADS)

    Karlický, M.

    2014-01-01

    Context. During solar flares several types of radio bursts are observed. The fine striped structures of the type IV solar radio bursts are called zebras. Analyzing them provides important information about the plasma parameters of their radio sources. We present a new analysis of zebras. Aims: Power spectra of the frequency variations of zebras are computed to estimate the spectra of the plasma density variations in radio zebra sources. Methods: Frequency variations of zebra lines and the high-frequency boundary of the whole radio burst were determined with and without the frequency fitting. The computed time dependencies of these variations were analyzed with the Fourier method. Results: First, we computed the variation spectrum of the high-frequency boundary of the whole radio burst, which is composed of several zebra patterns. This power spectrum has a power-law form with a power-law index -1.65. Then, we selected three well-defined zebra-lines in three different zebra patterns and computed the spectra of their frequency variations. The power-law indices in these cases are found to be in the interval between -1.61 and -1.75. Finally, assuming that the zebra-line frequency is generated on the upper-hybrid frequency and that the plasma frequency ωpe is much higher than the electron-cyclotron frequency ωce, the Fourier power spectra are interpreted to be those of the electron plasma density in zebra radio sources.

  2. Separation of overlapping linear frequency modulated (LFM) signals using the fractional fourier transform.

    PubMed

    Cowell, David M J; Freear, Steven

    2010-10-01

    Linear frequency modulated (LFM) excitation combined with pulse compression provides an increase in SNR at the receiver. LFM signals are of longer duration than pulsed signals of the same bandwidth; consequently, in many practical situations, maintaining temporal separation between echoes is not possible. Where analysis is performed on individual LFM signals, a separation technique is required. Time windowing is unable to separate signals overlapping in time. Frequency domain filtering is unable to separate signals with overlapping spectra. This paper describes a method to separate time-overlapping LFM signals through the application of the fractional Fourier transform (FrFT), a transform operating in both time and frequency domains. A short introduction to the FrFT and its operation and calculation are presented. The proposed signal separation method is illustrated by application to a simulated ultrasound signal, created by the summation of multiple time-overlapping LFM signals and the component signals recovered with ±0.6% spectral error. The results of an experimental investigation are presented in which the proposed separation method is applied to time-overlapping LFM signals created by the transmission of a LFM signal through a stainless steel plate and water-filled pipe.

  3. How to separate the low amplitude delta Scuti variation in CoRoT data unambigousely?

    NASA Astrophysics Data System (ADS)

    Benko, Jozsef M.; Paparo, Margit

    2015-08-01

    Rich regular frequency patterns were found in the Fourier spectra of low-amplitude Delta Scuti stars observed by CoRoT satellite. The CoRoT observations are, however, influenced by the disturbing effect of the SAA. The effect is marginal for high amplitude variable stars but it could be dangerous in the case of low amplitude variables, especially if the frequency range of the intrinsic variation overlaps the instrumental frequencies. Systematic tests were carried out both on synthetic and real data. Our aim was to determine a limit amplitude above which we were sure that the frequency pattern belonged to the stars.

  4. Determinants of echolocation call frequency variation in the Formosan lesser horseshoe bat (Rhinolophus monoceros)

    PubMed Central

    Chen, Shiang-Fan; Jones, Gareth; Rossiter, Stephen J.

    2009-01-01

    The origin and maintenance of intraspecific variation in vocal signals is important for population divergence and speciation. Where vocalizations are transmitted by vertical cultural inheritance, similarity will reflect co-ancestry, and thus vocal divergence should reflect genetic structure. Horseshoe bats are characterized by echolocation calls dominated by a constant frequency component that is partly determined by maternal imprinting. Although previous studies showed that constant frequency calls are also influenced by some non-genetic factors, it is not known how frequency relates to genetic structure. To test this, we related constant frequency variation to genetic and non-genetic variables in the Formosan lesser horseshoe bat (Rhinolophus monoceros). Recordings of bats from across Taiwan revealed that females called at higher frequencies than males; however, we found no effect of environmental or morphological factors on call frequency. By comparison, variation showed clear population structure, with frequencies lower in the centre and east, and higher in the north and south. Within these regions, frequency divergence was directional and correlated with geographical distance, suggesting that call frequencies are subject to cultural drift. However, microsatellite clustering analysis showed that broad differences in constant frequency among populations corresponded to discontinuities in allele frequencies resulting from vicariant events. Our results provide evidence that the processes shaping genetic subdivision have concomitant consequences for divergence in echolocation call frequency. PMID:19692399

  5. High Frequency Variations in Earth Orientation Derived From GNSS Observations

    NASA Astrophysics Data System (ADS)

    Weber, R.; Englich, S.; Snajdrova, K.; Boehm, J.

    2006-12-01

    Current observations gained by the space geodetic techniques, especially VLBI, GPS and SLR, allow for the determination of Earth Orientation Parameters (EOPs - polar motion, UT1/LOD, nutation offsets) with unprecedented accuracy and temporal resolution. This presentation focuses on contributions to the EOP recovery provided by satellite navigation systems (primarily GPS). The IGS (International GNSS Service), for example, currently provides daily polar motion with an accuracy of less than 0.1mas and LOD estimates with an accuracy of a few microseconds. To study more rapid variations in polar motion and LOD we established in a first step a high resolution (hourly resolution) ERP-time series from GPS observation data of the IGS network covering the period from begin of 2005 till March 2006. The calculations were carried out by means of the Bernese GPS Software V5.0 considering observations from a subset of 79 fairly stable stations out of the IGb00 reference frame sites. From these ERP time series the amplitudes of the major diurnal and semidiurnal variations caused by ocean tides are estimated. After correcting the series for ocean tides the remaining geodetic observed excitation is compared with variations of atmospheric excitation (AAM). To study the sensitivity of the estimates with respect to the applied mapping function we applied both the widely used NMF (Niell Mapping Function) and the VMF1 (Vienna Mapping Function 1). In addition, based on computations covering two months in 2005, the potential improvement due to the use of additional GLONASS data will be discussed. Finally, satellite techniques are also able to provide nutation offset rates with respect to the most recent nutation model. Based on GPS observations from 2005 we established nutation rate time series and subsequently derived the amplitudes of several nutation waves with periods less than 30 days. The results are compared to VLBI estimates processed by means of the OCCAM 6.1 software.

  6. Convolution-variation separation method for efficient modeling of optical lithography.

    PubMed

    Liu, Shiyuan; Zhou, Xinjiang; Lv, Wen; Xu, Shuang; Wei, Haiqing

    2013-07-01

    We propose a general method called convolution-variation separation (CVS) to enable efficient optical imaging calculations without sacrificing accuracy when simulating images for a wide range of process variations. The CVS method is derived from first principles using a series expansion, which consists of a set of predetermined basis functions weighted by a set of predetermined expansion coefficients. The basis functions are independent of the process variations and thus may be computed and stored in advance, while the expansion coefficients depend only on the process variations. Optical image simulations for defocus and aberration variations with applications in robust inverse lithography technology and lens aberration metrology have demonstrated the main concept of the CVS method.

  7. Wide Angle, Single Screen, Gridded Square-Loop Frequency Selective Surface for Diplexing Two Closely Separated Frequency Bands

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao (Inventor)

    1996-01-01

    The design and performance of a wide angle, single screen, frequency selective surface (FSS) with gridded square-loop path elements are described for diplexing closely separated signal bands, for example, X- and Ku-band signals in an Orbiting Very Long Baseline Interferometer (OVLBI) earth station reflector antenna system, as well as other applications such as military and commercial communications via satellites. Excellent agreement is obtained between the predicted and measured results of this FSS design using the gridded square-loop patch elements sandwiched between 0.0889 cm thick tetrafluoroethylene fluorocarbon polymer (PTFE) slabs. Resonant frequency drift is reduced by 1 GHz with an incidence angle from 0 deg normal to 40 deg from normal.

  8. Silent (painless) thyroiditis. Evidence of a geographic variation in frequency

    SciTech Connect

    Vitug, A.C.; Goldman, J.M.

    1985-03-01

    Recent reports suggest that 14% to 23% of thyrotoxic patients have silent (painless) thyroiditis, a newly described syndrome characterized by transient thyrotoxicosis with a low radioactive iodine uptake. A three-year review at a Brooklyn (NY) hospital showed only one definite and three possible cases of silent thyroiditis among 86 thyrotoxic patients. At most, 4% to 5% of thyrotoxic patients had silent thyroiditis. The authors suggest a geographic variation in this syndrome. Most cases and the largest series are from Japan and the Great Lakes area of North America. The latter may be related to increased iodine intake over many years in a previously endemic area of hypoiodidism and goiter, although other local factors may also be involved.

  9. A frequency-control particle separation device based on resultant effects of electroosmosis and dielectrophoresis

    NASA Astrophysics Data System (ADS)

    Lin, Shiang-Chi; Tung, Yi-Chung; Lin, Chih-Ting

    2016-08-01

    Particle separation plays an important role in microfluidic sample preparation for various biomedical applications. In this paper, we report a particle manipulation and separation scheme using a microfluidic device based on low-volume/low-voltage electrokinetic frequency modulation. Utilizing a circular micro-electrode array, both electroosmosis and dielectrophoresis can be contributed to manipulate particles in the device by controlling the frequency of applied sinusoidal travelling wave signals. Theoretical simulations based on finite-element methods are employed to establish fundamental understanding of the developed scheme. For experimental demonstration, polystyrene beads (6 μm in diameter) and human promyelocytic leukaemia cells (HL-60) are used to validate the frequency-modulation effect. Furthermore, different diameter polystyrene beads (6 μm and 10 μm in diameter) are mixed to show potentials of precise particle separations (˜90% efficiency) by the reported frequency-controlled electrokinetic device. The developed technique can be exploited as an actuation scheme and particle manipulation method for microfluidic sample preparations of low ionic concentration samples.

  10. Separation of experimental 2D IR frequency-frequency correlation functions into structural and reorientation-induced contributions

    NASA Astrophysics Data System (ADS)

    Kramer, Patrick L.; Nishida, Jun; Fayer, Michael D.

    2015-09-01

    A vibrational transition frequency can couple to its environment through a directional vector interaction. In such cases, reorientation of the vibrational transition dipole (molecular orientational relaxation) and its frequency fluctuations can be strongly coupled. It was recently shown [Kramer et al., J. Chem. Phys. 142, 184505 (2015)] that differing frequency-frequency correlation function (FFCF) decays, due to reorientation-induced spectral diffusion (RISD), are observed with different two-dimensional infrared polarization configurations when such strong coupling is present. The FFC functional forms were derived for the situation in which all spectral diffusion is due to reorientational motion. We extend the previous theory to include vibrational frequency evolution (spectral diffusion) caused by structural fluctuations of the medium. Model systems with diffusive reorientation and several regimes of structural spectral diffusion rates are analyzed for first order Stark effect interactions. Additionally, the transition dipole reorientational motion in complex environments is frequently not completely diffusive. Several periods of restricted angular motion (wobbling-in-a-cone) may precede the final diffusive orientational randomization. The polarization-weighted FFCF decays are presented in this case of restricted transition dipole wobbling. With these extensions to the polarization-dependent FFCF expressions, the structural spectral diffusion dynamics of methanol in the room temperature ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate can be separated quantitatively from RISD using the experimental center line slope data. In addition, prior results on the spectral diffusion of water, methanol, and ethanol in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide are re-examined to elucidate the influence of reorientation on the data, which were interpreted in terms of structural fluctuations.

  11. Variation in the resting frequency of Rhinolophus pusillus in Mainland China: effect of climate and implications for conservation.

    PubMed

    Jiang, Tinglei; Metzner, Walter; You, Yuyan; Liu, Sen; Lu, Guanjun; Li, Shi; Wang, Lei; Feng, Jiang

    2010-10-01

    This study describes variation patterns in the constant frequency of echolocation calls emitted at rest and when not flying ("resting frequency" RF) of the least horseshoe bat, Rhinolophus pusillus, on a broad geographical scale and in response to local climatic variables. Significant differences in RF were observed among populations throughout the species range in Mainland China, and this variation was positively and significantly related to climate conditions, especially environmental humidity, but the variability was only weakly associated with geographical distance. Sex dimorphism in the RF of R. pusillus may imply that female and male might keep their frequencies within a narrow range for sex recognition. Moreover, bats adjusted resting frequency to humidity, which may imply partitioning diet by prey size or the influence of rainfall noise. The results indicate that bats adjust echolocation call frequency to adapt to environmental conditions. Therefore, environmental selection shape the diversity of echolocation call structure of R. pusillus in geographically separated populations, and conservation efforts should focus on changes in local climate and effects of environmental noise.

  12. Separation of Intercepted Multi-Radar Signals Based on Parameterized Time-Frequency Analysis

    NASA Astrophysics Data System (ADS)

    Lu, W. L.; Xie, J. W.; Wang, H. M.; Sheng, C.

    2016-09-01

    Modern radars use complex waveforms to obtain high detection performance and low probabilities of interception and identification. Signals intercepted from multiple radars overlap considerably in both the time and frequency domains and are difficult to separate with primary time parameters. Time-frequency analysis (TFA), as a key signal-processing tool, can provide better insight into the signal than conventional methods. In particular, among the various types of TFA, parameterized time-frequency analysis (PTFA) has shown great potential to investigate the time-frequency features of such non-stationary signals. In this paper, we propose a procedure for PTFA to separate overlapped radar signals; it includes five steps: initiation, parameterized time-frequency analysis, demodulating the signal of interest, adaptive filtering and recovering the signal. The effectiveness of the method was verified with simulated data and an intercepted radar signal received in a microwave laboratory. The results show that the proposed method has good performance and has potential in electronic reconnaissance applications, such as electronic intelligence, electronic warfare support measures, and radar warning.

  13. Aero-acoustics source separation with sparsity inducing priors in the frequency domain

    NASA Astrophysics Data System (ADS)

    Schwander, Olivier; Picheral, José; Gac, Nicolas; Mohammad-Djafari, Ali; Blacodon, Daniel

    2015-01-01

    The characterization of acoustic sources is of great interest in many industrial applications, in particular for the aeronautic or automotive industry for the development of new products. While localization of sources using observations from a wind tunnel is a well-known subject, the characterization and separation of the sources still needs to be explored. We present here a Bayesian approach for sources separation. Two prior modeling of the sources are considered: a sparsity inducing prior in the frequency domain and an autoregressive model in the time domain. The proposed methods are evaluated on synthetic data simulating noise sources emitting from an airfoil inside a wind tunnel.

  14. Variation in the resting frequency of Rhinolophus pusillus in Mainland China: Effect of climate and implications for conservation

    PubMed Central

    Jiang, Tinglei; Metzner, Walter; You, Yuyan; Liu, Sen; Lu, Guanjun; Li, Shi; Wang, Lei; Feng, Jiang

    2010-01-01

    This study describes variation patterns in the constant frequency of echolocation calls emitted at rest and when not flying (“resting frequency” RF) of the least horseshoe bat, Rhinolophus pusillus, on a broad geographical scale and in response to local climatic variables. Significant differences in RF were observed among populations throughout the species range in Mainland China, and this variation was positively and significantly related to climate conditions, especially environmental humidity, but the variability was only weakly associated with geographical distance. Sex dimorphism in the RF of R. pusillus may imply that female and male might keep their frequencies within a narrow range for sex recognition. Moreover, bats adjusted resting frequency to humidity, which may imply partitioning diet by prey size or the influence of rainfall noise. The results indicate that bats adjust echolocation call frequency to adapt to environmental conditions. Therefore, environmental selection shape the diversity of echolocation call structure of R. pusillus in geographically separated populations, and conservation efforts should focus on changes in local climate and effects of environmental noise. PMID:20968390

  15. Underdetermined Blind Source Separation with Variational Mode Decomposition for Compound Roller Bearing Fault Signals.

    PubMed

    Tang, Gang; Luo, Ganggang; Zhang, Weihua; Yang, Caijin; Wang, Huaqing

    2016-01-01

    In the condition monitoring of roller bearings, the measured signals are often compounded due to the unknown multi-vibration sources and complex transfer paths. Moreover, the sensors are limited in particular locations and numbers. Thus, this is a problem of underdetermined blind source separation for the vibration sources estimation, which makes it difficult to extract fault features exactly by ordinary methods in running tests. To improve the effectiveness of compound fault diagnosis in roller bearings, the present paper proposes a new method to solve the underdetermined problem and to extract fault features based on variational mode decomposition. In order to surmount the shortcomings of inadequate signals collected through limited sensors, a vibration signal is firstly decomposed into a number of band-limited intrinsic mode functions by variational mode decomposition. Then, the demodulated signal with the Hilbert transform of these multi-channel functions is used as the input matrix for independent component analysis. Finally, the compound faults are separated effectively by carrying out independent component analysis, which enables the fault features to be extracted more easily and identified more clearly. Experimental results validate the effectiveness of the proposed method in compound fault separation, and a comparison experiment shows that the proposed method has higher adaptability and practicability in separating strong noise signals than the commonly-used ensemble empirical mode decomposition method. PMID:27322268

  16. Underdetermined Blind Source Separation with Variational Mode Decomposition for Compound Roller Bearing Fault Signals.

    PubMed

    Tang, Gang; Luo, Ganggang; Zhang, Weihua; Yang, Caijin; Wang, Huaqing

    2016-06-16

    In the condition monitoring of roller bearings, the measured signals are often compounded due to the unknown multi-vibration sources and complex transfer paths. Moreover, the sensors are limited in particular locations and numbers. Thus, this is a problem of underdetermined blind source separation for the vibration sources estimation, which makes it difficult to extract fault features exactly by ordinary methods in running tests. To improve the effectiveness of compound fault diagnosis in roller bearings, the present paper proposes a new method to solve the underdetermined problem and to extract fault features based on variational mode decomposition. In order to surmount the shortcomings of inadequate signals collected through limited sensors, a vibration signal is firstly decomposed into a number of band-limited intrinsic mode functions by variational mode decomposition. Then, the demodulated signal with the Hilbert transform of these multi-channel functions is used as the input matrix for independent component analysis. Finally, the compound faults are separated effectively by carrying out independent component analysis, which enables the fault features to be extracted more easily and identified more clearly. Experimental results validate the effectiveness of the proposed method in compound fault separation, and a comparison experiment shows that the proposed method has higher adaptability and practicability in separating strong noise signals than the commonly-used ensemble empirical mode decomposition method.

  17. Underdetermined Blind Source Separation with Variational Mode Decomposition for Compound Roller Bearing Fault Signals

    PubMed Central

    Tang, Gang; Luo, Ganggang; Zhang, Weihua; Yang, Caijin; Wang, Huaqing

    2016-01-01

    In the condition monitoring of roller bearings, the measured signals are often compounded due to the unknown multi-vibration sources and complex transfer paths. Moreover, the sensors are limited in particular locations and numbers. Thus, this is a problem of underdetermined blind source separation for the vibration sources estimation, which makes it difficult to extract fault features exactly by ordinary methods in running tests. To improve the effectiveness of compound fault diagnosis in roller bearings, the present paper proposes a new method to solve the underdetermined problem and to extract fault features based on variational mode decomposition. In order to surmount the shortcomings of inadequate signals collected through limited sensors, a vibration signal is firstly decomposed into a number of band-limited intrinsic mode functions by variational mode decomposition. Then, the demodulated signal with the Hilbert transform of these multi-channel functions is used as the input matrix for independent component analysis. Finally, the compound faults are separated effectively by carrying out independent component analysis, which enables the fault features to be extracted more easily and identified more clearly. Experimental results validate the effectiveness of the proposed method in compound fault separation, and a comparison experiment shows that the proposed method has higher adaptability and practicability in separating strong noise signals than the commonly-used ensemble empirical mode decomposition method. PMID:27322268

  18. High Contrast Imaging with Spitzer: Constraining the Frequency of Giant Planets out to 1000 au Separations

    NASA Astrophysics Data System (ADS)

    Durkan, Stephen; Janson, Markus; Carson, Joseph C.

    2016-06-01

    We report results of a re-analysis of archival Spitzer IRAC direct imaging surveys encompassing a variety of nearby stars. Our sample is generated from the combined observations of 73 young stars (median age, distance, spectral type = 85 Myr, 23.3 pc, G5) and 48 known exoplanet host stars with unconstrained ages (median distance, spectral type = 22.6 pc, G5). While the small size of Spitzer provides a lower resolution than 8 m class AO-assisted ground-based telescopes, which have been used for constraining the frequency of 0.5–13 M J planets at separations of 10–102 au, its exquisite infrared sensitivity provides the ability to place unmatched constraints on the planetary populations at wider separations. Here we apply sophisticated high-contrast techniques to our sample in order to remove the stellar point-spread function and to open up sensitivity to planetary mass companions down to 5″ separations. This enables sensitivity to 0.5–13 M J planets at physical separations on the order of 102–103 au, allowing us to probe a parameter space that has not previously been systematically explored to any similar degree of sensitivity. Based on a color and proper motion analysis, we do not record any planetary detections. Exploiting this enhanced survey sensitivity, employing Monte Carlo simulations with a Bayesian approach, and assuming a mass distribution of {dn}/{dm}\\propto {m}-1.31, we constrain (at 95% confidence) a population of 0.5–13 M J planets at separations of 100–1000 au with an upper frequency limit of 9%.

  19. High Contrast Imaging with Spitzer: Constraining the Frequency of Giant Planets out to 1000 au Separations

    NASA Astrophysics Data System (ADS)

    Durkan, Stephen; Janson, Markus; Carson, Joseph C.

    2016-06-01

    We report results of a re-analysis of archival Spitzer IRAC direct imaging surveys encompassing a variety of nearby stars. Our sample is generated from the combined observations of 73 young stars (median age, distance, spectral type = 85 Myr, 23.3 pc, G5) and 48 known exoplanet host stars with unconstrained ages (median distance, spectral type = 22.6 pc, G5). While the small size of Spitzer provides a lower resolution than 8 m class AO-assisted ground-based telescopes, which have been used for constraining the frequency of 0.5-13 M J planets at separations of 10-102 au, its exquisite infrared sensitivity provides the ability to place unmatched constraints on the planetary populations at wider separations. Here we apply sophisticated high-contrast techniques to our sample in order to remove the stellar point-spread function and to open up sensitivity to planetary mass companions down to 5″ separations. This enables sensitivity to 0.5-13 M J planets at physical separations on the order of 102-103 au, allowing us to probe a parameter space that has not previously been systematically explored to any similar degree of sensitivity. Based on a color and proper motion analysis, we do not record any planetary detections. Exploiting this enhanced survey sensitivity, employing Monte Carlo simulations with a Bayesian approach, and assuming a mass distribution of {dn}/{dm}\\propto {m}-1.31, we constrain (at 95% confidence) a population of 0.5-13 M J planets at separations of 100-1000 au with an upper frequency limit of 9%.

  20. System identification through nonstationary data using Time-Frequency Blind Source Separation

    NASA Astrophysics Data System (ADS)

    Guo, Yanlin; Kareem, Ahsan

    2016-06-01

    Classical output-only system identification (SI) methods are based on the assumption of stationarity of the system response. However, measured response of buildings and bridges is usually non-stationary due to strong winds (e.g. typhoon, and thunder storm etc.), earthquakes and time-varying vehicle motions. Accordingly, the response data may have time-varying frequency contents and/or overlapping of modal frequencies due to non-stationary colored excitation. This renders traditional methods problematic for modal separation and identification. To address these challenges, a new SI technique based on Time-Frequency Blind Source Separation (TFBSS) is proposed. By selectively utilizing "effective" information in local regions of the time-frequency plane, where only one mode contributes to energy, the proposed technique can successfully identify mode shapes and recover modal responses from the non-stationary response where the traditional SI methods often encounter difficulties. This technique can also handle response with closely spaced modes which is a well-known challenge for the identification of large-scale structures. Based on the separated modal responses, frequency and damping can be easily identified using SI methods based on a single degree of freedom (SDOF) system. In addition to the exclusive advantage of handling non-stationary data and closely spaced modes, the proposed technique also benefits from the absence of the end effects and low sensitivity to noise in modal separation. The efficacy of the proposed technique is demonstrated using several simulation based studies, and compared to the popular Second-Order Blind Identification (SOBI) scheme. It is also noted that even some non-stationary response data can be analyzed by the stationary method SOBI. This paper also delineates non-stationary cases where SOBI and the proposed scheme perform comparably and highlights cases where the proposed approach is more advantageous. Finally, the performance of the

  1. Separating Reflective and Fluorescent Components Using High Frequency Illumination in the Spectral Domain.

    PubMed

    Fu, Ying; Lam, Antony; Sato, Imari; Okabe, Takahiro; Sato, Yoichi

    2016-05-01

    Hyperspectral imaging is beneficial to many applications but most traditional methods do not consider fluorescent effects which are present in everyday items ranging from paper to even our food. Furthermore, everyday fluorescent items exhibit a mix of reflection and fluorescence so proper separation of these components is necessary for analyzing them. In recent years, effective imaging methods have been proposed but most require capturing the scene under multiple illuminants. In this paper, we demonstrate efficient separation and recovery of reflectance and fluorescence emission spectra through the use of two high frequency illuminations in the spectral domain. With the obtained fluorescence emission spectra from our high frequency illuminants, we then describe how to estimate the fluorescence absorption spectrum of a material given its emission spectrum. In addition, we provide an in depth analysis of our method and also show that filters can be used in conjunction with standard light sources to generate the required high frequency illuminants. We also test our method under ambient light and demonstrate an application of our method to synthetic relighting of real scenes. PMID:26336113

  2. Collective frequency variation in network synchronization and reverse PageRank

    NASA Astrophysics Data System (ADS)

    Skardal, Per Sebastian; Taylor, Dane; Sun, Jie; Arenas, Alex

    2016-04-01

    A wide range of natural and engineered phenomena rely on large networks of interacting units to reach a dynamical consensus state where the system collectively operates. Here we study the dynamics of self-organizing systems and show that for generic directed networks the collective frequency of the ensemble is not the same as the mean of the individuals' natural frequencies. Specifically, we show that the collective frequency equals a weighted average of the natural frequencies, where the weights are given by an outflow centrality measure that is equivalent to a reverse PageRank centrality. Our findings uncover an intricate dependence of the collective frequency on both the structural directedness and dynamical heterogeneity of the network, and also reveal an unexplored connection between synchronization and PageRank, which opens the possibility of applying PageRank optimization to synchronization. Finally, we demonstrate the presence of collective frequency variation in real-world networks by considering the UK and Scandinavian power grids.

  3. Frequency variations of discrete cranial traits in major human populations. IV. Vessel and nerve related variations

    PubMed Central

    HANIHARA, TSUNEHIKO; ISHIDA, HAJIME

    2001-01-01

    This concludes a series of descriptive statistical reports on discrete cranial traits in 81 human populations from around the world. Four variants classified as vessel and nerve related characters were investigated: patent condylar canal; supraorbital foramen; accessory infraorbital foramen; and accessory mental foramen. A significant asymmetric occurrence without any side preference was detected for the accessory mental foramen. Significant intertrait associations were found between the accessory infraorbital and supraorbital foramina in the panPacific region and Subsaharan African samples. The intertrait associations between the accessory infraorbital foramen and some traits classified as hypostotic were found mainly in the samples from the western part of the Old World, and those as hyperostotic traits in the samples from eastern Asian and the related population samples. With a few exceptions, the occurrence of a patent condylar canal and a supraorbital foramen was predominant in females, but the accessory infraorbital and accessory mental foramina were predominant in males. The frequency distributions of the traits showed interregional clinality and intraregional discontinuity. A temporal trend was found in the Northeast Asian region in the frequencies of the accessory infraorbital and accessory mental foramina. The diversity of modern human discrete cranial traits may at least in part be attributable to differential retention or intensification from an ancestral pattern. PMID:11554505

  4. Frequency of radial artery anatomic variations in patients undergoing transradial heart catheterization.

    PubMed

    Ostojić, Zvonimir; Bulum, Joško; Ernst, Aleksander; Strozzi, Maja; Marić-Bešić, Kristina

    2015-03-01

    Over the last ten years, transradial cardiac catheterization has been increasingly applied, primarily because of its lower incidence of complications compared to the femoral approach. However, one of the greatest flaws of the transradial approach is a relatively high incidence of catheterization failure (1%-5%). Anatomic variations of radial artery are ranked second among the reasons for this. Previous studies have not provided unambiguous data on the frequency of these anomalies. It was therefore the aim of this study to determine the frequency of anatomic variations using routine angiographies of radial artery during left heart catheterization. This was a retrospective study involving examination of 602 images of routine angiographies of radial artery performed during cardiac catheterization. The frequency of anatomic variations of radial artery was 8.8%, exclusive of tortuosities with a frequency of 12.7%. The most frequent anatomic variation was the high origin of radial artery, found in 31 (5.1%) subjects. Radioulnar loops, being one of the potential contraindications for the procedure, were reported in 2% of cases. Regression analysis revealed that age (p < 0.001), female sex (p = 0.015) and high origin (p = 0.034) considerably contributed to the development of tortuosity. The results indicated the incidence of tortuosity to increase linearly with age. Although it is not a contraindication for continuing with the procedure, we recommend that elderly patients have angiography of radial artery performed at the beginning of the procedure due to the higher frequency of tortuosity. PMID:26058245

  5. Low-Frequency Flow Oscillations on Stalled Wings Exhibiting Cellular Separation Topology

    NASA Astrophysics Data System (ADS)

    Disotell, Kevin James

    One of the most pervasive threats to aircraft controllability is wing stall, a condition associated with loss of lift due to separation of air flow from the wing surface at high angles of attack. A recognized need for improved upset recovery training in extended-envelope flight simulators is a physical understanding of the post-stall aerodynamic environment, particularly key flow phenomena which influence the vehicle trajectory. Large-scale flow structures known as stall cells, which scale with the wing chord and are spatially-periodic along the span, have been previously observed on post-stall airfoils with trailing-edge separation present. Despite extensive documentation of stall cells in the literature, the physical mechanisms behind their formation and evolution have proven to be elusive. The undertaken study has sought to characterize the inherently turbulent separated flow existing above the wing surface with cell formation present. In particular, the question of how the unsteady separated flow may interact with the wing to produce time-averaged cellular surface patterns is considered. Time-resolved, two-component particle image velocimetry measurements were acquired at the plane of symmetry of a single stall cell formed on an extruded NACA 0015 airfoil model at chord Reynolds number of 560,000 to obtain insight into the time-dependent flow structure. The evolution of flow unsteadiness was analyzed over a static angle-of-attack range covering the narrow post-stall regime in which stall cells have been observed. Spectral analysis of velocity fields acquired near the stall angle confirmed a low-frequency flow oscillation previously detected in pointwise surface measurements by Yon and Katz (1998), corresponding to a Strouhal number of 0.042 based on frontal projected chord height. Probability density functions of the streamwise velocity component were used to estimate the convective speed of this mode at approximately half the free-stream velocity, in agreement

  6. Observation of a 100-MHz frequency variation across the output of a frequency-doubled injection-seeded unstable-resonator Q-switched Nd:YAG laser.

    PubMed

    Forkey, J N; Lempert, W R; Miles, R B

    1997-02-15

    We report high-resolution measurements of the spatial variation of the optical frequency of an injection-seeded unstable-resonator Q-switched Nd:YAG laser. Images of the second harmonic taken through a molecular-iodine notch filter show frequency variations of as much as 100 MHz (second harmonic) between the center and the edge of the beam. PMID:18183159

  7. Negative frequency-dependent preferences and variation in male facial hair.

    PubMed

    Janif, Zinnia J; Brooks, Robert C; Dixson, Barnaby J

    2014-01-01

    Negative frequency-dependent sexual selection maintains striking polymorphisms in secondary sexual traits in several animal species. Here, we test whether frequency of beardedness modulates perceived attractiveness of men's facial hair, a secondary sexual trait subject to considerable cultural variation. We first showed participants a suite of faces, within which we manipulated the frequency of beard thicknesses and then measured preferences for four standard levels of beardedness. Women and men judged heavy stubble and full beards more attractive when presented in treatments where beards were rare than when they were common, with intermediate preferences when intermediate frequencies of beardedness were presented. Likewise, clean-shaven faces were least attractive when clean-shaven faces were most common and more attractive when rare. This pattern in preferences is consistent with negative frequency-dependent selection.

  8. Variables separation of the spectral BRDF for better understanding color variation in special effect pigment coatings.

    PubMed

    Ferrero, Alejandro; Rabal, Ana María; Campos, Joaquín; Pons, Alicia; Hernanz, María Luisa

    2012-06-01

    A type of representation of the spectral bidirectional reflectance distribution function (BRDF) is proposed that distinctly separates the spectral variable (wavelength) from the geometrical variables (spherical coordinates of the irradiation and viewing directions). Principal components analysis (PCA) is used in order to decompose the spectral BRDF in decorrelated spectral components, and the weight that they have at every geometrical configuration of irradiation/viewing is established. This method was applied to the spectral BRDF measurement of a special effect pigment sample, and four principal components with relevant variance were identified. These four components are enough to reproduce the great diversity of spectral reflectances observed at different geometrical configurations. Since this representation is able to separate spectral and geometrical variables, it facilitates the interpretation of the color variation of special effect pigments coatings versus the geometrical configuration of irradiation/viewing.

  9. Sensitivity of Conditional-Discrimination Performance to Within-Session Variation of Reinforcer Frequency

    ERIC Educational Resources Information Center

    Ward, Ryan D.; Odum, Amy L.

    2008-01-01

    The present experiment developed a methodology for assessing sensitivity of conditional-discrimination performance to within-session variation of reinforcer frequency. Four pigeons responded under a multiple schedule of matching-to-sample components in which the ratio of reinforcers for correct S[subscript 1] and S[subscript 2] responses was…

  10. Fundamental Frequency Variation with an Electrolarynx Improves Speech Understanding: A Case Study

    ERIC Educational Resources Information Center

    Watson, Peter J.; Schlauch, Robert S.

    2009-01-01

    Purpose: This study examined the effect of fundamental frequency (F0) variation on the intelligibility of speech in an alaryngeal talker who used an electrolarynx (EL). Method: One experienced alaryngeal talker produced variable F0 and a constant F0 with his EL as he read sentences aloud. As a control, a group of sentences with variable F0 was…

  11. Separation of fine particles at different frequencies and HRTs using acoustic standing waves.

    PubMed

    Ahn, Kwang Ho; Ahn, Jaehwan; Kim, I-Tae; Kang, Sungwon; Kim, Seoggu; Chu, Kyoung Hoon; Ko, Kwang Baik

    2015-01-01

    The objective of this study was to evaluate the separation of fine particles using several frequencies and hydraulic retention times (HRTs) in an acoustic standing wave reactor without any separate cooling devices. The acoustic standing wave reactor consisted of sufficient space (over 100 mm) between the transducer and reflector, resulting in a slight increase in temperature. However, the increase in temperature did not affect the formation of standing waves and particle aggregations in our experiments. The results indicated that the turbidity removal efficiencies of fine kaolin particles, when using frequencies of 580 kHz, 1, and 2 MHz, increased with longer standing wave operation time. Especially, the turbidity removal efficiencies for 1 and 2 MHz were higher than that for 580 kHz because the wavelength (λ) of the 580 kHz wave was longer than that of the 1 and 2 MHz waves. Furthermore, the turbidity removal efficiency of kaolin in a continuous reactor improved with increasing hydraulic retention times (HRTs), and the reactor was more effective with 1 and 2 MHz used in parallel instead of 1 and 2 MHz used individually under the same HRT conditions with the entrance length (EL) having no adverse effect.

  12. Separating cognitive processes with principal components analysis of EEG time-frequency distributions

    NASA Astrophysics Data System (ADS)

    Bernat, Edward M.; Nelson, Lindsay D.; Holroyd, Clay B.; Gehring, William J.; Patrick, Christopher J.

    2008-08-01

    Measurement of EEG event-related potential (ERP) data has been most commonly undertaken in the time-domain, which can be complicated to interpret when separable activity overlaps in time. When the overlapping activity has distinct frequency characteristics, however, time-frequency (TF) signal processing techniques can be useful. The current report utilized ERP data from a cognitive task producing typical feedback-related negativity (FRN) and P300 ERP components which overlap in time. TF transforms were computed using the binomial reduced interference distribution (RID), and the resulting TF activity was then characterized using principal components analysis (PCA). Consistent with previous work, results indicate that the FRN was more related to theta activity (3-7 Hz) and P300 more to delta activity (below 3 Hz). At the same time, both time-domain measures were shown to be mixtures of TF theta and delta activity, highlighting the difficulties with overlapping activity. The TF theta and delta measures, on the other hand, were largely independent from each other, but also independently indexed the feedback stimulus parameters investigated. Results support the view that TF decomposition can greatly improve separation of overlapping EEG/ERP activity relevant to cognitive models of performance monitoring.

  13. Mixed variational potentials and inherent symmetries of the Cahn-Hilliard theory of diffusive phase separation.

    PubMed

    Miehe, C; Hildebrand, F E; Böger, L

    2014-04-01

    This work shows that the Cahn-Hilliard theory of diffusive phase separation is related to an intrinsic mixed variational principle that determines the rate of concentration and the chemical potential. The principle characterizes a canonically compact model structure, where the two balances involved for the species content and microforce appear as the Euler equations of a variational statement. The existence of the variational principle underlines an inherent symmetry in the two-field representation of the Cahn-Hilliard theory. This can be exploited in the numerical implementation by the construction of time- and space-discrete incremental potentials, which fully determine the update problems of typical time-stepping procedures. The mixed variational principles provide the most fundamental approach to the finite-element solution of the Cahn-Hilliard equation based on low-order basis functions, leading to monolithic symmetric algebraic systems of iterative update procedures based on a linearization of the nonlinear problem. They induce in a natural format the choice of symmetric solvers for Newton-type iterative updates, providing a speed-up and reduction of data storage when compared with non-symmetric implementations. In this sense, the potentials developed are believed to be fundamental ingredients to a deeper understanding of the Cahn-Hilliard theory. PMID:24711722

  14. Mixed variational potentials and inherent symmetries of the Cahn-Hilliard theory of diffusive phase separation.

    PubMed

    Miehe, C; Hildebrand, F E; Böger, L

    2014-04-01

    This work shows that the Cahn-Hilliard theory of diffusive phase separation is related to an intrinsic mixed variational principle that determines the rate of concentration and the chemical potential. The principle characterizes a canonically compact model structure, where the two balances involved for the species content and microforce appear as the Euler equations of a variational statement. The existence of the variational principle underlines an inherent symmetry in the two-field representation of the Cahn-Hilliard theory. This can be exploited in the numerical implementation by the construction of time- and space-discrete incremental potentials, which fully determine the update problems of typical time-stepping procedures. The mixed variational principles provide the most fundamental approach to the finite-element solution of the Cahn-Hilliard equation based on low-order basis functions, leading to monolithic symmetric algebraic systems of iterative update procedures based on a linearization of the nonlinear problem. They induce in a natural format the choice of symmetric solvers for Newton-type iterative updates, providing a speed-up and reduction of data storage when compared with non-symmetric implementations. In this sense, the potentials developed are believed to be fundamental ingredients to a deeper understanding of the Cahn-Hilliard theory.

  15. Mixed variational potentials and inherent symmetries of the Cahn–Hilliard theory of diffusive phase separation

    PubMed Central

    Miehe, C.; Hildebrand, F. E.; Böger, L.

    2014-01-01

    This work shows that the Cahn–Hilliard theory of diffusive phase separation is related to an intrinsic mixed variational principle that determines the rate of concentration and the chemical potential. The principle characterizes a canonically compact model structure, where the two balances involved for the species content and microforce appear as the Euler equations of a variational statement. The existence of the variational principle underlines an inherent symmetry in the two-field representation of the Cahn–Hilliard theory. This can be exploited in the numerical implementation by the construction of time- and space-discrete incremental potentials, which fully determine the update problems of typical time-stepping procedures. The mixed variational principles provide the most fundamental approach to the finite-element solution of the Cahn–Hilliard equation based on low-order basis functions, leading to monolithic symmetric algebraic systems of iterative update procedures based on a linearization of the nonlinear problem. They induce in a natural format the choice of symmetric solvers for Newton-type iterative updates, providing a speed-up and reduction of data storage when compared with non-symmetric implementations. In this sense, the potentials developed are believed to be fundamental ingredients to a deeper understanding of the Cahn–Hilliard theory. PMID:24711722

  16. Amplitude Variation of Bottom Simulating Reflection with Respect to Frequency - Transitional Base or Attenuation?

    USGS Publications Warehouse

    Lee, Myung W.

    2007-01-01

    The amplitude of a bottom simulating reflection (BSR), which occurs near the phase boundary between gas hydrate-bearing sediments and underlying gas-filled sediments, strongly depends on the frequency content of a seismic signal, as well as the impedance contrast across the phase boundary. A strong-amplitude BSR, detectable in a conventional seismic profile, is a good indicator of the presence of free gas beneath the phase boundary. However, the BSR as observed in low-frequency multichannel seismic data is generally difficult to identify in high-frequency, single-channel seismic data. To investigate the frequency dependence of BSR amplitudes, single-channel seismic data acquired with an air gun source at Blake Ridge, which is located off the shore of South Carolina, were analyzed in the frequency range of 10-240 Hz. The frequency-dependent impedance contrast caused by the velocity dispersion in partially gas saturated sediments is important to accurately analyze BSR amplitude. Analysis indicates that seismic attenuation of gas hydrate-bearing sediments, velocity dispersion, and a transitional base all contribute to the frequency-dependent BSR amplitude variation in the frequency range of 10-500 Hz. When velocity dispersion is incorporated into the BSR amplitude analysis, the frequency-dependent BSR amplitude at Blake Ridge can be explained with gas hydrate-bearing sediments having a quality factor of about 250 and a transitional base with a thickness of about 1 meter.

  17. Solar-cycle variation of oscillation frequencies and surface magnetic field

    NASA Astrophysics Data System (ADS)

    Tan, S.; Thompson, M. J.; Centeno, R.

    2011-12-01

    We investigate the relationship between solar oscillation frequencies and surface magnetic fields over the course of the last solar cycle. Using MDI and GONG data, we study the variation in the even frequency-splitting coefficients ak (describing solar asphericity and effects of the magnetic field), and the variation in the coefficients Bk of the latitudinal Lengendre decomposition of the surface magnetic field, during the period 1996 - 2010. We find a strong linear correlation between the a and B coefficients, during both the rising and declining phases of the solar cycle, consistent with results published in 2001 (Antia et al.). We also investigated different ways to handle the magnetic field decomposition at the poles, and find that the linear correlation persists, though with varying intercepts. The variation of slope with coefficient index that we find is non-monotonic, which disagrees with the previous study by Antia et al. (2001).

  18. Analysis of all-frequency variational behavior of the Kirchhoff approximation for a classic surface-scattering model

    NASA Technical Reports Server (NTRS)

    Bird, J. F.

    1985-01-01

    In testing a stochastic variational principle at high frequencies by using a Kirchhoffean trial function in an idealized model for surface scattering - a randomly embossed plane - we have found not only the predicted high-frequency improvement but also an unexpected low-frequency improvement in the calculated scattering amplitudes. To investigate systematically the all-frequency variational behavior, we consider here the deterministic one-boss case - Rayleigh's classic model whose exact solution is available for comparison - over all wavelengths, polarizations, and configurations of incidence and scattering. We examine analytically in particular the long-wave limit of the variational-Kirchhoff amplitudes; the results demonstrate improvements in both wavelength and angle depedence for horizontal (TM) polarization and some variational improvements for vertical (TE) polarization. This low-frequency behavior in tandem with the foreseen high-frequency improvement leads to good variational-Kirchhoff results through the intermediate resonance-frequency regime for this model.

  19. Solution of the high-frequency variations of ERP from VLBI observations

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Li, Jin-ling; Wang, Guang-li; Zhao, Ming

    2005-07-01

    In the software CALC/SOLVE for the analysis of VLBI astrometric and geodetic data, the high-frequency variations of earth rotation parameters (ERP) are estimated by segmented linear fittings with additional constraints. That is, the rates of ERP between two epoch nodes are constrained to agree to within some preset value, and the ERP are required to be continuous at the nodes. Our analysis shows that when the data points are not very dense, the constraint and continuity requirement help to improve the stability of the solution, while at the same time they degrade the objectivity of the solution and make the solutions of ERP at different epoch nodes correlated. For this reason, based on the user partial entry of CALC/SOLVE, we have developed a module for the direct solution of the high-frequency variations of ERP, without the constraint on the ERP rate, nor the continuity requirement at the epoch nodes. It is shown by our reduction of real data that the direct solution mode is preferable. To derive the high-frequency variations of ERP from VLBI observations with a long time span, the error in the precession/nutation models (the celestial pole offset) should be taken into consideration and a corresponding module is developed. The global solutions of the high-frequency variations of ERP are successfully performed on the VLBI observations in the period from 1979 to 2003. It is demonstrated that when the errors in precession/nutation models are taken into consideration, the accuracy of the solution is noticeably improved. So, when seeking the high-frequency variations of ERP from VLBI observations, we recommend this direct solution mode, while taking the pole offset into consideration.

  20. Frequency Reuse, Cell Separation, and Capacity Analysis of VHF Digital Link Mode 3 TDMA

    NASA Technical Reports Server (NTRS)

    Shamma, Mohammed A.; Nguyen, Thanh C.; Apaza, Rafael D.

    2003-01-01

    The most recent studies by the Federal Aviation Administration (FAA) and the aviation industry have indicated that it has become increasingly difficult to make new VHF frequency or channel assignments to meet the aviation needs for air-ground communications. FAA has planned for several aggressive improvement measures to the existing systems, but these measures would not meet the projected voice communications needs beyond 2009. FAA found that since 1974 there has been, on the average, a 4 percent annual increase in the number of channel assignments needed to satisfy the air-ground communication traffic (approximately 300 new channel assignments per year). With the planned improvement measures, the channel assignments are expected to reach a maximum number of 16615 channels by about 2010. Hence, the FAA proposed the use of VDL Mode 3 as a new integrated digital voice and data communications systems to meet the future air traffic demand. This paper presents analytical results of frequency reuse; cell separation and capacity estimation of VDL Mode 3 TDMA systems that FAA has planned to implement the future VHF air-ground communications system by the year 2010. For TDMA, it is well understood that the frequency reuse factor is a crucial parameter for capacity estimation. Formulation of this frequency reuse factor is shown, taking into account the limitation imposed by the requirement to have a sufficient Signal to Co-Channel Interference Ratio. Several different values for the Signal to Co-Channel Interference Ratio were utilized corresponding to the current analog VHF DSB-AM systems, and the future digital VDL Mode 3. The required separation of Co-Channel cells is computed for most of the Frequency Protected Service Volumes (FPSV's) currently in use by the FAA. Additionally, the ideal cell capacity for each FPSV is presented. Also, using actual traffic for the Detroit air space, a FPSV traffic distribution model is used to generate a typical cell for channel capacity

  1. Detection of sudden structural damage using blind source separation and time-frequency approaches

    NASA Astrophysics Data System (ADS)

    Morovati, V.; Kazemi, M. T.

    2016-05-01

    Seismic signal processing is one of the most reliable methods of detecting the structural damage during earthquakes. In this paper, the use of the hybrid method of blind source separation (BSS) and time-frequency analysis (TFA) is explored to detect the changes in the structural response data. The combination of the BSS and TFA is applied to the seismic signals due to the non-stationary nature of them. Firstly, the second-order blind identification technique is used to decompose the response signal of structural vibration into modal coordinate signals which will be mono-components for TFA. Then each mono-component signal is analyzed to extract instantaneous frequency of structure. Numerical simulations and a real-world seismic-excited structure with time-varying frequencies show the accuracy and robustness of the developed algorithm. TFA of extracted sources shows that used method can be successfully applied to structural damage detection. The results also demonstrate that the combined method can be used to identify the time instant of structural damage occurrence more sharply and effectively than by the use of TFA alone.

  2. Tailoring Surface Properties of Polymeric Separators for Lithium-Ion Batteries by 13.56 MHz Radio-Frequency Plasma Glow Discharge

    NASA Astrophysics Data System (ADS)

    Liang, Chia-Han; Juang, Ruey-Shin; Tsai, Ching-Yuan; Huang, Chun

    2013-11-01

    The hydrophilic surface modification of the polymeric separator is achieved by low-pressure 13.56 MHz radio-frequency Ar and He gas plasma treatments. The changes in surface hydrophilicity and surface free energy were examined by static contact angle analysis. The static water contact angle of the plasma-modified polymeric separator particularly decreased with the increase in treatment time. An obvious increase in the surface energy of polymeric separators owing to the crosslinking by activated species of inert gases effect of monatomic-gas-plasma treatments was also observed. Optical emission spectroscopy was carried out to analyze the chemical species generated after Ar and He gas plasma treatments. The variations in the surface morphology and chemical structure of the polymeric separators were confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS) measurements. XPS analysis showed significantly higher surface concentrations of oxygen functional groups for monatomic-gas-plasma-modified polymeric separator surfaces than for the unmodified polymeric separator surface. The experimental results show the important role of chemical species in the interaction between Ar and He gas plasmas and the polymeric separator surface, which can be controlled by surface modification to tailor the hydrophilicity of the polymeric separator.

  3. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

    DOEpatents

    Skupsky, Stanley; Craxton, R. Stephen; Soures, John

    1990-01-01

    In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temoral oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation.

  4. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

    DOEpatents

    Skupsky, S.; Craxton, R.S.; Soures, J.

    1990-10-02

    In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temporal oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation. 16 figs.

  5. High-frequency variations of hydrogen spectral lines in the B3V star η UMa

    NASA Astrophysics Data System (ADS)

    Pokhvala, S. M.

    2015-09-01

    We reported the detection of high-frequency variations in the hydrogen Balmer lines in the hot star η UMa of spectral class B3V. Spectral observations of η UMa were carried out with slitless spectrograph (R˜100) installed on the 60 cm Carl Zeiss telescope in the Andrushivka Observatory. Spectra were obtained with a time resolution in the sub-second range. It has been found that the η UMa shows rapid variations in the hydrogen lines Hα, Hβ, Hγ, as well as variations in the atmospheric oxygen lines. The intensity variations in the hydrogen lines varies from 0.2% to 0.5% , and that of the oxygen lines is approximately 2%.

  6. Frequency variations of the earth's obliquity and the 100-kyr ice-age cycles

    NASA Technical Reports Server (NTRS)

    Liu, Han-Shou

    1992-01-01

    Changes in the earth's climate are induced by variations in the earth's orbital parameters which modulate the seasonal distribution of solar radiation. Periodicities in the geological climate record with cycles of 100, 41, and 23 kyr have been linked with changes in obliquity, eccentricity, and precession of the equinoxes. The effect of variations of eccentricity during a 100 kyr period is weak relative to the signals from obliquity and precession variations and it may therefore be expected that the 100 kyr signal in the climate record would be of low intensity. However, this signal dominates the climate record and internal nonlinear processes within the climate system have previously been proposed to account for this fact. The author shows that variations in the frequency of the obliquity cycle can give rise to strong 100-kyr forcing of climate.

  7. The effects of actuation frequency on the separation control over an airfoil using a synthetic jet

    NASA Astrophysics Data System (ADS)

    Abe, Y.; Okada, K.; Nonomura, T.; Fujii, K.

    2015-06-01

    The simulation of separation control using a synthetic jet (SJ) is conducted around an NACA (National Advisory Committee for Aeronautics) 0015 airfoil by large-eddy simulation (LES) with a compact difference scheme. The synthetic jet is installed at the leading edge of the airfoil and the effects of an actuation frequency F+ (normalized by chord length and velocity of freestream) are observed. The lift-drag coefficient is recovered the most for F+ = 6. The relationship between momentum addition by turbulent mixing and large vortex structures is investigated using a phase-averaging procedure based on F+. The Reynolds shear stress is decomposed into periodic and turbulent components where the turbulent components are found to be dominant on the airfoil. The strong turbulent components appear near the large vortex structures that are observed in phase- and span-averaged flow fields.

  8. Top down and bottom up selection drives variations in frequency and form of a visual signal

    PubMed Central

    Yeh, Chien-Wei; Blamires, Sean J.; Liao, Chen-Pan; Tso, I.-Min

    2015-01-01

    The frequency and form of visual signals can be shaped by selection from predators, prey or both. When a signal simultaneously attracts predators and prey, selection may favour a strategy that minimizes risks while attracting prey. Accordingly, varying the frequency and form of the silken decorations added to their web may be a way that Argiope spiders minimize predation while attracting prey. Nonetheless, the role of extraneous factors renders the influences of top down and bottom up selection on decoration frequency and form variation difficult to discern. Here we used dummy spiders and decorations to simulate four possible strategies that the spider Argiope aemula may choose and measured the prey and predator attraction consequences for each in the field. The strategy of decorating at a high frequency with a variable form attracted the most prey, while that of decorating at a high frequency with a fixed form attracted the most predators. These results suggest that mitigating the cost of attracting predators while maintaining prey attraction drives the use of variation in decoration form by many Argiope spp. when decorating frequently. Our study highlights the importance of considering top-down and bottom up selection pressure when devising evolutionary ecology experiments. PMID:25828030

  9. Frequency-independent approach to calculate physical optics radiations with the quadratic concave phase variations

    NASA Astrophysics Data System (ADS)

    Wu, Yu Mao; Teng, Si Jia

    2016-11-01

    In this work, we develop the numerical steepest descent path (NSDP) method to calculate the physical optics (PO) radiations with the quadratic concave phase variations. With the surface integral equation method, the physical optics (PO) scattered fields are formulated and further reduced to the surface integrals. The high frequency physical critical points contributions, including the stationary phase points, the boundary resonance points and the vertex points are comprehensively studied via the proposed NSDP method. The key contributions of this work are twofold. One is that together with the PO integrals taking the quadratic parabolic and hyperbolic phase terms, this work makes the NSDP theory be complete for treating the PO integrals with quadratic phase variations. Another is that, in order to illustrate the transition effect of the high frequency physical critical points, in this work, we consider and further extend the NSDP method to calculate the PO integrals with the coalescence of the high frequency critical points. Numerical results for the highly oscillatory PO integral with the coalescence of the critical points are given to verify the efficiency of the proposed NSDP method. The NSDP method could achieve the frequency independent computational workload and error controllable accuracy in all the numerical experiments, especially for the case of the coalescence of the high frequency critical points.

  10. Top down and bottom up selection drives variations in frequency and form of a visual signal.

    PubMed

    Yeh, Chien-Wei; Blamires, Sean J; Liao, Chen-Pan; Tso, I-Min

    2015-01-01

    The frequency and form of visual signals can be shaped by selection from predators, prey or both. When a signal simultaneously attracts predators and prey selection may favour a strategy that minimizes risks while attracting prey. Accordingly, varying the frequency and form of the silken decorations added to their web may be a way that Argiope spiders minimize predation while attracting prey. Nonetheless, the role of extraneous factors renders the influences of top down and bottom up selection on decoration frequency and form variation difficult to discern. Here we used dummy spiders and decorations to simulate four possible strategies that the spider Argiope aemula may choose and measured the prey and predator attraction consequences for each in the field. The strategy of decorating at a high frequency with a variable form attracted the most prey, while that of decorating at a high frequency with a fixed form attracted the most predators. These results suggest that mitigating the cost of attracting predators while maintaining prey attraction drives the use of variation in decoration form by many Argiope spp. when decorating frequently. Our study highlights the importance of considering top-down and bottom up selection pressure when devising evolutionary ecology experiments.

  11. Theoretical analysis of the EAST 4-strap ion cyclotron range of frequency antenna with variational theory

    NASA Astrophysics Data System (ADS)

    Zhang, Jia-Hui; Zhang, Xin-Jun; Zhao, Yan-Ping; Qin, Cheng-Ming; Chen, Zhao; Yang, Lei; Wang, Jian-Hua

    2016-08-01

    A variational principle code which can calculate self-consistently currents on the conductors is used to assess the coupling characteristic of the EAST 4-strap ion cyclotron range of frequency (ICRF) antenna. Taking into account two layers of antenna conductors without lateral frame but with slab geometry, the antenna impedances as a function of frequency and the structure of RF field excited inside the plasma in various phasing cases are discussed in this paper. Project supported by the National Magnetic Confinement Fusion Science Program, China (Grant No. 2015GB101001) and the National Natural Science Foundation of China (Grant Nos. 11375236 and 11375235).

  12. Theoretical analysis of the EAST 4-strap ion cyclotron range of frequency antenna with variational theory

    NASA Astrophysics Data System (ADS)

    Zhang, Jia-Hui; Zhang, Xin-Jun; Zhao, Yan-Ping; Qin, Cheng-Ming; Chen, Zhao; Yang, Lei; Wang, Jian-Hua

    2016-08-01

    A variational principle code which can calculate self-consistently currents on the conductors is used to assess the coupling characteristic of the EAST 4-strap ion cyclotron range of frequency (ICRF) antenna. Taking into account two layers of antenna conductors without lateral frame but with slab geometry, the antenna impedances as a function of frequency and the structure of RF field excited inside the plasma in various phasing cases are discussed in this paper. Project supported by the National Magnetic Confinement Fusion Science Program, China (Grant No. 2015GB101001) and the National Natural Science Foundation of China (Grant Nos. 11375236 and 11375235).

  13. Separation of Radio-Frequency Sources and Localization of Partial Discharges in Noisy Environments

    PubMed Central

    Robles, Guillermo; Fresno, José Manuel; Martínez-Tarifa, Juan Manuel

    2015-01-01

    The detection of partial discharges (PD) can help in early-warning detection systems to protect critical assets in power systems. The radio-frequency emission of these events can be measured with antennas even when the equipment is in service which reduces dramatically the maintenance costs and favours the implementation of condition-based monitoring systems. The drawback of these type of measurements is the difficulty of having a reference signal to study the events in a classical phase-resolved partial discharge pattern (PRPD). Therefore, in open-air substations and overhead lines where interferences from radio and TV broadcasting and mobile communications are important sources of noise and other pulsed interferences from rectifiers or inverters can be present, it is difficult to identify whether there is partial discharges activity or not. This paper proposes a robust method to separate the events captured with the antennas, identify which of them are partial discharges and localize the piece of equipment that is having problems. The separation is done with power ratio (PR) maps based on the spectral characteristics of the signal and the identification of the type of event is done localizing the source with an array of four antennas. Several classical methods to calculate the time differences of arrival (TDOA) of the emission to the antennas have been tested, and the localization is done using particle swarm optimization (PSO) to minimize a distance function. PMID:25923935

  14. High frequency variations of Earth Rotation Parameters from GPS and GLONASS observations.

    PubMed

    Wei, Erhu; Jin, Shuanggen; Wan, Lihua; Liu, Wenjie; Yang, Yali; Hu, Zhenghong

    2015-01-28

    The Earth's rotation undergoes changes with the influence of geophysical factors, such as Earth's surface fluid mass redistribution of the atmosphere, ocean and hydrology. However, variations of Earth Rotation Parameters (ERP) are still not well understood, particularly the short-period variations (e.g., diurnal and semi-diurnal variations) and their causes. In this paper, the hourly time series of Earth Rotation Parameters are estimated using Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), and combining GPS and GLONASS data collected from nearly 80 sites from 1 November 2012 to 10 April 2014. These new observations with combining different satellite systems can help to decorrelate orbit biases and ERP, which improve estimation of ERP. The high frequency variations of ERP are analyzed using a de-trending method. The maximum of total diurnal and semidiurnal variations are within one milli-arcseconds (mas) in Polar Motion (PM) and 0.5 milli-seconds (ms) in UT1-UTC. The semidiurnal and diurnal variations are mainly related to the ocean tides. Furthermore, the impacts of satellite orbit and time interval used to determinate ERP on the amplitudes of tidal terms are analyzed. We obtain some small terms that are not described in the ocean tide model of the IERS Conventions 2010, which may be caused by the strategies and models we used or the signal noises as well as artifacts. In addition, there are also small differences on the amplitudes between our results and IERS convention. This might be a result of other geophysical excitations, such as the high-frequency variations in atmospheric angular momentum (AAM) and hydrological angular momentum (HAM), which needs more detailed analysis with more geophysical data in the future.

  15. High frequency variations of Earth Rotation Parameters from GPS and GLONASS observations.

    PubMed

    Wei, Erhu; Jin, Shuanggen; Wan, Lihua; Liu, Wenjie; Yang, Yali; Hu, Zhenghong

    2015-01-01

    The Earth's rotation undergoes changes with the influence of geophysical factors, such as Earth's surface fluid mass redistribution of the atmosphere, ocean and hydrology. However, variations of Earth Rotation Parameters (ERP) are still not well understood, particularly the short-period variations (e.g., diurnal and semi-diurnal variations) and their causes. In this paper, the hourly time series of Earth Rotation Parameters are estimated using Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), and combining GPS and GLONASS data collected from nearly 80 sites from 1 November 2012 to 10 April 2014. These new observations with combining different satellite systems can help to decorrelate orbit biases and ERP, which improve estimation of ERP. The high frequency variations of ERP are analyzed using a de-trending method. The maximum of total diurnal and semidiurnal variations are within one milli-arcseconds (mas) in Polar Motion (PM) and 0.5 milli-seconds (ms) in UT1-UTC. The semidiurnal and diurnal variations are mainly related to the ocean tides. Furthermore, the impacts of satellite orbit and time interval used to determinate ERP on the amplitudes of tidal terms are analyzed. We obtain some small terms that are not described in the ocean tide model of the IERS Conventions 2010, which may be caused by the strategies and models we used or the signal noises as well as artifacts. In addition, there are also small differences on the amplitudes between our results and IERS convention. This might be a result of other geophysical excitations, such as the high-frequency variations in atmospheric angular momentum (AAM) and hydrological angular momentum (HAM), which needs more detailed analysis with more geophysical data in the future. PMID:25635416

  16. High Frequency Variations of Earth Rotation Parameters from GPS and GLONASS Observations

    PubMed Central

    Wei, Erhu; Jin, Shuanggen; Wan, Lihua; Liu, Wenjie; Yang, Yali; Hu, Zhenghong

    2015-01-01

    The Earth's rotation undergoes changes with the influence of geophysical factors, such as Earth's surface fluid mass redistribution of the atmosphere, ocean and hydrology. However, variations of Earth Rotation Parameters (ERP) are still not well understood, particularly the short-period variations (e.g., diurnal and semi-diurnal variations) and their causes. In this paper, the hourly time series of Earth Rotation Parameters are estimated using Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), and combining GPS and GLONASS data collected from nearly 80 sites from 1 November 2012 to 10 April 2014. These new observations with combining different satellite systems can help to decorrelate orbit biases and ERP, which improve estimation of ERP. The high frequency variations of ERP are analyzed using a de-trending method. The maximum of total diurnal and semidiurnal variations are within one milli-arcseconds (mas) in Polar Motion (PM) and 0.5 milli-seconds (ms) in UT1-UTC. The semidiurnal and diurnal variations are mainly related to the ocean tides. Furthermore, the impacts of satellite orbit and time interval used to determinate ERP on the amplitudes of tidal terms are analyzed. We obtain some small terms that are not described in the ocean tide model of the IERS Conventions 2010, which may be caused by the strategies and models we used or the signal noises as well as artifacts. In addition, there are also small differences on the amplitudes between our results and IERS convention. This might be a result of other geophysical excitations, such as the high-frequency variations in atmospheric angular momentum (AAM) and hydrological angular momentum (HAM), which needs more detailed analysis with more geophysical data in the future. PMID:25635416

  17. Radio-frequency-driven dipole-dipole interactions in spatially separated volumes

    NASA Astrophysics Data System (ADS)

    Tauschinsky, Atreju; van Ditzhuijzen, C. S. E.; Noordam, L. D.; van den Heuvell, H. B. Van Linden

    2008-12-01

    Radio-frequency (rf) fields in the MHz range are used to induce resonant energy transfer between cold Rydberg atoms in spatially separated volumes. After laser preparation of the Rydberg atoms, dipole-dipole coupling excites the 49s atoms in one cylinder to the 49p state while the 41d atoms in the second cylinder are transferred down to the 42p state. The energy exchanged between the atoms in this process is 33GHz . An external rf field brings this energy transfer into resonance. The strength of the interaction has been investigated as a function of amplitude (0-1V/cm) and frequency (1-30MHz) of the rf field and as a function of a static-field offset. Multiphoton transitions up to fifth order as well as selection rules prohibiting the process at certain fields have been observed. The width of the resonances has been reduced compared to earlier results by switching off external magnetic fields of the magneto-optical trap, making sub-MHz spectroscopy possible. All features are well reproduced by theoretical calculations taking the strong ac Stark shift due to the rf field into account.

  18. Formant-frequency variation and informational masking of speech by extraneous formants: evidence against dynamic and speech-specific acoustical constraints.

    PubMed

    Roberts, Brian; Summers, Robert J; Bailey, Peter J

    2014-08-01

    How speech is separated perceptually from other speech remains poorly understood. Recent research indicates that the ability of an extraneous formant to impair intelligibility depends on the variation of its frequency contour. This study explored the effects of manipulating the depth and pattern of that variation. Three formants (F1+F2+F3) constituting synthetic analogues of natural sentences were distributed across the 2 ears, together with a competitor for F2 (F2C) that listeners must reject to optimize recognition (left = F1+F2C; right = F2+F3). The frequency contours of F1 - F3 were each scaled to 50% of their natural depth, with little effect on intelligibility. Competitors were created either by inverting the frequency contour of F2 about its geometric mean (a plausibly speech-like pattern) or using a regular and arbitrary frequency contour (triangle wave, not plausibly speech-like) matched to the average rate and depth of variation for the inverted F2C. Adding a competitor typically reduced intelligibility; this reduction depended on the depth of F2C variation, being greatest for 100%-depth, intermediate for 50%-depth, and least for 0%-depth (constant) F2Cs. This suggests that competitor impact depends on overall depth of frequency variation, not depth relative to that for the target formants. The absence of tuning (i.e., no minimum in intelligibility for the 50% case) suggests that the ability to reject an extraneous formant does not depend on similarity in the depth of formant-frequency variation. Furthermore, triangle-wave competitors were as effective as their more speech-like counterparts, suggesting that the selection of formants from the ensemble also does not depend on speech-specific constraints. PMID:24842068

  19. Collective frequency variation in network synchronization and reverse PageRank.

    PubMed

    Skardal, Per Sebastian; Taylor, Dane; Sun, Jie; Arenas, Alex

    2016-04-01

    A wide range of natural and engineered phenomena rely on large networks of interacting units to reach a dynamical consensus state where the system collectively operates. Here we study the dynamics of self-organizing systems and show that for generic directed networks the collective frequency of the ensemble is not the same as the mean of the individuals' natural frequencies. Specifically, we show that the collective frequency equals a weighted average of the natural frequencies, where the weights are given by an outflow centrality measure that is equivalent to a reverse PageRank centrality. Our findings uncover an intricate dependence of the collective frequency on both the structural directedness and dynamical heterogeneity of the network, and also reveal an unexplored connection between synchronization and PageRank, which opens the possibility of applying PageRank optimization to synchronization. Finally, we demonstrate the presence of collective frequency variation in real-world networks by considering the UK and Scandinavian power grids. PMID:27176319

  20. PULSAR TIMING ERRORS FROM ASYNCHRONOUS MULTI-FREQUENCY SAMPLING OF DISPERSION MEASURE VARIATIONS

    SciTech Connect

    Lam, M. T.; Cordes, J. M.; Chatterjee, S.; Dolch, T.

    2015-03-10

    Free electrons in the interstellar medium cause frequency-dependent delays in pulse arrival times due to both scattering and dispersion. Multi-frequency measurements are used to estimate and remove dispersion delays. In this paper, we focus on the effect of any non-simultaneity of multi-frequency observations on dispersive delay estimation and removal. Interstellar density variations combined with changes in the line of sight from pulsar and observer motions cause dispersion measure (DM) variations with an approximately power-law power spectrum, augmented in some cases by linear trends. We simulate time series, estimate the magnitude and statistical properties of timing errors that result from non-simultaneous observations, and derive prescriptions for data acquisition that are needed in order to achieve a specified timing precision. For nearby, highly stable pulsars, measurements need to be simultaneous to within about one day in order for the timing error from asynchronous DM correction to be less than about 10 ns. We discuss how timing precision improves when increasing the number of dual-frequency observations used in DM estimation for a given epoch. For a Kolmogorov wavenumber spectrum, we find about a factor of two improvement in precision timing when increasing from two to three observations but diminishing returns thereafter.

  1. In situ cardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles.

    PubMed

    Joyce, William; Axelsson, Michael; Altimiras, Jordi; Wang, Tobias

    2016-07-15

    The ventricles of non-crocodilian reptiles are incompletely divided and provide an opportunity for mixing of oxygen-poor blood and oxygen-rich blood (intracardiac shunting). However, both cardiac morphology and in vivo shunting patterns exhibit considerable interspecific variation within reptiles. In the present study, we develop an in situ double-perfused heart approach to characterise the propensity and capacity for shunting in five reptile species: the turtle Trachemys scripta, the rock python Python sebae, the yellow anaconda Eunectes notaeus, the varanid lizard Varanus exanthematicus and the bearded dragon Pogona vitticeps To simulate changes in vascular bed resistance, pulmonary and systemic afterloads were independently manipulated and changes in blood flow distribution amongst the central outflow tracts were monitored. As previously demonstrated in Burmese pythons, rock pythons and varanid lizards exhibited pronounced intraventricular flow separation. As pulmonary or systemic afterload was raised, flow in the respective circulation decreased. However, flow in the other circulation, where afterload was constant, remained stable. This correlates with the convergent evolution of intraventricular pressure separation and the large intraventricular muscular ridge, which compartmentalises the ventricle, in these species. Conversely, in the three other species, the pulmonary and systemic flows were strongly mutually dependent, such that the decrease in pulmonary flow in response to elevated pulmonary afterload resulted in redistribution of perfusate to the systemic circuit (and vice versa). Thus, in these species, the muscular ridge appeared labile and blood could readily transverse the intraventricular cava. We conclude that relatively minor structural differences between non-crocodilian reptiles result in the fundamental changes in cardiac function. Further, our study emphasises that functionally similar intracardiac flow separation evolved independently in

  2. In situ cardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles.

    PubMed

    Joyce, William; Axelsson, Michael; Altimiras, Jordi; Wang, Tobias

    2016-07-15

    The ventricles of non-crocodilian reptiles are incompletely divided and provide an opportunity for mixing of oxygen-poor blood and oxygen-rich blood (intracardiac shunting). However, both cardiac morphology and in vivo shunting patterns exhibit considerable interspecific variation within reptiles. In the present study, we develop an in situ double-perfused heart approach to characterise the propensity and capacity for shunting in five reptile species: the turtle Trachemys scripta, the rock python Python sebae, the yellow anaconda Eunectes notaeus, the varanid lizard Varanus exanthematicus and the bearded dragon Pogona vitticeps To simulate changes in vascular bed resistance, pulmonary and systemic afterloads were independently manipulated and changes in blood flow distribution amongst the central outflow tracts were monitored. As previously demonstrated in Burmese pythons, rock pythons and varanid lizards exhibited pronounced intraventricular flow separation. As pulmonary or systemic afterload was raised, flow in the respective circulation decreased. However, flow in the other circulation, where afterload was constant, remained stable. This correlates with the convergent evolution of intraventricular pressure separation and the large intraventricular muscular ridge, which compartmentalises the ventricle, in these species. Conversely, in the three other species, the pulmonary and systemic flows were strongly mutually dependent, such that the decrease in pulmonary flow in response to elevated pulmonary afterload resulted in redistribution of perfusate to the systemic circuit (and vice versa). Thus, in these species, the muscular ridge appeared labile and blood could readily transverse the intraventricular cava. We conclude that relatively minor structural differences between non-crocodilian reptiles result in the fundamental changes in cardiac function. Further, our study emphasises that functionally similar intracardiac flow separation evolved independently in

  3. Cyclic variations of high-frequency ultrasonic backscattering from blood under pulsatile flow.

    PubMed

    Huang, Chih-Chung

    2009-08-01

    It was shown previously that ultrasonic scattering from whole blood varies during the flow cycle under pulsatile flow both in vitro and in vivo. It has been postulated that the cyclic variations of the backscattering signal are associated with red blood cell (RBC) aggregation in flowing whole blood. To obtain a better understanding of the relationship between blood backscattering and RBC aggregation behavior for pulsatile flowing blood, the present study used high-frequency ultrasound to characterize blood properties. The backscattering signals from both whole blood and an RBC suspension at different peak flow velocities (from 10 to 30 cm/s) and hematocrits (20% and 40%) under pulsatile flow (stroke rate of 20 beats/min) were measured with 3 single-element transducers at frequencies of 10, 35, and 50 MHz in a mock flow loop. To avoid the frequency response problem of a Doppler flowmeter, the integrated backscatter (IB) and flow velocity as functions of time were calculated directly using RF signals from flowing blood. The experimental results showed that cyclic variations of the IB curve were clearly observed at a low flow velocity and a hematocrit of 40% when using 50 MHz ultrasound, and that these variations became weaker as the peak flow velocity increased. However, these cyclic variations were detected only at 10 cm/s when using 10 MHz ultrasound. These results demonstrate that a high flow velocity can stop the formation of rouleaux and that a high hematocrit can promote RBC aggregation to produce cyclic variations of the backscattering signal under pulsatile flow. In addition, slight cyclic variations of the IB curve for an RBC suspension were observed at 35 and 50 MHz. Furthermore, the peak of the IB curve from whole blood led the peak of the velocity waveform when using high-frequency ultrasound, which could be explained by the assumption that a rapid flow can promote RBC aggregation under pulsatile flow. Together, the experimental results showed that the

  4. Extended high-frequency bandwidth improves reception of speech in spatially separated masking speech

    PubMed Central

    Levy, Suzanne Carr; Freed, Daniel J.; Nilsson, Michael; Moore, Brian C.J.; Puria, Sunil

    2015-01-01

    Objectives The hypothesis that extending the audible frequency bandwidth beyond the range currently implemented in most hearing aids can improve speech understanding was tested for normal-hearing and hearing-impaired participants using target sentences and spatially separated masking speech. Design The Hearing in Noise Test (HINT) speech corpus was re-recorded and four masking talkers were recorded at a sample rate of 44.1 kHz. All talkers were male native speakers of American English. Reception threshold for Sentences (RTS) were measured in two spatial configurations. In the asymmetric configuration, the target was presented from −45° azimuth and two colocated masking talkers were presented from +45° azimuth. In the diffuse configuration, the target was presented from 0° azimuth and four masking talkers were each presented from a different azimuth: +45°, +135°, −135°, and −45°. The new speech sentences, masking materials and configurations, collectively termed the ‘Hearing in Speech Test (HIST)’, were presented using lowpass filter cutoff frequencies of 4, 6, 8, and 10 kHz. For the normal-hearing participants, stimuli were presented in the sound field using loudspeakers. For the hearing-impaired participants, the spatial configurations were simulated using earphones, and a multi-band wide dynamic range compressor with a modified CAM2 fitting algorithm was used to compensate for each participant’s hearing loss. Results For the normal-hearing participants (N=24, mean age 40 years), the RTS improved significantly by 3.0 dB when the bandwidth was increased from 4 to 10 kHz, and a significant improvement of 1.3 dB was obtained from extending the bandwidth from 6 to 10 kHz, in both spatial configurations. Hearing-impaired participants (N=25, mean age 71 years) also showed a significant improvement in RTS with extended bandwidth, but the effect was smaller than for the normal-hearing participants. The mean decrease in RTS when the bandwidth was

  5. Variation in Cardiac Pulse Frequencies Modulates vSMC Phenotype Switching During Vascular Remodeling.

    PubMed

    Tosun, Zehra; McFetridge, Peter S

    2015-03-01

    In vitro perfusion systems have exposed vascular constructs to mechanical conditions that emulate physiological pulse pressure and found significant improvements in graft development. However, current models maintain constant, or set pulse/shear mechanics that do not account for the natural temporal variation in frequency. With an aim to develop clinically relevant small diameter vascular grafts, these investigations detail a perfusion culture model that incorporates temporal pulse pressure variation. Our objective was to test the hypothesis that short-term variation in heart rate, such as changes in respiratory activity, plays a significant role in vascular remodeling and graft development. The pulse rate of a healthy volunteer was logged to model the effect of daily activities on heart rate. Vascular bioreactors were used to deliver perfusion conditions based on modeled frequencies of temporal pulse variability, termed Physiologically Modeled Pulse Dynamics (PMPD). Acellular scaffolds derived from the human umbilical vein were seeded with human vascular smooth muscle cells and perfused under defined pulsatile conditions. vSMC exposed to constant pulse frequencies expressed a contractile phenotype, while exposure to PMPD drove cells to a synthetic state with continued cell proliferation, increased tensile strength and stiffness as well as diminished vasoactivity. Results show the temporal variation associated with normal heart physiology to have a profound effect on vascular remodeling and vasoactive function. While these models are representative of vascular regeneration further investigation is required to understanding these and other key regulators in vSMC phenotype switching in non-pathological or wound healing states. This understanding has important clinical implications that may lead to improved treatments that enhance vessel regeneration. PMID:26577103

  6. Gate line edge roughness amplitude and frequency variation effects on intra die MOS device characteristics

    NASA Astrophysics Data System (ADS)

    Hamadeh, Emad; Gunther, Norman G.; Niemann, Darrell; Rahman, Mahmud

    2006-06-01

    Random fluctuations in fabrication process outcomes such as gate line edge roughness (LER) give rise to corresponding fluctuations in scaled down MOS device characteristics. A thermodynamic-variational model is presented to study the effects of LER on threshold voltage and capacitance of sub-50 nm MOS devices. Conceptually, we treat the geometric definition of the MOS devices on a die as consisting of a collection of gates. In turn, each of these gates has an area, A, and a perimeter, P, defined by nominally straight lines subject to random process outcomes producing roughness. We treat roughness as being deviations from straightness consisting of both transverse amplitude and longitudinal wavelength each having lognormal distribution. We obtain closed-form expressions for variance of threshold voltage ( Vth), and device capacitance ( C) at Onset of Strong Inversion (OSI) for a small device. Using our variational model, we characterized the device electrical properties such as σ and σC in terms of the statistical parameters of the roughness amplitude and spatial frequency, i.e., inverse roughness wavelength. We then verified our model with numerical analysis of Vth roll-off for small devices and σ due to dopant fluctuation. Our model was also benchmarked against TCAD of σ as a function of LER. We then extended our analysis to predict variations in σ and σC versus average LER spatial frequency and amplitude, and oxide-thickness. Given the intuitive expectation that LER of very short wavelengths must also have small amplitude, we have investigated the case in which the amplitude mean is inversely related to the frequency mean. We compare with the situation in which amplitude and frequency mean are unrelated. Given also that the gate perimeter may consist of different LER signature for each side, we have extended our analysis to the case when the LER statistical difference between gate sides is moderate, as well as when it is significantly large.

  7. Blind source separation based on time-frequency morphological characteristics for rigid acoustic scattering by underwater objects

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Li, Xiukun

    2016-06-01

    Separation of the components of rigid acoustic scattering by underwater objects is essential in obtaining the structural characteristics of such objects. To overcome the problem of rigid structures appearing to have the same spectral structure in the time domain, time-frequency Blind Source Separation (BSS) can be used in combination with image morphology to separate the rigid scattering components of different objects. Based on a highlight model, the separation of the rigid scattering structure of objects with time-frequency distribution is deduced. Using a morphological filter, different characteristics in a Wigner-Ville Distribution (WVD) observed for single auto term and cross terms can be simplified to remove any cross-term interference. By selecting time and frequency points of the auto terms signal, the accuracy of BSS can be improved. An experimental simulation has been used, with changes in the pulse width of the transmitted signal, the relative amplitude and the time delay parameter, in order to analyzing the feasibility of this new method. Simulation results show that the new method is not only able to separate rigid scattering components, but can also separate the components when elastic scattering and rigid scattering exist at the same time. Experimental results confirm that the new method can be used in separating the rigid scattering structure of underwater objects.

  8. Frequency of t(14;18) in follicular lymphoma patients: geographical or technical variation.

    PubMed

    Ismail, S I; Sughayer, M A; Al-Quadan, T F; Qaqish, B M; Tarawneh, M S

    2009-10-01

    The t(14;18) translocation is the most distinguishing molecular finding in follicular lymphoma (FL). However, the reported frequencies of t(14;18) in FL show significant variation, which is often attributed to geographical and/or methodological factors. The methods used to detect t(14;18) include Southern blotting, conventional cytogenetics, fluorescent in situ hybridization, and polymerized chain reaction (PCR). Because of its practicality and superior sensitivity, PCR is becoming the more commonly used method in clinical laboratories. The identification of the main breakpoint regions on chromosome 18, including the major breakpoint region (MBR), the minor cluster region (mcr), and the newly defined intermediate cluster region (icr), increased the detection frequency of PCR. In our study, using a highly sensitive nested PCR strategy with primers for MBR, mcr and icr regions, we were able to detect t(14;18) in 95% of FL patients, which is one of the highest reported frequencies using PCR. We screened 58 FL patient samples collected retrospectively from different hospitals in Jordan. DNA was extracted from archival paraffin-embedded samples, some of which were >10 years old. The respective breakpoint distributions were, 47 for MBR (81%), two for mcr (3.5%) and six for icr (10.3%). In this report, we analyze this high frequency of t(14;18) detection in a general review of the recent literature, in an attempt to assess the geographical vs. methodological influences on the reported frequencies.

  9. Measuring frequency changes due to microwave power variations as a function of C-field setting in a rubidium frequency standard

    NASA Technical Reports Server (NTRS)

    Sarosy, E. B.; Johnson, Walter A.; Karuza, Sarunas K.; Voit, Frank J.

    1992-01-01

    It has been shown in previous studies that in some cesium frequency standards there exist certain C-field settings that minimize frequency changes that are due to variations in the microwave power. In order to determine whether similar results could be obtained with rubidium (Rb) frequency standards (clocks), we performed a similar study, using a completely automated measurement system, on a commercial Rb standard. From our measurements we found that changing the microwave power to the filter cell resulted in significant changes in frequency, and that the magnitude of these frequency changes at low C-field levels went to zero and decreased as the C-field was increased.

  10. A direct numerical simulation investigation of the synthetic jet frequency effects on separation control of low-Re flow past an airfoil

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Samtaney, Ravi

    2015-05-01

    We present results of direct numerical simulations of a synthetic jet (SJ) based separation control of flow past a NACA-0018 (National Advisory Committee for Aeronautics) airfoil, at 10° angle of attack and Reynolds number 104 based on the airfoil chord length C and uniform inflow velocity U0. The actuator of the SJ is modeled as a spanwise slot on the airfoil leeward surface and is placed just upstream of the leading edge separation position of the uncontrolled flow. The momentum coefficient of the SJ is chosen at a small value 2.13 × 10-4 normalized by that of the inflow. Three forcing frequencies are chosen for the present investigation: the low frequency (LF) F+ = feC/U0 = 0.5, the medium frequency (MF) F+ = 1.0, and the high frequency (HF) F+ = 4.0. We quantify the effects of forcing frequency for each case on the separation control and related vortex dynamics patterns. The simulations are performed using an energy conservative fourth-order parallel code. Numerical results reveal that the geometric variation introduced by the actuator has negligible effects on the mean flow field and the leading edge separation pattern; thus, the separation control effects are attributed to the SJ. The aerodynamic performances of the airfoil, characterized by lift and lift-to-drag ratio, are improved for all controlled cases, with the F+ = 1.0 case being the optimal one. The flow in the shear layer close to the actuator is locked to the jet, while in the wake this lock-in is maintained for the MF case but suppressed by the increasing turbulent fluctuations in the LF and HF cases. The vortex evolution downstream of the actuator presents two modes depending on the frequency: the vortex fragmentation and merging mode in the LF case where the vortex formed due to the SJ breaks up into several vortices and the latter merge as convecting downstream; the discrete vortices mode in the HF case where discrete vortices form and convect downstream without any fragmentation and merging

  11. Frequency of sternal foramen evaluated by MDCT: a minor variation of great relevance.

    PubMed

    Babinski, Marcio A; de Lemos, Leandro; Babinski, Monique S D; Gonçalves, Marianna V T; De Paula, Rafael C; Fernandes, Rodrigo M P

    2015-04-01

    Due to inadvertent cardiac or great vessel injury, sternal foramina may pose as a great hazard during sternal puncture. They can also be misinterpreted as osteolytic lesions in cross-sectional imaging of the sternum. The distribution of these variations differs between populations, but data from Brazilians are scarcely reported. Therefore, this study aimed to verify the frequency of midline sternal foramen and double-ended xiphoid process, as developmental variations, in order to avoid fatal complications following sternal puncture of sternal acupuncture treatment. A total of 114 chest computed tomograms were evaluated. The frequency of midline sternal foramen in a complication risk bearing feature is of approximately 10.5%. The double-ended xiphoid process was present in 17.5%. We conclude that sternal acupuncture should be planned in the region of corpus-previous CT should be done to rule out this variation. Furthermore, we strongly recommend the acupuncture technique which prescribes a safe superficial-oblique approach to the sternum. PMID:25023390

  12. Ecological drivers of variation in tool-use frequency across sea otter populations

    USGS Publications Warehouse

    Fujii, Jessica A; Ralls, Katherine; Tinker, M. Tim

    2015-01-01

    Sea otters are well-known tool users, employing objects such as rocks or shells to break open hard-shelled invertebrate prey. However, little is known about how the frequency of tool use varies among sea otter populations and the factors that drive these differences. We examined 17 years of observational data on prey capture and tool use from 8 sea otter populations ranging from southern California to the Aleutian Islands in Alaska. There were significant differences in the diets of these populations as well as variation in the frequency of tool use. Sea otters at Amchitka Island, Alaska, used tools on less than 1% of dives that resulted in the capture of prey compared with approximately 16% in Monterey, California. The percentage of individuals in the population that used tools ranged from 10% to 93%. In all populations, marine snails and thick-shelled bivalves were most likely to be associated with tool use, whereas soft-bodied prey items such as worms and sea stars were the least likely. The probability that a tool would be used on a given prey type varied across populations. The morphology of the prey item being handled and the prevalence of various types of prey in local diets were major ecological drivers of tool use: together they accounted for about 64% of the variation in tool-use frequency among populations. The remaining variation may be related to changes in the relative costs and benefits to an individual otter of learning to use tools effectively under differing ecological circumstances.

  13. Seasonal and Regional Variations of U.S. Trends in Extreme Precipitation Frequency

    NASA Astrophysics Data System (ADS)

    Kunkel, K. E.; Krisotovich, D.; Smith, R.; Ensor, L.; Easterling, D.

    2008-12-01

    Numerous studies have documented increases in U.S. heavy precipitation during the latter part of the 20th Century. Recent studies have also revealed that event frequencies were quite high early in the 20th Century, nearly as high as in the 1980s and 1990s. This suggests that natural variability may be quite large and perhaps the recent increases in the U.S. have a large natural component. The meteorological reasons behind the observed major decadal-scale variations in heavy precipitation have not been investigated. Have there been secular changes in the frequency, intensity, and other characteristics of the meteorological phenomena producing heavy precipitation? Can we attribute these changes to hemispheric or global trends in circulation, SSTs, etc.? Are the recent increases primarily a result of increases in atmospheric water vapor concentrations? Heavy precipitation events occur in a variety of meteorological situations/types that are seasonally and regionally variable. The seasonal and regional differences in trends can provide important insights into possible causes of decadal-scale variations in the frequency and intensity of extreme events. An investigation of such variations has revealed that in those cases where regional monthly trends are statistically significant, the trends are overwhelmingly upward. The great majority of these statistically significant upward monthly trends occur in the warm season (May-October), with the most widespread increases occurring in August. The central part of the U.S. from the Gulf Coast northward into the Great Lakes in particular has experienced statistically significant increases in many warm season months. The timing and locations of the observed increases suggest that a variety of phenomena could be contributing, including tropical cyclones, mesoscale convective systems, extratropical cyclones, and increased water vapor transport from the Gulf of Mexico/western Atlantic. More detailed investigation is required to

  14. Origin of terminal voltage variations due to self-mixing in terahertz frequency quantum cascade lasers.

    PubMed

    Grier, Andrew; Dean, Paul; Valavanis, Alexander; Keeley, James; Kundu, Iman; Cooper, Jonathan D; Agnew, Gary; Taimre, Thomas; Lim, Yah Leng; Bertling, Karl; Rakić, Aleksandar D; Li, Lianhe H; Harrison, Paul; Linfield, Edmund H; Ikonić, Zoran; Davies, A Giles; Indjin, Dragan

    2016-09-19

    We explain the origin of voltage variations due to self-mixing in a terahertz (THz) frequency quantum cascade laser (QCL) using an extended density matrix (DM) approach. Our DM model allows calculation of both the current-voltage (I-V) and optical power characteristics of the QCL under optical feedback by changing the cavity loss, to which the gain of the active region is clamped. The variation of intra-cavity field strength necessary to achieve gain clamping, and the corresponding change in bias required to maintain a constant current density through the heterostructure is then calculated. Strong enhancement of the self-mixing voltage signal due to non-linearity of the (I-V) characteristics is predicted and confirmed experimentally in an exemplar 2.6 THz bound-to-continuum QCL.

  15. Origin of terminal voltage variations due to self-mixing in terahertz frequency quantum cascade lasers.

    PubMed

    Grier, Andrew; Dean, Paul; Valavanis, Alexander; Keeley, James; Kundu, Iman; Cooper, Jonathan D; Agnew, Gary; Taimre, Thomas; Lim, Yah Leng; Bertling, Karl; Rakić, Aleksandar D; Li, Lianhe H; Harrison, Paul; Linfield, Edmund H; Ikonić, Zoran; Davies, A Giles; Indjin, Dragan

    2016-09-19

    We explain the origin of voltage variations due to self-mixing in a terahertz (THz) frequency quantum cascade laser (QCL) using an extended density matrix (DM) approach. Our DM model allows calculation of both the current-voltage (I-V) and optical power characteristics of the QCL under optical feedback by changing the cavity loss, to which the gain of the active region is clamped. The variation of intra-cavity field strength necessary to achieve gain clamping, and the corresponding change in bias required to maintain a constant current density through the heterostructure is then calculated. Strong enhancement of the self-mixing voltage signal due to non-linearity of the (I-V) characteristics is predicted and confirmed experimentally in an exemplar 2.6 THz bound-to-continuum QCL. PMID:27661929

  16. Variations in fundamental frequency peak position in Japanese macaque (Macaca fuscata) coo calls.

    PubMed

    Owren, M J; Casale, T M

    1994-09-01

    Japanese macaques (Macaca fuscata) produce coo calls whose use in various contexts is correlated with differences in the relative temporal position of the peak value of a call's fundamental frequency (Green, 1975). Studies have produced conflicting results about both the location of the category boundary between smooth early high and smooth late high coo subtypes and macaques' perceptual sensitivity to variations in peak position. In this study, fundamental frequency peak positions were measured in 578 coos produced by 8 captive adult female Japanese macaques in order to test whether calls with peak positions close to either of 2 hypothesized boundaries occurred at low rates. Overall, such calls were found to occur at rate equal to or higher than predicted by chance. Peak position varied more consistently between animals than by behavioral context. The results may indicate that peak position in coos does not form 2 distinct categories.

  17. Variation in drug injection frequency among out-of-treatment drug users in a national sample.

    PubMed

    Singer, M; Himmelgreen, D; Dushay, R; Weeks, M R

    1998-05-01

    This article analyzes data on drug injection frequency in a sample of more than 13,000 out-of-treatment drug injectors interviewed across 21 U.S. cities and Puerto Rico through the National Institute on Drug Abuse (NIDA) Cooperative Agreement for AIDS Community-Based Outreach/Intervention Research Program. The goals of the article are to present findings on injection frequency and to predict variation in terms of a set of variables suggested by previous research, including location, ethnicity, gender, age, educational attainment, years since first use of alcohol and marijuana, income, living arrangement, homelessness, drugs injected, and duration of injection across drugs. Three models were tested. Significant intersite differences were identified in injection frequency, although most of the other predictor variables we tested accounted for little of the variance. Ethnicity and drugs injected, however, were found to be significant. Taken together, location, ethnicity, and type of drug injected provide a configuration that differentiated and (for the variables available for the analysis) best predicted injection frequency. The public health implications of these findings are presented.

  18. Active noise control using noise source having adaptive resonant frequency tuning through stiffness variation

    NASA Technical Reports Server (NTRS)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor); Renshaw, Anthony A. (Inventor); Hedeen, Robert A. (Inventor)

    1995-01-01

    A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by a plurality of force transmitting mechanisms which contact the noise radiating element. Each one of the force transmitting mechanisms includes an expandable element and a spring in contact with the noise radiating element so that excitation of the element varies the spring force applied to the noise radiating element. The elements are actuated by a controller which receives input of a signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the elements and causes the spring force applied to the noise radiating element to be varied. The force transmitting mechanisms can be arranged to either produce bending or linear stiffness variations in the noise radiating element.

  19. Vertical normal modes of human ears: Individual variation and frequency estimation from pinna anthropometry.

    PubMed

    Mokhtari, Parham; Takemoto, Hironori; Nishimura, Ryouichi; Kato, Hiroaki

    2016-08-01

    Beyond the first peak of head-related transfer functions or pinna-related transfer functions (PRTFs) human pinnae are known to have two normal modes with "vertical" resonance patterns, involving two or three pressure anti-nodes in cavum, cymba, and fossa. However, little is known about individual variations in these modes, and there is no established model for estimating their center-frequencies from anthropometry. Here, with geometries of 38 pinnae measured, PRTFs were calculated and vertical modes visualized by numerical simulation. Most pinnae were found to have both Cavum-Fossa and Cavum-Cymba modes, with opposite-phase anti-nodes in cavum and either fossa or cymba, respectively. Nevertheless in both modes, fossa involvement varied substantially across pinnae, dependent on scaphoid fossa depth and cymba shallowness. Linear regression models were evaluated in mode frequency estimation, with 3322 measures derived from 31 pinna landmarks. The Cavum-Fossa normal mode frequency was best estimated [correlation coefficient r = 0.89, mean absolute error (MAE) = 257 Hz or 4.4%] by the distance from canal entrance to helix rim, and cymba horizontal depth. The Cavum-Cymba normal mode frequency was best estimated (r = 0.92, MAE = 247 Hz or 3.2%) by the sagittal-plane distance from concha floor to cymba anterior wall, and cavum horizontal depth. PMID:27586714

  20. Denoising of Ictal EEG Data Using Semi-Blind Source Separation Methods Based on Time-Frequency Priors.

    PubMed

    Hajipour Sardouie, Sepideh; Bagher Shamsollahi, Mohammad; Albera, Laurent; Merlet, Isabelle

    2015-05-01

    Removing muscle activity from ictal ElectroEncephaloGram (EEG) data is an essential preprocessing step in diagnosis and study of epileptic disorders. Indeed, at the very beginning of seizures, ictal EEG has a low amplitude and its morphology in the time domain is quite similar to muscular activity. Contrary to the time domain, ictal signals have specific characteristics in the time-frequency domain. In this paper, we use the time-frequency signature of ictal discharges as a priori information on the sources of interest. To extract the time-frequency signature of ictal sources, we use the Canonical Correlation Analysis (CCA) method. Then, we propose two time-frequency based semi-blind source separation approaches, namely the Time-Frequency-Generalized EigenValue Decomposition (TF-GEVD) and the Time-Frequency-Denoising Source Separation (TF-DSS), for the denoising of ictal signals based on these time-frequency signatures. The performance of the proposed methods is compared with that of CCA and Independent Component Analysis (ICA) approaches for the denoising of simulated ictal EEGs and of real ictal data. The results show the superiority of the proposed methods in comparison with CCA and ICA. PMID:25095269

  1. Developments in FINDbase worldwide database for clinically relevant genomic variation allele frequencies.

    PubMed

    Papadopoulos, Petros; Viennas, Emmanouil; Gkantouna, Vassiliki; Pavlidis, Cristiana; Bartsakoulia, Marina; Ioannou, Zafeiria-Marina; Ratbi, Ilham; Sefiani, Abdelaziz; Tsaknakis, John; Poulas, Konstantinos; Tzimas, Giannis; Patrinos, George P

    2014-01-01

    FINDbase (http://www.findbase.org) aims to document frequencies of clinically relevant genomic variations, namely causative mutations and pharmacogenomic markers, worldwide. Each database record includes the population, ethnic group or geographical region, the disorder name and the related gene, accompanied by links to any related databases and the genetic variation together with its frequency in that population. Here, we report, in addition to the regular data content updates, significant developments in FINDbase, related to data visualization and querying, data submission, interrelation with other resources and a new module for genetic disease summaries. In particular, (i) we have developed new data visualization tools that facilitate data querying and comparison among different populations, (ii) we have generated a new FINDbase module, built around Microsoft's PivotViewer (http://www.getpivot.com) software, based on Microsoft Silverlight technology (http://www.silverlight.net), that includes 259 genetic disease summaries from five populations, systematically collected from the literature representing the documented genetic makeup of these populations and (iii) the implementation of a generic data submission tool for every module currently available in FINDbase.

  2. Wolbachia in European Populations of the Invasive Pest Drosophila suzukii: Regional Variation in Infection Frequencies

    PubMed Central

    Gibert, Patricia; Martinez, Julien; Fraimout, Antoine; Jiggins, Francis; Andrieux, Thibault; Siozios, Stefanos; Anfora, Gianfranco; Miller, Wolfgang; Rota-Stabelli, Omar; Mouton, Laurence

    2016-01-01

    The invasive pest Drosophila suzukii is characterized by a specific fresh-fruit targeting behavior and has quickly become a menace for the fruit economy of newly infested North American and European regions. D. suzukii carries a strain of the endosymbiotic bacterium Wolbachia, named wSuz, which has a low infection frequency and no reproductive manipulation capabilities in American populations of D. suzukii. To further understand the nature of wSuz biology and assess its utility as a tool for controlling this pest’s populations, we investigated the prevalence of Wolbachia in 23 European D. suzukii populations, and compared our results with those available in American populations. Our data showed a highly variable infection frequency with a mean prevalence of 46%, which is significantly higher than the 17% found in American populations. Based on Multilocus Sequence Typing analysis, a single wSuz strain was diagnosed in all European populations of D. suzukii. In agreement with American data, we found no evidence of cytoplasmic incompatibility induced by wSuz. These findings raise two questions: a) why Wolbachia is maintained in field populations of D. suzukii and b) what are the selective forces responsible for the variation in prevalence within populations, particularly between European and American continents? Our results provide new insights into the D. suzukii-Wolbachia association and highlight regional variations that await further investigation and that should be taken into account for using Wolbachia-based pest management programs. PMID:26809119

  3. A comparison of intrasubject variation across sessions of three vocal frequency perturbation indices.

    PubMed

    Higgins, M B; Saxman, J H

    1989-09-01

    Within-subject variation of three vocal frequency perturbation indices was compared across multiple sessions. The magnitude of jitter factor (JF), pitch perturbation quotient (PPQ), and directional perturbation quotient (DPF) was measured every other day for 33 consecutive days for ten female and five male normal young adult speakers. Perturbation measures were calculated using a zero-crossing analysis of taped [i] and [u] productions. Pearson product-moment correlations among the three perturbation indices were calculated to examine their relation over time. Coefficients of variation for JF, PPQ, and DPF were considered indicative of the temporal stability of the three measures. JF and PPQ provided redundant information about laryngeal behaviors in steady-state productions. DPF, however, appeared to measure different laryngeal behaviors. Also, JF and PPQ varied considerably within individuals across sessions while DPF was the more temporally stable measure. Multiple sampling sessions and measurement of both the magnitude and direction of period differences are advised for future investigations of vocal frequency perturbation.

  4. Variation in the human lymphocyte sister chromatid exchange frequency as a function of time: results of daily and twice-weekly sampling

    SciTech Connect

    Tucker, J.D.; Christensen, M.L.; Strout, C.L.; McGee, K.A.; Carrano, A.V.

    1987-01-01

    The variation in lymphocyte sister chromatid exchange (SCE) frequency was investigated in healthy nonsmokers who were not taking any medication. Two separate studies were undertaken. In the first, blood was drawn from four women twice a week for 8 weeks. These donors recorded the onset and termination of menstruation and times of illness. In the second study, blood was obtained from two women and two men for 5 consecutive days on two separate occasions initiated 14 days apart. Analysis of the mean SCE frequencies in each study indicated that significant temporal variation occurred in each donor, and that more variation occurred in the longer study. Some of the variation was found to be associated with the menstrual cycle. In the daily study, most of the variation appeared to be random, but occasional day-to-day changes occurred that were greater than those expected by chance. To determine how well a single SCE sample estimated the pooled mean for each donor in each study, the authors calculated the number of samples that encompassed that donor's pooled mean within 1 or more standard errors. For both studies, about 75% of the samples encompassed the pooled mean within 2 standard errors. An analysis of high-frequency cells (HFCs) was also undertaken. The results for each study indicate that the proportion of HFCs, compared with the use of Fisher's Exact test, is significantly more constant than the means, which were compared by using the t-test. These results coupled with our previous work suggest that HFC analysis may be the method of choice when analyzing data from human population studies.

  5. Regional frequency analysis to asses wind resource spatial and temporal variations in Washington State

    NASA Astrophysics Data System (ADS)

    Mortuza, M.; Demissie, D.

    2013-12-01

    According to the U.S. Department of Energy's annual wind technologies market report, the wind power capacity in the country grew from 2.5 gigawatts in early 2000 to 60 gigawatts in 2012, making it one of the largest new sources of electric capacity additions in the U.S. in recent years. With over 2.8 gigawatts of current capacity (eighth largest in the nation), Washington State plays a significant role in this rapidly increasing energy resource. To further expand and/or optimize these capacities, assessment of wind resource and its spatial and temporal variations are important. However, since at-site frequency analysis using meteorological data is not adequate for extending wind frequency to locations with no data, longer return period, and heterogeneous topography and surface, a regional frequency analysis based on L-moment method is adopted in this study to estimate regional wind speed patterns and return periods in Washington State using hourly mean wind speed data from 1979 - 2010. The analysis applies the k-means, hierarchical and self-organizing map clustering techniques to explore potential clusters or regions; statistical tests are then applied to identify homogeneous regions and appropriate probability distribution models. The result from the analysis is expected to provide essential knowledge about the areas with potential capacity of constructing wind power plants, which can also be readily extended to assist decisions on their daily operations.

  6. Examining Spatio-Temporal Intensity-Frequency Variations in Extreme Monsoon Rainfall using High Resolution Data

    NASA Astrophysics Data System (ADS)

    Devak, M.; Rajendran, V.; C T, D.

    2015-12-01

    The study of extreme events has gained the attention of hydrologists in recent times. Though these events are rare, the effects are catastrophic. It is reported that the frequency of the occurrence of these events has increased in recent decades, and is attributed to the recent revelation of climate change. Numerous studies have pointed out significant changes in extremely heavy precipitation over India, using coarse resolution data. Though there are disagreements in the results and its spatial uniformity, all these studies emphasize the need of fine resolution analysis. Fine resolution analysis is necessary mainly due to the highly heterogeneous characteristics of Indian monsoon, and for the proper employment in flood hazard preparedness and water resources management. The present study aims to analyse the spatio-temporal variation and trends in the intensity and frequency of heavy precipitation during Indian monsoon using 0.25°×0.25° resolution gridded data for a period of 113 years (1901-2013). The exceedance threshold is fixed at 90th percentile of rainfall over 113 years and parameters are defined accordingly. The maximum intensity of each extreme rainfall episode of 30 year moving window has been modelled using Peak Over Threshold based Extreme Value Theory to compute return level (considered for intensity). In addition, the number of such episodes in a particular year has been termed as frequency. Non-parametric Mann-Kendall test has been carried out for both intensity and frequency, to compute the statistical trend. In addition, moving block bootstrap approach has been used to incorporate the serial correlation. The significance of the trend has been evaluated at different significance levels and finally, change in trend over last century has been examined.

  7. High-frequency alternating-crossed-field gel electrophoresis with neutral or slightly charged interpenetrating networks to improve DNA separation.

    PubMed

    Boyd, B M; Prausnitz, J M; Blanch, H W

    1998-12-01

    Toward improving DNA separations, this work reports the effects of high-frequency square-wave AC fields superimposed perpendicular to the direct current (DC) separation field on DNA migration in both polyacrylamide-based interpenetrating networks (IPNs) and in agarose networks. Compared to standard polyacrylamide gels, IPNs allow the separation of larger DNA (9000 bp vs. 5000 bp at 5 V/cm). In novel polyacrylamide-based IPNs, an alternating current (AC) field of 5 Hz increased the maximum DNA size separable. This effect was extended to larger DNA sizes with increasing electric-field strength up to and apparently beyond the power supply-limited maximum electric-field strength of 48 V/cm. The orthogonal AC field also increased mobility. These two results combine to yield a reduction in separation time of up to a factor of 20 in novel polyacrylamide-based IPNs. When negatively charged acrylic-acid groups were incorporated into the IPNs, the use of the AC field changed the DNA-network interaction, which altered the size dependence of DNA mobility. In agarose gels, an AC field of 50 Hz increased the size range separable; however, there was no increase in DNA mobility. There was no change in size dependence of mobility in an AC field when the number of charged groups in the agarose network was increased. Based on results in the literature, possible mechanisms were examined for the effects of the AC field on DNA separation.

  8. High-frequency Earth rotation variations deduced from altimetry-based ocean tides

    NASA Astrophysics Data System (ADS)

    Madzak, Matthias; Schindelegger, Michael; Böhm, Johannes; Bosch, Wolfgang; Hagedoorn, Jan

    2016-06-01

    A model of diurnal and semi-diurnal variations in Earth rotation parameters (ERP) is constructed based on altimetry-measured tidal heights from a multi-mission empirical ocean tide solution. Barotropic currents contributing to relative angular momentum changes are estimated for nine major tides in a global inversion algorithm that solves the two-dimensional momentum equations on a regular 0.5° grid with a heavily weighted continuity constraint. The influence of 19 minor tides is accounted for by linear admittance interpolation of ocean tidal angular momentum, although the assumption of smooth admittance variations with frequency appears to be a doubtful concept for semi-diurnal mass terms in particular. A validation of the newly derived model based on post-fit corrections to polar motion and universal time (Δ UT1) from the analysis of Very Long Baseline Interferometry (VLBI) observations shows a variance reduction for semi-diurnal Δ UT1 residuals that is significant at the 0.05 level with respect to the conventional ERP model. Improvements are also evident for the explicitly modeled K_1 , Q_1 , and K_2 tides in individual ERP components, but large residuals of more than 15 μ as remain at the principal lunar frequencies of O_1 and M_2 . We attribute these shortcomings to uncertainties in the inverted relative angular momentum changes and, to a minor extent, to violation of mass conservation in the empirical ocean tide solution. Further dedicated hydrodynamic modeling efforts of these anomalous constituents are required to meet the accuracy standards of modern space geodesy.

  9. High-frequency Earth rotation variations deduced from altimetry-based ocean tides

    NASA Astrophysics Data System (ADS)

    Madzak, Matthias; Schindelegger, Michael; Böhm, Johannes; Bosch, Wolfgang; Hagedoorn, Jan

    2016-11-01

    A model of diurnal and semi-diurnal variations in Earth rotation parameters (ERP) is constructed based on altimetry-measured tidal heights from a multi-mission empirical ocean tide solution. Barotropic currents contributing to relative angular momentum changes are estimated for nine major tides in a global inversion algorithm that solves the two-dimensional momentum equations on a regular 0.5° grid with a heavily weighted continuity constraint. The influence of 19 minor tides is accounted for by linear admittance interpolation of ocean tidal angular momentum, although the assumption of smooth admittance variations with frequency appears to be a doubtful concept for semi-diurnal mass terms in particular. A validation of the newly derived model based on post-fit corrections to polar motion and universal time (Δ UT1) from the analysis of Very Long Baseline Interferometry (VLBI) observations shows a variance reduction for semi-diurnal Δ UT1 residuals that is significant at the 0.05 level with respect to the conventional ERP model. Improvements are also evident for the explicitly modeled K_1, Q_1, and K_2 tides in individual ERP components, but large residuals of more than 15 μ as remain at the principal lunar frequencies of O_1 and M_2. We attribute these shortcomings to uncertainties in the inverted relative angular momentum changes and, to a minor extent, to violation of mass conservation in the empirical ocean tide solution. Further dedicated hydrodynamic modeling efforts of these anomalous constituents are required to meet the accuracy standards of modern space geodesy.

  10. Extreme Recombination Frequencies Shape Genome Variation and Evolution in the Honeybee, Apis mellifera

    PubMed Central

    Wallberg, Andreas; Glémin, Sylvain; Webster, Matthew T.

    2015-01-01

    Meiotic recombination is a fundamental cellular process, with important consequences for evolution and genome integrity. However, we know little about how recombination rates vary across the genomes of most species and the molecular and evolutionary determinants of this variation. The honeybee, Apis mellifera, has extremely high rates of meiotic recombination, although the evolutionary causes and consequences of this are unclear. Here we use patterns of linkage disequilibrium in whole genome resequencing data from 30 diploid honeybees to construct a fine-scale map of rates of crossing over in the genome. We find that, in contrast to vertebrate genomes, the recombination landscape is not strongly punctate. Crossover rates strongly correlate with levels of genetic variation, but not divergence, which indicates a pervasive impact of selection on the genome. Germ-line methylated genes have reduced crossover rate, which could indicate a role of methylation in suppressing recombination. Controlling for the effects of methylation, we do not infer a strong association between gene expression patterns and recombination. The site frequency spectrum is strongly skewed from neutral expectations in honeybees: rare variants are dominated by AT-biased mutations, whereas GC-biased mutations are found at higher frequencies, indicative of a major influence of GC-biased gene conversion (gBGC), which we infer to generate an allele fixation bias 5 – 50 times the genomic average estimated in humans. We uncover further evidence that this repair bias specifically affects transitions and favours fixation of CpG sites. Recombination, via gBGC, therefore appears to have profound consequences on genome evolution in honeybees and interferes with the process of natural selection. These findings have important implications for our understanding of the forces driving molecular evolution. PMID:25902173

  11. Nickel-silica nanocomposite: Variation of the blocking temperature with magnetic field and measuring frequency

    NASA Astrophysics Data System (ADS)

    Singh, V.; Seehra, M. S.; Bonevich, J.

    2008-04-01

    The variations of the blocking temperature TB with measuring frequency fm and applied field H are reported for Ni nanoparticles (NPs) embedded in SiO2 matrix with the nominal composition Ni /SiO2 (15/85). Transmission electron microscopy of the sol-gel prepared NPs yielded a log-normal distribution with diameter D =3.8(0.2)nm whereas x-ray diffraction data yielded D ≃3.3nm. The TB versus fm variation for fm=0.1-1000Hz fits the equation TB=Ta/ln(f0/fm) with f0=2.6×109Hz and Ta=270K whereas TB versus H data follows the equation TB(H)=33(1-H/H0)m with H0=3200Oe and m =2(3/2) for lower (higher) H. These results are compared with the predictions of the Néel-Brown model of magnetic relaxation in noninteracting NPs.

  12. Variation in humpback whale (Megaptera novaeangliae) song length in relation to low-frequency sound broadcasts.

    PubMed

    Fristrup, Kurt M; Hatch, Leila T; Clark, Christopher W

    2003-06-01

    Humpback whale song lengths were measured from recordings made off the west coast of the island of Hawai'i in March 1998 in relation to acoustic broadcasts ("pings") from the U.S. Navy SURTASS Low Frequency Active sonar system. Generalized additive models were used to investigate the relationships between song length and time of year, time of day, and broadcast factors. There were significant seasonal and diurnal effects. The seasonal factor was associated with changes in the density of whales sighted near shore. The diurnal factor was associated with changes in surface social activity. Songs that ended within a few minutes of the most recent ping tended to be longer than songs sung during control periods. Many songs that were overlapped by pings, and songs that ended several minutes after the most recent ping, did not differ from songs sung in control periods. The longest songs were sung between 1 and 2 h after the last ping. Humpbacks responded to louder broadcasts with longer songs. The fraction of variation in song length that could be attributed to broadcast factors was low. Much of the variation in humpback song length remains unexplained.

  13. Demeter/ICE Experiment: Study of low frequency transmitter intensity variations

    NASA Astrophysics Data System (ADS)

    Boudjada, M. Y.; Moldovan, I.; Schwingenschuh, K.; Al-Haddad, E.; Biagi, P. F.; Parrot, M.

    2012-04-01

    We report on low frequency (LF) transmitter signal recorded by the 'Instrument Capteur Electrique' (ICE) experiment onboard the DEMETER micro-satellite. We mainly consider the signal emitted by the Brasov broadcasting station (25.60E, 45.75N) at frequency of about 153 kHz. We analyze the reception conditions of this transmitter several weeks before the occurrence of the Vrancea earthquakes, on October, 27th, 2004. Ground-based observations revealed the presence of sudden decrease of the Y-component of the magnetic field at Muntele Rosu Observatory (Romania), at about 68 km from the epicenter, as reported by Moldovan et al. (Rom. Journ. Phys., Vol. 54, Nos. 1-2, p. 249-261, Bucharest, 2009). In this contribution we attempt to check if the LF Brasov signal was also subject to similar disturbances as observed by the ground-station. We focus on the variation of the LF transmitter intensity levels, several weeks before and after the Vrancea earthquake occurrence. We discuss the physical parameters which may disturb the signal reception in particular the geomagnetic activity and the signal to noise ratios.

  14. High-Frequency Variation of Purine Biosynthesis Genes Is a Mechanism of Success in Campylobacter jejuni

    PubMed Central

    Cameron, Andrew; Huynh, Steven; Scott, Nichollas E.; Frirdich, Emilisa; Apel, Dmitry; Foster, Leonard J.; Parker, Craig T.

    2015-01-01

    ABSTRACT Phenotypic variation is prevalent in the zoonotic pathogen Campylobacter jejuni, the leading agent of enterocolitis in the developed world. Heterogeneity enhances the survival and adaptive malleability of bacterial populations because variable phenotypes may allow some cells to be protected against future stress. Exposure to hyperosmotic stress previously revealed prevalent differences in growth between C. jejuni strain 81-176 colonies due to resistant or sensitive phenotypes, and these isolated colonies continued to produce progeny with differential phenotypes. In this study, whole-genome sequencing of isolated colonies identified allelic variants of two purine biosynthesis genes, purF and apt, encoding phosphoribosyltransferases that utilize a shared substrate. Genetic analyses determined that purF was essential for fitness, while apt was critical. Traditional and high-depth amplicon-sequencing analyses confirmed extensive intrapopulation genetic variation of purF and apt that resulted in viable strains bearing alleles with in-frame insertion duplications, deletions, or missense polymorphisms. Different purF and apt alleles were associated with various stress survival capabilities under several niche-relevant conditions and contributed to differential intracellular survival in an epithelial cell infection model. Amplicon sequencing revealed that intracellular survival selected for stress-fit purF and apt alleles, as did exposure to oxygen and hyperosmotic stress. Putative protein recognition direct repeat sequences were identified in purF and apt, and a DNA-protein affinity screen captured a predicted exonuclease that promoted the global spontaneous mutation rate. This work illustrates the adaptive properties of high-frequency genetic variation in two housekeeping genes, which influences C. jejuni survival under stress and promotes its success as a pathogen. PMID:26419875

  15. Hydrological niche separation explains seasonal and inter-annual variations of vegetation dynamics in seasonally dry tropical forests

    NASA Astrophysics Data System (ADS)

    Xu, X.; Medvigy, D.; Powers, J. S.; Becknell, J. M.; Guan, K.

    2015-12-01

    Despite ample water supply, vegetation dynamics are subject to seasonal water stress in large fraction of tropical forests. These seasonally dry tropical forests (SDTFs) account for over 40% of tropical forests, harbor high biodiversity, have large potential carbon sink due to forest recovery from human disturbance and also play a critical role in global carbon budget and inter-annual variations. Plants in this biome display notably diverse responses to seasonal and inter-annual variations of water availability, especially inter-specific variations in canopy seasonality and biomass growth. Current process-based dynamic vegetation models cannot represent these diversities and are shown to perform poorly on simulating drought responses of tropical forests, calling into question of their ability to accurately simulate future changes in SDTFs. Accumulated field observations, suggest that hydrological niche separation driven by coordinated plant functional traits is associated with plants' performance under drought. Yet, it remains not clear whether the physiology-level hydrological niche separation can explain the ecosystem-level diversity observed in SDTFs. Here, we test the theory with a model-data fusion approach. We implemented a new plant hydrodynamic module that is able to track leaf water potential at sub-daily scale in ED2 model. We further incorporated a hydrological niche separation scheme based on a meta-data analysis of key functional traits in SDTFs. Simulated ecological patterns with and without hydrological niche separation were then compared with remote-sensing and long-term field observations from an SDTF site in Palo Verde, Costa Rica. Using several numerical experiments, we specifically examine the following questions: (i) Whether hydrological niche separation can explain the diversity in canopy seasonality and biomass growth? (ii) How important are the yet uncertain belowground functional traits, especially root profile in determining canopy

  16. Ethnic Variations in the Connection between Work-Induced Family Separation and Turnover Intent

    ERIC Educational Resources Information Center

    Behnke, Andrew O.; MacDermid, Shelley M.; Anderson, James C.; Weiss, Howard M.

    2010-01-01

    Using conservation of resources theory, this study examines the role of resources in the relationship between work-induced family separation and workers' intentions to leave their employment and how these relationships vary across ethnic groups. Analyses of a large representative sample of military members reveal that family separation is…

  17. PERIODIC VARIATIONS IN THE O - C DIAGRAMS OF FIVE PULSATION FREQUENCIES OF THE DB WHITE DWARF EC 20058-5234

    SciTech Connect

    Dalessio, J.; Provencal, J. L.; Shipman, H. L.; Sullivan, D. J.; Sullivan, T.; Kilkenny, D.; Fraga, L.; Sefako, R.

    2013-03-01

    Variations in the pulsation arrival time of five independent pulsation frequencies of the DB white dwarf EC 20058-5234 individually imitate the effects of reflex motion induced by a planet or companion but are inconsistent when considered in unison. The pulsation frequencies vary periodically in a 12.9 year cycle and undergo secular changes that are inconsistent with simple neutrino plus photon-cooling models. The magnitude of the periodic and secular variations increases with the period of the pulsations, possibly hinting that the corresponding physical mechanism is located near the surface of the star. The phase of the periodic variations appears coupled to the sign of the secular variations. The standards for pulsation-timing-based detection of planetary companions around pulsating white dwarfs, and possibly other variables such as subdwarf B stars, should be re-evaluated. The physical mechanism responsible for this surprising result may involve a redistribution of angular momentum or a magnetic cycle. Additionally, variations in a supposed combination frequency are shown to match the sum of the variations of the parent frequencies to remarkable precision, an expected but unprecedented confirmation of theoretical predictions.

  18. Periodic Variations in the O - C Diagrams of Five Pulsation Frequencies of the DB White Dwarf EC 20058-5234

    NASA Astrophysics Data System (ADS)

    Dalessio, J.; Sullivan, D. J.; Provencal, J. L.; Shipman, H. L.; Sullivan, T.; Kilkenny, D.; Fraga, L.; Sefako, R.

    2013-03-01

    Variations in the pulsation arrival time of five independent pulsation frequencies of the DB white dwarf EC 20058-5234 individually imitate the effects of reflex motion induced by a planet or companion but are inconsistent when considered in unison. The pulsation frequencies vary periodically in a 12.9 year cycle and undergo secular changes that are inconsistent with simple neutrino plus photon-cooling models. The magnitude of the periodic and secular variations increases with the period of the pulsations, possibly hinting that the corresponding physical mechanism is located near the surface of the star. The phase of the periodic variations appears coupled to the sign of the secular variations. The standards for pulsation-timing-based detection of planetary companions around pulsating white dwarfs, and possibly other variables such as subdwarf B stars, should be re-evaluated. The physical mechanism responsible for this surprising result may involve a redistribution of angular momentum or a magnetic cycle. Additionally, variations in a supposed combination frequency are shown to match the sum of the variations of the parent frequencies to remarkable precision, an expected but unprecedented confirmation of theoretical predictions. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the US National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

  19. The tRNA-Tyr gene family of Saccharomyces cerevisiae: agents of phenotypic variation and position effects on mutation frequency.

    PubMed Central

    Ito-Harashima, Sayoko; Hartzog, Phillip E; Sinha, Himanshu; McCusker, John H

    2002-01-01

    Extensive phenotypic diversity or variation exists in clonal populations of microorganisms and is thought to play a role in adaptation to novel environments. This phenotypic variation or instability, which occurs by multiple mechanisms, may be a form of cellular differentiation and a stochastic means for modulating gene expression. This work dissects a case of phenotypic variation in a clinically derived Saccharomyces cerevisiae strain involving a cox15 ochre mutation, which acts as a reporter. The ochre mutation reverts to sense at a low frequency while tRNA-Tyr ochre suppressors (SUP-o) arise at a very high frequency to produce this phenotypic variation. The SUP-o mutations are highly pleiotropic. In addition, although all SUP-o mutations within the eight-member tRNA-Tyr gene family suppress the ochre mutation reporter, there are considerable phenotypic differences among the different SUP-o mutants. Finally, and of particular interest, there is a strong position effect on mutation frequency within the eight-member tRNA-Tyr gene family, with one locus, SUP6, mutating at a much higher than average frequency and two other loci, SUP2 and SUP8, mutating at much lower than average frequencies. Mechanisms for the position effect on mutation frequency are evaluated. PMID:12196388

  20. Independent vector analysis based on overlapped cliques of variable width for frequency-domain blind signal separation

    NASA Astrophysics Data System (ADS)

    Lee, Intae; Jang, Gil-Jin

    2012-12-01

    A novel method is proposed to improve the performance of independent vector analysis (IVA) for blind signal separation of acoustic mixtures. IVA is a frequency-domain approach that successfully resolves the well-known permutation problem by applying a spherical dependency model to all pairs of frequency bins. The dependency model of IVA is equivalent to a single clique in an undirected graph; a clique in graph theory is defined as a subset of vertices in which any pair of vertices is connected by an undirected edge. Therefore, IVA imposes the same amount of statistical dependency on every pair of frequency bins, which may not match the characteristics of real-world signals. The proposed method allows variable amounts of statistical dependencies according to the correlation coefficients observed in real acoustic signals and, hence, enables more accurate modeling of statistical dependencies. A number of cliques constitutes the new dependency graph so that neighboring frequency bins are assigned to the same clique, while distant bins are assigned to different cliques. The permutation ambiguity is resolved by overlapped frequency bins between neighboring cliques. For speech signals, we observed especially strong correlations across neighboring frequency bins and a decrease in these correlations with an increase in the distance between bins. The clique sizes are either fixed, or determined by the reciprocal of the mel-frequency scale to impose a wider dependency on low-frequency components. Experimental results showed improved performances over conventional IVA. The signal-to-interference ratio improved from 15.5 to 18.8 dB on average for seven different source locations. When we varied the clique sizes according to the observed correlations, the stability of the proposed method increased with a large number of cliques.

  1. Dielectric properties of porcine cerebrospinal tissues at microwave frequencies: in vivo, in vitro and systematic variation with age

    NASA Astrophysics Data System (ADS)

    Peyman, A.; Holden, S. J.; Watts, S.; Perrott, R.; Gabriel, C.

    2007-04-01

    The dielectric properties of pig cerebrospinal tissues were measured in vivo and in vitro, in the frequency range of 50 MHz-20 GHz. The total combined measurement uncertainty was calculated at each frequency point and is reported over representative frequency regions. Comparisons were made for each tissue between the two sets of data and with the literature of the past decade. The in vitro study was extended to include tissue from pigs weighing approximately 10, 50 and 250 kg to re-visit the question of the variation of dielectric properties with age. White matter and spinal chord showed significant variation as function of animal age, no age-related variations were recorded for grey matter.

  2. Perceptual Qualities of Ethanol Depend on Concentration, and Variation in These Percepts Associates with Drinking Frequency

    PubMed Central

    Nolden, Alissa A.

    2016-01-01

    Introduction Ethanol, the pharmaceutically active ingredient in all alcoholic beverages, elicits multiple percepts including sweet, bitter, drying, and burning. However, quality-specific perceptual dose-response functions have not been previously reported. Also, individual differences in ethanol perception may associate with differences in alcoholic beverage use. Here, we describe the chemosensory profile of ethanol across concentrations in a convenience sample of mixed-age adults; secondarily, we explore whether individual differences in various qualities from ethanol associate with alcohol use behaviors. Methods Participants (n=100, 33 men) aged 21 to 55 (mean 33 years) tasted ethanol in water (4, 8, 16, 32, and 48 % v/v) and rated sweetness, bitterness, drying, and burning/tingling on four general Labeled Magnitude Scales. Demographic question and alcohol use measures (years drinking and reported frequency of drinking occasions) were also collected. Results Intensity of most qualities increased as a function of ethanol concentration, although the dominant sensation differed with concentration. The dominant sensation for 8 and 16 % ethanol was bitterness (7.4±1.0; 13.5±1.4), whereas for 32 and 48 % ethanol, burning/tingling was the dominant sensation (29.7±2.1; 44.7±2.4). Variation in quality-specific intensities of sampled ethanol explained variability in the reported intake frequency for beer, wine, straight spirits, and number of drinking occasions. The number of years reported drinking (grand mean 10.5±0.8) was not significantly associated with perceptual ratings for sampled ethanol. Conclusions In a convenience sample of mixed-aged adults, the sensations from suprathreshold ethanol varied by concentration: bitterness dominated at lower concentrations, while burn dominated at higher concentrations. Exploratory analyses also suggest that differences in chemosensory responses across participants may associate with measures of alcohol use.

  3. Process controls on regional flood frequency: Coefficient of variation and basin scale

    NASA Astrophysics Data System (ADS)

    BlöSchl, Günter; Sivapalan, Murugesu

    1997-12-01

    The coefficient of variation (CV) of maximum annual floods is examined to understand the effects of process controls and catchment size. A derived flood frequency model is used to interpret data from 489 catchments in Austria. At the core of process controls appears to be the interaction of catchment response time and storm duration, but the magnitude is not large, and often this interaction is hidden by other processes. The dependence of rainfall intensity and duration is clearly very important and reduces CV significantly. Increasing channel travel times with catchment scale tend to translate into decreasing CVs with area for small catchments while they tend to translate into increasing CVs with area for larger catchments. Nonlinear runoff processes, including threshold effects, is the main mechanism for increasing CV. They give rise to complex patterns in the relationship between CV and area. Base flow has been used as a surrogate for a number of processes, such as seasonality of streamflow. It always decreases CV and, in particular, leads to a significant decrease of CV with area. Both the observed tendency of CV to decrease with area and the scatter in the data are the result of a complex interplay of a number of processes which allows various alternative interpretations. Depending on which processes dominate under a particular hydrologic regime, different patterns arise. It appears that the explanations of the relationship between CV and catchment scale suggested in the literature are too simplistic. The case is made for using the concept of hydrologic regimes and process studies of the type presented here to help delineate homogeneous regions for regional flood frequency analyses in a physically consistent way.

  4. Perceptual Qualities of Ethanol Depend on Concentration, and Variation in These Percepts Associates with Drinking Frequency

    PubMed Central

    Nolden, Alissa A.

    2016-01-01

    Introduction Ethanol, the pharmaceutically active ingredient in all alcoholic beverages, elicits multiple percepts including sweet, bitter, drying, and burning. However, quality-specific perceptual dose-response functions have not been previously reported. Also, individual differences in ethanol perception may associate with differences in alcoholic beverage use. Here, we describe the chemosensory profile of ethanol across concentrations in a convenience sample of mixed-age adults; secondarily, we explore whether individual differences in various qualities from ethanol associate with alcohol use behaviors. Methods Participants (n=100, 33 men) aged 21 to 55 (mean 33 years) tasted ethanol in water (4, 8, 16, 32, and 48 % v/v) and rated sweetness, bitterness, drying, and burning/tingling on four general Labeled Magnitude Scales. Demographic question and alcohol use measures (years drinking and reported frequency of drinking occasions) were also collected. Results Intensity of most qualities increased as a function of ethanol concentration, although the dominant sensation differed with concentration. The dominant sensation for 8 and 16 % ethanol was bitterness (7.4±1.0; 13.5±1.4), whereas for 32 and 48 % ethanol, burning/tingling was the dominant sensation (29.7±2.1; 44.7±2.4). Variation in quality-specific intensities of sampled ethanol explained variability in the reported intake frequency for beer, wine, straight spirits, and number of drinking occasions. The number of years reported drinking (grand mean 10.5±0.8) was not significantly associated with perceptual ratings for sampled ethanol. Conclusions In a convenience sample of mixed-aged adults, the sensations from suprathreshold ethanol varied by concentration: bitterness dominated at lower concentrations, while burn dominated at higher concentrations. Exploratory analyses also suggest that differences in chemosensory responses across participants may associate with measures of alcohol use. PMID:27594968

  5. Maintaining acoustic communication at a cocktail party: heterospecific masking noise improves signal detection through frequency separation

    PubMed Central

    Siegert, M. E.; Römer, H.; Hartbauer, M.

    2014-01-01

    SUMMARY We examined acoustic masking in a chirping katydid species of the Mecopoda elongata complex due to interference with a sympatric Mecopoda species where males produce continuous trills at high amplitudes. Frequency spectra of both calling songs range from 1 to 80 kHz; the chirper species has more energy in a narrow frequency band at 2 kHz and above 40 kHz. Behaviourally, chirper males successfully phase-locked their chirps to playbacks of conspecific chirps under masking conditions at signal-to-noise ratios (SNRs) of −8 dB. After the 2 kHz band in the chirp had been equalised to the level in the masking trill, the breakdown of phase-locked synchrony occurred at a SNR of +7 dB. The remarkable receiver performance is partially mirrored in the selective response of a first-order auditory interneuron (TN1) to conspecific chirps under these masking conditions. However, the selective response is only maintained for a stimulus including the 2 kHz component, although this frequency band has no influence on the unmasked TN1 response. Remarkably, the addition of masking noise at 65 dB sound pressure level (SPL) to threshold response levels of TN1 for pure tones of 2 kHz enhanced the sensitivity of the response by 10 dB. Thus, the spectral dissimilarity between masker and signal at a rather low frequency appears to be of crucial importance for the ability of the chirping species to communicate under strong masking by the trilling species. We discuss the possible properties underlying the cellular/synaptic mechanisms of the ‘novelty detector’. PMID:24307713

  6. Seasonal Variation and Frequency Distribution of Ectoparasites in Crossbreed Cattle in Southeastern Brazil

    PubMed Central

    Ferraz da Costa, Maria do Socorro; Guimarães, Marcos Pezzi; Lima, Walter dos Santos; Ferraz da Costa, Ana Julia; Facury Filho, Elias Jorge; Araujo, Ricardo Nascimento

    2014-01-01

    The aims of this study were to evaluate the seasonal variation and frequency distribution of Rhipicephalus (Boophilus) microplus, Haematobia irritans, and Dermatobia hominis on crossbred heifers under field conditions in the northeast of Minas Gerais state, southeastern Brazil. From November 2007 to September 2009 (23 months), 40 heifers aged 16.6 ± 2.4 months were divided into groups A (1/4 Holstein × 3/4 Gir) and B (1/2 Holstein × 1/2 Gir) and had the monthly infestation estimated along with the climatic conditions. The mean maximum and minimum temperatures were 28.5 and 19°C, respectively. The ectoparasites were present on animals in all months of the year. The levels of ticks on the animals were low (3.0 ± 0.2 ticks/animal), with the highest density in midwinter. The temperature was the climatic factor that most influenced the tick levels. The population of H. irritans (13.9 ± 0.3 flies/animal) and D. hominis (1.5 ± 0.2 larvae/animal) on heifers was more influenced by rainfall and exhibited two population peaks during the year. 1/2 Holstein heifers harbored significantly more H. irritans and D. hominis than 1/4 Holstein heifers. The results are discussed considering the most appropriate periods to apply ectoparasiticides and the genetic make-up of the animals. PMID:26464941

  7. A Tri-Band Frequency Selective Surface (FSS) to Diplex Widely Separated Bands for Millimeter Wave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Poojali, Jayaprakash; Ray, Shaumik; Pesala, Bala; Chitti, Krishnamurthy V.; Arunachalam, Kavitha

    2016-10-01

    A substrate-backed frequency selective surface (FSS) is presented for diplexing the widely separated frequency spectrum centered at 55, 89, and 183 GHz with varying bandwidth for spatial separation in the quasi-optical feed network of the millimeter wave sounder. A unit cell composed of a crossed dipole integrated with a circular ring and loaded inside a square ring is optimized for tri-band frequency response with transmission window at 89 GHz and rejection windows at 55 and 183 GHz. The reflection and transmission losses predicted for the optimized unit cell (728 μm × 728 μm) composed of dissimilar resonant shapes is less than 0.5 dB for transverse electric (TE) and transverse magnetic (TM) polarizations and wide angle of incidence (0°-45°). The FSS is fabricated on a 175-μm-thick quartz substrate using microfabrication techniques. The transmission characteristics measured with continuous wave (CW) terahertz transmit receive system are in good agreement with the numerical simulations.

  8. Time-Frequency Theta and Delta Measures Index Separable Components of Feedback Processing in a Gambling Task

    PubMed Central

    Bernat, Edward M.; Nelson, Lindsay D.; Baskin-Sommers, Arielle R.

    2014-01-01

    Previous work using gambling tasks indicate that the feedback negativity (FN) reflects primary or salient stimulus attributes (often gain vs. loss), whereas the feedback-P300 appears sensitive to secondary stimulus information. A recent time-frequency approach has characterized separable theta (3–7 Hz) and delta (0–3 Hz) feedback processes, independently sensitive to primary feedback attributes, specifically loss and gain outcomes respectively (Bernat et al., 2011). The current study extends this time-frequency work to evaluate both primary and secondary (relative outcome and outcome magnitude) feedback attributes. Consistent with previous reports, theta indexed an initial, lower-level response sensitive to the primary (most salient) feedback attributes (specifically losses), while delta was sensitive to both primary attributes (specifically gains) and assessed secondary stimulus features. PMID:25581491

  9. High-frequency variations in Earth rotation from Global Positioning System data

    NASA Astrophysics Data System (ADS)

    Rothacher, M.; Beutler, G.; Weber, R.; Hefty, J.

    2001-01-01

    Using the data of the global, dense Global Positioning System (GPS) network established by the International GPS Service a continuous, uninterrupted series of subdaily Earth rotation parameters (ERPs) with a time resolution of 2 hours has been generated at the Center for Orbit Determination in Europe. The series starts in January 1995 and has a length of more than 3 years. Starting from the 2-hour ERP values of this, to our knowledge, unique time series, the high-frequency variations in Universal Time (UT1) and polar motion (PM) due to ocean tides are studied and a set of sine and cosine coefficients is estimated for all the major tidal terms at nearly diurnal and semidiurnal frequencies. The GPS series is not very homogeneous (various processing changes during the 3 years) and still short compared to the length of very long baseline interferometry (VLBI) and satellite laser ranging (SLR) data sets. However, the results derived from this series are already of the same quality as the results from VLBI and SLR. A comparison of the tidal coefficients stemming from all three space-geodetic techniques shows an agreement on the 1 μs level for UT1 and 10 microarc seconds (μas) for PM, respectively. The RMS difference between the ocean tide amplitudes estimated from GPS data and from TOPEX/Poseidon altimeter data amounts to 0.7-0.9 μs in UT1 and 9-13 μas in PM. The residual spectrum that remains after the removal of all tidal terms has a noise level of ˜5-10 μas in PM and 0.5-1 μs in UT1 and contains nontidal signals (up to 55 μas in PM and 3 μs in UT1) that might be due to the impact of the satellite orbit modeling (12-hour revolution period of the satellites) or, alternatively, due to atmospheric or oceanic normal modes.

  10. Impact of atmospheric changes on the low-frequency variations of convective afternoon rainfall activity over Taiwan

    NASA Astrophysics Data System (ADS)

    Huang, Wan-Ru; Hsu, Huang-Hsiung; Wang, Shih-Yu; Chen, Jian-Pu

    2015-09-01

    This study examines the characteristics of low-frequency variations (defined as decadal-scale changes) in summer (June-August) convective afternoon rainfall (CAR) activity over Taiwan during 1961-2012. Using 3-hourly rain gauge data, it was found that (1) the CAR frequency exhibits a secular trend and the 10-20 decadal oscillation, (2) the trend in CAR frequency is positive in northern Taiwan but negative in central and southern Taiwan, and (3) the CAR rate increased over most of the lower plains but decreased over the mountain range of Taiwan. Diagnoses using the Japanese ReAnalysis (JRA-55) data and surface observations indicate that the low-frequency variations in CAR frequency are closely associated with the variations in monsoon southwesterly winds over the South China Sea and island-wide sea breeze convergence. The regional low-level circulation changes are linked to sea surface temperature anomalies over the Niño-4 region and its 10-20 year (quasi-decadal) oscillation. Regarding the processes that change the CAR rate in the trending patterns, it was found that increases in the moisture flux convergence and the moist (conditional) instability over the lower plains together explain the stronger CAR events in the long run.

  11. Frequency ratio of two optical clock transitions in 171Yb+ and constraints on the time variation of fundamental constants.

    PubMed

    Godun, R M; Nisbet-Jones, P B R; Jones, J M; King, S A; Johnson, L A M; Margolis, H S; Szymaniec, K; Lea, S N; Bongs, K; Gill, P

    2014-11-21

    Singly ionized ytterbium, with ultranarrow optical clock transitions at 467 and 436 nm, is a convenient system for the realization of optical atomic clocks and tests of present-day variation of fundamental constants. We present the first direct measurement of the frequency ratio of these two clock transitions, without reference to a cesium primary standard, and using the same single ion of 171Yb+. The absolute frequencies of both transitions are also presented, each with a relative standard uncertainty of 6×10(-16). Combining our results with those from other experiments, we report a threefold improvement in the constraint on the time variation of the proton-to-electron mass ratio, μ/μ=0.2(1.1)×10(-16)  yr(-1), along with an improved constraint on time variation of the fine structure constant, α/α=-0.7(2.1)×10(-17)  yr(-1). PMID:25479482

  12. Development of Equipment to Separate Nonthermal and Thermal Effects of Radio Frequency Energy on Microorganisms

    SciTech Connect

    D.J. Geveke; M. Kozempel; C. Brunkhorst

    1999-11-01

    A radio frequency (RF) dielectric heater has been developed for isolating thermal and nonthermal effects of RF energy on microorganisms in liquid foods. The modified heater enables the simultaneous application of RF energy and removal of thermal energy from the liquids. A double-pipe heat exchanger is an integral part of the heater. The outer pipe is made of Teflon. The inner pipe is made of stainless steel that is grounded in the RF circuit. Liquid food flows through the annular region between the two concentric pipes. Cooling water flows through the stainless steel pipe. The food in the annular region absorbs the RF energy. Concurrently, the cooling water flowing in the inner pipe removes the thermal energy from the food, thus controlling the temperature.

  13. A mechanism for decadal variations in the frequency of extreme El Niño events

    NASA Astrophysics Data System (ADS)

    Wang, G.; Cai, W.

    2015-12-01

    The El Niño Southern Oscillation (ENSO), the largest source of Earth's climate variability on interannual time scales, has massive impacts on extreme weathers, agriculture and ecosystems, particularly during extreme El Niño events, such as the 1982/83 and 1997/98 episodes. However, the associated mechanism is not fully understood, hindering their forecasts, as attested by the false alarm of an extreme El Niño in 2014 predicted by many models. Recent studies have identified additional precursors beyond westerly wind anomalies and oceanic heat content along the equatorial Pacific, including the southwest Pacific southerly jets, which tend to occur strongly and concurrently with equatorial westerly anomalies during extreme El Niño, but NOT during weak El Niño events. Here we show that the concurrences of southwest Pacific southerlies, anomalous equatorial westerlies, and their relationship, are modulated by the Pacific Decadal Oscillation (PDO)/Interdecadal Pacific Oscillation (IPO), even on daily timescales. During a positive phase of the PDO/IPO, occurrences of westerly wind events (WWEs), in the region between the Maritime continent and the eastern Pacific Ocean, are reinforced by the southwest Pacific southerly surges (SPSSs) in austral winter. By contrast, during a negative phase of the PDO/IPO, such SPSSs are not reinforcing WWEs; instead stronger SPSSs are associated with weaker WWEs. This interdecadal contrast in the relationship between SPSSs and WWEs contributes to the decadal variations in the frequency of extreme El Niño events. The associated mechanism will be discussed.

  14. Irreversibility and entropy production in transport phenomena, IV: Symmetry, integrated intermediate processes and separated variational principles for multi-currents

    NASA Astrophysics Data System (ADS)

    Suzuki, Masuo

    2013-10-01

    The mechanism of entropy production in transport phenomena is discussed again by emphasizing the role of symmetry of non-equilibrium states and also by reformulating Einstein’s theory of Brownian motion to derive entropy production from it. This yields conceptual reviews of the previous papers [M. Suzuki, Physica A 390 (2011) 1904; 391 (2012) 1074; 392 (2013) 314]. Separated variational principles of steady states for multi external fields {Xi} and induced currents {Ji} are proposed by extending the principle of minimum integrated entropy production found by the present author for a single external field. The basic strategy of our theory on steady states is to take in all the intermediate processes from the equilibrium state to the final possible steady states in order to study the irreversible physics even in the steady states. As an application of this principle, Gransdorff-Prigogine’s evolution criterion inequality (or stability condition) dXP≡∫dr∑iJidXi≤0 is derived in the stronger form dQi≡∫drJidXi≤0 for individual force Xi and current Ji even in nonlinear responses which depend on all the external forces {Xk} nonlinearly. This is called “separated evolution criterion”. Some explicit demonstrations of the present general theory to simple electric circuits with multi external fields are given in order to clarify the physical essence of our new theory and to realize the condition of its validity concerning the existence of the solutions of the simultaneous equations obtained by the separated variational principles. It is also instructive to compare the two results obtained by the new variational theory and by the old scheme based on the instantaneous entropy production. This seems to be suggestive even to the energy problem in the world.

  15. Separation of GRACE geoid time-variations using Independent Component Analysis

    NASA Astrophysics Data System (ADS)

    Frappart, F.; Ramillien, G.; Maisongrande, P.; Bonnet, M.

    2009-12-01

    Independent Component Analysis (ICA) is a blind separation method based on the simple assumptions of the independence of the sources and the non-Gaussianity of the observations. An approach based on this numerical method is used here to extract hydrological signals over land and oceans from the polluting striping noise due to orbit repetitiveness and present in the GRACE global mass anomalies. We took advantage of the availability of monthly Level-2 solutions from three official providers (i.e., CSR, JPL and GFZ) that can be considered as different observations of the same phenomenon. The efficiency of the methodology is first demonstrated on a synthetic case. Applied to one month of GRACE solutions, it allows to clearly separate the total water storage change from the meridional-oriented spurious gravity signals on the continents but not on the oceans. This technique gives results equivalent as the destriping method for continental water storage for the hydrological patterns with less smoothing. This methodology is then used to filter the complete series of the 2002-2009 GRACE solutions.

  16. Separation of topographic and intrinsic backscatter variations in biscopic radar images: A magic airbrush

    NASA Technical Reports Server (NTRS)

    Kirk, R. L.

    1993-01-01

    Shaded-relief maps portraying landforms as they would appear in the absence of variations in the intrinsic brightness of the surface are a venerable and extremely useful tool in planetary geology. Such maps have traditionally been produced by a highly labor intensive manual process. Skilled cartographer-artists develop detailed mental images of landforms by meticulous scrutiny of all available data, and are able to use an airbrush and electric eraser to draw these images on a map. This process becomes increasingly time-consuming or even impossible if - as is true for radar data in general and Magellan data in particular - the effects on image brightness of varying scattering properties greatly outweigh those of slope variations. Because of the difficulty of interpreting relief in the Magellan images, the airbrush technique is being used only to remove obvious artifacts from low-resolution, shaded-relief images computed digitally from altimetric data. A surprisingly simple digital-processing technique that can be applied to pairs of radar images to produce shaded-relief-like results at the full image resolution is described. These shaded-relief images can be used not only as base maps, but to improve the accuracy of quantitative topographic mapping by radarclinometry and stereoanalysis.

  17. Effects of magnitude and frequency of variations in external power output on simulated cycling time-trial performance.

    PubMed

    Wells, Marc; Atkinson, Greg; Marwood, Simon

    2013-01-01

    Mechanical models of cycling time-trial performance have indicated adverse effects of variations in external power output on overall performance times. Nevertheless, the precise influences of the magnitude and number of these variations over different distances of time trial are unclear. A hypothetical cyclist (body mass 70 kg, bicycle mass 10 kg) was studied using a mathematical model of cycling, which included the effects of acceleration. Performance times were modelled over distances of 4-40 km, mean power outputs of 200-600 W, power variation amplitudes of 5-15% and variation frequencies of 2-32 per time-trial. Effects of a "fast-start" strategy were compared with those of a constant-power strategy. Varying power improved 4-km performance at all power outputs, with the greatest improvement being 0.90 s for ± 15% power variation. For distances of 16.1, 20 and 40 km, varying power by ± 15% increased times by 3.29, 4.46 and 10.43 s respectively, suggesting that in long-duration cycling in constant environmental conditions, cyclists should strive to reduce power variation to maximise performance. The novel finding of the present study is that these effects are augmented with increasing event distance, amplitude and period of variation. These two latter factors reflect a poor adherence to a constant speed.

  18. Variation in high-frequency wave radiation from small repeating earthquakes as revealed by cross-spectral analysis

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Norishige; Uchida, Naoki; Matsuzawa, Toru; Okada, Tomomi; Nakajima, Junichi; Matsushima, Takeshi; Kono, Toshio; Hirahara, Satoshi; Nakayama, Takashi

    2016-11-01

    We examined the variation in the high-frequency wave radiation for three repeating earthquake sequences (M = 3.1-4.1) in the northeastern Japan subduction zone by waveform analyses. Earthquakes in each repeating sequence are located at almost the same place and show low-angle thrust type focal mechanisms, indicating that they represent repeated ruptures of a seismic patch on the plate boundary. We calculated cross-spectra of the waveforms and obtained the phases and coherences for pairs of events in the respective repeating sequences in order to investigate the waveform differences. We used waveform data sampled at 1 kHz that were obtained from temporary seismic observations we conducted immediately after the 2011 Tohoku earthquake near the source area. For two repeating sequences, we found that the interevent delay times for the two waveforms in a frequency band higher than the corner frequencies are different from those in a lower frequency band for particular event pairs. The phases and coherences show that there are coherent high-frequency waves for almost all the repeaters regardless of the high-frequency delays. These results indicate that high-frequency waves are always radiated from the same vicinity (subpatch) for these events but the time intervals between the ruptures of the subpatch and the centroid times can vary. We classified events in the sequence into two subgroups according to the high-frequency band interevent delays relative to the low-frequency band. For one sequence, we found that all the events that occurred just after (within 11 days) larger nearby earthquakes belong to one subgroup while other events belong to the other subgroup. This suggests that the high-frequency wave differences were caused by stress perturbations due to the nearby earthquakes. In summary, our observations suggest that high-frequency waves from the repeating sequence are radiated not from everywhere but from a long-duration subpatch within the seismic slip area. The

  19. Evidence for dietary niche separation based on infraorbital foramen size variation among subfossil lemurs.

    PubMed

    Muchlinski, Magdalena N; Godfrey, Laurie R; Muldoon, Kathleen M; Tongasoa, Lydia

    2010-01-01

    The size of the infraorbital foramen (IOF) has been used in drawing both phylogenetic and ecological inferences regarding fossil taxa. Within the order Primates, frugivores have relatively larger IOFs than folivores or insectivores. This study uses relative IOF size in lemurs to test prior trophic inferences for subfossil lemurs and to explore the pattern of variation within and across lemur families. The IOFs of individuals belonging to 12 extinct lemur species were measured and compared to those of extant Malagasy strepsirhines. Observations matched expectations drawn from more traditional approaches (e.g. dental morphology and microwear, stable isotope analysis) remarkably well. We confirm that extinct lemurs belonging to the families Megaladapidae and Palaeopropithecidae were predominantly folivorous and that species belonging to the genus Pachylemur (Lemuridae) were frugivores. Very high values for relative IOF area in Archaeolemur support frugivory but are also consistent with omnivory, as certain omnivores use facial touch cues while feeding. These results provide additional evidence that the IOF can be used as an informative osteological feature in both phylogenetic and paleoecological interpretations of the fossil record.

  20. Temporal variations of cathode performance in air-cathode single-chamber microbial fuel cells with different separators

    NASA Astrophysics Data System (ADS)

    Ma, Jinxing; Wang, Zhiwei; Suor, Denis; Liu, Shumeng; Li, Jiaqi; Wu, Zhichao

    2014-12-01

    An ideal separator is essential for efficient power production from air-cathode single-chamber microbial fuel cells (MFCs). In this study, we use different kinds of membranes as separators, including Nafion 117 proton exchange membrane, polyethersulfone and poly(vinylidene fluoride) microfiltration membranes. Temporal variations of cathode performance are monitored during the experiment. Results show that MFCs with microfiltration membranes present higher power output but deterioration is still observed after about 600-h operation. With the utilization of appropriate separators (e.g., polyethersulfone membrane), biofouling, cation fouling and chemical scale fouling of the cathodes are alleviated while reaction fouling seems inevitable. Moreover, it is found that Coulombic efficiency (CE) and energy efficiency (EE) are also related to the cathode performance. Despite relatively high oxygen diffusivity (1.49 × 10-5 cm2 s-1), CE and EE of the MFC with 0.1 μm pore-size polyethersulfone membrane can reach 92.8% and 13.7%, respectively, when its average power density registers 403.5 mW m-2. This phenomenon might be attributed to the finding that the overall substrate consumption rate due to oxygen reduction and respiration is almost constant in the air-cathode MFCs. Oxygen leakage into the electrolyte can be inhibited due to the efficient oxygen reduction reaction on the surface of the cathode.

  1. Annual ionospheric variations of the critical frequency foF2 at the equatorial stations during the solar minima

    NASA Astrophysics Data System (ADS)

    Biktash, Lilia

    2016-07-01

    We have analyzed annual ionospheric variations of the critical frequency foF2 at the equatorial stations during the solar minima. There are essential distinctions between the global TEC (total electron content) and foF2 annual variations during the last two solar minima. Many authors concluded that the annual means of foF2 and the global TEC were reduced, while others investigations no found essential variations as compared with the previous solar minimum. Most if not all of authors suppose that the possible source of this phenomenon is the low level of the EUV (extreme ultraviolet) during the solar minima. The aim of our paper is to amplify these conclusions or to propose new factor which can change ionosphere parameters during the solar minima. We calculated annual variations of foF2 at the equatorial stations and compared these data with Dst annual variations. We found that in addition to low level of the EUV during the solar minima, geomagnetic storms effects have to be included as the influencing factor on annual ionospheric variations.

  2. High frequency genetic variation of purine biosynthesis genes is a mechanism of success in Campylobacter jejuni

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phenotypic variation is prevalent among progeny of the zoonotic pathogen Campylobacter jejuni, the leading agent of enterocolitis in the developed world. Heterogeneity bestows increased survival to bacterial populations because variable phenotypes ensure some cells will be protected against future s...

  3. Parameterizing both path amplitude and delay variations of underwater acoustic channels for block decoding of orthogonal frequency division multiplexing.

    PubMed

    Xu, Xiaoka; Wang, Zhaohui; Zhou, Shengli; Wan, Lei

    2012-06-01

    There are no commonly-agreed mathematical models for the input-output relationship of underwater acoustic channels. For each path in a time-varying multipath channel within a short period of time (e.g., one short data block), this paper proposes to use one polynomial to approximate the amplitude variation and another polynomial up to the first order to approximate the delay variation within a block duration. Under such a channel parameterization, the discrete-time channel input- output relationship tailored to zero-padded orthogonal-frequency-division-multiplexing (OFDM) transmissions is then derived, based on which an OFDM receiver is validated using experimental data collected during the 2008 Surface Processes and Acoustic Communications Experiment. For channels with a short coherence time, the numerical results show that incorporating both the amplitude and delay variations improves the system performance.

  4. Implementing fast sideband-modulated ``wah-wah'' pulses for driving transmon qubits with tight frequency separation

    NASA Astrophysics Data System (ADS)

    Vesterinen, V.; Saira, O.-P.; Bruno, A.; Egger, D. J.; Wilhelm, F. K.; Dicarlo, L.

    2014-03-01

    Packing multiple transmon qubits in a narrow frequency band is challenging due to the limited transmon anharmonicity: control drives targeting one qubit may drive the leakage transition of another. This cross-driving effect grows with decreasing gate time, potentially imposing a quantum speed limit. The widely used DRAG (derivative removal by adiabatic gate) technique only suppresses leakage in the targeted transmon. Adding a modulation tone to a Gaussian pulse envelope in one quadrature, and complementing with DRAG in the other, has been predicted [1] to reduce both intrinsic and cross-driving leakage. We have experimentally verified the performance of this new pulse-shaping method, termed ``wah-wah,'' with two transmons in a 2D circuit QED architecture. We optimize the modulation frequency and amplitude, and characterize the gate fidelity using randomized benchmarking (RB) and quantum process tomography. Pulses on the two qubits are characterized separately and simultaneously by interleaving the RB sequences. Wah-wah pulses show decoherence-limited fidelity at gate speeds where DRAG pulses add significant error. Research supported by NWO, EU projects SOLID and SCALEQIT, and the Research Foundation of Helsinki University of Technology.

  5. Variation in the Frequency and Extent of Hybridization between Leucosceptrum japonicum and L. stellipilum (Lamiaceae) in the Central Japanese Mainland

    PubMed Central

    Li, Yue; Maki, Masayuki

    2015-01-01

    Variations in the frequency and extent of hybridization among mixed populations located in the same contact zone provide natural laboratories for the study of extrinsic reproductive isolation maintaining species integrity. In this study, we examined the pattern of hybridization between L. japonicum and L. stellipilum among mixed populations in different localities of a contact zone. The genetic structures from three sympatric populations and six mixed populations in the hybrid zone, and five reference populations far from the contact zone, were characterized using 10 neutral nuclear microsatellite markers. Evidence from genetic distance-based clustering analysis, the frequency distribution of admixture proportion values, and the hybrid category assignment approaches indicated that the frequency and extent of hybridization varied considerably among populations in the contact zone between L. japonicum and L. stellipilum. One likely explanation is that variation in exogenous (ecological) selection among populations might contribute to differences in frequency and extent of hybridization. The present study will facilitate future research exploring the evolution of reproductive isolation between L. japonicum and L. stellipilum. PMID:25738505

  6. Variation in the frequency and extent of hybridization between Leucosceptrum japonicum and L. stellipilum (Lamiaceae) in the Central Japanese Mainland.

    PubMed

    Li, Yue; Maki, Masayuki

    2015-01-01

    Variations in the frequency and extent of hybridization among mixed populations located in the same contact zone provide natural laboratories for the study of extrinsic reproductive isolation maintaining species integrity. In this study, we examined the pattern of hybridization between L. japonicum and L. stellipilum among mixed populations in different localities of a contact zone. The genetic structures from three sympatric populations and six mixed populations in the hybrid zone, and five reference populations far from the contact zone, were characterized using 10 neutral nuclear microsatellite markers. Evidence from genetic distance-based clustering analysis, the frequency distribution of admixture proportion values, and the hybrid category assignment approaches indicated that the frequency and extent of hybridization varied considerably among populations in the contact zone between L. japonicum and L. stellipilum. One likely explanation is that variation in exogenous (ecological) selection among populations might contribute to differences in frequency and extent of hybridization. The present study will facilitate future research exploring the evolution of reproductive isolation between L. japonicum and L. stellipilum. PMID:25738505

  7. Time-Frequency Analysis of Beach Bacteria Variations and its Implication for Recreational Water Quality Modeling

    EPA Science Inventory

    This paper explores the potential of time-frequency wavelet analysis in resolving beach bacteria concentration and possible explanatory variables across multiple time scales with temporal information still preserved. The wavelet scalograms of E. coli concentrations and the explan...

  8. Two-Point Observations of High- and Low-Frequency Variations of Helium Abundance in the Solar Win

    NASA Astrophysics Data System (ADS)

    Safrankova, J.; Cagas, P.; Nemecek, Z.; Prech, L.; Zastenker, G. N.; Riazantseva, M.

    2014-12-01

    Variations of the abundance of heavy species observed in the solar wind are usually attributed to spacecraft encounters with streams emanating from different places and altitudes in the source region and their further evolution is considered as being negligible. These conclusions are based on an analysis of highly averaged data and much less attention was devoted to variations on the time scale of seconds. The BMSW instrument onboard the Spektr-R spacecraft provides a high-time resolution data of the helium and proton fluxes and proton velocity, density, and temperature that suitable for investigations of rapid variations. The paper compares measurements in two points (Spektr-R and Wind) and focuses on the changes of helium abundance on this middle scale and on their correlations with variations of other parameters. We have found that only a low-frequency part of He abundance variations can be attributed to changes of the source region, whereas a significant portion of them could be generated by in-transit turbulence that is probably driven by the speed difference between the ion species.

  9. Searches for high frequency variations in the 8-B neutrino flux at the Sudbury neutrino observatory

    SciTech Connect

    Rielage, Keith; Seibert, Stanley R; Hime, Andrew; Elliott, Steven R; Stonehill, L C; Wouters, J M; Aharmim, B; Ahmed, S N; Anthony, A E; Barros, N; Beier, E W; Bellerive, A; Belttran, B; Bergevin, M; Biller, S D; Boudjemline, K; Burritt, T H; Cai, B; Chan, Y D; Chauhan, D; Chen, M; Cleveland, B T; Cox - Mobrand, G A; Dai, X; Deng, H; Detwiler, J; Dimarco, M; Doe, P J; Drouin, P - L; Duba, C A; Duncan, F A; Dunford, M; Earle, E D; Evans, H C; Ewan, G T; Farine, J; Fergani, H; Fleurot, F; Ford, R J; Formaggilo, J A; Gagnon, N; Goon, J Tm; Guillian, E; Habib, S; Hahn, R L; Hallin, A L; Hallman, E D; Harvey, P J; Hazama, R; Heintzelman, W J; Heise, J; Helmer, R L; Howard, C; Howe, M A; Huang, M; Jamieson, B; Jelley, N A; Keeter, K J; Klein, J R; Kos, M; Kraus, C; Krauss, C B; Kutter, T; Kyba, C C M; Law, J; Lawson, I T; Lesko, K T; Leslie, J R; Loach, J C; Maclellan, R; Majerus, S; Mak, H B; Maneira, J; Martin, R; Mccauley, N; Mc Donald, A B; Mcgee, S; Miffin, C; Miller, M L; Monreal, B; Monroe, J; Morissette, B; Nickel, B G; Noble, A J; O' Keeffe, H M; Oblath, N S; Orebi Gann, G D; Oser, S M; Ott, R A; Peeters, S J M; Poon, A W P; Prior, G; Reitzner, S D; Robertson, B C; Robertson, R G H; Rollin, E; Schwendener, M H; Secrest, J A; Seibert, S R; Simard, O; Sinclair, D; Sinclair, L; Skensved, P; Sonley, T J; Tesic, G; Tolich, N; Tsui, T; Tunnell, C D; Van Berg, R; Van Devender, B A; Virtue, C J; Wall, B L; Waller, D; Wan Chan Tseung, H; West, N; Wilkerson, J F; Wilson, J R; Wright, A; Yeh, M; Zhang, F; Zuber, K

    2009-01-01

    We have peformed three searches for high-frequency signals in the solar neutrino flux measured by the Sudbury Neutrino Observatory (SNO), motivated by the possibility that solar g-mode oscillations could affect the production or propagation of solar {sup 8}B neutrinos. The first search looked for any significant peak in the frequency range l/day to 144/day, with a sensitivity to sinusoidal signals with amplitudes of 12% or greater. The second search focused on regions in which g-mode signals have been claimed by experiments aboard the SoHO satellite, and was sensitive to signals with amplitudes of 10% or greater. The third search looked for extra power across the entire frequency band. No statistically significant signal was detected in any of the three searches.

  10. Variation of Magnetic Particle Imaging Tracer Performance With Amplitude and Frequency of the Applied Magnetic Field

    PubMed Central

    Khandhar, Amit P.; Kemp, Scott J.; Ota, Satoshi; Nakamura, Kosuke; Takemura, Yasushi; Krishnan, Kannan M.

    2015-01-01

    The magnetic response of magnetic particle imaging (MPI) tracers varies with the slew rate of the applied magnetic field, as well as with the tracer's average magnetic core size. Currently, 25 kHz and 20 mT/μ0 drive fields are common in MPI, but lower field amplitudes may be necessary for patient safety in future designs. We studied how several different sizes of monodisperse MPI tracers behaved under different drive field amplitude and frequency, using magnetic particle spectrometry and ac hysteresis for drive field conditions at 16, 26, and 40 kHz, with field amplitudes from 5 to 40 mT/μ0. We observed that both field amplitude and frequency can influence the tracer behavior, but that the magnetic behavior is consistent when the slew rate (the product of field amplitude and frequency) is consistent. However, smaller amplitudes provide a correspondingly smaller field of view, sometimes resulting in excitation of a minor hysteresis loop. PMID:26023242

  11. Space Shuttle Redesigned Solid Rocket Motor nozzle natural frequency variations with burn time

    NASA Technical Reports Server (NTRS)

    Lui, C. Y.; Mason, D. R.

    1991-01-01

    The effects of erosion and thermal degradation on the Space Shuttle Redesigned Solid Rocket Motor (RSRM) nozzle's structural dynamic characteristics were analytically evaluated. Also considered was stiffening of the structure due to internal pressurization. A detailed NASTRAN finite element model of the nozzle was developed and used to evaluate the influence of these effects at several discrete times during motor burn. Methods were developed for treating erosion and thermal degradation, and a procedure was developed to account for internal pressure stiffening using differential stiffness matrix techniques. Results were verified using static firing test accelerometer data. Fast Fourier Transform and Maximum Entropy Method techniques were applied to the data to generate waterfall plots which track modal frequencies with burn time. Results indicate that the lower frequency nozzle 'vectoring' modes are only slightly affected by erosion, thermal effects and internal pressurization. The higher frequency shell modes of the nozzle are, however, significantly reduced.

  12. Longitudinal frequency variation of long-lasting EMIC Pc1-Pc2 waves localized in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Kim, K.-H.; Shiokawa, K.; Mann, I. R.; Park, J.-S.; Kwon, H.-J.; Hyun, K.; Jin, H.; Connors, M.

    2016-02-01

    Long-lasting (> 20 h) electromagnetic ion cyclotron (EMIC) Pc1-Pc2 waves were observed by the Athabasca (L =˜ 4.6) induction magnetometer and Canadian Array for Realtime Investigations of Magnetic Activity (L =˜ 4-6) fluxgate magnetometers on 5 April 2007. These waves showed a systematic frequency change with local time, the minimum frequency near dusk, and the maximum frequency near dawn. Assuming the plasmapause as a potential source region of the waves, we estimated the plasmapause location from localized proton enhancement (LPE) events observed at NOAA-Polar Orbiting Environmental Satellites and METOP-2 satellites. We found that the longitudinal frequency variation of EMIC waves has a clear correlation with the estimated plasmapause location and that the waves are in the frequency band between the equatorial helium and oxygen gyrofrequencies at the estimated plasmapause. With our analysis results we suggest that the LPE events are caused by wave-particle interaction with the helium band EMIC waves generated near the plasmapause.

  13. Vowel Identification by Listeners with Hearing Impairment in Response to Variation in Formant Frequencies

    ERIC Educational Resources Information Center

    Molis, Michelle R.; Leek, Marjorie R.

    2011-01-01

    Purpose: This study examined the influence of presentation level and mild-to-moderate hearing loss on the identification of a set of vowel tokens systematically varying in the frequency locations of their second and third formants. Method: Five listeners with normal hearing (NH listeners) and five listeners with hearing impairment (HI listeners)…

  14. Active noise control using noise source having adaptive resonant frequency tuning through stress variation

    NASA Technical Reports Server (NTRS)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor); Renshaw, Anthony A. (Inventor); Hedeen, Robert A. (Inventor)

    1995-01-01

    A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by an expandable ring embedded in the noise radiating element. Excitation of the ring causes expansion or contraction of the ring, thereby varying the stress in the noise radiating element. The ring is actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the ring, causing the ring to expand or contract. Instead of a single ring embedded in the noise radiating panel, a first expandable ring can be bonded to one side of the noise radiating element, and a second expandable ring can be bonded to the other side.

  15. Path loss variation of on-body UWB channel in the frequency bands of IEEE 802.15.6 standard.

    PubMed

    Goswami, Dayananda; Sarma, Kanak C; Mahanta, Anil

    2016-06-01

    The wireless body area network (WBAN) has gaining tremendous attention among researchers and academicians for its envisioned applications in healthcare service. Ultra wideband (UWB) radio technology is considered as excellent air interface for communication among body area network devices. Characterisation and modelling of channel parameters are utmost prerequisite for the development of reliable communication system. The path loss of on-body UWB channel for each frequency band defined in IEEE 802.15.6 standard is experimentally determined. The parameters of path loss model are statistically determined by analysing measurement data. Both the line-of-sight and non-line-of-sight channel conditions are considered in the measurement. Variations of parameter values with the size of human body are analysed along with the variation of parameter values with the surrounding environments. It is observed that the parameters of the path loss model vary with the frequency band as well as with the body size and surrounding environment. The derived parameter values are specific to the particular frequency bands of IEEE 802.15.6 standard, which will be useful for the development of efficient UWB WBAN system.

  16. Path loss variation of on-body UWB channel in the frequency bands of IEEE 802.15.6 standard.

    PubMed

    Goswami, Dayananda; Sarma, Kanak C; Mahanta, Anil

    2016-06-01

    The wireless body area network (WBAN) has gaining tremendous attention among researchers and academicians for its envisioned applications in healthcare service. Ultra wideband (UWB) radio technology is considered as excellent air interface for communication among body area network devices. Characterisation and modelling of channel parameters are utmost prerequisite for the development of reliable communication system. The path loss of on-body UWB channel for each frequency band defined in IEEE 802.15.6 standard is experimentally determined. The parameters of path loss model are statistically determined by analysing measurement data. Both the line-of-sight and non-line-of-sight channel conditions are considered in the measurement. Variations of parameter values with the size of human body are analysed along with the variation of parameter values with the surrounding environments. It is observed that the parameters of the path loss model vary with the frequency band as well as with the body size and surrounding environment. The derived parameter values are specific to the particular frequency bands of IEEE 802.15.6 standard, which will be useful for the development of efficient UWB WBAN system. PMID:27382482

  17. Corner Frequency Variation in the Southeastern Region of the 1992 Nicaragua Tsunami Earthquake

    NASA Astrophysics Data System (ADS)

    Rotman, H. M. M.; Bilek, S. L.; Phillips, W. S.

    2014-12-01

    At the Nicaragua portion of the Middle America Trench, where the Cocos Plate is subducting at ~85 mm/yr, a tsunami earthquake (mb 5.3, Ms 7.2, Mw 7.6) occurred at 15 km depth on 2 September 1992, causing a tsunami up to 8 m high and >116 deaths. A tsunami earthquake is characterized by deficiency in high frequency radiated energy and large tsunami for its Ms. Tsunami earthquakes are relatively rare, but their occurrence presents a significant hazard to coastal populations, so the potential to identify tsunami earthquake regions has wide-reaching hazard implications. Here we examine the notion that the cause of the dominantly low frequency energy in the 1992 tsunami earthquake may also manifest in small earthquakes in the same area. We examine 241 events within and south of the 1992 rupture limits with hypocenters 8-30 km depth and 1.7 < Mw < 4.6, recorded by land station and ocean bottom seismometers in southern Nicaragua and northern Costa Rica from November 2005 to June 2006. Event source parameters moment, corner frequency, and stress drop are determined using the spectral ratios of S-wave coda. Mean stress drop inside the 1992 rupture area is 3.2 MPa, and immediately south of the 1992 rupture zone mean stress drop is 10.4 MPa. Inside and outside the 1992 rupture zone at similar depths, the increase in stress drop is by a factor of five and occurs abruptly over <50 km. The mean corner frequency of events in the 1992 rupture area is ~45% the mean corner frequency value for events south of the 1992 rupture zone. Therefore, our results demonstrate different source parameter characteristics for microseismicity in the region of a past tsunami earthquake. If this finding can be reproduced at other subduction zones, it may significantly improve subduction zone coastal hazard assessment.

  18. Seasonal and regional variations in extreme precipitation event frequency using CMIP5

    NASA Astrophysics Data System (ADS)

    Janssen, E.; Sriver, R. L.; Wuebbles, D. J.; Kunkel, K. E.

    2016-05-01

    Understanding how the frequency and intensity of extreme precipitation events are changing is important for regional risk assessments and adaptation planning. Here we use observational data and an ensemble of climate change model experiments (from the Coupled Model Intercomparison Project Phase 5 (CMIP5)) to examine past and potential future seasonal changes in extreme precipitation event frequency over the United States. Using the extreme precipitation index as a metric for extreme precipitation change, we find key differences between models and observations. In particular, the CMIP5 models tend to overestimate the number of spring events and underestimate the number of summer events. This seasonal shift in the models is amplified in projections. These results provide a basis for evaluating climate model skill in simulating observed seasonality and changes in regional extreme precipitation. Additionally, we highlight key sources of variability and uncertainty that can potentially inform regional impact analyses and adaptation planning.

  19. Monitoring of ULF (ultra-low-frequency) Geomagnetic Variations Associated with Earthquakes

    PubMed Central

    Hayakawa, Masashi; Hattori, Katsumi; Ohta, Kenji

    2007-01-01

    ULF (ultra-low-frequency) electromagnetic emission is recently recognized as one of the most promising candidates for short-term earthquake prediction. This paper reviews previous convincing evidence on the presence of ULF emissions before a few large earthquakes. Then, we present our network of ULF monitoring in the Tokyo area by describing our ULF magnetic sensors and we finally present a few, latest results on seismogenic electromagnetic emissions for recent large earthquakes with the use of sophisticated signal processings.

  20. High-frequency variations in Earth rotation and the planetary momentum budget

    NASA Technical Reports Server (NTRS)

    Rosen, Richard D.

    1995-01-01

    The major focus of the subject contract was on helping to resolve one of the more notable discrepancies still existing in the axial momentum budget of the solid Earth-atmosphere system, namely the disappearance of coherence between length-of-day (l.o.d.) and atmospheric angular momentum (AAM) at periods shorter than about a fortnight. Recognizing the importance of identifying the source of the high-frequency momentum budget anomaly, the scientific community organized two special measurement campaigns (SEARCH '92 and CONT '94) to obtain the best possible determinations of l.o.d. and AAM. An additional goal was to analyze newly developed estimates of the torques that transfer momentum between the atmosphere and its underlying surface to determine whether the ocean might be a reservoir of momentum on short time scales. Discrepancies between AAM and l.o.d. at sub-fortnightly periods have been attributed to either measurement errors in these quantities or the need to incorporate oceanic angular momentum into the planetary budget. Results from the SEARCH '92 and CONT '94 campaigns suggest that when special attention is paid to the quality of the measurements, better agreement between l.o.d. and AAM at high frequencies can be obtained. The mechanism most responsible for the high-frequency changes observed in AAM during these campaigns involves a direct coupling to the solid Earth, i.e, the mountain torque, thereby obviating a significant oceanic role.

  1. Process Inference from High Frequency Temporal Variations in Dissolved Organic Carbon (DOC) Dynamics Across Nested Spatial Scales

    NASA Astrophysics Data System (ADS)

    Tunaley, C.; Tetzlaff, D.; Lessels, J. S.; Soulsby, C.

    2014-12-01

    In order to understand aquatic ecosystem functioning it is critical to understand the processes that control the spatial and temporal variations in DOC. DOC concentrations are highly dynamic, however, our understanding at short, high frequency timescales is still limited. Optical sensors which act as a proxy for DOC provide the opportunity to investigate near-continuous DOC variations in order to understand the hydrological and biogeochemical processes that control concentrations at short temporal scales. Here we present inferred 15 minute stream water DOC data for a 12 month period at three nested scales (1km2, 3km2 and 31km2) for the Bruntland Burn, a headwater catchment in NE Scotland. High frequency data were measured using FDOM and CDOM probes which work by measuring the fluorescent component and coloured component, respectively, of DOC when exposed to ultraviolet light. Both FDOM and CDOM were strongly correlated (r2 >0.8) with DOC allowing high frequency estimations. Results show the close coupling of DOC with discharge throughout the sampling period at all three spatial scales. However, analysis at the event scale highlights anticlockwise hysteresis relationships between DOC and discharge due to the delay in DOC being flushed from the increasingly large areas of peaty soils as saturation zones expand and increase hydrological connectivity. Lag times vary between events dependent on antecedent conditions. During a 10 year drought period in late summer 2013 it was apparent that very small changes in discharge on a 15 minute timescale result in high increases in DOC. This suggests transport limitation during this period where DOC builds up in the soil and is not flushed regularly, therefore any subsequent increase in discharge results in large DOC peaks. The high frequency sensors also reveal diurnal variability during summer months related to the photo-oxidation, evaporative and biological influences of DOC during the day. This relationship is less

  2. Greater variation in BCL-2 mutation frequency among lymphocytes of heavy smokers than among those of controls

    SciTech Connect

    Cortopassi, G.A.; Liu, Y.; Bell, D.A.

    1994-12-31

    It is possible that the risk for tumors in specific human individuals might be most usefully estimated by determining the frequency of (rare) somatic mutations at oncogenic loci in their tissue. Using a sensitive nested PCR assay, we have investigated the frequency of rare t(14;18) (q32;q21) translocations at the bcl-2 proto-oncogene locus in peripheral blood lymphocytes of 85 smokers and 36 control non-smokers. The variation in translocation frequencies (plus or minus the variation at the 95% confidence interval) were 1.4 {+-} -0.37 per million lymphocytes among smokers, versus 0.53 {+-} -0.20 among non-smokers, a 2.6-fold excess of such oncogenic translocations among lymphocytes of smokers. Logistic regression analysis including age, race, sex, years of smoking and pack-years indicated that only current smoking was significantly associated with increased frequency of the translocation of bcl-2 occur in 85% of follicular lymphoma tumors, and about 50% of all Non-Hodgkin`s Lymphoma, and are thought to be the result of errors of the V(D)J recombinase. Epidemiological studies by others have shown that there is about a two-fold higher relative risk of Non-Hodgkin`s Lymphoma for heavy smokers vs. non-smokers. We speculate that one reason for excess NHL tumors among heavy smokers may be their increased average burden of t(14;18) mutations, and that smoke-derived substances may induce errors of the V(D)J recombinase by mutagenic or antigenic mechanisms.

  3. Improving Processes of Mechanized Pulsed Arc Welding of Low-Frequency Range Variation of Mode Parameters

    NASA Astrophysics Data System (ADS)

    Saraev, Yu N.; Solodskiy, S. A.; Ulyanova, O. V.

    2016-04-01

    A new technology of low-frequency modulation of the arc current in MAG and MIG welding is presented. The technology provides control of thermal and crystallization processes, stabilizes the time of formation and crystallization of the weld pool. Conducting theoretical studies allowed formulating the basic criteria for obtaining strong permanent joints for high-duty structures, providing conditions for more equilibrium structure of the deposited metal and the smaller width of the HAZ. The stabilization of time of the formation and crystallization of the weld pool improves the formation of the weld and increases productivity in welding thin sheet metal.

  4. Variation in low-frequency estimates of sound levels based on different units of analysis.

    PubMed

    Hawkins, Russell S; Miksis-Olds, Jennifer L; Smith, Chad M

    2014-02-01

    The measurement and analysis of underwater sound is a complicated process because of the variable durations of contributing sources and constantly changing water column dynamics. Because the ambient sound distribution does not always follow a Gaussian structure and may be nonstationary in time, analysis over an extended period is required to accurately characterize the data. Utilizing recordings from the Indian Ocean, the temporal variation in ambient sound including transient signals was examined using multiple processing window lengths and subsampling intervals. Results illustrate the degree of uncertainty in sound levels based on different units of analysis. The average difference between sound level estimates in the 10-30 Hz band due to subsampling was 2 dB and as high as 4 dB. The difference in the full band (5-110 Hz) was as high as 6 dB. Longer averaging windows (200 vs 60 s) resulted in larger variations over different subsampling intervals. This work demonstrates how sampling protocols within a single dataset can influence results and acknowledges that comparative studies at the same location but with different sampling protocols can be substantial if signal processing parameters are not statistically accounted for to confirm interpretation of results and observed trends.

  5. Low-frequency normal modes that describe allosteric transitions in biological nanomachines are robust to sequence variations.

    PubMed

    Zheng, Wenjun; Brooks, Bernard R; Thirumalai, D

    2006-05-16

    By representing the high-resolution crystal structures of a number of enzymes using the elastic network model, it has been shown that only a few low-frequency normal modes are needed to describe the large-scale domain movements that are triggered by ligand binding. Here we explore a link between the nearly invariant nature of the modes that describe functional dynamics at the mesoscopic level and the large evolutionary sequence variations at the residue level. By using a structural perturbation method (SPM), which probes the residue-specific response to perturbations (or mutations), we identify a sparse network of strongly conserved residues that transmit allosteric signals in three structurally unrelated biological nanomachines, namely, DNA polymerase, myosin motor, and the Escherichia coli chaperonin. Based on the response of every mode to perturbations, which are generated by interchanging specific sequence pairs in a multiple sequence alignment, we show that the functionally relevant low-frequency modes are most robust to sequence variations. Our work shows that robustness of dynamical modes at the mesoscopic level is encoded in the structure through a sparse network of residues that transmit allosteric signals.

  6. Low-frequency variations in sea level and currents in south San Francisco Bay

    SciTech Connect

    Walters, R.A.

    1982-07-01

    In order to examine physical processes in the subtidal time range, sea-level and current meter data for south San Francisco Bay (South Bay) were filtered using a low-pass digital filter to remove tidal period variations, and then subjected to an empirical orthogonal function analysis. For the the sea-level data, there is one dominant empirical mode that is correlated with nonlocal coastal forcing. A small amount of the variance is associated with local wind setup. For the current meter data, there are two dominant empirical modes that correlate with local wind forcing and tidal forcing over the spring-neap cycle. In general, South Bay is dominated by coastal forcing on sea level during all seasons, and dominated by wind and tidal forcing on the residual currents during the summer.

  7. Low-frequency variations in sea level and currents in south San Francisco Bay

    USGS Publications Warehouse

    Walters, Roy A.

    1982-01-01

    In order to examine physical process in the subtidal time range, sea-level and current meter data for south San Francisco Bay (South Bay) were filtered using a low-pass digital filter to remove tidal period variations. and then subjected to an empirical orthogonal function analysis. For the sea-level data, there is one dominant empirical mode that is correlated with nonlocal coastal forcing. A small amount of the variance is associated with local wind setup. For the current meter data, there are two dominant empirical modes that correlate with local wind forcing and tidal forcing over the spring-neap cycle. In general, South Bay is dominated by coastal forcing on sea level during all seasons, and dominated by wind and tidal forcing on the residual currants during the summer.

  8. Forcing of polar motion in the Chandler frequency band: An opportunity to evaluate interannual climate variations

    NASA Astrophysics Data System (ADS)

    Plag, H.-P.; Chao, B. F.; Gross, R. S.; Van Dam, T.

    The Earth rotates about its axis once per day but does not do so uniformly. The length of the day changes by as much as a millisecond from day to day and the Earth wobbles as it rotates. That the Earth should wobble was predicted by the Swiss mathematician Leonhard Euler in 1765, but it was not until 1891 that the wobbling motion of the Earth was detected by the American astronomer Seth Carlo Chandler, Jr. In fact, Chandler observed that the Earth has two distinct wobbles, one with an annual period and the other with a 14-month period. The annual wobble is a forced motion of the Earth caused by seasonal variations in the atmosphere, oceans, and hydrosphere.

  9. Frequency of close companions among Kepler planets—a transit time variation study

    SciTech Connect

    Xie, Ji-Wei; Wu, Yanqin; Lithwick, Yoram E-mail: wu@astro.utoronto.ca

    2014-07-10

    A transiting planet exhibits sinusoidal transit time variations (TTVs) if perturbed by a companion near a mean-motion resonance. We search for sinusoidal TTVs in more than 2600 Kepler candidates, using the publicly available Kepler light curves (Q0-Q12). We find that the TTV fractions rise strikingly with the transit multiplicity. Systems where four or more planets transit enjoy a TTV fraction that is roughly five times higher than those where a single planet transits, and about twice as high as those for doubles and triples. In contrast, models in which all transiting planets arise from similar dynamical configurations predict comparable TTV fractions among these different systems. One simple explanation for our results is that there are at least two different classes of Kepler systems, one closely packed and one more sparsely populated.

  10. Can the Tibetan Plateau snow cover influence the interannual variations of Eurasian heat wave frequency?

    NASA Astrophysics Data System (ADS)

    Wu, Zhiwei; Zhang, Peng; Chen, Hua; Li, Yun

    2016-06-01

    The Eurasian continent has experienced significant year-to-year variations of summer heat waves during the past decades. Several possible factors, such as ocean temperature, soil moisture, and changes in land use and greenhouse gases, have been identified in previous studies, but the mechanisms are still unclear. In this study, it is found that the Tibetan Plateau snow cover (TPSC) is closely linked to the interannual variations of summer heat waves over Eurasia. The TPSC variability explains more than 30 % of the total variances of heat wave variability in the southern Europe and northeastern Asia (SENA) region. A set of numerical experiments reveal that the reduced TPSC may induce a distinct teleconnection pattern across the Eurasian continent, with two anomalous high pressure centers in the upper troposphere over the SENA region, which may lead to a reduction of the cloud formation near the surface. The less cloud cover tends to increase the net shortwave radiation and favor a stronger surface sensible heat flux in the dry surface condition over the SENA region, resulting in a deeper, warmer and drier atmospheric boundary layer that would further inhibit the local cloud formation. Such a positive land-atmosphere feedback may dry the surface even further, heat the near-surface atmosphere and thereby intensify the local heat waves. The above dynamical processes also operate on interdecadal time scales. Given the reduction of the TPSC could become more pronounced with increasing levels of greenhouse gases in a warming climate, we infer that the TPSC may play an increasingly important role in shaping the summer heat waves over the SENA region in next decades.

  11. Solar radial velocity variations and the search for Venus enabled by a laser frequency comb

    NASA Astrophysics Data System (ADS)

    Phillips, David F.; Dumusque, Xavier; Li, Chih-Hao; Glenday, Alexander; Sasselov, Dimitar; Szentgyorgyi, Andrew; Walsworth, Ronald L.

    2016-05-01

    We have recently demonstrated 50 cm/s sensitivity in measuring the radial velocity (RV) between the Earth and Sun using a simple, compact solar telescope feeding the HARPS-N spectrograph at the Italian National Telescope calibrated with our green astro-comb. The green astro-comb is a laser frequency comb optimized for calibrating astrophysical spectrographs. We have been operating the solar telescope to detect the RV signal of the Sun as a star for the past year both to study RV jitter associated with stellar (solar) fluctuations and to demonstrate sensitivity of these instruments to detect terrestrial exoplanets. In this talk I will present results from calibrating the HARPS-N exoplanet searcher spectrograph, solar RV stability, and the current status of our search for the signature of Venus.

  12. A surface epitope undergoing high-frequency phase variation is shared by Mycoplasma gallisepticum and Mycoplasma bovis.

    PubMed Central

    Yogev, D; Menaker, D; Strutzberg, K; Levisohn, S; Kirchhoff, H; Hinz, K H; Rosengarten, R

    1994-01-01

    We have recently reported that three distinct size- and phase-variable surface lipoproteins (Vsps) of the bovine pathogen Mycoplasma bovis possess a common epitope recognized by monoclonal antibody 1E5. In the present study, we show that this epitope is also present on a size-variant protein (PvpA) of the avian pathogen Mycoplasma gallisepticum. Application of monoclonal antibody 1E5 in Western immunoblot analysis of Triton X-114 phase-fractionated proteins and in colony immunoblots, as well as in trypsin and carboxypeptidase digestion experiments, has demonstrated that (i) PvpA is an integral membrane protein with a free C terminus, (ii) the shared epitope is surface exposed, and (iii) PvpA is subjected to high-frequency phase variation in expression. By using serum antibodies from M. gallisepticum-infected chickens, we were able to demonstrate the immunogenic nature of PvpA and identify three additional highly immunogenic Triton X-114 phase proteins (p67, p72, and p75) also undergoing high-frequency phase variation spontaneously and independently. Metabolic labeling experiments with [14C]palmitate and [14C]oleate revealed that PvpA, in contrast to p67, p72, and p75, is not lipid modified. Southern blot hybridization with restriction fragments carrying the pvpA gene of M. gallisepticum or the vspA gene of M. bovis against digested genomic DNA of the two Mycoplasma species indicated the absence of genetic relatedness between the pvpA and vspA genes. The apparent complexity of the antigenic variation phenomenon in M. gallisepticum is discussed. Images PMID:7523302

  13. Air temperature variations on the Atlantic - Arctic boundary since 1802: the low-frequency pattern and ocean teleconnections

    NASA Astrophysics Data System (ADS)

    Wood, K. R.; Overland, J. E.; Jónsson, T.; Smoliak, B. V.

    2010-12-01

    A two-hundred year instrumental record of annual surface air temperature (SAT) in the Atlantic - Arctic boundary region was reconstructed from four station-based composite time series (Fig. 1). Credibility is supported by ice core records, other temperature proxies, and historical evidence. This record (designated TNA) provides new perspective on past climate fluctuations in a region where pivotal climate system processes occur and where unexplained low-frequency variations were observed during the 20th century. TNA shows that the low-frequency pattern of the 20th century does not have a clear analog in the previous century. During the 19th century decadal-scale climate fluctuations occurred in irregular episodes; none were as distinctive as the early 20th century warming event (~1920 to mid-century), which is the most striking historical feature in the record. Evidence of a strong teleconnection between TNA and SST anomalies in the western boundary current - southern recirculation gyre (WBC) region of the North Atlantic Ocean provides an opportunity to reframe the problem of low-frequency variability in the region in terms tractable to theory and empirical investigation. Positive fluctuations in both TNA (and by extension other climate variables associated with it) and SST in the WBC region could be initiated by persistent variations in the large-scale atmospheric circulation that promote the advection of warm maritime air into the Atlantic - Arctic region and simultaneously limit flux-induced cooling in the Nordic Seas and the WBC/recirculation gyre region. This leads to enhanced ocean heat storage in both regions and may consequently reinforce anomalous atmospheric circulation patterns like those observed during the early 20th century warming event. Figure 1. Extended annual mean SAT record for the Atlantic - Arctic boundary region (TNA). The early 20th century warming (ETCW) episode is marked. Regions represented by station-based composite SAT records used in

  14. Effects of fundamental frequency and duration variation on the perception of South Kyungsang Korean tones.

    PubMed

    Chang, Seung-Eun

    2013-06-01

    The perception of lexical tones is addressed through research on South Kyungsang Korean, spoken in the southeastern part of Korea. Based on an earlier production study (Chang, 2008a, 2008b), a categorization experiment was conducted to determine the perceptually salient aspects of the perceptual nature of a high tone and a rising tone. The experiment tested the perception of isolated synthetic stimuli, in which the crucial acoustic parameters (i.e., timing of F0 peak, initial F0, and syllable duration) were systematically manipulated. The results are generally consistent with the previous production data, showing that these acoustic cues contribute to the perception of two tones, a high tone and a rising tone. The stimulus tends to be identified as a rising tone if the F0 peak is late in the syllable, the initial F0 is low, and the syllable is long, while the stimulus tends to be identified as a high tone if the F0 peak is early in the syllable, the initial F0 is high, and the duration is short. Each of these three parameters, although necessary, did not contribute equally to the perception of tone contrast. Between-subject variation, according to the participant's gender and language background, is also discussed.

  15. Spatial-temporal variation of low-frequency earthquake bursts near Parkfield, California

    USGS Publications Warehouse

    Wu, Chunquan; Guyer, Robert; Shelly, David R.; Trugman, D.; Frank, William; Gomberg, Joan S.; Johnson, P.

    2015-01-01

    Tectonic tremor (TT) and low-frequency earthquakes (LFEs) have been found in the deeper crust of various tectonic environments globally in the last decade. The spatial-temporal behaviour of LFEs provides insight into deep fault zone processes. In this study, we examine recurrence times from a 12-yr catalogue of 88 LFE families with ∼730 000 LFEs in the vicinity of the Parkfield section of the San Andreas Fault (SAF) in central California. We apply an automatic burst detection algorithm to the LFE recurrence times to identify the clustering behaviour of LFEs (LFE bursts) in each family. We find that the burst behaviours in the northern and southern LFE groups differ. Generally, the northern group has longer burst duration but fewer LFEs per burst, while the southern group has shorter burst duration but more LFEs per burst. The southern group LFE bursts are generally more correlated than the northern group, suggesting more coherent deep fault slip and relatively simpler deep fault structure beneath the locked section of SAF. We also found that the 2004 Parkfield earthquake clearly increased the number of LFEs per burst and average burst duration for both the northern and the southern groups, with a relatively larger effect on the northern group. This could be due to the weakness of northern part of the fault, or the northwesterly rupture direction of the Parkfield earthquake.

  16. The relationship between surname frequency and Y chromosome variation in Spain.

    PubMed

    Martinez-Cadenas, Conrado; Blanco-Verea, Alejandro; Hernando, Barbara; Busby, George B J; Brion, Maria; Carracedo, Angel; Salas, Antonio; Capelli, Cristian

    2016-01-01

    In most societies, surnames are passed down from fathers to sons, just like the Y chromosome. It follows that, theoretically, men sharing the same surnames would also be expected to share related Y chromosomes. Previous investigations have explored such relationships, but so far, the only detailed studies that have been conducted are on samples from the British Isles. In order to provide additional insights into the correlation between surnames and Y chromosomes, we focused on the Spanish population by analysing Y chromosomes from 2121 male volunteers representing 37 surnames. The results suggest that the degree of coancestry within Spanish surnames is highly dependent on surname frequency, in overall agreement with British but not Irish surname studies. Furthermore, a reanalysis of comparative data for all three populations showed that Irish surnames have much greater and older surname descent clusters than Spanish and British ones, suggesting that Irish surnames may have considerably earlier origins than Spanish or British ones. Overall, despite closer geographical ties between Ireland and Britain, our analysis points to substantial similarities in surname origin and development between Britain and Spain, while possibly hinting at unique demographic or social events shaping Irish surname foundation and development.

  17. Spatial variations in the frequency-magnitude distribution of earthquakes at Mount Pinatubo volcano

    USGS Publications Warehouse

    Sanchez, J.J.; McNutt, S.R.; Power, J.A.; Wyss, M.

    2004-01-01

    The frequency-magnitude distribution of earthquakes measured by the b-value is mapped in two and three dimensions at Mount Pinatubo, Philippines, to a depth of 14 km below the summit. We analyzed 1406 well-located earthquakes with magnitudes MD ???0.73, recorded from late June through August 1991, using the maximum likelihood method. We found that b-values are higher than normal (b = 1.0) and range between b = 1.0 and b = 1.8. The computed b-values are lower in the areas adjacent to and west-southwest of the vent, whereas two prominent regions of anomalously high b-values (b ??? 1.7) are resolved, one located 2 km northeast of the vent between 0 and 4 km depth and a second located 5 km southeast of the vent below 8 km depth. The statistical differences between selected regions of low and high b-values are established at the 99% confidence level. The high b-value anomalies are spatially well correlated with low-velocity anomalies derived from earlier P-wave travel-time tomography studies. Our dataset was not suitable for analyzing changes in b-values as a function of time. We infer that the high b-value anomalies around Mount Pinatubo are regions of increased crack density, and/or high pore pressure, related to the presence of nearby magma bodies.

  18. Direct, low--frequency scanning capacitance microscopy measurements variations in parasitic capacitance and meniscus formation.

    NASA Astrophysics Data System (ADS)

    Lee, D. T.; Pelz, J. P.; Bhushan, Bharat

    2002-03-01

    We developed a low-noise (<0.4 aF/(Hz)^1/2 at 1 Hz) circuit for direct, calibrated, low-frequency scanning capacitance microscopy (SCM) . We used this circuit to characterize aF-level changes in the parasitic probe-sample capacitance with probe height (2-5 aF/nm) and lateral position (1 ~aF/nm). We also measured the abrupt capacitance change that occurs as the probe tip snaps on/off the surface, which is primarily due to aqueous meniscus formation. For a small meniscus, the capacitance change is a few aF; for a large meniscus, the capacitance change is hundreds of aF. The presence of the meniscus increases the effective area of the capacitance probe, which increases capacitance sensitivity at the expense of spatial resolution. The parasitic capacitance changes and the effect of the meniscus on capacitance must be understood to properly interpret SCM measurements of thin dielectric films, particularly for rough surfaces.

  19. Time-frequency analysis of beach bacteria variations and its implication for recreational water quality modeling.

    PubMed

    Ge, Zhongfu; Frick, Walter E

    2009-02-15

    This paper exploited the potential of the wavelet analysis in resolving beach bacteria concentration and candidate explanatory variables across multiple time scales with temporal information preserved. The wavelet transform of E. coli concentration and its explanatory variables observed at Huntington Beach, Ohio in 2006 exhibited well-defined patterns of different time scales, phases, and durations, which cannot be clearly shown in conventional time-domain analyses. If linear regression modeling is to be used for the ease of implementation and interpretation,the wavelet-transformed regression model reveals that low model residual can be realized through matching major patterns and their phase angles between E. coli concentration and its explanatory variables. The property of pattern matching for linear regression models can be adopted as a criterion for choosing useful predictors, while phase matching further explains why intuitively good variables such as wave height and onshore wind speed were excluded from the optimal models by model selection processes in Frick et al. (Environ. Sci. Technol. 2008, 42,4818-4824). The phase angles defined by the wavelet analysis in the time-frequency domain can help identify the physical processes and interactions occurring between bacteria concentration and its explanatory variables. It was deduced, for this particular case, that wind events resulted in elevated E. coli concentration, wave height, and turbidity at the beach with a periodicity of 7-8 days. Wind events also brought about increased beach bacteria concentrations through large-scale current circulations in the lake with a period of 21 days. The time length for linear regression models with statistical robustness can also be deduced from the periods of the major patterns in bacteria concentration and explanatory variables, which explains and supplements the modeling efforts performed in (1).

  20. Variations in Dream Recall Frequency and Dream Theme Diversity by Age and Sex

    PubMed Central

    Nielsen, Tore

    2012-01-01

    We assessed dream recall frequency (DRF) and dream theme diversity (DTD) with an internet questionnaire among a cohort of 28,888 male and female participants aged 10–79 years in a cross-sectional design. DRF increased from adolescence (ages 10–19) to early adulthood (20–29) and then decreased again for the next 20 years. The nature of this decrease differed for males and females. For males, it began earlier (30–39), proceeded more gradually, and reached a nadir earlier (40–49) than it did for females. For females, it began later (40–49), dropped more abruptly, and reached nadir later (50–59). Marked sex differences were observed for age strata 10–19 through 40–49 and year-by-year analyses estimated the window for these differences to be more precisely from 14 to 44 years. DTD decreased linearly with age for both sexes up to 50–59 and then dropped even more sharply for 60–79. There was a sex difference favoring males on this measure but only for ages 10–19. Findings replicate, in a single sample, those from several previous studies showing an increase in DRF from adolescence to early adulthood, a subsequent decrease primarily in early and middle adulthood, and different patterns of age-related decrease in the two sexes. Age-related changes in sleep structure, such as decreasing %REM sleep which parallel the observed dream recall changes, might help explain these findings, but these sleep changes are much smaller and more gradual in nature. Changes in the phase and amplitude of circadian rhythms of REM propensity and generational differences in life experiences may also account for some part of the findings. That decreases in DTD parallel known age-related decreases in episodic and autobiographical memory may signify that this new diversity measure indexes an aspect of autobiographical memory that also influences dream recall. PMID:22783222

  1. Variational calculation of the limit cycle and its frequency in a two-neuron model with delay

    SciTech Connect

    Brandt, Sebastian F.; Wessel, Ralf; Pelster, Axel

    2006-09-15

    We consider a model system of two coupled Hopfield neurons, which is described by delay differential equations taking into account the finite signal propagation and processing times. When the delay exceeds a critical value, a limit cycle emerges via a supercritical Hopf bifurcation. First, we calculate its frequency and trajectory perturbatively by applying the Poincare-Lindstedt method. Then, the perturbation series are resummed by means of the Shohat expansion in good agreement with numerical values. However, with increasing delay, the accuracy of the results from the Shohat expansion worsens. We thus apply variational perturbation theory (VPT) to the perturbation expansions to obtain more accurate results, which moreover hold even in the limit of large delays.

  2. High frequency variations of the main magnetic field: convergence of observations and theory (Petrus Peregrinus Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Jault, Dominique

    2013-04-01

    Understanding the main magnetic field variations has been hindered by the discrepancy between the periods (from months to years) of the simplest linear wave phenomena and the relatively long time intervals (10 to 100 years) over which magnetic field changes can be confidently monitored. A theoretical description of short-period waves within the Earth's fluid core is at hand. Quasi-geostrophic inertial waves (akin to Rossby waves in the atmosphere) are slightly modified in the presence of magnetic fields and torsional oscillations consist of differential motion between coaxial rigid cylindrical annuli. Torsional oscillations are sensitive to the whole magnetic field that they shear in the course of their propagation. From their modelling, we have thus gained an estimate for the magnetic field strength in the core interior. There is now ongoing work to extend the theoretical framework to longer times. Furthermore, data collected from the Swarm constellation of three satellites to be launched this year by ESA will permit to better separate the internal and external magnetic signals. We may thus dream to detect quasi-geostrophic inertial waves. As the spectral ranges of theoretical models and observations begin to overlap, we can now go beyond the understanding of the magnetic field variations as the juxtaposition of partial models, arranged as a set of nested Matryoshka dolls. This talk will give illustrations for this statement, among which the question of induction in the lower mantle.

  3. High-frequency sea level variations and implications for coastal flooding: A case study of the Solent, UK

    NASA Astrophysics Data System (ADS)

    Ozsoy, Ozgun; Haigh, Ivan D.; Wadey, Matthew P.; Nicholls, Robert J.; Wells, Neil C.

    2016-07-01

    This study examines the occurrence and characteristics of high-frequency (<6 h) sea level variations in the Solent, UK - a mesotidal estuarine strait located in the central English Channel. A 14-year time series (2000-2013) of sea level observations sampled at 15-min intervals from the Southampton tide gauge was analyzed. The 8 highest-energy events have a mean amplitude of approximately 0.6 m and a dominant period of around 4 h. These events correspond with periods of enhanced meteorological activity, namely a marked reduction in air pressure and onset of strong southwesterly-southeasterly winds. Sea level observations from tide gauges around the Solent and the wider English Channel region (23 in total) were used to assess the spatial characteristics of these events. Analysis of time series and phase information indicates the occurrence of standing waves oscillating across the English Channel between southern England and northern France. This study provides a unique example of standing waves generated by extra-tropical cyclones over a large basin (the English Channel) with implications for flood inundation. The event of 28th October 2013 - the highest-amplitude (1.16 m) event in the record - was associated with minor coastal flooding at Yarmouth, Isle of Wight. This flood occurred during a neap tide, when such events are widely thought to be impossible. Hence, our findings emphasize the relevance of high-frequency sea level variability for regional sea level forecasting and flood risk management.

  4. Lateral variations of high-frequency seismic wave propagation at regional distances across the Turkish and Iranian plateaus

    NASA Astrophysics Data System (ADS)

    Kadinsky-Cade, Katharine; Barazangi, Muawia; Oliver, Jack; Isacks, Bryan

    1981-10-01

    In this study we investigate crustal and uppermost mantle physical properties that characterize some of the continental plateaus of the Middle East. This is done as part of a larger effort to map and compare high-frequency wave propagation at regional distances across the earth's continental plateaus. Thousands of short-period WWSSN seismograms recorded at stations located in the Middle East and produced by earthquakes with epicentral distances less than about 20° were examined visually in an effort to study lateral variations of high-frequency (0.5-2 Hz) seismic wave propagation across this area, particularly to the north of the zone of continental collision between the Africa-Arabian and Eurasian plates. Variations of frequencies and amplitudes of Sn and Lg relative to P are examined and mapped throughout the region, and this work is supplemented by a study of velocities of Pn, Sn, and Lg. Sn amplitude variations are very striking in this area. An important observation of this study is that Sn propagates efficiently beneath a major part of the Turkish and Iranian plateaus. Sn is strongly attenuated, however, in the northernmost portion of the plateaus south of the Black and Caspian seas and in an area between the two seas. These regions are characterized, in general, by active tectonism, including volcanism, faulting, and folding. However, this active tectonism is not restricted to the areas of high Sn attenuation but appears to extend beneath other parts of the Iranian and Turkish plateaus. Patterns of lateral variations in the propagation of Lg are not as consistent as those for Sn. Lg propagates efficiently across Turkey, Iran, and adjacent regions, but the Lg waves that cross the Turkish and Iranian plateaus are weak and have relatively long predominant periods of about 2-5 s. The Lg phase is not observed when the path of propagation crosses the southern Caspian and the Black seas, consistent with the evidence of oceanic-type crustal structure beneath these

  5. Separation of the low-frequency atmospheric variability into non-Gaussian multidimensional sources by Independent Subspace Analysis

    NASA Astrophysics Data System (ADS)

    Pires, Carlos; Ribeiro, Andreia

    2016-04-01

    An efficient nonlinear method of statistical source separation of space-distributed non-Gaussian distributed data is proposed. The method relies in the so called Independent Subspace Analysis (ISA), being tested on a long time-series of the stream-function field of an atmospheric quasi-geostrophic 3-level model (QG3) simulating the winter's monthly variability of the Northern Hemisphere. ISA generalizes the Independent Component Analysis (ICA) by looking for multidimensional and minimally dependent, uncorrelated and non-Gaussian distributed statistical sources among the rotated projections or subspaces of the multivariate probability distribution of the leading principal components of the working field whereas ICA restrict to scalar sources. The rationale of that technique relies upon the projection pursuit technique, looking for data projections of enhanced interest. In order to accomplish the decomposition, we maximize measures of the sources' non-Gaussianity by contrast functions which are given by squares of nonlinear, cross-cumulant-based correlations involving the variables spanning the sources. Therefore sources are sought matching certain nonlinear data structures. The maximized contrast function is built in such a way that it provides the minimization of the mean square of the residuals of certain nonlinear regressions. The issuing residuals, followed by spherization, provide a new set of nonlinear variable changes that are at once uncorrelated, quasi-independent and quasi-Gaussian, representing an advantage with respect to the Independent Components (scalar sources) obtained by ICA where the non-Gaussianity is concentrated into the non-Gaussian scalar sources. The new scalar sources obtained by the above process encompass the attractor's curvature thus providing improved nonlinear model indices of the low-frequency atmospheric variability which is useful since large circulation indices are nonlinearly correlated. The non-Gaussian tested sources (dyads and

  6. Multi-frequency inversion-charge pumping for charge separation and mobility analysis in high-k/InGaAs metal-oxide-semiconductor field-effect transistors

    SciTech Connect

    Djara, V.; Cherkaoui, K.; Negara, M. A.; Hurley, P. K.

    2015-11-28

    An alternative multi-frequency inversion-charge pumping (MFICP) technique was developed to directly separate the inversion charge density (N{sub inv}) from the trapped charge density in high-k/InGaAs metal-oxide-semiconductor field-effect transistors (MOSFETs). This approach relies on the fitting of the frequency response of border traps, obtained from inversion-charge pumping measurements performed over a wide range of frequencies at room temperature on a single MOSFET, using a modified charge trapping model. The obtained model yielded the capture time constant and density of border traps located at energy levels aligned with the InGaAs conduction band. Moreover, the combination of MFICP and pulsed I{sub d}-V{sub g} measurements enabled an accurate effective mobility vs N{sub inv} extraction and analysis. The data obtained using the MFICP approach are consistent with the most recent reports on high-k/InGaAs.

  7. Yearly variation of spontaneous somatic mutation frequency in the stamen hairs of Tradescantia clone KU 9 grown outdoors, which showed a significant increase after the Chernobyl accident.

    PubMed

    Ichikawa, S; Nakano, A; Kenmochi, M; Yamamoto, I; Murai, M; Takahashi, E; Yamaguchi, A; Watanabe, K; Tomiyama, M; Sugiyama, K; Yogo, A; Yazaki, T; Okumura, M; Shima, N; Satoh, M; Yoshimoto, M; Xiao, L Z

    1996-02-01

    Scoring of spontaneous somatic pink mutation frequency in the stamen hairs of Tradescantia clone KU 9, a heterozygote for flower color (blue/pink; the blue color being dominant), was carried out for 11 years on plants grown outdoors, during the period of May 11-31 (for 3 weeks) in every year from 1982 to 1992. Weekly and yearly variations of the spontaneous mutation frequency were observed, and such variations could mostly be correlated to the difference in temperature. That is, the mutation frequency was generally higher in the weeks and years when the temperature was relatively low, showing the strongest negative correlation with the average minimum temperature. The variations were also correlated to the diurnal temperature difference, the mutation frequency being higher with larger diurnal temperature difference in general. However, the mutation frequency observed in 1986 was exceptionally higher than that expected from the temperature for this year, and was very significantly higher than for other years. The scoring of mutation frequency was thus continued in 1986 for an additional 4 weeks (June 1-28), and it was confirmed that such higher mutation frequencies lasted for 6 weeks in total. The exceptionally high mutation frequency seemed to be related to the radioactive fallout which occurred in early to mid May of 1986, even in Japan, after the serious nuclear reactor accident at Chernobyl, and also to the biological concentrations of radioactive nuclides which subsequently occurred, although it was difficult to conclude this definitely. The mutation frequency in 1987 was second highest, and was also significantly higher than the lowest mutation frequency observed in 1990. PMID:8600356

  8. Yearly variation of spontaneous somatic mutation frequency in the stamen hairs of Tradescantia clone KU 9 grown outdoors, which showed a significant increase after the Chernobyl accident.

    PubMed

    Ichikawa, S; Nakano, A; Kenmochi, M; Yamamoto, I; Murai, M; Takahashi, E; Yamaguchi, A; Watanabe, K; Tomiyama, M; Sugiyama, K; Yogo, A; Yazaki, T; Okumura, M; Shima, N; Satoh, M; Yoshimoto, M; Xiao, L Z

    1996-02-01

    Scoring of spontaneous somatic pink mutation frequency in the stamen hairs of Tradescantia clone KU 9, a heterozygote for flower color (blue/pink; the blue color being dominant), was carried out for 11 years on plants grown outdoors, during the period of May 11-31 (for 3 weeks) in every year from 1982 to 1992. Weekly and yearly variations of the spontaneous mutation frequency were observed, and such variations could mostly be correlated to the difference in temperature. That is, the mutation frequency was generally higher in the weeks and years when the temperature was relatively low, showing the strongest negative correlation with the average minimum temperature. The variations were also correlated to the diurnal temperature difference, the mutation frequency being higher with larger diurnal temperature difference in general. However, the mutation frequency observed in 1986 was exceptionally higher than that expected from the temperature for this year, and was very significantly higher than for other years. The scoring of mutation frequency was thus continued in 1986 for an additional 4 weeks (June 1-28), and it was confirmed that such higher mutation frequencies lasted for 6 weeks in total. The exceptionally high mutation frequency seemed to be related to the radioactive fallout which occurred in early to mid May of 1986, even in Japan, after the serious nuclear reactor accident at Chernobyl, and also to the biological concentrations of radioactive nuclides which subsequently occurred, although it was difficult to conclude this definitely. The mutation frequency in 1987 was second highest, and was also significantly higher than the lowest mutation frequency observed in 1990.

  9. The variations of ionosphere critical frequency of E layer over the equatorial geomagnetic region in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Kenpankho, Prasert; Ishii, Mamoru; Supnithi, Pornchai

    2016-07-01

    We investigate the values of the critical frequency of the ionospheric E layer, foE, obtained at Chumphon ionospheric observatory station, Thailand. For a declining phase of the solar cycle 23 during the year 2005-2008 and an inclining phase of the solar cycle 24 during the year 2009-2013, the foE data have been used to investigate the foE variations over the equatorial geomagnetic region in Southeast Asia. A comparison between the observation data and International Reference Ionosphere (IRI) 2012 model has also been investigated and studied. The results show that the foE obtained from IRI 2012 model underestimates foE from Chumphon station especially during the period of 7-11 am and after 6 pm for each day and all seasons. As the results combining with the previous investigations, we suggest that the underestimation of ionospheric foE by IRI 2012 model is helpful for the correction and improvement of IRI model in an equatorial Asia region.

  10. Response of a hydrothermal system to magmatic heat inferred from temporal variations in the complex frequencies of long-period events at Kusatsu-Shirane Volcano, Japan

    USGS Publications Warehouse

    Nakano, M.; Kumagai, H.

    2005-01-01

    We investigate temporal variations in the complex frequencies (frequency and quality factor Q) of long-period (LP) events that occurred at Kusatsu-Shirane Volcano, central Japan. We analyze LP waveforms observed at this volcano in the period between 1988 and 1995, which covers a seismically active period between 1989 and 1993. Systematic temporal variations in the complex frequencies are observed in October-November 1989, July-October 1991, and September 1992-January 1993. We use acoustic properties of a crack filled with hydrothermal fluids to interpret the observed temporal variations in the complex frequencies. The temporal variations in October-November 1989 can be divided into two periods, which are explained by a gradual decrease and increase of a gas-volume fraction in a water-steam mixture in a crack, respectively. The temporal variations in July-October 1991 can be also divided into two periods. These variations in the first and second periods are similar to those observed in November 1989 and in September-November 1992, respectively, and are interpreted as drying of a water-steam mixture and misty gas in a crack, respectively. The repeated nature of the temporal variations observed in similar seasons between July and November suggests the existence of seasonality in the occurrence of LP events. This may be caused by a seasonally variable meteoritic water supply to a hydrothermal system, which may have been heated by the flux of volcanic gases from magma beneath this volcano. ?? 2005 Elsevier B.V. All rights reserved.

  11. Detecting changes in respiratory patterns in high frequency chest compression therapy by single-channel blind source separation.

    PubMed

    Zhu, Xiaoming; Parhi, Keshab K; Warwick, Warren J

    2009-01-01

    High Frequency Chest Compression (HFCC) is used as a method to remove the mucus in the airway for Cystic Fibrosis (CF) patients. As the characteristics of the tracheal sound reflect the conditions of airways, in this paper, we propose a novel method to evaluate the respiratory patterns in HFCC therapy by using single channel tracheal sounds only. The difficulty of analyzing tracheal sounds lies in that it has a wider frequency band than the air flow at the mouth, and is always corrupted by other biomedical signals and noises. During HFCC therapy, the tracheal sound is also affected by the HFCC machine noise. For this reason, it is difficult to extract respiratory patterns and other related features by traditional filtering techniques. In this paper, we demonstrate use of single-channel independent component analysis to extract respiratory patterns from the tracheal sounds before, during and after HFCC therapy, and use basis features in the tracheal sound to detect the change in respiratory patterns.

  12. Learning to be different: Acquired skills, social learning, frequency dependence, and environmental variation can cause behaviourally mediated foraging specializations

    USGS Publications Warehouse

    Tinker, M.T.; Mangel, M.; Estes, J.A.

    2009-01-01

    ) Offspring can learn foraging skills from their mothers (matrilineal social learning). (6) Food abundance is limited, such that average individual energy reserves are low Additionally, the following factors increase the likelihood of alternative specializations co-occurring in a predator population: (1) The predator exerts effective top-down control of prey abundance, resulting in frequency-dependent dynamics. (2) There is stochastic Variation in prey population dynamics, but this Variation is neither too extreme in magnitude nor too 'slow' with respect to the time required for an individual forager to learn new foraging skills. For a given predator population, we deduce that the degree of specialization will be highest for those prey types requiring complex capture or handling skills, while prey species that are both profitable and easy to capture and handle will be included in the diet of all individuals. Frequency-dependent benefits of selecting alternative prey types, combined with the ability of foragers to improve their foraging skills by learning, and transmit learned skills to offspring, can result in behaviourally mediated foraging specialization, and also lead to the co-existence of alternative specializations. The extent of such specialization is predicted to be a variable trait, increasing in locations or years when intra-specific competition is high relative to inter-specific competition. ?? 2009 M. Tim Tinker.

  13. Antigen heterogeneity among isolates of Mycoplasma bovis is generated by high-frequency variation of diverse membrane surface proteins.

    PubMed Central

    Rosengarten, R; Behrens, A; Stetefeld, A; Heller, M; Ahrens, M; Sachse, K; Yogev, D; Kirchhoff, H

    1994-01-01

    The protein and antigen profiles of 11 isolates of Mycoplasma bovis were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis of whole organisms. The isolates examined included the type strain PG45 and 10 other filter-cloned strains or purified isolates both from animals without clinical signs and from clinical cases of bovine mastitis, arthritis, or pneumonia. While the overall protein patterns visualized by silver staining were very similar, marked differences in the antigen banding profiles were detected by rabbit antiserum prepared against whole organisms from one of the strains analyzed. This antigenic heterogeneity was shown to be independent of the geographical origin, the type of clinical disease, and the site of isolation and was also observed among serial isolates from a single animal. Antigen profiles were further monitored throughout sequentially subcloned populations of the PG45 strain. This clonal analysis revealed a high-frequency variation in the expression levels of several prominent antigens. All of these variable antigens were defined by detergent-phase fractionation with Triton X-114 as amphiphilic integral membrane proteins. A subset of different-sized membrane proteins was identified by a monoclonal antibody raised against a PG45 subclone expressing a 63- and a 46-kDa variant antigen within that set. The selective susceptibility of these proteins to trypsin treatment of intact organisms and their ability to bind the monoclonal antibody in colony immunoblots demonstrated that they were exposed on the cell surface. In addition, their preferential recognition by serum antibodies from individual cattle with naturally induced M. bovis mastitis or arthritis confirmed that they were major immunogens of this organism. These studies establish that the apparent antigenic heterogeneity among M. bovis isolates reported here does not represent stable phenotypic strain differences generated from accumulated

  14. Separating components of variation in measurement series using maximum likelihood estimation. Application to patient position data in radiotherapy

    NASA Astrophysics Data System (ADS)

    Sage, J. P.; Mayles, W. P. M.; Mayles, H. M.; Syndikus, I.

    2014-10-01

    Maximum likelihood estimation (MLE) is presented as a statistical tool to evaluate the contribution of measurement error to any measurement series where the same quantity is measured using different independent methods. The technique was tested against artificial data sets; generated for values of underlying variation in the quantity and measurement error between 0.5 mm and 3 mm. In each case the simulation parameters were determined within 0.1 mm. The technique was applied to analyzing external random positioning errors from positional audit data for 112 pelvic radiotherapy patients. Patient position offsets were measured using portal imaging analysis and external body surface measures. Using MLE to analyze all methods in parallel it was possible to ascertain the measurement error for each method and the underlying positional variation. In the (AP / Lat / SI) directions the standard deviations of the measured patient position errors from portal imaging were (3.3 mm / 2.3 mm / 1.9 mm), arising from underlying variations of (2.7 mm / 1.5 mm / 1.4 mm) and measurement uncertainties of (1.8 mm / 1.8 mm / 1.3 mm), respectively. The measurement errors agree well with published studies. MLE used in this manner could be applied to any study in which the same quantity is measured using independent methods.

  15. Dynamics of an enzyme polymorphism in the isopod, Sphaeroma rugicauda (Leach). I. Temporal variation in genotype frequencies.

    PubMed

    Edwards, J P; Heath, D J

    1983-10-01

    A 27 month study (November, 1978 through January, 1981) of the diallelic enzyme locus, phosphoglucose isomerase (Pgi), in the estuarine isopod Sphaeroma rugicauda (Leach) revealed seasonal changes in the frequencies of the three genotypes (fast/fast, fast/slow and slow/slow). A comparison of genotype frequencies in the newly-released offspring (August) to the frequencies in the same animals ten months later during the breeding season (June), revealed a decline in heterozygote frequency and a corresponding increase in the frequency of the s/s homozygote both of which appeared to be initiated at the onset of winter, a period characterised by low temperatures and salinity. Survivorship experiments in the laboratory suggested that the increase in frequency of the s/s homozygote, at least, could be explained by this genotype being favoured at low temperatures.

  16. EXPERIMENTAL-BASED DISCUSSION FOR THE SEPARATION OF RESIDUAL STRESSES AND COLD WORK IN SHOT PEENED IN718 USING HIGH FREQUENCY EDDY CURRENT SPECTROSCOPY

    SciTech Connect

    Hillmann, S.; Heuer, H.; Robbert, A.; Meyendorf, N.; Baron, H.-U.; Bamberg, J.

    2010-02-22

    Typical aero engine alloys, such as IN718, can be surface-treated by shot peening to induce near-surface compressive strains. To calculate the remaining operation time for those critical aero engine components, a quantitative nondestructive determination of near-surface strain gradients has to be developed. We have demonstrated in the past, that it is possible to obtain a characteristic depth profile (surface and sub-surface) of the electrical conductivity of shot peened specimen by using high-frequency eddy current techniques. The measured conductivity profile is resulting from residual stresses, cold work, surface roughness, and the microstructure of the material. The objective is to measure residual stresses (separately from other material properties) in such components after a defined life time. It can be assumed, that surface roughness and microstructure remain unchanged in IN718 materials over their lifetime, but cold work and residual stresses can change independently. Consequently, there is a need to clearly separate the information from both material properties of received eddy current conductivity signals in order to obtain specific information related to residual stresses. This paper presents results acquired from different experiments, conducted to separate both effects by using the eddy current technique on shot peened IN718 materials. We present different physical approaches and illustrate the experiments to solve them. In addition, we will demonstrate that there is a need to use additional techniques, for example ultrasonic time-of-flight measurements, to separate the effects of residual stresses from compound (mixed) signals obtained on cold work samples.

  17. Variations of boundary reaction rate and particle size on the diffusion-induced stress in a phase separating electrode

    SciTech Connect

    Zhang, Lei; He, Linghui; Ni, Yong; Song, Yicheng

    2014-10-14

    In contrast to the case of single-phase delithiation wherein faster discharging leads to higher diffusion-induced stress (DIS), this paper reports nonmonotonous dependency of the boundary reaction rate on the DIS in nanosized spherical electrode accompanying phase separation. It is attributed to a transition from two-phase to single-phase delithiation driven by increase of the boundary reaction rate leading to narrowing and vanishing of the miscibility gap in a range of the particle size. The profiles of lithium concentration and the DIS are identified during the transition based on a continuum model. The resultant maximum DIS first decreases in the region of two-phase delithiation and later returns to increase in the region of single-phase delithiation with the increase of the boundary reaction rate. A map for the failure behavior in the spherical electrode particle is constructed based on the Tresca failure criterion. These results indicate that the failure caused by the DIS can be avoided by appropriate selection of the said parameters in such electrodes.

  18. Analysis of genetic and environmental sources of variation in serum cholesterol in Tecumseh, Michigan. I. Analysis of the frequency distribution for evidence of a genetic polymorphism.

    PubMed Central

    Sing, C F; Chamberlain, M A; Block, W D; Feiler, S

    1975-01-01

    Analyses of serum cholesterol measurements on 4,619 males and 4,730 females residing in the community of Tecumseh, Michigan, were conducted to estimate the contribution of sex, age, temporal variation, and bimodality to determining the normal variation among individuals sampled without regard to their health status. Female values had a higher mean (2.8 mg/100 ml greater) but smaller variance than males when adjusted by polynomial regression to a common age. Positive skew in the frequency distribution for both sexes was removed by natural logarithm (ln) transformation. Age variation accounted for 28.5% and 29.4% of the variance in a ln cholesterol measurement of males and females, respectively. Between 7% and 10% of the variance in a ln cholesterol value was estimated to be attributable to differences between age-adjusted replicate measurements of the same individual. The reduction in individual variability by adjustment for these contributions to variance will allow a more precise evaluation of the relative contribution of alternate genetic hypotheses as explanations for normal variation in cholesterol. Assuming bimodality, approximately one in 1,000 males and one in 1,000 females belong to a second mode of hypercholesterolemic individuals. The locus determining familial hypercholesterolemia is not a major source of normal phenotypic variation in the Tecumseh population. PMID:803015

  19. Haemoglobin polymorphism in atlantic cod (Gadus morhua): Allele frequency variation between yearclasses in a Norwegian fjord stock

    NASA Astrophysics Data System (ADS)

    Mork, J.; Sundnes, G.

    1985-03-01

    A total of 262 specimens (0-, and 1-group) of Atlantic cod (Gadus morhua) representing 4 different yearclasses were caught in Trondheimsfjorden, Norway, during 1977 1984. They were genotyped by agar gel electrophoresis for the polymorphic haemoglobin locus HbI (Sick, 1961). The analyses revealed a highly significant (P=0.0003) heterogeneity of HbI allele frequencies between yearclasses. The difference in the frequency of the HbI-1 allele between the first (1977) and the last (1983) yearclass amounted to 0.18 (±0.07). The results appear to support recent reports on considerable selection effects at HbI, and stress the unreliability of allele frequencies at this locus for use in studies of the genetic population structure of cod.

  20. Longitudinal variations of very-low-frequency chorus activity in the magnetosphere - Evidence of excitation by electrical power transmission lines

    NASA Technical Reports Server (NTRS)

    Luette, J. P.; Park, C. G.; Helliwell, R. A.

    1977-01-01

    The distribution of VLF chorus in the high-altitude magnetosphere as detected by the Ogo 3 satellite was investigated. Chorus occurrence frequency over 4,668 samples of 5 min of broadband data was computed for Northern Hemisphere bins of 10 deg by 10 deg in dipole invariant latitude and longitude. Peaks in activity were noted over Alaska, the eastern U.S. and Canada, western Europe, and western Siberia, and were shown not to be the result of biased sampling. It is suggested that power line radiation of only about 1 W or less at a given harmonic frequency may be sufficient to stimulate the observed chorus activity and that such power levels can be expected in industrial areas or from large distribution networks. Preliminary results show that chorus starting frequencies are highly correlated with 60 Hz harmonics in the American sector and with 50 Hz harmonics in the European sector.

  1. The pulse amplitude variation with QPO frequency in SAX J1808.4-3658: Resonances with the accretion disk

    NASA Astrophysics Data System (ADS)

    Caliskan, Sirin; Alpar, Mehmet Ali; Sasmaz Mus, Sinem

    2016-07-01

    SAX J1808.4-3658 is an accreting millisecond pulsar with a spin period of 401 Hz. The pulsed amplitudes of this source vary with its kHz QPO frequencies (Bult & van der Klis 2015). The pulsed amplitude peaks at certain upper kHz QPO frequencies which we associate with boundary layer modes of the viscous accretion disk (Erkut et al. 2008). We model this as peaks in the energy dissipation rate at the accretion caps due to resonances between the accretion column and the driving modes of the boundary layer.

  2. Frequency variations of quasi-periodic ELF-VLF emissions: A possible new ground-based diagnostic of the outer high-latitude magnetosphere

    SciTech Connect

    Alford, J.; Engebretson, M.; Arnoldy, R.; Inan, U.

    1996-01-01

    Magnetic pulsations and quasi-periodic (QP) amplitude modulations of ELF-VLF waves at Pc 3-4 frequencies (15-50 mHz) are commonly observed simultaneously in cusp-latitude data. The naturally occurring ELF-VLF emissions are believed to be modulated within the magnetosphere by the compressional component of geomagnetic pulsations formed external to the magnetosphere. The authors have examined data from South Pole Station (L {approximately} 14) to determine the occurrence and characteristics of QP emissions. On the basis of 14 months of data during 1987 and 1988 they found that QP emissions typically appeared in both the 0.5-1 kHz and 1-2 kHz receiver channels at South Pole Station and ocassionally in the 2-4 kHz channel. The QP emission frequency appeared to depend on solar wind parameters and interplanetary magnetic field (IMF) direction, and the months near fall equinox in both 1987 and 1988 showed a significant increase in the percentage of QP emissions only in the lowest-frequency channel. The authors present a model consistent with these variations in which high-latitude (nonequatorial) magnetic field minima near the magnetopause play a major role, because the field magnitude governs both the frequency of ELF-VLF emissions and the whistler mode propagation cutoffs. Because the field in these regions will be strongly influenced by solar wind and IMF parameters, variations in the frequency of such emissions may be useful in providing ground-based diagnostics of the outer high-latitude magnetosphere. 32 refs., 13 figs.

  3. Effects of exposure time on variations in the structure and hydrophobicity of polyvinylidene fluoride membranes prepared via vapor-induced phase separation

    NASA Astrophysics Data System (ADS)

    Peng, Yuelian; Fan, Hongwei; Dong, Yajun; Song, Yanna; Han, Hua

    2012-08-01

    The present investigation revealed how the surface morphology and hydrophobicity of polyvinylidene fluoride (PVDF) membranes, which were prepared via a vapor-induced phase separation (VIPS) method, were affected by the exposure time. The mass variation of the cast film was recorded. Membrane morphologies were observed by scanning electron microscopy (SEM) and thermal behaviors of membranes were examined by differential scanning calorimetry (DSC). Wide angle X-ray diffraction (WAXD) was employed to analyze the crystalline structures of the overall membranes and the surface layers. The results showed that different membrane morphologies and hydrophobicities could be obtained by changing the exposure time. A long exposure time facilitated the crystallization process, resulting in the formation of a porous skin and particle morphology, which increased the hydrophobicity of the surface. A short exposure time favored the formation of a digitate macrovoid and dense skin resulting from liquid-liquid phase separation in the immersion process, which reduced surface hydrophobicity. The water permeate flux in vacuum membrane distillation was greatly affected by the membrane porosity and surface hydrophobicity.

  4. Separating water-potential induced swelling and shrinking from measured radial stem variations reveals a cambial growth and osmotic concentration signal.

    PubMed

    Chan, Tommy; Hölttä, Teemu; Berninger, Frank; Mäkinen, Harri; Nöjd, Pekka; Mencuccini, Maurizio; Nikinmaa, Eero

    2016-02-01

    The quantification of cambial growth over short time periods has been hampered by problems to discern between growth and the swelling and shrinking of a tree stem. This paper presents a model, which separates cambial growth and reversible water-potential induced diurnal changes from simultaneously measured whole stem and xylem radial variations, from field-measured Scots pine trees in Finland. The modelled growth, which includes osmotic concentration changes, was compared with (direct) dendrometer measurements and microcore samples. In addition, the relationship of modelled growth and dendrometer measurements to environmental factors was analysed. The results showed that the water-potential induced changes of tree radius were successfully separated from stem growth. Daily growth predicted by the model exhibited a high correlation with the modelled daily changes of osmotic concentration in phloem, and a temperature dependency in early summer. Late-summer growth saw higher dependency on water availability and temperature. Evaluation of the model against dendrometer measurements showed that the latter masked a true environmental signal in stem growth due to water-potential induced changes. The model provides better understanding of radial growth physiology and offers potential to examine growth dynamics and changes due to osmotic concentration, and how the environment affects growth.

  5. Separating water-potential induced swelling and shrinking from measured radial stem variations reveals a cambial growth and osmotic concentration signal.

    PubMed

    Chan, Tommy; Hölttä, Teemu; Berninger, Frank; Mäkinen, Harri; Nöjd, Pekka; Mencuccini, Maurizio; Nikinmaa, Eero

    2016-02-01

    The quantification of cambial growth over short time periods has been hampered by problems to discern between growth and the swelling and shrinking of a tree stem. This paper presents a model, which separates cambial growth and reversible water-potential induced diurnal changes from simultaneously measured whole stem and xylem radial variations, from field-measured Scots pine trees in Finland. The modelled growth, which includes osmotic concentration changes, was compared with (direct) dendrometer measurements and microcore samples. In addition, the relationship of modelled growth and dendrometer measurements to environmental factors was analysed. The results showed that the water-potential induced changes of tree radius were successfully separated from stem growth. Daily growth predicted by the model exhibited a high correlation with the modelled daily changes of osmotic concentration in phloem, and a temperature dependency in early summer. Late-summer growth saw higher dependency on water availability and temperature. Evaluation of the model against dendrometer measurements showed that the latter masked a true environmental signal in stem growth due to water-potential induced changes. The model provides better understanding of radial growth physiology and offers potential to examine growth dynamics and changes due to osmotic concentration, and how the environment affects growth. PMID:25808847

  6. Modelling of human low frequency sound localization acuity demonstrates dominance of spatial variation of interaural time difference and suggests uniform just-noticeable differences in interaural time difference.

    PubMed

    Smith, Rosanna C G; Price, Stephen R

    2014-01-01

    Sound source localization is critical to animal survival and for identification of auditory objects. We investigated the acuity with which humans localize low frequency, pure tone sounds using timing differences between the ears. These small differences in time, known as interaural time differences or ITDs, are identified in a manner that allows localization acuity of around 1° at the midline. Acuity, a relative measure of localization ability, displays a non-linear variation as sound sources are positioned more laterally. All species studied localize sounds best at the midline and progressively worse as the sound is located out towards the side. To understand why sound localization displays this variation with azimuthal angle, we took a first-principles, systemic, analytical approach to model localization acuity. We calculated how ITDs vary with sound frequency, head size and sound source location for humans. This allowed us to model ITD variation for previously published experimental acuity data and determine the distribution of just-noticeable differences in ITD. Our results suggest that the best-fit model is one whereby just-noticeable differences in ITDs are identified with uniform or close to uniform sensitivity across the physiological range. We discuss how our results have several implications for neural ITD processing in different species as well as development of the auditory system.

  7. Genetic control of mammalian meiotic recombination. I. Variation in exchange frequencies among males from inbred mouse strains.

    PubMed

    Koehler, Kara E; Cherry, Jonathan P; Lynn, Audrey; Hunt, Patricia A; Hassold, Terry J

    2002-09-01

    Genetic background effects on the frequency of meiotic recombination have long been suspected in mice but never demonstrated in a systematic manner, especially in inbred strains. We used a recently described immunostaining technique to assess meiotic exchange patterns in male mice. We found that among four different inbred strains--CAST/Ei, A/J, C57BL/6, and SPRET/Ei--the mean number of meiotic exchanges per cell and, thus, the recombination rates in these genetic backgrounds were significantly different. These frequencies ranged from a low of 21.5 exchanges in CAST/Ei to a high of 24.9 in SPRET/Ei. We also found that, as expected, these crossover events were nonrandomly distributed and displayed positive interference. However, we found no evidence for significant differences in the patterns of crossover positioning between strains with different exchange frequencies. From our observations of >10,000 autosomal synaptonemal complexes, we conclude that achiasmate bivalents arise in the male mouse at a frequency of 0.1%. Thus, special mechanisms that segregate achiasmate chromosomes are unlikely to be an important component of mammalian male meiosis.

  8. Time variation in the low-frequency spectrum of Vela-like pulsar B1800-21

    NASA Astrophysics Data System (ADS)

    Basu, Rahul; Rożko, Karolina; Lewandowski, Wojciech; Kijak, Jarosław; Dembska, Marta

    2016-05-01

    We report the flux measurement of the Vela-like pulsar B1800-21 at the low radio frequency regime over multiple epochs spanning several years. The spectrum shows a turnover around the GHz frequency range and represents a typical example of gigahertz-peaked spectrum (GPS) pulsar. Our observations revealed that the pulsar spectrum show a significant evolution during the observing period with the low-frequency part of the spectrum becoming steeper, with a higher turnover frequency, for a period of several years before reverting back to the initial shape during the latest measurements. The spectral change over times spanning several years requires dense structures, with free electron densities around 1000-20 000 cm-3 and physical dimensions ˜220 au, in the interstellar medium (ISM) traversing across the pulsar line of sight. We look into the possible sites of such structures in the ISM and likely mechanisms particularly the thermal free-free absorption as possible explanations for the change.

  9. The Tracking Study: Description of a randomized controlled trial of variations on weight tracking frequency in a behavioral weight loss program

    PubMed Central

    Linde, Jennifer A.; Jeffery, Robert W.; Crow, Scott J.; Brelje, Kerrin L.; Pacanowski, Carly R.; Gavin, Kara L.; Smolenski, Derek J.

    2014-01-01

    Observational evidence from behavioral weight control trials and community studies suggests that greater frequency of weighing oneself, or tracking weight, is associated with better weight outcomes. Conversely, it has also been suggested that frequent weight tracking may have a negative impact on mental health and outcomes during weight loss, but there are minimal experimental data that address this concern in the context of an active weight loss program. To achieve the long-term goal of strengthening behavioral weight loss programs, the purpose of this randomized controlled trial (the Tracking Study) is to test variations on frequency of self-weighing during a behavioral weight loss program, and to examine psychosocial and mental health correlates of weight tracking and weight loss outcomes. Three hundred thirty-nine overweight and obese adults were recruited and randomized to one of three variations on weight tracking frequency during a 12-month weight loss program with a 12-month follow-up: daily weight tracking, weekly weight tracking, or no weight tracking. The primary outcome is weight in kilograms at 24 months. The weight loss program integrates each weight tracking instruction with standard behavioral weight loss techniques (goal setting, self-monitoring, stimulus control, dietary and physical activity enhancements, lifestyle modifications); participants in weight tracking conditions were provided with wireless Internet technology (Wi-Fi-enabled digital scales and touchscreen personal devices) to facilitate weight tracking during the study. This paper describes the study design, intervention features, recruitment, and baseline characteristics of participants enrolled in the Tracking Study. PMID:25533727

  10. Annual variations of the amplitude characteristic of the noise magnetic field in the ELF frequency range based on the results of high-latitude observations

    NASA Astrophysics Data System (ADS)

    Pchelkin, V. V.

    2014-09-01

    The annual variation of a number of amplitude characteristics of the noise electromagnetic field in the frequency range near the first Schumann resonance (and in particular the mean values of the modulus of horizontal magnetic components and parameters of the distribution function of noise pulses over amplitudes) was obtained and analyzed based on the results of three-year measurements performed at the high-latitude magnetic observatory Lovozero. The summer increase in mean and median values of the magnetic component of noises associated with electrical storms and the lack of annual variations of the exponent that empirically describes the distribution of amplitudes of noise signals were found. The relationship between the seasonal (winter/summer in the northern hemisphere) increase in the mean value of the modulus of the horizontal magnetic field component and seasonal increase in the global number of lightning discharges is shown by the correlation of the results of satellite observations and measurements of the magnetic component.

  11. A comparison of low-frequency variations in two data series on the coordinates of the Earth's pole

    NASA Astrophysics Data System (ADS)

    Kurbasova, G. S.; Korsun', A. A.; Rykhlova, L. V.; Rybalova, M. N.; Shlikar', G. N.

    1997-09-01

    A comparison of two data series on the Earth's polar oscillations at low frequencies (lower than the Chandler oscillation frequency) are discussed. One of these data series was processed in the CIO frame, and the other was processed using a new global determination of the Earth orientation parameters. Linear trends were first extracted and compared. The constant relative shift between the series is 0.02" and the shift of their slopes does not exceed 0.012" per century. An earlier comparison of the main periodic components (Chandler wobble and the annual component) using the same data series did not reveal any substantial discrepancies in the struc- ture of the oscillations. The most prominent oscillations at low frequencies, with periods 42.67 and 6.40 yr, were chosen for the comparison. A two-channel autoregression analysis indicates a phase shift: the oscillations of the coordinates of the Earth's pole with period 42.67 yr in the two data series are shifted relative to each other by 0.53 yr, and the oscillations with period 6.4 yr are shifted by 0.33 yr. An interrelation in phase space was found: the displacement curve for the equilibrium centers for six-year Poincare mapping sections has a period of 42.7 year.

  12. Localized frameshift mutation generates selective, high-frequency phase variation of a surface lipoprotein encoded by a mycoplasma ABC transporter operon.

    PubMed Central

    Theiss, P; Wise, K S

    1997-01-01

    The wall-less mycoplasmas have revealed unusual microbial strategies for adaptive variation of antigenic membrane proteins exposed during their surface colonization of host cells. In particular, high-frequency mutations affecting the expression of selected surface lipoproteins have been increasingly documented for this group of organisms. A novel manifestation of mutational phase variation is shown here to occur in Mycoplasma fermentans, a chronic human infectious agent and possible AIDS-associated pathogen. A putative ABC type transport operon encoding four gene products is identified. The 3' distal gene encoding P78, a known surface-exposed antigen and the proposed substrate-binding lipoprotein of the transporter, is subject to localized hypermutation in a short homopolymeric tract of adenine residues located in the N-terminal coding region of the mature product. High-frequency, reversible insertion/deletion frameshift mutations lead to selective phase variation in P78 expression, whereas the putative nucleotide-binding protein, P63, encoded by the most 5' gene of the operon, is continually expressed. Mutation-based phase variation in specific surface-exposed microbial transporter components may provide an adaptive advantage for immune evasion, while continued expression of other elements of the same transporter may preserve essential metabolic functions and confer alternative substrate specificity. These features could be critical in mycoplasmas, where limitations in both transcriptional regulators and transport systems may prevail. This study also documents that P63 contains an uncharacteristic hydrophobic sequence between predicted nucleotide binding motifs and displays an amphiphilic character in detergent fractionation. Both features are consistent with an evolutionary adaptation favoring integral association of this putative energy-transducing component with the single mycoplasma membrane. PMID:9190819

  13. Binary frequency of planet-host stars at wide separations. A new brown dwarf companion to a planet-host star

    NASA Astrophysics Data System (ADS)

    Lodieu, N.; Pérez-Garrido, A.; Béjar, V. J. S.; Gauza, B.; Ruiz, M. T.; Rebolo, R.; Pinfield, D. J.; Martín, E. L.

    2014-09-01

    Aims: The aim of the project is to improve our knowledge on the multiplicity of planet-host stars at wide physical separations. Methods: We cross-matched approximately 6200 square degree area of the southern sky imaged by the Visible Infrared Survey Telescope for Astronomy (VISTA) Hemisphere Survey (VHS) with the Two Micron All Sky Survey (2MASS) to look for wide common proper motion companions to known planet-host stars. We complemented our astrometric search with photometric criteria. Results: We confirmed spectroscopically the co-moving nature of seven sources out of 16 companion candidates and discarded eight, while the remaining one stays as a candidate. Among these new wide companions to planet-host stars, we discovered a T4.5 dwarf companion at 6.3 arcmin (~9000 au) from HIP 70849, a K7V star which hosts a 9 Jupiter mass planet with an eccentric orbit. We also report two new stellar M dwarf companions to one G and one metal-rich K star. We infer stellar and substellar binary frequencies for our complete sample of 37 targets of 5.4±3.8% and 2.7±2.7% (1σ confidence level), respectively, for projected physical separations larger than ~60-160 au assuming the range of distances of planet-host stars (24-75 pc). These values are comparable to the frequencies of non planet-host stars. We find that the period-eccentricity trend holds with a lack of multiple systems with planets at large eccentricities (e> 0.2) for periods less than 40 days. However, the lack of planets more massive than 2.5 Jupiter masses and short periods (<40 days) orbiting single stars is not so obvious due to recent discoveries by ground-based transit surveys and space missions. Appendix A is available in electronic form at http://www.aanda.orgSpectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/569/A120Based on observations collected at the European Organisation for Astronomical Research

  14. UV-frequency metrology on CO (a{sup 3}{Pi}): Isotope effects and sensitivity to a variation of the proton-to-electron mass ratio

    SciTech Connect

    Nijs, Adrian J. de; Salumbides, Edcel J.; Eikema, Kjeld S. E.; Ubachs, Wim; Bethlem, Hendrick L.

    2011-11-15

    UV-frequency metrology has been performed on the a{sup 3}{Pi} - X{sup 1}{Sigma}{sup +} (0,0) band of various isotopologues of CO using a frequency-quadrupled injection-seeded narrow-band pulsed titanium:sapphire laser referenced to a frequency comb laser. The band origin is determined with an accuracy of 5 MHz ({delta}{nu}/{nu}=3x10{sup -9}), while the energy differences between rotational levels in the a{sup 3}{Pi} state are determined with an accuracy of 500 kHz. From these measurements, in combination with previously published radio-frequency and microwave data, a set of molecular constants is obtained that describes the level structure of the a{sup 3}{Pi} state of {sup 12}C{sup 16}O and {sup 13}C{sup 16}O with improved accuracy. Transitions in the different isotopologues are well reproduced by scaling the molecular constants of {sup 12}C{sup 16}O via the common mass-scaling rules. Only the value of the band origin could not be scaled, indicative of a breakdown of the Born-Oppenheimer approximation. Our analysis confirms the extreme sensitivity of two-photon microwave transitions between nearly degenerate rotational levels of different {Omega} manifolds for probing a possible variation of the proton-to-electron mass ratio, {mu}=m{sub p}/m{sub e}, on a laboratory time scale.

  15. Low-frequency variations in surface atmospheric humidity, temperature, and precipitation: Inferences from reanalyses and monthly gridded observational data sets

    NASA Astrophysics Data System (ADS)

    Simmons, A. J.; Willett, K. M.; Jones, P. D.; Thorne, P. W.; Dee, D. P.

    2010-01-01

    Evidence is presented of a reduction in relative humidity over low-latitude and midlatitude land areas over a period of about 10 years leading up to 2008, based on monthly anomalies in surface air temperature and humidity from comprehensive European Centre for Medium-Range Weather Forecasts reanalyses (ERA-40 and ERA-Interim) and from Climatic Research Unit and Hadley Centre analyses of monthly station temperature data (CRUTEM3) and synoptic humidity observations (HadCRUH). The data sets agree well for both temperature and humidity variations for periods and places of overlap, although the average warming over land is larger for the fully sampled ERA data than for the spatially and temporally incomplete CRUTEM3 data. Near-surface specific humidity varies similarly over land and sea, suggesting that the recent reduction in relative humidity over land may be due to limited moisture supply from the oceans, where evaporation has been limited by sea surface temperatures that have not risen in concert with temperatures over land. Continental precipitation from the reanalyses is compared with a new gauge-based Global Precipitation Climatology Centre (GPCC) data set, with the combined gauge and satellite products of the Global Precipitation Climatology Project (GPCP) and the Climate Prediction Center (CPC), Merged Analysis of Precipitation (CMAP), and with CPC's independent gauge analysis of precipitation over land (PREC/L). The reanalyses agree best with the new GPCC and latest GPCP data sets, with ERA-Interim significantly better than ERA-40 at capturing monthly variability. Shifts over time in the differences among the precipitation data sets make it difficult to assess their longer-term variations and any link with longer-term variations in humidity.

  16. Highly-efficient charge separation and polaron delocalization in polymer-fullerene bulk-heterojunctions: a comparative multi-frequency EPR and DFT study.

    PubMed

    Niklas, Jens; Mardis, Kristy L; Banks, Brian P; Grooms, Gregory M; Sperlich, Andreas; Dyakonov, Vladimir; Beaupré, Serge; Leclerc, Mario; Xu, Tao; Yu, Luping; Poluektov, Oleg G

    2013-06-28

    The ongoing depletion of fossil fuels has led to an intensive search for additional renewable energy sources. Solar-based technologies could provide sufficient energy to satisfy the global economic demands in the near future. Photovoltaic (PV) cells are the most promising man-made devices for direct solar energy utilization. Understanding the charge separation and charge transport in PV materials at a molecular level is crucial for improving the efficiency of the solar cells. Here, we use light-induced EPR spectroscopy combined with DFT calculations to study the electronic structure of charge separated states in blends of polymers (P3HT, PCDTBT, and PTB7) and fullerene derivatives (C60-PCBM and C70-PCBM). Solar cells made with the same composites as active layers show power conversion efficiencies of 3.3% (P3HT), 6.1% (PCDTBT), and 7.3% (PTB7), respectively. Upon illumination of these composites, two paramagnetic species are formed due to photo-induced electron transfer between the conjugated polymer and the fullerene. They are the positive, P(+), and negative, P(-), polarons on the polymer backbone and fullerene cage, respectively, and correspond to radical cations and radical anions. Using the high spectral resolution of high-frequency EPR (130 GHz), the EPR spectra of these species were resolved and principal components of the g-tensors were assigned. Light-induced pulsed ENDOR spectroscopy allowed the determination of (1)H hyperfine coupling constants of photogenerated positive and negative polarons. The experimental results obtained for the different polymer-fullerene composites have been compared with DFT calculations, revealing that in all three systems the positive polaron is distributed over distances of 40-60 Å on the polymer chain. This corresponds to about 15 thiophene units for P3HT, approximately three units for PCDTBT, and about three to four units for PTB7. No spin density delocalization between neighboring fullerene molecules was detected by EPR

  17. Highly-Efficient Charge Separation and Polaron Delocalization in Polymer-Fullerene Bulk-Heterojunctions: A Comparative Multi-Frequency EPR & DFT Study

    PubMed Central

    Niklas, Jens; Mardis, Kristy L.; Banks, Brian P.; Grooms, Gregory M.; Sperlich, Andreas; Dyakonov, Vladimir; Beaupré, Serge; Leclerc, Mario; Xu, Tao; Yu, Luping; Poluektov, Oleg G.

    2016-01-01

    The ongoing depletion of fossil fuels has led to an intensive search for additional renewable energy sources. Solar-based technologies could provide sufficient energy to satisfy the global economic demands in the near future. Photovoltaic (PV) cells are the most promising man-made devices for direct solar energy utilization. Understanding the charge separation and charge transport in PV materials at a molecular level is crucial for improving the efficiency of the solar cells. Here, we use light-induced EPR spectroscopy combined with DFT calculations to study the electronic structure of charge separated states in blends of polymers (P3HT, PCDTBT, and PTB7) and fullerene derivatives (C60-PCBM and C70-PCBM). Solar cells made with the same composites as active layers show power conversion efficiencies of 3.3% (P3HT), 6.1% (PCDTBT), and 7.3% (PTB7), respectively. Under illumination of these composites, two paramagnetic species are formed due to photo-induced electron transfer between the conjugated polymer and the fullerene. They are the positive, P+, and negative, P-, polarons on the polymer backbone and fullerene cage, respectively, and correspond to radical cations and radical anions. Using the high spectral resolution of high-frequency EPR (130 GHz), the EPR spectra of these species were resolved and principal components of the g-tensors were assigned. Light-induced pulsed ENDOR spectroscopy allowed the determination of 1H hyperfine coupling constants of photogenerated positive and negative polarons. The experimental results obtained for the different polymer-fullerene composites have been compared with DFT calculations, revealing that in all three systems the positive polaron is distributed over distances of 40 - 60 Å on the polymer chain. This corresponds to about 15 thiophene units for P3HT, approximately three units PCDTBT, and about three to four units for PTB7. No spin density delocalization between neighboring fullerene molecules was detected by EPR. Strong

  18. Variation in Tomato spotted wilt virus titer in Frankliniella occidentalis and its association with frequency of transmission.

    PubMed

    Rotenberg, Dorith; Krishna Kumar, Nallur K; Ullman, Diane E; Montero-Astúa, Mauricio; Willis, David K; German, Thomas L; Whitfield, Anna E

    2009-04-01

    Tomato spotted wilt virus (TSWV) is transmitted in a persistent propagative manner by Frankliniella occidentalis, the western flower thrips. While it is well established that vector competence depends on TSWV acquisition by young larvae and virus replication within the insect, the biological factors associated with frequency of transmission have not been well characterized. We hypothesized that the number of transmission events by a single adult thrips is determined, in part, by the amount of virus harbored (titer) by the insect. Transmission time-course experiments were conducted using a leaf disk assay to determine the efficiency and frequency of TSWV transmission following 2-day inoculation access periods (IAPs). Virus titer in individual adult thrips was determined by real-time quantitative reverse transcriptase-PCR (qRT-PCR) at the end of the experiments. On average, 59% of adults transmitted the virus during the first IAP (2 to 3 days post adult-eclosion). Male thrips were more efficient at transmitting TSWV multiple times compared with female thrips of the same cohort. However, females harbored two to three times more copies of TSWV-N RNA per insect, indicating that factors other than absolute virus titer in the insect contribute to a successful transmission event. Examination of virus titer in individual insects at the end of the third IAP (7 days post adult-eclosion) revealed significant and consistent positive associations between frequency of transmission and virus titer. Our data support the hypothesis that a viruliferous thrips is more likely to transmit multiple times if it harbors a high titer of virus. This quantitative relationship provides new insights into the biological parameters that may influence the spread of TSWV by thrips. PMID:19271982

  19. Low-frequency Intensity Variation of the South Asian High and its relationship to Boreal Summer Intraseasonal Oscillation

    NASA Astrophysics Data System (ADS)

    Shang, Wei; Ren, Xuejuan

    2016-04-01

    The South Asian High (SAH) is an important member among the Asian summer monsoon circulations in the upper troposphere located over the Tibean Plateau and its surrounding areas during boreal summer. This research attempts to study the characteristics and mechanisms of low-frequency oscillation of SAH, using daily ERA-Interim reanalysis dataset and NECP/NCAR OLR data. The empirical orthogonal function (EOF)analysis is performed on 200hPa geopotential height low-frequency anomalies over the 20°-35°N, 35°-110°E for June, July and August from 1979 to 2013. The first EOF mode shows a monopole pattern capturing the strengthening or weakening of the SAH's body. The power spectrum analysis of the corresponding principal component (PC1) time series shows that the first mode has a period about 10-30 days. Positive anomalies appear in the 200hPa geopotential height and negative anomalies appear in their north side when SAH is in positive low-frequency phase. A band with negative outgoing longwave radiation (OLR) anomalies presents from the Arabian Sea, north of Indian Peninsula to Southeast China and Japan Island. Correspondingly, positive anomalous rainfall are contiguous in the north of Indian Peninsula, south of Tibetan Plateau, Southeast China and Japan Island. The lead-lag regression analysis demonstrates that from day -12 to day 0, negative OLR anomalies band move northward and northwest from the equatorial Indian Ocean, the Bay of Bengals, the South China sea and Western North Pacific to the Arabian Sea, north of Indian Peninsula, south of Tibetan Plateau, Southeast China and Japan Island. Corresponding to OLR anomalies, positive rainfall anomalies band have the similar evolution. The spatial pattern of anomalies in integrated apparent heat source and integrated apparent moisture sink resemble that of rainfall and OLR, which correspond more anomalous condensation heat release. The lead-lag regression analysis also shows that the OLR band moving northward

  20. Seasonal, annual and geographic variation in color morph frequencies of the cricket frog, Acris crepitans, in Illinois

    SciTech Connect

    Gray, R.H.

    1983-01-01

    A three-year field study was conducted in Illinois to investigate seasonal, annual and geographic variation in color morph proportions of the cricket frog, Acris crepitans. Life history information (i.e., time of overwintering, emergence of adults in spring, breeding, metamorphosis, emergence of juveniles in summer, and growth and survival) for A. crepitans color morphs was compared to evaluate the potential adaptive significance of this polymorphism. Although seasonal variations in color morph proportions were not significant, some annual and geographic differences were. No differences were found among morphs related to the timing of various life history events. Studies of individual movements, dispersal, growth and survivorship also revealed no differences among morphs. Comparison of these data, as well as physiological and behavioral data for A. crepitans from Illinois, with similar data from Texas and elsewhere suggests that different factors must operate throughout the species range to maintain this color polymorphism. Chance may be a major factor in determining color morph proportions in localized populations in Illinois. 22 references, 5 figures, 3 tables.

  1. Microsatellite frequencies vary with body mass and body temperature in mammals, suggesting correlated variation in mutation rate

    PubMed Central

    Filipe, Laura N.S.

    2014-01-01

    Substitution rate is often found to correlate with life history traits such as body mass, a predictor of population size and longevity, and body temperature. The underlying mechanism is unclear but most models invoke either natural selection or factors such as generation length that change the number of mutation opportunities per unit time. Here we use published genome sequences from 69 mammals to ask whether life history traits impact another form of genetic mutation, the high rates of predominantly neutral slippage in microsatellites. We find that the length-frequency distributions of three common dinucleotide motifs differ greatly between even closely related species. These frequency differences correlate with body mass and body temperature and can be used to predict the phenotype of an unknown species. Importantly, different length microsatellites show complicated patterns of excess and deficit that cannot be explained by a simple model where species with short generation lengths have experienced more mutations. Instead, the patterns probably require changes in mutation rate that impact alleles of different length to different extents. Body temperature plausibly influences mutation rate by modulating the propensity for slippage. Existing hypotheses struggle to account for a link between body mass and mutation rate. However, body mass correlates inversely with population size, which in turn predicts heterozygosity. We suggest that heterozygote instability, HI, the idea that heterozygous sites show increased mutability, could provide a plausible link between body mass and mutation rate. PMID:25392761

  2. Assessing variation in skeletal production from surface death assemblages on the basis of age-frequency distributions

    NASA Astrophysics Data System (ADS)

    Tomasovych, Adam; Kidwell, Susan M.; Foygel Barber, Rina

    2015-04-01

    Age-frequency distributions of dead skeletal material that capture information on the elapsed time since death of individuals on the landscape or seabed provide decadal- to millennial-scale windows into the history of production and on the processes that lead to skeletal disintegration and burial. However, models quantifying the dynamics of skeletal loss assumed that skeletal production has been constant during accumulation of death assemblages. Here, we assess the joint effects of temporally-variable production and skeletal loss on the shape of postmortem age-frequency distributions. We show that the modes of such distributions will tend to be shifted to younger age cohorts relative to the true timing of past production pulses. This shift in the timing of a past production will be higher where loss rates are high and/or the rate of decline in production is slow. We apply the models combining the dynamic of loss and production to death assemblages with the deposit-feeding bivalve Nuculana taphria from the Southern California continental shelf, finding that (1) an onshore-offshore gradient in time averaging is dominated by a gradient in the timing of production, corresponding to the tracking of shallow-water habitats under a sea-level rise, and (2) model estimates of the timing of past production are in good agreement with an independent sea-level curve.

  3. Variation in Meiotic Recombination Frequencies Between Allelic Transgenes Inserted at Different Sites in the Drosophila melanogaster Genome

    PubMed Central

    McMahan, Susan; Kohl, Kathryn P.; Sekelsky, Jeff

    2013-01-01

    Meiotic crossovers are distributed nonrandomly across the genome. Classic studies in Drosophila suggest that the position of a gene along a chromosome arm can affect the outcome of the recombination process, with proximity to the centromere being associated with lower crossing over. To examine this phenomenon molecularly, we developed an assay that measures meiotic crossovers and noncrossover gene conversions between allelic transgenes inserted into different genomic positions. To facilitate collecting a large number of virgin females, we developed a useful genetic system that kills males and undesired classes of females. We found that the recombination frequency at a site in the middle of the X chromosome, where crossovers are normally frequent, was similar to the frequency at the centromere-proximal end of the euchromatin, where crossovers are normally infrequent. In contrast, we recovered no recombinants—crossovers or noncrossovers—at a site on chromosome 4 and at a site toward the distal end of the X chromosome. These results suggest that local sequence or chromatin features have a stronger impact on recombination rates in this transgene assay than position along the chromosome arm. PMID:23797104

  4. Microsatellite frequencies vary with body mass and body temperature in mammals, suggesting correlated variation in mutation rate.

    PubMed

    Amos, William; Filipe, Laura N S

    2014-01-01

    Substitution rate is often found to correlate with life history traits such as body mass, a predictor of population size and longevity, and body temperature. The underlying mechanism is unclear but most models invoke either natural selection or factors such as generation length that change the number of mutation opportunities per unit time. Here we use published genome sequences from 69 mammals to ask whether life history traits impact another form of genetic mutation, the high rates of predominantly neutral slippage in microsatellites. We find that the length-frequency distributions of three common dinucleotide motifs differ greatly between even closely related species. These frequency differences correlate with body mass and body temperature and can be used to predict the phenotype of an unknown species. Importantly, different length microsatellites show complicated patterns of excess and deficit that cannot be explained by a simple model where species with short generation lengths have experienced more mutations. Instead, the patterns probably require changes in mutation rate that impact alleles of different length to different extents. Body temperature plausibly influences mutation rate by modulating the propensity for slippage. Existing hypotheses struggle to account for a link between body mass and mutation rate. However, body mass correlates inversely with population size, which in turn predicts heterozygosity. We suggest that heterozygote instability, HI, the idea that heterozygous sites show increased mutability, could provide a plausible link between body mass and mutation rate. PMID:25392761

  5. Variation of Dielectric and Electrical Properties of Zr-Substituted Lead Calcium Iron Niobate with Temperature and Frequency

    NASA Astrophysics Data System (ADS)

    Puri, Maalti; Bahel, Shalini; Narang, Sukhleen Bindra

    2016-10-01

    The purpose of the present study is to improve the dielectric properties of lead calcium iron niobate with Zr substitution, and to make it suitable for multilayer capacitor applications in resonant circuits. (Pb0.45Ca0.55)(Fe0.5Nb0.5)1- y Zr y O3 dielectric ceramics where y varies from 0.00 to 0.15 in steps of 0.03, that have been synthesized by the columbite precursor method. Dielectric and electrical properties were measured as a function of frequency (10 kHz to 1 MHz) and temperature. Two frequency dependent anomalies were observed in relative permittivity ( ɛ r) versus temperature ( T) plots around 375 K and between 500 K and 575 K. The temperature coefficient of relative permittivity, ( τ ɛ ) has been improved with the substitution of (Fe0.5Nb0.5)4+ ions by Zr4+ ions at B-sites. The single semicircle, observed in Nyquist plots at different temperatures, suggests a single relaxation process in the synthesized samples. The activation energies obtained from different dependences are found to be approximately comparable.

  6. Yearly variations in runoff and frequency of dry years for the conterminous United States, 1911-79

    USGS Publications Warehouse

    Langbein, W.B.; Slack, J.R.

    1982-01-01

    Gaging-station data are presented on variations in annual runoff over the conterminous United States and nearby Canada during the period 1911-79 in tabular and graphic (map) form. These data bring up-to-date and extend backward in time previous reports on streamflow stations by Harbeck and Langbein in 1949 which covered the period 1921-45 and that by Busby in 1963 which covered the period 1931-60. As depicted in Langbein and Slack (1980), these data show that, contained within a rather large seemingly random or sporadic pattern, there appears to be a previously unnoticed degree of similarity in the occurrence of subnormal flows across the country. In each of three regions, viz., West, Center, and East, dry years were concentrated in two sequences, one centered in the 1930 's and the second in the decade from the mid-50 's to the mid-60's. (USGS)

  7. Determination of natural frequencies by coupled method of homotopy perturbation and variational method for strongly nonlinear oscillators

    SciTech Connect

    Akbarzade, M.; Langari, J.

    2011-02-15

    In this paper a new approach combining the features of the homotopy concept with variational approach is proposed to find accurate analytical solutions for nonlinear oscillators with and without a fractional power restoring force. Since the first-order approximation leads to very accurate results, comparisons with other results are presented to show the effectiveness of this method. The validity of the method is independent of whether or not there exist small or large parameters in the considered nonlinear equations; the obtained results prove the validity and efficiency of the method, which can be easily extended to other strongly nonlinear problems. At the end we compare our procedure with the optimal homotopy perturbation method.

  8. Variation in Holocene El Niño frequencies: Climate records and cultural consequences in ancient Peru

    NASA Astrophysics Data System (ADS)

    Sandweiss, Daniel H.; Maasch, Kirk A.; Burger, Richard L.; Richardson, James B., III; Rollins, Harold B.; Clement, Amy

    2001-07-01

    Analysis of mollusks from archaeological sites on the north and central coasts of Peru indicates that between ca. 5800 and 3200 2800 cal yr B.P., El Niño events were less frequent than today, with modern, rapid recurrence intervals achieved only after that time. For several millennia prior to 5.8 ka, El Niño events had been absent or very different from today. The phenomena called El Niño have had severe consequences for the modern and colonial (historically recorded) inhabitants of Peru, and El Niño events also influenced prehistoric cultural development: the onset of El Niño events at 5.8 ka correlates temporally with the beginning of monumental temple construction on the Peruvian coast, and the increase in El Niño frequency after 3.2 2.8 ka correlates with the abandonment of monumental temples in the same region.

  9. Using recent high-frequency surveys to reconstitute 35 years of organic carbon variations in a eutrophic lowland river.

    PubMed

    Minaudo, C; Moatar, F; Coynel, A; Etcheber, H; Gassama, N; Curie, F

    2016-01-01

    Concentrations of dissolved and particulate organic carbon (DOC and POC), total suspended solids (TSS), were measured daily, and phytoplankton pigments (chlorophyll-a and pheopigments) were measured every 3 days at three strategic stations along the eutrophic Loire River between November 2011 and November 2013 marked by a high annual and seasonal variability in hydrological regimes. This unique high-frequency dataset allowed to determine the POC origin (autochthonous or allochthonous). Some strong relationships were evidenced between POC, total pigments and TSS and were tested on a long-term database with a lower frequency (monthly data) to reconstitute unmeasured algal and detrital POC concentrations and estimate annual total organic carbon (TOC) fluxes from 1980 onwards. The results were subjected to only ≈25 % uncertainty and showed that the annual TOC fluxes at the outlet of the Loire River decreased from 520 10(3) tC year(-1) (i.e. 4.7 t km(-2) year(-1)) in the early 1990s to 150 10(3) tC year(-1) (i.e. 1.4 t km(-2) year(-1)) in 2012. Although DOC always dominates, the autochthonous POC represented 35 % of the TOC load at the basin outlet by the end of the 1980s and declined to finally represent 15 % only of the TOC. The control of phosphorus direct inputs and the invasion by Corbicula clams spp. which both occurred since the early 1990s probably highly reduced the development of phytoplankton. Consequently, the autochthonous POC contribution declined and TSS concentrations in summertime significantly decreased as well as a result of both less phytoplankton and less calcite precipitation. At the present time, at least 75 % of the POC has allochthonous origins in the upper Middle Loire but downstream, autochthonous POC dominates during summer phytoplanktonic blooms when total pigments concentrations reach up to 70 μg L(-1) (equivalent to 75 % of the total POC).

  10. Body size variation of four latitudinally-separated populations of a toad species: age and growth rate as the proximate determinants.

    PubMed

    Yu, Tonglei; Lu, Xin

    2013-09-01

    Age and growth rate are critical parameters determining the body size of adult anurans, which grow indeterminately. Therefore, evaluating their relative importance and selective pressures acting on them may help to explain variation in body size of anurans across geographical populations. Based on the data on body size and skeletochronological age of 4 Asiatic toad (Bufo gargarizans) populations that are widely separated in latitude, the present study showed that toads at the northern extremity of the range were the oldest, on average, and grew relatively fast, toads at the southern end of the range were relatively old but grew fastest, whereas mid-latitude toads were intermediate in both traits. These results indicated that relative contributions of age and growth rate to body size differed among populations. From a life history perspective, greater age attained by toads at higher latitudes should result from delayed maturation, and faster growth from an adaptive response to strong seasonal time constraints; in contrast, selective pressures on the 2 parameters at lower latitudes might be associated, respectively, with low adult death rates and longer favorable growing seasons.

  11. Estimating KIR Haplotype Frequencies on a Cohort of 10,000 Individuals: A Comprehensive Study on Population Variations, Typing Resolutions, and Reference Haplotypes

    PubMed Central

    Jayaraman, Jyothi; Trowsdale, John; Traherne, James; Kuang, Rui; Spellman, Stephen; Maiers, Martin

    2016-01-01

    The killer cell immunoglobulin-like receptors (KIR) mediate human natural killer (NK) cell cytotoxicity via activating or inhibiting signals. Although informative and functional haplotype patterns have been reported, most genotyping has been performed at resolutions that are structurally ambiguous. In order to leverage structural information given low-resolution genotypes, we performed experiments to quantify the effects of population variations, reference haplotypes, and genotyping resolutions on population-level haplotype frequency estimations as well as predictions of individual haplotypes. We genotyped 10,157 unrelated individuals in 5 populations (518 African American[AFA], 258 Asian or Pacific Islander[API], 8,245 European[EUR], 1,073 Hispanic[HIS], and 63 Native American[NAM]) for KIR gene presence/absence (PA), and additionally half of the AFA samples for KIR gene copy number variation (CNV). A custom EM algorithm was used to estimate haplotype frequencies for each population by interpretation in the context of three sets of reference haplotypes. The algorithm also assigns each individual the haplotype pairs of maximum likelihood. Generally, our haplotype frequency estimates agree with similar previous publications to within <5% difference for all haplotypes. The exception is that estimates for NAM from the U.S. showed higher frequency association of cB02 with tA01 (+14%) instead of tB01 (-8.5%) compared to a previous study of NAM from south of the U.S. The higher-resolution CNV genotyping on the AFA samples allowed unambiguous haplotype-pair assignments for the majority of individuals, resulting in a 22% higher median typing resolution score (TRS), which measures likelihood of self-match in the context of population-specific haplo- and geno-types. The use of TRS to quantify reduced ambiguity with CNV data clearly revealed the few individuals with ambiguous genotypes as outliers. It is observed that typing resolution and reference haplotype set influence

  12. Parametric variation of gamma frequency and power with luminance contrast: A comparative study of human MEG and monkey LFP and spike responses.

    PubMed

    Hadjipapas, A; Lowet, E; Roberts, M J; Peter, A; De Weerd, P

    2015-05-15

    Gamma oscillations contribute significantly to the manner in which neural activity is bound into functional assemblies. The mechanisms that underlie the human gamma response, however, are poorly understood. Previous computational models of gamma rely heavily on the results of invasive recordings in animals, and it is difficult to assess whether these models hold in humans. Computational models of gamma predict specific changes in gamma spectral response with increased excitatory drive. Hence, differences and commonalities between spikes, LFPs and MEG in the spectral responses to changes in excitatory drive can lead to a refinement of existing gamma models. We compared gamma spectral responses to varying contrasts in a monkey dataset acquired previously (Roberts et al., 2013) with spectral responses to similar contrast variations in a new human MEG dataset. We found parametric frequency shifts with increasing contrast in human MEG at the single-subject and the single-trial level, analogous to those observed in the monkey. Additionally, we observed parametric modulations of spectral asymmetry, consistent across spikes, LFP and MEG. However, while gamma power scaled linearly with contrast in MEG, it saturated at high contrasts in both the LFP and spiking data. Thus, while gamma frequency changes to varying contrasts were comparable across spikes, LFP and MEG, gamma power changes were not. This indicates that gamma frequency may be a more stable parameter across scales of measurements and species than gamma power. The comparative approach undertaken here represents a fruitful path towards a better understanding of gamma oscillations in the human brain.

  13. Assessment of periodic sub-diurnal Earth rotation variations at tidal frequencies through transformation of VLBI normal equation systems

    NASA Astrophysics Data System (ADS)

    Artz, Thomas; Tesmer Née Böckmann, Sarah; Nothnagel, Axel

    2011-09-01

    We present an empirical model for periodic variations of diurnal and sub-diurnal Earth rotation parameters (ERPs) that was derived based on the transformation of normal equation (NEQ) systems of Very Long Baseline Interferometry (VLBI) observing sessions. NEQ systems that contain highly resolved polar motion and UT1-TAI with a temporal resolution of 15 min were generated and then transformed to the coefficients of the tidal ERP model to be solved for. To investigate the quality of this model, comparisons with empirical models from the Global Positioning System (GPS), another VLBI model and the model adopted by the conventions of the International Earth Rotation and Reference Systems Service (IERS) were performed. The absolute coefficients of these models agree almost completely within 7.5 μ as in polar motion and 0.5 μ s in UT1-TAI. Several bigger differences exist, which are discussed in this paper. To be able to compare the model estimates with results of the continuous VLBI campaigns, where signals with periods of 8 and 6 h were detected, terms in the ter- and quarter-diurnal band were included in the tidal ERP model. Unfortunately, almost no common features with the results of continuous VLBI campaigns or ERP predictions in these tidal bands can be seen.

  14. Higher frequency of social learning in China than in the West shows cultural variation in the dynamics of cultural evolution

    PubMed Central

    Mesoudi, Alex; Chang, Lei; Murray, Keelin; Lu, Hui Jing

    2015-01-01

    Cultural evolutionary models have identified a range of conditions under which social learning (copying others) is predicted to be adaptive relative to asocial learning (learning on one's own), particularly in humans where socially learned information can accumulate over successive generations. However, cultural evolution and behavioural economics experiments have consistently shown apparently maladaptive under-utilization of social information in Western populations. Here we provide experimental evidence of cultural variation in people's use of social learning, potentially explaining this mismatch. People in mainland China showed significantly more social learning than British people in an artefact-design task designed to assess the adaptiveness of social information use. People in Hong Kong, and Chinese immigrants in the UK, resembled British people in their social information use, suggesting a recent shift in these groups from social to asocial learning due to exposure to Western culture. Finally, Chinese mainland participants responded less than other participants to increased environmental change within the task. Our results suggest that learning strategies in humans are culturally variable and not genetically fixed, necessitating the study of the ‘social learning of social learning strategies' whereby the dynamics of cultural evolution are responsive to social processes, such as migration, education and globalization. PMID:25392473

  15. Higher frequency of social learning in China than in the West shows cultural variation in the dynamics of cultural evolution.

    PubMed

    Mesoudi, Alex; Chang, Lei; Murray, Keelin; Lu, Hui Jing

    2015-01-01

    Cultural evolutionary models have identified a range of conditions under which social learning (copying others) is predicted to be adaptive relative to asocial learning (learning on one's own), particularly in humans where socially learned information can accumulate over successive generations. However, cultural evolution and behavioural economics experiments have consistently shown apparently maladaptive under-utilization of social information in Western populations. Here we provide experimental evidence of cultural variation in people's use of social learning, potentially explaining this mismatch. People in mainland China showed significantly more social learning than British people in an artefact-design task designed to assess the adaptiveness of social information use. People in Hong Kong, and Chinese immigrants in the UK, resembled British people in their social information use, suggesting a recent shift in these groups from social to asocial learning due to exposure to Western culture. Finally, Chinese mainland participants responded less than other participants to increased environmental change within the task. Our results suggest that learning strategies in humans are culturally variable and not genetically fixed, necessitating the study of the 'social learning of social learning strategies' whereby the dynamics of cultural evolution are responsive to social processes, such as migration, education and globalization.

  16. Free-Ranging Male Koalas Use Size-Related Variation in Formant Frequencies to Assess Rival Males

    PubMed Central

    Charlton, Benjamin D.; Whisson, Desley A.; Reby, David

    2013-01-01

    Although the use of formant frequencies in nonhuman animal vocal communication systems has received considerable recent interest, only a few studies have examined the importance of these acoustic cues to body size during intra-sexual competition between males. Here we used playback experiments to present free-ranging male koalas with re-synthesised bellow vocalisations in which the formants were shifted to simulate either a large or a small adult male. We found that male looking responses did not differ according to the size variant condition played back. In contrast, male koalas produced longer bellows and spent more time bellowing when they were presented with playbacks simulating larger rivals. In addition, males were significantly slower to respond to this class of playback stimuli than they were to bellows simulating small males. Our results indicate that male koalas invest more effort into their vocal responses when they are presented with bellows that have lower formants indicative of larger rivals, but also show that males are slower to engage in vocal exchanges with larger males that represent more dangerous rivals. By demonstrating that male koalas use formants to assess rivals during the breeding season we have provided evidence that male-male competition constitutes an important selection pressure for broadcasting and attending to size-related formant information in this species. Further empirical studies should investigate the extent to which the use of formants during intra-sexual competition is widespread throughout mammals. PMID:23922967

  17. High frequency (hourly) variation in vertical distribution and abundance of meroplanktonic larvae in nearshore waters during strong internal tidal forcing

    NASA Astrophysics Data System (ADS)

    Liévana MacTavish, A.; Ladah, L. B.; Lavín, M. F.; Filonov, A.; Tapia, Fabian J.; Leichter, J.

    2016-04-01

    We related the vertical distribution and abundance of nearshore meroplankton at hourly time scales with internal tidal wave events. We proposed that significant changes in plankter abundance would occur across internal tidal fronts, and that surface and bottom strata would respond in opposite fashions. First-mode internal tidal bores propagating in the alongshore direction were detected in water-column currents and baroclinic temperature changes. Surface and bottom currents always flowed in opposite directions, and abrupt flow reversals coincided with large temperature changes during arrival of bores. Crab zoeae and barnacle cyprids were more abundant in the bottom strata, whereas barnacle nauplii showed the opposite pattern. Significant changes in vertical distribution and abundance of target meroplankters occurred across internal tidal fronts, especially for crabs at depth, with surface and bottom organisms responding in opposite fashions. Changes in plankter abundance were significantly correlated with current flows in the strata where they were most abundant. The manner in which plankters were affected (increasing or decreasing abundance) appeared to be modulated by their vertical position within the water column. The significant differences found at the high frequencies of this study, maintained across sampling days, suggest that nearshore meroplankton populations may have greater and more consistent temporal and vertical variability than previously considered.

  18. Spatial variations in the frequency-magnitude distribution of earthquakes at Soufriere Hills Volcano, Montserrat, West Indies

    USGS Publications Warehouse

    Power, J.A.; Wyss, M.; Latchman, J.L.

    1998-01-01

    The frequency-magnitude distribution of earthquakes measured by the b-value is determined as a function of space beneath Soufriere Hills Volcano, Montserrat, from data recorded between August 1, 1995 and March 31, 1996. A volume of anomalously high b-values (b > 3.0) with a 1.5 km radius is imaged at depths of 0 and 1.5 km beneath English's Crater and Chance's Peak. This high b-value anomaly extends southwest to Gage's Soufriere. At depths greater than 2.5 km volumes of comparatively low b-values (b-1) are found beneath St. George's Hill, Windy Hill, and below 2.5 km depth and to the south of English's Crater. We speculate the depth of high b-value anomalies under volcanoes may be a function of silica content, modified by some additional factors, with the most siliceous having these volumes that are highly fractured or contain high pore pressure at the shallowest depths. Copyright 1998 by the American Geophysical Union.

  19. Product separator

    DOEpatents

    Welsh, Robert A.; Deurbrouck, Albert W.

    1976-01-20

    A secondary light sensitive photoelectric product separator for use with a primary product separator that concentrates a material so that it is visually distinguishable from adjacent materials. The concentrate separation is accomplished first by feeding the material onto a vibratory inclined surface with a liquid flow, such as a wet concentrating table. Vibrations generally perpendicular to the stream direction of flow cause the concentrate to separate from its mixture according to its color. When the concentrate and its surrounding stream reach the recovery end of the table, a detecting device notes the line of color demarcation and triggers a signal if it differs from a normal condition. If no difference is noted nothing moves on the second separator. However, if a difference is detected in the constant monitoring of the color line's location, a product splitter and recovery unit normally positioned near the color line at the recovery end, moves to a new position. In this manner the selected separated concentrate is recovered at a maximum rate regardless of variations in the flow stream or other conditions present.

  20. Seasonal Variations of the James Webb Space Telescope Orbital Dynamics

    NASA Technical Reports Server (NTRS)

    Brown, Jonathan; Peterson, Jeremy; Villac, Benjamin; Yu, Wayne

    2015-01-01

    LV separation state is fixed ECEF, so inertial states vary with hourly, daily, monthly, and yearly frequencies The net effect of all frequencies leads to significant variations in orbit geometry Injection states can be matched with invariant manifolds of periodic orbits in the CR3BP to explain observed final orbit.

  1. Molecular spectrum of somatic EGFR and KRAS gene mutations in non small cell lung carcinoma: determination of frequency, distribution pattern and identification of novel variations in Indian patients.

    PubMed

    Das, Bibhu Ranjan; Bhaumik, Sangeet; Ahmad, Firoz; Mandsaurwala, Aziz; Satam, Heena

    2015-07-01

    Somatic mutations of EGFR and KRAS gene represent the most common alterations currently known in NSCLC patients. This study explored the frequency, distribution pattern of EGFR and KRAS mutations in Indian patients. The frequencies of EGFR and KRAS mutations were 29 % (116/400) and 4.5 % (6/132) respectively. Both EGFR and KRAS mutations were prevalent in females, and a trend towards higher mutation frequency was seen in patients under ≥ 60 years age. The presence of EGFR and KRAS mutations were higher in adenocarcinomas in comparison to other histological subtype. Sequencing analysis of EGFR exon 18 revealed Inframe deletion (G709_T710 > A) and missense mutation (K713R). Among exon 19 positive cases, 49.3 % (37/75) were in-frame deletions, of which E746_A750del was frequent. Similarly, ~47 % (35/75) cases showed complex mutation involving indel. Among mutations in exon 20 (N = 9), 8 were substitutions, one showed duplication, while all exon 21 mutations were of the missense types with L858R as the most recurrent type. Sequencing analysis of KRAS exon 1 revealed three different types codon 12 substitutions resulting in c34G > T (G12C) (n = 4), c.35G > A (G12D) (n = 1), and c.35G > T (G12V) (n = 1). In conclusion, the present study is an example of molecular diversity of EGFR and KRAS gene in Indian patients and further confirms that the frequency of EGFR and KRAS mutations varies considerably globally. To the best of our knowledge, this is the first Indian study to evaluate KRAS mutation. The current study also served to identify novel variations that added new insights into the genetic heterogeneity of NSCLC.

  2. Antigenic topology of the P29 surface lipoprotein of Mycoplasma fermentans: differential display of epitopes results in high-frequency phase variation.

    PubMed

    Theiss, P; Karpas, A; Wise, K S

    1996-05-01

    Antibodies to P29, a major lipid-modified surface protein of Mycoplasma fermentans, reveal phase variation of surface epitopes occurring with high frequency in clonal lineages of the organism. This occurs despite continuous expression of the entire epitope-bearing P29 product (detected by Western immunoblotting) and contrasts with phase variation of other surface antigens mediated by differential expression of proteins. To understand the structure and antigenic topology of P29, the single-copy p29 gene from strain PG18 was cloned and sequenced. The gene encodes a prolipoprotein containing a signal sequence predicted to be modified with lipid and cleaved at the N-terminal Cys-1 residue of the mature P29 lipoprotein. The remaining 218-residue hydrophilic sequence of P29 is predicted to be located external to the single plasma membrane. Additional Cys residues at positions 91 and 128 in the mature protein were shown to form a 36-residue disulfide loop by selectively labeling sulfhydryl groups that were liberated only after chemical reduction of monomeric P29. Two nearly identical charged amino acid sequences occurred in P29, within the disulfide loop and upstream of this structure. Two distinct epitopes binding different monoclonal antibodies were associated with opposite ends of the P29 protein, by mapping products expressed in Escherichia coli from PCR-generated 3' deletion mutations of the p29 gene. Each monoclonal antibody detected high-frequency and noncoordinate changes in accessibility of the corresponding epitopes in colony immunoblots of clonal variants, yet sequencing of the p29 gene from these variants and analysis of disulfide bonds revealed no associated changes in the primary sequence or disulfide loop structure of P29. These results suggest that P29 surface epitope variation may involve masking of selected regions of P29, possibly by other surface components undergoing phase variation by differential expression. Differential masking may be an important

  3. Celiac disease T-cell epitopes from gamma-gliadins: immunoreactivity depends on the genome of origin, transcript frequency, and flanking protein variation

    PubMed Central

    2012-01-01

    Background Celiac disease (CD) is caused by an uncontrolled immune response to gluten, a heterogeneous mixture of wheat storage proteins. The CD-toxicity of these proteins and their derived peptides is depending on the presence of specific T-cell epitopes (9-mer peptides; CD epitopes) that mediate the stimulation of HLA-DQ2/8 restricted T-cells. Next to the thoroughly characterized major T-cell epitopes derived from the α-gliadin fraction of gluten, γ-gliadin peptides are also known to stimulate T-cells of celiac disease patients. To pinpoint CD-toxic γ-gliadins in hexaploid bread wheat, we examined the variation of T-cell epitopes involved in CD in γ-gliadin transcripts of developing bread wheat grains. Results A detailed analysis of the genetic variation present in γ-gliadin transcripts of bread wheat (T. aestivum, allo-hexaploid, carrying the A, B and D genome), together with genomic γ-gliadin sequences from ancestrally related diploid wheat species, enabled the assignment of sequence variants to one of the three genomic γ-gliadin loci, Gli-A1, Gli-B1 or Gli-D1. Almost half of the γ-gliadin transcripts of bread wheat (49%) was assigned to locus Gli-D1. Transcripts from each locus differed in CD epitope content and composition. The Gli-D1 transcripts contained the highest frequency of canonical CD epitope cores (on average 10.1 per transcript) followed by the Gli-A1 transcripts (8.6) and the Gli-B1 transcripts (5.4). The natural variants of the major CD epitope from γ-gliadins, DQ2-γ-I, showed variation in their capacity to induce in vitro proliferation of a DQ2-γ-I specific and HLA-DQ2 restricted T-cell clone. Conclusions Evaluating the CD epitopes derived from γ-gliadins in their natural context of flanking protein variation, genome specificity and transcript frequency is a significant step towards accurate quantification of the CD toxicity of bread wheat. This approach can be used to predict relative levels of CD toxicity of individual wheat

  4. High-Frequency Observation of Water Spectrum and Its Application in Monitoring of Dynamic Variation of Suspended Materials in the Hangzhou Bay.

    PubMed

    Dai, Qian; Pan, De-lu; He, Xian-qiang; Zhu, Qian-kun; Gong, Fang; Huang, Hai-qing

    2015-11-01

    In situ measurement of water spectrum is the basis of the validation of the ocean color remote sensing. The traditional method to obtain the water spectrum is based on the shipboard measurement at limited stations, which is difficult to meet the requirement of validation of ocean color remote sensing in the highly dynamic coastal waters. To overcome this shortage, continuously observing systems of water spectrum have been developed in the world. However, so far, there are still few high-frequency observation systems of the water spectrum in coastal waters, especially in the highly turbid and high-dynamic waters. Here, we established a high-frequency water-spectrum observing system based on tower in the Hangzhou Bay. The system measures the water spectrum at a step of 3 minutes, which can fully match the satellite observation. In this paper, we primarily developed a data processing method for the tower-based high-frequency water spectrum data, to realize automatic judgment of clear sky, sun glint, platform shadow, and weak illumination, etc. , and verified the processing results. The results show that the normalized water-leaving radiance spectra obtained through tower observation have relatively high consistency with the shipboard measurement results, with correlation coefficient of more than 0. 99, and average relative error of 9.96%. In addition, the long-term observation capability of the tower-based high-frequency water-spectrum observing system was evaluated, and the results show that although the system has run for one year, the normalized water-leaving radiance obtained by this system have good consistency with the synchronously measurement by Portable spectrometer ASD in respect of spectral shape and value, with correlation coefficient of more than 0.90 and average relative error of 6.48%. Moreover, the water spectra from high-frequency observation by the system can be used to effectively monitor the rapid dynamic variation in concentration of suspended

  5. High-Frequency Observation of Water Spectrum and Its Application in Monitoring of Dynamic Variation of Suspended Materials in the Hangzhou Bay.

    PubMed

    Dai, Qian; Pan, De-lu; He, Xian-qiang; Zhu, Qian-kun; Gong, Fang; Huang, Hai-qing

    2015-11-01

    In situ measurement of water spectrum is the basis of the validation of the ocean color remote sensing. The traditional method to obtain the water spectrum is based on the shipboard measurement at limited stations, which is difficult to meet the requirement of validation of ocean color remote sensing in the highly dynamic coastal waters. To overcome this shortage, continuously observing systems of water spectrum have been developed in the world. However, so far, there are still few high-frequency observation systems of the water spectrum in coastal waters, especially in the highly turbid and high-dynamic waters. Here, we established a high-frequency water-spectrum observing system based on tower in the Hangzhou Bay. The system measures the water spectrum at a step of 3 minutes, which can fully match the satellite observation. In this paper, we primarily developed a data processing method for the tower-based high-frequency water spectrum data, to realize automatic judgment of clear sky, sun glint, platform shadow, and weak illumination, etc. , and verified the processing results. The results show that the normalized water-leaving radiance spectra obtained through tower observation have relatively high consistency with the shipboard measurement results, with correlation coefficient of more than 0. 99, and average relative error of 9.96%. In addition, the long-term observation capability of the tower-based high-frequency water-spectrum observing system was evaluated, and the results show that although the system has run for one year, the normalized water-leaving radiance obtained by this system have good consistency with the synchronously measurement by Portable spectrometer ASD in respect of spectral shape and value, with correlation coefficient of more than 0.90 and average relative error of 6.48%. Moreover, the water spectra from high-frequency observation by the system can be used to effectively monitor the rapid dynamic variation in concentration of suspended

  6. Modeling the variations of reflection coefficient of Earth's lower ionosphere using very low frequency radio wave data by artificial neural network

    NASA Astrophysics Data System (ADS)

    Ghanbari, Keyvan; Khakian Ghomi, Mehdi; Mohammadi, Mohammad; Marbouti, Marjan; Tan, Le Minh

    2016-08-01

    The ionized atmosphere lying from 50 to 600 km above surface, known as ionosphere, contains high amount of electrons and ions. Very Low Frequency (VLF) radio waves with frequencies between 3 and 30 kHz are reflected from the lower ionosphere specifically D-region. A lot of applications in long range communications and navigation systems have been inspired by this characteristic of ionosphere. There are several factors which affect the ionization rate in this region, such as: time of day (presence of sun in the sky), solar zenith angle (seasons) and solar activities. Due to nonlinear response of ionospheric reflection coefficient to these factors, finding an accurate relation between these parameters and reflection coefficient is an arduous task. In order to model these kinds of nonlinear functionalities, some numerical methods are employed. One of these methods is artificial neural network (ANN). In this paper, the VLF radio wave data of 4 sudden ionospheric disturbance (SID) stations are given to a multi-layer perceptron ANN in order to simulate the variations of reflection coefficient of D region ionosphere. After training, validation and testing the ANN, outputs of ANN and observed values are plotted together for 2 random cases of each station. By evaluating the results using 2 parameters of pearson correlation coefficient and root mean square error, a satisfying agreement was found between ANN outputs and real observed data.

  7. Variations of the critical foE-frequency of the ionosphere connected with earthquakes. Evaluation of observations of the vertical sounding station "Tokyo"

    NASA Astrophysics Data System (ADS)

    Liperovskaya, Elena V.; Meister, Claudia-Veronika; Hoffmann, Dieter H. H.; Silina, Alexandra S.

    2016-04-01

    In the present work the critical frequencies foE and foF2 of the ionosphere are considered as possible earthquake precursors. The statistical analysis of the critical frequencies is carried out based on the data of the vertical sounding station (VSS) "Kokubunji" ("Tokyo") (ϕ = 35.7o N, λ = 139.5o E, 1957-1988) obtained every hour. Disturbances are considered on the background of seasonal, geomagnetic as well as 11-years and 27-days Solar variations. Special normalized parameters E and F are introduced, which represent the almost seasonal-independent parts of foE and foF2. Days with high Solar (Wolf number > 100) and geomagnetic (ΣKp > 25) activities are excluded from the analysis. For all data (observed every hour) analysed, no correlations of the normalized parameters E and F are found. One day before the seismic shock, a positive correlation is observed. The superimposed epochs method is used to determine the temporal behaviour of E and F. It is found that E and F decrease one day before the earthquakes provided that the seismic shocks occur at distances 600 < R < 1000 km from the VSS, and that the focus of earthquakes with magnitudes M > 5.5 is situated at depths smaller than 60 km. The reliability of the effect is larger than 98 %. Possible physical mechanisms of the phenomenon are discussed.

  8. Hg(+) Frequency Standards

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2000-01-01

    In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

  9. Along-strike variations in fault frictional properties along the San Andreas Fault near Cholame, California from joint earthquake and low-frequency earthquake relocations

    USGS Publications Warehouse

    Harrington, R.M; Cochran, Elizabeth S.; Griffiths, E.M.; Zeng, X.; Thurber, C.

    2016-01-01

    Recent observations of low‐frequency earthquakes (LFEs) and tectonic tremor along the Parkfield–Cholame segment of the San Andreas fault suggest slow‐slip earthquakes occur in a transition zone between the shallow fault, which accommodates slip by a combination of aseismic creep and earthquakes (<15  km depth), and the deep fault, which accommodates slip by stable sliding (>35  km depth). However, the spatial relationship between shallow earthquakes and LFEs remains unclear. Here, we present precise relocations of 34 earthquakes and 34 LFEs recorded during a temporary deployment of 13 broadband seismic stations from May 2010 to July 2011. We use the temporary array waveform data, along with data from permanent seismic stations and a new high‐resolution 3D velocity model, to illuminate the fine‐scale details of the seismicity distribution near Cholame and the relation to the distribution of LFEs. The depth of the boundary between earthquakes and LFE hypocenters changes along strike and roughly follows the 350°C isotherm, suggesting frictional behavior may be, in part, thermally controlled. We observe no overlap in the depth of earthquakes and LFEs, with an ∼5  km separation between the deepest earthquakes and shallowest LFEs. In addition, clustering in the relocated seismicity near the 2004 Mw 6.0 Parkfield earthquake hypocenter and near the northern boundary of the 1857 Mw 7.8 Fort Tejon rupture may highlight areas of frictional heterogeneities on the fault where earthquakes tend to nucleate.

  10. Separation of isotopes of carbon upon the multiphoton single-frequency dissociation of chlorodifluoromethane molecules in the presence of hydrogen iodine

    SciTech Connect

    Velichko, A.M.; Nadeikin, A.A.; Nikitin, A.I.; Pimenova, N.V.; Tal'roze, V.L.

    1987-11-01

    Chlorodifluoromethane (CF/sub 2/HCl) is considered to be one of the the promising substances for setting up the industrial process of the laser separation /sup 12/C and /sup 13/C isotopes. The secondary chemical processes accompanying the multiphoton dissociation of chlorodifluoromethane in the presence of hydrogen iodide have been investigated. The values of the separation coefficients of the isotopes of carbon in the products CF/sub 2/HI and CF/sub 2/H/sub 2/ have been obtained.

  11. Cu mesh's super-hydrophobic and oleophobic properties with variations in gravitational pressure and surface components for oil/water separation applications

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Zhang, Qin; Xiao, Haibo; Xu, Jie; Li, Qintao; Pan, Xiaohui; Huang, Zhiyong

    2014-09-01

    The super-hydrophobic and super-oleophilic properties of various materials have been utilized to separate oil from water. These properties induce both oil penetration and water slide off. This research demonstrates that the mesh with both super-hydrophobic and oleophobic properties, with a water contact angle (WCA) higher than 150° and oil contact angle (OCA) near 140°, can also be used to separate oil from. Oil has a higher probability than water of entering into the interstice of the Cu mesh surface and passing through it due to the capillarity effect, van der Waals attractions and the effects of gravitational pressure. The modified mesh surface can easily adsorb the oil, which then forms a film, due to the very strong adhesion properties of the oil molecules. The oil film then contributes to the water sliding off. These properties can be used to separate oil from water with separation efficiencies reaching 99.3%. Additionally, the separation of an oil/water mixture using sand permeated with oil yielded separation efficiencies exceeding 90%.

  12. Kerosene-water separation in T-junction with orientation upward branch with a 60° angle: Variation of diameter ratio

    NASA Astrophysics Data System (ADS)

    Puspitasari, Dewi; Indarto, Purnomo, Khasani

    2016-06-01

    Research on the T-junction is still underway for the flow of liquid-liquid (kerosene-water). Some research on the characteristics of kerosene-water separation was performed using T-junction oriented upward branch with a 60° angle. To observe the effect of diameters ratio on the phase separation that produced T-junction then made a test section with a horizontal pipe diameter 36 mm, while the side arm 36 mm diameter, 26 mm and 19 mm (diameters ratio of 1, 0.7 and 0.5) by using plexiglass pipe type. Based on experimental results and visualization of data flow in the test section, to the value obtained 60% water cut, the maximum separation efficiency of 94%, FK = 0.94 and FW = 0.001 with a diameter ratio of 1. For other diameter ratio of 0.7 and 0.5 respectively separation efficiency of 66%, FK = 1 and Fw = 0.34 for 0.7 and separation efficiency of 84%, FK = 1 and Fw = 0.16 for 0.5, the best value is obtained at a water cut 60% too. All the best conditions to achieve the above-stratified flow pattern.

  13. Separate and Combined Effects of Behavior Rehearsal and Self-Other Modeling Variations on the Grooming Skill Acquisition of Mentally Retarded Women.

    ERIC Educational Resources Information Center

    Petroski, Richard A.; And Others

    1983-01-01

    Compared the separate and combined effects of behavior rehearsal and modeling on grooming skill development of mentally retarded women (N=48). All treatments were superior to the control condition. Modeling and behavior rehearsal were both effective but there was no advantage to combining them. Cost effectiveness favored the other-model procedure.…

  14. Use of a novel cell adhesion method and digital measurement to show stimulus-dependent variation in somatic and oral ciliary beat frequency in Paramecium.

    PubMed

    Bell, Wade E; Hallworth, Richard; Wyatt, Todd A; Sisson, Joseph H

    2015-01-01

    When Paramecium encounters positive stimuli, the membrane hyperpolarizes and ciliary beat frequency increases. We adapted an established immobilization protocol using a biological adhesive and a novel digital analysis system to quantify beat frequency in immobilized Paramecium. Cells showed low mortality and demonstrated beat frequencies consistent with previous studies. Chemoattractant molecules, reduction in external potassium, and posterior stimulation all increased somatic beat frequency. In all cases, the oral groove cilia maintained a higher beat frequency than mid-body cilia, but only oral cilia from cells stimulated with chemoattactants showed an increase from basal levels.

  15. Manifestation of planetary wave-type oscillations in variations in the critical frequencies of the ionospheric F2 layer in the Asian region

    NASA Astrophysics Data System (ADS)

    Vergasova, G. V.; Kazimirovskii, E. S.; Polekh, N. M.; Xiong, J.; Liu, L.

    2011-12-01

    Results of studies of the wave structure of the critical frequencies of the ionospheric F2 layer with periods of planetary waves for two Asian stations—Irkutsk and Wuhan (China)—are presented. Estimates of the appearance frequency, amplitudes, and the lifetime of oscillations with periods typical of planetary waves (2-25 days) are obtained. It is shown that these characteristics depend on the season and place of observation. The appearance of joint periodicities in the critical frequencies at both stations, as well as in the planetary index of geomagnetic activity Ap, is noted.

  16. Low frequency stimulation of the perforant pathway generates anesthesia-specific variations in neural activity and BOLD responses in the rat dentate gyrus

    PubMed Central

    Krautwald, Karla; Angenstein, Frank

    2012-01-01

    To study how various anesthetics affect the relationship between stimulus frequency and generated functional magnetic resonance imaging (fMRI) signals in the rat dentate gyrus, the perforant pathway was electrically stimulated with repetitive low frequency (i.e., 0.625, 1.25, 2.5, 5, and 10 Hz) stimulation trains under isoflurane/N2O, isoflurane, medetomidine, and α-chloralose. During stimulation, the blood oxygen level-dependent signal intensity (BOLD response) and local field potentials in the dentate gyrus were simultaneously recorded to prove whether the present anesthetic controls the generation of a BOLD response via targeting general hemodynamic parameters, by affecting mechanisms of neurovascular coupling, or by disrupting local signal processing. Using this combined electrophysiological/fMRI approach, we found that the threshold frequency (i.e., the minimal frequency required to trigger significant BOLD responses), the optimal frequency (i.e., the frequency that elicit the strongest BOLD response), and the spatial distribution of generated BOLD responses are specific for each anesthetic used. Concurrent with anesthetic-dependent characteristics of the BOLD response, we found the pattern of stimulus-induced neuronal activity in the dentate gyrus is also specific for each anesthetic. Consequently, the anesthetic-specific influence on local signaling processes is the underlying cause for the observation that an identical stimulus elicits different BOLD responses under various anesthetics. PMID:21863039

  17. Low frequency stimulation of the perforant pathway generates anesthesia-specific variations in neural activity and BOLD responses in the rat dentate gyrus.

    PubMed

    Krautwald, Karla; Angenstein, Frank

    2012-02-01

    To study how various anesthetics affect the relationship between stimulus frequency and generated functional magnetic resonance imaging (fMRI) signals in the rat dentate gyrus, the perforant pathway was electrically stimulated with repetitive low frequency (i.e., 0.625, 1.25, 2.5, 5, and 10 Hz) stimulation trains under isoflurane/N(2)O, isoflurane, medetomidine, and α-chloralose. During stimulation, the blood oxygen level-dependent signal intensity (BOLD response) and local field potentials in the dentate gyrus were simultaneously recorded to prove whether the present anesthetic controls the generation of a BOLD response via targeting general hemodynamic parameters, by affecting mechanisms of neurovascular coupling, or by disrupting local signal processing. Using this combined electrophysiological/fMRI approach, we found that the threshold frequency (i.e., the minimal frequency required to trigger significant BOLD responses), the optimal frequency (i.e., the frequency that elicit the strongest BOLD response), and the spatial distribution of generated BOLD responses are specific for each anesthetic used. Concurrent with anesthetic-dependent characteristics of the BOLD response, we found the pattern of stimulus-induced neuronal activity in the dentate gyrus is also specific for each anesthetic. Consequently, the anesthetic-specific influence on local signaling processes is the underlying cause for the observation that an identical stimulus elicits different BOLD responses under various anesthetics. PMID:21863039

  18. Frequency spirals

    NASA Astrophysics Data System (ADS)

    Ottino-Löffler, Bertrand; Strogatz, Steven H.

    2016-09-01

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call "frequency spirals." These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  19. Ultracapacitor separator

    DOEpatents

    Wei, Chang; Jerabek, Elihu Calvin; LeBlanc, Jr., Oliver Harris

    2001-03-06

    An ultracapacitor includes two solid, nonporous current collectors, two porous electrodes separating the collectors, a porous separator between the electrodes and an electrolyte occupying the pores in the electrodes and separator. The electrolyte is a polar aprotic organic solvent and a salt. The porous separator comprises a wet laid cellulosic material.

  20. Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy

    NASA Astrophysics Data System (ADS)

    Vannière, B.; Magny, M.; Joannin, S.; Simonneau, A.; Wirth, S. B.; Hamann, Y.; Chapron, E.; Gilli, A.; Desmet, M.; Anselmetti, F. S.

    2012-09-01

    Two lacustrine sediment cores from Lake Ledro in Northern Italy were studied to produce chronologies of flood events for the past 10 000 yr. For this purpose, we have developed an automatic method that objectively identifies the sedimentary imprint of river floods in the downstream lake basin. The automatic counting of flood deposits was based on colour data extracted from processed core photographs, and the count data were processed to capture the flood signal. Automatic quantification was compared with naked-eye counting. Counts were performed twice on the proximal and distal cores to provide an objective and reproducible record of flood frequency. Geophysical and geochemical analyses made it possible to distinguish event deposits from background sedimentation. Flood frequency and reconstructed sedimentary dynamics were compared with lake-level changes and pollen dynamics inferred from vegetation data. The data suggest a record marked by low flood frequency during the early and middle Holocene (10 000-4500 cal BP). Only modest increases during short intervals are recorded at ca. 8000, 7500, and 7100 cal BP. The last third of the Holocene is characterised by a shift toward increased flood frequency at ca. 4500-4000 cal BP. With the exception of two short intervals around 2900-2500 and 1800-1400 cal BP, which show a slightly reduced number of floods, the trend of increasing flood frequency prevailed until the 20th century, reaching a maximum between the 16th and the 19th centuries. Brief-flood frequency increases recorded during the early and middle Holocene can be attributed to cold climatic oscillations. On a centennial time scale, major changes in flood frequency, such as those observed at ca. 4500 and 500 cal BP, can be attributed to large-scale climatic changes such as the Neo-glacial and Little Ice Age, which are under orbital and possibly solar control. The role of climate as the main forcing factor in flood activity is supported by the lake-level records

  1. AUTOMATIC FREQUENCY CONTROL SYSTEM

    DOEpatents

    Hansen, C.F.; Salisbury, J.D.

    1961-01-10

    A control is described for automatically matching the frequency of a resonant cavity to that of a driving oscillator. The driving oscillator is disconnected from the cavity and a secondary oscillator is actuated in which the cavity is the frequency determining element. A low frequency is mixed with the output of the driving oscillator and the resultant lower and upper sidebands are separately derived. The frequencies of the sidebands are compared with the secondary oscillator frequency. deriving a servo control signal to adjust a tuning element in the cavity and matching the cavity frequency to that of the driving oscillator. The driving oscillator may then be connected to the cavity.

  2. Synchronization of human heart-rate indicators and geomagnetic field variations in the frequency range of 0.5-3.0 mHz

    NASA Astrophysics Data System (ADS)

    Zenchenko, T. A.; Medvedeva, A. A.; Khorseva, N. I.; Breus, T. K.

    2014-12-01

    Fifty-seven experiments have been conducted to monitor the minute indicators of heart rate at rest in 38 practically healthy individuals (9 men and 29 women) from 18 to 58 years old. The duration of each observation period is 60 to 200 min. We have measured the heart rate and the minute-averaged cardiac section durations reflecting the passage of electrical excitation over different parts of myocardium. A comparison of the dynamics of minute values of these physiological parameters with variations of the X and Z components of the geomagnetic field has shown that two-thirds of experiments revealed the synchronization of oscillations in the heart rate and variations in the components of the geomagnetic field. We have revealed both the matching of the observed periods of oscillations ranging between 4 and 30 min and an approximate synchronicity in the times of their appearance and disappearance.

  3. Disentangling the roles of history and local selection in shaping clinal variation of allele frequencies and gene expression in Norway spruce (Picea abies).

    PubMed

    Chen, Jun; Källman, Thomas; Ma, Xiaofei; Gyllenstrand, Niclas; Zaina, Giusi; Morgante, Michele; Bousquet, Jean; Eckert, Andrew; Wegrzyn, Jill; Neale, David; Lagercrantz, Ulf; Lascoux, Martin

    2012-07-01

    Understanding the genetic basis of local adaptation is challenging due to the subtle balance among conflicting evolutionary forces that are involved in its establishment and maintenance. One system with which to tease apart these difficulties is clines in adaptive characters. Here we analyzed genetic and phenotypic variation in bud set, a highly heritable and adaptive trait, among 18 populations of Norway spruce (Picea abies), arrayed along a latitudinal gradient ranging from 47°N to 68°N. We confirmed that variation in bud set is strongly clinal, using a subset of five populations. Genotypes for 137 single-nucleotide polymorphisms (SNPs) chosen from 18 candidate genes putatively affecting bud set and 308 control SNPs chosen from 264 random genes were analyzed for patterns of genetic structure and correlation to environment. Population genetic structure was low (F(ST) = 0.05), but latitudinal patterns were apparent among Scandinavian populations. Hence, part of the observed clinal variation should be attributable to population demography. Conditional on patterns of genetic structure, there was enrichment of SNPs within candidate genes for correlations with latitude. Twenty-nine SNPs were also outliers with respect to F(ST). The enrichment for clinal variation at SNPs within candidate genes (i.e., SNPs in PaGI, PaPhyP, PaPhyN, PaPRR7, and PaFTL2) indicated that local selection in the 18 populations, and/or selection in the ancestral populations from which they were recently derived, shaped the observed cline. Validation of these genes using expression studies also revealed that PaFTL2 expression is significantly associated with latitude, thereby confirming the central role played by this gene in the control of phenology in plants.

  4. Disentangling the Roles of History and Local Selection in Shaping Clinal Variation of Allele Frequencies and Gene Expression in Norway Spruce (Picea abies)

    PubMed Central

    Chen, Jun; Källman, Thomas; Ma, Xiaofei; Gyllenstrand, Niclas; Zaina, Giusi; Morgante, Michele; Bousquet, Jean; Eckert, Andrew; Wegrzyn, Jill; Neale, David; Lagercrantz, Ulf; Lascoux, Martin

    2012-01-01

    Understanding the genetic basis of local adaptation is challenging due to the subtle balance among conflicting evolutionary forces that are involved in its establishment and maintenance. One system with which to tease apart these difficulties is clines in adaptive characters. Here we analyzed genetic and phenotypic variation in bud set, a highly heritable and adaptive trait, among 18 populations of Norway spruce (Picea abies), arrayed along a latitudinal gradient ranging from 47°N to 68°N. We confirmed that variation in bud set is strongly clinal, using a subset of five populations. Genotypes for 137 single-nucleotide polymorphisms (SNPs) chosen from 18 candidate genes putatively affecting bud set and 308 control SNPs chosen from 264 random genes were analyzed for patterns of genetic structure and correlation to environment. Population genetic structure was low (FST = 0.05), but latitudinal patterns were apparent among Scandinavian populations. Hence, part of the observed clinal variation should be attributable to population demography. Conditional on patterns of genetic structure, there was enrichment of SNPs within candidate genes for correlations with latitude. Twenty-nine SNPs were also outliers with respect to FST. The enrichment for clinal variation at SNPs within candidate genes (i.e., SNPs in PaGI, PaPhyP, PaPhyN, PaPRR7, and PaFTL2) indicated that local selection in the 18 populations, and/or selection in the ancestral populations from which they were recently derived, shaped the observed cline. Validation of these genes using expression studies also revealed that PaFTL2 expression is significantly associated with latitude, thereby confirming the central role played by this gene in the control of phenology in plants. PMID:22542968

  5. Automated and visual measurements of estrous behavior and their sources of variation in Holstein heifers. I: Walking activity and behavior frequency.

    PubMed

    Silper, B F; Robles, I; Madureira, A M L; Burnett, T A; Reis, M M; de Passillé, A M; Rushen, J; Cerri, R L A

    2015-07-15

    Holstein heifers (n = 57) were monitored using accelerometers and video observations with the objective of better understanding the behavioral expression of estrus, the variation within and between the heifers, and the possible sources of variation. IceTags recorded walking activity from 7 to 13 months of age. Activity peaks (n = 282) were obtained from a rolling sum of steps within 24-hour periods and validated to be estrus by ovarian ultrasonography. Behavior around activity peak of one estrus for each of 12 heifers was described in detail from video recordings. Baseline behavior was monitored in a corresponding interval 1 week before. Estrus and baseline total steps and steps per hour, estrus relative increase in activity, duration, and interval between episodes were analyzed by descriptive statistics and Spearman rank correlations. Effects of category of baseline walking activity, estrus order (pubertal vs. second and greater episodes), season, hour of estrus onset, and number of heifers simultaneously in estrus were evaluated with proc MIXED. Behavioral changes from baseline to estrus were evaluated by a signed-rank test. Estrus total steps varied greatly (4743 ± 1740; range: 837-10,070), as well as the relative increase in activity (290 ± 160%; range: 30%-1190%). Duration of estrus was 14 ± 4 hours, ranging from 4 to 26 hours. The interval between episodes was the trait that varied the least. Pubertal estrus was shorter and had a smaller relative increase in activity than second and greater episodes (P < 0.05). The number of steps during estrus was greater for heifers of high baseline activity (P < 0.01). Estrus episodes occurring in the winter and starting between 4 PM and 3 AM had the greatest relative increase in activity (P < 0.05). The number of heifers simultaneously in estrus did not influence estrus expression (P > 0.05). The behaviors with greatest change from baseline to estrus were chin rest, sniff, back mount, crossover, accept chin rest, and

  6. CH bond length variations due to the intramolecular environment: a comparison of the results obtained by the method of isolated CH stretching frequencies and by ab initio gradient calculations

    NASA Astrophysics Data System (ADS)

    McKean, Donald C.; Boggs, James E.; Schäfer, Lothar

    1984-05-01

    Two approaches, one experimental and the other theoretical, to the elucidation of CH bond length variation due to the intramolecular environment are compared. The experimental method is based on the concept of isolated CH stretching frequencies while the theoretical method involves the ab initio gradient procedure. Provided molecules of not too dissimilar structure are compared agreement between the two methods is encouragingly satisfactory. The methods are to some extent complementary, the ν isCH method being especially applicable to compounds with heavy atoms (e.g. Br, Ge, etc.) and the ab initio method in cases where isotopic frequency data are lacking. The potential applications of this dual technique approach include assessment of the quality of microwave-based geometries, exploration of link between structure and reactivity and prediction of the structure of these basic units in much larger molecules.

  7. Variations of high frequency parameter of heart rate variability following osteopathic manipulative treatment in healthy subjects compared to control group and sham therapy: randomized controlled trial

    PubMed Central

    Ruffini, Nuria; D'Alessandro, Giandomenico; Mariani, Nicolò; Pollastrelli, Alberto; Cardinali, Lucia; Cerritelli, Francesco

    2015-01-01

    Context: Heart Rate Variability (HRV) indicates how heart rate changes in response to inner and external stimuli. HRV is linked to health status and it is an indirect marker of the autonomic nervous system (ANS) function. Objective: To investigate the influence of osteopathic manipulative treatment (OMT) on cardiac autonomic modulation in healthy subjects, compared with sham therapy and control group. Methods: Sixty-six healthy subjects, both male and female, were included in the present 3-armed randomized placebo controlled within subject cross-over single blinded study. Participants were asymptomatic adults (26.7 ± 8.4 y, 51% male, BMI 18.5 ± 4.8), both smokers and non-smokers and not on medications. At enrollment subjects were randomized in three groups: A, B, C. Standardized structural evaluation followed by a patient need-based osteopathic treatment was performed in the first session of group A and in the second session of group B. Standardized evaluation followed by a protocoled sham treatment was provided in the second session of group A and in the first session of group B. No intervention was performed in the two sessions of group C, acting as a time-control. The trial was registered on clinicaltrials.gov identifier: NCT01908920. Main Outcomes Measures: HRV was calculated from electrocardiography before, during and after the intervention, for a total amount time of 25 min and considering frequency domain as well as linear and non-linear methods as outcome measures. Results: OMT engendered a statistically significant increase of parasympathetic activity, as shown by High Frequency power (p < 0.001), expressed in normalized and absolute unit, and possibly decrease of sympathetic activity, as revealed by Low Frequency power (p < 0.01); results also showed a reduction of Low Frequency/High Frequency ratio (p < 0.001) and Detrended fluctuation scaling exponent (p < 0.05). Conclusions: Findings suggested that OMT can influence ANS activity increasing

  8. Dependence of sandpile avalanche frequency-size distribution on coverage extent and compactness of embedded toppling threshold heterogeneity: implications for the variation of Gutenberg-Richter b value

    NASA Astrophysics Data System (ADS)

    Chiao, L.-Y.; Liu, Q.

    2014-12-01

    The effects of the spatiotemporal evolution of failure threshold heterogeneity on the dynamics of fault criticality, and thus on regional seismogenesis, have attracted strong interest in the field of regional seismotectonics. The heterogeneity might be a manifestation of the macroscopic distribution and multiscale strength variation of asperities, the distinct regional stress level, and (microscopically) heterogeneous fault surface roughness or friction regimes. In this study, rather than attempting to mimic the complex microscale slipping physics on a fault surface, sandpile cellular automata were implemented with a straightforward toppling rule. The objective is to examine the influence of distinct configurations of the embedded heterogeneous toppling threshold field on the global system avalanche event statistics. The examination results revealed that increasing the coverage extent and decreasing the compactness of the heterogeneous failure threshold, rather than the magnitude, range of contrast, diversity, or the geometric configuration of the threshold heterogeneity, leads to a systematic increase in the scaling exponent of the avalanche event power law statistics, implying the importance of mutual interaction among toppling sites with distinct thresholds. For tectonic provinces with differing stress regimes evolving spatio temporally, it is postulated that the distinct extent and compactness of the heterogeneous failure threshold are critical factors that manifest in the reported dynamic variations of seismicity scaling.

  9. The evolution of polyandry: patterns of genotypic variation in female mating frequency, male fertilization success and a test of the sexy-sperm hypothesis.

    PubMed

    Simmons, L W

    2003-07-01

    The sexy-sperm hypothesis predicts that females obtain indirect benefits for their offspring via polyandy, in the form of increased fertilization success for their sons. I use a quantitative genetic approach to test the sexy-sperm hypothesis using the field cricket Teleogryllus oceanicus. Previous studies of this species have shown considerable phenotypic variation in fertilization success when two or more males compete. There were high broad-sense heritabilities for both paternity and polyandry. Patterns of genotypic variance were consistent with X-linked inheritance and/or maternal effects on these traits. The genetic architecture therefore precludes the evolution of polyandry via a sexy-sperm process. Thus the positive genetic correlation between paternity in sons and polyandry in daughters predicted by the sexy-sperm hypothesis was absent. There was significant heritable variation in the investment by females in ovaries and by males in the accessory gland. Surprisingly there was a very strong genetic correlation between these two traits. The significance of this genetic correlation for the coevolution of male seminal products and polyandry is discussed.

  10. Multi-scale harmonic model for solar and climate cyclical variation throughout the Holocene based on Jupiter-Saturn tidal frequencies plus the 11-year solar dynamo cycle

    NASA Astrophysics Data System (ADS)

    Scafetta, Nicola

    2012-05-01

    The Schwabe frequency band of the Zurich sunspot record since 1749 is found to be made of three major cycles with periods of about 9.98, 10.9 and 11.86 years. The side frequencies appear to be closely related to the spring tidal period of Jupiter and Saturn (range between 9.5 and 10.5 years, and median 9.93 years) and to the tidal sidereal period of Jupiter (about 11.86 years). The central cycle may be associated to a quasi-11-year solar dynamo cycle that appears to be approximately synchronized to the average of the two planetary frequencies. A simplified harmonic constituent model based on the above two planetary tidal frequencies and on the exact dates of Jupiter and Saturn planetary tidal phases, plus a theoretically deduced 10.87-year central cycle reveals complex quasi-periodic interference/beat patterns. The major beat periods occur at about 115, 61 and 130 years, plus a quasi-millennial large beat cycle around 983 years. We show that equivalent synchronized cycles are found in cosmogenic records used to reconstruct solar activity and in proxy climate records throughout the Holocene (last 12,000 years) up to now. The quasi-secular beat oscillations hindcast reasonably well the known prolonged periods of low solar activity during the last millennium such as the Oort, Wolf, Spörer, Maunder and Dalton minima, as well as the 17 115-year long oscillations found in a detailed temperature reconstruction of the Northern Hemisphere covering the last 2000 years. The millennial three-frequency beat cycle hindcasts equivalent solar and climate cycles for 12,000 years. Finally, the harmonic model herein proposed reconstructs the prolonged solar minima that occurred during 1900-1920 and 1960-1980 and the secular solar maxima around 1870-1890, 1940-1950 and 1995-2005 and a secular upward trending during the 20th century: this modulated trending agrees well with some solar proxy model, with the ACRIM TSI satellite composite and with the global surface temperature

  11. Amplitude and frequency variations of oscillation modes in the pulsating DB white dwarf star KIC 08626021. The likely signature of nonlinear resonant mode coupling

    NASA Astrophysics Data System (ADS)

    Zong, W.; Charpinet, S.; Vauclair, G.; Giammichele, N.; Van Grootel, V.

    2016-01-01

    Context. The signatures of nonlinear effects affecting stellar oscillations are difficult to observe from ground observatories because of the lack of continuous high-precision photometric data spanning extended enough time baselines. The unprecedented photometric quality and coverage provided by the Kepler spacecraft offers new opportunities to search for these phenomena. Aims: We use the Kepler data accumulated on the pulsating DB white dwarf KIC 08626021 to explore in detail the stability of its oscillation modes, searching, in particular, for evidence of nonlinear behaviors. Methods: We analyze nearly two years of uninterrupted short-cadence data, concentrating on identified triplets that are caused by stellar rotation and that show intriguing behaviors during the course of the observations. Results: We find clear signatures of nonlinear effects that could be attributed to resonant mode coupling mechanisms. These couplings occur between the components of the triplets and can induce different types of behaviors. We first notice that a structure at 3681 μHz, identified as a triplet in previous published studies, is in fact forming a doublet, with the third component being an independent mode. We find that a triplet at 4310 μHz and this doublet at 3681 μHz (most likely the two visible components of an incomplete triplet) have clear periodic frequency and amplitude modulations, which are typical of the so-called intermediate regime of the resonance, with timescales consistent with theoretical expectations. Another triplet at 5073 μHz is likely in a narrow transitory regime in which the amplitudes are modulated while the frequencies are locked. Using nonadiabatic pulsation calculations, based on a model representative of KIC 08626021 to evaluate the linear growth rates of the modes in the triplets, we also provide quantitative information that could be useful for future comparisons with numerical solutions of the amplitude equations. Conclusions: The observed

  12. Acoustophoresis separation method

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S. (Inventor)

    1993-01-01

    A method and apparatus are provided for acoustophoresis, i.e., the separation of species via acoustic waves. An ultrasonic transducer applies an acoustic wave to one end of a sample container containing at least two species having different acoustic absorptions. The wave has a frequency tuned to or harmonized with the point of resonance of the species to be separated. This wave causes the species to be driven to an opposite end of the sample container for removal. A second ultrasonic transducer may be provided to apply a second, oppositely directed acoustic wave to prevent undesired streaming. In addition, a radio frequency tuned to the mechanical resonance and coupled with a magnetic field can serve to identify a species in a medium comprising species with similar absorption coefficients, whereby an acoustic wave having a frequency corresponding to this gyrational rate can then be applied to sweep the identified species to one end of the container for removal.

  13. Crosstalk in a KID Array Caused by the Thickness Variation of Superconducting Metal

    NASA Astrophysics Data System (ADS)

    Adane, A.; Boucher, C.; Coiffard, G.; Leclercq, S.; Schuster, K. F.; Goupy, J.; Calvo, M.; Hoarau, C.; Monfardini, A.

    2016-07-01

    The work presented in this paper is focused on the improvement of the kinetic detectors used on NIKA2 instrument (New IRAM KID array 2). Based on the simulation and low temperature measurements, it aims at showing how the variations of the superconducting metal corrupt the frequency comb of the kinetic Inductance detectors (KID) in the frequency range (between 1 and 3 GHz), i.e., how the superconducting metal inhomogeneity induces the resonance-to-resonance cross-coupling which deteriorates the homogeneity of the resonance quality factor and the frequency resonance separation. Solutions are then proposed to fight against the effect of these metallic variations when designing the KID array.

  14. Harmonic model for solar and climate cyclical variation throughout the Holocene based on Jupiter-Saturn tidal frequencies plus the 11-year solar dynamo cycle

    NASA Astrophysics Data System (ADS)

    Scafetta, N.

    2012-12-01

    We show that the Schwabe frequency band of the Zurich sunspot record since 1749 is made of three major cycles that are closely related to the spring tidal period of Jupiter and Saturn (~9.93 year), to the tidal sidereal period of Jupiter (about 11.86 years) and to a central cycle that may be associated to a quasi-11-year solar dynamo cycle. The central harmonic is approximately synchronized to the average of the two planetary frequencies. A harmonic model based on the above two planetary tidal frequencies and on the exact dates of Jupiter and Saturn planetary tidal phases, plus a theoretically deduced 10.87-year central cycle reveals major beat periods occurring at about 115, 61 and 130 years, plus a quasi-millennial large beat cycle around 983 years. Equivalent synchronized cycles are found in cosmogenic solar proxy records used to reconstruct solar activity and in proxy climate records throughout the Holocene (last 12,000 years) up to now. The quasi-secular beat oscillations hindcast reasonably well the known prolonged periods of low solar activity during the last millennium such as the Oort, Wolf, Sporer, Maunder and Dalton minima, as well as the 17 115-year long oscillations found in a detailed temperature reconstruction of the Northern Hemisphere covering the last 2000 years. The millennial three-frequency beat cycle hindcasts equivalent solar and climate cycles for 12,000 years. Finally, the harmonic model herein proposed reconstructs the prolonged solar minima around 1900-1920 and 1960-1980, the secular solar maxima around 1870-1890, 1940-1950 and 1995-2005, and a secular upward trending during the 20th century. The latter modulated trending agrees well with some solar proxy model, with the ACRIM TSI satellite composite and with the global surface temperature modulation since 1850. The model forecasts a new prolonged solar minimum during 2020-2045, which is produced by the minima of both the 61 and 115-year reconstructed cycles. Finally, the model predicts

  15. Variation of availability and frequency of emergency physician-performed ultrasonography between adult and pediatric patients in the academic emergency department in Korea

    PubMed Central

    Ahn, Chiwon; Kim, Changsun; Kang, Bo Seung; Choi, Hyuk Joong; Cho, Jun Hwi

    2015-01-01

    Objective This study investigates the availability and frequency of emergency physician-performed ultrasonography (USG) in the emergency department (ED) and the status of USG training programs in emergency medicine residencies in academic EDs in Korea. Methods In spring 2014, a link to a 16-question, multiple-choice, and rating scale web-based survey was e-mailed to all 97 academic ED residency training directors in Korea. Results The response rate was 83.5% (81/97). All respondents had their own USG machines in the ED. In total, 82.7% of respondents reported that emergency physician-performed adult USGs were usually conducted daily, whereas only 23.6% performed pediatric USGs daily. Moreover, 55.5% performed pediatric USG fewer than once a week. 74.1% of respondents had education programs for adult USG in residency training, but only 21.0% had programs for pediatric USG. There was a high association between the presence of education programs and the use of USG in both groups. The faculty members who most commonly participated in teaching ED residents how to perform USG were emergency physicians (67.9%). Only 17.3% of respondents reported that they always supported a quality assurance process. The training directors generally agreed with the advantages in emergency physician-performed USGs. Conclusion The availability of ultrasound machines was high both for adult and pediatric EDs. Nevertheless, the frequency of Emergency physician-performed USG for pediatric patients was low, which was related to the lack of the training programs for treating pediatric patients.

  16. Prefrontal activity during working memory is modulated by the interaction of variation in CB1 and COX2 coding genes and correlates with frequency of cannabis use.

    PubMed

    Taurisano, Paolo; Antonucci, Linda A; Fazio, Leonardo; Rampino, Antonio; Romano, Raffaella; Porcelli, Annamaria; Masellis, Rita; Colizzi, Marco; Quarto, Tiziana; Torretta, Silvia; Di Giorgio, Annabella; Pergola, Giulio; Bertolino, Alessandro; Blasi, Giuseppe

    2016-08-01

    The CB1 cannabinoid receptor is targeted in the brain by endocannabinoids under physiological conditions as well as by delta9-tetrahydrocannabinol under cannabis use. Furthermore, its signaling appears to affect brain cognitive processing. Recent findings highlight a crucial role of cyclooxygenase-2 (COX-2) in the mechanism of intraneuronal CB1 signaling transduction, while others indicate that two single nucleotide polymorphisms (SNPs) (rs1406977 and rs20417) modulate expression of CB1 (CNR1) and COX-2 (PTGS2) coding genes, respectively. Here, our aim was to use fMRI to investigate in healthy humans whether these SNPs interact in modulating prefrontal activity during working memory processing and if this modulation is linked with cannabis use. We recruited 242 healthy subjects genotyped for CNR1 rs1406977 and PTGS2 rs20417 that performed the N-back working memory task during fMRI and were interviewed using the Cannabis Experience Questionnaire (CEQ). We found that the interaction between CNR1 rs1406977 and PTGS2 rs20417 is associated with dorsolateral prefrontal cortex (DLPFC) activity such that specific genotype configurations (CNR1 C carriers/PTGS2 C carriers and CNR1 TT/PTGS2 GG) predict lower cortical response versus others in spite of similar behavioral accuracy. Furthermore, DLPFC activity in the cluster associated with the CNR1 by PTGS2 interaction was negatively correlated with behavioral efficiency and positively correlated with frequency of cannabis use in cannabis users. These results suggest that a genetically modulated balancing of signaling within the CB1-COX-2 pathway may reflect on more or less efficient patterns of prefrontal activity during working memory. Frequency of cannabis use may be a factor for further modulation of CNR1/PTGS2-mediated cortical processing associated with this cognitive process. PMID:27261878

  17. A Mechanism for Frequency Modulation in Songbirds Shared with Humans

    PubMed Central

    Margoliash, Daniel

    2013-01-01

    In most animals that vocalize, control of fundamental frequency is a key element for effective communication. In humans, subglottal pressure controls vocal intensity but also influences fundamental frequency during phonation. Given the underlying similarities in the biomechanical mechanisms of vocalization in humans and songbirds, songbirds offer an attractive opportunity to study frequency modulation by pressure. Here, we present a novel technique for dynamic control of subsyringeal pressure in zebra finches. By regulating the opening of a custom-built fast valve connected to the air sac system, we achieved partial or total silencing of specific syllables, and could modify syllabic acoustics through more complex manipulations of air sac pressure. We also observed that more nuanced pressure variations over a limited interval during production of a syllable concomitantly affected the frequency of that syllable segment. These results can be explained in terms of a mathematical model for phonation that incorporates a nonlinear description for the vocal source capable of generating the observed frequency modulations induced by pressure variations. We conclude that the observed interaction between pressure and frequency was a feature of the source, not a result of feedback control. Our results indicate that, beyond regulating phonation or its absence, regulation of pressure is important for control of fundamental frequencies of vocalizations. Thus, although there are separate brainstem pathways for syringeal and respiratory control of song production, both can affect airflow and frequency. We hypothesize that the control of pressure and frequency is combined holistically at higher levels of the vocalization pathways. PMID:23825417

  18. Dosimetry of infant exposure to power-frequency magnetic fields: variation of 99th percentile induced electric field value by posture and skin-to-skin contact.

    PubMed

    Li, Congsheng; Wu, Tongning

    2015-04-01

    Infant exposure to 50 Hz magnetic fields from power lines was numerically analyzed in this study. Dosimetric variability due to posture and skin-to-skin contact was evaluated using human anatomical models including a recently developed model of a 12-months-old infant. As proposed by the International Commission on Non-Ionizing Radiation Protection, the induced E-field strength (99th percentile value, E99 ) for the central nerve systems (E99_CNS ) and peripheral nerve system (E99_PNS ), were used as metrics. Results showed that the single (free of contact with others) infant model has lower E99 (E99_CNS and E99_PNS inclusive) compared with single adult and child models when exposed to the same power-frequency magnetic field. Also, studied postures of sitting, standing, or arm-up, would not change E99 _PNS . However, skin-to-skin contact with other models could significantly raise induced E-field strength in the infant (e.g., contact on 0.93% of the infant's total surface increased E99_PNS by 213%). Simulations with canonical models were conducted to assess different factors contributing to the E99 enhancement. Results indicated the importance of thoroughly investigating the conservativeness of current safety guidelines in the case of skin-to-skin contact, especially with infants.

  19. Char separator

    DOEpatents

    Matthews, Francis T.

    1979-01-01

    Particulates removed from the flue gases produced in a fluidized-bed furnace are separated into high-and low-density portions. The low-density portion is predominantly char, and it is returned to the furnace or burned in a separate carbon burnup cell. The high-density portion, which is predominantly limestone products and ash, is discarded or reprocessed. According to another version, the material drained from the bed is separated, the resulting high-and low-density portions being treated in a manner similar to that in which the flue-gas particulates are treated.

  20. CENTRIFUGAL SEPARATORS

    DOEpatents

    Skarstrom, C.

    1959-03-10

    A centrifugal separator is described for separating gaseous mixtures where the temperature gradients both longitudinally and radially of the centrifuge may be controlled effectively to produce a maximum separation of the process gases flowing through. Tbe invention provides for the balancing of increases and decreases in temperature in various zones of the centrifuge chamber as the result of compression and expansions respectively, of process gases and may be employed effectively both to neutralize harmful temperature gradients and to utilize beneficial temperaturc gradients within the centrifuge.

  1. Spatial and temporal variations of new particle formation in East Asia using an NPF-explicit WRF-chem model: North-south contrast in new particle formation frequency

    SciTech Connect

    Matsui, H.; Koike, Makoto; Takegawa, Nobuyuki; Kondo, Yutaka; Takami, A.; Takamura, T.; Yoon, Soh-joung; Kim, S. W.; Lim, Hyuntae; Fast, Jerome D.

    2013-10-27

    The new particle formation (NPF)-explicit version of the WRF-chem model, which we developed recently, can calculate the growth and sink of nucleated clusters explicitly with 20 aerosol size bins from 1 nm to 10 μm. In this study, the model is used to understand spatial and temporal variations of the frequency of NPF events and the concentrations of aerosols (condensation nuclei, CN) and cloud condensation nuclei (CCN) within the boundary layer in East Asia in spring 2009. Model simulations show distinct north-south contrast in the frequency and mechanism of NPF in East Asia. NPF mostly occurred over limited periods and regions between 30° and 45°N, such as northeast China, Korea, and Japan, including regions around active volcanoes (Miyakejima and Sakurajima). At these latitudes, NPF was considerably suppressed by high concentrations of preexisting particles under stagnant air conditions associated with high-pressure systems, while nucleation occurred more extensively on most days during the simulation period. Conversely, neither nucleation nor NPF occurred frequently south of 30°N because of lower SO2 emissions and H2SO4 concentrations. The period-averaged NPF frequency was 3 times higher at latitudes of 30° - 45°N than at latitudes of 20° - 30°N. The north-south contrast of NPF frequency is validated by surface measurements in outflow regions in East Asia. The period- and domain-averaged contribution of secondary particles is estimated to be 44% for CN (> 10 nm) and 26% for CCN at a supersaturation of 1.0% in our simulation, though the contribution is highly sensitive to the magnitudes and size distributions of primary aerosol emissions and the coefficients in the nucleation parameterizations.

  2. Parametric Effects of Word Frequency in Memory for Mixed Frequency Lists

    ERIC Educational Resources Information Center

    Lohnas, Lynn J.; Kahana, Michael J.

    2013-01-01

    The "word frequency paradox" refers to the finding that low frequency words are better recognized than high frequency words yet high frequency words are better recalled than low frequency words. Rather than comparing separate groups of low and high frequency words, we sought to quantify the functional relation between word frequency and…

  3. Increased Frequency of De Novo Copy Number Variations in Congenital Heart Disease by Integrative Analysis of SNP Array and Exome Sequence Data

    PubMed Central

    Rodriguez-Murillo, Laura; Fromer, Menachem; Mazaika, Erica; Vardarajan, Badri; Italia, Michael; Leipzig, Jeremy; DePalma, Steven R.; Golhar, Ryan; Sanders, Stephan J.; Yamrom, Boris; Ronemus, Michael; Iossifov, Ivan; Willsey, A. Jeremy; State, Matthew W.; Kaltman, Jonathan R.; White, Peter S.; Shen, Yufeng; Warburton, Dorothy; Brueckner, Martina; Seidman, Christine; Goldmuntz, Elizabeth; Gelb, Bruce D.; Lifton, Richard; Seidman, Jonathan; Hakonarson, Hakon; Chung, Wendy K.

    2014-01-01

    Rationale Congenital heart disease (CHD) is among the most common birth defects. Most cases are of unknown etiology. Objective To determine the contribution of de novo copy number variants (CNVs) in the etiology of sporadic CHD. Methods and Results We studied 538 CHD trios using genome-wide dense single nucleotide polymorphism (SNP) arrays and/or whole exome sequencing (WES). Results were experimentally validated using digital droplet PCR. We compared validated CNVs in CHD cases to CNVs in 1,301 healthy control trios. The two complementary high-resolution technologies identified 63 validated de novo CNVs in 51 CHD cases. A significant increase in CNV burden was observed when comparing CHD trios with healthy trios, using either SNP array (p=7x10−5, Odds Ratio (OR)=4.6) or WES data (p=6x10−4, OR=3.5) and remained after removing 16% of de novo CNV loci previously reported as pathogenic (p=0.02, OR=2.7). We observed recurrent de novo CNVs on 15q11.2 encompassing CYFIP1, NIPA1, and NIPA2 and single de novo CNVs encompassing DUSP1, JUN, JUP, MED15, MED9, PTPRE SREBF1, TOP2A, and ZEB2, genes that interact with established CHD proteins NKX2-5 and GATA4. Integrating de novo variants in WES and CNV data suggests that ETS1 is the pathogenic gene altered by 11q24.2-q25 deletions in Jacobsen syndrome and that CTBP2 is the pathogenic gene in 10q sub-telomeric deletions. Conclusions We demonstrate a significantly increased frequency of rare de novo CNVs in CHD patients compared with healthy controls and suggest several novel genetic loci for CHD. PMID:25205790

  4. Stereoisomers Separation

    NASA Astrophysics Data System (ADS)

    Wieczorek, Piotr

    The use of capillary electrophoresis for enantiomer separation and optical purity determination is presented. The contents start with basic information about the nature of stereoizomers and the mechanism of enantioseparation using capillary electrophoresis techniques. The molecules to be separated show identical chemical structure and electrochemical behavior. Therefore, the chiral recognition of enantiomers is possible only by bonding to chiral selector and the separation based on very small differences in complexation energies of diastereomer complexes formed. This method is useful for this purpose due to the fact that different compounds can be used as chiral selectors. The mostly used chiral selectors like cyclodextrins, crown ethers, chiral surfactants, macrocyclic antibiotics, transition metal complexes, natural, and synthetic polymers and their application for this purpose is also discussed. Finally, examples of practical applications of electromigration techniques for enantiomers separation and determination are presented.

  5. Map Separates

    USGS Publications Warehouse

    ,

    2001-01-01

    U.S. Geological Survey (USGS) topographic maps are printed using up to six colors (black, blue, green, red, brown, and purple). To prepare your own maps or artwork based on maps, you can order separate black-and-white film positives or negatives for any color printed on a USGS topographic map, or for one or more of the groups of related features printed in the same color on the map (such as drainage and drainage names from the blue plate.) In this document, examples are shown with appropriate ink color to illustrate the various separates. When purchased, separates are black-and-white film negatives or positives. After you receive a film separate or composite from the USGS, you can crop, enlarge or reduce, and edit to add or remove details to suit your special needs. For example, you can adapt the separates for making regional and local planning maps or for doing many kinds of studies or promotions by using the features you select and then printing them in colors of your choice.

  6. Ionospheric very low frequency transmitter

    SciTech Connect

    Kuo, Spencer P.

    2015-02-15

    The theme of this paper is to establish a reliable ionospheric very low frequency (VLF) transmitter, which is also broad band. Two approaches are studied that generate VLF waves in the ionosphere. The first, classic approach employs a ground-based HF heater to directly modulate the high latitude ionospheric, or auroral electrojet. In the classic approach, the intensity-modulated HF heater induces an alternating current in the electrojet, which serves as a virtual antenna to transmit VLF waves. The spatial and temporal variations of the electrojet impact the reliability of the classic approach. The second, beat-wave approach also employs a ground-based HF heater; however, in this approach, the heater operates in a continuous wave mode at two HF frequencies separated by the desired VLF frequency. Theories for both approaches are formulated, calculations performed with numerical model simulations, and the calculations are compared to experimental results. Theory for the classic approach shows that an HF heater wave, intensity-modulated at VLF, modulates the electron temperature dependent electrical conductivity of the ionospheric electrojet, which, in turn, induces an ac electrojet current. Thus, the electrojet becomes a virtual VLF antenna. The numerical results show that the radiation intensity of the modulated electrojet decreases with an increase in VLF radiation frequency. Theory for the beat wave approach shows that the VLF radiation intensity depends upon the HF heater intensity rather than the electrojet strength, and yet this approach can also modulate the electrojet when present. HF heater experiments were conducted for both the intensity modulated and beat wave approaches. VLF radiations were generated and the experimental results confirm the numerical simulations. Theory and experimental results both show that in the absence of the electrojet, VLF radiation from the F-region is generated via the beat wave approach. Additionally, the beat wave approach

  7. Isotope separation

    DOEpatents

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  8. ISOTOPE SEPARATORS

    DOEpatents

    Bacon, C.G.

    1958-08-26

    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  9. SEPARATION PROCESS

    DOEpatents

    Stoughton, R.W.

    1961-10-24

    A process for separating tetravalent plutonium from aqueous solutions and from niobium and zirconium by precipitation on lanthanum oxalate is described. The oxalate ions of the precipitate may be decomposed by heating in the presence of an oxidizing agent, forming a plutonium compound readily soluble in acid. (AEC)

  10. Plasma separation

    NASA Technical Reports Server (NTRS)

    Steurer, Wolfgang

    1992-01-01

    This process employs a thermal plasma for the separation and production of oxygen and metals. It is a continuous process that requires no consumables and relies entirely on space resources. The almost complete absence of waste renders it relatively clean. It can be turned on or off without any undesirable side effects or residues. The prime disadvantage is its high power consumption.

  11. b values and ω−γ seismic source models: Implications for tectonic stress variations along active crustal fault zones and the estimation of high-frequency strong ground motion

    USGS Publications Warehouse

    Hanks, Thomas C.

    1979-01-01

    In this study the tectonic stress along active crustal fault zones is taken to be of the form , where  is the average tectonic stress at depth y and Δσp(x, y) is a seismologically observable, essentially random function of both fault plane coordinates; the stress differences arising in the course of crustal faulting are derived from Δσp(x, y). Empirically known frequency of occurrence statistics, moment-magnitude relationships, and the constancy of earthquake stress drops may be used to infer that the number of earthquakes N of dimension ≥r is of the form N ∼ 1/r2 and that the spectral composition of Δσp(x, y) is of the form , where  is the two-dimensional Fourier transform of Δσp(x, y) expressed in radial wave number k. The γ = 2 model of the far-field shear wave displacement spectrum is consistent with the spectral composition , provided that the number of contributions to the spectral representation of the radiated field at frequency ƒ goes as (k/k0)2, consistent with the quasi-static frequency of occurrence relation N ∼ 1/r2;k0 is a reference wave number associated with the reciprocal source dimension. Separately, a variety of seismologic observations suggests that the γ = 2 model is the one generally, although certainly not always, applicable to the high-frequency spectral decay of the far-field radiation of earthquakes. In this framework, then, b values near 1, the general validity of the γ = 2 model, and the constancy of earthquake stress drops independent of size are all related to the average spectral composition of. Should one of these change as a result of premonitory effects leading to failure, as has been specifically proposed for b values, it seems likely that one or all of the other characteristics will change as well from their normative values. Irrespective of these associations, the far-field, high-frequency shear radiation for the γ = 2 model in the presence of anelastic attenuation may be interpreted as

  12. Laser frequency offset synthesizer

    NASA Astrophysics Data System (ADS)

    Lewis, D. A.; Evans, R. M.; Finn, M. A.

    1985-01-01

    A method is reported for locking the frequency difference of two lasers with an accuracy of 0.5 kHz or less over a one-second interval which is simple, stable, and relatively free from systematic errors. Two 633 nm He-Ne lasers are used, one with a fixed frequency and the other tunable. The beat frequency between the lasers is controlled by a voltage applied to a piezoelectric device which varies the cavity length of the tunable laser. This variable beat frequency, scaled by a computer-controlled modulus, is equivalent to a synthesizer. This approach eliminates the need for a separate external frequency synthesizer; furthermore, the phase detection process occurs at a relatively low frequency, making the required electronics simple and straightforward.

  13. Spectral Separation of the Turbofan Engine Coherent Combustion Noise Component

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    2008-01-01

    The core noise components of a dual spool turbofan engine (Honeywell TECH977) were separated by the use of a coherence function. A source location technique based on adjusting the time delay between the combustor pressure sensor signal and the far-field microphone signal to maximize the coherence and remove as much variation of the phase angle with frequency as possible was used. While adjusting the time delay to maximize the coherence and minimize the cross spectrum phase angle variation with frequency, the discovery was made that for the 130 microphone a 90.027 ms time shift worked best for the frequency band from 0 to 200 Hz while a 86.975 ms time shift worked best for the frequency band from 200 to 400 Hz. Since the 0 to 200 Hz band signal took more time to travel the same distance, it is slower than the 200 to 400 Hz band signal. This suggests the 0 to 200 Hz coherent cross spectral density band is partly due to indirect combustion noise attributed to hot spots interacting with the turbine. The signal in the 200 to 400 Hz frequency band is attributed mostly to direct combustion noise.

  14. Gas separating

    DOEpatents

    Gollan, Arye

    1988-01-01

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  15. Gas separating

    DOEpatents

    Gollan, Arye Z. [Newton, MA

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  16. Separation system

    DOEpatents

    Rubin, Leslie S.

    1986-01-01

    A separation system for dewatering radioactive waste materials includes a disposal container, drive structure for receiving the container, and means for releasably attaching the container to the drive structure. Separation structure disposed in the container adjacent the inner surface of the side wall structure retains solids while allowing passage of liquids. Inlet port structure in the container top wall is normally closed by first valve structure that is centrifugally actuated to open the inlet port and discharge port structure at the container periphery receives liquid that passes through the separation structure and is normally closed by second valve structure that is centrifugally actuated to open the discharge ports. The container also includes coupling structure for releasable engagement with the centrifugal drive structure. Centrifugal force produced when the container is driven in rotation by the drive structure opens the valve structures, and radioactive waste material introduced into the container through the open inlet port is dewatered, and the waste is compacted. The ports are automatically closed by the valves when the container drum is not subjected to centrifugal force such that containment effectiveness is enhanced and exposure of personnel to radioactive materials is minimized.

  17. Component separations.

    PubMed

    Heller, Lior; McNichols, Colton H; Ramirez, Oscar M

    2012-02-01

    Component separation is a technique used to provide adequate coverage for midline abdominal wall defects such as a large ventral hernia. This surgical technique is based on subcutaneous lateral dissection, fasciotomy lateral to the rectus abdominis muscle, and dissection on the plane between external and internal oblique muscles with medial advancement of the block that includes the rectus muscle and its fascia. This release allows for medial advancement of the fascia and closure of up to 20-cm wide defects in the midline area. Since its original description, components separation technique underwent multiple modifications with the ultimate goal to decrease the morbidity associated with the traditional procedure. The extensive subcutaneous lateral dissection had been associated with ischemia of the midline skin edges, wound dehiscence, infection, and seroma. Although the current trend is to proceed with minimally invasive component separation and to reinforce the fascia with mesh, the basic principles of the techniques as described by Ramirez et al in 1990 have not changed over the years. Surgeons who deal with the management of abdominal wall defects are highly encouraged to include this technique in their collection of treatment options.

  18. Frequency, Gradience, and Variation in Consonant Insertion

    ERIC Educational Resources Information Center

    An, Young-ran

    2010-01-01

    This dissertation addresses the extent to which linguistic behavior can be described in terms of the projection of patterns from existing lexical items, through an investigation of Korean reduplication. Korean has a productive pattern of reduplication in which a consonant is inserted in a vowel-initial base, illustrated by forms such as "alok"--"t…

  19. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

    Sugg, Frank E. (Inventor); Graham, Lloyd J. (Inventor)

    1988-01-01

    In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

  20. Gas separating

    DOEpatents

    Gollan, A.

    1988-03-29

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  1. Gas separating

    DOEpatents

    Gollan, A.Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  2. Complex Signal Kurtosis and Independent Component Analysis for Wideband Radio Frequency Interference Detection

    NASA Technical Reports Server (NTRS)

    Schoenwald, Adam; Mohammed, Priscilla; Bradley, Damon; Piepmeier, Jeffrey; Wong, Englin; Gholian, Armen

    2016-01-01

    Radio-frequency interference (RFI) has negatively implicated scientific measurements across a wide variation passive remote sensing satellites. This has been observed in the L-band radiometers SMOS, Aquarius and more recently, SMAP [1, 2]. RFI has also been observed at higher frequencies such as K band [3]. Improvements in technology have allowed wider bandwidth digital back ends for passive microwave radiometry. A complex signal kurtosis radio frequency interference detector was developed to help identify corrupted measurements [4]. This work explores the use of ICA (Independent Component Analysis) as a blind source separation technique to pre-process radiometric signals for use with the previously developed real and complex signal kurtosis detectors.

  3. Particle separation

    NASA Technical Reports Server (NTRS)

    Moosmuller, Hans (Inventor); Chakrabarty, Rajan K. (Inventor); Arnott, W. Patrick (Inventor)

    2011-01-01

    Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

  4. Particle separation

    DOEpatents

    Moosmuller, Hans; Chakrabarty, Rajan K.; Arnott, W. Patrick

    2011-04-26

    Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

  5. Analysis of L5 phase variations in GPS IIF satellites by the raw observation PPP approach

    NASA Astrophysics Data System (ADS)

    Liu, Sha; Becker, Matthias

    2015-04-01

    GPS modernization along with Glonass modernization and the emerging Galileo and Compass system has been highly anticipated by every GNSS user since several years. The third civilian L5 signal transmitted by the modernized GPS satellites brings us to the GNSS multi-frequency era. The first GPS IIF satellite was launched in May 2010, until now there are eight block IIF satellites in service and the remaining four IIF satellites are planned to be launched by 2016. The introduction of the third frequency to GPS and the usage of advanced atomic clocks not only provide the users more possibilities but also enable higher positioning accuracy. Nevertheless phase variations are found on the new L5 observation of GPS SVN62. Further investigations suggest that the variations of this satellite are strongly dependent on the satellite inner temperature variation caused by sun illumination. Besides achieving precise positioning accuracy, PPP is also frequently used as a tool to analyze and evaluate various GNSS errors, for instance, tropospheric delays and receiver clock errors. Other than with differential GNSS, it is possible to separate different errors and to identify the error sources with PPP. Conventional PPP is based on the ionosphere-free linear combination, in order to eliminate the first-order ionospheric delays. However only dual frequencies can be used to build ionosphere-free linear combination, which leads to the waste of the information on the third frequency. Furthermore, the frequency dependent errors can not be separated and traced. A new PPP approach that avoids using any linear combination is proposed recently, which is called the raw observation PPP. One advantage of the raw observation PPP approach is that data of all frequencies and all GNSS systems can be jointly used. In addition, the frequency dependent errors are possible to be separated, identified and analyzed. In this paper the raw observation PPP is utilized to analyze the phase variations on L5

  6. Radioactive-gas separation technique

    NASA Technical Reports Server (NTRS)

    Haney, R.; King, K. J.; Nellis, D. O.; Nisson, R. S.; Robling, P.; Womack, W.

    1977-01-01

    Cryogenic technique recovers gases inexpensively. Method uses differences in vapor pressures, melting points, and boiling points of components in gaseous mixture. Series of temperature and pressure variations converts gases independently to solid and liquid states, thereby simplifying separation. Apparatus uses readily available cryogen and does not require expensive refrigeration equipment.

  7. Fluency Variation in Adolescents

    ERIC Educational Resources Information Center

    De Andrade, Claudia Regina Furquim; Martins, Vanessa De Oliveira

    2007-01-01

    The Speech Fluency Profile of fluent adolescent speakers of Brazilian Portuguese, were examined with respect to gender and neurolinguistic variations. Speech samples of 130 male and female adolescents, aged between 12;0 and 17;11 years were gathered. They were analysed according to type of speech disruption; speech rate; and frequency of speech…

  8. 47 CFR 87.287 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequencies. 87.287 Section 87.287... Data Link Land Test Stations § 87.287 Frequencies. (a) The frequencies assignable to aircraft data link..., 136.925 MHz, 136.950 MHz, and 136.975 MHz. Interstitial frequencies separated by 8.33 kilohertz...

  9. 47 CFR 24.135 - Frequency stability.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Frequency stability. 24.135 Section 24.135... SERVICES Narrowband PCS § 24.135 Frequency stability. (a) The frequency stability of the transmitter shall be maintained within ±0.0001 percent (±1 ppm) of the center frequency over a temperature variation...

  10. 47 CFR 24.135 - Frequency stability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Frequency stability. 24.135 Section 24.135... SERVICES Narrowband PCS § 24.135 Frequency stability. (a) The frequency stability of the transmitter shall be maintained within ±0.0001 percent (±1 ppm) of the center frequency over a temperature variation...

  11. 47 CFR 24.135 - Frequency stability.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Frequency stability. 24.135 Section 24.135... SERVICES Narrowband PCS § 24.135 Frequency stability. (a) The frequency stability of the transmitter shall be maintained within ±0.0001 percent (±1 ppm) of the center frequency over a temperature variation...

  12. 47 CFR 24.135 - Frequency stability.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Frequency stability. 24.135 Section 24.135... SERVICES Narrowband PCS § 24.135 Frequency stability. (a) The frequency stability of the transmitter shall be maintained within ±0.0001 percent (±1 ppm) of the center frequency over a temperature variation...

  13. 47 CFR 24.135 - Frequency stability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Frequency stability. 24.135 Section 24.135... SERVICES Narrowband PCS § 24.135 Frequency stability. (a) The frequency stability of the transmitter shall be maintained within ±0.0001 percent (±1 ppm) of the center frequency over a temperature variation...

  14. Contour Integration across Spatial Frequency

    ERIC Educational Resources Information Center

    Persike, Malte; Olzak, Lynn A.; Meinhardt, Gunter

    2009-01-01

    Association field models of contour integration suggest that local band-pass elements are spatially grouped to global contours within limited bands of spatial frequency (Field, Hayes, & Hess, 1993). While results for local orientation and spacing variation render support for AF models, effects of spatial frequency (SF) have rarely been addressed.…

  15. Light beam frequency comb generator

    DOEpatents

    Priatko, G.J.; Kaskey, J.A.

    1992-11-24

    A light beam frequency comb generator uses an acousto-optic modulator to generate a plurality of light beams with frequencies which are uniformly separated and possess common noise and drift characteristics. A well collimated monochromatic input light beam is passed through this modulator to produce a set of both frequency shifted and unshifted optical beams. An optical system directs one or more frequency shifted beams along a path which is parallel to the path of the input light beam such that the frequency shifted beams are made incident on the modulator proximate to but separated from the point of incidence of the input light beam. After the beam is thus returned to and passed through the modulator repeatedly, a plurality of mutually parallel beams are generated which are frequency-shifted different numbers of times and possess common noise and drift characteristics. 2 figs.

  16. Light beam frequency comb generator

    DOEpatents

    Priatko, Gordon J.; Kaskey, Jeffrey A.

    1992-01-01

    A light beam frequency comb generator uses an acousto-optic modulator to generate a plurality of light beams with frequencies which are uniformly separated and possess common noise and drift characteristics. A well collimated monochromatic input light beam is passed through this modulator to produce a set of both frequency shifted and unshifted optical beams. An optical system directs one or more frequency shifted beams along a path which is parallel to the path of the input light beam such that the frequency shifted beams are made incident on the modulator proximate to but separated from the point of incidence of the input light beam. After the beam is thus returned to and passed through the modulator repeatedly, a plurality of mutually parallel beams are generated which are frequency-shifted different numbers of times and possess common noise and drift characteristics.

  17. Impulsive Injection for Compressor Stator Separation Control

    NASA Technical Reports Server (NTRS)

    Culley, Dennis E.; Braunscheidel, Edward P.; Bright, Michelle M.

    2005-01-01

    Flow control using impulsive injection from the suction surface of a stator vane has been applied in a low speed axial compressor. Impulsive injection is shown to significantly reduce separation relative to steady injection for vanes that were induced to separate by an increase in vane stagger angle of 4 degrees. Injected flow was applied to the airfoil suction surface using spanwise slots pitched in the streamwise direction. Injection was limited to the near-hub region, from 10 to 36 percent of span, to affect the dominant loss due to hub leakage flow. Actuation was provided externally using high-speed solenoid valves closely coupled to the vane tip. Variations in injected mass, frequency, and duty cycle are explored. The local corrected total pressure loss across the vane at the lower span region was reduced by over 20 percent. Additionally, low momentum fluid migrating from the hub region toward the tip was effectively suppressed resulting in an overall benefit which reduced corrected area averaged loss through the passage by 4 percent. The injection mass fraction used for impulsive actuation was typically less than 0.1 percent of the compressor through flow.

  18. Simple sweep frequency generator

    NASA Astrophysics Data System (ADS)

    Yegorov, I.

    1985-01-01

    A sweep frequency generator is described whose center frequency can be varied from 10 kHz to 50 MHz, with seven 1 to 3 and 3 to 10 scales covering the 10 kHz to 30 MHz range and one 3 to 5 scale for the 30 to 50 MHz range. It consists of a tunable pulse generator with output voltage attenuator, a diode mixer for calibration, and a sawtooth voltage generator as a source of frequency deviation. The pulse generator is a multivibrator with two emitter coupled transistors and two diodes in the collector circuit of one. The first diode extends the tuning range and increases the frequency deviation, the second diode provides the necessary base bias to the other transistor. The pulse repetition rate is modulated either directly by the sweep voltage of the calibrating oscilloscope, this voltage being applied to the base of the transistor with the two diodes in its collector circuit through an additional attenuator or a special emitter follower, or by the separate sawtooth voltage generator. The latter is a conventional two transistor multivibrator and produces signals at any constant frequency within the 40 to 60 Hz range. The mixer receives unmodulated signals from a reference frequency source and produces different frequency signals which are sent through an RCR-filter to a calibrating oscilloscope.

  19. 9 CFR 3.109 - Separation.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... unreasonable stress or discomfort or interfere with their good health. Animals housed separately must have a... isolated, information on the type and frequency of enrichment and interaction, if appropriate,...

  20. 9 CFR 3.109 - Separation.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... unreasonable stress or discomfort or interfere with their good health. Animals housed separately must have a... isolated, information on the type and frequency of enrichment and interaction, if appropriate,...

  1. Isotope separation apparatus

    DOEpatents

    Arnush, Donald; MacKenzie, Kenneth R.; Wuerker, Ralph F.

    1980-01-01

    Isotope separation apparatus consisting of a plurality of cells disposed adjacent to each other in an evacuated container. A common magnetic field is established extending through all of the cells. A source of energetic electrons at one end of the container generates electrons which pass through the cells along the magnetic field lines. Each cell includes an array of collector plates arranged in parallel or in tandem within a common magnetic field. Sets of collector plates are disposed adjacent to each other in each cell. Means are provided for differentially energizing ions of a desired isotope by applying energy at the cyclotron resonant frequency of the desired isotope. As a result, the energized desired ions are preferentially collected by the collector plates.

  2. Ferrofluid separator for nonferrous scrap separation

    NASA Technical Reports Server (NTRS)

    Kaiser, R.; Mir, L.

    1974-01-01

    Behavior of nonmagnetic objects within separator is essentially function of density, and independent of size or shape of objects. Results show close agreement between density of object and apparent density of ferrofluid required to float it. Results also demonstrate that very high separation rates are achievable by ferrofluid sink-float separation.

  3. Separability of agricultural crops with airborne scatterometry

    NASA Technical Reports Server (NTRS)

    Mehta, N. C.

    1983-01-01

    Backscattering measurements were acquired with airborne scatterometers over a site in Cass County, North Dakota on four days in the 1981 crop growing season. Data were acquired at three frequencies (L-, C- and Ku-bands), two polarizations (like and cross) and ten incidence angles (5 degrees to 50 degrees in 5 degree steps). Crop separability is studied in an hierarchical fashion. A two-class separability measure is defined, which compares within-class to between-class variability, to determine crop separability. The scatterometer channels with the best potential for crop separability are determined, based on this separability measure. Higher frequencies are more useful for discriminating small grains, while lower frequencies tend to separate non-small grains better. Some crops are more separable when row direction is taken into account. The effect of pixel purity is to increase the separability between all crops while not changing the order of useful scatterometer channels. Crude estimates of separability errors are calculated based on these analyses. These results are useful in selecting the parameters of active microwave systems in agricultural remote sensing.

  4. Challenges in the separation and analysis of scattered waves in angle-beam wavefield data

    SciTech Connect

    Dawson, Alexander J.; Michaels, Jennifer E.; Michaels, Thomas E.

    2015-03-31

    The measurement of ultrasonic signals on a 2-D rectilinear grid resulting from a fixed source, referred to as wavefield imaging, is a powerful tool for visualizing wave propagation and scattering. Wavefield imaging provides a more complete picture of wave propagation than conventional single-point measurements, but creates more challenges for analysis. This work considers the development of wavefield-based methods for analyzing angle-beam wave propagation and scattering in plates. Methods of analysis focus on the separation of scattered waves from the total wavefield with the eventual goal of quantitative scatterer characterization in a laboratory environment. Two methods for wave separation are considered: frequency-wavenumber filtering and wavefield baseline subtraction. Frequency-wavenumber filtering is applied to wavefield data that are finely sampled in both space and time, whereas baseline subtraction is a technique that has typically been applied to individual signals recorded from fixed transducers rather than to full wavefield data. Baseline subtraction of wavefields, particularly for the frequency range considered here, is sensitive to both specimen alignment and temperature variations, whereas frequency-wavenumber methods are limited in their ability to separate waves traveling in the same direction. Results are shown for both methods with a focus on investigating and overcoming the challenges to full wavefield baseline subtraction.

  5. Shoulder separation - aftercare

    MedlinePlus

    Separated shoulder - aftercare; Acromioclavicular joint separation - aftercare; A/C separation - aftercare ... slower if you have: Arthritis in your shoulder joint Damaged cartilage (cushioning tissue) between your collarbone and ...

  6. Separation Anxiety (For Parents)

    MedlinePlus

    ... 5 Things to Know About Zika & Pregnancy Separation Anxiety KidsHealth > For Parents > Separation Anxiety Print A A ... both of you get through it. How Separation Anxiety Develops Babies adapt pretty well to other caregivers. ...

  7. Theory of low frequency noise transmission through turbines

    NASA Technical Reports Server (NTRS)

    Matta, R. K.; Mani, R.

    1979-01-01

    Improvements of the existing theory of low frequency noise transmission through turbines and development of a working prediction tool are described. The existing actuator-disk model and a new finite-chord model were utilized in an analytical study. The interactive effect of adjacent blade rows, higher order spinning modes, blade-passage shocks, and duct area variations were considered separately. The improved theory was validated using the data acquired in an earlier NASA program. Computer programs incorporating the improved theory were produced for transmission loss prediction purposes. The programs were exercised parametrically and charts constructed to define approximately the low frequency noise transfer through turbines. The loss through the exhaust nozzle and flow(s) was also considered.

  8. Frequency regulator for synchronous generators

    DOEpatents

    Karlicek, R.F.

    1982-08-10

    The present invention is directed to a novel frequency regulator which controls a generator output frequency for variations in both the input power to the generator and the power supplied to an uncontrolled external load. The present invention further includes over current and current balance protection devices which are relatively inexpensive to manufacture, which may be encapsulated to provide protection from the operating environment and which respond more quickly than previously known electromechanical devices. 11 figs.

  9. Frequency regulator for synchronous generators

    DOEpatents

    Karlicek, Robert F.

    1982-01-01

    The present invention is directed to a novel frequency regulator which controls a generator output frequency for variations in both the input power to the generator and the power supplied to an uncontrolled external load. The present invention further includes over current and current balance protection devices which are relatively inexpensive to manufacture, which may be encapsulated to provide protection from the operating environment and which respond more quickly than previously known electromechanical devices.

  10. Frequency Standards and Metrology

    NASA Astrophysics Data System (ADS)

    Maleki, Lute

    2009-04-01

    Preface / Lute Maleki -- Symposium history / Jacques Vanier -- Symposium photos -- pt. I. Fundamental physics. Variation of fundamental constants from the big bang to atomic clocks: theory and observations (Invited) / V. V. Flambaum and J. C. Berengut. Alpha-dot or not: comparison of two single atom optical clocks (Invited) / T. Rosenband ... [et al.]. Variation of the fine-structure constant and laser cooling of atomic dysprosium (Invited) / N. A. Leefer ... [et al.]. Measurement of short range forces using cold atoms (Invited) / F. Pereira Dos Santos ... [et al.]. Atom interferometry experiments in fundamental physics (Invited) / S. W. Chiow ... [et al.]. Space science applications of frequency standards and metrology (Invited) / M. Tinto -- pt. II. Frequency & metrology. Quantum metrology with lattice-confined ultracold Sr atoms (Invited) / A. D. Ludlow ... [et al.]. LNE-SYRTE clock ensemble: new [symbol]Rb hyperfine frequency measurement - spectroscopy of [symbol]Hg optical clock transition (Invited) / M. Petersen ... [et al.]. Precise measurements of S-wave scattering phase shifts with a juggling atomic clock (Invited) / S. Gensemer ... [et al.]. Absolute frequency measurement of the [symbol] clock transition (Invited) / M. Chwalla ... [et al.]. The semiclassical stochastic-field/atom interaction problem (Invited) / J. Camparo. Phase and frequency noise metrology (Invited) / E. Rubiola ... [et al.]. Optical spectroscopy of atomic hydrogen for an improved determination of the Rydberg constant / J. L. Flowers ... [et al.] -- pt. III. Clock applications in space. Recent progress on the ACES mission (Invited) / L. Cacciapuoti and C. Salomon. The SAGAS mission (Invited) / P. Wolf. Small mercury microwave ion clock for navigation and radioScience (Invited) / J. D. Prestage ... [et al.]. Astro-comb: revolutionizing precision spectroscopy in astrophysics (Invited) / C. E. Kramer ... [et al.]. High frequency very long baseline interferometry: frequency standards and

  11. Time-frequency analysis: a tool to discriminate artefacts from near-field optical data.

    PubMed

    Barchiesi, D

    2001-05-01

    Near-field optical data are non-stationary, which means that their spectral content varies with the position of the tip, due to both the scanning-probe recording process and the variations of the optical signal. Therefore time-frequency representations are potentially powerful tools for local characterization as they distribute the energy of the analysed signal over the time and frequency variables, and faithfully depict the signal local behaviour. In this paper, the time-frequency distributions are shown to be appropriate tools to analyse near-field optical data by using it first on simulated data, and second on experimental near-field optical images. Within this context, we observe that time-frequency analysis allows a possible separation of relevant optical signals from artefacts, especially in the usual case where the near-field optical signal is lower band than the feedback data.

  12. Parametric study of separation and transition characteristics over an airfoil at low Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Boutilier, Michael S. H.; Yarusevych, Serhiy

    2012-06-01

    Time-resolved surface pressure measurements are used to experimentally investigate characteristics of separation and transition over a NACA 0018 airfoil for the relatively wide range of chord Reynolds numbers from 50,000 to 250,000 and angles of attack from 0° to 21°. The results provide a comprehensive data set of characteristic parameters for separated shear layer development and reveal important dependencies of these quantities on flow conditions. Mean surface pressure measurements are used to explore the variation in separation bubble position, edge velocity in the separated shear layer, and lift coefficients with angle of attack and Reynolds number. Consistent with previous studies, the separation bubble is found to move upstream and decrease in length as the Reynolds number and angle of attack increase. Above a certain angle of attack, the proximity of the separation bubble to the location of the suction peak results in a reduced lift slope compared to that observed at lower angles. Simultaneous measurements of the time-varying component of surface pressure at various spatial locations on the model are used to estimate the frequency of shear layer instability, maximum root-mean-square (RMS) surface pressure, spatial amplification rates of RMS surface pressure, and convection speeds of the pressure fluctuations in the separation bubble. A power-law correlation between the shear layer instability frequency and Reynolds number is shown to provide an order of magnitude estimate of the central frequency of disturbance amplification for various airfoil geometries at low Reynolds numbers. Maximum RMS surface pressures are found to agree with values measured in separation bubbles over geometries other than airfoils, when normalized by the dynamic pressure based on edge velocity. Spatial amplification rates in the separation bubble increase with both Reynolds number and angle of attack, causing the accompanying decrease in separation bubble length. Values of the

  13. The effect of acceleration on the growth and shedding of laminar separation bubbles

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Samik; Rival, David

    2015-11-01

    It has been observed that when a laminar boundary layer separates, the shear layer undergoes transition to turbulence and subsequently reattaches to form a laminar separation bubble (LSB). In this work, a SD7003 airfoil, held at an angle of attack of 8 degree, is towed with different acceleration profiles starting from rest. The separation region is then analyzed with time-resolved, planar PIV at short convective times during the initial acceleration phase. The aim of this work is to characterize the variation in size and shedding frequency of the laminar separation bubble with increasing acceleration. We show that the formation and shedding process in the LSB depends on the rate of vorticity-containing mass transported by the separated shear layer. Consequently, any changes in the structure of the shear layer affect the formation of the LSB downstream. Finally, attempts are also made to characterize the shedding frequency of the bubble with increasing acceleration. Here the unsteadiness of the LSB is found to be closely linked to the degree of boundary-layer acceleration on the airfoil surface.

  14. Comparison of JPL-AIRSAR and DLR E-SAR images from the MAC Europe 1991 campaign over testsite Oberpfaffenhofen: Frequency and polarization dependent backscatter variations from agricultural fields

    NASA Technical Reports Server (NTRS)

    Schmullius, C.; Nithack, J.

    1992-01-01

    On July 12, the MAC Europe '91 (Multi-Sensor Airborne Campaign) took place over test site Oberpfaffenhofen. The DLR Institute of Radio-Frequency Technology participated with its C-VV, X-VV, and X-HH Experimental Synthetic Aperture Radar (E-SAR). The high resolution E-SAR images with a pixel size between 1 and 2 m and the polarimetric AIRSAR images were analyzed. Using both sensors in combination is a unique opportunity to evaluate SAR images in a frequency range from P- to X-band and to investigate polarimetric information.

  15. Spacecraft -- Capsule Separation (Animation)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for Spacecraft -- Capsule Separation animation

    This animation shows the return capsule separating from the Stardust spacecraft.

  16. Tailoring surface properties of polyethylene separator by low pressure 13.56 MHz RF oxygen plasma glow discharge

    NASA Astrophysics Data System (ADS)

    Li, Chun; Liang, Chia-Han; Huang, Chun

    2016-01-01

    Low-pressure plasma surface modification in a radio-frequency capacitively coupled glow discharge of oxygen gas was carried out to induce polar functional groups onto polyethylene membrane separator surfaces to enhance its hydrophilicity. The surface changes in surface free energy were monitored by static contact angle measurement. A significant increase in the surface energy of polyethylene membrane separators caused by the oxygen gas plasma modifications was observed. The static water contact angle of the plasma-modified membrane separator significantly decreased with the increase in treatment duration and plasma power. An obvious increase in the surface energy of the membrane separators owing to the oxidative effect of oxygen-gas-plasma modifications was also observed. Optical emission spectroscopy was carried out to analyze the chemical species generated by oxygen gas plasma surface modification. The variations in the surface morphology and chemical structure of the separators were confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). XPS showed significantly higher surface concentrations of oxygen functional groups in the oxygen-gas-plasma-modified polymeric separator surfaces than in the unmodified polymeric separator surface. The experimental results show the important role of chemical species in the interaction between oxygen gas plasmas and the separator surface, which can be controlled by surface modification to tailor the hydrophilicity of the separator.

  17. Use of coefficient of variation in assessing variability of quantitative assays.

    PubMed

    Reed, George F; Lynn, Freyja; Meade, Bruce D

    2002-11-01

    We have derived the mathematical relationship between the coefficient of variation associated with repeated measurements from quantitative assays and the expected fraction of pairs of those measurements that differ by at least some given factor, i.e., the expected frequency of disparate results that are due to assay variability rather than true differences. Knowledge of this frequency helps determine what magnitudes of differences can be expected by chance alone when the particular coefficient of variation is in effect. This frequency is an operational index of variability in the sense that it indicates the probability of observing a particular disparity between two measurements under the assumption that they measure the same quantity. Thus the frequency or probability becomes the basis for assessing if an assay is sufficiently precise. This assessment also provides a standard for determining if two assay results for the same subject, separated by an intervention such as vaccination or infection, differ by more than expected from the variation of the assay, thus indicating an intervention effect. Data from an international collaborative study are used to illustrate the application of this proposed interpretation of the coefficient of variation, and they also provide support for the assumptions used in the mathematical derivation.

  18. Use of Coefficient of Variation in Assessing Variability of Quantitative Assays

    PubMed Central

    Reed, George F.; Lynn, Freyja; Meade, Bruce D.

    2002-01-01

    We have derived the mathematical relationship between the coefficient of variation associated with repeated measurements from quantitative assays and the expected fraction of pairs of those measurements that differ by at least some given factor, i.e., the expected frequency of disparate results that are due to assay variability rather than true differences. Knowledge of this frequency helps determine what magnitudes of differences can be expected by chance alone when the particular coefficient of variation is in effect. This frequency is an operational index of variability in the sense that it indicates the probability of observing a particular disparity between two measurements under the assumption that they measure the same quantity. Thus the frequency or probability becomes the basis for assessing if an assay is sufficiently precise. This assessment also provides a standard for determining if two assay results for the same subject, separated by an intervention such as vaccination or infection, differ by more than expected from the variation of the assay, thus indicating an intervention effect. Data from an international collaborative study are used to illustrate the application of this proposed interpretation of the coefficient of variation, and they also provide support for the assumptions used in the mathematical derivation. PMID:12414755

  19. Materials characterization using frequency domain photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Balogun, Oluwaseyi Oladeinde

    A frequency domain photoacoustic microscopy system is developed for the characterization of micro- and nanoscale materials. An amplified, intensity modulated continuous wave (CW) laser source is used to generate narrow-bandwidth acoustic waves through the thermoelastic effect. The displacement resulting from acoustic wave interaction with material boundaries is measured using a path-stabilized Michelson interferometer. The signal from the interferometer is coupled to a RF lock-in amplifier or vector network analyzer, allowing for the bandwidth of the detection system to be matched to that of the acoustic signals. Measurements are made over an extremely narrow bandwidth by modulating the excitation laser source on the sample surface over a long time interval and selecting a corresponding integration time for the detection system. An analysis of the signal-to-noise ratio (SNR) of this system indicates that it offers substantial improvements over existing systems that incorporate pulsed laser sources to generate broad bandwidth acoustic waves. Using a bandwidth of 1.0 Hz, for instance, experimental results show a minimum detectable displacement of 3.1 fm. Extracting quantitative material parameters from the complex acoustic spectrum can be difficult when multiple acoustic modes are excited, or in the presence of reflections from sample boundaries. Two techniques are used to process the measured signals. In the first technique, the modulation frequency of the excitation laser is scanned over the bandwidth of interest, and a transient sample response is constructed from the frequency domain data. Acoustic arrivals that are separated in the time domain are time gated for further analysis. In the second approach, the modulation frequency of the excitation laser is fixed, but the source to receiver distance is varied. The spatial frequencies of the acoustic modes are found by analyzing the spatial variation of the phase, allowing for the velocity of each mode generated at

  20. New limit on the present temporal variation of the fine structure constant

    SciTech Connect

    Peik, E.; Lipphardt, B.; Schnatz, H.; Schneider, T.; Tamm, Chr.; Karshenboim, S.G.

    2005-05-05

    A comparison of different atomic frequency standards over time can be used to perform a measurement of the present value of the temporal derivative of the fine structure constant {alpha} in a model-independent way without assumptions on constancy or variability of other parameters. We have measured an optical transition frequency at 688 THz in Yb+ with a cesium atomic clock at two times separated by 2.8 years and find that a variation of this frequency can be excluded within a 1{sigma} relative uncertainty of 4.4{center_dot}10-15 yr-1. Combined with recently published values for the constancy of other transition frequencies this measurement provides a limit on the present variability of {alpha} at the level of 2.0{center_dot}10-15 yr-1. Constraints are also derived for the drift rates of other fundamental constants like the electron/proton mass ratio and the proton g-factor.

  1. Variations of P2 in subpulse drifting pulsars

    NASA Astrophysics Data System (ADS)

    Yuen, R.; Melrose, D. B.; Samsuddin, M. A.; Tu, Z. Y.; Han, X. H.

    2016-06-01

    We develop a model for subpulse separation period, P2, taking into account both the apparent motion of the visible point as a function of pulsar phase, ψ, and the possibility of abrupt jumps between different rotation states in non-corotating pulsar magnetospheres. We identify three frequencies: (i) the spin frequency of the star, (ii) the drift frequency of the magnetospheric plasma in the source region and (iii) the angular frequency of the visible point around its trajectory. We show how the last of these, which is neglected in traditional models by implicitly assuming the line of sight through the centre of the star, affects the interpretation of P2. We attribute the subpulse structure to emission from m antinodes distributed uniformly in azimuthal angle about the magnetic axis. We show that variations of P2 as a function of rotational phase or observing frequency arise naturally when the motion of the visible point is taken into account. We discuss possible application of our model in signifying overall field-line distortion at the emitting region. Abrupt changes in P2 can occur during state switching in the magnetosphere. We demonstrate that the unique value of P2 in each rotation state can be used, in principle, to relate the rotation state of the magnetospheres to subpulse drifting.

  2. Coupling and tuning of modal frequencies in direct current biased microelectromechanical systems arrays

    SciTech Connect

    Kambali, Prashant N.; Swain, Gyanadutta; Pandey, Ashok Kumar; Buks, Eyal; Gottlieb, Oded

    2015-08-10

    Understanding the coupling of different modal frequencies and their tuning mechanisms has become essential to design multi-frequency MEMS devices. In this work, we fabricate a MEMS beam with fixed boundaries separated from two side electrodes and a bottom electrode. Subsequently, we perform experiments to obtain the frequency variation of in-plane and out-of-plane mechanical modes of the microbeam with respect to both DC bias and laser heating. We show that the frequencies of the two modes coincide at a certain DC bias, which in turn can also be varied due to temperature. Subsequently, we develop a theoretical model to predict the variation of the two modes and their coupling due to a variable gap between the microbeam and electrodes, initial tension, and fringing field coefficients. Finally, we discuss the influence of frequency tuning parameters in arrays of 3, 33, and 40 microbeams, respectively. It is also found that the frequency bandwidth of a microbeam array can be increased to as high as 25 kHz for a 40 microbeam array with a DC bias of 80 V.

  3. Magnetic Separation Dynamics of Colloidal Magnetic Nanoparticles

    SciTech Connect

    Kaur, M.; Huijin Zhang,; You Qiang,

    2013-01-01

    Surface functionalized magnetic nanoparticles (MNPs) are appealing candidates for analytical separation of heavy metal ions from waste water and separation of actinides from spent nuclear fuel. This work studies the separation dynamics and investigates the appropriate magnetic-field gradients. A dynamic study of colloidal MNPs was performed for steady-state flow. Measurements were conducted to record the separation time of particles as a function of magnetic field gradient. The drag and magnetic forces play a significant role on the separation time. A drop in saturation magnetization and variation of particle size occurs after surface functionalization of the MNPs; these are the primary factors that affect the separation time and velocity of the MNPs. The experimental results are correlated to a theoretical one-dimensional model.

  4. Automatic oscillator frequency control system

    NASA Technical Reports Server (NTRS)

    Smith, S. F. (Inventor)

    1985-01-01

    A frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder.

  5. Modulating action of low frequency oscillations on high frequency instabilities in Hall thrusters

    SciTech Connect

    Liqiu, Wei E-mail: weiliqiu@hit.edu.cn; Liang, Han; Ziyi, Yang; Jing, Li; Yong, Cao; Daren, Yu; Jianhua, Du

    2015-02-07

    It is found that the low frequency oscillations have modulating action on high frequency instabilities in Hall thrusters. The physical mechanism of this modulation is discussed and verified by numerical simulations. Theoretical analyses indicate that the wide-range fluctuations of plasma density and electric field associated with the low frequency oscillations affect the electron drift velocity and anomalous electron transport across the magnetic field. The amplitude and frequency of high frequency oscillations are modulated by low frequency oscillations, which show the periodic variation in the time scale of low frequency oscillations.

  6. Optimal Control of Airfoil Flow Separation using Fluidic Excitation

    NASA Astrophysics Data System (ADS)

    Shahrabi, Arireza F.

    as well as F+ were evaluated and discussed. The computational model predictions showed good agreement with the experimental data. It was observed that different angles of attack and flap angles have different requirements for the minimum value of the momentum coefficient, Cμ, in order for the SJA to be effective for control of separation. It was also found that the variation of F + noticeably affects the lift and drag forces acting on the airfoil. The optimum values of parameters during open loop control simulations have been applied in order to introduce the optimal open loop control outcome. An innovative approach has been implemented to formulate optimal frequencies and momentum ratios of vortex shedding which depends on angle of attack and static pressure of the separation zone in the upper chord. Optimal open loop results have been compared with the optimal closed loop results. Cumulative case studies in the matter of angle of attacks, flap angles, Re, Cμ and F+ provide a convincing collection of evidence to the following conclusion. An improvement of a direct closed loop control was demonstrated, and an analytical formula describing the properties of a separated flow and vortex shedding was proposed. Best AFC solutions are offered by providing optimal frequencies and momentum ratios at a variety of flow conditions.

  7. A New Device for Step-Down Inhibitory Avoidance Task—Effects of Low and High Frequency in a Novel Device for Passive Inhibitory Avoidance Task That Avoids Bioimpedance Variations

    PubMed Central

    Borba Filho, Gilvan Luiz; Zenki, Kamila Cagliari; Kalinine, Eduardo; Baggio, Suelen; Pettenuzzo, Letícia; Zimmer, Eduardo Rigon; Weis, Simone Nardin; Calcagnotto, Maria Elisa; Onofre de Souza, Diogo

    2015-01-01

    Background Step-down inhibitory avoidance task has been widely used to evaluate aversive memory, but crucial parameters inherent to traditional devices that may influence the behavior analysis (as stimulus frequency, animal’s bioimpedance) are frequently neglected. New Method We developed a new device for step-down inhibitory avoidance task by modifying the shape and distribution of the stainless steel bars in the box floor where the stimuli are applied. The bars are 2mm wide, with rectangular shape, arranged in pairs at intervals of 1cm from the next pairs. Each pair makes an electrical dipole where the polarity inverts after each pulse. This device also presents a component that acquires and records the exact current received by the animal foot and precisely controls the frequency of stimulus applied during the entire experiment. Result Different from conventional devices, this new apparatus increases the contact surface with bars and animal´s paws, allowing the electric current pass through the animal´s paws only, drastically reducing the influence of animal’s bioimpedance. The analysis of recorded data showed that the current received by the animal was practically the same as applied, independent of the animal´s body composition. Importantly, the aversive memory was observed at specific stimuli intensity and frequency (0.35 or 0.5 mA at 62 and 125Hz but not at 0.20 mA or 20 Hz). Moreover, with this device it was possible to observe the well-known step-down inhibitory avoidance task memory impairment induced by guanosine. Conclusion This new device offers a substantial improvement for behavioral analysis in step-down inhibitory avoidance task and allows us to precisely compare data from different animals with distinct body composition. PMID:25706879

  8. Self-assembly of amorphous biophotonic nanostructures by phase separation

    SciTech Connect

    Dufresne, Eric R.; Noh, Heeso; Saranathan, Vinodkumar; Mochrie, Simon G.J.; Cao, Hui; Prum, Richard O.

    2009-04-23

    Some of the most vivid colors in the animal kingdom are created not by pigments, but by wavelength-selective scattering of light from nanostructures. Here we investigate quasi-ordered nanostructures of avian feather barbs which produce vivid non-iridescent colors. These {beta}-keratin and air nanostructures are found in two basic morphologies: tortuous channels and amorphous packings of spheres. Each class of nanostructure is isotropic and has a pronounced characteristic length scale of variation in composition. These local structural correlations lead to strong backscattering over a narrow range of optical frequencies and little variation with angle of incidence. Such optical properties play important roles in social and sexual communication. To be effective, birds need to precisely control the development of these nanoscale structures, yet little is known about how they grow. We hypothesize that multiple lineages of birds have convergently evolved to exploit phase separation and kinetic arrest to self-assemble spongy color-producing nanostructures in feather barbs. Observed avian nanostructures are strikingly similar to those self-assembled during the phase separation of fluid mixtures; the channel and sphere morphologies are characteristic of phase separation by spinodal decomposition and nucleation and growth, respectively. These unstable structures are locked-in by the kinetic arrest of the {beta}-keratin matrix, likely through the entanglement or cross-linking of supermolecular {beta}-keratin fibers. Using the power of self-assembly, birds can robustly realize a diverse range of nanoscopic morphologies with relatively small physical and chemical changes during feather development.

  9. Frequency Standards and Metrology

    NASA Astrophysics Data System (ADS)

    Maleki, Lute

    2009-04-01

    Preface / Lute Maleki -- Symposium history / Jacques Vanier -- Symposium photos -- pt. I. Fundamental physics. Variation of fundamental constants from the big bang to atomic clocks: theory and observations (Invited) / V. V. Flambaum and J. C. Berengut. Alpha-dot or not: comparison of two single atom optical clocks (Invited) / T. Rosenband ... [et al.]. Variation of the fine-structure constant and laser cooling of atomic dysprosium (Invited) / N. A. Leefer ... [et al.]. Measurement of short range forces using cold atoms (Invited) / F. Pereira Dos Santos ... [et al.]. Atom interferometry experiments in fundamental physics (Invited) / S. W. Chiow ... [et al.]. Space science applications of frequency standards and metrology (Invited) / M. Tinto -- pt. II. Frequency & metrology. Quantum metrology with lattice-confined ultracold Sr atoms (Invited) / A. D. Ludlow ... [et al.]. LNE-SYRTE clock ensemble: new [symbol]Rb hyperfine frequency measurement - spectroscopy of [symbol]Hg optical clock transition (Invited) / M. Petersen ... [et al.]. Precise measurements of S-wave scattering phase shifts with a juggling atomic clock (Invited) / S. Gensemer ... [et al.]. Absolute frequency measurement of the [symbol] clock transition (Invited) / M. Chwalla ... [et al.]. The semiclassical stochastic-field/atom interaction problem (Invited) / J. Camparo. Phase and frequency noise metrology (Invited) / E. Rubiola ... [et al.]. Optical spectroscopy of atomic hydrogen for an improved determination of the Rydberg constant / J. L. Flowers ... [et al.] -- pt. III. Clock applications in space. Recent progress on the ACES mission (Invited) / L. Cacciapuoti and C. Salomon. The SAGAS mission (Invited) / P. Wolf. Small mercury microwave ion clock for navigation and radioScience (Invited) / J. D. Prestage ... [et al.]. Astro-comb: revolutionizing precision spectroscopy in astrophysics (Invited) / C. E. Kramer ... [et al.]. High frequency very long baseline interferometry: frequency standards and

  10. 47 CFR 76.612 - Cable television frequency separation standards.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., the radionavigation glide path channels are listed in Section 87.501 of the Rules. Note: The HRC system, as described above, will meet this requirement in the 328.6-335.4 MHz navigation glide path band... glide path band....

  11. Nonlinear dynamics of a thin liquid film on an axially oscillating cylindrical surface subjected to double-frequency forcing.

    PubMed

    Haimovich, Ory; Oron, Alexander

    2013-05-01

    The nonlinear dynamics of a thin axisymmetric liquid film on a horizontal cylindrical substrate subjected to an axial double-frequency forcing that consists of two components of different amplitudes and frequencies and a possible phase shift is considered in this paper. A nonlinear evolution equation governing the spatiotemporal dynamics of the film interface has been derived in the long-wave limit. Similar to the case of a single-frequency forcing considered in our earlier work, there exists a critical forcing amplitude below which the film undergoes a long-time capillary rupture typical for a static cylinder, whereas above it the film remains continuous. We find that it is possible to arrest the rupture even if the forcing parameters of each of the two components correspond separately to the domain where rupture takes place. It is shown that the critical forcing amplitude is easily determined via a single-frequency case when the two forcing frequencies are equal. In the case of different forcing amplitudes and frequencies, the variation of the critical forcing amplitude as a function of the frequency ratio exhibits a unique behavior displaying the emergence of spikes. A related case of an amplitude-modulated single-frequency forcing is also addressed here. For a sufficiently small frequency of the amplitude modulation, a significant increase of the pattern amplitude is observed. In the case of commensurate forcing frequencies, the flow is found to be quasiperiodic. PMID:23767550

  12. Grace DAKASEP alkaline battery separator

    NASA Technical Reports Server (NTRS)

    Giovannoni, R. T.; Lundquist, J. T.; Choi, W. M.

    1987-01-01

    The Grace DAKASEP separator was originally developed as a wicking layer for nickel-zinc alkaline batteries. The DAKASEP is a filled non-woven separator which is flexible and heat sealable. Through modification of formulation and processing variables, products with a variety of properties can be produced. Variations of DAKASEP were tested in Ni-H2, Ni-Zn, Ni-Cd, and primary alkaline batteries with good results. The properties of DAKASEP which are optimized for Hg-Zn primary batteries are shown in tabular form. This separator has high tensile strength, 12 micron average pore size, relatively low porosity at 46-48 percent, and consequently moderately high resistivity. Versions were produced with greater than 70 percent porosity and resistivities in 33 wt percent KOH as low as 3 ohm cm. Performance data for Hg-Zn E-1 size cells containing DAKASEP with the properties shown in tabular form, are more reproducible than data obtained with a competitive polypropylene non-woven separator. In addition, utilization of active material is in general considerably improved.

  13. Vapors-liquid phase separator

    NASA Astrophysics Data System (ADS)

    Frederking, T. H. K.; Brown, G. S.; Chuang, C.; Kamioka, Y.; Kim, Y. I.; Lee, J. M.; Yuan, S. W. K.

    1980-10-01

    The use of porous plugs, mostly with in the form of passive devices with constant area were considered as vapor-liquid phase separators for helium 2 storage vessels under reduced gravity. The incorporation of components with variable cross sectional area as a method of flow rate modification was also investigated. A particular device which uses a shutter-type system for area variation was designed and constructed. This system successfully permitted flor rate changes of up to plus or minus 60% from its mean value.

  14. Low-Frequency Electromagnetic Sounding for Planetary Volatiles (Invited)

    NASA Astrophysics Data System (ADS)

    Grimm, R. E.

    2013-12-01

    EM sounding is divided by loss tangent << 1 (surface-penetrating radars) and >> 1 (inductive methods). The former have high resolution and responses dominated by dielectric permittivity. They have been useful for sounding the polar caps of Mars and are very promising to image the shells of icy satellites as well as the uppermost crusts of silicate bodies. The latter have poorer resolution but greater penetration depth, responses dominated by electrical conductivity, and are the subject of this talk. Low-frequency inductive methods are further divided by comparing the source-receiver separation to the skin depth. Large separations are parametric in frequency so that the variation of EM response with frequency is translated to change in conductivity with depth. Parametric soundings can exploit natural sources from the solar wind, magnetosphere, ionosphere, or atmosphere. Small source-sensor separations are geometric with transmitter-receiver positions: both conductivity and permittivity can be recovered as a function of frequency (a dielectric spectrum), but at greater resource requirements. Subsurface liquid water is an optimal low-frequency EM target because even small quantities of dissolved ions make it a powerful electrical conductor compared to dry, resistive, silicate crusts. Water at kms or even tens of kms can be detected using the magnetotelluric, geomagnetic-depth sounding, or wave-tilt methods: these are all natural-source soundings using different combinations of field components and receiver geometries. If natural sources are weak or absent, a transmitter can be used to obtain high SNR; the time-domain EM (TDEM) method has been used extensively for terrestrial groundwater exploration. Using a ballistically deployed 200-m diameter transmitter loop, TDEM can detect groundwater at depths of several km. If landed in a region of strong local crustal magnetism, the characteristic Larmor frequency of liquid water can be detected with a TDEM-like setup using

  15. Chaotic attractors with separated scrolls

    NASA Astrophysics Data System (ADS)

    Bouallegue, Kais

    2015-07-01

    This paper proposes a new behavior of chaotic attractors with separated scrolls while combining Julia's process with Chua's attractor and Lorenz's attractor. The main motivation of this work is the ability to generate a set of separated scrolls with different behaviors, which in turn allows us to choose one or many scrolls combined with modulation (amplitude and frequency) for secure communication or synchronization. This set seems a new class of hyperchaos because each element of this set looks like a simple chaotic attractor with one positive Lyapunov exponent, so the cardinal of this set is greater than one. This new approach could be used to generate more general higher-dimensional hyperchaotic attractor for more potential application. Numerical simulations are given to show the effectiveness of the proposed theoretical results.

  16. Chaotic attractors with separated scrolls

    SciTech Connect

    Bouallegue, Kais

    2015-07-15

    This paper proposes a new behavior of chaotic attractors with separated scrolls while combining Julia's process with Chua's attractor and Lorenz's attractor. The main motivation of this work is the ability to generate a set of separated scrolls with different behaviors, which in turn allows us to choose one or many scrolls combined with modulation (amplitude and frequency) for secure communication or synchronization. This set seems a new class of hyperchaos because each element of this set looks like a simple chaotic attractor with one positive Lyapunov exponent, so the cardinal of this set is greater than one. This new approach could be used to generate more general higher-dimensional hyperchaotic attractor for more potential application. Numerical simulations are given to show the effectiveness of the proposed theoretical results.

  17. Magnetic separation of algae

    DOEpatents

    Nath, Pulak; Twary, Scott N.

    2016-04-26

    Described herein are methods and systems for harvesting, collecting, separating and/or dewatering algae using iron based salts combined with a magnetic field gradient to separate algae from an aqueous solution.

  18. Imaging dielectric relaxation in nanostructured polymers by frequency modulation electrostatic force microscopy

    NASA Astrophysics Data System (ADS)

    Riedel, C.; Sweeney, R.; Israeloff, N. E.; Arinero, R.; Schwartz, G. A.; Alegria, A.; Tordjeman, Ph.; Colmenero, J.

    2010-05-01

    We have developed a method for imaging the temperature-frequency dependence of the dynamics of nanostructured polymer films with spatial resolution. This method provides images with dielectric compositional contrast well decoupled from topography. Using frequency-modulation electrostatic-force-microscopy, we probe the local frequency-dependent (0.1-100 Hz) dielectric response through measurement of the amplitude and phase of the force gradient in response to an oscillating applied electric field. When the phase is imaged at fixed frequency, it reveals the spatial variation in dielectric losses, i.e., the spatial variation in molecular/dipolar dynamics, with 40 nm lateral resolution. This is demonstrated by using as a model system; a phase separated polystyrene/polyvinyl-acetate (PVAc) blend. We show that nanoscale dynamic domains of PVAc are clearly identifiable in phase images as those which light-up in a band of temperature, reflecting the variations in the molecular/dipolar dynamics approaching the glass transition temperature of PVAc.

  19. Method for isotope separation by photodeflection

    DOEpatents

    Bernhardt, Anthony F.

    1977-01-01

    In the method of separating isotopes wherein a desired isotope species is selectively deflected out of a beam of mixed isotopes by irradiating the beam with a directed beam of light of narrowly defined frequency which is selectively absorbed by the desired species, the improvement comprising irradiating the deflected beam with light from other light sources whose frequencies are selected to cause the depopulation of any metastable excited states.

  20. Atmospheric electric field variations and lower ionosphere disturbance during the total solar eclipse of 2010 July 11

    NASA Astrophysics Data System (ADS)

    Tacza, José C.; Raulin, Jean-Pierre; Macotela, Edith L.; Norabuena, Edmundo O.; Fernandez, Germán

    2016-11-01

    In this paper, we study the variations of atmospheric electric field during the total solar eclipse (TSE) of July 11, 2010, at Complejo Astronómico El Leoncito (CASLEO). These variations observed with two identical sensors separated by 0.4 km, show a significant increase (∼55 V/m) when compared with averaged values measured during previous and subsequent fair weather days. Furthermore, identical changes are detected on the measured phases of Very Low Frequency waves received at CASLEO. The latter suggests a possible connection between the lower ionosphere and the lower atmosphere during the period of the eclipse.

  1. Separation in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Facemire, B. R.; Kaukler, W. F.; Witherow, W. K.; Fanning, U.

    1986-01-01

    Studies of monotectic alloys and alloy analogs reviewed. Report surveys research on liquid/liquid and solid/liquid separation in binary monotectic alloys. Emphasizes separation processes in low gravity, such as in outer space or in free fall in drop towers. Advances in methods of controlling separation in experiments highlighted.

  2. Meniscus Membranes For Separation

    DOEpatents

    Dye, Robert C.; Jorgensen, Betty; Pesiri, David R.

    2005-09-20

    Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

  3. Space shuttle separation mechanisms

    NASA Technical Reports Server (NTRS)

    Rogers, W. F.

    1978-01-01

    The development of space shuttle separation devices is reviewed to illustrate the mechanisms involved in separating the Orbiter from the Boeing 747 carrier aircraft and from the externally mounted propellant tank. Other aspects of the separation device development discussed include design evolution, operational experience during the orbiter approach and landing tests, and the work required to produce an operational system.

  4. Space Shuttle separation mechanisms

    NASA Technical Reports Server (NTRS)

    Rogers, W. F.

    1979-01-01

    The development of space shuttle separation devices is reviewed to illustrate the mechanisms involved in separating the orbiter from the Boeing 747 carrier aircraft and from the externally mounted propellant tank. Other aspects of the separation device development discussed include design evolution, operational experience during the orbiter approach and landing tests, and the work to be accomplished before an operational system becomes a reality.

  5. Meniscus membranes for separations

    DOEpatents

    Dye, Robert C.; Jorgensen, Betty; Pesiri, David R.

    2004-01-27

    Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

  6. A variable-frequency local oscillator for the frequency-hopping technique

    NASA Technical Reports Server (NTRS)

    Stitt, G. R.; Johnson, L. J.

    1986-01-01

    The frequency hopping technique described elsewhere requires the use of a local oscillator whose output frequency may be rapidly and accurately changed by a fixed frequency increment. Such a device, capable of producing 16 different frequencies separated by 50 kHz over the range of 35.02 to 35.77 MHz, has been built for the Urbana MST (mesosphere stratosphere troposphere) radar facility. The design and construction of that device is described and illustrated.

  7. Safety shutdown separators

    SciTech Connect

    Carlson, Steven Allen; Anakor, Ifenna Kingsley; Farrell, Greg Robert

    2015-06-30

    The present invention pertains to electrochemical cells which comprise (a) an anode; (b) a cathode; (c) a solid porous separator, such as a polyolefin, xerogel, or inorganic oxide separator; and (d) a nonaqueous electrolyte, wherein the separator comprises a porous membrane having a microporous coating comprising polymer particles which have not coalesced to form a continuous film. This microporous coating on the separator acts as a safety shutdown layer that rapidly increases the internal resistivity and shuts the cell down upon heating to an elevated temperature, such as 110.degree. C. Also provided are methods for increasing the safety of an electrochemical cell by utilizing such separators with a safety shutdown layer.

  8. Separating Pumping and Other Influences on Groundwater Head Variation

    NASA Astrophysics Data System (ADS)

    Shapoori, V.; Western, A. W.; Peterson, T. J.; Costelloe, J.

    2012-12-01

    The dynamics of unconfined groundwater levels are usually the result of numerous and interacting factors, such as land cover change, climate variability and groundwater pumping. Estimating the impact from pumping is highly significant for resource management but also very challenging. A variety of methods are used to model water-table dynamics influenced by pumping, ranging from spatially explicit, numerical models to stochastic approaches. Transfer function noise (TFN) modelling can be used to model the dynamic behaviour of a wide range of hydrologic variables, including time series of groundwater head. Recently, TFN models have been developed to better link water table dynamics with different types of individual stresses, including pumping (Von Asmuth et al. 2002). Peterson & Western (2011) advanced the transfer function noise model of Von Asmuth et al. (2002) to account for non-linear hydrological processes by inclusion of a parsimonious vertically lumped soil moisture storage(SMS). Shapoori et al. (2011) proposed an improved time series formulation for estimation of the impacts of pumping. That study undertook a synthetic assessment of the ability of a range of time series models to represent the impacts of pumping by applying them to groundwater head time series from a synthetic aquifer. This paper further expands the Shapoori at al. (2011) time series method for quantifying the impact of groundwater pumping within unconfined sedimentary aquifers by applying it to real data and by taking account of a surface water body. The study area is the Clydebank groundwater subregion located in Victoria Australia. Nine salinity control pumping bores are used in some of the worst salinity areas to lower the groundwater table and consequently reduce soil salinity. The method has been applied to 43 observation bores and the results show that the model has good predictive performance with mean and minimum coefficient efficiency values of 0.7 and 0.5 respectively. In addition to estimating the pumping effect on head, preliminary work indicates that the volume of extraction from the surface body due to pumping and the transmissivity and storativity of the aquifer can be estimated. The latter are very consistent with pumping test results. This method could efficiently provide important information for management of coupled surface-groundwater systems and for characterising aquifer properties from observation and pumping data only. Moreover, the time series parameters have a reasonable spatial correlation. Future work will use this to develop multi-site groundwater time series methods. Reference Peterson ,T.J. and Western A.W.(2011). Time-series modelling of groundwater head and its de-composition to historic climate periods, 34th IAHR World Congress, Brisbane, Australia Shapoori, V., T. J. Peterson , A. W. Western and J. Costelloe (2011). Quantifying the impact of pumping on groundwater heads using observation data and advanced time series analysis. International Congress On Modelling and Simulation (MODSIM) Perth, Australia Von asmuth, J. R., Bierkens, M. F. P. and Maas, K.(2002). Transfer function-noise modeling in continuous time using predefined impulse reponse functions, Water Resources Research 46(1), 30-40

  9. Operating Frequencies for Educational Satellite Services.

    ERIC Educational Resources Information Center

    Singh, Jai P.

    Part of a continuing study of application of communication satellites for helping to meet educational needs, this memorandum discusses operating frequencies for educational satellite services. Each of the factors affecting choice of transmission frequencies is identified and discussed in a separate section. Included among these factors are…

  10. Transform domain steganography with blind source separation

    NASA Astrophysics Data System (ADS)

    Jouny, Ismail

    2015-05-01

    This paper applies blind source separation or independent component analysis for images that may contain mixtures of text, audio, or other images for steganography purposes. The paper focuses on separating mixtures in the transform domain such as Fourier domain or the Wavelet domain. The study addresses the effectiveness of steganography when using linear mixtures of multimedia components and the ability of standard blind sources separation techniques to discern hidden multimedia messages. Mixing in the space, frequency, and wavelet (scale) domains is compared. Effectiveness is measured using mean square error rate between original and recovered images.

  11. Low-frequency magnetic fluctuation spectra in the magnetosheath and plasma depletion layer

    NASA Technical Reports Server (NTRS)

    Denton, Richard E.; Gary, S. Peter; Anderson, Brian J.; Fuselier, Stephen A.; Hudson, Mary K.

    1994-01-01

    Recent observations have delineated several different kinds of enhanced magnetic fluctuation spectra below the proton cyclotron frequency in the terrestrial magnetosheath. A model is presented that represents the variation of plasma parameters across the plasma depletion layer and into the magnetosheath proper. Using this model, we find that many of the properties of the observed spectra follow directly from the predictions of linear Vlasov instability theory. The observed progression of spectral features is a natural progression from mirror mode to merged (in frequency range) proton and He(2+) cyclotron modes to bifurcated (in frequency range) cyclotron modes as plasma convects earthward in the magnetosheath. The necessary change in dispersion surface topology from separated proton and He(2+) cyclotron surfaces at low beta to merged surfaces at high beta is described.

  12. Assessing the value of multi-receiver low-frequency electromagnetic-induction (EMI) measurement for assessing variation in soil moisture content in field experiments with winter wheat (Triticum aestivum)

    NASA Astrophysics Data System (ADS)

    Shanahan, Peter; Binley, Andrew; Dodd, Ian; Whalley, Richard; Watts, Chris; Ashton, Rhys; Ober, Eric

    2014-05-01

    In large plant breeding field trials with multiple genotypes, measuring soil water status (an indicator of crop water uptake) by conventional techniques (e.g. core extraction and penetration resistance) is limited by the cost and effort needed to achieve sufficient replication to apply robust statistical analysis. Geophysical methods may provide a more cost-effective means of more assessing valuable information about soil water status for such studies. We present here results from a field experiment using geophysical techniques for remote mapping of soil water content on sandy loam and silt loam soils in spring/summer 2013 in the UK. The aim of the study was to assess electromagnetic-induction (EMI) conductivity measurements for sensitivity to variations in shallow soil electrical properties and the spatial and temporal mapping of soil water. The CMD Mini-Explorer (GF Instruments) operates with three receiver coils at fixed distances from a transmitter coil (0.32 m, 0.71 m, 1.2 m). Measurement of magnetic field quadrature in horizontal coplanar (HC) and vertical coplanar (VC) of the three receiver coils provides six depths of investigation for the given coil spacing cumulative sensitivities. At the two field sites the instrument was applied to measuring apparent electrical conductivity (ECa) below 7.0 x 1.8 m plots consisting of 23 rain fed winter wheat cultivars and bare soil fallow control plots. These plots were sown in March 2013 and organised into a randomised block design. Electrical resistivity tomography (ERT) surveys along 15 m transects were also conducted at the two sites in order to compare EMI measured ECa. Our results show that progressive soil drying at both sites due to crop uptake significantly decreased (p<0.05) soil ECa. The difference in soil ECa as a result of water uptake between cultivars was found to be significant (p<0.05) from one of the coil configurations (coil spacing 1.8m in HC mode), and only at the silty loam site (no significant

  13. Aptamers in Affinity Separations: Stationary Separation

    NASA Astrophysics Data System (ADS)

    Ravelet, Corinne; Peyrin, Eric

    The use of DNA or RNA aptamers as tools in analytical chemistry is a very promising field of research because of their capabilities to bind specifically the target molecules with an affinity similar to that of antibodies. Notably, they appear to be of great interest as target-specific ligands for the separation and capture of various analytes in affinity chromatography and related affinity-based methods such as magnetic bead technology. In this chapter, the recent developments of these aptamer-based separation/capture approaches are addressed.

  14. Isotope separation by photochromatography

    DOEpatents

    Suslick, K.S.

    1975-10-03

    A photochromatographic method for isotope separation is described. An isotopically mixed molecular species is adsorbed on an adsorptive surface, and the adsorbed molecules are irradiated with radiation of a predetermined wavelength which will selectively excite desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thus separate them from the undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes. (BLM)

  15. [Separation anxiety. Theoretical considerations].

    PubMed

    Blandin, N; Parquet, P J; Bailly, D

    1994-01-01

    The interest in separation anxiety is nowadays increasing: this disorder appearing during childhood may predispose to the occurrence of anxiety disorders (such as panic disorder and agoraphobia) and major depression into adulthood. Psychoanalytic theories differ on the nature of separation anxiety and its place in child development. For some authors, separation anxiety must be understood as resulting from the unconscious internal conflicts inherent in the individuation process and gradual attainment of autonomy. From this point of view, the fear of loss of mother by separation is not regarded as resulting from a real danger. However, Freud considers the primary experience of separation from protecting mother as the prototype situation of anxiety and compares the situations generating fear to separation experiences. For him, anxiety originates from two factors: the physiological fact is initiated at the time of birth but the primary traumatic situation is the separation from mother. This point of view may be compared with behavioral theories. Behavioral theories suggest that separation anxiety may be conditioned or learned from innate fears. In Freud's theory, the primary situation of anxiety resulting from the separation from mother plays a role comparable to innate fears. Grappling with the problem of separation anxiety, Bowlby emphasizes then the importance of the child's attachment to one person (mother or primary caregiver) and the fact that this attachment is instinctive. This point of view, based on the watch of infants, is akin to ethological theories on behaviour of non human primates. Bowlby especially shows that the reactions of infant separated from mother evolve on three stages: the phase of protestation which may constitute the prototype of adulthood anxiety, the phase of desperation which may be the prototype of depression, and the phase of detachment. He emphasizes so the role of early separations in the development of vulnerability to depression

  16. Isotope separation by photochromatography

    DOEpatents

    Suslick, Kenneth S.

    1977-01-01

    An isotope separation method which comprises physically adsorbing an isotopically mixed molecular species on an adsorptive surface and irradiating the adsorbed molecules with radiation of a predetermined wavelength which will selectively excite a desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thereby separate them from the unexcited undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes.

  17. The ADvanced SEParation (ADSEP)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The ADvanced SEParation (ADSEP) commercial payload is making use of major advances in separation technology: The Phase Partitioning Experiment (PPE); the Micorencapsulation experiment; and the Hemoglobin Separation Experiment (HSE). Using ADSEP, commercial researchers will attempt to determine the partition coefficients for model particles in a two-phase system. With this information, researchers can develop a higher resolution, more effective cell isolation procedure that can be used for many different types of research and for improved health care. The advanced separation technology is already being made available for use in ground-based laboratories.

  18. Pressure levels and pulsation frequencies can be varied on high pressure/frequency testing device

    NASA Technical Reports Server (NTRS)

    Routson, J. W.

    1967-01-01

    Hydraulic system components test device obtains a pulsating pressure from a hydraulic actuator that is being driven by a vibration exciter of sufficient force and displacement. Input to the exciter controls the frequency of pressure variation.

  19. Kinetics of microphase separation in interpenetrated polymer networks in solution.

    PubMed

    Derouiche, A; Benhamou, M; Bettachy, A

    2005-04-01

    We present here a theoretical study of the early kinetics of the microphase separation in crosslinked polymer blends, made of two incompatible polymers A and B, dissolved in a common good solvent. Use is made of an extended blob model used previously for the investigation of the static properties of such a transition. We are interested in the variation of the relaxation rate, tau(q), versus the wave number q, in the vicinity of the spinodal temperature. We first show that kinetics is entirely dominated by local motions, which are of Rouse type. Slow motions are absent, because of the permanent presence of crosslinks. Second, we find that the characteristic frequency, omega (q) = tau(q)(-1), increases with increasing wave number q according to a sixth power law, that is omega (q) approximately q6 phi(-9/4), where phi is the overall monomer volume fraction. Therefore, the swelling of strands due to the excluded-volume forces leads to a renormalization of the characteristic frequency by a multiplicative factor scaling as phi(-9/4). The main conclusion is that the presence of a good solvent necessitates relaxation rates less important than those relative to crosslinked mixtures in the molten state.

  20. The separation of adult separation anxiety disorder.

    PubMed

    Baldwin, David S; Gordon, Robert; Abelli, Marianna; Pini, Stefano

    2016-08-01

    The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) categorization of mental disorders places "separation anxiety disorder" within the broad group of anxiety disorders, and its diagnosis no longer rests on establishing an onset during childhood or adolescence. In previous editions of DSM, it was included within the disorders usually first diagnosed in infancy, childhood, or adolescence, with the requirement for an onset of symptoms before the age of 18 years: symptomatic adults could only receive a retrospective diagnosis, based on establishing this early onset. The new position of separation anxiety disorder is based upon the findings of epidemiological studies that revealed the unexpectedly high prevalence of the condition in adults, often in individuals with an onset of symptoms after the teenage years; its prominent place within the DSM-5 group of anxiety disorders should encourage further research into its epidemiology, etiology, and treatment. This review examines the clinical features and boundaries of the condition, and offers guidance on how it can be distinguished from other anxiety disorders and other mental disorders in which "separation anxiety" may be apparent.

  1. The separation of adult separation anxiety disorder.

    PubMed

    Baldwin, David S; Gordon, Robert; Abelli, Marianna; Pini, Stefano

    2016-08-01

    The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) categorization of mental disorders places "separation anxiety disorder" within the broad group of anxiety disorders, and its diagnosis no longer rests on establishing an onset during childhood or adolescence. In previous editions of DSM, it was included within the disorders usually first diagnosed in infancy, childhood, or adolescence, with the requirement for an onset of symptoms before the age of 18 years: symptomatic adults could only receive a retrospective diagnosis, based on establishing this early onset. The new position of separation anxiety disorder is based upon the findings of epidemiological studies that revealed the unexpectedly high prevalence of the condition in adults, often in individuals with an onset of symptoms after the teenage years; its prominent place within the DSM-5 group of anxiety disorders should encourage further research into its epidemiology, etiology, and treatment. This review examines the clinical features and boundaries of the condition, and offers guidance on how it can be distinguished from other anxiety disorders and other mental disorders in which "separation anxiety" may be apparent. PMID:27503572

  2. HILIC separation mechanisms of tetracyclines on amino bonded silica column

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of mobile phase variations on the chromatographic separation on amino bonded silica column in hydrophilic interaction chromatography (HILIC) were investigated for four zwitterionic tetracyclines (TCs): oxytetracycline, doxycycline, chlortetracycline and tetracycline. A mixed-mode retention m...

  3. Social Separation in Monkeys.

    ERIC Educational Resources Information Center

    Mineka, Susan; Suomi, Stephen J.

    1978-01-01

    Reviews phenomena associated with social separation from attachment objects in nonhuman primates. Evaluates four theoretical treatments of separation in light of existing data: Bowlby's attachment-object-loss theory, Kaufman's conservation-withdrawal theory, Seligman's learned helplessness theory, and Solomon and Corbit's opponent-process theory.…

  4. Fragment Separator ACCULINNA-2

    SciTech Connect

    Krupko, S. A.; Fomichev, A. S.; Chudoba, V.; Daniel, A. V.; Golovkov, M. S.; Gorshkov, V. A.; Oganessian, Yu. Ts.; Sidorchuk, S. I.; Slepnev, R. S.; Stepantsov, S. V.; Ter-Akopian, G. M.; Wolski, R.; Grigorenko, L. V.; Tarasov, O. B.; Ershov, S. N.; Lukyanov, V. K.; Danilin, B. V.; Korsheninnikov, A. A.; Goldberg, V. Z.; Mukha, I. G.

    2010-04-30

    Project of a new in-flight fragment separator is proposed as a part of the third generation DRIBs facilities in Dubna. As compared to the existing separator ACCULINNA, beam intensity should be increased by a factor 10-15, the beam quality improved and the RIB assortment should broaden considerably at ACCULINNA-2. Research program and structure are outlined for the new instrument.

  5. Method for separating isotopes

    DOEpatents

    Jepson, B.E.

    1975-10-21

    Isotopes are separated by contacting a feed solution containing the isotopes with a cyclic polyether wherein a complex of one isotope is formed with the cyclic polyether, the cyclic polyether complex is extracted from the feed solution, and the isotope is thereafter separated from the cyclic polyether.

  6. Separators for flywheel rotors

    DOEpatents

    Bender, D.A.; Kuklo, T.C.

    1998-07-07

    A separator forms a connection between the rotors of a concentric rotor assembly. This separator allows for the relatively free expansion of outer rotors away from inner rotors while providing a connection between the rotors that is strong enough to prevent disassembly. The rotor assembly includes at least two rotors referred to as inner and outer flywheel rings or rotors. This combination of inner flywheel ring, separator, and outer flywheel ring may be nested to include an arbitrary number of concentric rings. The separator may be a segmented or continuous ring that abuts the ends of the inner rotor and the inner bore of the outer rotor. It is supported against centrifugal loads by the outer rotor and is affixed to the outer rotor. The separator is allowed to slide with respect to the inner rotor. It is made of a material that has a modulus of elasticity that is lower than that of the rotors. 10 figs.

  7. Substituted polyacetylene separation membrane

    DOEpatents

    Pinnau, I.; Morisato, Atsushi

    1998-01-13

    A separation membrane is described which is useful for gas separation, particularly separation of C{sub 2+} hydrocarbons from natural gas. The invention encompasses the membrane itself, methods of making it and processes for using it. The membrane comprises a polymer having repeating units of a hydrocarbon-based, disubstituted polyacetylene, having the general formula shown in the accompanying diagram, wherein R{sub 1} is chosen from the group consisting of C{sub 1}-C{sub 4} alkyl and phenyl, and wherein R{sub 2} is chosen from the group consisting of hydrogen and phenyl. In the most preferred embodiment, the membrane comprises poly(4-methyl-2-pentyne) [PMP]. The membrane exhibits good chemical resistance and has super-glassy properties with regard to separating certain large, condensable permeant species from smaller, less-condensable permeant species. The membranes may also be useful in other fluid separations. 4 figs.

  8. Substituted polyacetylene separation membrane

    DOEpatents

    Pinnau, Ingo; Morisato, Atsushi

    1998-01-13

    A separation membrane useful for gas separation, particularly separation of C.sub.2+ hydrocarbons from natural gas. The invention encompasses the membrane itself, methods of making it and processes for using it. The membrane comprises a polymer having repeating units of a hydrocarbon-based, disubstituted polyacetylene, having the general formula: ##STR1## wherein R.sub.1 is chosen from the group consisting of C.sub.1 -C.sub.4 alkyl and phenyl, and wherein R.sub.2 is chosen from the group consisting of hydrogen and phenyl. In the most preferred embodiment, the membrane comprises poly(4-methyl-2-pentyne) ›PMP!. The membrane exhibits good chemical resistance and has super-glassy properties with regard to separating certain large, condensable permeant species from smaller, less-condensable permeant species. The membranes may also be useful in other fluid separations.

  9. Separators for flywheel rotors

    DOEpatents

    Bender, Donald A.; Kuklo, Thomas C.

    1998-01-01

    A separator forms a connection between the rotors of a concentric rotor assembly. This separator allows for the relatively free expansion of outer rotors away from inner rotors while providing a connection between the rotors that is strong enough to prevent disassembly. The rotor assembly includes at least two rotors referred to as inner and outer flywheel rings or rotors. This combination of inner flywheel ring, separator, and outer flywheel ring may be nested to include an arbitrary number of concentric rings. The separator may be a segmented or continuous ring that abuts the ends of the inner rotor and the inner bore of the outer rotor. It is supported against centrifugal loads by the outer rotor and is affixed to the outer rotor. The separator is allowed to slide with respect to the inner rotor. It is made of a material that has a modulus of elasticity that is lower than that of the rotors.

  10. Isothermal separation processes

    NASA Technical Reports Server (NTRS)

    England, C.

    1982-01-01

    The isothermal processes of membrane separation, supercritical extraction and chromatography were examined using availability analysis. The general approach was to derive equations that identified where energy is consumed in these processes and how they compare with conventional separation methods. These separation methods are characterized by pure work inputs, chiefly in the form of a pressure drop which supplies the required energy. Equations were derived for the energy requirement in terms of regular solution theory. This approach is believed to accurately predict the work of separation in terms of the heat of solution and the entropy of mixing. It can form the basis of a convenient calculation method for optimizing membrane and solvent properties for particular applications. Calculations were made on the energy requirements for a membrane process separating air into its components.

  11. Can accelerometers detect mass variations in Amazonian trees?

    NASA Astrophysics Data System (ADS)

    van Emmerik, Tim; Steele-Dunne, Susan; Gentine, Pierre; Guerin, Marceau; Hut, Rolf; Oliveira, Rafael; van de Giesen, Nick

    2016-04-01

    The mass of trees is influenced by physiological processes within the tree (e.g. transpiration and root water uptake), as well as external loads (e.g. intercepted precipitation). Recent studies have found diurnal variations in radar backscatter over vegetated areas, which might be attributed to mass changes of the vegetation layer. Field measurements are required to study the driving processes. This study aims to use measured three-dimensional displacement and acceleration of trees, to detect and quantify their diurnal (bio)mass variations. Accelerometers and dendrometers were installed on seven different tree species in the Amazon rainforest. Trees were selected to cover a broad range of wood density. Using spectral analysis, the governing frequencies in the acceleration time series were found. The governing frequencies showed a diurnal pattern, as well as a change during precipitation events. Our results suggest that we can separate and potentially quantify tree mass changes due to (1) internal water redistribution and (2) intercepted precipitation. This will allow further investigation of the effect of precipitation and water stress on tree dynamics in forest canopies.

  12. Translating Mouse Vocalizations: Prosody and Frequency Modulation

    PubMed Central

    Lahvis, Garet P.; Alleva, Enrico; Scattoni, Maria Luisa

    2010-01-01

    Mental illness can include impaired abilities to express emotions or respond to the emotions of others. Speech provides a mechanism for expressing emotions, by both what words are spoken and by the melody or intonation of speech (prosody). Through the perception of variations in prosody, an individual can detect changes in another's emotional state. Prosodic features of mouse ultrasonic vocalizations (USVs), indicated by changes in frequency and amplitude, also convey information. Dams retrieve pups that emit separation calls, females approach males emitting solicitous calls, and mice can become fearful of a cue associated with the vocalizations of a distressed conspecific. Since acoustic features of mouse USVs respond to drugs and genetic manipulations that influence reward circuits, USV analysis can be employed to examine how genes influence social motivation, affect regulation, and communication. The purpose of this review is to discuss how genetic and developmental factors influence aspects of the mouse vocal repertoire and how mice respond to the vocalizations of their conspecifics. To generate falsifiable hypotheses about the emotional content of particular calls, this review addresses USV analysis within the framework of affective neuroscience (e.g. measures of motivated behavior such as conditioned place preference tests, brain activity, and systemic physiology). Suggested future studies include employment of an expanded array of physiological and statistical approaches to identify the salient acoustic features of mouse vocalizations. We are particularly interested in rearing environments that incorporate sufficient spatial and temporal complexity to familiarize developing mice with a broader array of affective states. PMID:20497235

  13. Depth-Duration Frequency of Precipitation for Oklahoma

    USGS Publications Warehouse

    Tortorelli, Robert L.; Rea, Alan; Asquith, William H.

    1999-01-01

    A regional frequency analysis was conducted to estimate the depth-duration frequency of precipitation for 12 durations in Oklahoma (15, 30, and 60 minutes; 1, 2, 3, 6, 12, and 24 hours; and 1, 3, and 7 days). Seven selected frequencies, expressed as recurrence intervals, were investigated (2, 5, 10, 25, 50, 100, and 500 years). L-moment statistics were used to summarize depth-duration data and to determine the appropriate statistical distributions. Three different rain-gage networks provided the data (15minute, 1-hour, and 1-day). The 60-minute, and 1-hour; and the 24-hour, and 1-day durations were analyzed separately. Data were used from rain-gage stations with at least 10-years of record and within Oklahoma or about 50 kilometers into bordering states. Precipitation annual maxima (depths) were determined from the data for 110 15-minute, 141 hourly, and 413 daily stations. The L-moment statistics for depths for all durations were calculated for each station using unbiased L-mo-ment estimators for the mean, L-scale, L-coefficient of variation, L-skew, and L-kur-tosis. The relation between L-skew and L-kurtosis (L-moment ratio diagram) and goodness-of-fit measures were used to select the frequency distributions. The three-parameter generalized logistic distribution was selected to model the frequencies of 15-, 30-, and 60-minute annual maxima; and the three-parameter generalized extreme-value distribution was selected to model the frequencies of 1-hour to 7-day annual maxima. The mean for each station and duration was corrected for the bias associated with fixed interval recording of precipitation amounts. The L-scale and spatially averaged L-skew statistics were used to compute the location, scale, and shape parameters of the selected distribution for each station and duration. The three parameters were used to calculate the depth-duration-frequency relations for each station. The precipitation depths for selected frequencies were contoured from weighted depth

  14. Partnership concurrency and coital frequency.

    PubMed

    Gaydosh, Lauren; Reniers, Georges; Helleringer, Stéphane

    2013-09-01

    National HIV prevalence estimates across sub-Saharan Africa range from less than 1 percent to over 25 percent. Recent research proposes several explanations for the observed variation, including prevalence of male circumcision, levels of condom use, presence of other sexually transmitted infections, and practice of multiple concurrent partnerships. However, the importance of partnership concurrency for HIV transmission may depend on how it affects coital frequency with each partner. The coital dilution hypothesis suggests that coital frequency within a partnership declines with the addition of concurrent partners. Using sexual behavior data from rural Malawi and urban Kenya, we investigate the relationship between partnership concurrency and coital frequency, and find partial support for the coital dilution hypothesis. We conclude the paper with a discussion of our findings in light of the current literature on concurrency.

  15. Vibration of visco-elastic rectangular plate with linearly thickness variations in both directions

    NASA Astrophysics Data System (ADS)

    Gupta, A. K.; Khanna, A.

    2007-04-01

    The analysis presented here is to study the effect of linear thickness variations in both directions on vibration of visco-elastic rectangular plate having clamped boundary conditions on all the four edges. Using the separation of variables method, the governing differential equation has been solved for vibration of visco-elastic rectangular plate. An approximate but quite convenient frequency equation is derived by using Rayleigh-Ritz technique with a two-term deflection function. Logarithmic decrement, time period and deflection at different points for the first two modes of vibration are calculated for various values of taper constants and aspect ratio.

  16. Novel Separation of Actinides

    SciTech Connect

    Mariella, R

    2011-02-17

    The separation of actinides and other elements of interest for nuclear forensics and threat reduction is currently performed using decades-old chemistries and ion-exchange columns. We propose to determine the technical feasibility of a novel method for separating actinide ions in solution. This method is based upon isotachophoresis (ITP), which has been applied in the purification of pharmaceuticals and other biochemical applications. This technique has the potential to separate inorganic ions more effectively than existing methods, which is key to analyzing very small samples. We will perform a quantitative assessment of the effectiveness of specific isotachophoretic approaches including predicting the physical and chemical properties, such as ion mobility, of inorganic ions under specific solvent conditions using a combination of ab initio calculations and semi-empirical methods. We expect to obtain a thorough understanding of the analytical systems parameters under which ITP is most effective for the separation of inorganic samples, including the influence of the double layer surrounding actinide ions, the Debye length for different ions and ion complexes, and Debye-Hueckel limits. Inorganic separations are key to nuclear forensics for countering terrorism and nuclear proliferation. If found to be feasible and potentially superior to currently used separation approaches, ITP could provide the conceptual basis for an improved means to separate samples of nuclear explosion debris for nuclear forensic analysis, in support of the Laboratory's missions in homeland and national security.

  17. Relationship between the transition frequency of local fluid flow and the peak frequency of attenuation

    NASA Astrophysics Data System (ADS)

    Cao, Cheng-Hao; Zhang, Hong-Bing; Pan, Yi-Xin; Teng, Xin-Bao

    2016-03-01

    Local fluid flow (LFF) at the mesoscopic scale is the main dissipation mechanism of seismic waves in heterogeneous porous media within the seismic frequency band. LFF is easily influenced by the structure and boundary conditions of the porous media, which leads to different behaviors of the peak frequency of attenuation. The associated transition frequency can provide detailed information about the trend of LFF; therefore, research on the transition frequency of LFF and its relationship with the peak frequency of the corresponding attenuation (i.e., inverse of quality factor) facilitates the detailed understanding of the effect of inner structures and boundary conditions in porous media. In this study, we firstly obtain the transition frequency of fluid flux based on Biot's theory of poroelasticity and the fast Fourier transform algorithm in a sample containing one repeating unit cell (RUC). We then analyze changes of these two frequencies in porous media with different porous properties. Finally, we extend our analysis to the influence of the undrained boundary condition on the transition frequency and peak frequency in porous media with multiple RUCs. This setup can facilitate the understanding of the effect from the undrained boundary condition. Results demonstrate that these two frequencies have the same trend at low water saturation, but amplitude variations differ between the frequencies as the amount of saturation increases. However, for cases of high water saturation, both the trend and the amplitude variation of these two frequencies fit well with each other.

  18. High frequency noise studies at the Hartousov mofette area (CZE)

    NASA Astrophysics Data System (ADS)

    Schmidt, Andreas; Flores-Estrella, Hortencia; Pommerencke, Julia; Umlauft, Josefine

    2014-05-01

    Ambient noise analysis has been used as a reliable tool to investigate sub-surface structures at seismological quiet regions with none or less specific seismic events. Here, we consider the acoustic signals from a single mofette at the Hartoušov area (CZE) as a noise-like high frequency source caused by multiple near surface degassing processes in a restricted location. From this assumption we have used different array geometries for recording at least one hour of continuous noise. We installed triangular arrays with 3 component geophones: the first deployment consisted on two co-centric triangles with side length of 30 and 50 m with the mofette in the center; the second deployment consisted on two triangular arrays, both with side length of 30 m, co-directional to the mofette. Furthermore, we also installed profiles with 24 channels and vertical geophones locating them in different positions with respect to the mofette. In this work, we present preliminary results from the data analysis dependent on the geometry, to show the characteristics of the noise wave-field referring to frequency content and propagation features, such as directionality and surface wave velocity. The spectral analysis shows that the energy is concentrated in a frequency band among 10 and 40 Hz. However, in this interval there is no evidence of any exclusive fundamental frequencies. From this, man-induced influences can be identified as intermittent signal peaks in narrow frequency bands and can be separated to receive the revised mofette wave-field record. The inversion of dispersive surface waves, that were detected by interferometric methods, provides a velocity model down to 12 m with an S-wave velocity between 160 and 180 m/s on the uppermost layer. Furthermore, the interferometric signal properties indicate that it is not possible to characterize the mofette as a punctual source, but rather as a conglomerate of multiple sources with time and location variations.

  19. Giant Crab pulses at low frequency: statistics, scattering, polarization

    SciTech Connect

    Smirnova, T. V.

    2010-01-01

    We carried out observations of Crab giant pulses at frequency 112 MHz from 2005 till 2008 on the Large Phased Array of the Pushchino Radio Astronomy Observatory. The scattering of pulses observed in various series varies by a factor of 3: from 11 ms in November 2005 till 34 ms in September 2008. The cumulative probability distribution for the peak intensities of the giant pulses for each of these series shows that the distribution is stable and is a power law with a single slope (n = -2.3). This testifies to stability of the mechanism generating the giant pulses. The energy in the pulses is conserved; i.e., the increase in the pulse intensity is proportional to the decrease in the scattering. Refractive scintillations at low frequencies in measurements with large time separation lead to variations in the relative number of giant pulses exceeding a given amplitude, proportional to the ratio of the mean flux densities of the pulsar in the corresponding observational series. The maximum energy of the recorded giant pulses is 2.5x10{sup 7} Jy mus. Analysis of the giant pulses observed at other frequencies shows that the frequency dependence of the maximum energy of the giant pulses in the range of 23 MHz-9 GHz is a power-law with index -2.2+-0.2. We measured the rotation measure using GP which is RM (-47.5+-0.4) rad/m{sup 2}, and the degree of linear polarization for pulses with measured frequency modulation was 9% divide 17% for November 2005.

  20. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, F.T.

    Intermetallic compounds with the CaCu/sub 5/ type of crystal structure, particularly LaNiCo/sub 4/ and CaNi/sub 5/, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen cn produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  1. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  2. Materials separation by dielectrophoresis

    NASA Technical Reports Server (NTRS)

    Sagar, A. D.; Rose, R. M.

    1988-01-01

    The feasibility of vacuum dielectrophoresis as a method for particulate materials separation in a microgravity environment was investigated. Particle separations were performed in a specially constructed miniature drop-tower with a residence time of about 0.3 sec. Particle motion in such a system is independent of size and based only on density and dielectric constant, for a given electric field. The observed separations and deflections exceeded the theoretical predictions, probably due to multiparticle effects. In any case, this approach should work well in microgravity for many classes of materials, with relatively simple apparatus and low weight and power requirements.

  3. Rotary drum separator system

    NASA Technical Reports Server (NTRS)

    Barone, Michael R. (Inventor); Murdoch, Karen (Inventor); Scull, Timothy D. (Inventor); Fort, James H. (Inventor)

    2009-01-01

    A rotary phase separator system generally includes a step-shaped rotary drum separator (RDS) and a motor assembly. The aspect ratio of the stepped drum minimizes power for both the accumulating and pumping functions. The accumulator section of the RDS has a relatively small diameter to minimize power losses within an axial length to define significant volume for accumulation. The pumping section of the RDS has a larger diameter to increase pumping head but has a shorter axial length to minimize power losses. The motor assembly drives the RDS at a low speed for separating and accumulating and a higher speed for pumping.

  4. Autistic Children's Responses to Separation and Reunion with Their Mothers.

    ERIC Educational Resources Information Center

    Dissanayake, Cheryl; Crossley, Stella A.

    1997-01-01

    A study of 16 children with autism, 16 typical children, and 16 children with Downs syndrome (ages 3-6) investigated children's responses to separation and reunion with their mothers. No differences were found between groups; however, the children with disabilities showed more individual variation in separation and reunion patterns. (Author/CR)

  5. Particle separation by dielectrophoresis

    PubMed Central

    Gascoyne, Peter R. C.; Vykoukal, Jody

    2009-01-01

    The application of dielectrophoresis to particle discrimination, separation, and fractionation is reviewed, some advantages and disadvantages of currently available approaches are considered, and some caveats are noted. PMID:12210248

  6. Inorganic separator technology program

    NASA Technical Reports Server (NTRS)

    Smatko, J. S.; Weaver, R. D.; Kalhammer, F. R.

    1973-01-01

    Testing and failure analyses of silver zinc cells with largely inorganic separators were performed. The results showed that the wet stand and cycle life objective of the silver-zinc cell development program were essentially accomplished and led to recommendations for cell composition, design, and operation that should yield further improvement in wet and cycle life. A series of advanced inorganic materials was successfully developed and formulated into rigid and semiflexible separator samples. Suitable screening tests for evaluation of largely inorganic separators were selected and modified for application to the separator materials. The results showed that many of these formulations are potentially superior to previously used materials and permitted selection of three promising materials for further evaluation in silver-zinc cells.

  7. Gas-separation process

    DOEpatents

    Toy, Lora G.; Pinnau, Ingo; Baker, Richard W.

    1994-01-01

    A process for separating condensable organic components from gas streams. The process makes use of a membrane made from a polymer material that is glassy and that has an unusually high free volume within the polymer material.

  8. Plasma isotope separation methods

    SciTech Connect

    Grossman, M.W. ); Shepp, T.A. )

    1991-12-01

    Isotope separation has many important industrial, medical, and research applications. Large-scale processes have typically utilized complex cascade systems; for example, the gas centrifuge. Alternatively, high single-stage enrichment processes (as in the case of the calutron) are very energy intensive. Plasma-based methods being developed for the past 15 to 20 years have attempted to overcome these two drawbacks. In this review, six major types of isotope separation methods which involve plasma phenomena are discussed. These methods are: plasma centrifuge, AVLIS (atomic vapor laser isotope separation), ion wave, ICR (ion-cyclotron resonance), calutron, and gas discharge. The emphasis of this paper is to describe the plasma phenomena in these major categories. An attempt was made to include enough references so that more detailed study or evaluation of a particular method could readily be pursued. A brief discussion of isotope separation using mass balance concepts is also carried out.

  9. Separation by solvent extraction

    DOEpatents

    Holt, Jr., Charles H.

    1976-04-06

    17. A process for separating fission product values from uranium and plutonium values contained in an aqueous solution, comprising adding an oxidizing agent to said solution to secure uranium and plutonium in their hexavalent state; contacting said aqueous solution with a substantially water-immiscible organic solvent while agitating and maintaining the temperature at from -1.degree. to -2.degree. C. until the major part of the water present is frozen; continuously separating a solid ice phase as it is formed; separating a remaining aqueous liquid phase containing fission product values and a solvent phase containing plutonium and uranium values from each other; melting at least the last obtained part of said ice phase and adding it to said separated liquid phase; and treating the resulting liquid with a new supply of solvent whereby it is practically depleted of uranium and plutonium.

  10. Laser-Beam Separator

    NASA Technical Reports Server (NTRS)

    Mcdermid, I. S.

    1984-01-01

    Train of prisms and optical stop separate fundamental beam of laser from second and higher order harmonics of beam produced in certain crystals and by stimulated Raman scattering in gases and liquids.

  11. Microsystem capillary separations

    DOEpatents

    TeGrotenhuis, Ward E [Kennewick, WA; Wegeng, Robert S [Richland, WA; Whyatt, Greg A [West Richland, WA; Stenkamp, Victoria S [Richland, WA; Gauglitz, Phillip A [Richland, WA

    2003-12-23

    Laminated, multiphase separators and contactors having wicking structures and gas flow channels are described. Some preferred embodiments are combined with microchannel heat exchange. Integrated systems containing these components are also part of the present invention.

  12. Separator for alkaline batteries

    NASA Technical Reports Server (NTRS)

    Hoyt, H. W.; Pfluger, H. L.

    1968-01-01

    Separator compositions have been tested as components of three-plate silver-zinc oxide cells in a standard cycling test. Six materials meet imposed requirements, giving cycling performance superior to cellophane.

  13. Galvanic cell separator

    SciTech Connect

    Fujiwara, K.; Osawa, K.; Takeda, Y.; Yabumoto, T.

    1981-07-07

    A galvanic cell separator is disclosed that is composed of polyvinyl alcohol having a crystallinity of 0.4 or more to be used with a galvanic cell containing alkaline electrolyte, and a method of manufacturing the same.

  14. Acoustic particle separation

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Stoneburner, J. D.; Jacobi, N.; Wang, T. (Inventor)

    1985-01-01

    A method is described which uses acoustic energy to separate particles of different sizes, densities, or the like. The method includes applying acoustic energy resonant to a chamber containing a liquid of gaseous medium to set up a standing wave pattern that includes a force potential well wherein particles within the well are urged towards the center, or position of minimum force potential. A group of particles to be separated is placed in the chamber, while a non-acoustic force such as gravity is applied, so that the particles separate with the larger or denser particles moving away from the center of the well to a position near its edge and progressively smaller lighter particles moving progressively closer to the center of the well. Particles are removed from different positions within the well, so that particles are separated according to the positions they occupy in the well.

  15. Separable Arrowhead Microneedles

    PubMed Central

    Chu, Leonard Y.; Prausnitz, Mark R.

    2010-01-01

    Hypodermic needles cause pain and bleeding, produce biohazardous sharp waste and require trained personnel. To address these issues, we introduce separable arrowhead microneedles that rapidly and painlessly deliver drugs and vaccines to the skin. These needles are featured by micron-size sharp tips mounted on blunt shafts. Upon insertion in the skin, the sharp-tipped polymer arrowheads encapsulating drug separate from their metal shafts and remain embedded in the skin for subsequent dissolution and drug release. The blunt metal shafts can then be discarded. Due to rapid separation of the arrowhead tips from the shafts within seconds, administration using arrowhead microneedles can be carried out rapidly, while drug release kinetics can be independently controlled based on separable arrowhead formulation. Thus, drug and vaccine delivery using arrowhead microneedles are designed to offer a quick, convenient, safe and potentially self-administered method of drug delivery as an alternative to hypodermic needles. PMID:21047538

  16. Monitored separation device

    NASA Technical Reports Server (NTRS)

    Jackson, George William (Inventor); Willson, Richard Coale (Inventor); Fox, George Edward (Inventor)

    2011-01-01

    A device for separating and purifying useful quantities of particles comprises: a. an anolyte reservoir connected to an anode, the anolyte reservoir containing an electrophoresis buffer; b. a catholyte reservoir connected to a cathode, the catholyte reservoir also containing the electrophoresis buffer; c. a power supply connected to the anode and to the cathode; d. a column having a first end inserted into the anolyte reservoir, a second end inserted into the catholyte reservoir, and containing a separation medium; e. a light source; f. a first optical fiber having a first fiber end inserted into the separation medium, and having a second fiber end connected to the light source; g. a photo detector; h. a second optical fiber having a third fiber end inserted into the separation medium, and having a fourth fiber end connected to the photo detector; and i. an ion-exchange membrane in the anolyte reservoir.

  17. Molten salt electrolyte separator

    DOEpatents

    Kaun, Thomas D.

    1996-01-01

    A molten salt electrolyte/separator for battery and related electrochemical systems including a molten electrolyte composition and an electrically insulating solid salt dispersed therein, to provide improved performance at higher current densities and alternate designs through ease of fabrication.

  18. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  19. Frequency-Rank Distributions

    ERIC Educational Resources Information Center

    Brookes, Bertram C.; Griffiths, Jose M.

    1978-01-01

    Frequency, rank, and frequency rank distributions are defined. Extensive discussion on several aspects of frequency rank distributions includes the Poisson process as a means of exploring the stability of ranks; the correlation of frequency rank distributions; and the transfer coefficient, a new measure in frequency rank distribution. (MBR)

  20. SEPARATIONS BY ELECTRODIALYSIS

    DOEpatents

    Webb, W.H.; Vie, J.D.

    1962-06-12

    A method is given for separating cesium, cerium, zirconium, and uranyl ions frora a common solution by electrodialysis. An anion exchange membrane and a cation exchange membrane are placed on either side of the feed solution compartment; the former is in electrolytic contact with an anode and the latter with cathode. On acidification of the feed solution to a critical value of 0.5 N and passage of a current from the anode to the cathode, the desired separations tske place. (AEC)

  1. Interactive separating streak surfaces.

    PubMed

    Ferstl, Florian; Bürger, Kai; Theisel, Holger; Westermann, Rüdiger

    2010-01-01

    Streak surfaces are among the most important features to support 3D unsteady flow exploration, but they are also among the computationally most demanding. Furthermore, to enable a feature driven analysis of the flow, one is mainly interested in streak surfaces that show separation profiles and thus detect unstable manifolds in the flow. The computation of such separation surfaces requires to place seeding structures at the separation locations and to let the structures move correspondingly to these locations in the unsteady flow. Since only little knowledge exists about the time evolution of separating streak surfaces, at this time, an automated exploration of 3D unsteady flows using such surfaces is not feasible. Therefore, in this paper we present an interactive approach for the visual analysis of separating streak surfaces. Our method draws upon recent work on the extraction of Lagrangian coherent structures (LCS) and the real-time visualization of streak surfaces on the GPU. We propose an interactive technique for computing ridges in the finite time Lyapunov exponent (FTLE) field at each time step, and we use these ridges as seeding structures to track streak surfaces in the time-varying flow. By showing separation surfaces in combination with particle trajectories, and by letting the user interactively change seeding parameters such as particle density and position, visually guided exploration of separation profiles in 3D is provided. To the best of our knowledge, this is the first time that the reconstruction and display of semantic separable surfaces in 3D unsteady flows can be performed interactively, giving rise to new possibilities for gaining insight into complex flow phenomena.

  2. Separator performance evaluation

    SciTech Connect

    Barker, W.F.

    1982-01-01

    Retrograde condensates and various contaminants are normally trapped and removed from high-pressure transmission lines by means of inline drips, siphon drips, impingement drips, and gas-liquid separators. These mechanical devices can be vertical, horizontal, or spherical. The horizontal design gives the most efficient operation at high pressures for the initial investment cost. Removal of particulates smaller than 10 micrometers in diameter requires special separators such as a filter coalescing device designed specifically for mists, oil fogs, rust, and dust.

  3. Hydrogen separation process

    DOEpatents

    Mundschau, Michael; Xie, Xiaobing; Evenson, IV, Carl; Grimmer, Paul; Wright, Harold

    2011-05-24

    A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than 200.degree. C., to a hydrogen separation membrane system comprising a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than 200.degree. C., to an integrated water gas shift/hydrogen separation membrane system wherein the hydrogen separation membrane system comprises a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for pretreating a membrane, comprising: heating the membrane to a desired operating temperature and desired feed pressure in a flow of inert gas for a sufficient time to cause the membrane to mechanically deform; decreasing the feed pressure to approximately ambient pressure; and optionally, flowing an oxidizing agent across the membrane before, during, or after deformation of the membrane. A method of supporting a hydrogen separation membrane system comprising selecting a hydrogen separation membrane system comprising one or more catalyst outer layers deposited on a hydrogen transport membrane layer and sealing the hydrogen separation membrane system to a porous support.

  4. Distal humeral epiphyseal separation.

    PubMed

    Moucha, Calin S; Mason, Dan E

    2003-10-01

    Distal humeral epiphyseal separation is an uncommon injury that is often misdiagnosed upon initial presentation. To make a timely, correct diagnosis, the treating physician must have a thorough understanding of basic anatomical relationships and an awareness of the existence of this injury. This is a case of a child who sustained a separation of the distal humeral epiphysis, as well as multiple other bony injuries, secondary to child abuse.

  5. Variational integrators for electric circuits

    SciTech Connect

    Ober-Blöbaum, Sina; Tao, Molei; Cheng, Mulin; Owhadi, Houman; Marsden, Jerrold E.

    2013-06-01

    In this contribution, we develop a variational integrator for the simulation of (stochastic and multiscale) electric circuits. When considering the dynamics of an electric circuit, one is faced with three special situations: 1. The system involves external (control) forcing through external (controlled) voltage sources and resistors. 2. The system is constrained via the Kirchhoff current (KCL) and voltage laws (KVL). 3. The Lagrangian is degenerate. Based on a geometric setting, an appropriate variational formulation is presented to model the circuit from which the equations of motion are derived. A time-discrete variational formulation provides an iteration scheme for the simulation of the electric circuit. Dependent on the discretization, the intrinsic degeneracy of the system can be canceled for the discrete variational scheme. In this way, a variational integrator is constructed that gains several advantages compared to standard integration tools for circuits; in particular, a comparison to BDF methods (which are usually the method of choice for the simulation of electric circuits) shows that even for simple LCR circuits, a better energy behavior and frequency spectrum preservation can be observed using the developed variational integrator.

  6. Physical origin of the frequency shifts in cesium beam frequency standards: Related environmental sensitivity

    NASA Technical Reports Server (NTRS)

    Audoin, Claude; Dimarcq, N.; Giordano, V.; Viennet, J.

    1990-01-01

    When observed in a cesium beam frequency standard, the hyperfine transition frequency of the atoms differs slightly from the invariant transition frequency of the unperturbed atoms at rest. The various physical and technical origins of the frequency offsets are stated. They relate to fundamental physical effects, to the method of probing the atomic resonance and to the frequency control of the slaved oscillator. The variation of the frequency offsets under a change of the value of the internal operating characteristics is considered. The sensitivity to a change of the magnetic induction, the microwave power, and the temperature is given. A comparison is made of the sensitivity of cesium beam frequency standards of the commercially available type, making use of magnetic state selection, and of devices under study, in which the state preparation and detection is accomplished optically. The pathways between the external stimuli and the physical origin of the frequency offsets are specified.

  7. Microflotation performance for algal separation.

    PubMed

    Hanotu, James; Bandulasena, H C Hemaka; Zimmerman, William B

    2012-07-01

    The performance of microflotation, dispersed air flotation with microbubble clouds with bubble size about 50 µm, for algae separation using fluidic oscillation for microbubble generation is investigated. This fluidic oscillator converts continuous air supply into oscillatory flow with a regular frequency to generate bubbles of the scale of the exit pore. Bubble characterization results showed that average bubble size generated under oscillatory air flow state was 86 µm, approximately twice the size of the diffuser pore size of 38 µm. In contrast, continuous air flow at the same rate through the same diffusers yielded an average bubble size of 1,059 µm, 28 times larger than the pore size. Following microbubble generation, the separation of algal cells under fluidic oscillator generated microbubbles was investigated by varying metallic coagulant types, concentration and pH. Best performances were recorded at the highest coagulant dose (150 mg/L) applied under acidic conditions (pH 5). Amongst the three metallic coagulants studied, ferric chloride yielded the overall best result of 99.2% under the optimum conditions followed closely by ferric sulfate (98.1%) and aluminum sulfate with 95.2%. This compares well with conventional dissolved air flotation (DAF) benchmarks, but has a highly turbulent flow, whereas microflotation is laminar with several orders of magnitude lower energy density.

  8. Unsteady Aerodynamic Response of a Linear Cascade of Airfoils in Separated Flow

    NASA Technical Reports Server (NTRS)

    Capece, Vincent R.; Ford, Christopher; Bone, Christopher; Li, Rui

    2004-01-01

    The overall objective of this research program was to investigate methods to modify the leading edge separation region, which could lead to an improvement in aeroelastic stability of advanced airfoil designs. The airfoil section used is representative of current low aspect ratio fan blade tip sections. The experimental potion of this study investigated separated zone boundary layer from removal through suction slots. Suction applied to a cavity in the vicinity of the separation onset point was found to be the most effective location. The computational study looked into the influence of front camber on flutter stability. To assess the influence of the change in airfoil shape on stability the work-per-cycle was evaluated for torsion mode oscillations. It was shown that the front camberline shape can be an important factor for stabilizing the predicted work-per-cycle and reducing the predicted extent of the separation zone. In addition, data analysis procedures are discussed for reducing data acquired in experiments that involve periodic unsteady data. This work was conducted in support of experiments being conducted in the NASA Glenn Research Center Transonic Flutter Cascade. The spectral block averaging method is presented. This method is shown to be able to account for variations in airfoil oscillation frequency that can occur in experiments that force oscillate the airfoils to simulate flutter.

  9. Rotating speed isolation and its application to rolling element bearing fault diagnosis under large speed variation conditions

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Xu, Guanghua; Zhang, Qing; Liu, Dan; Jiang, Kuosheng

    2015-07-01

    During the past decades, the conventional envelope analysis has been one of the main approaches in vibration signal processing. However, the envelope analysis is based on stationary assumption, thus it is not applicable to the fault diagnosis of bearings under rotating speed variation conditions. This constraint limits the bearing diagnosis in industrial applications significantly. In order to extend the conventional diagnosis technique to speed variation cases, a rotating speed isolation method is proposed. This method consists of four main steps: (a) a low-pass filter is used to separate the rotating speed components and the resonance frequency band from the original signal; (b) the trend line of instantaneous rotating frequency (IRF) is extracted by ridge detection from the short-time spectrum of the low-pass filtered signal; (c) the envelope signal is obtained by fast kurtogram based resonance demodulation; (d) the trend line of instantaneous fault characteristic frequency (IFCF) is extracted by ridge detection from the short-time spectrum of the envelope signal; (e) the rotating speed is isolated and the instantaneous fault characteristic order (FCO), which is obtained by simply dividing the IFCF by IRF, can be used to identify the fault type. By rotating speed isolation, the bearing faults under speed variation conditions can be detected without additional tachometers. The effectiveness of the proposed method has been validated by both simulated and experimental bearing vibration signals. The results show that the proposed method outperforms the conventional envelope analysis method and is effective in bearing diagnosis under speed variation conditions.

  10. Cluster analysis of word frequency dynamics

    NASA Astrophysics Data System (ADS)

    Maslennikova, Yu S.; Bochkarev, V. V.; Belashova, I. A.

    2015-01-01

    This paper describes the analysis and modelling of word usage frequency time series. During one of previous studies, an assumption was put forward that all word usage frequencies have uniform dynamics approaching the shape of a Gaussian function. This assumption can be checked using the frequency dictionaries of the Google Books Ngram database. This database includes 5.2 million books published between 1500 and 2008. The corpus contains over 500 billion words in American English, British English, French, German, Spanish, Russian, Hebrew, and Chinese. We clustered time series of word usage frequencies using a Kohonen neural network. The similarity between input vectors was estimated using several algorithms. As a result of the neural network training procedure, more than ten different forms of time series were found. They describe the dynamics of word usage frequencies from birth to death of individual words. Different groups of word forms were found to have different dynamics of word usage frequency variations.

  11. Graph Frequency Analysis of Brain Signals

    NASA Astrophysics Data System (ADS)

    Huang, Weiyu; Goldsberry, Leah; Wymbs, Nicholas F.; Grafton, Scott T.; Bassett, Danielle S.; Ribeiro, Alejandro

    2016-10-01

    This paper presents methods to analyze functional brain networks and signals from graph spectral perspectives. The notion of frequency and filters traditionally defined for signals supported on regular domains such as discrete time and image grids has been recently generalized to irregular graph domains, and defines brain graph frequencies associated with different levels of spatial smoothness across the brain regions. Brain network frequency also enables the decomposition of brain signals into pieces corresponding to smooth or rapid variations. We relate graph frequency with principal component analysis when the networks of interest denote functional connectivity. The methods are utilized to analyze brain networks and signals as subjects master a simple motor skill. We observe that brain signals corresponding to different graph frequencies exhibit different levels of adaptability throughout learning. Further, we notice a strong association between graph spectral properties of brain networks and the level of exposure to tasks performed, and recognize the most contributing and important frequency signatures at different task familiarity.

  12. Organic Separation Test Results

    SciTech Connect

    Russell, Renee L.; Rinehart, Donald E.; Peterson, Reid A.

    2014-09-22

    Separable organics have been defined as “those organic compounds of very limited solubility in the bulk waste and that can form a separate liquid phase or layer” (Smalley and Nguyen 2013), and result from three main solvent extraction processes: U Plant Uranium Recovery Process, B Plant Waste Fractionation Process, and Plutonium Uranium Extraction (PUREX) Process. The primary organic solvents associated with tank solids are TBP, D2EHPA, and NPH. There is concern that, while this organic material is bound to the sludge particles as it is stored in the tanks, waste feed delivery activities, specifically transfer pump and mixer pump operations, could cause the organics to form a separated layer in the tank farms feed tank. Therefore, Washington River Protection Solutions (WRPS) is experimentally evaluating the potential of organic solvents separating from the tank solids (sludge) during waste feed delivery activities, specifically the waste mixing and transfer processes. Given the Hanford Tank Waste Treatment and Immobilization Plant (WTP) waste acceptance criteria per the Waste Feed Acceptance Criteria document (24590-WTP-RPT-MGT-11-014) that there is to be “no visible layer” of separable organics in the waste feed, this would result in the batch being unacceptable to transfer to WTP. This study is of particular importance to WRPS because of these WTP requirements.

  13. INDIVIDUAL VARIATION IN THE FREQUENCY OF SPERM ANEUPLOIDY IN HUMANS

    EPA Science Inventory

    To examine interindividual differences in sperm chromosome aneuploidy, repeated semen specimens were obtained from a group of ten healthy men, aged 20-21 at the start of the study, and analyzed by multi-color fluorescence in situ hybridization (FISH) analysis to determine the fre...

  14. Spatial variation of coda wave attenuation in northwestern Colombia

    NASA Astrophysics Data System (ADS)

    Vargas, Carlos A.; Ugalde, Arantza; Pujades, Lluís G.; Canas, José A.

    2004-08-01

    One thousand seven hundred and eighty-six vertical-component, short-period observations of microearthquake codas from regional earthquakes recorded by 17 stations belonging to the National Seismological Network of Colombia were used to estimate seismic wave attenuation in Colombia. Local magnitudes range from 2.9 to 6.0 and only events occurring at hypocentral distances up to 255 km were considered for the analysis. The frequencies of interest lay between 1 and 19 Hz and the analysis was performed for each seismic station separately. Coda-wave attenuation (Q-1c) was estimated by means of a single-scattering method whereas the separation of intrinsic absorption (Q-1i) and scattering attenuation (Q-1s) from total attenuation (Q-1t) was performed using a multiple lapse time-window analysis based on the hypothesis of multiple isotropic scattering and uniform distribution of scatterers. A regionalization of the estimated Q0 (Qc at 1 Hz) values was performed and a contour map of seismic coda attenuation in Colombia is presented, where four zones with significant variations of attenuation related to different geological and tectonic characteristics can be observed. The highest attenuation is linked to the central and western regions (Q0 around 50 and 56) whereas a lower attenuation (Q0 around 69 and 67) is assigned to the northern and eastern regions. Results show that the Q-1 values are frequency dependent in the considered frequency range, and are approximated by a least-square fit to the power law Q-1(f) =Q-10(f/f0)-η. The exponents of the frequency dependence law ranged from η= 0.65 to 1.01 for Q-1c, η= 0.62 to 1.78 for Q-1i, η= 0.28 to 1.49 for Q-1s, and η= 0.53 to 1.67 for Q-1t. On the other hand, intrinsic absorption is found to dominate over scattering in the attenuation process for most of the stations and frequency bands analysed. Some discrepancies have been observed between the theoretical model and the observations for some frequency bands which indicate

  15. Dielectrophoretic Separation of Cancer Cells from Blood

    PubMed Central

    Gascoyne, Peter R. C.; Wang, Xiao-Bo; Huang, Ying; Becker, Frederick F.

    2009-01-01

    Recent measurements have demonstrated that the dielectric properties of cells depend on their type and physiological status. For example, MDA-231 human breast cancer cells were found to have a mean plasma membrane specific capacitance of 26 mF/m2, more than double the value (11 mF/m2) observed for resting T-lymphocytes. When an inhomogeneous ac electric field is applied to a particle, a dielectrophoretic (DEP) force arises that depends on the particle dielectric properties. Therefore, cells having different dielectric characteristics will experience differential DEP forces when subjected to such a field. In this article, we demonstrate the use of differential DEP forces for the separation of several different cancerous cell types from blood in a dielectric affinity column. These separations were accomplished using thin, flat chambers having microelectrode arrays on the bottom wall. DEP forces generated by the application of ac fields to the electrodes were used to influence the rate of elution of cells from the chamber by hydrodynamic forces within a parabolic fluid flow profile. Electrorotation measurements were first made on the various cell types found within cell mixtures to be separated, and theoretical modeling was used to derive the cell dielectric parameters. Optimum separation conditions were then predicted from the frequency and suspension conductivity dependencies of cell DEP responses defined by these parameters. Cell separations were then undertaken for various ratios of cancerous to normal cells at different concentrations. Eluted cells were characterized in terms of separation efficiency, cell viability, and separation speed. For example, 100% efficiency was achieved for purging MDA-231 cells from blood at the tumor to normal cell ratio 1:1 × 105 or 1:3 × 105, cell viability was not compromised, and separation rates were at least 103 cells/s. Theoretical and experimental criteria for the design and operation of such separators are presented. PMID

  16. Three-dimensional ray tracing of the Jovian magnetosphere in the low-frequency range

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Green, J. L.; Gulkis, S.; Six, F.

    1984-01-01

    Three-dimensional ray tracing of the Jovian DAM emission has been performed utilizing the O-4 magnetic field model (Acuna and Ness, 1979) and a realistic plasma model. Minimal assumptions about the emission mechanism have been made that include radiation in the right-hand extraordinary mode, propagating nearly perpendicular to the field line at source points located just above the RX cutoff frequency along Io flux tubes. Ray tracing has been performed in the frequency range from 2-35 MHz from successive Io flux tubes separated by ten degrees of central meridian longitude for a full circumference of northern hemisphere sources. The results show unusual complexity in model arc spectra that is displayed in a constant Io phase format with many similarities to the Voyager PRA data. The results suggest much of the variation in observed DAM spectral features is a result of propagation effects rather than emission process differences.

  17. Non-stationary hydrological frequency analysis based on the reconstruction of extreme hydrological series

    NASA Astrophysics Data System (ADS)

    Hu, Y. M.; Liang, Z. M.; Jiang, X. L.; Bu, H.

    2015-06-01

    In this paper, a novel approach for non-stationary hydrological frequency analysis is proposed. The approach is due to the following consideration that, at present the data series used to detect mutation characteristic is very short, which may only reflect the partial characteristic of the population. That is to say, the mutation characteristic of short series may not fully represent the mutation characteristic of population, such as the difference of mutation degree between short sample and population. In this proposed method, an assumption is done that the variation hydrological series in a big time window owns an expected vibration center (EVC), which is a linear combination of the two mean values of the two subsample series obtained through separating the original hydrological series by a novel optimal segmentation technique (change rate of slope method). Then using the EVC to reconstruct non-stationary series to meet the requirement of stationary, and further ensure the conventional frequency analysis methods is valid.

  18. Membrane separation of hydrocarbons

    DOEpatents

    Chang, Y. Alice; Kulkarni, Sudhir S.; Funk, Edward W.

    1986-01-01

    Mixtures of heavy oils and light hydrocarbons may be separated by passing the mixture through a polymeric membrane. The membrane which is utilized to effect the separation comprises a polymer which is capable of maintaining its integrity in the presence of hydrocarbon compounds and which has been modified by being subjected to the action of a sulfonating agent. Sulfonating agents which may be employed will include fuming sulfuric acid, chlorosulfonic acid, sulfur trioxide, etc., the surface or bulk modified polymer will contain a degree of sulfonation ranging from about 15 to about 50%. The separation process is effected at temperatures ranging from about ambient to about 100.degree. C. and pressures ranging from about 50 to about 1000 psig.

  19. Mass Separation by Metamaterials

    PubMed Central

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin

    2016-01-01

    Being able to manipulate mass flow is critically important in a variety of physical processes in chemical and biomolecular science. For example, separation and catalytic systems, which requires precise control of mass diffusion, are crucial in the manufacturing of chemicals, crystal growth of semiconductors, waste recovery of biological solutes or chemicals, and production of artificial kidneys. Coordinate transformations and metamaterials are powerful methods to achieve precise manipulation of molecular diffusion. Here, we introduce a novel approach to obtain mass separation based on metamaterials that can sort chemical and biomolecular species by cloaking one compound while concentrating the other. A design strategy to realize such metamaterial using homogeneous isotropic materials is proposed. We present a practical case where a mixture of oxygen and nitrogen is manipulated using a metamaterial that cloaks nitrogen and concentrates oxygen. This work lays the foundation for molecular mass separation in biophysical and chemical systems through metamaterial devices. PMID:26912419

  20. Mass Separation by Metamaterials

    NASA Astrophysics Data System (ADS)

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin

    2016-02-01

    Being able to manipulate mass flow is critically important in a variety of physical processes in chemical and biomolecular science. For example, separation and catalytic systems, which requires precise control of mass diffusion, are crucial in the manufacturing of chemicals, crystal growth of semiconductors, waste recovery of biological solutes or chemicals, and production of artificial kidneys. Coordinate transformations and metamaterials are powerful methods to achieve precise manipulation of molecular diffusion. Here, we introduce a novel approach to obtain mass separation based on metamaterials that can sort chemical and biomolecular species by cloaking one compound while concentrating the other. A design strategy to realize such metamaterial using homogeneous isotropic materials is proposed. We present a practical case where a mixture of oxygen and nitrogen is manipulated using a metamaterial that cloaks nitrogen and concentrates oxygen. This work lays the foundation for molecular mass separation in biophysical and chemical systems through metamaterial devices.

  1. Mass Separation by Metamaterials.

    PubMed

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin

    2016-01-01

    Being able to manipulate mass flow is critically important in a variety of physical processes in chemical and biomolecular science. For example, separation and catalytic systems, which requires precise control of mass diffusion, are crucial in the manufacturing of chemicals, crystal growth of semiconductors, waste recovery of biological solutes or chemicals, and production of artificial kidneys. Coordinate transformations and metamaterials are powerful methods to achieve precise manipulation of molecular diffusion. Here, we introduce a novel approach to obtain mass separation based on metamaterials that can sort chemical and biomolecular species by cloaking one compound while concentrating the other. A design strategy to realize such metamaterial using homogeneous isotropic materials is proposed. We present a practical case where a mixture of oxygen and nitrogen is manipulated using a metamaterial that cloaks nitrogen and concentrates oxygen. This work lays the foundation for molecular mass separation in biophysical and chemical systems through metamaterial devices. PMID:26912419

  2. Flow separation detector

    NASA Technical Reports Server (NTRS)

    Mateer, G. C.; Brosh, A. (Inventor)

    1977-01-01

    An arrangement for sensing the fluid separation along a surface which employs a thermally insulating element having a continuous surface blending into and forming a part of the fluid flow surface is described. A sudden decrease in the temperature of the downstream sensor conductor and concomitant increase in the temperature of the upstream sensor conductor is an indication of the separation. When the temperatures are returned to the state achieved during normal flow, the indicator thereby indicates the normal, attached fluid flow. The conductors may be, for example, wires or thin films, and should be within the viscous sub-layer of the expected fluid flow. A single heater and several pairs of sensors and corresponding sensor conductors may be used to detect not only the fluid flow and the separation, but the direction of the fluid flow, over the fluid flow surface.

  3. Mass Separation by Metamaterials.

    PubMed

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin

    2016-02-25

    Being able to manipulate mass flow is critically important in a variety of physical processes in chemical and biomolecular science. For example, separation and catalytic systems, which requires precise control of mass diffusion, are crucial in the manufacturing of chemicals, crystal growth of semiconductors, waste recovery of biological solutes or chemicals, and production of artificial kidneys. Coordinate transformations and metamaterials are powerful methods to achieve precise manipulation of molecular diffusion. Here, we introduce a novel approach to obtain mass separation based on metamaterials that can sort chemical and biomolecular species by cloaking one compound while concentrating the other. A design strategy to realize such metamaterial using homogeneous isotropic materials is proposed. We present a practical case where a mixture of oxygen and nitrogen is manipulated using a metamaterial that cloaks nitrogen and concentrates oxygen. This work lays the foundation for molecular mass separation in biophysical and chemical systems through metamaterial devices.

  4. Turbulent transition behavior in a separated and attached-flow low pressure turbine passage

    NASA Astrophysics Data System (ADS)

    Memory, Curtis L.

    Various time accurate numerical simulations were conducted on the aft-loaded L1A low pressure turbine airfoil operating at Reynolds numbers presenting with fully-stalled, non-reattaching laminar separation. The numerical solver TURBO was modified from its annular gas turbine simulation configuration to conduct simulations based on a linear cascade wind tunnel facility. Simulation results for the fully separated flow fields revealed various turbulent decay mechanisms. Separated shear layer decay, in the form of vortices forming between the shear layer and the blade wall, was shown to agree with experimental particle image velocimetry (PIV) data in terms of decay vortex size and core vorticity levels. These vortical structures eventually mix into a large recirculation zone which dominates the blade wake. Turbulent wake ex- tent and time-averaged velocity distributions agreed with PIV data. Steady-blowing vortex generating jet (VGJ) flow control was then applied to the flow fields. VGJ-induced streamwise vorticity was only present at blowing ratios above 1.5. VGJs actuated at the point of flow separation on the blade wall were more effective than those actuated downstream, within the separation zone. Pulsed-blowing VGJs at the upstream blade wall position were then actuated at various pulsing frequencies, duty cycles, and blowing ratios. These condition variations yielded differing levels of separation zone mitigation. Pulsed VGJs were shown to be more effective than steady blowing VGJs at conditions of high blowing ratio, high frequency, or high duty cycle, where blowing ratio had the highest level of influence on pulsed jet efficacy. The characteristic "calm zone" following the end of a given VGJ pulse was observed in simulations exhibiting high levels of separation zone mitigation. Numerical velocity fields near the blade wall during this calm zone was shown to be similar to velocity fields observed in PIV data. Instantaneous numerical vorticity fields indicated

  5. The calculation of molecular Eigen-frequencies

    NASA Technical Reports Server (NTRS)

    Lindemann, F. A.

    1984-01-01

    A method of determining molecular eigen-frequencies based on the function of Einstein expressing the variation of the atomic heat of various elements is proposed. It is shown that the same equation can be utilized to calculate both atomic heat and optically identifiably eigen-frequencies - at least to an order of magnitude - suggesting that in both cases the same oscillating structure is responsible.

  6. SULFIDE METHOD PLUTONIUM SEPARATION

    DOEpatents

    Duffield, R.B.

    1958-08-12

    A process is described for the recovery of plutonium from neutron irradiated uranium solutions. Such a solution is first treated with a soluble sullide, causing precipitation of the plutoniunn and uraniunn values present, along with those impurities which form insoluble sulfides. The precipitate is then treated with a solution of carbonate ions, which will dissolve the uranium and plutonium present while the fission product sulfides remain unaffected. After separation from the residue, this solution may then be treated by any of the usual methods, such as formation of a lanthanum fluoride precipitate, to effect separation of plutoniunn from uranium.

  7. Gas separation membranes

    DOEpatents

    Schell, William J.

    1979-01-01

    A dry, fabric supported, polymeric gas separation membrane, such as cellulose acetate, is prepared by casting a solution of the polymer onto a shrinkable fabric preferably formed of synthetic polymers such as polyester or polyamide filaments before washing, stretching or calendering (so called griege goods). The supported membrane is then subjected to gelling, annealing, and drying by solvent exchange. During the processing steps, both the fabric support and the membrane shrink a preselected, controlled amount which prevents curling, wrinkling or cracking of the membrane in flat form or when spirally wound into a gas separation element.

  8. Multistage Electrophoretic Separators

    NASA Technical Reports Server (NTRS)

    Thomas, Nathan; Doyle, John F.; Kurk, Andy; Vellinger, John C.; Todd, Paul

    2006-01-01

    A multistage electrophoresis apparatus has been invented for use in the separation of cells, protein molecules, and other particles and solutes in concentrated aqueous solutions and suspensions. The design exploits free electrophoresis but overcomes the deficiencies of prior free-electrophoretic separators by incorporating a combination of published advances in mathematical modeling of convection, sedimentation, electro-osmotic flow, and the sedimentation and aggregation of droplets. In comparison with other electrophoretic separators, these apparatuses are easier to use and are better suited to separation in relatively large quantities characterized in the art as preparative (in contradistinction to smaller quantities characterized in the art as analytical). In a multistage electrophoretic separator according to the invention, an applied vertical steady electric field draws the electrically charged particles of interest from within a cuvette to within a collection cavity that has been moved into position of the cuvette. There are multiple collection cavities arranged in a circle; each is aligned with the cuvette for a prescribed short time. The multistage, short-migration-path character of the invention solves, possibly for the first time, the fluid-instability problems associated with free electrophoresis. The figure shows a prototype multistage electrophoretic separator that includes four sample stations and five collection stages per sample. At each sample station, an aqueous solution or suspension containing charged species to be separated is loaded into a cuvette, which is machined into a top plate. The apparatus includes a lower plate, into which 20 collection cavities have been milled. Each cavity is filled with an electrophoresis buffer solution. For the collection of an electrophoretic fraction, the lower plate is rotated to move a designated collection cavity into alignment with the opening of the cuvette. An electric field is then applied between a non

  9. WET FLUORIDE SEPARATION METHOD

    DOEpatents

    Seaborg, G.T.; Gofman, J.W.; Stoughton, R.W.

    1958-11-25

    The separation of U/sup 233/ from thorium, protactinium, and fission products present in neutron-irradiated thorium is accomplished by dissolving the irradiated materials in aqueous nitric acid, adding either a soluble fluoride, iodate, phosphate, or oxalate to precipltate the thorium, separating the precipltate from the solution, and then precipitating uranlum and protactinium by alkalizing the solution. The uranium and protactinium precipitate is removcd from the solution and dissolved in nitric acid. The uranyl nitrate may then be extracted from the acid solution by means of ether, and the protactinium recovered from the aqueous phase.

  10. Separators for electrochemical cells

    SciTech Connect

    Carlson, Steven Allen; Anakor, Ifenna Kingsley

    2014-11-11

    Provided are separators for use in an electrochemical cell comprising (a) an inorganic oxide and (b) an organic polymer, wherein the inorganic oxide comprises organic substituents. Preferably, the inorganic oxide comprises an hydrated aluminum oxide of the formula Al.sub.2O.sub.3.xH.sub.2O, wherein x is less than 1.0, and wherein the hydrated aluminum oxide comprises organic substituents, preferably comprising a reaction product of a multifunctional monomer and/or organic carbonate with an aluminum oxide, such as pseudo-boehmite and an aluminum oxide. Also provided are electrochemical cells comprising such separators.

  11. Spiral fluid separator

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A. (Inventor)

    1993-01-01

    A fluid separator for separating particulate matter such as contaminates is provided which includes a series of spiral tubes of progressively decreasing cross sectional area connected in series. Each tube has an outlet on the outer curvature of the spiral. As fluid spirals down a tube, centrifugal force acts to force the heavier particulate matter to the outer wall of the tube, where it exits through the outlet. The remaining, and now cleaner, fluid reaches the next tube, which is smaller in cross sectional area, where the process is repeated. The fluid which comes out the final tube is diminished of particulate matter.

  12. Separation membrane development

    SciTech Connect

    Lee, M.W.

    1998-08-01

    A ceramic membrane has been developed to separate hydrogen from other gases. The method used is a sol-gel process. A thin layer of dense ceramic material is coated on a coarse ceramic filter substrate. The pore size distribution in the thin layer is controlled by a densification of the coating materials by heat treatment. The membrane has been tested by permeation measurement of the hydrogen and other gases. Selectivity of the membrane has been achieved to separate hydrogen from carbon monoxide. The permeation rate of hydrogen through the ceramic membrane was about 20 times larger than Pd-Ag membrane.

  13. SEPARATION OF FLUID MIXTURES

    DOEpatents

    Lipscomb, R.; Craig, A.; Labrow, S.; Dunn, J.F.

    1958-10-28

    An apparatus is presented for separating gaseous mixtures by selectively freezing a constituent of the mixture and subsequently separating the frozen gas. The gas mixture is passed through a cylinder fltted with a cooling jacket, causing one gas to freeze on the walls of the cylinder. A set of scraper blades are provided in the interior of the cyllnder, and as the blades oscillate, the frozen gas is scraped to the bottom of the cylinder. Means are provided for the frozen material to pass into a heating chamber where it is vaporized and the product gas collected.

  14. Polyvinyl alcohol membranes as alkaline battery separators

    NASA Technical Reports Server (NTRS)

    Sheibley, D. W.; Gonzalez-Sanabria, O.; Manzo, M. A.

    1982-01-01

    Polyvinly alcohol (PVA) cross-linked with aldehyde reagents yields membranes that demonstrate properties that make them suitable for use as alkaline battery separators. Film properties can be controlled by the choice of cross-linker, cross-link density and the method of cross-linking. Three methods of cross-linking and their effects on film properties are discussed. Film properties can also be modified by using a copolymer of vinyl alcohol and acrylic acid as the base for the separator and cross-linking it similarly to the PVA. Fillers can be incorporated into the films to further modify film properties. Results of separator screening tests and cell tests for several variations of PBA films are discussed.

  15. Nonaxisymmetric Variations Deep in the Convection Zone

    NASA Technical Reports Server (NTRS)

    Duvall, Thomas

    2002-01-01

    Using a deep-focusing time-distance technique and the MDI medium-1 data, a preliminary study of nonaxisymmetric variability deep in the convection zone has been performed. The purpose of the present study is to see what signals might be present in raw travel times indicating variation. To this end, noise levels will be examined. Correlations with point separations in the range 40-50 deg. have been measured for the entire medium-1 dataset over a significant fraction of the solar disk. Both flows and mean-time variations have been examined. Separation of near-surface signals from deep signals will also be examined.

  16. Time-frequency analysis of the bistatic acoustic scattering from a spherical elastic shell.

    PubMed

    Anderson, Shaun D; Sabra, Karim G; Zakharia, Manell E; Sessarego, Jean-Pierre

    2012-01-01

    The development of low-frequency sonar systems, using, for instance, a network of autonomous systems in unmanned vehicles, provides a practical means for bistatic measurements (i.e., when the source and receiver are widely separated) allowing for multiple viewpoints of the target of interest. Time-frequency analysis, in particular, Wigner-Ville analysis, takes advantage of the evolution time dependent aspect of the echo spectrum to differentiate a man-made target, such as an elastic spherical shell, from a natural object of the similar shape. A key energetic feature of fluid-loaded and thin spherical shell is the coincidence pattern, also referred to as the mid-frequency enhancement (MFE), that results from antisymmetric Lamb-waves propagating around the circumference of the shell. This article investigates numerically the bistatic variations of the MFE with respect to the monostatic configuration using the Wigner-Ville analysis. The observed time-frequency shifts of the MFE are modeled using a previously derived quantitative ray theory by Zhang et al. [J. Acoust. Soc. Am. 91, 1862-1874 (1993)] for spherical shell's scattering. Additionally, the advantage of an optimal array beamformer, based on joint time delays and frequency shifts is illustrated for enhancing the detection of the MFE recorded across a bistatic receiver array when compared to a conventional time-delay beamformer.

  17. [Geographic variations in freshwater molluscs].

    PubMed

    Vinarskiĭ, M V

    2012-01-01

    The phenomenon of geographic variation is known in practically all taxa of living beings. However, the reality of this phenomenon in freshwater molluscs (snails and bivalves) has many times been questioned in the past. It was accepted that these animals do not demonstrate spatially-oriented variation, where specific "local race" is arisen in each specific habitat. Till the beginning of 1970s, there was no statistical evidence that geographic clines in freshwater molluscs really exist. However, a few species of freshwater molluscs has been studied in this respect so far, therefore it is almost impossible to draw any general patterns of geographical variation in this group of animals. Most species of freshwater molluscs studied to the date exhibit statistically significant decrease of their body size in the south-north direction. Perhaps, it may be explained by decrease of the duration of the growth season in high latitudes. Some species of freshwater snails demonstrate clinal changes in shell proportions. This allows to reject subspecies separation within these species since diagnostic characters of such "subspecies" may blur when geographic variation is taken into consideration. The data on geographic variation in anatomical traits in freshwater molluscs is much more scarce. At least one species of pond snails (Lymnaea terebra) demonstrates clinal variation in proportions of the copulative apparatus in the south-north direction. Further studies of geographic variation in freshwater molluscs should reveal whether it is truly adaptive, i.e. whether geographical clines have underlying genetic basis. Otherwise, the clines may arise as a result of direct modifying effect of a habitat.

  18. Quantum teleportation in space and frequency using entangled pairs of photons from a frequency comb

    NASA Astrophysics Data System (ADS)

    Song, Hongbin; Yonezawa, Hidehiro; Kuntz, Katanya B.; Heurs, Michele; Huntington, Elanor H.

    2014-10-01

    Using entangled pairs of photons from a frequency comb and wide-band frequency-resolved homodyne detection, we propose a sequential quantum teleportation protocol for continuous variables that teleports an unknown state in space and frequency. A subthreshold optical parametric oscillator (OPO) produces a comb of entangled pairs of photons separated by the free spectral range of the OPO cavity. Wide-band frequency-resolved homodyne detection enables direct access to the sum and difference of quadratures between different teeth in the comb. Such measurements are Einstein-Podolsky-Rosen nullifiers, and can be used as the basis for teleportation protocols. Our protocol for space-and-frequency teleportation effectively links arbitrary frequency channels for frequency-division multiplexing, which has applications in universal quantum computation and large-capacity quantum communication.

  19. Round-Trip System Available to Measure Path Length Variation in Korea VLBI System for Geodesy

    NASA Technical Reports Server (NTRS)

    Oh, Hongjong; Kondo, Tetsuro; Lee, Jinoo; Kim, Tuhwan; Kim, Myungho; Kim, Suchul; Park, Jinsik; Ju, Hyunhee

    2010-01-01

    The construction project of Korea Geodetic VLBI officially started in October 2008. The construction of all systems will be completed by the end of 2011. The project was named Korea VLBI system for Geodesy (KVG), and its main purpose is to maintain the Korea Geodetic Datum. In case of the KVG system, an observation room with an H-maser frequency standard is located in a building separated from the antenna by several tens of meters. Therefore KVG system will adopt a so-called round-trip system to transmit reference signals to the antenna with reduction of the effect of path length variations. KVG s round-trip system is designed not only to use either metal or optical fiber cables, but also to measure path length variations directly. We present this unique round trip system for KVG.

  20. Neandertal origin of genetic variation at the cluster of OAS immunity genes.

    PubMed

    Mendez, Fernando L; Watkins, Joseph C; Hammer, Michael F

    2013-04-01

    Analyses of ancient DNA from extinct humans reveal signals of at least two independent hybridization events in the history of non-African populations. To date, there are very few examples of specific genetic variants that have been rigorously identified as introgressive. Here, we survey DNA sequence variation in the OAS gene cluster on chromosome 12 and provide strong evidence that a haplotype extending for ~185 kb introgressed from Neandertals. This haplotype is nearly restricted to Eurasians and is estimated to have diverged from the Neandertal sequence ~125 kya. Despite the potential for novel functional variation, the observed frequency of this haplotype is consistent with neutral introgression. This is the second locus in the human genome, after STAT2, carrying distinct haplotypes that appear to have introgressed separately from both Neandertals and Denisova. PMID:23315957

  1. Gas-separation process

    DOEpatents

    Toy, L.G.; Pinnau, I.; Baker, R.W.

    1994-01-25

    A process is described for separating condensable organic components from gas streams. The process makes use of a membrane made from a polymer material that is glassy and that has an unusually high free volume within the polymer material. 6 figures.

  2. NEAMS safeguards and separations

    SciTech Connect

    Sadasivan, Pratap; De Paoli, David W

    2011-01-25

    This presentation provides a program management update on the Safeguards and Separations Integrated Performance and Safety Code (IPSC) program in the DOE Nuclear Energy Advanced Modeling and Simulation (NEAMS). It provides an overview of FY11 work packages at multiple DOE Labs and includes material on challenge problem definitions for the IPSC effort.

  3. Separated Fringe Packet Binaries

    NASA Astrophysics Data System (ADS)

    Bagnuolo, W. G.; Taylor, S. F.; McAlister, H. A.; ten Brummelaar, T.; Sturmann, L.; Sturmann, J.; Turner, N. H.; Berger, D.; Ridgway, S. T.; CenterHigh Angular Resolution Astronomy (CHARA)

    2004-12-01

    Individually resolved packets are produced by scans from the CHARA Interferometer Array for binary stars with separations from 10 to 100 milli-arcsec (mas) in the K' band. We have used this data for astrometry of the binary with the goal of improving the visual orbits for these systems. About 12 data sets of 400 scans each can be collected for a star within an hour. The intrinsic accuracy with simple linear/quadratic fits to the time-separation curve yields accuracies of 0.15 mas. But, for systems with separations less than 80 mas, the measured separation is modulated periodically by the secondary star's packet riding over the sidelobes of the primary which provides a phase reference. This "sidelobe verniering" can improve the precision to better than 50 micro-arcsec. These techniques, represents 1-2 orders of magnitude improvement in astrometic accuracy over speckle interferometry techniques. Visual orbits can then be refined via a maximum liklihood technique, which leads to revisions in the stellar masses. We present the results for several binaries that have been observed at the CHARA Array, starting in 2001.

  4. Impedances of Tevatron separators

    SciTech Connect

    K. Y. Ng

    2003-05-28

    The impedances of the Tevatron separators are revisited and are found to be negligibly small in the few hundred MHz region, except for resonances at 22.5 MHz. The later are contributions from the power cables which may drive head-tail instabilities if the bunch is long enough.

  5. Alkaline battery, separator therefore

    NASA Technical Reports Server (NTRS)

    Schmidt, George F. (Inventor)

    1980-01-01

    An improved battery separator for alkaline battery cells has low resistance to electrolyte ion transfer and high resistance to electrode ion transfer. The separator is formed by applying an improved coating to an electrolyte absorber. The absorber, preferably, is a flexible, fibrous, and porous substrate that is resistant to strong alkali and oxidation. The coating composition includes an admixture of a polymeric binder, a hydrolyzable polymeric ester and inert fillers. The coating composition is substantially free of reactive fillers and plasticizers commonly employed as porosity promoting agents in separator coatings. When the separator is immersed in electrolyte, the polymeric ester of the film coating reacts with the electrolyte forming a salt and an alcohol. The alcohol goes into solution with the electrolyte while the salt imbibes electrolyte into the coating composition. When the salt is formed, it expands the polymeric chains of the binder to provide a film coating substantially permeable to electrolyte ion transfer but relatively impermeable to electrode ion transfer during use.

  6. Hydrogen isotope separation

    DOEpatents

    Bartlit, J.R.; Denton, W.H.; Sherman, R.H.

    Disclosed is a system of four cryogenic fractional distillation columns interlinked with two equilibrators for separating a DT and hydrogen feed stream into four product streams, consisting of a stream of high purity D/sub 2/, DT, T/sub 2/, and a tritium-free stream of HD for waste disposal.

  7. Hydrogen isotope separation

    DOEpatents

    Bartlit, John R.; Denton, William H.; Sherman, Robert H.

    1982-01-01

    A system of four cryogenic fractional distillation columns interlinked with two equilibrators for separating a DT and hydrogen feed stream into four product streams, consisting of a stream of high purity D.sub.2, DT, T.sub.2, and a tritium-free stream of HD for waste disposal.

  8. Separation and Attachment

    ERIC Educational Resources Information Center

    Honig, Alice Sterling

    2005-01-01

    Developing secure attachments with babies gives them a very special gift--the foundation for good infant mental health! In this article, the author discusses how to develop secure attachments with babies. Babies who are in the care of others during the day often suffer from separations from their special adults. Thirteen "tips" to ensure that…

  9. Polymide gas separation membranes

    DOEpatents

    Ding, Yong; Bikson, Benjamin; Nelson, Joyce Katz

    2004-09-14

    Soluble polyamic acid salt (PAAS) precursors comprised of tertiary and quaternary amines, ammonium cations, sulfonium cations, or phosphonium cations, are prepared and fabricated into membranes that are subsequently imidized and converted into rigid-rod polyimide articles, such as membranes with desirable gas separation properties. A method of enhancing solubility of PAAS polymers in alcohols is also disclosed.

  10. Separation of Powers.

    ERIC Educational Resources Information Center

    Bill of Rights in Action, 1987

    1987-01-01

    The dimensions of the separation of powers principle are explored through three lessons in the subject areas of U.S. history, U.S. government, and world history. In 1748, a French nobleman, Baron de Montesquieu, wrote a book called "The Spirit of the Laws," in which he argued that there could be no liberty when all government power was held by one…

  11. METHOD OF SEPARATING NEPTUNIUM

    DOEpatents

    Seaborg, G.T.

    1961-10-24

    plutonium in an aqueous solution containing sulfate ions. The process consists of contacting the solution with an alkali metal bromate, digesting the resulting mixture at 15 to 25 deg C for a period of time not more than that required to oxidize the neptunium, adding lanthanum ions and fluoride ions, and separating the plutonium-containing precipitate thus formed from the supernatant solution. (AEC)

  12. Separation, Separatism and Diversity.

    ERIC Educational Resources Information Center

    Hasegawa, Maya

    1991-01-01

    In the United States, once legal integration was achieved and the White male culture was challenged for real power, minority groups began to question the wisdom of cultural and social integration and celebrate diversity. An acceptable line between healthy separation and unhealthy separatism must be found. (MSE)

  13. Fathering After Marital Separation

    ERIC Educational Resources Information Center

    Keshet, Harry Finkelstein; Rosenthal, Kristine M.

    1978-01-01

    Deals with experiences of a group of separated or divorced fathers who chose to remain fully involved in the upbringing of their children. As they underwent transition from married parenthood to single fatherhood, these men learned that meeting demands of child care contributed to personal stability and growth. (Author)

  14. SEPARATION BY ADSORPTION

    DOEpatents

    Lowe, C.S.

    1959-06-16

    Separation of Pu from fission products by adsorption on hydrous aluminum silicate is described. The Pu in a HNO/sub 3/ solution is oxidized to the hexavalent state and contacted with the silicate which adsorbs fission products. (T.R.H.)

  15. Chemotactic separation of enzymes.

    PubMed

    Dey, Krishna Kanti; Das, Sambeeta; Poyton, Matthew F; Sengupta, Samudra; Butler, Peter J; Cremer, Paul S; Sen, Ayusman

    2014-12-23

    We demonstrate a procedure for the separation of enzymes based on their chemotactic response toward an imposed substrate concentration gradient. The separation is observed within a two-inlet, five-outlet microfluidic network, designed to allow mixtures of active (ones that catalyze substrate turnover) and inactive (ones that do not catalyze substrate turnover) enzymes, labeled with different fluorophores, to flow through one of the inlets. Substrate solution prepared in phosphate buffer was introduced through the other inlet of the device at the same flow rate. The steady-state concentration profiles of the enzymes were obtained at specific positions within the outlets of the microchannel using fluorescence microscopy. In the presence of a substrate concentration gradient, active enzyme molecules migrated preferentially toward the substrate channel. The excess migration of the active enzyme molecules was quantified in terms of an enrichment coefficient. Experiments were carried out with different pairs of enzymes. Coupling the physics of laminar flow of liquid and molecular diffusion, multiphysics simulations were carried out to estimate the extent of the chemotactic separation. Our results show that, with appropriate microfluidic arrangement, molecular chemotaxis leads to spontaneous separation of active enzyme molecules from their inactive counterparts of similar charge and size.

  16. Molten salt electrolyte separator

    DOEpatents

    Kaun, T.D.

    1996-07-09

    The patent describes a molten salt electrolyte/separator for battery and related electrochemical systems including a molten electrolyte composition and an electrically insulating solid salt dispersed therein, to provide improved performance at higher current densities and alternate designs through ease of fabrication. 5 figs.

  17. Lunar Soil Particle Separator

    NASA Technical Reports Server (NTRS)

    Berggren, Mark

    2010-01-01

    The Lunar Soil Particle Separator (LSPS) beneficiates soil prior to in situ resource utilization (ISRU). It can improve ISRU oxygen yield by boosting the concentration of ilmenite, or other iron-oxide-bearing materials found in lunar soils, which can substantially reduce hydrogen reduction reactor size, as well as drastically decreasing the power input required for soil heating

  18. Spousal-residence separation among Chinese young couples.

    PubMed

    Ma, Z; Liaw K-l; Zeng, Y

    1996-05-01

    The factors affecting the residential separation of spouses in China are examined. "Based on the microdata of the 1987 National Population Survey, we find that the variation in spousal-residence separations among Chinese young couples in the mid-1980s is well explained by personal and household factors within a multivariate model. The separations were aggravated by migrations for the reasons of employment or education. Although marriage migrations reduced the number of separations, those who had been married for a short period of time...were more prone to be separated. It is ironic that the higher a person's level of education, the greater the tendency for them to suffer the pain of spousal-residence separation. Household status could also be a very important factor: the lower the household status of a married individual, the more likely that he (or she) would be separated from their spouse."

  19. Separation science and technology

    SciTech Connect

    Smith, B.F.; Sauer, N.; Chamberlin, R.M.; Gottesfeld, S.; Mattes, B.R.; Li, D.Q.; Swanson, B.

    1998-12-31

    The focus of this project is the demonstration and advancement of membrane-based separation and destruction technologies. The authors are exploring development of membrane systems for gas separations, selective metal ion recovery, and for separation or destruction of hazardous organics. They evaluated existing polymers and polymer formulations for recovery of toxic oxyanionic metals such as chromate and arsenate from selected waste streams and developed second-generation water-soluble polymeric systems for highly selective oxyanion removal and recovery. They optimized the simultaneous removal of radioactive strontium and cesium from aqueous solutions using the new nonhazardous separations agents, and developed recyclable, redox-active extractants that permitted recovery of the radioactive ions into a minimal waste volume. They produced hollow fibers and fabricated prototype hollow-fiber membrane modules for applications to gas separations and the liquid-liquid extraction and recovery of actinides and nuclear materials from process streams. They developed and fabricated cyclodextrin-based microporous materials that selectively absorb organic compounds in an aqueous environment; the resultant products gave pure water with organics at less than 0.05 parts per billion. They developed new, more efficient, membrane-based electrochemical reactors for use in organic destruction in process waste treatment. They addressed the need for advanced oxidation technologies based on molecular-level materials designs that selectively remove or destroy target species. They prepared and characterized surface-modified TiO{sub 2} thin films using different linking approaches to attach ruthenium photosensitizers, and they started the measurement of the photo-degradation products generated using surface modified TiO{sub 2} films in reaction with chlorophenol.

  20. Partial differential equation transform — Variational formulation and Fourier analysis

    PubMed Central

    Wang, Yang; Wei, Guo-Wei; Yang, Siyang

    2011-01-01

    Nonlinear partial differential equation (PDE) models are established approaches for image/signal processing, data analysis and surface construction. Most previous geometric PDEs are utilized as low-pass filters which give rise to image trend information. In an earlier work, we introduced mode decomposition evolution equations (MoDEEs), which behave like high-pass filters and are able to systematically provide intrinsic mode functions (IMFs) of signals and images. Due to their tunable time-frequency localization and perfect reconstruction, the operation of MoDEEs is called a PDE transform. By appropriate selection of PDE transform parameters, we can tune IMFs into trends, edges, textures, noise etc., which can be further utilized in the secondary processing for various purposes. This work introduces the variational formulation, performs the Fourier analysis, and conducts biomedical and biological applications of the proposed PDE transform. The variational formulation offers an algorithm to incorporate two image functions and two sets of low-pass PDE operators in the total energy functional. Two low-pass PDE operators have different signs, leading to energy disparity, while a coupling term, acting as a relative fidelity of two image functions, is introduced to reduce the disparity of two energy components. We construct variational PDE transforms by using Euler-Lagrange equation and artificial time propagation. Fourier analysis of a simplified PDE transform is presented to shed light on the filter properties of high order PDE transforms. Such an analysis also offers insight on the parameter selection of the PDE transform. The proposed PDE transform algorithm is validated by numerous benchmark tests. In one selected challenging example, we illustrate the ability of PDE transform to separate two adjacent frequencies of sin(x) and sin(1.1x). Such an ability is due to PDE transform’s controllable frequency localization obtained by adjusting the order of PDEs. The