Science.gov

Sample records for short revisit time

  1. The late-time afterglow of the extremely energetic short burst GRB 090510 revisited

    NASA Astrophysics Data System (ADS)

    Nicuesa Guelbenzu, A.; Klose, S.; Krühler, T.; Greiner, J.; Rossi, A.; Kann, D. A.; Olivares, F.; Rau, A.; Afonso, P. M. J.; Elliott, J.; Filgas, R.; Küpcü Yolda?, A.; McBreen, S.; Nardini, M.; Schady, P.; Schmidl, S.; Sudilovsky, V.; Updike, A. C.; Yolda?, A.

    2012-02-01

    Context. The Swift discovery of the short burst GRB 090510 has raised considerable attention mainly because of two reasons: first, it had a bright optical afterglow, and second it is among the most energetic events detected so far within the entire GRB population (long plus short). The afterglow of GRB 090510 was observed with Swift/UVOT and Swift/XRT and evidence of a jet break around 1.5 ks after the burst has been reported in the literature, implying that after this break the optical and X-ray light curve should fade with the same decay slope. Aims: As noted by several authors, the post-break decay slope seen in the UVOT data is much shallower than the steep decay in the X-ray band, pointing to a (theoretically hard to understand) excess of optical flux at late times. We assess here the validity of this peculiar behavior. Methods: We reduced and analyzed new afterglow light-curve data obtained with the multichannel imager GROND. These additional g'r'i'z' data were then combined with the UVOT and XRT data to study the behavior of the afterglow at late times more stringently. Results: Based on the densely sampled data set obtained with GROND, we find that the optical afterglow of GRB 090510 did indeed enter a steep decay phase starting around 22 ks after the burst. During this time the GROND optical light curve is achromatic, and its slope is identical to the slope of the X-ray data. In combination with the UVOT data this implies that a second break must have occurred in the optical light curve around 22 ks post burst, which, however, has no obvious counterpart in the X-ray band, contradicting the interpretation that this could be another jet break. Conclusions: The GROND data provide the missing piece of evidence that the optical afterglow of GRB 090510 did follow a post-jet break evolution at late times. The break seen in the optical light curve around 22 ks in combination with its missing counterpart in the X-ray band could be due to the passage of the injection frequency across the optical bands, as already theoretically proposed in the literature. This is possibly the first time that this passage has been clearly seen in an optical afterglow. In addition, our results imply that there is no more evidence for an excess of flux in the optical bands at late times. Appendix A is available in electronic form at http://www.aanda.org

  2. The Late-time Afterglow of the Extremely Energetic Short Burst GRB 090510 Revisited

    NASA Technical Reports Server (NTRS)

    Guelbenzu, A. Nicuesa; Klose, S.; Kruehler, T.; Greiner, J.; Rossi, A.; Kann, D. A.; Olivares, F.; Rau, A.; Afonso, P. M. J.; Elliott, J.; Filgas, R.; Yoldas, A. Kuepcue; McBreen, S.; Nardini, M.; Schady, P.; Schmidl, S.; Sudilovsky, V.; Updike, A. C.; Yoldas, A.

    2012-01-01

    Context. The Swift discovery of the short burst GRB 090510 has raised considerable attention mainly because of two reasons: first, it had a bright optical afterglow, and second it is among the most energetic events detected so far within the entire GRB population (long plus short). The afterglow of GRB 090510 was observed with Swift/UVOT and Swift/XRT and evidence of a jet break around 1.5 ks after the burst has been reported in the literature, implying that after this break the optical and X-ray light curve should fade with the same decay slope. Aims. As noted by several authors, the post-break decay slope seen in the UVOT data is much shallower than the steep decay in the X-ray band, pointing to a (theoretically hard to understand) excess of optical flux at late times. We assess here the validity of this peculiar behavior. Methods. We reduced and analyzed new afterglow light-curve data obtained with the multichannel imager GROND. These additional g'r'i'z' data were then combined with the UVOT and XRT data to study the behavior of the afterglow at late times more stringently. Results. Based on the densely sampled data set obtained with GROND, we find that the optical afterglow of GRB 090510 did indeed enter a steep decay phase starting around 22 ks after the burst. During this time the GROND optical light curve is achromatic, and its slope is identical to the slope of the X-ray data. In combination with the UVOT data this implies that a second break must have occurred in the optical light curve around 22 ks post burst, which, however, has no obvious counterpart in the X-ray band, contradicting the interpretation that this could be another jet break. Conclusions. The GROND data provide the missing piece of evidence that the optical afterglow of GRB 090510 did follow a post-jet break evolution at late times. The break seen in the optical light curve around 22 ks in combination with its missing counterpart in the X-ray band could be due to the passage of the injection frequency across the optical bands, as already theoretically proposed in the literature. This is possibly the first time that this passage has been clearly seen in an optical afterglow. In addition, our results imply that there is no more evidence for an excess of flux in the optical bands at late times.

  3. A short revisit to Kuo-Brown effective interactions

    NASA Astrophysics Data System (ADS)

    Wang, XiaoBao; Dong, GuoXiang

    2015-10-01

    This paper is a short revisit to Kuo-Brown effective interaction derived from the Hamada-Johnston nucleon-nucleon potential, done by Gerry Brown and Tom Kuo. This effective interaction, derived in year 1966, is the first attempt to describe nuclear structure properties from the free nucleon-nucleon potential. Nowadays much progress has been achieved for the effective interactions in shell model. We would compare the effective interactions obtained in the 1966 paper with up-to-date shell-model interactions in sd-shell and pf-shell model space. Recent knowledge of effective interactions on nuclear structure, can also be traced in the Kuo- Brown effective interaction, i.e., the universal roles of central and tensor forces, which reminds us that such discovery should be noticed much earlier.

  4. Short Communication Revisit on the evolutionary relationship between alternative splicing and

    E-print Network

    Gu, Xun

    Short Communication Revisit on the evolutionary relationship between alternative splicing and gene duplication Alternative splicing Copy number variation Exon­intron structure Gene duplications and alternative sophisticated hypothesis, invoking that less alternative splicing genes tend to be duplicated more frequently

  5. Short Communication: Earth is (mostly) flat, but mountains dominate global denudation: apportionment of the continental mass flux over millennial time scales, revisited

    NASA Astrophysics Data System (ADS)

    Willenbring, J. K.; Codilean, A. T.; Ferrier, K. L.; McElroy, B.; Kirchner, J. W.

    2014-01-01

    Carbon dioxide consumption by silicate mineral weathering and the subsequent precipitation of carbonate sediments sequesters CO2 over geologic timescales. The rate of this carbon sequestration is coupled to rates of continental erosion, which exposes fresh minerals to weathering. Steep mountain landscapes represent a small fraction of continental surfaces but contribute disproportionately to global erosion rates. However, the relative contributions of Earth's much vaster, but more slowly eroding, plains and hills remain the subject of debate. Recently, Willenbring et al. (2013) analyzed a compilation of denudation rates and topographic gradients and concluded that low-gradient regions dominate global denudation fluxes and silicate weathering rates. Here, we show that Willenbring et al. (2003) topographic and statistical analyses were subject to methodological errors that affected their conclusions. We correct these errors, and reanalyze their denudation rate and topographic data. In contrast to the results of Willenbring et al. (2013), we find that the denudation flux from the steepest 10% of continental topography nearly equals the flux from the other 90% of the continental surface combined. This new analysis implies global denudation fluxes of ∼23 Gt yr-1, roughly five times the value reported in Willenbring et al. (2013) and closer to previous estimates found elsewhere in the literature. Although low-gradient landscapes make up a small proportion of the global fluxes, they remain important because of the human reliance, and impact, on these vast areas.

  6. Revisiting time reversal and holography with spacetime transformations

    E-print Network

    Bacot, Vincent; Eddi, Antonin; Fink, Mathias; Fort, Emmanuel

    2015-01-01

    Wave control is usually performed by spatially engineering the properties of a medium. Because time and space play similar roles in wave propagation, manipulating time boundaries provides a complementary approach. Here, we experimentally demonstrate the relevance of this concept by introducing instantaneous time mirrors. We show with water waves that a sudden change of the effective gravity generates time-reversed waves that refocus at the source. We generalize this concept for all kinds of waves introducing a universal framework which explains the effect of any time disruption on wave propagation. We show that sudden changes of the medium properties generate instant wave sources that emerge instantaneously from the entire space at the time disruption. The time-reversed waves originate from these "Cauchy sources" which are the counterpart of Huygens virtual sources on a time boundary. It allows us to revisit the holographic method and introduce a new approach for wave control.

  7. Special Relativity and Time Travel Revisited

    E-print Network

    Akhila Raman

    2001-01-25

    In this paper, Lorentz Transformation(LT) is derived by an alternate method, using photon clocks, placed at the locations of the concerned events, which are initially synchronised using a light signal(Einstein synchrony). Then, it is shown that the second term in the time dilation equation of the LT, is the term responsible for time travel and further it is shown that this term arises merely due to non-simultaneous initial clock synchronisation and that this term does not correspond to any actual time elapsed while timing events, thus ruling out the possibility of time travel, from the framework of special relativity. It is also shown that only the first term in the time dilation equation of LT represents the true time dilation. In other words, it is argued that the time dilation equation of the LT, corresponds to the actual reading of the clock which is not necessarily the actual time elapsed while timing an event, the difference being attributed to the clock synchronisation mechanism.

  8. Principal Preparation--Revisited--Time Matters

    ERIC Educational Resources Information Center

    Gutmore, Daniel

    2015-01-01

    There has been both a historic and continuing interest in the preparation process for school administrators (principals and vice principals). Much of the literature has been critical of how school administrators are prepared (Achilles, 1991; Hale and Moorman, 2003; Levine, 2005; Hallinger and Lu, 2013). Although the length of time from graduation…

  9. Nonlinear time-series analysis revisited.

    PubMed

    Bradley, Elizabeth; Kantz, Holger

    2015-09-01

    In 1980 and 1981, two pioneering papers laid the foundation for what became known as nonlinear time-series analysis: the analysis of observed data-typically univariate-via dynamical systems theory. Based on the concept of state-space reconstruction, this set of methods allows us to compute characteristic quantities such as Lyapunov exponents and fractal dimensions, to predict the future course of the time series, and even to reconstruct the equations of motion in some cases. In practice, however, there are a number of issues that restrict the power of this approach: whether the signal accurately and thoroughly samples the dynamics, for instance, and whether it contains noise. Moreover, the numerical algorithms that we use to instantiate these ideas are not perfect; they involve approximations, scale parameters, and finite-precision arithmetic, among other things. Even so, nonlinear time-series analysis has been used to great advantage on thousands of real and synthetic data sets from a wide variety of systems ranging from roulette wheels to lasers to the human heart. Even in cases where the data do not meet the mathematical or algorithmic requirements to assure full topological conjugacy, the results of nonlinear time-series analysis can be helpful in understanding, characterizing, and predicting dynamical systems. PMID:26428563

  10. Nonlinear time-series analysis revisited

    NASA Astrophysics Data System (ADS)

    Bradley, Elizabeth; Kantz, Holger

    2015-09-01

    In 1980 and 1981, two pioneering papers laid the foundation for what became known as nonlinear time-series analysis: the analysis of observed data—typically univariate—via dynamical systems theory. Based on the concept of state-space reconstruction, this set of methods allows us to compute characteristic quantities such as Lyapunov exponents and fractal dimensions, to predict the future course of the time series, and even to reconstruct the equations of motion in some cases. In practice, however, there are a number of issues that restrict the power of this approach: whether the signal accurately and thoroughly samples the dynamics, for instance, and whether it contains noise. Moreover, the numerical algorithms that we use to instantiate these ideas are not perfect; they involve approximations, scale parameters, and finite-precision arithmetic, among other things. Even so, nonlinear time-series analysis has been used to great advantage on thousands of real and synthetic data sets from a wide variety of systems ranging from roulette wheels to lasers to the human heart. Even in cases where the data do not meet the mathematical or algorithmic requirements to assure full topological conjugacy, the results of nonlinear time-series analysis can be helpful in understanding, characterizing, and predicting dynamical systems.

  11. Nonlinear time-series analysis revisited

    E-print Network

    Elizabeth Bradley; Holger Kantz

    2015-03-25

    In 1980 and 1981, two pioneering papers laid the foundation for what became known as nonlinear time-series analysis: the analysis of observed data---typically univariate---via dynamical systems theory. Based on the concept of state-space reconstruction, this set of methods allows us to compute characteristic quantities such as Lyapunov exponents and fractal dimensions, to predict the future course of the time series, and even to reconstruct the equations of motion in some cases. In practice, however, there are a number of issues that restrict the power of this approach: whether the signal accurately and thoroughly samples the dynamics, for instance, and whether it contains noise. Moreover, the numerical algorithms that we use to instantiate these ideas are not perfect; they involve approximations, scale parameters, and finite-precision arithmetic, among other things. Even so, nonlinear time-series analysis has been used to great advantage on thousands of real and synthetic data sets from a wide variety of systems ranging from roulette wheels to lasers to the human heart. Even in cases where the data do not meet the mathematical or algorithmic requirements to assure full topological conjugacy, the results of nonlinear time-series analysis can be helpful in understanding, characterizing, and predicting dynamical systems.

  12. Revisiting algorithms for generating surrogate time series

    E-print Network

    C. Raeth; M. Gliozzi; I. E. Papadakis; W. Brinkmann

    2012-08-17

    The method of surrogates is one of the key concepts of nonlinear data analysis. Here, we demonstrate that commonly used algorithms for generating surrogates often fail to generate truly linear time series. Rather, they create surrogate realizations with Fourier phase correlations leading to non-detections of nonlinearities. We argue that reliable surrogates can only be generated, if one tests separately for static and dynamic nonlinearities.

  13. 0957 + 561 - The time delay revisited

    NASA Astrophysics Data System (ADS)

    Falco, E. E.; Shapiro, I. I.; Krolik, J. H.

    A reanalysis of Schild's (1986) data set (RS) and that of Vanderriest et al. (1989) (CV) is presented to consider the reliable determination of the difference in light propagation times from the source to the observer via A and B, delta-tau(BA). Three requirements for the accurate estimation of delta-tau(BA) are a statistically significant peak in cross-correlation, the statistical similarity of A and B in RS and CV, and the consideration of microlensing effects. The Edelson and Krolik (1988) method of discrete correlations is then applied to avoid interpolation of the time series and therefore possible biases. Any inference of delta-tau(BA) from the RS and CV optical flux data is shown to be unreliable due to the unevenness of the sampling and the possibility of systematic errors. If 0957 + 561 is not a lens system, one or both light curves may be affected microlensing, G1 may have varied over the sampling period, or unknown systematic effects may have reduced the quality of the measurements.

  14. Time to Revisit the Heterogeneous Telescope Network

    NASA Astrophysics Data System (ADS)

    Hessman, F. V.

    The "Heterogeneous Telescope Network" (HTN) was founded in 2005 as a loose collaboration of people somehow associated with robotic telescopes and/or projects interested in the transient universe. Other than being a very interesting forum for the exchange of ideas, the only lasting contribution of the HTN was a proposed protocol for the operation of a loose e-market for the exchange of telescope time (Allan et al. 2006; White & Allan 2007). Since the last formal meeting in 2007, the HTN has gone into a "Dornröschenschlaf" (a better word than "hibernation") : the players and interest are there, but the public visibility and activity is not. Although the participants knew and know that global networking is the way of the future for many types of science, various things have kept the HTN from taking the idea and actually implementing it: work on simply getting one's own system to work (e.g. myself), career paths of major players (e.g. Allan), dealing with the complexity of ones' own network (TALONS, RoboNet, LCO), and - most importantly - no common science driver big enough to push the participants to try it in earnest. Things have changed, however: robotic telescopes have become easier to create and operate, private networks have matured, large-scale consortia have become more common, event reporting using VOEvent has become the global standard and has a well-defined infrastructure, and large-scale sources of new objects and events are operating or will soon be operating (OGLE, CSS, Pan-STARRs, GAIA). I will review the scientific and sociological prospects for re-invigorating the HTN idea and invite discussion.

  15. Short Time Cycles of Purely Quantum Refrigerators

    E-print Network

    Feldmann, Tova

    2012-01-01

    Four stroke Otto refrigerator cycles with no classical analogue are studied. Extremely short cycle times with respect to the internal time scale of the working medium characterize these refrigerators. Therefore these cycles are termed sudden. The sudden cycles are characterized by the stable limit cycle which is the invariant of the global cycle propagator. During their operation the state of the working medium possesses significant coherence which is not erased in the equilibration segments due to the very short time allocated. This characteristic is reflected in a difference between the energy entropy and the Von Neumann entropy of the working medium. A classification scheme for sudden refrigerators is developed allowing simple approximations for the cooling power and coefficient of performance.

  16. Short Time Cycles of Purely Quantum Refrigerators

    E-print Network

    Tova Feldmann; Ronnie Kosloff

    2012-04-18

    Four stroke Otto refrigerator cycles with no classical analogue are studied. Extremely short cycle times with respect to the internal time scale of the working medium characterize these refrigerators. Therefore these cycles are termed sudden. The sudden cycles are characterized by the stable limit cycle which is the invariant of the global cycle propagator. During their operation the state of the working medium possesses significant coherence which is not erased in the equilibration segments due to the very short time allocated. This characteristic is reflected in a difference between the energy entropy and the Von Neumann entropy of the working medium. A classification scheme for sudden refrigerators is developed allowing simple approximations for the cooling power and coefficient of performance.

  17. Brownian motion at short time scales

    E-print Network

    Tongcang Li; Mark G. Raizen

    2012-11-07

    Brownian motion has played important roles in many different fields of science since its origin was first explained by Albert Einstein in 1905. Einstein's theory of Brownian motion, however, is only applicable at long time scales. At short time scales, Brownian motion of a suspended particle is not completely random, due to the inertia of the particle and the surrounding fluid. Moreover, the thermal force exerted on a particle suspended in a liquid is not a white noise, but is colored. Recent experimental developments in optical trapping and detection have made this new regime of Brownian motion accessible. This review summarizes related theories and recent experiments on Brownian motion at short time scales, with a focus on the measurement of the instantaneous velocity of a Brownian particle in a gas and the observation of the transition from ballistic to diffusive Brownian motion in a liquid.

  18. Short-time diffusivity of dicolloids

    NASA Astrophysics Data System (ADS)

    Panczyk, Mark M.; Wagner, Norman J.; Furst, Eric M.

    2014-06-01

    The short-time diffusivity of dicolloid particles as a function of particle volume fraction ? from 0.01???0.6 is measured using diffusing wave spectroscopy. The diffusivities of symmetric and asymmetric dicolloids are compared with similarly sized spheres. The short-time diffusivity is independent of salt concentration and decreases with increasing volume fraction for both spheres and asymmetric dicolloids. Symmetric dicolloids have a higher diffusivity than spheres at similar volume fractions. This difference is accounted for by rescaling the dicolloid volume fraction based on the ratio of the random close-packing volume fractions of spheres and dicolloids. Finally, a useful method is provided for calculating the diffusivity of symmetric dicolloid particles of arbitrary aspect ratio based on the calculated hydrodynamic resistance of Zabarankin [Proc. R. Soc. A 463, 2329 (2007), 10.1098/rspa.2007.1872].

  19. Short-time diffusivity of dicolloids.

    PubMed

    Panczyk, Mark M; Wagner, Norman J; Furst, Eric M

    2014-06-01

    The short-time diffusivity of dicolloid particles as a function of particle volume fraction ? from 0.01 ? ? ? 0.6 is measured using diffusing wave spectroscopy. The diffusivities of symmetric and asymmetric dicolloids are compared with similarly sized spheres. The short-time diffusivity is independent of salt concentration and decreases with increasing volume fraction for both spheres and asymmetric dicolloids. Symmetric dicolloids have a higher diffusivity than spheres at similar volume fractions. This difference is accounted for by rescaling the dicolloid volume fraction based on the ratio of the random close-packing volume fractions of spheres and dicolloids. Finally, a useful method is provided for calculating the diffusivity of symmetric dicolloid particles of arbitrary aspect ratio based on the calculated hydrodynamic resistance of Zabarankin [Proc. R. Soc. A 463, 2329 (2007)]. PMID:25019780

  20. Failure Prevention by Short Time Corrosion Tests

    SciTech Connect

    MICKALONIS, JOHN

    2005-05-01

    Short time corrosion testing of perforated sheets and wire meshes fabricated from Type 304L stainless steel, Alloy 600 and C276 showed that 304L stainless steel perforated sheet should perform well as the material of construction for dissolver baskets. The baskets will be exposed to hot nitric acid solutions and are limited life components. The corrosion rates of the other alloys and of wire meshes were too high for useful extended service. Test results also indicated that corrosion of the dissolver should drop quickly during the dissolutions due to the inhibiting effects of the corrosion products produced by the dissolution processes.

  1. DIVERGENCE TIMES AND THE EVOLUTION OF EPIPHYTISM IN FILMY FERNS (HYMENOPHYLLACEAE) REVISITED

    E-print Network

    DIVERGENCE TIMES AND THE EVOLUTION OF EPIPHYTISM IN FILMY FERNS (HYMENOPHYLLACEAE) REVISITED Sabine and Science, 4-1-1 Amakubo, Tsukuba 305-0005, Japan Although the phylogeny of the filmy fern family to examine the diversification of filmy ferns and the evolution of their ecology within a temporal context

  2. Hurst exponents for short time series

    NASA Astrophysics Data System (ADS)

    Qi, Jingchao; Yang, Huijie

    2011-12-01

    A concept called balanced estimator of diffusion entropy is proposed to detect quantitatively scalings in short time series. The effectiveness is verified by detecting successfully scaling properties for a large number of artificial fractional Brownian motions. Calculations show that this method can give reliable scalings for short time series with length ˜102. It is also used to detect scalings in the Shanghai Stock Index, five stock catalogs, and a total of 134 stocks collected from the Shanghai Stock Exchange Market. The scaling exponent for each catalog is significantly larger compared with that for the stocks included in the catalog. Selecting a window with size 650, the evolution of scaling for the Shanghai Stock Index is obtained by the window's sliding along the series. Global patterns in the evolutionary process are captured from the smoothed evolutionary curve. By comparing the patterns with the important event list in the history of the considered stock market, the evolution of scaling is matched with the stock index series. We can find that the important events fit very well with global transitions of the scaling behaviors.

  3. Biogas from Macroalgae: is it time to revisit the idea?

    PubMed Central

    2012-01-01

    The economic and environmental viability of dedicated terrestrial energy crops is in doubt. The production of large scale biomass (macroalgae) for biofuels in the marine environment was first tested in the late 1960’s. The culture attempts failed due to the engineering challenges of farming offshore. However the energy conversion via anaerobic digestion was successful as the biochemical composition of macroalgae makes it an ideal feedstock. The technology for the mass production of macroalgae has developed principally in China and Asia over the last 50 years to such a degree that it is now the single largest product of aquaculture. There has also been significant technology transfer and macroalgal cultivation is now well tried and tested in Europe and America. The inherent advantage of production of biofuel feedstock in the marine environment is that it does not compete with food production for land or fresh water. Here we revisit the idea of the large scale cultivation of macroalgae at sea for subsequent anaerobic digestion to produce biogas as a source of renewable energy, using a European case study as an example. PMID:23186536

  4. Sco X-1 revisited with Kepler, MAXI and HERMES: outflows, time-lags and echoes unveiled

    NASA Astrophysics Data System (ADS)

    Scaringi, S.; Maccarone, T. J.; Hynes, R. I.; Körding, E.; Ponti, G.; Knigge, C.; Britt, C. T.; van Winckel, H.

    2015-08-01

    Sco X-1 has been the subject of many multiwavelength studies in the past, being the brightest persistent extrasolar X-ray source ever observed. Here, we revisit Sco X-1 with simultaneous short cadence Kepler optical photometry and Monitor of All-sky X-ray Image X-ray photometry over a 78 d period, as well as optical spectroscopy obtained with High Efficiency and Resolution Mercator Echelle Spectrograph (HERMES). We find Sco X-1 to be highly variable in all our data sets. The optical fluxes are clearly bimodal, implying the system can be found in two distinct optical states. These states are generally associated with the known flaring/normal branch X-ray states, although the flux distributions associated with these states overlap. Furthermore, we find that the optical power spectrum of Sco X-1 differs substantially between optical luminosity states. Additionally we find rms-flux relations in both optical states, but only find a linear relation during periods of low optical luminosity. The full optical/X-ray discrete correlation function displays a broad ?12.5 h optical lag. However, during the normal branch phase, the X-ray and optical fluxes are anticorrelated, whilst being correlated during the flaring branch. We also performed a Cepstrum analysis on the full Kepler light curve to determine the presence of any echoes within the optical light curve alone. We find significant echo signals, consistent with the optical lags found using the discrete cross-correlation. We speculate that whilst some of the driving X-ray emission is reflected by the disc, some is absorbed and re-processed on the thermal time-scale, giving rise to both the observed optical lags and optical echoes.

  5. Rate Sheet Essential in Long and Short Time Farm Loans. 

    E-print Network

    Bennett, R. L.; Paris, M. S.

    1916-01-01

    and Mechanical College of Texas (in cooperation with the United States Department of Agriculture) OCTOBER 1916 EXTENSION SERVICE No. B-28 RATE SHEET ESSENTIAL IN LONG AND SHORT TIME FARM LOANS BY R. L. BENNETT, Paris Texas Address CLARENCE OUSLEY Director... of Extension Service, College Station, Texas. RATE SHEET ESSENTIAL IN LONG TIME AND SHORT TIME FARM LOANS. By R. L. Bennett, M. S., Paris, Texas. The Federal Reserve law provides for short time rural credit, and the Federal Land Loan Act provides for long time...

  6. Surgical time and motion: the intermediate equivalent revisited.

    PubMed Central

    Senapati, P. S. P.; Barry, J. D.; Edwards, P.; Hodzovic, I.; Shute, K.; Lewis, W. G.

    2003-01-01

    The relationship between operative time, the intermediate equivalent value (IEV) and the complexity of common general surgical operations was examined. Correlation was found between the BUPA schedule values for procedures categorized as intermediate and major, but complex major vascular reconstruction and oesophagogastric resection for cancer occupied significantly more theatre time than the four intermediate equivalents allocated by the Collins or BUPA schedule. Moreover, anaesthetic preparation time for complex major surgery in the latter surgical subspecialities contributed at least one further intermediate value. Re-evaluation of the ideal IEV weighting of all surgical operations including anaesthetic input from larger similar audits would allow more accurate audits of surgeons' work-load, and also facilitate transparent intensive management of operating theatre resource. PMID:12585631

  7. The multi-configurational time-dependent Hartree approach revisited

    NASA Astrophysics Data System (ADS)

    Manthe, Uwe

    2015-06-01

    The multi-configurational time-dependent Hartree (MCTDH) approach facilitates accurate high-dimensional quantum dynamics simulations. In the approach, the wavefunction is expanded in a direct product of self-adapting time-dependent single-particle functions (SPFs). The equations of motion for the expansion coefficients and the SPFs are obtained via the Dirac-Frenkel variational principle. While this derivation yields well-defined differential equations for the motion of occupied SPFs, singularities in the working equations resulting from unoccupied SPFs have to be removed by a regularization procedure. Here, an alternative derivation of the MCTDH equations of motion is presented. It employs an analysis of the time-dependence of the single-particle density matrices up to second order. While the analysis of the first order terms yields the known equations of motion for the occupied SPFs, the analysis of the second order terms provides new equations which allow one to identify optimal choices for the unoccupied SPFs. The effect of the optimal choice of the unoccupied SPFs on the structure of the MCTDH equations of motion and their regularization is discussed. Generalized equations applicable in the multi-layer MCTDH framework are presented. Finally, the effects resulting from the initial choice of the unoccupied SPFs are illustrated by a simple numerical example.

  8. Through the mists of time: Sushrutha, an enigma revisited

    PubMed Central

    Puthumana, Philip Philip

    2009-01-01

    Sushrutha had been viewed in textbooks of plastic surgery as belonging to the caste of potters who performed surgery in India. We have examined the available source documents and other references to the technology of the period to examine this assertion and are convinced that there is no evidence to support this. The period, technology and geographic references in Sushrutha Samhitha are correlated with settled positions on these to arrive at an understanding of the time and knowledge which is described. Source of erroneous interpretation of Sushrutha as a potter is also examined and clarified. PMID:20368861

  9. Revisiting the Central Dogma One Molecule at a Time

    PubMed Central

    Bustamante, Carlos; Cheng, Wei; Meija, Yara

    2011-01-01

    The faithful relay and timely expression of genetic information depend on specialized molecular machines, many of which function as nucleic acid translocases. The emergence over the last decade of single-molecule fluorescence detection and manipulation techniques with nm and Å resolution, and their application to the study of nucleic acid translocases are painting an increasingly sharp picture of the inner workings of these machines, the dynamics and coordination of their moving parts, their thermodynamic efficiency, and the nature of their transient intermediates. Here we present an overview of the main results arrived at by the application of single-molecule methods to the study of the main machines of the central dogma. PMID:21335233

  10. Controlled short residence time coal liquefaction process

    DOEpatents

    Anderson, Raymond P. (Overland Park, KS); Schmalzer, David K. (Englewood, CO); Wright, Charles H. (Overland Park, KS)

    1982-05-04

    Normally solid dissolved coal product and a distillate liquid product are produced by continuously passing a feed slurry comprising raw feed coal and a recycle solvent oil and/or slurry together with hydrogen to a preheating-reaction zone (26, alone, or 26 together with 42), the hydrogen pressure in the preheating-reaction zone being at least 1500 psig (105 kg/cm.sup.2), reacting the slurry in the preheating-reaction zone (26, or 26 with 42) at a temperature in the range of between about 455.degree. and about 500.degree. C. to dissolve the coal to form normally liquid coal and normally solid dissolved coal. A total slurry residence time is maintained in the reaction zone ranging from a finite value from about 0 to about 0.2 hour, and reaction effluent is continuously and directly contacted with a quenching fluid (40, 68) to substantially immediately reduce the temperature of the reaction effluent to below 425.degree. C. to substantially inhibit polymerization so that the yield of insoluble organic matter comprises less than 9 weight percent of said feed coal on a moisture-free basis. The reaction is performed under conditions of temperature, hydrogen pressure and residence time such that the quantity of distillate liquid boiling within the range C.sub.5 -455.degree. C. is an amount at least equal to that obtainable by performing the process under the same conditions except for a longer total slurry residence time, e.g., 0.3 hour. Solvent boiling range liquid is separated from the reaction effluent and recycled as process solvent.

  11. Nuclear Winter Revisited: can it Make a Difference This Time?

    NASA Astrophysics Data System (ADS)

    Schneider, S.

    2006-12-01

    Some 23 years ago, in the middle of a Cold War and the threat of a strategic nuclear weapons exchange between NATO and the Warsaw Pact nations, atmospheric scientists pointed out that the well-anticipated side effects of a large-scale nuclear war ozone depletion, radioactive contamination and some climatic effects had massively underestimated the more likely implications: massive fires, severe dimming and cooling beneath circulating smoke clouds, disruption to agriculture in non-combatant nations, severe loss of imports of food to already-food-deficient regions and major alterations to atmospheric circulation. While the specific consequences were dependent on both scenarios of weapons use and injections and removals of smoke and dust and other chemicals into the atmosphere, it was clear that this would be despite passionately argued uncertainties a large major additional effect. As further investigations of smoke removal, patchy transport, etc., were pursued, the basic concerns remained, but the magnitude calculated with one-dimensional models diminished creating an unfortunate media debate over nuclear winter vs. nuclear autumn. Of course, one can't grow summer crops in any autumn natural or nuclear but that concern often got lost in the contentious political debate. Of course, it was pointed out that anyone who required knowing the additional environmental consequences of a major nuclear exchange to be finally deterred was already so far from the reality of the direct effects of the blasts that they might never see the concerns. But for non-combatants, it was a major awakening of their inability to escape severe consequences of the troubles of others, even if they were bystanders in the east-west conflicts. Two decades later, things have radically changed: the prospect of a massive strategic nuclear exchange is greatly diminished good news but the possibility of limited regional exchanges or terrorist incidents is widely believed to have greatly increased bad news. Therefore, the re- examination in this AGU session of the entire subject of environmental and social after-effects of any nuclear weapons use is, unfortunately, once again timely. Hopefully it will convince anyone not already convinced based on conventional damages from nuclear weapons use of the urgent need to abate proliferation and monitor and control access to and potential capabilities of those who might contemplate using such weapons for some Strangelove-like strategic or ideological objective. The extent to which a scientific re-examination of the broader horrendous implications of any scale of use of nuclear weapons will deter those contemplating their use is questionable. However, it seems likely such research would increase the resolve of the large number of countries and institutions already pressing to prevent nuclear weapons use.

  12. Recent studies of short-range order in alloys: The Cowley theory revisited

    SciTech Connect

    Reinhard, L.; Moss, S.C.

    1993-02-08

    We present comparisons of various statistical theories for effective pair interactions (EPI) in alloys. We then evaluate these EPI`s using the Cowley theory, the Krivoglaz-Clapp-Moss (KCM) approximation, the {gamma}-expansion method (GEM) of Tokar, Masanskii and coworkers, and the exact inverse Monte Carlo (IMC) method, introduced by Gerold and Kern. Via a series of model calculations on a hypothetical bcc alloy with a single nearest-neighbor interaction we show that the Cowley theory is successful in evaluating the EPI`s in more dilute alloys but tends to overestimate the magnitude of the nearest neighbor energy at higher concentrations, whereas the KCM expression becomes increasingly inaccurate at lower concentrations. In general, however, the approximate mean field theories are most accurate at higher concentrations and higher temperatures. Recent studies of short-range order in single crystals are discussed in which these EPI`s have been evaluated using the IMC, KCM, GEM and Cowley theories. Examples include the bcc alloy Fe{sub 0.53}Cr{sub 0.47} and the fcc alloys Cu{sub 3} Au, CU{sub 0.69}Zn{sub 0.31} and Ni{sub 0.89}BgCr{sub 0.11}. In all cases the approximate expressions do quite well, especially the GEM.

  13. Short-term and long-term stability of surgically assisted rapid palatal expansion revisited

    PubMed Central

    Chamberland, Sylvain; Proffit, William R.

    2014-01-01

    Introduction The purpose of this article is to present further longitudinal data for short-term and long-term stability, following up our previous article in the surgery literature with a larger sample and 2 years of stability data. Methods Data from 38 patients enrolled in this prospective study were collected before treatment, at maximum expansion, at removal of the expander 6 months later, before any second surgical phase, at the end of orthodontic treatment, and at the 2-year follow-up, by using posteroanterior cephalograms and dental casts. Results With surgically assisted rapid palatal expansion (SARPE), the mean maximum expansion at the first molar was 7.60 ± 1.57 mm, and the mean relapse was 1.83 ± 1.83 mm (24%). Modest relapse after completion of treatment was not statistically significant for all teeth except for the maxillary first molar (0.99 ± 1.1 mm). A significant relationship (P <0.0001) was observed between the amount of relapse after SARPE and the posttreatment observation. At maximum, a skeletal expansion of 3.58 ± 1.63 mm was obtained, and this was stable. Conclusions Skeletal changes with SARPE were modest but stable. Relapse in dental expansion was almost totally attributed to lingual movement of the posterior teeth; 64% of the patients had more than 2 mm of dental changes. Phase 2 surgery did not affect dental relapse. PMID:21640889

  14. Speech processing based on short-time Fourier analysis

    SciTech Connect

    Portnoff, M.R.

    1981-06-02

    Short-time Fourier analysis (STFA) is a mathematical technique that represents nonstationary signals, such as speech, music, and seismic signals in terms of time-varying spectra. This representation provides a formalism for such intuitive notions as time-varying frequency components and pitch contours. Consequently, STFA is useful for speech analysis and speech processing. This paper shows that STFA provides a convenient technique for estimating and modifying certain perceptual parameters of speech. As an example of an application of STFA of speech, the problem of time-compression or expansion of speech, while preserving pitch and time-varying frequency content is presented.

  15. Revisited gauge principle: towards a unification of space-time and internal gauge interactions

    E-print Network

    V. Aldaya; J. L. Jaramillo; J. Guerrero

    2002-12-17

    The minimal coupling principle is revisited under the quantum perspectives of the space-time symmetry. This revision is better realized on a Group Approach to Quantization (GAQ) where group cohomology and extensions of groups play a preponderant role. We firstly consider the case of the electromagnetic potential; the Galilei and/or Poincare group is (non-centrally) extended by the "local" U(1) group. This group can also be seen as a central extension, parametrized by both the mass and the electric charge, of an infinite-dimensional group, on which GAQ leads to the dynamics of a particle moving in the presence of an electromagnetic field. Then we try the gravitational interaction of a particle by turning into "local" the space-time translations. However, promoting to "local" the space-time subgroup of the true symmetry of the quantum free relativistic particle, i.e. the centrally extended by U(1) Poincare group, results in a new electromagnetic-like force of pure gravitational origin. This is a consequence of the space-time translations not being an invariant subgroup of the extended Poincare group and constitutes a preliminary attempt to a non-trivial mixing of space-time and internal gauge interactions.

  16. Lithography cycle time improvements using short-interval scheduling

    NASA Astrophysics Data System (ADS)

    Norman, David; Watson, Scott; Anderson, Michael; Marteney, Steve; Mehr, Ben

    2010-04-01

    Partially and fully automated semiconductor manufacturing facilities around the world have employed automated real-time dispatchers (RTD) as a critical element of their factory management solutions. The success of RTD is attributable to a detailed and extremely accurate data base that reflects the current state of the factory, consistently applied dispatching policies and continuous improvement of these dispatching policies. However, many manufactures are now reaching the benefit limits of pure dispatching-based or other "heuristic-only" solutions. A new solution is needed that combines locally optimized short-interval schedules with RTD policies to target further reductions in product cycle time. This paper describes an integrated solution that employs four key components: 1. real-time data generation, 2. simulation-based prediction, 3. locally optimized short-interval scheduling, and 4. schedule-aware real-time dispatching. The authors describe how this solution was deployed in lithography and wet / diffusion areas, and report the resulting improvements measured.

  17. Measurement of hyperpolarized gas diffusion at very short time scales

    PubMed Central

    Carl, Michael; Wilson Miller, G.; Mugler, John P.; Rohrbaugh, Scott; Tobias, William A.; Cates, Gordon D.

    2007-01-01

    We present a new pulse sequence for measuring very-short-time-scale restricted diffusion of hyperpolarized noble gases. The pulse sequence is based on concatenating a large number of bipolar diffusion-sensitizing gradients to increase the diffusion attenuation of the MR signal while maintaining a fundamentally short diffusion time. However, it differs in several respects from existing methods that use oscillating diffusion gradients for this purpose. First, a wait time is inserted between neighboring pairs of gradient pulses; second, consecutive pulse pairs may be applied along orthogonal axes; and finally, the diffusion-attenuated signal is not simply read out at the end of the gradient train but is periodically sampled during the wait times between neighboring pulse pairs. The first two features minimize systematic differences between the measured (apparent) diffusion coefficient and the actual time-dependent diffusivity, while the third feature optimizes the use of the available MR signal to improve the precision of the diffusivity measurement in the face of noise. The benefits of this technique are demonstrated using theoretical calculations, Monte-Carlo simulations of gas diffusion in simple geometries, and experimental phantom measurements in a glass sphere containing hyperpolarized 3He gas. The advantages over the conventional single-bipolar approach were found to increase with decreasing diffusion time, and thus represent a significant step toward making accurate surface-to-volume measurements in the lung airspaces. PMID:17936048

  18. Evaluation of Scaling Invariance Embedded in Short Time Series

    PubMed Central

    Pan, Xue; Hou, Lei; Stephen, Mutua; Yang, Huijie; Zhu, Chenping

    2014-01-01

    Scaling invariance of time series has been making great contributions in diverse research fields. But how to evaluate scaling exponent from a real-world series is still an open problem. Finite length of time series may induce unacceptable fluctuation and bias to statistical quantities and consequent invalidation of currently used standard methods. In this paper a new concept called correlation-dependent balanced estimation of diffusion entropy is developed to evaluate scale-invariance in very short time series with length . Calculations with specified Hurst exponent values of show that by using the standard central moving average de-trending procedure this method can evaluate the scaling exponents for short time series with ignorable bias () and sharp confidential interval (standard deviation ). Considering the stride series from ten volunteers along an approximate oval path of a specified length, we observe that though the averages and deviations of scaling exponents are close, their evolutionary behaviors display rich patterns. It has potential use in analyzing physiological signals, detecting early warning signals, and so on. As an emphasis, the our core contribution is that by means of the proposed method one can estimate precisely shannon entropy from limited records. PMID:25549356

  19. Short Acceleration Times from Superdiffusive Shock Acceleration in the Heliosphere

    NASA Astrophysics Data System (ADS)

    Perri, S.; Zimbardo, G.

    2015-12-01

    The analysis of time profiles of particles accelerated at interplanetary shocks allows particle transport properties to be inferred. The frequently observed power-law decay upstream, indeed, implies a superdiffusive particle transport when the level of magnetic field variance does not change as the time interval from the shock front increases. In this context, a superdiffusive shock acceleration (SSA) theory has been developed, allowing us to make predictions of the acceleration times. In this work we estimate for a number of interplanetary shocks, including the solar wind termination shock, the acceleration times for energetic protons in the framework of SSA and we compare the results with the acceleration times predicted by standard diffusive shock acceleration. The acceleration times due to SSA are found to be much shorter than in the classical model, and also shorter than the interplanetary shock lifetimes. This decrease of the acceleration times is due to the scale-free nature of the particle displacements in the framework of superdiffusion. Indeed, very long displacements are possible, increasing the probability for particles far from the front of the shock to return, and short displacements have a high probability of occurrence, increasing the chances for particles close to the front to cross the shock many times.

  20. Signal estimation from modified short-time Fourier transform

    NASA Astrophysics Data System (ADS)

    Griffin, D. W.; Lim, J. S.

    1984-04-01

    An algorithm to estimate a signal from its modified short-time Fourier transform (STFT) is presented. This algorithm is computationally simple and is obtained by minimizing the mean squared error between the STFT of the estimated signal and the modified STFT. Using this algorithm, an iterative algorithm to estimate a signal from its modified STFT magnitude is also developed. The iterative algorithm is shown to decrease, in each iteration, the mean squared error between the STFT magnitude of the estimated signal and the modified STFT magnitude. The major computation involved in the iterative algorithm is the discrete Fourier transform computation, and the algorithm appears to be real-time implementable with current hardware technology. The algorithm developed has been applied to the time-scale modification of speech. The resulting system generates very high-quality speech, and appears to be better in performance than any existing method.

  1. Stability of short-contact-time liquefaction products

    SciTech Connect

    Wham, R.M.; Wortman, J.E.; Dinsmore, T.V.; Rodgers, B.R.

    1982-01-01

    Short-contact-time coal-liquefaction material produced in 19-cc tubing bomb reactors from Kentucky No. 9 coal and Wilsonville recycle solvent has been analyzed for total conversion to pyridine solubles and preasphaltenes, asphaltenes, oils, and residue composition. Pyridine solubility correlated well with a reaction-severity parameter that accounts for residence time and the total thermal history of the product. However, preliminary fractionation data do not show clear monotonic trends when examined in terms of this parameter. Magnetically beneficiated samples of Kentucky No. 9 coal are being evaluated for conversion under short-contact-time liquefaction conditions. Preliminary results show the conversion of the parent coal to be 79% on a MAF basis. The fraction produced at the low end of the magnetic susceptibility spectrum exhibits an 89% MAF conversion. Additional runs will further examine liquefaction behavior in other portions of the spectrum. The standard-run conditions are 5 minutes at 425/sup 0/C for 3 minutes allowed for heat-up.

  2. Experimental Study of Short-Time Brownian Motion

    NASA Astrophysics Data System (ADS)

    Mo, Jianyong; Simha, Akarsh; Riegler, David; Raizen, Mark

    2015-03-01

    We report our progress on the study of short-time Brownian motion of optically-trapped microspheres. In earlier work, we observed the instantaneous velocity of microspheres in gas and in liquid, verifying a prediction by Albert Einstein from 1907. We now report a more accurate test of the energy equipartition theorem for a particle in liquid. We also observe boundary effects on Brownian motion in liquid by setting a wall near the trapped particle, which changes the dynamics of the motion. We find that the velocity autocorrelation of the particle decreases faster as the particle gets closer to the wall.

  3. Target time smearing with short transmissions and multipath propagation.

    PubMed

    Harrison, Chris H

    2011-09-01

    In active sonar the target echo level is often estimated with a propagation model that adds all multipath arrivals. If the (post-correlator) transmitted pulse is short compared to the multipath time spread then there is effectively an extra loss (which may be substantial) since only a few of the paths contribute to the target echo at any one instant. This well known "time-smearing" loss is treated in a self-consistent manner with previous calculations of reverberation [Harrison, J. Acoust. Soc. Am. 114, 2744-2756 (2003)] to estimate the target response and the signal-to-reverberation-ratio. Again isovelocity water, Lambert's law, and reflection loss proportional to angle are assumed. In this important short pulse regime the target response becomes independent of boundary reflection properties but proportional to transmitted pulse length. Thus the signal-to-reverberation-ratio becomes independent of pulse length. The effect on signal-to-ambient-noise is also investigated and the resulting formulas presented in a table. PMID:21895070

  4. Short time die attach characterisation of semiconductor devices

    E-print Network

    P. Szabo; M. Rencz

    2008-01-07

    Thermal qualification of the die attach of semiconductor devices is a very important element in the device characterization as the temperature of the chip is strongly affected by the quality of the die attach. Voids or delaminations in this layer may cause higher temperature elevation and thus damage or shorter lifetime. Thermal test of each device in the manufacturing process would be the best solution for eliminating the devices with wrong die attach layer. In this paper we will present the short time thermal transient measurement method and the structure function evaluation through simulations and measurements for die attach characterization. We will also present a method for eliminating the very time consuming calibration process. Using the proposed methods even the in-line testing of LEDs can be accomplished.

  5. Time Window from Visual Images to Visual Short-Term Memory

    E-print Network

    Jiang, Yuhong

    Time Window from Visual Images to Visual Short-Term Memory: Consolidation or Integration? Yuhong are briefly presented, separated by a short interval of time, visual short-term memory of the first array by subsequent images that also need to be memorized. Key words: visual short-term memory, visual integration

  6. Short- and Long- Time Transport Structures in a Three Dimensional Time Dependent Flow

    E-print Network

    Rodolphe Chabreyrie; Stefan G. Llewellyn Smith

    2014-05-08

    Lagrangian transport structures for three-dimensional and time-dependent fluid flows are of great interest in numerous applications, particularly for geophysical or oceanic flows. In such flows, chaotic transport and mixing can play important environmental and ecological roles, for examples in pollution spills or plankton migration. In such flows, where simulations or observations are typically available only over a short time, understanding the difference between short-time and long-time transport structures is critical. In this paper, we use a set of classical (i.e. Poincar\\'e section, Lyapunov exponent) and alternative (i.e. finite time Lyapunov exponent, Lagrangian coherent structures) tools from dynamical systems theory that analyze chaotic transport both qualitatively and quantitatively. With this set of tools we are able to reveal, identify and highlight differences between short- and long-time transport structures inside a flow composed of a primary horizontal contra-rotating vortex chain, small lateral oscillations and a weak Ekman pumping. The difference is mainly the existence of regular or extremely slowly developing chaotic regions that are only present at short time.

  7. Short-term Time Step Convergence in a Climate Model

    SciTech Connect

    Wan, Hui; Rasch, Philip J.; Taylor, Mark; Jablonowski, Christiane

    2015-02-11

    A testing procedure is designed to assess the convergence property of a global climate model with respect to time step size, based on evaluation of the root-mean-square temperature difference at the end of very short (1 h) simulations with time step sizes ranging from 1 s to 1800 s. A set of validation tests conducted without sub-grid scale parameterizations confirmed that the method was able to correctly assess the convergence rate of the dynamical core under various configurations. The testing procedure was then applied to the full model, and revealed a slow convergence of order 0.4 in contrast to the expected first-order convergence. Sensitivity experiments showed without ambiguity that the time stepping errors in the model were dominated by those from the stratiform cloud parameterizations, in particular the cloud microphysics. This provides a clear guidance for future work on the design of more accurate numerical methods for time stepping and process coupling in the model.

  8. Short-term time step convergence in a climate model

    DOE PAGESBeta

    Wan, Hui; Rasch, Philip J.; Taylor, Mark; Jablonowski, Christiane

    2015-02-11

    A testing procedure is designed to assess the convergence property of a global climate model with respect to time step size, based on evaluation of the root-mean-square temperature difference at the end of very short (1 h) simulations with time step sizes ranging from 1 s to 1800 s. A set of validation tests conducted without sub-grid scale parameterizations confirmed that the method was able to correctly assess the convergence rate of the dynamical core under various configurations. The testing procedure was then applied to the full model, and revealed a slow convergence of order 0.4 in contrast to themore »expected first-order convergence. Sensitivity experiments showed without ambiguity that the time stepping errors in the model were dominated by those from the stratiform cloud parameterizations, in particular the cloud microphysics. This provides a clear guidance for future work on the design of more accurate numerical methods for time stepping and process coupling in the model.« less

  9. Short-term Time Step Convergence in a Climate Model

    DOE PAGESBeta

    Wan, Hui; Rasch, Philip J.; Taylor, Mark; Jablonowski, Christiane

    2015-02-11

    A testing procedure is designed to assess the convergence property of a global climate model with respect to time step size, based on evaluation of the root-mean-square temperature difference at the end of very short (1 h) simulations with time step sizes ranging from 1 s to 1800 s. A set of validation tests conducted without sub-grid scale parameterizations confirmed that the method was able to correctly assess the convergence rate of the dynamical core under various configurations. The testing procedure was then applied to the full model, and revealed a slow convergence of order 0.4 in contrast to themore »expected first-order convergence. Sensitivity experiments showed without ambiguity that the time stepping errors in the model were dominated by those from the stratiform cloud parameterizations, in particular the cloud microphysics. This provides a clear guidance for future work on the design of more accurate numerical methods for time stepping and process coupling in the model.« less

  10. Predator-prey interactions, resource depression and patch revisitation

    USGS Publications Warehouse

    Erwin, R.M.

    1989-01-01

    Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short 'recovery' times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.

  11. An Incremental Algorithm for Signal Reconstruction from Short-Time Fourier Transform Magnitude

    E-print Network

    Ezzat, Tony

    An Incremental Algorithm for Signal Reconstruction from Short-Time Fourier Transform Magnitude Jake@mit.edu Abstract We present an algorithm for reconstructing a time-domain signal from the magnitude of a short-domain signal from only the magnitude of the short-time Fourier transform (STFT) is a common prob- lem in speech

  12. VARIABILITY OF SOLAR RADIATION DATA OVER SHORT TIME INTERVALS Frank Vignola

    E-print Network

    Oregon, University of

    to evaluate satellite and cloud cover models, it is useful to understand the short-term variability of solar the short term variability of solar radiation. Two aspects of the variability of solar radiation over shortVARIABILITY OF SOLAR RADIATION DATA OVER SHORT TIME INTERVALS Frank Vignola Department of Physics

  13. Variations in solar Lyman alpha irradiance on short time scales

    NASA Technical Reports Server (NTRS)

    Pap, J. M.

    1992-01-01

    Variations in solar UV irradiance at Lyman alpha are studied on short time scales (from days to months) after removing the long-term changes over the solar cycle. The SME/Lyman alpha irradiance is estimated from various solar indices using linear regression analysis. In order to study the nonlinear effects, Lyman alpha irradiance is modeled with a 5th-degree polynomial as well. It is shown that the full-disk equivalent width of the He line at 1083 nm, which is used as a proxy for the plages and active network, can best reproduce the changes observed in Lyman alpha. Approximately 72 percent of the solar-activity-related changes in Lyman alpha irradiance arise from plages and the network. The network contribution is estimated by the correlation analysis to be about 19 percent. It is shown that significant variability remains in Lyman alpha irradiance, with periods around 300, 27, and 13.5d, which is not explained by the solar activity indices. It is shown that the nonlinear effects cannot account for a significant part of the unexplained variation in Lyman alpha irradiance. Therefore, additional events (e.g., large-scale motions and/or a systematic difference in the area and intensity of the plages and network observed in the lines of Ca-K, He 1083, and Lyman alpha) may explain the discrepancies found between the observed and estimated irradiance values.

  14. A Method of Human Short Hair Modeling and Real Time Animation Volume Interactions

    E-print Network

    Huang, Zhiyong

    A Method of Human Short Hair Modeling and Real Time Animation Yang Guang Volume Interactions 5@comp.nus.edu.sg Abstract This paper describes a method of human short hair mod- eling and real time animation. A method is proposed to model the short hair. First, a hair style model is derived from a scalp model interactively

  15. WHO, RECIST, and immune-related response criteria: is it time to revisit pembrolizumab results?

    PubMed Central

    Ades, Felipe; Yamaguchi, Nise

    2015-01-01

    In recent years, with the rise of immunotherapeutic agents for cancer treatment, we have observed a paradigm shift in oncology drug development. One common problem accompanying such paradigm shifts is how to build research strategies to fit the mechanism of action of the newer compounds. Developing immunotherapy in oncology requires us to address the unique characteristics of immunotherapeutic agents and to provide adequate tools for their evaluation, including the adjustment of clinical trial endpoints. Immunotherapy creates patterns of response different from those of chemotherapy, and thus they are not captured by the traditional World Health Organisation (WHO) tumour response criteria or the RECIST. Revisiting the results of pembrolizumab in patients with melanoma can help to evaluate the efficacy of the immune-related response criteria (irRC) as the gold standard for evaluating the clinical response of immunologic agents in oncology. PMID:26715941

  16. Short-Distance Space-Time Structure and Black Holes in String Theory A Short Review of the Present Status

    E-print Network

    Li, Maozhen; Li, Miao; Yoneya, Tamiaki

    1998-01-01

    We briefly review the present status of string theory from the viewpoint of its implications on the short-distance space-time structure and black hole physics. Special emphases are given on two closely related issues in recent developments towards nonperturbative string theory, namely, the role of the space-time uncertainty relation as a qualitative but universal characterization of the short-distance structure of string theory and the microscopic formulation of black-hole entropies. We will also suggest that the space-time uncertainty relation can be an underlying principle for the holographic property of M theory, by showing that the space-time uncertainty relation naturally explains the UV/IR relation used in a recent derivation of the holographic bound for D3 brane by Susskind and Witten.

  17. Speech enhancement using a minimum mean-square error short-time spectral modulation magnitude estimator

    E-print Network

    Speech enhancement using a minimum mean-square error short-time spectral modulation magnitude In this paper we investigate the enhancement of speech by applying MMSE short-time spectral magnitude estimation values that maximise the subjective quality of stimuli enhanced using the MMSE modulation magnitude

  18. Single channel speech enhancement using MMSE estimation of short-time modulation magnitude spectrum

    E-print Network

    Single channel speech enhancement using MMSE estimation of short-time modulation magnitude spectrum magnitude estimation in the modulation domain. For this purpose, the traditional analysis- modification for additive noise distortion by applying the MMSE short-time spectral magnitude estimation algorithm

  19. Further intelligibility results from human listening tests using the short-time phase spectrum

    E-print Network

    Further intelligibility results from human listening tests using the short-time phase spectrum is generally ignored in these systems. Results from our recent human listening tests indicate that the short-time phase spectrum can significantly contribute to speech intelligibility over small window durations (i

  20. An Optimal Mitigation Strategy Against the Asteroid Impact Threat with Short Warning Time

    NASA Technical Reports Server (NTRS)

    Wie, Bong; Barbee, Brent; Pitz, Alan; Kaplinger, Brian; Hawkins, Matt; Winkler, Tim; Premaratne, Pavithra; Vardaxis, George; Lyzhoft, Joshua; Zimmerman, Ben

    2015-01-01

    To develop an innovative yet practically implementable mitigation technique for the most probable impact threat of an asteroid or comet with short warning time (i.e., when we don't have sufficient warning times for a deflection mission).

  1. Effect of heating strategies on whey protein denaturation-Revisited by liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    Akkerman, M; Rauh, V M; Christensen, M; Johansen, L B; Hammershøj, M; Larsen, L B

    2016-01-01

    Previous standards in the area of effect of heat treatment processes on milk protein denaturation were based primarily on laboratory-scale analysis and determination of denaturation degrees by, for example, electrophoresis. In this study, whey protein denaturation was revisited by pilot-scale heating strategies and liquid chromatography quadrupole time-of-flight mass spectrometer (LC/MC Q-TOF) analysis. Skim milk was heat treated by the use of 3 heating strategies, namely plate heat exchanger (PHE), tubular heat exchanger (THE), and direct steam injection (DSI), under various heating temperatures (T) and holding times. The effect of heating strategy on the degree of denaturation of ?-lactoglobulin and ?-lactalbumin was determined using LC/MC Q-TOF of pH 4.5-soluble whey proteins. Furthermore, effect of heating strategy on the rennet-induced coagulation properties was studied by oscillatory rheometry. In addition, rennet-induced coagulation of heat-treated micellar casein concentrate subjected to PHE was studied. For skim milk, the whey protein denaturation increased significantly as T and holding time increased, regardless of heating method. High denaturation degrees were obtained for T >100°C using PHE and THE, whereas DSI resulted in significantly lower denaturation degrees, compared with PHE and THE. Rennet coagulation properties were impaired by increased T and holding time regardless of heating method, although DSI resulted in less impairment compared with PHE and THE. No significant difference was found between THE and PHE for effect on rennet coagulation time, whereas the curd firming rate was significantly larger for THE compared with PHE. Micellar casein concentrate possessed improved rennet coagulation properties compared with skim milk receiving equal heat treatment. PMID:26506552

  2. Highly optimized fourth-order short-time approximation for pathintegrals

    SciTech Connect

    Predescu, Cristian

    2006-10-01

    We derive a fourth-order short-time approximation for use in imaginary-time path-integral simulations. The short-time approximation converges for all continuous and bounded from below potentials, attains quartic order of convergence for sufficiently smooth potentials, and utilizes statistically independent random variables for its construction. These properties recommend the approximation as a natural replacement of the trapezoidal Trotter-Suzuki approximation for physical systems with continuous distributions.

  3. Deducing acidification rates based on short-term time series

    PubMed Central

    Lui, Hon-Kit; Arthur Chen, Chen-Tung

    2015-01-01

    We show that, statistically, the simple linear regression (SLR)-determined rate of temporal change in seawater pH (?pH), the so-called acidification rate, can be expressed as a linear combination of a constant (the estimated rate of temporal change in pH) and SLR-determined rates of temporal changes in other variables (deviation largely due to various sampling distributions), despite complications due to different observation durations and temporal sampling distributions. Observations show that five time series data sets worldwide, with observation times from 9 to 23 years, have yielded ?pH values that vary from 1.61?×?10?3 to ?2.5?×?10?3?pH unit yr?1. After correcting for the deviation, these data now all yield an acidification rate similar to what is expected under the air-sea CO2 equilibrium (?1.6?×?10?3?~??1.8?×?10?3?pH unit yr?1). Although long-term time series stations may have evenly distributed datasets, shorter time series may suffer large errors which are correctable by this method. PMID:26143749

  4. Short communication Real-time estimation of lead-acid battery parameters: A dynamic

    E-print Network

    Ray, Asok

    Short communication Real-time estimation of lead-acid battery parameters: A dynamic data of State of charge (SOC) and State of health (SOH) in lead-acid batteries. Algorithm development based Lead-acid battery Symbolic dynamic filtering k-NN regression a b s t r a c t This short paper presents

  5. A short introduction to viscosity solutions and the large time behavior of solutions of

    E-print Network

    Matsuzaki, Katsuhiko

    A short introduction to viscosity solutions and the large time behavior of solutions of Hamilton to the theory of viscosity solutions of first- order partial differential equations and a review on the optimal introduction to viscosity solutions of first-order partial differential equations (PDE for short) and to review

  6. Short-time dynamics in dispersions with competing short-range attraction and long-range repulsion.

    PubMed

    Riest, Jonas; Nägele, Gerhard

    2015-12-01

    Dynamic clustering of globular Brownian particles in dispersions exhibiting competing short-range attraction and long-range repulsion (SALR) such as low-salinity protein solutions has gained a lot of interest over the past few years. While the structure of the various cluster phases has been intensely explored, little is known about the dynamics of SALR systems. We present the first systematic theoretical study of short-time diffusion and rheological transport properties of two-Yukawa potential SALR systems in the single-particle dominated dispersed-fluid phase, using semi-analytic methods where the salient hydrodynamic interactions are accounted for. We show that the dynamics has unusual features compared to reference systems with pure repulsion or attraction. Results are discussed for the hydrodynamic function characterizing short-time diffusion that reveals an intermediate-range-order (cluster) peak, self-diffusion and sedimentation coefficients, and high-frequency viscosity. As important applications, we discuss the applicability of two generalized Stokes-Einstein relations, and assess the wavenumber range required for the determination of self-diffusion in a dynamic scattering experiment. PMID:26426932

  7. Short residence time coal liquefaction process including catalytic hydrogenation

    DOEpatents

    Anderson, Raymond P. (Overland Park, KS); Schmalzer, David K. (Englewood, CO); Wright, Charles H. (Overland Park, KS)

    1982-05-18

    Normally solid dissolved coal product and a distillate liquid product are produced by continuously passing a feed slurry comprising raw feed coal and a recycle solvent oil and/or slurry together with hydrogen to a preheating-reaction zone (26, alone, or 26 together with 42), the hydrogen pressure in the preheating-reaction zone being at least 1500 psig (105 kg/cm.sup.2), reacting the slurry in the preheating-reaction zone (26, or 26 with 42) at a temperature in the range of between about 455.degree. and about 500.degree. C. to dissolve the coal to form normally liquid coal and normally solid dissolved coal. A total slurry residence time is maintained in the reaction zone ranging from a finite value from about 0 to about 0.2 hour, and reaction effluent is continuously and directly contacted with a quenching fluid (40, 68) to substantially immediately reduce the temperature of the reaction effluent to below 425.degree. C. to substantially inhibit polymerization so that the yield of insoluble organic matter comprises less than 9 weight percent of said feed coal on a moisture-free basis. The reaction is performed under conditions of temperature, hydrogen pressure and residence time such that the quantity of distillate liquid boiling within the range C.sub.5 -454.degree. C. is an amount at least equal to that obtainable by performing the process under the same condition except for a longer total slurry residence time, e.g., 0.3 hour. Solvent boiling range liquid is separated from the reaction effluent (83) and recycled as process solvent (16). The amount of solvent boiling range liquid is sufficient to provide at least 80 weight percent of that required to maintain the process in overall solvent balance.

  8. Short residence time coal liquefaction process including catalytic hydrogenation

    DOEpatents

    Anderson, R.P.; Schmalzer, D.K.; Wright, C.H.

    1982-05-18

    Normally solid dissolved coal product and a distillate liquid product are produced by continuously passing a feed slurry comprising raw feed coal and a recycle solvent oil and/or slurry together with hydrogen to a preheating-reaction zone, the hydrogen pressure in the preheating-reaction zone being at least 1,500 psig (105 kg/cm[sup 2]), reacting the slurry in the preheating-reaction zone at a temperature in the range of between about 455 and about 500 C to dissolve the coal to form normally liquid coal and normally solid dissolved coal. A total slurry residence time is maintained in the reaction zone ranging from a finite value from about 0 to about 0.2 hour, and reaction effluent is continuously and directly contacted with a quenching fluid to substantially immediately reduce the temperature of the reaction effluent to below 425 C to substantially inhibit polymerization so that the yield of insoluble organic matter comprises less than 9 weight percent of said feed coal on a moisture-free basis. The reaction is performed under conditions of temperature, hydrogen pressure and residence time such that the quantity of distillate liquid boiling within the range C[sub 5]-454 C is an amount at least equal to that obtainable by performing the process under the same condition except for a longer total slurry residence time, e.g., 0.3 hour. Solvent boiling range liquid is separated from the reaction effluent and recycled as process solvent. The amount of solvent boiling range liquid is sufficient to provide at least 80 weight percent of that required to maintain the process in overall solvent balance. 6 figs.

  9. Short-time forecasting of the system magnetosheath -magnetosphere

    NASA Astrophysics Data System (ADS)

    Dobreva, Polya; Iliev, Hristo; Grigorov, Krum; Koitchev, Detelin; Keremidarska, Valentina; Kartalev, Monio

    We report on the efforts to optimize the performance of a new magnetosphere-magnetosheath model in order to achieve at least 30 minutes forecasting advance of the near-Earth space. The utilized model, developed at the Institute of Mechanics, Bulgarian Academy of Sciences, consists of two models, describing self-consistently the magnetosheath-magnetosphere system. The 3D magnetosheath modul receives the flow distribution at the magnetosheath region (in gasdynamic approach). The magnetosphere model is a modification of the Tsyganenko magnetic field model with numerically calculated shielding field and boundary. The locations and shapes of the bow shock and magnetopause are also described as a part of the solution. The 3D form of the magnetopause (generally non-axially-symmetric), including the cusp indentation, influences essentially the flow. Input data for the whole model are density, temperature, flow velocity and interplanetary magnetic field (IMF). A complementary part of the system is a set of algorithms and programs, making use of the available in Internet near real time solar wind monitoring in L1 (currently performed by ACE). In order to modernize and extend the existing simulation software, several performance optimization techniques were applied to the FORTRAN source code. Also parts of the code are being incrementally parallelized using OpenMP directives. The simulations run on several multicore x86-64 machines under 64-bit Linux OS. The traveling time of the solar wind from L1 to the Earth is enough for running the magnetosheath-magnetosphere problem. Numerical experiments, performed on different configuration of the computer platform are discussed.

  10. Time-dependent Bragg diffraction and short-pulse reflection by one-dimensional photonic crystals

    E-print Network

    André, Jean-michel

    2015-01-01

    The time-dependence of the Bragg diffraction by one-dimensional photonic crystals and its influence on the short pulse reflection are studied in the framework of the coupled- wave theory. The indicial response of the photonic crystal is calculated and it appears that it presents a time-delay effect with a transient time conditioned by the extinction length. A numerical simulation is presented for a Bragg mirror in the x-ray domain and a pulse envelope modelled by a sine-squared shape. The potential consequences of the time-delay effect in time-dependent optics of short-pulses are emphasized.

  11. High voltage electrical amplifier having a short rise time

    DOEpatents

    Christie, David J. (Pleasanton, CA); Dallum, Gregory E. (Livermore, CA)

    1991-01-01

    A circuit, comprising an amplifier and a transformer is disclosed that produces a high power pulse having a fast response time, and that responds to a digital control signal applied through a digital-to-analog converter. The present invention is suitable for driving a component such as an electro-optic modulator with a voltage in the kilovolt range. The circuit is stable at high frequencies and during pulse transients, and its impedance matching circuit matches the load impedance with the output impedance. The preferred embodiment comprises an input stage compatible with high-speed semiconductor components for amplifying the voltage of the input control signal, a buffer for isolating the input stage from the output stage; and a plurality of current amplifiers connected to the buffer. Each current amplifier is connected to a field effect transistor (FET), which switches a high voltage power supply to a transformer which then provides an output terminal for driving a load. The transformer comprises a plurality of transmission lines connected to the FETs and the load. The transformer changes the impedance and voltage of the output. The preferred embodiment also comprises a low voltage power supply for biasing the FETs at or near an operational voltage.

  12. Short-term Direct Travel time Prediction for Freeway Deepak Kumar Jayabalan

    E-print Network

    Gautam, Natarajan

    Short-term Direct Travel time Prediction for Freeway Segments By Deepak Kumar Jayabalan Market-term travel time prediction problem on a link level basis (section of freeway between adjacent traffic sensors variable (actual vehicle travel time) on the explanatory variables (detector measurements of speed, flow

  13. Healthy Work Revisited: Do Changes in Time Strain Predict Well-Being?

    PubMed Central

    Moen, Phyllis; Kelly, Erin L.; Lam, Jack

    2013-01-01

    Building on Karasek and Theorell (R. Karasek & T. Theorell, 1990, Healthy work: Stress, productivity, and the reconstruction of working life, New York, NY: Basic Books), we theorized and tested the relationship between time strain (work-time demands and control) and seven self-reported health outcomes. We drew on survey data from 550 employees fielded before and 6 months after the implementation of an organizational intervention, the Results Only Work Environment (ROWE) in a white-collar organization. Cross-sectional (Wave 1) models showed psychological time demands and time control measures were related to health outcomes in expected directions. The ROWE intervention did not predict changes in psychological time demands by Wave 2, but did predict increased time control (a sense of time adequacy and schedule control). Statistical models revealed increases in psychological time demands and time adequacy predicted changes in positive (energy, mastery, psychological well-being, self-assessed health) and negative (emotional exhaustion, somatic symptoms, psychological distress) outcomes in expected directions, net of job and home demands and covariates. This study demonstrates the value of including time strain in investigations of the health effects of job conditions. Results encourage longitudinal models of change in psychological time demands as well as time control, along with the development and testing of interventions aimed at reducing time strain in different populations of workers. PMID:23506547

  14. Method to modify random matrix theory using short-time behavior in chaotic systems

    NASA Astrophysics Data System (ADS)

    Smith, A. Matthew; Kaplan, Lev

    2009-09-01

    We discuss a modification to random matrix theory (RMT) eigenstate statistics that systematically takes into account the nonuniversal short-time behavior of chaotic systems. The method avoids diagonalization of the Hamiltonian, instead requiring only knowledge of short-time dynamics for a chaotic system or ensemble of similar systems. Standard RMT and semiclassical predictions are recovered in the limits of zero Ehrenfest time and infinite Heisenberg time, respectively. As examples, we discuss wave-function autocorrelations and cross correlations and show how the approach leads to a significant improvement in the accuracy for simple chaotic systems where comparison can be made with brute-force diagonalization.

  15. A Method to Modify RMT using Short-Time Behavior in Chaotic Systems

    E-print Network

    A. Matthew Smith; Lev Kaplan

    2009-07-29

    We discuss a modification to Random Matrix Theory eigenstate statistics, that systematically takes into account the non-universal short-time behavior of chaotic systems. The method avoids diagonalization of the Hamiltonian, instead requiring only a knowledge of short-time dynamics for a chaotic system or ensemble of similar systems. Standard Random Matrix Theory and semiclassical predictions are recovered in the limits of zero Ehrenfest time and infinite Heisenberg time, respectively. As examples, we discuss wave function autocorrelations and cross-correlations, and show how the approach leads to a significant improvement in accuracy for simple chaotic systems where comparison can be made with brute-force diagonalization.

  16. Revisiting the Time Trade-Off Hypothesis: Work, Organized Activities, and Academics During College.

    PubMed

    Greene, Kaylin M; Maggs, Jennifer L

    2015-08-01

    How adolescents spend their time has long-term implications for their educational, health, and labor market outcomes, yet surprisingly little research has explored the time use of students across days and semesters. The current study used longitudinal daily diary data from a sample of college students attending a large public university in the Northeastern US (n = 726, M age = 18.4) that was followed for 14 days within each of seven semesters (for up to 98 diary days per student). The study had two primary aims. The first aim was to explore demographic correlates of employment time, organized activity time, and academic time. The second aim was to provide a rigorous test of the time trade-off hypothesis, which suggests that students will spend less time on academics when they spend more time on employment and extracurricular activities. The results demonstrated that time use varied by gender, parental education, and race/ethnicity. Furthermore, the results from multi-level models provided some support for the time trade-off hypothesis, although associations varied by the activity type and whether the day was a weekend. More time spent on employment was linked to less time spent on academics across days and semesters whereas organized activities were associated with less time on academics at the daily level only. The negative associations between employment and academics were most pronounced on weekdays. These results suggest that students may balance certain activities across days, whereas other activities may be in competition over longer time frames (i.e., semesters). PMID:25381597

  17. Integrating Random Matrix Theory Predictions with Short-Time Dynamical Effects in Chaotic Systems

    E-print Network

    A. Matthew Smith; Lev Kaplan

    2010-06-29

    We discuss a modification to Random Matrix Theory eigenstate statistics, that systematically takes into account the non-universal short-time behavior of chaotic systems. The method avoids diagonalization of the Hamiltonian, instead requiring only a knowledge of short-time dynamics for a chaotic system or ensemble of similar systems. Standard Random Matrix Theory and semiclassical predictions are recovered in the limits of zero Ehrenfest time and infinite Heisenberg time, respectively. As examples, we discuss wave function autocorrelations and cross-correlations, and show that significant improvement in accuracy is obtained for simple chaotic systems where comparison can be made with brute-force diagonalization. The accuracy of the method persists even when the short-time dynamics of the system or ensemble is known only in a classical approximation. Further improvement in the rate of convergence is obtained when the method is combined with the correlation function bootstrapping approach introduced previously.

  18. Real-time mobile customer short message system design and implementation

    NASA Astrophysics Data System (ADS)

    Han, Qirui; Sun, Fang

    To expand the current mobile phone short message service, and to make the contact between schools, teachers, parents and feedback of the modern school office system more timely and conveniently, designed and developed the Short Message System based on the Linux platform. The state-of-the-art principles and designed proposals in the Short Message System based on the Linux platform are introduced. Finally we propose an optimized secure access authentication method. At present, many schools,vbusinesses and research institutions ratify the promotion and application the messaging system gradually, which has shown benign market prospects.

  19. Active mode-locking of mid-infrared quantum cascade lasers with short gain recovery time.

    PubMed

    Wang, Yongrui; Belyanin, Alexey

    2015-02-23

    We investigate the dynamics of actively modulated mid-infrared quantum cascade lasers (QCLs) using space- and time-domain simulations of coupled density matrix and Maxwell equations with resonant tunneling current taken into account. We show that it is possible to achieve active mode locking and stable generation of picosecond pulses in high performance QCLs with a vertical laser transition and a short gain recovery time by bias modulation of a short section of a monolithic Fabry-Perot cavity. In fact, active mode locking in QCLs with a short gain recovery time turns out to be more robust to the variation of parameters as compared to previously studied lasers with a long gain recovery time. We investigate the effects of spatial hole burning and phase locking on the laser output. PMID:25836455

  20. Short-time evolution of Lagrangian velocity gradient correlations in isotropic turbulence

    E-print Network

    Fang, Le; Jin, G D

    2015-01-01

    We show by direct numerical simulation (DNS) that the Lagrangian cross correlation of velocity gradients in homogeneous isotropic turbulence increases at short times, whereas its auto-correlation decreases. Kinematic considerations allow to show that two invariants of the turbulent velocity field determine the short-time velocity gradient correlations. In order to get a more intuitive understanding of the dynamics for longer times, heuristic models are proposed involving the combined action of local shear and rotation. These models quantitatively reproduce the effects and disentangle the different physical mechanisms leading to the observations in the DNS.

  1. Viruses as groundwater tracers: using ecohydrology to characterize short travel times in aquifers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Viruses are attractive tracers of short (<3 yr) travel times in aquifers because they have unique genetic signatures, are detectable in trace quantities, and are mobile and stable in groundwater. Virus “snaphots” result from infection and disappearance over time as a community develops resistance. T...

  2. Short Term Chaotic Time Series Prediction using Symmetric LS-SVM Regression

    E-print Network

    Short Term Chaotic Time Series Prediction using Symmetric LS-SVM Regression Marcelo Espinoza, Johan predictions for chaotic time series are generated using Least-Squares Support Vector Ma- chines (LS-SVM) regression. We show that LS-SVM with symmetry constraints can produce accurate pre- dictions. Not only

  3. Short time Fourier analysis of the electromyogram - Fast movements and constant contraction

    NASA Technical Reports Server (NTRS)

    Hannaford, Blake; Lehman, Steven

    1986-01-01

    Short-time Fourier analysis was applied to surface electromyograms (EMG) recorded during rapid movements, and during isometric contractions at constant forces. A portion of the data to be transformed by multiplying the signal by a Hamming window was selected, and then the discrete Fourier transform was computed. Shifting the window along the data record, a new spectrum was computed each 10 ms. The transformed data were displayed in spectograms or 'voiceprints'. This short-time technique made it possible to see time-dependencies in the EMG that are normally averaged in the Fourier analysis of these signals. Spectra of EMGs during isometric contractions at constant force vary in the short (10-20 ms) term. Short-time spectra from EMGs recorded during rapid movements were much less variable. The windowing technique picked out the typical 'three-burst pattern' in EMG's from both wrist and head movements. Spectra during the bursts were more consistent than those during isometric contractions. Furthermore, there was a consistent shift in spectral statistics in the course of the three bursts. Both the center frequency and the variance of the spectral energy distribution grew from the first burst to the second burst in the same muscle. The analogy between EMGs and speech signals is extended to argue for future applicability of short-time spectral analysis of EMG.

  4. Temporal moments revisited: Why there is no better way for physically based model reduction in time

    NASA Astrophysics Data System (ADS)

    Leube, P. C.; Nowak, W.; Schneider, G.

    2012-11-01

    Many hydro(geo)logical problems are highly complex in space and time, coupled with scale issues, variability, and uncertainty. Especially time-dependent models often consume enormous computational resources, but model reduction techniques can alleviate this problem. Temporal moments (TM) offer an approach to reduce the time demands of transient hydro(geo)logical simulations. TM reduce transient governing equations to steady state and directly simulate the temporal characteristics of the system, if the equations are linear and coefficients are time independent. This is achieved by an integral transform, projecting the dynamic system response onto monomials in time. In comparison to classical approaches of model reduction that involve orthogonal base functions, however, the monomials for TM are nonorthogonal, which might impair the quality and efficiency of model reduction. Thus, we raise the question of whether there are more suitable temporal base functions than the monomials that lead to TM. In this work, we will derive theoretically that there is only a limited class of temporal base functions that can reduce hydro(geo)logical models. By comparing those to TM we conclude that, in terms of gained efficiency versus maintained accuracy, TM are the best possible choice. While our theoretical results hold for all systems of linear partial or ordinary differential equations (PDEs, ODEs) with any order of space and time derivatives, we illustrate our study with an example of pumping tests in a confined aquifer. For that case, we demonstrate that two (four) TM are sufficient to represent more than 80% (90%) of the dynamic behavior, and that the information content strictly increases with increasing TM order.

  5. Detecting causality from nonlinear dynamics with short-term time series.

    PubMed

    Ma, Huanfei; Aihara, Kazuyuki; Chen, Luonan

    2014-01-01

    Quantifying causality between variables from observed time series data is of great importance in various disciplines but also a challenging task, especially when the observed data are short. Unlike the conventional methods, we find it possible to detect causality only with very short time series data, based on embedding theory of an attractor for nonlinear dynamics. Specifically, we first show that measuring the smoothness of a cross map between two observed variables can be used to detect a causal relation. Then, we provide a very effective algorithm to computationally evaluate the smoothness of the cross map, or "Cross Map Smoothness" (CMS), and thus to infer the causality, which can achieve high accuracy even with very short time series data. Analysis of both mathematical models from various benchmarks and real data from biological systems validates our method. PMID:25501646

  6. Short Contact Time Direct Coal Liquefaction Using a Novel Batch Reactor

    SciTech Connect

    He Huang; Michael T. Klein; William H. Calkins

    1997-01-30

    The primary objective of this research is to optimize the design and operation of the bench scale batch reactor (SCTBR) for studying direct coal liquefaction at short contact times (.01 to 10 minutes or longer). Additional objectives are to study the kinetics of direct coal liquefaction particularly at short reaction times and to investigate the role of organic oxygen components of coal and their reaction pathways during coal liquefaction. Many of those objectives have already been achieved. This quarterly report discusses further kinetic studies of the liquefaction in tetralin of a Montana Lignite, Wyodak-Anderson subbituminous coal, Illinois #6 hv bituminous coal, Pittsburgh #8 hv bituminous coals, and Pocohontas lV bituminous coal at short contact times. All of these coals showed a distinct extraction stage. Further work has also been done to attempt to clarify the role of the liquefaction solvent in the direct liquefaction process.

  7. The physics of heating by time-dependent fields: microwaves and water revisited.

    PubMed

    Huang, Wei; Richert, Ranko

    2008-08-14

    Heating samples by microwave radiation is a particular example of the more general phenomenon where materials absorb energy from an external time-dependent field of an electric, magnetic, or mechanical nature. How this compares with conventional heating is a question of continued interest. Here, we show that the origin of the absorptivity determines whether energy accumulates in the slower configurational degrees of freedom or transfers rapidly to the phonon bath, where only the latter situation is equivalent to conventional heating. Based upon time-resolved measurements of the configurational temperatures, evidence is provided for simple liquids displaying nonthermal behavior if heated by external fields, with molecules being more mobile than expected on the basis of the actual temperature. However, water and related materials are the exception regarding absorptive heating, because energy is transferred to the phonons more rapidly than it is absorbed from the field, and nonthermal effects thus remain absent. PMID:18646805

  8. Dispersion curves from short-time molecular dynamics simulation. 1. Diatomic chain results

    SciTech Connect

    Noid, D.W.; Broocks, B.T.; Gray, S.K.; Marple, S.L.

    1988-06-16

    The multiple signal classification method (MUSIC) for frequency estimation is used to compute the frequency dispersion curves of a diatomic chain from the time-dependent structure factor. In this paper, the authors demonstrate that MUSIC can accurately determine the frequencies from very short time trajectories. MUSIC is also used to show how the frequencies can vary in time, i.e., along a trajectory. The method is ideally suited for analyzing molecular dynamics simulations of large systems.

  9. Revisiting the Stark Broadening by fluctuating electric fields using the Continuous Time Random Walk Theory

    NASA Astrophysics Data System (ADS)

    Capes, H.; Christova, M.; Boland, D.; Catoire, F.; Godbert-Mouret, L.; Koubiti, M.; Mekkaoui, A.; Rosato, J.; Marandet, Y.; Stamm, R.

    2010-10-01

    Stark broadening of atomic lines in plasmas is calculated by modelling the plasma stochastic electric field using the CTRW approach [1,2]. This allows retaining non Markovian terms in the Schrödinger equation averaged over the electric field fluctuations. As an application we consider a special case of a non separable CTRW process, the so called Kangaroo process [3]. An analytic expression for the line profile is presented for arbitrary waiting time distribution functions. A preliminary application to the hydrogen Lyman ? line is discussed.

  10. Circinus X-1 revisited: Fast-timing properties in relation to spectral state

    NASA Technical Reports Server (NTRS)

    Oosterbroek, T.; Van Der Klis, M.; Kuulkers, E.; Van Paradijs, J.; Lewin, W. H. G.

    1995-01-01

    We have studied the X-ray spectral and fast-timing variations of Cir X-1 by performing a homogenous analysis of all EXOSAT ME data on this source using X-ray hardness-intensity diagrams (HIDs), color-color diagrams (CDs), and power spectra. Cir X-1 exhibits a wide range of power spectral shapes and a large variety in X-ray spectral shapes. At different epochs the power spectra variously resemble those of an atoll source, a Z source, a black-hole candidate, or are unlike any of these. At some epochs one-dimensional connected-branch patterns are seen in HID and CD, and at other times more complex structures are found. We interpret the complex behavior of Cir X-1 in terms of a model where accretion rate, orbital phase and epoch are the main determinants of the source behavior, and where the unique properties of the source are due to two special circumstances: (1) the source is the only known atoll source (accreting neutron star with a very low magnetic field) that can reach the Eddington critical accretion rate, and (2) it has a unique, highly eccentric and probably precessing orbit. Property (1) makes Cir X-1 a very important source for our understanding of the similarities in the observable properties of neutron stars and black holes as it allows to separate out black hole signatures from properties that are merely due to the presence of accretion compact with a low magnetic field.

  11. Lakatos Revisited.

    ERIC Educational Resources Information Center

    Court, Deborah

    1999-01-01

    Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social sciences as…

  12. Late-time tails of a self-gravitating massless scalar field, revisited

    E-print Network

    Piotr Bizo?; Tadeusz Chmaj; Andrzej Rostworowski

    2009-08-11

    We discuss the nonlinear origin of the power-law tail in the long-time evolution of a spherically symmetric self-gravitating massless scalar field in even-dimensional spacetimes. Using third-order perturbation method, we derive explicit expressions for the tail (the decay rate and the amplitude) for solutions starting from small initial data and we verify this prediction via numerical integration of the Einstein-scalar field equations in four and six dimensions. Our results show that the coincidence of decay rates of linear and nonlinear tails in four dimensions (which has misguided some tail hunters in the past) is in a sense accidental and does not hold in higher dimensions.

  13. Predicting the Long-Time Dynamic Heterogeneity in a Supercooled Liquid on the Basis of Short-Time Heterogeneities

    SciTech Connect

    Widmer-Cooper, Asaph; Harrowell, Peter

    2006-05-12

    We report that the local Debye-Waller factor in a simulated 2D glass-forming mixture exhibits significant spatial heterogeneities and that these short-time fluctuations provide an excellent predictor of the spatial distribution of the long-time dynamic propensities [Phys. Rev. Lett. 93, 135701 (2004)]. In contrast, the potential energy per particle of the inherent structure does not correlate well with the spatially distributed dynamics.

  14. Short collision time approximation for neutron scattering using discrete frequency distributions

    SciTech Connect

    Ryskamp, J.M.

    1980-01-01

    A completely general form for computing any scattering cross section based on the incoherent approximation without extending f(..omega..) to negative frequencies and without integrating over the complex plane is presented. A simple derivation of the short collision time approximation for discrete frequency distributions is also given. The approximation works well for large incident neutron energies when the duration of a collision is short compared with the natural periods of atomic motion. Single-differential scattering cross sections for light water as computed with the free proton and Nelkin scattering models at 561/sup 0/K, and the short collision time approximation with T/sub eff/ = 1468/sup 0/K, are shown for an incident neutron energy of 1.0 eV. 1 figure. (RWR)

  15. Ageing and Feature Binding in Visual Short-Term Memory: The Role of Presentation Time

    E-print Network

    Rhodes, Stephen

    2012-11-28

    shape and colour in visual short-term memory when given longer to study objects. Therefore, the main aim of the current experiment was to further investigate this intriguing finding by systematically varying the amount of time given to younger and older...

  16. Managing the Editing Function on Large Publication Tasks with Short Flow Times.

    ERIC Educational Resources Information Center

    Santa, Terry M. Dalla

    Large publication tasks with short flow times require that several editors be assigned to work together as part of a larger publication team that includes management, engineer-writers, publishing logistics personnel, word processor operators, illustrators, and printers. Team-edited publications have special problems, and the technical editing and…

  17. SHORT-TIME KURTOSIS OF SPEECH SIGNALS WITH APPLICATION TO CO-CHANNEL SPEECH SEPARATION

    E-print Network

    De Leon, Phillip

    SHORT-TIME KURTOSIS OF SPEECH SIGNALS WITH APPLICATION TO CO-CHANNEL SPEECH SEPARATION Phillip L, New Mexico 88003-8001 pdeleon@nmsu.edu ABSTRACT Recent work into the separation of mixtures of speech, a simple gradient search algorithm is em- ployed to maximize kurtosis thereby separating the source speech

  18. APPARATUS FOR SHORT TIME MEASUREMENTS IN A FIXED-BED, GAS/SOLID REACTOR

    EPA Science Inventory

    An apparatus for exposure of a solid to reactive process gas is described which makes possible short time (? 0.3 to 15 s) exposures in a fixed-bed reactor. Operating conditions for differential reaction with respect to the gas concentration and rapid quench for arresting hi...

  19. Iterative reconstruction of speech from short-time Fourier transform phase and magnitude spectra

    E-print Network

    Iterative reconstruction of speech from short-time Fourier transform phase and magnitude spectra dimensional, signal reconstruction (specifically speech signals) from the magnitude spectrum and the phase magnitude spectrum, and (iii) a signal can be reconstructed to within a scale factor from its magnitude

  20. PHYSICAL REVIEW E 84, 031932 (2011) Short-time evolution in the adaptive immune system

    E-print Network

    Dinner, Aaron

    2011-01-01

    PHYSICAL REVIEW E 84, 031932 (2011) Short-time evolution in the adaptive immune system Nicholas as a whole is considered to have failed. This situation is seen in the adaptive immune system. During and it can then be amplified after reduction of the mutation factor (as in the immune system

  1. Large volume recycling of oceanic lithosphere over short time scales: geochemical constraints from the Caribbean Large

    E-print Network

    Graham, David W.

    Large volume recycling of oceanic lithosphere over short time scales: geochemical constraints from with derivation from recycled oceanic crust, while the depleted lavas are derived from a highly residual source source mantle could have been 9 500 Ma before CLIP formation and interpreted to reflect the recycling

  2. Photoinduced electron transfer and geminate recombination in liquids on short time scales: Experiments and theory

    E-print Network

    Fayer, Michael D.

    Photoinduced electron transfer and geminate recombination in liquids on short time scales 23 February 2006 The coupled processes of intermolecular photoinduced forward electron transfer of the donor excited state due to forward electron transfer and the survival kinetics of the radicals produced

  3. EUROGRAPHICS 2002 / N.N. Short Presentations Real Time Animated Grass

    E-print Network

    Heidrich, Wolfgang

    EUROGRAPHICS 2002 / N.N. Short Presentations Real Time Animated Grass Brook Bakay1 2 , Paul,heidrich¢ @cs.ubc.ca,lalonde@ea.com Abstract We present a simple method to render fields of grass, animated vector while preserving the length of the blades of grass. This technique achieves convincing results

  4. New methods for regulating flowering time in short-day strawberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Higher percentages of transplants of short-day cultivars 'Chandler', 'Carmine', 'Strawberry Festival', and 'Sweet Charlie' from runner tips plugged in early July rather than the standard time (early August) bloomed in the fall. Nearly 100% of the transplants produced in early July flowered in the f...

  5. Wavelets as alternative to short-time Fourier transform in signal-averaged electrocardiography.

    PubMed

    Gramatikov, B; Georgiev, I

    1995-05-01

    The paper reports experience of using the wavelet transform to build time-frequency distributions of the terminal portion of the QRS-complex. We used wavelets of Morlet at 12 scales, grouped in three sets, to analyse the frequency range 33-404 Hz. On the same patient data we applied the short-time Fourier transform and compared the results. Both representations reflected the time-frequency contents and detected irregular structures in the terminal portion of the QRS complex. The wavelet transform revealed more adequately QRS prolongations characteristic of patients prone to ventricular tachycardia. We may conclude that the wavelet transform can be a flexible alternative to short-time Fourier transform. PMID:7666698

  6. Long-time signatures of short-time dynamics in decaying quantum-chaotic systems

    E-print Network

    T. Gorin; D. F. Martinez; H. Schomerus

    2006-06-27

    We analyze the decay of classically chaotic quantum systems in the presence of fast ballistic escape routes on the Ehrenfest time scale. For a continuous excitation process, the form factor of the decay cross section deviates from the universal random-matrix result on the Heisenberg time scale, i.e. for times much larger than the time for ballistic escape. We derive an exact analytical description and compare our results with numerical simulations for a dynamical model.

  7. Correlation transfer in stochastically driven neural oscillators over long and short time scales.

    PubMed

    Abouzeid, Aushra; Ermentrout, Bard

    2011-12-01

    In the absence of synaptic coupling, two or more neural oscillators may become synchronized by virtue of the statistical correlations in their noisy input streams. Recent work has shown that the degree of correlation transfer from input currents to output spikes depends not only on intrinsic oscillator dynamics, but also on the length of the observation window over which the correlation is calculated. In this paper we use stochastic phase reduction and regular perturbations to derive the correlation of the total phase elapsed over long time scales, a quantity that provides a convenient proxy for the spike count correlation. Over short time scales, we derive the spike count correlation directly using straightforward probabilistic reasoning applied to the density of the phase difference. Our approximations show that output correlation scales with the autocorrelation of the phase resetting curve over long time scales. We also find a concise expression for the influence of the shape of the phase resetting curve on the initial slope of the output correlation over short time scales. These analytic results together with numerical simulations provide new intuitions for the recent counterintuitive finding that type I oscillators transfer correlations more faithfully than do type II over long time scales, while the reverse holds true for the better understood case of short time scales. PMID:22304123

  8. A short-time fading study of Al2O3:C

    NASA Astrophysics Data System (ADS)

    Nascimento, L. F.; Vanhavere, F.; Silva, E. H.; Deene, Y. De

    2015-01-01

    This paper studies the short-time fading from Al2O3:C by measuring optically stimulated luminescence (OSL) signals (Total OSL: TOSL, and Peak OSL: POSL) from droplets and Luxel™ pellets. The influence of various bleaching regimes (blue, green and white) and light power is compared. The fading effect is the decay of the OSL signal in the dark at room temperature. Al2O3:C detectors were submitted to various bleaching regimes, irradiated with a reference dose and read out after different time spans. Investigations were carried out using 2 mm size droplet detectors, made of thin Al2O3:C powder mixed with a photocured polymer. Tests were compared to Luxel™-type detectors (Landauer Inc.). Short-time post-irradiation fading is present in OSL results (TOSL and POSL) droplets for time spans up to 200 s. The effect of short-time fading can be lowered/removed when treating the detectors with high-power and/or long time bleaching regimes; this result was observed in both TOSL and POSL from droplets and Luxel™.

  9. Time-resolved measurement of photon states using two-photon interference with photons from short-time reference pulses

    E-print Network

    Changliang Ren; Holger F. Hofmann

    2011-06-01

    To fully utilize the energy-time degree of freedom of photons for optical quantum information processes, it is necessary to control and characterize the quantum states of the photons at extremely short time scales. For measurements beyond the time resolution of available detectors, two-photon interference with a photon in a short time reference pulse may be a viable alternative. In this paper, we derive the temporal measurement operators for the bunching statistics of a single photon input state with a reference photon. It is shown that the effects of the pulse shape of the reference pulse can be expressed in terms of a spectral filter selecting the bandwidth within which the measurement can be treated as an ideal projection on eigenstates of time. For full quantum tomography, temporal coherence can be determined by using superpositions of reference pulses at two different times. Moreover, energy-time entanglement can be evaluated based on the two-by-two entanglement observed in the coherences between pairs of detection times.

  10. Short-Time Glassy Dynamics in Viscous Protein Solutions with Competing Interactions

    NASA Astrophysics Data System (ADS)

    Godfrin, P. Douglas; Hudson, Steven D.; Hong, Kunlun; Porcar, Lionel; Falus, Peter; Wagner, Norman J.; Liu, Yun

    2015-11-01

    The glass transition of colloidal dispersions interacting with both a short-ranged attraction and long-ranged repulsion is studied using highly purified lysozyme solutions. Newtonian liquid behavior is observed at all conditions while measurements of the dynamics in the short-time limit show features typical of glassy colloidal systems at high protein concentrations. This interesting behavior is due to the competition of the attraction and repulsion that produces a heterogeneous microstructure only at intermediate range length scales. The results demonstrate that theories for the macroscopic properties of systems with competing interactions need to include intermediate range order.

  11. Short-duration low-gravity experiments - Time scales, challenges and results

    NASA Technical Reports Server (NTRS)

    Rosenberger, F.

    1993-01-01

    Short-duration low-gravity experiments can be conducted either in drop tubes and drop towers, or on sounding rockets and aircraft on ballistic trajectories. While these facilities offer more frequent flight opportunities and higher cost effectiveness than orbiting spacecraft, their relatively short low-gravity times are often perceived as limiting their utility to only a narrow range of applications and research areas. In this review it is shown, based on scaling laws for diffusive transport of momentum, species and heat, radiative heat transfer and capillarity-driven motion, that with proper consideration of the characteristic length scales, a host of phenomena can be meaningfully investigated during a few seconds. This usefulness of short-duration low-gravity facilities is illustrated with numerous results of recent studies of solidification, combustion, transport in multiphase systems, statics and dynamics of liquid surfaces, magnetic Benard convection, fluid management, transport properties and the graviperception in cells.

  12. Short time-scale variability of chromospheric Ca II in late-type stars

    NASA Technical Reports Server (NTRS)

    Baliunas, S. L.; Vaughan, A. H.; Hartmann, L.; Liller, W.; Dupree, A. K.

    1981-01-01

    The short time-scale variability of singly ionized calcium chromospheric emission has been investigated in a few late-type stars. Emission-line variations with time scales of a few minutes to hours are seen in Alpha Tau (K5 III), Lambda And (G8 III-IV), and Epsilon Eri (K2 V). The existence of substantial chromospheric flux changes (10 to the 30th to 10 to the 32nd ergs) over short periods of time suggests that the calcium emission arises from a few small, coherent regions. Frequencies present in the data are discussed in the context of acoustic wave predictions and estimated acoustic cutoff frequencies for giants and dwarfs.

  13. 78 FR 48199 - Comment Request for Information Collection for Employers Survey of the Short-Time Compensation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-07

    ... Short-Time Compensation Program (STC); New Collection AGENCY: Employment and Training Administration... data can be provided in the desired format, reporting burden (time and financial resources) is... Short-Time Compensation Program. OMB Number: 1205-0NEW. Affected Public: Private Sector,...

  14. Tel1ATM dictates the replication timing of short yeast telomeres.

    PubMed

    Cooley, Carol; Davé, Anoushka; Garg, Mansi; Bianchi, Alessandro

    2014-10-01

    Telomerase action is temporally linked to DNA replication. Although yeast telomeres are normally late replicating, telomere shortening leads to early firing of subtelomeric DNA replication origins. We show that double-strand breaks flanked by short telomeric arrays cause origin firing early in S phase at late-replicating loci and that this effect on origin firing time is dependent on the Tel1(ATM) checkpoint kinase. The effect of Tel1(ATM) on telomere replication timing extends to endogenous telomeres and is stronger than that elicited by Rif1 loss. These results establish that Tel1(ATM) specifies not only the extent but also the timing of telomerase recruitment. PMID:25122631

  15. NeuroQuantology | March 2009 | Vol 7 | Issue 1 | Page 138-151 Glicksohn J. Time production and EEG alpha revisited

    E-print Network

    Donchin, Opher

    Revisited Joseph Glicksohn* , Aviva Berkovich Ohana Tal Balaban Dotan , Abraham Goldstein , Opher Donchin posited, what Corresponding author: Joseph Glicksohn, Ph.D. Address:*Department of Criminology, Bar

  16. Short-time movement of E. coli chromosomal loci depends on coordinate and subcellular localization.

    PubMed

    Javer, Avelino; Long, Zhicheng; Nugent, Eileen; Grisi, Marco; Siriwatwetchakul, Kamin; Dorfman, Kevin D; Cicuta, Pietro; Cosentino Lagomarsino, Marco

    2013-01-01

    In bacteria, chromosomal architecture shows strong spatial and temporal organization, and regulates key cellular functions, such as transcription. Tracking the motion of chromosomal loci at short timescales provides information related to both the physical state of the nucleo-protein complex and its local environment, independent of large-scale motions related to genome segregation. Here we investigate the short-time (0.1-10?s) dynamics of fluorescently labelled chromosomal loci in Escherichia coli at different growth rates. At these timescales, we observe for the first time a dependence of the loci's apparent diffusion on both their subcellular localization and chromosomal coordinate, and we provide evidence that the properties of the chromosome are similar in the tested growth conditions. Our results indicate that either non-equilibrium fluctuations due to enzyme activity or the organization of the genome as a polymer-protein complex vary as a function of the distance from the origin of replication. PMID:23764719

  17. Use of short-time NH3 gas flow during Al milling

    NASA Astrophysics Data System (ADS)

    Caballero, E. S.; Cintas, J.; Cuevas, F. G.; Montes, J. M.; Herrera-García, M.

    2013-12-01

    Samples from mechanically alloyed aluminium powder were prepared by a simple press and sintering method in order to study the influence of a flow of ammonia gas during a short time of the milling process. All milling experiences were carried out at room temperature for a total of 10 hours. Millings were carried out in vacuum or under confined ammonia. This last type allows to incorporate nitrogen-rich second phases, mainly aluminium nitride (Al3CON) and oxynitride (Al5O6N), after powder sintering. To control the amounts of the second phases, a new milling type, using ammonia gas flow during 5 minutes followed by vacuum milling, was carried out. Testing of sintered samples shows that milling using ammonia, both confined and in flow, substantially improves mechanical properties. Furthermore, the use of a very short time gas flow allows obtaining compacts with similar tensile strength (485 MPa) to those obtained after milling in confined ammonia for 10 h.

  18. Short-time dynamics at a conical intersection in high-harmonic spectroscopy.

    PubMed

    Patchkovskii, Serguei; Schuurman, Michael S

    2014-12-26

    High-harmonic spectroscopy probes molecular dynamics using electrons liberated from the same molecule earlier in the laser cycle. It affords sub-Ångstrom spatial and subfemtosecond temporal resolution. Nuclear dynamics in the intermediate cation influence the spectrum of the emitted high-harmonic photons through an autocorrelation function. Here, we develop an analytical approach for computing short-time nuclear autocorrelation functions in the vicinity of conical intersections, including laser-induced and nonadiabatic coupling between the surfaces. We apply the technique to two molecules of current experimental interest, C6H6 and C6H5F. In both molecules, high-harmonics generated within the same electronic channel are not sensitive to nonadiabatic dynamics, even in the presence of substantial population transfer. Calculated autocorrelation functions exhibit significant deviations from the expected Gaussian decay and may undergo revivals at short (?1.5 fs) times. The associated phase of the nuclear wavepacket provides a possible experimental signature. PMID:25314638

  19. Short contact time direct coal liquefaction using a novel batch reactor. Quarterly report, 1996

    SciTech Connect

    Klein, M.T.; Calkins, W.H.; Huang, H.

    1996-05-01

    The objective of this research is to optimize the design and operation of the bench scale batch reactor (SCTBR) for coal liquefaction at short contact times (0.01 to 10 minutes or longer). Additional objectives are to study the kinetics of direct coal liquefaction particularly at short reaction times, and to investigate the role of the organic oxygen components of coal and their reaction pathways during liquefaction. Many of those objectives have already been achieved and others are still in progress. This quarterly report covers further progress toward those objectives. Much of the previous quarterly report was concerned mainly in the retrograde reactions occurring during the liquefaction process. This report is largely devoted to the kinetics and mechanisms of the liquefaction process itself and the influence of the liquefaction solvents.

  20. Short-time Lyapunov exponent analysis and the transition to chaos in Taylor-Couette flow

    NASA Technical Reports Server (NTRS)

    Vastano, John A.; Moser, Robert D.

    1991-01-01

    The physical mechanism driving the weakly chaotic Taylor-Couette flow is investigated using the short-time Liapunov exponent analysis. In this procedure, the transition from quasi-periodicity to chaos is studied using direct numerical 3D simulations of axially periodic Taylor-Couette flow, and a partial Liapunov exponent spectrum for the flow is computed by simultaneously advancing the full solution and a set of perturbations. It is shown that the short-time Liapunov exponent analysis yields more information on the exponents and dimension than that obtained from the common Liapunov exponent calculations. Results show that the chaotic state studied here is caused by a Kelvin-Helmholtz-type instability of the outflow boundary jet of Taylor vortices.

  1. Short-time dynamics of the three-dimensional fully frustrated Ising model

    NASA Astrophysics Data System (ADS)

    Mutailamov, V. A.; Murtazaev, A. K.

    2015-07-01

    The critical relaxation from the low-temperature ordered state of the three-dimensional fully frustrated Ising model on a simple cubic lattice has been studied using the short-time dynamics method. Particles with the periodic boundary conditions containing N = 262144 spins have been studied. Calculations have been performed by the standard Metropolis Monte Carlo algorithm. The static critical exponents of the magnetization and correlation radius have been obtained. The dynamic critical exponent of the model under study has been calculated.

  2. Short-Time Kinetics and Initial Correlations in Quantum Kinetic Theory

    E-print Network

    Bonitz, Michael

    approximation I(p1RT) = 2 dp2d¯p1d¯p2 (2 )9 2 E12 - ¯E12 p1p2| T+ (E12 + i) |¯p2 ¯p1 2 × ¯f1 ¯f2 (1 ± f1) (1 ± f. This was pointed out already by Prigogine and Resibois [1], Kadanoff and Baym [2], Silin [3] and especially by Klimontovich [4]. The Boltzmann equation (i) cannot describe the short-time behavior (t

  3. Internal dynamics of proteins. Short time and long time motions of aromatic sidechains in PTI.

    PubMed Central

    Karplus, M; Gelin, B R; McCammon, J A

    1980-01-01

    Theoretical approaches to the internal dynamics of proteins are outlined and illustrated by application to the aromatic sidechain motions of tyrosines in the bovine pancreatic trypsin inhibitor. High frequency torsional oscillations are obtained from a molecular dynamics simulation, while the longer time ring rotations are analyzed by use of adiabatic energy minimization and special transition-state trajectory techniques. PMID:7248464

  4. The short-term prediction of universal time and length of day using atmospheric angular momentum

    NASA Technical Reports Server (NTRS)

    Freedman, A. P.; Steppe, J. A.; Dickey, J. O.; Eubanks, T. M.; Sung, L.-Y.

    1994-01-01

    The ability to predict short-term variations in the Earth's rotation has gained importance in recent years owing to more precise spacecraft tracking requirements. Universal time (UT1), that component of the Earth's orientation corresponding to the rotation angle, can be measured by number of high-precision space geodetic techniques. A Kalman filter developed at the Jet Propulsion Laboratory (JPL) optimally combines these different data sets and generates a smoothed times series and a set of predictions for UT1, as well as for additional Earth orientation components. These UT1 predictions utilize an empirically derived random walk stochastic model for the length of the day (LOD) and require frequent and up-to-date measurements of either UT1 or LOD to keep errors from quickly accumulating. Recent studies have shown that LOD variations are correlated with changes in the Earth's axial atmospheric angular momentum (AAM) over timescales of several years down to as little as 8 days. AAM estimates and forecasts out to 10 days are routinely available from meteorological analysis centers; these data can supplement geodetic measurements to improve the short-term prediction of LOD and have therefore been incorporated as independent data types in the JPL Kalman filter. We find that AAM and, to a lesser extent, AAM forecast data are extremely helpful in generating accurate near-real-time estimates of UT1 and LOD and in improving short-term predictions of these quantities out to about 10 days.

  5. Quantifying complexity of financial short-term time series by composite multiscale entropy measure

    NASA Astrophysics Data System (ADS)

    Niu, Hongli; Wang, Jun

    2015-05-01

    It is significant to study the complexity of financial time series since the financial market is a complex evolved dynamic system. Multiscale entropy is a prevailing method used to quantify the complexity of a time series. Due to its less reliability of entropy estimation for short-term time series at large time scales, a modification method, the composite multiscale entropy, is applied to the financial market. To qualify its effectiveness, its applications in the synthetic white noise and 1 / f noise with different data lengths are reproduced first in the present paper. Then it is introduced for the first time to make a reliability test with two Chinese stock indices. After conducting on short-time return series, the CMSE method shows the advantages in reducing deviations of entropy estimation and demonstrates more stable and reliable results when compared with the conventional MSE algorithm. Finally, the composite multiscale entropy of six important stock indices from the world financial markets is investigated, and some useful and interesting empirical results are obtained.

  6. Galilei general relativistic quantum mechanics revisited

    E-print Network

    JanyÂ?ka, Josef

    Galilei general relativistic quantum mechanics revisited Arkadiusz Jadczyk Institute of Theoretical of Galilei relativistic quantum mechanics. The main concepts used are Galilei­Newton space­time, Newtonian : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 22 1.9 Classical particle mechanics : : : : : : : : : : : : : : : : : : : : : : : : 22 2 Quantum

  7. SLIM--An Early Work Revisited

    SciTech Connect

    Chao, Alex; /SLAC

    2008-07-25

    An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981.

  8. Localized proton NMR spectroscopy of brain tumors using short-echo time STEAM sequences.

    PubMed

    Frahm, J; Bruhn, H; Hänicke, W; Merboldt, K D; Mursch, K; Markakis, E

    1991-01-01

    Recent progress in localized proton NMR spectroscopy has been utilized to improve the spatial resolution and the metabolic specificity in a study of 19 patients with intracranial tumors. Selected examples demonstrate that short echo time stimulated echo acquisition mode sequences are able (a) to account for macroscopic tissue heterogeneity by reducing the volume of interest to 2-8 ml and (b) to facilitate a reasonable characterization of tumor metabolism by increasing the number of accessible metabolites. Proton NMR spectra were acquired within measuring times of 6.5 min on a 2.0 T whole-body system using the imaging headcoil. PMID:1939768

  9. On the Relative Importance of the Short-Time Magnitude and Phase Spectra Towards Speaker Dependent Information

    E-print Network

    On the Relative Importance of the Short-Time Magnitude and Phase Spectra Towards Speaker Dependent investigate the relative contribution of the short-time magnitude and phase spectra towards speaker dependent a human speaker verification experiment that uses phase-only and magnitude-only stimuli. The stimuli

  10. Autophagy exacerbates caspase-dependent apoptotic cell death after short times of starvation.

    PubMed

    Mattiolo, Paolo; Yuste, Victor J; Boix, Jacint; Ribas, Judit

    2015-12-15

    Autophagy is generally regarded as a mechanism to promote cell survival. However, autophagy can occasionally be the mechanism responsible of cell demise. We have found that a concomitant depletion of glucose, nutrients and growth factors provoked cell death in a variety of cell lines. This death process was contingent upon caspase activation and was mediated by BAX/BAK proteins, thus indicating its apoptotic nature and the engagement of an intrinsic pathway. In order to abrogate autophagy, 3-methyladenine (3-MA), BECLIN-1 siRNA and Atg5 knock-out (Tet-Off type) approaches were alternatively employed. Irrespective of the procedure, at short times of starvation, we found that the ongoing autophagy was sensitizing cells to the permeabilization of the mitochondrial outer membrane (MOMP), caspase activation and, therefore, apoptosis. On the contrary, at longer times of starvation, autophagy displayed its characteristic pro-survival effect on cells. As far as we know, we provide the first experimental paradigm where time is the only variable determining the final outcome of autophagy. In other words, we have circumscribed in time the shift transforming autophagy from a cell death to a protection mechanism. Moreover, at short times, starvation-driven autophagy exacerbated the apoptotic cell death caused by several antitumor agents. In agreement with this fact, their apoptotic effects were greatly diminished by autophagy inhibition. The implications of these facts in tumor biology will be discussed. PMID:26441250

  11. Nonlinear response of vessel walls due to short-time thermomechanical loading

    SciTech Connect

    Pfeiffer, P.A.; Kulak, R.F.

    1994-06-01

    Maintaining structural integrity of the reactor pressure vessel (RPV) during a postulated core melt accident is an important safety consideration in the design of the vessel. This study addresses the failure predictions of the vessel due to thermal and pressure loadings fro the molten core debris depositing on the lower head of the vessel. Different loading combinations were considered based on the dead load, yield stress assumptions, material response and internal pressurization. The analyses considered only short term failure (quasi static) modes, long term failure modes were not considered. Short term failure modes include plastic instabilities of the structure and failure due to exceeding the failure strain. Long term failure odes would be caused by creep rupture that leads to plastic instability of the structure. Due to the sort time durations analyzed, creep was not considered in the analyses presented.

  12. Short-term foreshocks in Southern California and Italy revisited: Observed deviations from the Epidemic-Type Aftershock Sequence (ETAS) Model

    NASA Astrophysics Data System (ADS)

    Seif, Stefanie; Mignan, Arnaud; Wiemer, Stefan

    2013-04-01

    Numerous studies have suggested that short-term foreshocks observed prior to large earthquakes are undistinguishable from the normal behaviour of seismicity, which is well described for example by the Epidemic-Type Aftershock Sequence (ETAS) model. Here we show that these studies fail to extract abnormal foreshock behaviour due to the much more frequent occurrence of aftershocks in comparison to potential foreshocks, which results in undervaluing the role of foreshocks. We first define mainshocks as earthquakes of magnitude M6+ and use a space-time-magnitude window method with a maximum distance of 10 km to the mainshock, a maximum time range of 3 days before the mainshock and a minimum magnitude M4+ to define foreshocks in Southern California and in Italy. We then compare the observed rate of foreshock-mainshock pairs to the rate expected by ETAS simulations. Similar to previous studies, these results indicate that the foreshock activity observed in real catalogues is compatible with the ETAS model. Definition of foreshocks with a window method is, however, simplistic, since any individual event may be considered a foreshock although it is impossible to distinguish a foreshock from background or aftershock activity at a one-to-one event basis. We extend our foreshock analysis based on the predictions of the Non-Critical Precursory Accelerating Seismicity Theory (NC PAST), which are: (1) foreshocks are due to overloading on the main fault and occur in clusters, the activity of which is significantly higher than background activity, (2) microseismicity (M<3) must be included for the emergence of a reliable signal and (3) foreshocks are not systematic before large earthquakes due to aleatoric uncertainty on the rupture process. Following these guidelines, we systematically investigate foreshock sequences before large earthquakes (M6+) in Southern California and Italy. Using different approaches, we finally show that significant anomalies are observed before some mainshocks (e.g., 1992 Landers, 2009 L'Aquila earthquakes), which are not explained by the ETAS process. Anomalies are defined as any deviation from a Poissonian distribution (which describes the stationary background seismicity) with a Poisson probability lower than 10^-4. We use approaches such as heuristic (what if a large cluster of events is not preceded by any event large enough to produce such a cluster?), ETAS stochastic declustering and a nearest-neighbour cluster technique that differentiates between foreshocks, mainshocks and aftershocks. Our results highlight the shortcomings of current systematic precursory seismicity analyses: First, in order to consider a sufficient number of mainshocks, a large region is usually considered, which requires the use of a relatively high completeness magnitude. This considerably limits the significance of potential anomalies, which are mostly defined from microseismicity (according to the NC PAST). Second, it is commonly assumed that all mainshocks behave the same (in agreement with the ETAS process), which would validate stacking/averaging over multiple sequences. This approach however fails if mainshocks behave differently from one to another (according to the NC PAST). To conclude, microseismicity and non-systematic presence of anomalies are key conditions to better understand potential foreshocks before large earthquakes, their physical origin and their potential role in time-dependent hazard assessment and earthquake prediction.

  13. Modeling circadian and sleep-homeostatic effects on short-term interval timing

    PubMed Central

    Späti, Jakub; Aritake, Sayaka; Meyer, Andrea H.; Kitamura, Shingo; Hida, Akiko; Higuchi, Shigekazu; Moriguchi, Yoshiya; Mishima, Kazuo

    2015-01-01

    Short-term interval timing i.e., perception and action relating to durations in the seconds range, has been suggested to display time-of-day as well as wake dependent fluctuations due to circadian and sleep-homeostatic changes to the rate at which an underlying pacemaker emits pulses; pertinent human data being relatively sparse and lacking in consistency however, the phenomenon remains elusive and its mechanism poorly understood. To better characterize the putative circadian and sleep-homeostatic effects on interval timing and to assess the ability of a pacemaker-based mechanism to account for the data, we measured timing performance in eighteen young healthy male subjects across two epochs of sustained wakefulness of 38.67 h each, conducted prior to (under entrained conditions) and following (under free-running conditions) a 28 h sleep-wake schedule, using the methods of duration estimation and duration production on target intervals of 10 and 40 s. Our findings of opposing oscillatory time courses across both epochs of sustained wakefulness that combine with increasing and, respectively, decreasing, saturating exponential change for the tasks of estimation and production are consistent with the hypothesis that a pacemaker emitting pulses at a rate controlled by the circadian oscillator and increasing with time awake determines human short-term interval timing; the duration-specificity of this pattern is interpreted as reflecting challenges to maintaining stable attention to the task that progressively increase with stimulus magnitude and thereby moderate the effects of pacemaker-rate changes on overt behavior. PMID:25741253

  14. Hyperferritinemia is associated with short survival time in dogs with multicentric lymphoma

    PubMed Central

    CHIKAZAWA, Seishiro; HORI, Yasutomo; HOSHI, Fumio; KANAI, Kazutaka; ITO, Naoyuki

    2015-01-01

    In the present study, we examined the relationship between serum ferritin concentration before treatment and survival time in dogs with multicentric lymphoma. Eighteen dogs with multicentric lymphoma were enrolled in the study. When the dogs were classified into high and low ferritin groups on the basis of their serum ferritin concentration (3,000 ng/ml cut-off value), the median survival time of dogs with high concentrations (?3,000 ng/ml, n=7) was 40 days, whereas it was 360 days among dogs with low concentrations (<3,000 ng/ml, n=11). This difference was statistically significant (P=0.001). This finding suggests that the initial high level of serum ferritin indicates short survival time in dogs with multicentric lymphoma. Large-scale research is necessary to confirm this finding. PMID:25715650

  15. Thick-target bremsstrahlung interpretation of short time-scale solar hard X-ray features

    NASA Technical Reports Server (NTRS)

    Emslie, A. G.

    1983-01-01

    Steady-state analyses of bremsstrahlung hard X-ray production in solar flares are appropriate only if the lifetime of the high energy electrons in the X-ray source is much shorter than the duration of the observed X-ray burst. For a thick-target nonthermal model, this implies that a full time-dependent analysis is required when the duration of the burst is comparable to the collisional lifetime of the injected electrons, in turn set by the lengths and densities of the flaring region. In this paper we present the results of such a time-dependent analysis, and we point out that the intrinsic temporal signature of the thick-target production mechanism, caused by the finite travel time of the electrons through the target, may indeed rule out such a mechanism for extremely short duration hard X-ray events.

  16. Detection of central fixation using short-time autoregressive spectral estimation during retinal birefringence scanning.

    PubMed

    Gramatikov, Boris I

    2015-09-01

    The manuscript reports on the implementation of autoregressive spectral estimation aimed at improving the accuracy of detecting short-lasting events in signals acquired by a retinal birefringence scanning device that was reported earlier. A signal consisting of two frequency components is generated, where each frequency is a multiple of the scanning frequency. One frequency is produced during central fixation, while another one prevails during off-central fixation. These components may be of a very short duration, presenting a challenge for the FFT to identify them with sufficient time- and frequency resolution. Autoregressive spectral estimation using the Burg algorithm provided a satisfactory solution, capable of reliably differentiating between the two frequency components (96 and 192 Hz) on signal segments of duration as short as 5 ms. The device and the signal analysis methods were developed originally with the purpose of checking for eye alignment and strabismus - a major risk factor for amblyopia. The method enables the technology to work with less-cooperative patients, such as young children. Other medical and non-medical applications are possible. PMID:26213271

  17. Characterization of the complexity in short oscillating time series: An application to seismic airgun detonations.

    PubMed

    Miralles, R; Carrión, A; Looney, D; Lara, G; Mandic, D

    2015-09-01

    Extracting frequency-derived parameters allows for the identification and characterization of acoustic events, such as those obtained in passive acoustic monitoring applications. Situations where it is difficult to achieve the desired frequency resolution to distinguish between similar events occur, for example, in short time oscillating events. One feasible approach to make discrimination among such events is by measuring the complexity or the presence of non-linearities in a time series. Available techniques include the delay vector variance (DVV) and recurrence plot (RP) analysis, which have been used independently for statistical testing, however, the similarities between these two techniques have so far been overlooked. This work suggests a method that combines the DVV method with the recurrence quantification analysis parameters of the RP graphs for the characterization of short oscillating events. In order to establish the confidence intervals, a variant of the pseudo-periodic surrogate algorithm is proposed. This allows one to eliminate the fine details that may indicate the presence of non-linear dynamics, without having to add a large amount of noise, while preserving more efficiently the phase-space shape. The algorithm is verified on both synthetic and real world time series. PMID:26428796

  18. Short Contact Time Direct Coal Liquefaction Using a Novel Batch Reactor

    SciTech Connect

    He Huang; Michael T. Klein; William H. Calkins

    1997-04-03

    The primary objective of this research is to optimize the design and operation of the bench scale batch reactor (SCTBR) for studying direct coal liquefaction at short contact times (.01 to 10 minutes or longer) . An additional objective is to study the kinetics of direct coal liquefaction particularly at short reaction times. Both of these objectives have been nearly achieved, however this work has shown the great importance of the liquefaction solvent characteristics and the solvent-catalyst interaction on the liquefaction process. This has prompted us to do a preliminary investigation of solvents and the solvent-catalyst systems in coal liquefaction. SUMMARY AND CONCLUSIONS 1) Conversion vs time data have been extended to 5 coals of ranks from lignite to low volatile bituminous coal. A broad range of reaction rates have been observed with a maximum in the high volatile bituminous range. 2) A series of direct coal liquefaction runs have been made using a range of nitrogen containing solvents that given high liquefaction conversions of coal. These runs are now being analyzed. 3) The coalification process has been shown by TGA to go through an intermediate stage which may account for the greater reactivity of bituminous coals in the direct coal liquefaction process. 4) It was shown that coal rank can be accurately determined by thermogravimetric analysis

  19. Noninvasive assessment of arterial compliance of human cerebral arteries with short inversion time arterial spin labeling

    PubMed Central

    Warnert, Esther AH; Murphy, Kevin; Hall, Judith E; Wise, Richard G

    2015-01-01

    A noninvasive method of assessing cerebral arterial compliance (AC) is introduced in which arterial spin labeling (ASL) is used to measure changes in arterial blood volume (aBV) occurring within the cardiac cycle. Short inversion time pulsed ASL (PASL) was performed in healthy volunteers with inversion times ranging from 250 to 850?ms. A model of the arterial input function was used to obtain the cerebral aBV. Results indicate that aBV depends on the cardiac phase of the arteries in the imaging volume. Cerebral AC, estimated from aBV and brachial blood pressure measured noninvasively in systole and diastole, was assessed in the flow territories of the basal cerebral arteries originating from the circle of Willis: right and left middle cerebral arteries (RMCA and LMCA), right and left posterior cerebral arteries (RPCA and LPCA), and the anterior cerebral artery (ACA). Group average AC values calculated for the RMCA, LMCA, ACA, RPCA, and LPCA were 0.56%±0.2%, 0.50%±0.3%, 0.4%±0.2%, 1.1%±0.5%, and 1.1%±0.3% per mm?Hg, respectively. The current experiment has shown the feasibility of measuring AC of cerebral arteries with short inversion time PASL. PMID:25515216

  20. Short-Time Operator Product Expansion for rf Spectroscopy of a Strongly Interacting Fermi Gas

    SciTech Connect

    Braaten, Eric; Kang, Daekyoung; Platter, Lucas

    2010-06-04

    Universal relations that hold for any state provide powerful constraints on systems consisting of fermions with two spin states interacting with a large scattering length. In radio-frequency (rf) spectroscopy, the mean shift in the rf frequency and the large-frequency tail of the rf transition rate are proportional to the contact, which measures the density of pairs with small separations. We show that these universal relations can be derived and extended by using the short-time operator product expansion of quantum field theory. This is a general method for identifying aspects of many-body physics that are controlled by few-body physics.

  1. Fast detection of nonlinearity and nonstationarity in short and noisy time series

    E-print Network

    M. De Domenico; V. Latora

    2010-07-07

    We introduce a statistical method to detect nonlinearity and nonstationarity in time series, that works even for short sequences and in presence of noise. The method has a discrimination power similar to that of the most advanced estimators on the market, yet it depends only on one parameter, is easier to implement and faster. Applications to real data sets reject the null hypothesis of an underlying stationary linear stochastic process with a higher confidence interval than the best known nonlinear discriminators up to date.

  2. Time of flight emission spectroscopy of laser produced nickel plasma: Short-pulse and ultrafast excitations

    NASA Astrophysics Data System (ADS)

    Smijesh, N.; Chandrasekharan, K.; Joshi, Jagdish C.; Philip, Reji

    2014-07-01

    We report the experimental investigation and comparison of the temporal features of short-pulse (7 ns) and ultrafast (100 fs) laser produced plasmas generated from a solid nickel target, expanding into a nitrogen background. When the ambient pressure is varied in a large range of 10-6 Torr to 102 Torr, the plume intensity is found to increase rapidly as the pressure crosses 1 Torr. Time of flight (TOF) spectroscopy of emission from neutral nickel (Ni I) at 361.9 nm (3d9(2D) 4p ? 3d9(2D) 4s transition) reveals two peaks (fast and slow species) in short-pulse excitation and a single peak in ultrafast excitation. The fast and slow peaks represent recombined neutrals and un-ionized neutrals, respectively. TOF emission from singly ionized nickel (Ni II) studied using the 428.5 nm (3p63d8(3P) 4s? 3p63d9 4s) transition shows only a single peak for either excitation. Velocities of the neutral and ionic species are determined from TOF measurements carried out at different positions (i.e., at distances of 2 mm and 4 mm, respectively, from the target surface) on the plume axis. Measured velocities indicate acceleration of neutrals and ions, which is caused by the Coulomb pull of the electrons enveloping the plume front in the case of ultrafast excitation. Both Coulomb pull and laser-plasma interaction contribute to the acceleration in the case of short-pulse excitation. These investigations provide new information on the pressure dependent temporal behavior of nickel plasmas produced by short-pulse and ultrafast laser pulses, which have potential uses in applications such as pulsed laser deposition and laser-induced nanoparticle generation.

  3. Time of flight emission spectroscopy of laser produced nickel plasma: Short-pulse and ultrafast excitations

    SciTech Connect

    Smijesh, N.; Chandrasekharan, K.; Joshi, Jagdish C.; Philip, Reji

    2014-07-07

    We report the experimental investigation and comparison of the temporal features of short-pulse (7 ns) and ultrafast (100 fs) laser produced plasmas generated from a solid nickel target, expanding into a nitrogen background. When the ambient pressure is varied in a large range of 10??Torr to 10²Torr, the plume intensity is found to increase rapidly as the pressure crosses 1 Torr. Time of flight (TOF) spectroscopy of emission from neutral nickel (Ni I) at 361.9 nm (3d?(²D) 4p ? 3d?(²D) 4s transition) reveals two peaks (fast and slow species) in short-pulse excitation and a single peak in ultrafast excitation. The fast and slow peaks represent recombined neutrals and un-ionized neutrals, respectively. TOF emission from singly ionized nickel (Ni II) studied using the 428.5 nm (3p?3d?(³P) 4s? 3p?3d? 4s) transition shows only a single peak for either excitation. Velocities of the neutral and ionic species are determined from TOF measurements carried out at different positions (i.e., at distances of 2 mm and 4 mm, respectively, from the target surface) on the plume axis. Measured velocities indicate acceleration of neutrals and ions, which is caused by the Coulomb pull of the electrons enveloping the plume front in the case of ultrafast excitation. Both Coulomb pull and laser-plasma interaction contribute to the acceleration in the case of short-pulse excitation. These investigations provide new information on the pressure dependent temporal behavior of nickel plasmas produced by short-pulse and ultrafast laser pulses, which have potential uses in applications such as pulsed laser deposition and laser-induced nanoparticle generation.

  4. Short-term earthquake risk assessment considering time-dependent b-values

    NASA Astrophysics Data System (ADS)

    Gulia, Laura; Tormann, Thessa; Wiemer, Stefan

    2015-04-01

    Observations from laboratory experiments measuring acoustic emissions during loading cycles in pressurized rock samples have repeatedly suggested that small events in the precursory phase of an impending large event change in their relative size distribution. In particular, they highlight a systematic b-value decrease during the stress increase period before the main event. A number of large natural events, but not all of them, have been shown to have a precursory decrease in the b-value at very different time scales, from months to a few days before the subsequent mainshock. At present short term-forecast models such as STEP and ETAS consider the generic probability that an event can trigger subsequent seismicity in the near field; the rate increasing during the foreshock sequences can offer a probability gain for a significant earthquake to happen. While the probability gain of a stationary Poissonian background is substantial, selected case studies have shown through cost-benefit analysis that the absolute probability remains too low to warrant actions. This was shown for example by van Stiphout et al. (2010, GRL), for the 2009 a Mw 6.3 earthquake that hit the city of L'Aquila (Central Italy) after three months of foreshock activity. We here analyze the probability gain of a novel generation of short term forecast models which considers both the change in the seismicity rates and the temporal changes in the b-value. Changes in earthquake probability are then translated also into time-dependent hazard and risk. Preliminary results suggest that the precursory b-value decrease in the L'Aquila case results in an additional probability increase of a M6.3 event of about a factor of 30-50, which then surpasses the cost-benefit threshold for short-term evacuation in selected cases.

  5. Short-time dynamics of Fe{sub 2}/V{sub 13} magnetic superlattice models

    SciTech Connect

    Murtazaev, A. K.; Mutailamov, V. A.

    2013-04-15

    Critical relaxation from a low-temperature fully ordered state of Fe{sub 2}/V{sub 13} iron-vanadium magnetic superlattice models has been studied using the method of short-time dynamics. Systems with three variants of the ratio R of inter-to intralayer exchange coupling have been considered. Particles with N = 262144 spins have been simulated with periodic boundary conditions. Calculations have been performed using the standard Metropolis algorithm of the Monte Carlo method. The static critical exponents of magnetization and correlation radius, as well as the dynamic critical exponent, have been calculated for three R values. It is established that a small decrease in the exchange ratio (from R = 1.0 to 0.8) does not significantly influence the character of the short-time dynamics in the models studied. A further significant decrease in this ratio (to R = 0.01), for which a transition from three-dimensional to quasi-two-dimensional magnetism is possible, leads to significant changes in the dynamic behavior of iron-vanadium magnetic superlattice models.

  6. An Optimal Mitigation Strategy Against the Asteroid Impact Threat with Short Warning Time

    NASA Technical Reports Server (NTRS)

    Wie, Bong; Barbee, Brent W.

    2015-01-01

    This paper presents the results of a NASA Innovative Advanced Concept (NIAC) Phase 2 study entitled "An Innovative Solution to NASA's Near-Earth Object (NEO) Impact Threat Mitigation Grand Challenge and Flight Validation Mission Architecture Development." This NIAC Phase 2 study was conducted at the Asteroid Deflection Research Center (ADRC) of Iowa State University in 2012-2014. The study objective was to develop an innovative yet practically implementable mitigation strategy for the most probable impact threat of an asteroid or comet with short warning time (less than 5 years). The mitigation strategy described in this paper is intended to optimally reduce the severity and catastrophic damage of the NEO impact event, especially when we don't have sufficient warning times for non-disruptive deflection of a hazardous NEO. This paper provides an executive summary of the NIAC Phase 2 study results.

  7. The short-time and long-time behaviors of non-Markovianity measure using two-time correlation functions in open quantum systems

    E-print Network

    Md. Manirul Ali; Ping-Yuan Lo; Matisse Wei-Yuan Tu; Wei-Min Zhang

    2015-05-21

    We investigate non-Markovianity measure using two-time correlation functions for open quantum systems. We define non-Markovianity measure as the difference between the exact two-time correlation function and the one obtained in the Markov limit. Such non-Markovianity measure can easily be measured in experiments. We found that the non-Markovianity dynamics in different time scale crucially depends on the system-environment coupling strength and other physical parameters such as the initial temperature of the environment and the initial state of the system. In particular, we obtain the short-time and long-time behaviors of non-Markovianity for different spectral densities. We also find that the thermal fluctuation always reduce the non-Markovian memory effect. Also, the non-Markovianity measure shows non-trivial initial state dependence in different time scales.

  8. Space Depends On Time: Informational Asymmetries in Visual and Auditory Short-Term Memory.

    PubMed

    Noyce, Abigail; Cestero, Nishmar; Shinn-Cunningham, Barbara; Somers, David

    2015-09-01

    Sensory modalities vary in adeptness for spatial and temporal information domains (Welch & Warren, 1980). Recent work suggests that attention and short-term memory (STM) recruit this variability (Michalka et al., submitted). Here, we investigate the relationships among visual and auditory modalities, and spatial and temporal STM. We developed stimuli comprising short sequences of visual events (instantaneous image changes) or auditory events (50ms complex tones). Each event within a sequence had a unique spatial location and a unique inter-event interval. These stimuli were used in a STM change-detection task. On each trial, two successive sequences were presented; a change could occur among the locations, the intervals, both, or neither. Subjects attended to either space (the sequence of locations), or time (the sequence of inter-event intervals), and reported whether the patterns of locations or intervals were identical. Each subject completed blocks of unimodal (both sequences presented in the same modality) and crossmodal (sequence 1 visual and sequence 2 auditory, or vice versa) trials for both tasks. We found a strong modality appropriateness effect, with best temporal performance on unimodal auditory trials, and best spatial performance on unimodal visual trials. The order of modalities on crossmodal trials mattered for space (benefit for visual sequence 1) but not for time, supporting a domain recruitment account of spatial STM. We also investigated cross-domain interactions by measuring whether instability of spatial location affected change detection for intervals, or vice versa. Changes in timing from sequence 1 to sequence 2 substantially impaired change detection for locations, while changes in locations did not impair change detection for intervals. These results suggest that spatial and temporal STM are asymmetrically related, such that timing information facilitates monitoring a series of locations, but spatial knowledge is unnecessary when monitoring a series of intervals. Meeting abstract presented at VSS 2015. PMID:26326742

  9. Effects of Diffusion Time on Short-Range Hyperpolarized 3He Diffusivity Measurements in Emphysema

    SciTech Connect

    Gierada, David S.; Woods, Jason C.; Bierhals, Andrew J.; Bartel, Seth T.; Ritter, Jon H.; Choong, Cliff K.; Das, Nitin A.; Hong, Cheng; Pilgram, Thomas K.; Chang, Yulin V.; Jacob, Rick E.; Hogg, James C.; Battafarano, Richard J.; Cooper, Joel D.; Meyers, Bryan F.; Patterson, G Alexander; Yablonskiy, Dmitriy A.; Conradi, Mark S.

    2009-09-28

    Purpose: To characterize the effect of diffusion time on short-range hyperpolarized 3He MR diffusion measurements across a wide range of emphysema severity. Materials and Methods: 3He diffusion MR imaging was performed on 19 lungs or lobes resected from 18 subjects with varying degrees of emphysema using 3 diffusion times (1.6 msec, 5 msec, and 10 msec) at constant b value. Emphysema severity was quantified as the mean apparent diffusion coefficient (ADC) and as the percentage of pixels with ADC higher than multiple thresholds from 0.30-0.55 cm2/sec (ADC index). Quantitative histology (mean linear intercept) was obtained in 10 of the lung specimens from 10 of the subjects. Results: The mean ADCs with diffusion times of 1.6, 5.0, and 10.0 msec were 0.46, 0.40, and 0.37 cm2/sec, respectively (P <0.0001, ANOVA). There was no relationship between the ADC magnitude and the effect of diffusion time on ADC values. Mean linear intercept correlated with ADC (r=0.91-0.94, P<0.001) and ADC index (r=0.78-0.92, P<0.01) at all diffusion times.

  10. EXPLORING THE POTENTIAL OF SHORT-TIME FOURIER TRANSFORMS FOR ANALYZING SKIN CONDUCTANCE AND PUPILLOMETRY IN REAL-TIME APPLICATIONS

    SciTech Connect

    Roger Lew; Brian P. Dyre; Steffen Werner; Jeffrey C. Joe; Brian Wotring; Tuan Tran

    2008-09-01

    The development of real-time predictors of mental workload is critical for the practical application of augmented cognition to human-machine systems. This paper explores a novel method based on a short-time Fourier transform (STFT) for analyzing galvanic skin conductance (SC) and pupillometry time-series data to extract estimates of mental workload with temporal bandwidth high-enough to be useful for augmented cognition applications. We tested the method in the context of a process control task based on the DURESS simulation developed by Vincente and Pawlak (1994; ported to Java by Cosentino,& Ross, 1999). SC, pupil dilation, blink rate, and visual scanning patterns were measured for four participants actively engaged in controlling the simulation. Fault events were introduced that required participants to diagnose errors and make control adjustments to keep the simulator operating within a target range. We were interested in whether the STFT of these measures would produce visible effects of the increase in mental workload and stress associated with these events. Graphical exploratory data analysis of the STFT showed visible increases in the power spectrum across a range of frequencies directly following fault events. We believe this approach shows potential as a relatively unobtrusive, low-cost, high bandwidth measure of mental workload that could be particularly useful for the application of augmented cognition to human-machine systems.

  11. Implementation practice of short-term load forecasting in time series

    SciTech Connect

    Fan, J.Y.

    1996-10-01

    This paper presents an implementation practice of real-time short-term load forecasting using time series model incorporated with a similar-day model. In the time series model, a comprehensive load model is developed by incorporating time series functions, nonlinear load-weather functions and a residual load function. The model parameters are estimated and updated on-line using the WRLS (weighted Recursive Least Squares) algorithm. A variable forgetting factor (VFF) technique is included in the WRLS algorithm for improved model tracking capability and numerical performance in real-time operation.The model parameters are recursively updated in real-time based on the newly available actual load and weather data. The time series functions are represented by Fourier series, and the important harmonic components are identified by off-line spectrum analysis. The nonlinear load-weather functions are modeled using cubic functions, and the residual load function is represented by an ARMA (Autoregressive Moving Average) model. In order to improve the forecasting accuracy and reliability under certain abnormal conditions, such as severe cold fronts in winter or heat wave in summer, a similar-day load model is also incorporated in the implementation. The similar-day model is developed by conceptually defining a set of similarity functions based on the seasons, day types, and weather conditions. A software package, STLF, has been developed based on the proposed models. It has demonstrated successful operation in several power utilities. Off-line testing and on-line operation has consistently shown satisfactory performance.

  12. High nitrogen removal rate using ANAMMOX process at short hydraulic retention time.

    PubMed

    Casagrande, C G; Kunz, A; De Prá, M C; Bressan, C R; Soares, H M

    2013-01-01

    The anaerobic ammonium oxidation (ANAMMOX) is a chemolithoautotrophic process, which converts NH(4)(+) to N(2) using nitrite (NO(2)(-)) as the electron acceptor. This process has very high nitrogen removal rates (NRRs) and is an alternative to classical nitrification/denitrification wastewater treatment. In the present work, a strategy for nitrogen removal using ANAMMOX process was tested evaluating their performance when submitted to high loading rates and very short hydraulic retention times (HRTs). An up-flow ANAMMOX column reactor was inoculated with 30% biomass (v v(-1)) fed from 100 to 200 mg L(-1) of total N (NO(2)(-)-N + NH(4)(+)-N) at 35 °C. After start-up and process stability the maximum NRR in the up-flow anaerobic sludge blanket (UASB) reactor was 18.3 g-N L(-1) d(-1) operated at 0.2 h of HRT. FISH (fluorescence in situ hybridization) analysis and process stoichiometry confirmed that ANAMMOX was the prevalent process for nitrogen removal during the experiments. The results point out that high NRRs can be obtained at very short HRTs using up-flow ANAMMOX column reactor configuration. PMID:23416586

  13. Qualitative Features Extraction from Sensor Data using Short-time Fourier Transform

    NASA Technical Reports Server (NTRS)

    Amini, Abolfazl M.; Figueroa, Fernando

    2004-01-01

    The information gathered from sensors is used to determine the health of a sensor. Once a normal mode of operation is established any deviation from the normal behavior indicates a change. This change may be due to a malfunction of the sensor(s) or the system (or process). The step-up and step-down features, as well as sensor disturbances are assumed to be exponential. An RC network is used to model the main process, which is defined by a step-up (charging), drift, and step-down (discharging). The sensor disturbances and spike are added while the system is in drift. The system runs for a period of at least three time-constants of the main process every time a process feature occurs (e.g. step change). The Short-Time Fourier Transform of the Signal is taken using the Hamming window. Three window widths are used. The DC value is removed from the windowed data prior to taking the FFT. The resulting three dimensional spectral plots provide good time frequency resolution. The results indicate distinct shapes corresponding to each process.

  14. Fluctuation of similarity to detect transitions between distinct dynamical regimes in short time series

    NASA Astrophysics Data System (ADS)

    Malik, Nishant; Marwan, Norbert; Zou, Yong; Mucha, Peter J.; Kurths, Jürgen

    2014-06-01

    A method to identify distinct dynamical regimes and transitions between those regimes in a short univariate time series was recently introduced [N. Malik et al., Europhys. Lett. 97, 40009 (2012), 10.1209/0295-5075/97/40009], employing the computation of fluctuations in a measure of nonlinear similarity based on local recurrence properties. In this work, we describe the details of the analytical relationships between this newly introduced measure and the well-known concepts of attractor dimensions and Lyapunov exponents. We show that the new measure has linear dependence on the effective dimension of the attractor and it measures the variations in the sum of the Lyapunov spectrum. To illustrate the practical usefulness of the method, we identify various types of dynamical transitions in different nonlinear models. We present testbed examples for the new method's robustness against noise and missing values in the time series. We also use this method to analyze time series of social dynamics, specifically an analysis of the US crime record time series from 1975 to 1993. Using this method, we find that dynamical complexity in robberies was influenced by the unemployment rate until the late 1980s. We have also observed a dynamical transition in homicide and robbery rates in the late 1980s and early 1990s, leading to increase in the dynamical complexity of these rates.

  15. Gene expression profiling of canine osteosarcoma reveals genes associated with short and long survival times

    PubMed Central

    Selvarajah, Gayathri T; Kirpensteijn, Jolle; van Wolferen, Monique E; Rao, Nagesha AS; Fieten, Hille; Mol, Jan A

    2009-01-01

    Background Gene expression profiling of spontaneous tumors in the dog offers a unique translational opportunity to identify prognostic biomarkers and signaling pathways that are common to both canine and human. Osteosarcoma (OS) accounts for approximately 80% of all malignant bone tumors in the dog. Canine OS are highly comparable with their human counterpart with respect to histology, high metastatic rate and poor long-term survival. This study investigates the prognostic gene profile among thirty-two primary canine OS using canine specific cDNA microarrays representing 20,313 genes to identify genes and cellular signaling pathways associated with survival. This, the first report of its kind in dogs with OS, also demonstrates the advantages of cross-species comparison with human OS. Results The 32 tumors were classified into two prognostic groups based on survival time (ST). They were defined as short survivors (dogs with poor prognosis: surviving fewer than 6 months) and long survivors (dogs with better prognosis: surviving 6 months or longer). Fifty-one transcripts were found to be differentially expressed, with common upregulation of these genes in the short survivors. The overexpressed genes in short survivors are associated with possible roles in proliferation, drug resistance or metastasis. Several deregulated pathways identified in the present study, including Wnt signaling, Integrin signaling and Chemokine/cytokine signaling are comparable to the pathway analysis conducted on human OS gene profiles, emphasizing the value of the dog as an excellent model for humans. Conclusion A molecular-based method for discrimination of outcome for short and long survivors is useful for future prognostic stratification at initial diagnosis, where genes and pathways associated with cell cycle/proliferation, drug resistance and metastasis could be potential targets for diagnosis and therapy. The similarities between human and canine OS makes the dog a suitable pre-clinical model for future 'novel' therapeutic approaches where the current research has provided new insights on prognostic genes, molecular pathways and mechanisms involved in OS pathogenesis and disease progression. PMID:19735553

  16. Evidence for two distinct morphological classes of gamma-ray bursts from their short time scale variability

    NASA Technical Reports Server (NTRS)

    Lamb, D. Q.; Graziani, C.; Smith, I. A.

    1993-01-01

    We have analyzed the 241 bursts for which peak counts (C)max exist in the publicly available Burst and Transient Source Experiment (BATSE) catalog. Introducing peak counts in 1024 ms as a measure of burst brightness B and the ratio of peak counts in 64 and 1024 ms as a measure of short timescale variability V, we find a statistically significant correlation between the brightness and the short time scale variability of gamma-ray bursts. The bursts which are smoother on short time scales are both faint and bright, while the bursts which are variable on short time scales are faint only, suggesting the existence of two distinct morphological classes of bursts.

  17. Instantaneous Heart Rate detection using short-time autocorrelation for wearable healthcare systems.

    PubMed

    Nakano, Masanao; Konishi, Toshihiro; Izumi, Shintaro; Kawaguchi, Hiroshi; Yoshimoto, Masahiko

    2012-01-01

    This report describes a robust method of Instantaneous Heart Rate (IHR) detection from noisy electrocardiogram (ECG) signals. Generally, the IHR is calculated from the interval of R-waves. Then, the R-waves are extracted from the ECG using a threshold. However, in wearable biosignal monitoring systems, various noises (e.g. muscle artifacts from myoelectric signals, electrode motion artifacts) increase incidences of misdetection and false detection because the power consumption and electrode distance of the wearable sensor are limited to reduce its size and weight. To prevent incorrect detection, we use a short-time autocorrelation technique. The proposed method uses similarity of the waveform of the QRS complex. Therefore, it has no threshold calculation Process and it is robust for noisy environment. Simulation results show that the proposed method improves the success rate of IHR detection by up to 37%. PMID:23367467

  18. Transient polar motions and the nature of the asthenosphere for short time scales

    NASA Technical Reports Server (NTRS)

    Boschi, E.; Sabadini, R.; Yuen, D. A.

    1985-01-01

    A uniformly valid mathematical formalism is developed to study the secular motions of the rotational axis of a layered viscoelastic earth due to seismic excitation. The changes required for implementing the formulation within the framework of the faulting problem. The rationale of adopting the chosen nrheological model, which contains a low-viscosity zone beneath the lithosphere and is based on linear Maxell constitutive relationship, is discussed. The impact of this low-viscosity channel on thhe two families of relaxation time, governing both isostatic readjustment and rotational processes, is considered. It is found that the polar motions depend sensitively on the viscosity structure of the asthenosphere and not at all on the underlying mantle. A gloal low-velocity zone with short-term asthenospheric viscosities less than about 5 x 10 to the 18th Pa-s and widths greater than 50 km is ruled out.

  19. Super-resolution spectral estimation in short-time non-contact vital sign measurement

    NASA Astrophysics Data System (ADS)

    Sun, Li; Li, Yusheng; Hong, Hong; Xi, Feng; Cai, Weidong; Zhu, Xiaohua

    2015-04-01

    Non-contact techniques for measuring vital signs attract great interest due to the benefits shown in medical monitoring, military application, etc. However, the presence of respiration harmonics caused by nonlinear phase modulation will result in performance degradation. Suffering from smearing and leakage problems, conventional discrete Fourier transform (DFT) based methods cannot distinguish the heartbeat component from closely located respiration harmonics in frequency domain, especially in short-time processing. In this paper, the theory of sparse reconstruction is merged with an extended harmonic model of vital signals, aiming at achieving a super-resolution spectral estimation of vital signals by additionally exploiting the inherent sparse prior information. Both simulated and experimental results show that the proposed algorithm has superior performance to DFT-based methods and the recently applied multiple signal classification algorithm, and the required processing window length has been shortened to 5.12 s.

  20. The Phase Derivative Around Zeros of the Short-Time Fourier Transform

    E-print Network

    Balazs, Peter; Jaillet, Florent; Søndergaard, Peter

    2011-01-01

    The phase of the short-time Fourier transform (STFT) is sometimes considered difficult to interpret. However, the phase information is important for improved analysis and processing. The phase derivative, in particular, is essential for the reassignment method or the phase vocoder algorithm. In order to understand the phase derivative of the STFT more thoroughly, we describe an interesting phenomenon, a recurring pattern in the neighborhood of zeros. Contrary to the possible expectation of an arbitrary behavior, the phase derivative always shows a singularity with the same characteristic shape with a negative and a positive peak of infinite height at these points. We show this behavior in a numerical investigation, present a simple explicit analytic example and then do a complete analytical treatment. For this we present several intermediate results about the regularity of the STFT for Schwartz windows, which are of independent interest.

  1. Arbitrary phase shift of a semiconductor quantum dot charge qubit on a short time scale

    NASA Astrophysics Data System (ADS)

    Cao, Gang; Li, Hai-Ou; Song, Xiang-Xiang; Yu, Guo-Dong; Chen, Bao-Bao; Xiao, Ming; Guo, Guo-Ping

    2015-11-01

    We present an experimental technique to better control the phase of an electron charge qubit, formed by a GaAs double quantum dot. A standard non-adiabatic gate pulse is used to generate the qubit rotation around the x-axis of the Bloch sphere. To gain good control of the z-rotation (the phase) on a short time scale, a fast 130 ps tipping pulse is superimposed on the non-adiabatic pulse. The two-axis gate operation is exhibited in the composite pulse excited qubit evolution spectrum. We demonstrate that the dynamic phase can be varied continuously from 0 to 6? by varying the amplitude of the tipping pulse. The understanding of the spectrum is validated through simulation of the von Neumann equation.

  2. Diagnosis of brain tumors using dynamic contrast-enhanced perfusion imaging with a short acquisition time.

    PubMed

    Abe, Takashi; Mizobuchi, Yoshifumi; Nakajima, Kohei; Otomi, Yoichi; Irahara, Saho; Obama, Yuki; Majigsuren, Mungunkhuyag; Khashbat, Delgerdalai; Kageji, Teruyoshi; Nagahiro, Shinji; Harada, Masafumi

    2015-01-01

    This study sought to determine the diagnostic utility of perfusion parameters derived from dynamic contrast-enhanced (DCE) perfusion MRI with a short acquisition time (approximately 3.5 min) in patients with glioma, brain metastasis, and primary CNS lymphoma (PCNSL). Twenty-six patients with 29 lesions (4 low-grade glioma, 13 high-grade glioma, 7 metastasis, and 5 PCNSL) underwent DCE-MRI in a 3 T scanner. A ROI was placed on the hotspot of each tumor in maps for volume transfer contrast K (trans) , extravascular extracellular volume V e , and fractional plasma volume V p . We analyzed differences in parameters between tumors using the Mann-Whitney U test. We calculated sensitivity and specificity using receiver operating characteristics analysis. Mean K (trans) values of LGG, HGG, metastasis and PCNSL were 0.034, 0.31, 0.38, 0.44, respectively. Mean Ve values of each tumors was 0.036, 0.57, 0.47, 0.96, and mean Vp value of each tumors was 0.070, 0.086, 0.26, 0.17, respectively. Compared with other tumor types, low-grade glioma showed lower K (trans) (P?short acquisition time provide useful information for the differential diagnosis of brain tumors. PMID:25793147

  3. Time estimation among low-functioning individuals with autism spectrum disorders: evidence of poor sensitivity to variability of short durations.

    PubMed

    Brodeur, Darlene A; Gordon Green, Cathryn; Flores, Heidi; Burack, Jacob A

    2014-04-01

    Time estimation of short durations (under 1 sec) was examined in low-functioning individuals with autism spectrum disorder (ASD) and typically developing (TD) children matched on mental age. Temporal bisection and generalization tasks were used to examine basic perceptual timing mechanisms. For both tasks, the participants with ASD demonstrated less sensitivity to variability in short durations than the TD children, adding to a growing body of literature suggesting deficits in timing exist for longer durations. The results highlight the need to examine multiple levels of processing of time-related information from basic perceptual mechanisms to higher level cognitive mechanisms. PMID:24574256

  4. Short time scale variability at gamma rays in FSRQs and implications on the current models

    E-print Network

    Foschini, L; Tavecchio, F; Bonnoli, G; Stamerra, A

    2011-01-01

    We studied the rapid variability at GeV gamma rays of the flat-spectrum radio quasar PKS 1222+216, which was recently found by the MAGIC Cerenkov telescope to display very short variability (minutes time scale) at hundreds of GeV. We analyzed the time period between 2010 April 29 and June 20, when the source generated a few gamma-ray flares with flux in the MeV-GeV band in excess of 10^-5 ph cm^-2 s^-1 on daily basis. We set tight upper limits on the observed doubling time scale (0.8 hours on 2010 April 30), the smallest measured to date at MeV-GeV energies, which can constrain the size of the gamma-ray emitting region. We also studied the spectra measured during two flares (2010 April 30 and June 17-18). The combination of spectral and variability studies obtained in the present work favors the hypothesis that gamma rays are generally produced inside the broad-line region (BLR), but sometimes the dissipation can occur at larger distances, nearby the infrared torus.

  5. Quantification of Shear-Induced Platelet Activation: High Shear Stresses for Short Exposure Time.

    PubMed

    Ding, Jun; Chen, Zengsheng; Niu, Shuqiong; Zhang, Jiafeng; Mondal, Nandan K; Griffith, Bartley P; Wu, Zhongjun J

    2015-07-01

    Thrombosis and thromboembolism are the life-threatening clinical complications for patients supported or treated with prosthetic cardiovascular devices. The high mechanical shear stress within these devices is believed to be the major contributing factor to cause platelet activation (PA) and function alteration, leading to thrombotic events. There have been limited quantitative data on how the high mechanical shear stress causes platelet activation. In this study, shear-induced PA in the ranges of well-defined shear stress and exposure time relevant to cardiovascular devices was quantitatively characterized for human blood using two novel flow-through Couette-type blood shearing devices. Four markers of platelet activation-surface P-selectin (CD62p), platelet-derived microparticles (PMPs), platelet-monocyte aggregation (PMA), and soluble P-selectin-were measured by flow cytometry and enzyme-linked immunosorbent assay (ELISA), respectively. The results indicated that PA induced by high shear stresses with short exposure time could be reliably detected with surface P-selectin, and, to a lesser extent, PMPs rather than soluble P-selectin. It was also verified that PMA can be a highly sensitive indirect marker of platelet activation. The quantitative relationship between percentage of activated platelets indicated by surface P-selectin expression and shear stress/exposure time follows well the power law functional form. The coefficients of the power law models of PA based on surface P-selectin expression were derived. PMID:25808300

  6. Short-time dynamics of 2-thiouracil in the light absorbing S2(???) state

    NASA Astrophysics Data System (ADS)

    Jiang, Jie; Zhang, Teng-shuo; Xue, Jia-dan; Zheng, Xuming; Cui, Ganglong; Fang, Wei-hai

    2015-11-01

    Ultrahigh quantum yields of intersystem crossing to the lowest triplet state T1 are observed for 2-thiouracils (2TU), which is in contrast to the natural uracils that predominantly exhibit ultrafast internal conversion to the ground state upon excitation to the singlet excited state. The intersystem crossing mechanism of 2TU has recently been investigated using second-order perturbation methods with a high-level complete-active space self-consistent field. Three competitive nonadiabatic pathways to the lowest triplet state T1 from the initially populated singlet excited state S2 were proposed. We investigate the initial decay dynamics of 2TU from the light absorbing excited states using resonance Raman spectroscopy, time-dependent wave-packet theory in the simple model, and complete-active space self-consistent field (CASSCF) and time dependent-Becke's three-parameter exchange and correlation functional with the Lee-Yang-Parr correlation functional (TD-B3LYP) calculations. The obtained short-time structural dynamics in easy-to-visualize internal coordinates were compared with the CASSCF(16,11) predicted key nonadiabatic decay routes. Our results indicate that the predominant decay pathway initiated at the Franck-Condon region is toward the S2/S1 conical intersection point and S2T3 intersystem crossing point, but not toward the S2T2 intersystem crossing point.

  7. Short Dissipation Times of Proto-planetary Disks: An Artifact of Selection Effects?

    NASA Astrophysics Data System (ADS)

    Pfalzner, Susanne; Steinhausen, Manuel; Menten, Karl

    2014-10-01

    The frequency of disks around young stars, a key parameter for understanding planet formation, is most readily determined in young stellar clusters where many relatively coeval stars are located in close proximity. Observational studies seem to show that the disk frequency decreases rapidly with cluster age with <10% of cluster stars retaining their disks for longer than 2-6 Myr. Given that at least half of all stars in the field seem to harbor one or more planets, this would imply extremely fast disk dispersal and rapid planet growth. Here we question the validity of this constraint by demonstrating that the short disk dissipation times inferred to date might have been heavily underestimated by selection effects. Critically, for ages >3 Myr only stars that originally populated the densest areas of very populous clusters, which are prone to disk erosion, are actually considered. This tiny sample may not be representative of the majority of stars. In fact, the higher disk fractions in co-moving groups indicate that it is likely that over 30% of all field stars retain their disks well beyond 10 Myr, leaving ample time for planet growth. Equally, our solar system, with a likely formation time >10 Myr, need no longer be an exception but in fact typical of planetary systems.

  8. SHORT DISSIPATION TIMES OF PROTO-PLANETARY DISKS: AN ARTIFACT OF SELECTION EFFECTS?

    SciTech Connect

    Pfalzner, Susanne; Steinhausen, Manuel; Menten, Karl

    2014-10-01

    The frequency of disks around young stars, a key parameter for understanding planet formation, is most readily determined in young stellar clusters where many relatively coeval stars are located in close proximity. Observational studies seem to show that the disk frequency decreases rapidly with cluster age with <10% of cluster stars retaining their disks for longer than 2-6 Myr. Given that at least half of all stars in the field seem to harbor one or more planets, this would imply extremely fast disk dispersal and rapid planet growth. Here we question the validity of this constraint by demonstrating that the short disk dissipation times inferred to date might have been heavily underestimated by selection effects. Critically, for ages >3 Myr only stars that originally populated the densest areas of very populous clusters, which are prone to disk erosion, are actually considered. This tiny sample may not be representative of the majority of stars. In fact, the higher disk fractions in co-moving groups indicate that it is likely that over 30% of all field stars retain their disks well beyond 10 Myr, leaving ample time for planet growth. Equally, our solar system, with a likely formation time >10 Myr, need no longer be an exception but in fact typical of planetary systems.

  9. Multi-time-scale heat transfer modeling of turbid tissues exposed to short-pulsed irradiations.

    PubMed

    Kim, Kyunghan; Guo, Zhixiong

    2007-05-01

    A combined hyperbolic radiation and conduction heat transfer model is developed to simulate multi-time-scale heat transfer in turbid tissues exposed to short-pulsed irradiations. An initial temperature response of a tissue to an ultrashort pulse irradiation is analyzed by the volume-average method in combination with the transient discrete ordinates method for modeling the ultrafast radiation heat transfer. This response is found to reach pseudo steady state within 1 ns for the considered tissues. The single pulse result is then utilized to obtain the temperature response to pulse train irradiation at the microsecond/millisecond time scales. After that, the temperature field is predicted by the hyperbolic heat conduction model which is solved by the MacCormack's scheme with error terms correction. Finally, the hyperbolic conduction is compared with the traditional parabolic heat diffusion model. It is found that the maximum local temperatures are larger in the hyperbolic prediction than the parabolic prediction. In the modeled dermis tissue, a 7% non-dimensional temperature increase is found. After about 10 thermal relaxation times, thermal waves fade away and the predictions between the hyperbolic and parabolic models are consistent. PMID:17335934

  10. Short-time dynamics of 2-thiouracil in the light absorbing S2(??(?)) state.

    PubMed

    Jiang, Jie; Zhang, Teng-Shuo; Xue, Jia-Dan; Zheng, Xuming; Cui, Ganglong; Fang, Wei-Hai

    2015-11-01

    Ultrahigh quantum yields of intersystem crossing to the lowest triplet state T1 are observed for 2-thiouracils (2TU), which is in contrast to the natural uracils that predominantly exhibit ultrafast internal conversion to the ground state upon excitation to the singlet excited state. The intersystem crossing mechanism of 2TU has recently been investigated using second-order perturbation methods with a high-level complete-active space self-consistent field. Three competitive nonadiabatic pathways to the lowest triplet state T1 from the initially populated singlet excited state S2 were proposed. We investigate the initial decay dynamics of 2TU from the light absorbing excited states using resonance Raman spectroscopy, time-dependent wave-packet theory in the simple model, and complete-active space self-consistent field (CASSCF) and time dependent-Becke's three-parameter exchange and correlation functional with the Lee-Yang-Parr correlation functional (TD-B3LYP) calculations. The obtained short-time structural dynamics in easy-to-visualize internal coordinates were compared with the CASSCF(16,11) predicted key nonadiabatic decay routes. Our results indicate that the predominant decay pathway initiated at the Franck-Condon region is toward the S2/S1 conical intersection point and S2T3 intersystem crossing point, but not toward the S2T2 intersystem crossing point. PMID:26547183

  11. Local routes revisited: the space and time dependence of the Ca2+ signal for phasic transmitter release at the rat calyx of Held

    PubMed Central

    Meinrenken, Christoph J; Borst, J Gerard G; Sakmann, Bert

    2003-01-01

    During the last decade, advances in experimental techniques and quantitative modelling have resulted in the development of the calyx of Held as one of the best preparations in which to study synaptic transmission. Here we review some of these advances, including simultaneous recording of pre- and postsynaptic currents, measuring the Ca2+ sensitivity of transmitter release, reconstructing the 3-D anatomy at the electron microscope (EM) level, and modelling the buffered diffusion of Ca2+ in the nerve terminal. An important outcome of these studies is an improved understanding of the Ca2+ signal that controls phasic transmitter release. This article illustrates the spatial and temporal aspects of the three main steps in the presynaptic signalling cascade: Ca2+ influx through voltage-gated calcium channels, buffered Ca2+ diffusion from the channels to releasable vesicles, and activation of the Ca2+ sensor for release. Particular emphasis is placed on how presynaptic Ca2+ buffers affect the Ca2+ signal and thus the amplitude and time course of the release probability. Since many aspects of the signalling cascade were first conceived with reference to the squid giant presynaptic terminal, we include comparisons with the squid model and revisit some of its implications. Whilst the characteristics of buffered Ca2+ diffusion presented here are based on the calyx of Held, we demonstrate the circumstances under which they may be valid for other nerve terminals at mammalian CNS synapses. PMID:12562955

  12. Short Gamma-Ray Bursts in the "Time-reversal" Scenario

    NASA Astrophysics Data System (ADS)

    Ciolfi, Riccardo; Siegel, Daniel M.

    2015-01-01

    Short gamma-ray bursts (SGRBs) are among the most luminous explosions in the universe and their origin still remains uncertain. Observational evidence favors the association with binary neutron star or neutron star-black hole (NS-BH) binary mergers. Leading models relate SGRBs to a relativistic jet launched by the BH-torus system resulting from the merger. However, recent observations have revealed a large fraction of SGRB events accompanied by X-ray afterglows with durations ~102-105 s, suggesting continuous energy injection from a long-lived central engine, which is incompatible with the short (lsim 1 s) accretion timescale of a BH-torus system. The formation of a supramassive NS, resisting the collapse on much longer spin-down timescales, can explain these afterglow durations, but leaves serious doubts on whether a relativistic jet can be launched at the merger. Here we present a novel scenario accommodating both aspects, where the SGRB is produced after the collapse of a supramassive NS. Early differential rotation and subsequent spin-down emission generate an optically thick environment around the NS consisting of a photon-pair nebula and an outer shell of baryon-loaded ejecta. While the jet easily drills through this environment, spin-down radiation diffuses outward on much longer timescales and accumulates a delay that allows the SGRB to be observed before (part of) the long-lasting X-ray signal. By analyzing diffusion timescales for a wide range of physical parameters, we find delays that can generally reach ~105 s, compatible with observations. The success of this fundamental test makes this "time-reversal" scenario an attractive alternative to current SGRB models.

  13. SHORT GAMMA-RAY BURSTS IN THE ''TIME-REVERSAL'' SCENARIO

    SciTech Connect

    Ciolfi, Riccardo; Siegel, Daniel M. E-mail: daniel.siegel@aei.mpg.de

    2015-01-10

    Short gamma-ray bursts (SGRBs) are among the most luminous explosions in the universe and their origin still remains uncertain. Observational evidence favors the association with binary neutron star or neutron star-black hole (NS-BH) binary mergers. Leading models relate SGRBs to a relativistic jet launched by the BH-torus system resulting from the merger. However, recent observations have revealed a large fraction of SGRB events accompanied by X-ray afterglows with durations ?10{sup 2}-10{sup 5} s, suggesting continuous energy injection from a long-lived central engine, which is incompatible with the short (? 1 s) accretion timescale of a BH-torus system. The formation of a supramassive NS, resisting the collapse on much longer spin-down timescales, can explain these afterglow durations, but leaves serious doubts on whether a relativistic jet can be launched at the merger. Here we present a novel scenario accommodating both aspects, where the SGRB is produced after the collapse of a supramassive NS. Early differential rotation and subsequent spin-down emission generate an optically thick environment around the NS consisting of a photon-pair nebula and an outer shell of baryon-loaded ejecta. While the jet easily drills through this environment, spin-down radiation diffuses outward on much longer timescales and accumulates a delay that allows the SGRB to be observed before (part of) the long-lasting X-ray signal. By analyzing diffusion timescales for a wide range of physical parameters, we find delays that can generally reach ?10{sup 5} s, compatible with observations. The success of this fundamental test makes this ''time-reversal'' scenario an attractive alternative to current SGRB models.

  14. Short gamma-ray bursts in the "time-reversal" scenario

    E-print Network

    Riccardo Ciolfi; Daniel M. Siegel

    2015-01-27

    Short gamma-ray bursts (SGRBs) are among the most luminous explosions in the Universe and their origin still remains uncertain. Observational evidence favors the association with binary neutron star or neutron star-black hole (NS-BH) binary mergers. Leading models relate SGRBs to a relativistic jet launched by the BH-torus system resulting from the merger. However, recent observations have revealed a large fraction of SGRB events accompanied by X-ray afterglows with durations $\\sim10^2\\!-\\!10^5~\\mathrm{s}$, suggesting continuous energy injection from a long-lived central engine, which is incompatible with the short ($\\lesssim1~\\mathrm{s}$) accretion timescale of a BH-torus system. The formation of a supramassive NS, resisting the collapse on much longer spin-down timescales, can explain these afterglow durations, but leaves serious doubts on whether a relativistic jet can be launched at merger. Here we present a novel scenario accommodating both aspects, where the SGRB is produced after the collapse of a supramassive NS. Early differential rotation and subsequent spin-down emission generate an optically thick environment around the NS consisting of a photon-pair nebula and an outer shell of baryon-loaded ejecta. While the jet easily drills through this environment, spin-down radiation diffuses outwards on much longer timescales and accumulates a delay that allows the SGRB to be observed before (part of) the long-lasting X-ray signal. By analyzing diffusion timescales for a wide range of physical parameters, we find delays that can generally reach $\\sim10^5~\\mathrm{s}$, compatible with observations. The success of this fundamental test makes this "time-reversal" scenario an attractive alternative to current SGRB models.

  15. Short-time hydrothermal synthesis and delamination of ion exchangeable Mg/Ga layered double hydroxides

    SciTech Connect

    Unal, Ugur

    2007-09-15

    The hydrothermal synthesis of magnesium-gallium layered double hydroxides (Mg/Ga LDHs) was studied under static and agitated conditions. Not only well-crystallized and large-sized Mg/Ga LDHs having hexagonal morphology were obtained but also the reaction time was comparatively decreased from 24 to 2 h by means of agitation during hydrothermal synthesis. In static conditions, mainly GaOOH and magnesite phases were formed. The elemental analysis results show that the final Mg/Ga ratio is significantly different from the initial ratio. The reason was attributed to the difference in the hydrolytic behavior of Mg{sup 2+} and Ga{sup 3+}. Furthermore, the anion exchange studies with glycine, dodecyl sulfate, ferrocyanide and ferricyanide were performed to investigate the intercalation behavior of the anions into Mg/Ga LDHs. In addition, delamination of Mg/Ga LDHs was performed in formamide for the glycine exchanged forms. Large size of nanosheets thus obtained can be utilized in the fabrication of functional thin films. - Graphical abstract: Hydrothermal synthesis under agitation resulted in highly crystalline Mg/Ga LDHs slabs in a short time. The LDHs slabs were delaminated into two-dimensional nanosize sheets.

  16. Temperature measurement by IR camera of heated device to high temperature during a short time

    NASA Astrophysics Data System (ADS)

    Sonneck-Museux, Nathanaëlle; Vergé, Philippe; Judic, Jean-Pierre; Edard, Pierrick

    2015-04-01

    A device allowing heating a liquid to high temperatures during a very short time has been conceived in our laboratory. The goal of this survey is to find the suitable experimental configurations, so that tested material affected by the temperatures coved between 200 and 750°C. This study is achieved to the Solar Furnace of the DGA in Odeillo. The cavity containing the liquid is a thermocouple sleeve (capillary) in Inconel 600. Its extremity is closed tightly by a removable steel plug permitting the tightness after replenishment. An electromagnet associated to a generator of delay permit to make fall the whole after the solar irradiation in liquid nitrogen in order to stop the reaction of "deterioration" of the tested product. According to capillary dimensions and to heating time, the temperature measurement using a pyrometer is not possible. A second possibility is using thermocouple, but it is not easy to join this captor on Inconel 600. Using by infrared camera allows observing the presence or the absence of inflammation during the solar irradiation and the sleeve fall too. The measures of temperatures by thermocouple show a lot of variability. The measures comparison with those by infrared camera shows a phenomenon of "heat well". Several score of tests to the solar furnace have been achieved in different experimental configurations. Nine experimental configurations have been validated, for variable flux of 100 to 500W/cm². The observation by infrared camera permitted to validate the conceived system and to verify the homogeneity of the sleeve heated.

  17. "Sony Revisited," Revisited Another look at the paper that presaged

    E-print Network

    Hollaar, Lee A.

    "Sony Revisited," Revisited Another look at the paper that presaged Grokster and inducement of this paper is available at http://digital-law-online.info/papers/lah/sony-revisited.htm August 10, 2005 Draft Foreword In April 2004, I finished the first draft of the paper "Sony Revisited: A new look at contributory

  18. Time-Based Loss in Visual Short-Term Memory Is from Trace Decay, Not Temporal Distinctiveness

    ERIC Educational Resources Information Center

    Ricker, Timothy J.; Spiegel, Lauren R.; Cowan, Nelson

    2014-01-01

    There is no consensus as to why forgetting occurs in short-term memory tasks. In past work, we have shown that forgetting occurs with the passage of time, but there are 2 classes of theories that can explain this effect. In the present work, we investigate the reason for time-based forgetting by contrasting the predictions of temporal…

  19. Comparison of the short-time Fourier transform and wavelet transform for analysis of transient signal events 

    E-print Network

    Pilgrim, Richard Allen

    1994-01-01

    The performance characteristics of the wavelet transform and the short-time Fourier transform (STFT) for transient detection are examined by means of computer simulation. The STFT uses a power-of-two decimation-in-time FFT with various frame sizes...

  20. Received 21 Dec 2012 | Accepted 9 May 2013 | Published 14 Jun 2013 Short-time movement of E. coli chromosomal

    E-print Network

    Cicuta, Pietro

    ARTICLE Received 21 Dec 2012 | Accepted 9 May 2013 | Published 14 Jun 2013 Short-time movement of E. coli chromosomal loci depends on coordinate and subcellular localization Avelino Javer1,*, Zhicheng in Escherichia coli at different growth rates. At these timescales, we observe for the first time a dependence

  1. Security of Blind Signatures Revisited Dominique Schroder 1 and Dominique Unruh2

    E-print Network

    International Association for Cryptologic Research (IACR)

    Security of Blind Signatures Revisited Dominique Schr¨oder 1 and Dominique Unruh2 1 University of Maryland, USA 2 University of Tartu, Estonia Abstract. We revisit the definition of unforgeability of blind that this established definition falls short in two ways of what one would intuitively expect from a secure blind

  2. Short- and Long-Term Statistical Properties of Heartbeat Time-Series in Healthy and Pathological Subjects

    E-print Network

    Paolo Allegrini; Rita Balocchi; Santi Chillemi; Paolo Grigolini; Luigi Palatella; Giacomo Raffaelli

    2002-09-02

    We analize heartbeat time-series corresponding to several groups of individuals (healthy, heart transplanted, with congestive heart failure (CHF), after myocardial infarction (MI), hypertensive), looking for short- and long-time statistical behaviors. In particular we study the persistency patterns of interbeat times and interbeat-time variations. Long-range correlations are revealed using an information-based technique which makes a wise use of the available statistics. The presence of strong long-range time correlations seems to be a general feature for all subjects, with the exception of some CHF individuals. We also show that short time-properties detected in healthy subjects, and seen also in hypertensive and MI patients, and completely absent in the trasplanted, are characterized by a general behavior when we apply a proper coarse-graining procedure for time series analysis.

  3. Suborbital Intercept and Fragmentation of an Asteroid with Very Short Warning Time Scenario

    NASA Technical Reports Server (NTRS)

    Hupp, Ryan; DeWald, Spencer; Wie, Bong; Barbee, Brent W.

    2015-01-01

    Small near-Earth objects (NEOs) is approx. 50-150 m in size are far more numerous (hundreds of thousands to millions yet to be discovered) than larger NEOs. Small NEOs, which are mostly asteroids rather than comets, are very faint in the night sky due to their small sizes, and are, therefore, difficult to discover far in advance of Earth impact. Furthermore, even small NEOs are capable of creating explosions with energies on the order of tens or hundreds of megatons (Mt). We are, therefore, motivated to prepare to respond effectively to short warning time, small NEO impact scenarios. In this paper we explore the lower bound on actionable warning time by investigating the performance of notional upgraded Intercontinental Ballistic Missiles (ICBMs) to carry Nuclear Explosive Device (NED) payloads to intercept and disrupt a hypothetical incoming NEO at high altitudes (generally at least 2500 km above Earth). We conduct this investigation by developing optimal NEO intercept trajectories for a range of cases and comparing their performances. Our results show that suborbital NEO intercepts using Minuteman III or SM-3 IIA launch vehicles could achieve NEO intercept a few minutes prior to when the NEO would strike Earth. We also find that more powerful versions of the launch vehicles (e.g., total deltaV is approx. 9.5-11 km/s) could intercept incoming NEOs several hours prior to when the NEO would strike Earth, if launched at least several days prior to the time of intercept. Finally, we discuss a number of limiting factors and practicalities that affect whether the notional systems we describe could become feasible.

  4. Suborbital Asteroid Intercept and Fragmentation for Very Short Warning Time Scenarios

    NASA Technical Reports Server (NTRS)

    Hupp, Ryan; Dewald, Spencer; Wie, Bong; Barbee, Brent W.

    2015-01-01

    Small near-Earth objects (NEOs) 50150 m in size are far more numerous (hundreds of thousands to millions yet to be discovered) than larger NEOs. Small NEOs, which are mostly asteroids rather than comets, are very faint in the night sky due to their small sizes, and are, therefore, difficult to discover far in advance of Earth impact. However, even small NEOs are capable of creating explosions with energies on the order of tens or hundreds of megatons (Mt).We are, therefore, motivated to prepare to respond effectively to short warning time, small NEO impact scenarios. In this paper we explore the lower bound on actionable warning time by investigating the performance of notional upgraded Intercontinental Ballistic Missiles (ICBMs) to carry Nuclear Explosive Device (NED) payloads to intercept and disrupt a fictitious incoming NEO at high altitudes (generally, at least 2500 km above Earth). We conduct this investigation by developing optimal NEO intercept trajectories for a range of cases and comparing their performances.Our results show that suborbital NEO intercepts using Minuteman III or SM-3 IIA launch vehicles could achieve NEO intercept a few minutes prior to when the NEOwould strike Earth. We also find that more powerful versions of the launch vehicles (e.g., total V 9.511 kms) could intercept incoming NEOs over a day prior to when the NEO would strike Earth, if launched at least several days prior to the time of NEO intercept. Finally, we discuss a number of limiting factors and practicalities that affect whether the notional systems we describe could become feasible.

  5. A Real-Time MODIS Vegetation Composite for Land Surface Models and Short-Term Forecasting

    NASA Technical Reports Server (NTRS)

    Case, Jonathan L.; LaFontaine, Frank J.; Kumar, Sujay V.; Jedlovec, Gary J.

    2011-01-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center is producing real-time, 1- km resolution Normalized Difference Vegetation Index (NDVI) gridded composites over a Continental U.S. domain. These composites are updated daily based on swath data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor aboard the polar orbiting NASA Aqua and Terra satellites, with a product time lag of about one day. A simple time-weighting algorithm is applied to the NDVI swath data that queries the previous 20 days of data to ensure a continuous grid of data populated at all pixels. The daily composites exhibited good continuity both spatially and temporally during June and July 2010. The composites also nicely depicted high greenness anomalies that resulted from significant rainfall over southwestern Texas, Mexico, and New Mexico during July due to early-season tropical cyclone activity. The SPoRT Center is in the process of computing greenness vegetation fraction (GVF) composites from the MODIS NDVI data at the same spatial and temporal resolution for use in the NASA Land Information System (LIS). The new daily GVF dataset would replace the monthly climatological GVF database (based on Advanced Very High Resolution Radiometer [AVHRR] observations from 1992-93) currently available to the Noah land surface model (LSM) in both LIS and the public version of the Weather Research and Forecasting (WRF) model. The much higher spatial resolution (1 km versus 0.15 degree) and daily updates based on real-time satellite observations have the capability to greatly improve the simulation of the surface energy budget in the Noah LSM within LIS and WRF. Once code is developed in LIS to incorporate the daily updated GVFs, the SPoRT Center will conduct simulation sensitivity experiments to quantify the impacts and improvements realized by the MODIS real-time GVF data. This presentation will describe the methodology used to develop the 1-km MODIS NDVI composites and show sample output from summer 2010, compare the MODIS GVF data to the AVHRR monthly climatology, and illustrate the sensitivity of the Noah LSM within LIS and/or the coupled LIS/WRF system to the new MODIS GVF dataset.

  6. Thermal sterilization of heat-sensitive products using high-temperature short-time sterilization.

    PubMed

    Mann, A; Kiefer, M; Leuenberger, H

    2001-03-01

    High-temperature short-time (HTST) sterilization with a continuous-flow sterilizer, developed for this study, was evaluated. The evaluation was performed with respect to (a) the chemical degradation of two heat-sensitive drugs in HTST range (140-160 degrees C) and (b) the microbiological effect of HTST sterilization. Degradation kinetics of two heat-sensitive drugs showed that a high peak temperature sterilization process resulted in less chemical degradation for the same microbiological effect than a low peak temperature process. Both drugs investigated could be sterilized with acceptable degradation at HTST conditions. For the evaluation of the microbiological effect, Bacillus stearothermophilus ATCC 7953 spores were used as indicator bacteria. Indicator spore kinetics (D(T), z value, k, and E(a)), were determined in the HTST range. A comparison between the Bigelow model (z value concept) and the Arrhenius model, used to describe the temperature coefficient of the microbial inactivation, demonstrated that the Bigelow model is more accurate in prediction of D(T) values in the HTST range. The temperature coefficient decreased with increasing temperature. The influence of Ca(2+) ions and pH value on the heat resistance of the indicator spores, which is known under typical sterilization conditions, did not change under HTST conditions. PMID:11170021

  7. The influence of alcoholic intoxication on the short-time energy function of speech.

    PubMed

    Heinrich, Christian; Schiel, Florian

    2014-05-01

    This study investigates rhythmic features based on the short-time energy function of speech signals with the aim of finding robust, speaker-independent features that indicate speaker intoxication. Data from the German Alcohol Language Corpus, which comprises read, spontaneous, and command&control speech uttered by 162 speakers of both genders and various age groups when sober and intoxicated, were analyzed. Energy contours are compared directly (Root Mean Squared Error, statistical correlation, or the Euclidean distance in the spectral space of the contour) and by parameterization of the contour using the Discrete Cosine Transform (DCT) and the first and second moments of the lower DCT spectrum. Contours are also analyzed by Principal Components Analysis aiming at fundamental "eigen contour" changes that might encode intoxication. Energy contours differ significantly with intoxication in terms of distance measures, the second and fourth DCT coefficients, and the first and second moments of the lower DCT spectrum. Principal Components Analysis did not yield interpretable "eigen contours" that could be used in distinguishing intoxicated from sober contours. PMID:24815274

  8. SHORT CONTACT TIME DIRECT COAL LIQUEFACTION USING A NOVEL BATCH REACTOR

    SciTech Connect

    Michael T. Klein; William H. Calkins

    1997-10-29

    The overall goal of this research is to develop an understanding of the Direct Coal Liquefaction process at the molecular level. Many approaches have been used to study this process including kinetic studies, study of the liquefaction products, study of the effect of reaction variables, such as temperature, solvent type and composition, the changing nature and composition of the coal during liquefaction, and the distribution in the liquefaction products of the hydrogen consumed. While all these studies have contributed to our growing knowledge of the liquefaction process, an adequate understanding of direct liquefaction still eludes us. This is due to many reasons including: the complexity and variable nature of coal itself and the many different chemical reactions which are occurring simultaneously during direct coal liquefaction. We believe that a study of the liquefaction process at the very early stages will avoid the complexities of secondary reactions associated with free radical high temperature processes that are clearly involved in direct coal liquefaction. This prompted us to devise a reactor system which avoids long heat up and cool-down times associated with previous kinetic studies, and allows kinetic measurements even at as short as the first few seconds of the liquefaction reaction.

  9. Histological and cytological examination of rat reproductive tissue after short-time intermittent radiofrequency exposure.

    PubMed

    Troši?, Ivan?ica; Matauši?-Pišl, Mirjana; Pavi?i?, Ivan; Marjanovi?, Ana Marija

    2013-12-01

    The unfavourable outcomes of mobile phone use on male fertility have still not been fully elaborated. To establish the potentially adverse effects of everyday exposure to radiofrequency radiation (RF) on humans, we performed a controlled animal study that aimed to investigate the influence of RF radiation on rat testis histology as well as the amount, mobility, and structure of epididymal free sperm cell population. Eighteen adult male rats were divided into two groups of nine. One group comprised sham-exposed control animals, while the other group endured total body irradiation for an hour daily during two weeks. A 915 MHz RF field, power density of 2.4 W m(-2) and strength of 30 V m(-1) was generated in a Gigahertz Transversal Electromagnetic chamber. The specific absorption rate (SAR) was 0.6 W kg(-1). Body mass and temperature were measured before and after each exposure treatment. Immediately after the last exposure, the animals were sacrificed and testes removed and prepared for histological analysis. The free sperm cells were collected from the cauda epididymis and their quantity, quality, and morphology were microscopically determined using a haemocytometer. No statistically significant alteration in any of the endpoints was observed. This study found no evidence of an unfavourable effect of the applied RF radiation on testicular function or structure. Based on these results, we can conclude that short-time intermittent exposure to RF radiation does not represent a significant risk factor for rat reproductive functions. PMID:24384757

  10. Generalization of Clausius-Mossotti approximation in application to short-time transport properties of suspensions

    NASA Astrophysics Data System (ADS)

    Makuch, Karol

    2015-10-01

    In 1983, Felderhof, Ford, and Cohen gave microscopic explanation of the famous Clausius-Mossotti formula for the dielectric constant of nonpolar dielectric. They based their considerations on the cluster expansion of the dielectric constant, which relates this macroscopic property with the microscopic characteristics of the system. In this article, we analyze the cluster expansion of Felderhof, Ford, and Cohen by performing its resummation (renormalization). Our analysis leads to the ring expansion for the macroscopic characteristic of the system, which is an expression alternative to the cluster expansion. Using similarity of structures of the cluster expansion and the ring expansion, we generalize (renormalize) the Clausius-Mossotti approximation. We apply our renormalized Clausius-Mossotti approximation to the case of the short-time transport properties of suspensions, calculating the effective viscosity and the hydrodynamic function with the translational self-diffusion and the collective diffusion coefficient. We perform calculations for monodisperse hard-sphere suspensions in equilibrium with volume fraction up to 45 % . To assess the renormalized Clausius-Mossotti approximation, it is compared with numerical simulations and the Beenakker-Mazur method. The results of our renormalized Clausius-Mossotti approximation lead to comparable or much less error (with respect to the numerical simulations) than the Beenakker-Mazur method for the volume fractions below ? ?30 % (apart from a small range of wave vectors in hydrodynamic function). For volume fractions above ? ?30 % , the Beenakker-Mazur method gives in most cases lower error than the renormalized Clausius-Mossotti approximation.

  11. Short time interval for condensation of high-temperature silicates in the solar accretion disk.

    PubMed

    Luu, Tu-Han; Young, Edward D; Gounelle, Matthieu; Chaussidon, Marc

    2015-02-01

    Chondritic meteorites are made of primitive components that record the first steps of formation of solids in our Solar System. Chondrules are the major component of chondrites, yet little is known about their formation mechanisms and history within the solar protoplanetary disk (SPD). We use the reconstructed concentrations of short-lived (26)Al in chondrules to constrain the timing of formation of their precursors in the SPD. High-precision bulk magnesium isotopic measurements of 14 chondrules from the Allende chondrite define a (26)Al isochron with (26)Al/(27)Al = 1.2(±0.2) × 10(-5) for this subset of Allende chondrules. This can be considered to be the minimum bulk chondrule (26)Al isochron because all chondrules analyzed so far with high precision (?50 chondrules from CV and ordinary chondrites) have an inferred minimum bulk initial ((26)Al/(27)Al) ? 1.2 × 10(-5). In addition, mineral (26)Al isochrons determined on the same chondrules show that their formation (i.e., fusion of their precursors by energetic events) took place from 0 Myr to ?2 Myr after the formation of their precursors, thus showing in some cases a clear decoupling in time between the two events. The finding of a minimum bulk chondrule (26)Al isochron is used to constrain the astrophysical settings for chondrule formation. Either the temperature of the condensation zone dropped below the condensation temperature of chondrule precursors at ?1.5 My after the start of the Solar System or the transport of precursors from the condensation zone to potential storage sites stopped after 1.5 My, possibly due to a drop in the disk accretion rate. PMID:25605942

  12. Variational data assimilation for the optimized ozone initial state and the short-time forecasting

    NASA Astrophysics Data System (ADS)

    Park, S.-Y.; Kim, D.-H.; Lee, S.-H.; Lee, H. W.

    2015-10-01

    In this study, we apply the four-dimensional variational (4D-Var) data assimilation to optimize initial ozone state and to improve the predictability of air quality. The numerical modeling systems used for simulations of atmospheric condition and chemical formation are the Weather Research and Forecasting (WRF) model and the Community Multiscale Air Quality (CMAQ) model. The study area covers the capital region of South Korea, where the surface measurement sites are relatively evenly distributed. The 4D-Var code previously developed for the CMAQ model is modified to consider background error in matrix form, and various numerical tests are conducted. The results are evaluated with an idealized covariance function for the appropriateness of the modified codes. The background error is then constructed using the NMC method with long-term modeling results, and the characteristics of the spatial correlation scale related to local circulation is analyzed. The background error is applied in the 4D-Var research, and a surface observational assimilation is conducted to optimize the initial concentration of ozone. The statistical results for the 12 h assimilation periods and the 120 observatory sites show a 49.4 % decrease in the root mean squred error (RMSE), and a 59.9 % increase in the index of agreement (IOA). The temporal variation of spatial distribution of the analysis increments indicates that the optimized initial state of ozone concentration is transported to inland areas by the clockwise-rotating local circulation during the assimilation windows. To investigate the predictability of ozone concentration after the assimilation window, a short-time forecasting is carried out. The ratios of the RMSE with assimilation vs. that without assimilation are 8 and 13 % for the +24 and +12 h, respectively. Such a significant improvement in the forecast accuracy is obtained solely by using the optimized initial state. The potential improvement in ozone prediction for both the daytime and night time with application of data assimilation is also presented.

  13. Short time interval for condensation of high-temperature silicates in the solar accretion disk

    PubMed Central

    Luu, Tu-Han; Young, Edward D.; Gounelle, Matthieu; Chaussidon, Marc

    2015-01-01

    Chondritic meteorites are made of primitive components that record the first steps of formation of solids in our Solar System. Chondrules are the major component of chondrites, yet little is known about their formation mechanisms and history within the solar protoplanetary disk (SPD). We use the reconstructed concentrations of short-lived 26Al in chondrules to constrain the timing of formation of their precursors in the SPD. High-precision bulk magnesium isotopic measurements of 14 chondrules from the Allende chondrite define a 26Al isochron with 26Al/27Al = 1.2(±0.2) × 10?5 for this subset of Allende chondrules. This can be considered to be the minimum bulk chondrule 26Al isochron because all chondrules analyzed so far with high precision (?50 chondrules from CV and ordinary chondrites) have an inferred minimum bulk initial (26Al/27Al) ? 1.2 × 10?5. In addition, mineral 26Al isochrons determined on the same chondrules show that their formation (i.e., fusion of their precursors by energetic events) took place from 0 Myr to ?2 Myr after the formation of their precursors, thus showing in some cases a clear decoupling in time between the two events. The finding of a minimum bulk chondrule 26Al isochron is used to constrain the astrophysical settings for chondrule formation. Either the temperature of the condensation zone dropped below the condensation temperature of chondrule precursors at ?1.5 My after the start of the Solar System or the transport of precursors from the condensation zone to potential storage sites stopped after 1.5 My, possibly due to a drop in the disk accretion rate. PMID:25605942

  14. The rate, luminosity function and time delay of non-Collapsar short GRBs

    NASA Astrophysics Data System (ADS)

    Wanderman, David; Piran, Tsvi

    2015-04-01

    We estimate the rate and the luminosity function of short (hard) Gamma-Ray Bursts (sGRBs) that are non-Collapsars, using the peak fluxes and redshifts of BATSE, Swift and Fermi GRBs. Following Bromberg et al., we select a sub-sample of Swift bursts which are most likely non-Collapsars. We find that these sGRBs are delayed relative to the global star formation rate (SFR) with a typical delay time of a 3-4 Gyr (depending on the SFR model). However, if two or three sGRB at high redshifts have been missed because of selection effects, a distribution of delay times of ? 1/t would be also compatible. The current event rate of these non-Collapsar sGRBs with Liso > 5 × 1049 erg s-1 is 4.1_{-1.9}^{+2.3} Gpc^{-3} yr^{-1}. The rate was significantly larger around z ˜ 1 and it declines since that time. The luminosity function we find is a broken power law with a break at 2.0_{-0.4}^{+1.4} × 10^{52} erg s^{-1} and power-law indices 0.95_{-0.1 2}^{+0.12} and 2.0_{-0.8}^{+1.0}. When considering the whole Swift sGRB sample we find that it is composed of two populations: one group (?60-80 per cent of Swift sGRBs) with the above rate and time delay and a second group (?20-40 per cent of Swift sGRBs) of potential `impostors' that follow the SFR with no delay. These two populations are in very good agreement with the division of sGRBs to non-Collapsars and Collapsars suggested recently by Bromberg et al. If non-Collapsar sGRBs arise from neutron star merger this rate suggest a detection rate of 3-100 yr-1 by a future gravitational wave detectors (e.g. Advanced Ligo/Virgo with detection horizon on 300 Mpc), and a co-detection with Fermi (Swift ) rate of 0.1-1 yr-1 (0.02-0.14 yr-1). We estimate that about 4 × 10^5 (f_b^{-1}/30) mergers took place in the Milky Way. If 0.025M? were ejected in each event this would have been sufficient to produce all the heavy r-process material in the Galaxy.

  15. Simulations of concentrated suspensions of rigid fibers: Relationship between short-time diffusivities and the long-time rotational diffusion

    NASA Astrophysics Data System (ADS)

    Cobb, Philip D.; Butler, Jason E.

    2005-08-01

    Brownian dynamics simulations of the behavior of suspensions of fibers demonstrate that the scaling of the rotational diffusivity with respect to the number density (nL3) is a sensitive function of the thickness and the parameter L2DR0/DT0, where DR0 is the rotational diffusivity at infinite dilution, DT0 is the average center-of-mass diffusivity at infinite dilution, and L is the fiber length. Existing theories for the long-time rotational diffusivities of rigid fibers in the semidilute and concentrated regimes fail to accurately account for the relationship with the dilute values of the rotational and translational diffusivities of the various physical models used to simulate the fibers. The concentration regime studied in this work ranges from a number density of nL3?0-150, which is below the transition from an isotropic to nematic state. The effect of the fiber thickness was studied by performing simulations of rods with aspect ratios (fiber length over diameter) of 25, 50, and 500, as well as performing projections for infinitely thin fibers. The excluded volume of the rods was enforced through the use of short-range potentials. For a rod with an aspect ratio of 50 with a parameter of L2DR0/DT0=9, which corresponds to a slender-body model of the individual fibers, the rotational diffusivity (DR) scales as DR/DR0˜(nL3)-1.9 in the concentration regime of 70?nL3?150. Similarly with a parameter of L2DR0/DT0=4, corresponding to a rigid-dumbbell model, the rotational diffusivity scales as DR/DR0˜(nL3)-1.1 over the same range of concentrations. For rods with aspect ratios of 25, it is observed that a difference in the scaling is seen for L2DR0/DT0?8, with higher values of this ratio exhibiting essentially the same scaling. Additional values of the ratio L2DR0/DT0 were investigated to determine the overall behavior of the suspension dynamics with respect to this parameter. These findings resolve discrepancies between simulation results for rotational diffusivities reported by previous investigators and provide new insights for the development of an accurate theory for the diffusivity of rigid rods suspended in solution.

  16. A New General Continuous-Time State Task Network Formulation for Short-Term Scheduling of Multipurpose Batch Plants

    E-print Network

    Grossmann, Ignacio E.

    of Multipurpose Batch Plants Christos T. Maravelias, Ignacio E. Grossmann Department of Chemical Engineering continuous time MILP model for the short-term scheduling of multipurpose batch plants is presented as it accounts for resources other than equipment and often gives better solutions being equally fast

  17. rainstorming is designed to help you come up with many ideas and suggestions in a short time. It can be

    E-print Network

    Farritor, Shane

    B rainstorming is designed to help you come up with many ideas and suggestions in a short time. It can be used to generate ideas for projects, help you visualize possible problems, and suggest enjoyable. record Select someone to write down the ideas as they develop (two people if the ideas start

  18. Testing convective transport on short time scales: Comparisons with mass divergence and ozone anomaly patterns about high

    E-print Network

    Martin, Randall

    the boundary layer to the free troposphere and affect the local rates of ozone and aerosol productionTesting convective transport on short time scales: Comparisons with mass divergence and ozone to construct anomaly patterns of divergence, cloud top frequency, and ozone mixing ratio about the high rain

  19. EUROGRAPHICS 2006 / D. W. Fellner and C. Hansen Short Papers Clothing the Masses: Real-Time Clothed Crowds With

    E-print Network

    O'Sullivan, Carol

    EUROGRAPHICS 2006 / D. W. Fellner and C. Hansen Short Papers Clothing the Masses: Real-Time Clothed would not be possible with current methods. In this paper, we wish to address this problem and devise. This method works well in some cases, but often results in the unrealistic bending of folds in the cloth

  20. Time-resolved diffraction profiles and atomic dynamics in short-pulse laser-induced structural transformations: Molecular dynamics study

    E-print Network

    Zhigilei, Leonid V.

    Time-resolved diffraction profiles and atomic dynamics in short-pulse laser-induced structural on the atomic-level structural rearrangements available from the simulations to the diffraction spectra measured of the irradiated surface and provides limited direct information on atomic structural rearrangements. Recent

  1. Short-time asymptotics of a rigorous path integral for N = 1 supersymmetric quantum mechanics on a Riemannian manifold

    SciTech Connect

    Fine, Dana S.; Sawin, Stephen

    2014-06-15

    Following Feynman's prescription for constructing a path integral representation of the propagator of a quantum theory, a short-time approximation to the propagator for imaginary-time, N = 1 supersymmetric quantum mechanics on a compact, even-dimensional Riemannian manifold is constructed. The path integral is interpreted as the limit of products, determined by a partition of a finite time interval, of this approximate propagator. The limit under refinements of the partition is shown to converge uniformly to the heat kernel for the Laplace-de Rham operator on forms. A version of the steepest descent approximation to the path integral is obtained, and shown to give the expected short-time behavior of the supertrace of the heat kernel.

  2. Estimating return periods of extreme values from relatively short time series of winds

    NASA Astrophysics Data System (ADS)

    Jonasson, Kristjan; Agustsson, Halfdan; Rognvaldsson, Olafur; Arfeuille, Gilles

    2013-04-01

    An important factor for determining the prospect of individual wind farm sites is the frequency of extreme winds at hub height. Here, extreme winds are defined as the value of the highest 10 minutes averaged wind speed with a 50 year return period, i.e. annual exceeding probability of 2% (Rodrigo, 2010). A frequently applied method to estimate winds in the lowest few hundred meters above ground is to extrapolate observed 10-meter winds logarithmically to higher altitudes. Recent study by Drechsel et al. (2012) showed however that this methodology is not as accurate as interpolating simulated results from the global ECMWF numerical weather prediction (NWP) model to the desired height. Observations of persistent low level jets near Colima in SW-Mexico also show that the logarithmic approach can give highly inaccurate results for some regions (Arfeuille et al., 2012). To address these shortcomings of limited, and/or poorly representative, observations and extrapolations of winds one can use NWP models to dynamically scale down relatively coarse resolution atmospheric analysis. In the case of limited computing resources one has typically to make a compromise between spatial resolution and the duration of the simulated period, both of which can limit the quality of the wind farm siting. A common method to estimate maximum winds is to fit an extreme value distribution (e.g. Gumbel, gev or Pareto) to the maximum values of each year of available data, or the tail of these values. If data are only available for a short period, e.g. 10 or 15 years, then this will give a rather inaccurate estimate. It is possible to deal with this problem by utilizing monthly or weekly maxima, but this introduces new problems: seasonal variation, autocorrelation of neighboring values, and increased discrepancy between data and fitted distribution. We introduce a new method to estimate return periods of extreme values of winds at hub height from relatively short time series of winds, simulated at a high spatial resolution. REFERENCES Arfeuille, Gilles J. M., A. L. Quintanilla, L. Zizumbo, and F. C. Viesca, 2012. Wind Resource Assessment in a Tropical Region with Complex Terrain using SODAR and a Meteorological Tower Network to Measure Low Level Jets and Boundary Layer Conditions. 15th AMS Conference on Mountain Meteorology, Steam boat Spring, Colorado, USA, August 2012. Available on-line: https://ams.confex.com/ams/15MountMet/webprogram/Manuscript/Paper210184/ARFEUILLLE_etal_15MountMet Conf_Aug2012.pdf Drechsel S., G. J. Mayr, J. W. Messner, and R. Stauffer, 2012: Wind Speeds at Heights Crucial for Wind Energy: Measurements and Verification of Forecasts. J. Appl. Meteor. Climatol., 51, 1602-1617. Rodrigo, J. S., 2010. State-of-the-Art of Wind Resource Assessment. CENER National Renewable Energy Center, Sarriguren, Spain. Available on-line: http://www.waudit-itn.eu/download.php?id=103&parent=79

  3. Revisiting the question: Does high-latitude solar activity lead low-latitude solar activity in time phase?

    SciTech Connect

    Kong, D. F.; Qu, Z. N.; Guo, Q. L.

    2014-05-01

    Cross-correlation analysis and wavelet transform methods are used to investigate whether high-latitude solar activity leads low-latitude solar activity in time phase or not, using the data of the Carte Synoptique solar filaments archive from 1919 March to 1989 December. From the cross-correlation analysis, high-latitude solar filaments have a time lead of 12 Carrington solar rotations with respect to low-latitude ones. Both the cross-wavelet transform and wavelet coherence indicate that high-latitude solar filaments lead low-latitude ones in time phase. Furthermore, low-latitude solar activity is better correlated with high-latitude solar activity of the previous cycle than with that of the following cycle, which is statistically significant. Thus, the present study confirms that high-latitude solar activity in the polar regions is indeed better correlated with the low-latitude solar activity of the following cycle than with that of the previous cycle, namely, leading in time phase.

  4. Revisiting the Question: Does High-latitude Solar Activity Lead Low-latitude Solar Activity in Time Phase?

    NASA Astrophysics Data System (ADS)

    Kong, D. F.; Qu, Z. N.; Guo, Q. L.

    2014-05-01

    Cross-correlation analysis and wavelet transform methods are used to investigate whether high-latitude solar activity leads low-latitude solar activity in time phase or not, using the data of the Carte Synoptique solar filaments archive from 1919 March to 1989 December. From the cross-correlation analysis, high-latitude solar filaments have a time lead of 12 Carrington solar rotations with respect to low-latitude ones. Both the cross-wavelet transform and wavelet coherence indicate that high-latitude solar filaments lead low-latitude ones in time phase. Furthermore, low-latitude solar activity is better correlated with high-latitude solar activity of the previous cycle than with that of the following cycle, which is statistically significant. Thus, the present study confirms that high-latitude solar activity in the polar regions is indeed better correlated with the low-latitude solar activity of the following cycle than with that of the previous cycle, namely, leading in time phase.

  5. Revisiting the Impact of Part-Time Work on Adolescent Adjustment: Distinguishing between Selection and Socialization Using Propensity Score Matching

    ERIC Educational Resources Information Center

    Monahan, Kathryn C.; Lee, Joanna M.; Steinberg, Laurence

    2011-01-01

    The impact of part-time employment on adolescent functioning remains unclear because most studies fail to adequately control for differential selection into the workplace. The present study reanalyzes data from L. Steinberg, S. Fegley, and S. M. Dornbusch (1993) using multiple imputation, which minimizes bias in effect size estimation, and 2 types…

  6. Revisiting Mr. Tall and Mr. Short

    ERIC Educational Resources Information Center

    Riehl, Suzanne M.; Steinthorsdottir, Olof Bjorg

    2014-01-01

    Ratio, rate, and proportion are central ideas in the Common Core State Standards (CCSS) for middle-grades mathematics (CCSSI 2010). These ideas closely connect to themes in earlier grades (pattern building, multiplicative reasoning, rational number concepts) and are the foundation for understanding linear functions as well as many high school…

  7. The Well of Time. Eighteen Short Stories from Philippine Contemporary Literature.

    ERIC Educational Resources Information Center

    Laygo, Teresito M., Comp.

    A collection of eighteen short stories by Filipino writers is presented. The selections represent a variety of images of Filipino culture, both urban and rural, and life styles in northern and southern Philippines. The aim of the anthology is that the student will learn to empathize with experience rendered in language, appreciate the Filipino…

  8. Short-Term Memory for Time in Children and Adults: A Behavioral Study and a Model

    ERIC Educational Resources Information Center

    Droit-Volet, Sylvie; Wearden, John; Delgado-Yonger, Maria

    2007-01-01

    This experiment investigated the effect of the short-term retention of duration on temporal discrimination in 5- and 8-year-olds, as well as in adults, by using an episodic temporal generalization task. In each age group, the participants' task was to compare two successive durations (a standard and a comparison duration) separated by a retention…

  9. Cognitive Abilities Explaining Age-Related Changes in Time Perception of Short and Long Durations

    ERIC Educational Resources Information Center

    Zelanti, Pierre S.; Droit-Volet, Sylvie

    2011-01-01

    The current study investigated how the development of cognitive abilities explains the age-related changes in temporal judgment over short and long duration ranges from 0.5 to 30 s. Children (5- and 9-year-olds) as well as adults were given a temporal bisection task with four different duration ranges: a duration range shorter than 1 s, two…

  10. Time and Frequency Domain Analysis of Molecular Absorption in Short-range

    E-print Network

    Politècnica de Catalunya, Universitat

    for transmission distances of several meters. In those cases, the propagation of terahertz waves is usual in the order of 1 µm to radiate electromagnetic waves in the terahertz band (0.1­10 THz) [3], [5 distances from one centimeter to several meters. Based on a recent channel model for short-range wireless

  11. Recognition Time for Words in Short-Term, Long-Term, or Both Memory Stores

    ERIC Educational Resources Information Center

    Mohs, Richard C.; Atkinson, Richard C.

    1974-01-01

    The present experiment was designed to investigate recognition memory processes in a task in which the items to be recognized were stored in long-term memory (LTM), in short-term memory (STM), or in both memory stores. (Author/RK)

  12. Modelling the water balance of a precise weighable lysimeter for short time scales

    NASA Astrophysics Data System (ADS)

    Fank, Johann; Klammler, Gernot; Rock, Gerhard

    2015-04-01

    Precise knowledge of the water fluxes between the atmosphere and the soil-plant system and the percolation to the groundwater system is of great importance for understanding and modeling water, solute and energy transfer in the atmosphere-plant-soil-groundwater system. Weighable lysimeters yield the most precise and realistic measures for the change of stored water volume (?S), Precipitation (P) which can be rain, irrigation, snow and dewfall and evapotranspiration (ET) as the sum of soil evaporation, evaporation of intercepted water and transpiration. They avoid systematic errors of standard gauges and class-A pans. Lysimeters with controlled suction at the lower boundary allow estimation of capillary rise (C) and leachate (L) on short time scales. Precise weighable large scale (surface >= 1 m2) monolithic lysimeters avoiding oasis effects allow to solve the water balance equation (P - ET - L + C ± ?S = 0) for a 3D-section of a natural atmosphere-plant-soil-system for a certain time period. Precision and accuracy of the lysimeter measurements depend not only on the precision of the weighing device but also on external conditions, which cannot be controlled or turned off. To separate the noise in measured data sets from signals the adaptive window and adaptive threshold (AWAT) filter (Peters et al., 2014) is used. The data set for the years 2010 and 2011 from the HYDRO-lysimeter (surface = 1 m2, depth = 1 m) in Wagna, Austria (Klammler and Fank, 2014) with a resolution of 0,01 mm for the lysimeter scale and of 0,001 mm for the leachate tank scale is used to evaluate the water balance. The mass of the lysimeter and the mass of the leachate tank is measured every two seconds. The measurements are stored as one minute arithmetic means. Based on calculations in a calibration period from January to May 2010 with different widths of moving window the wmax - Parameter for the AWAT filter was set to 41 minutes. A time series for the system mass ('upper boundary') of the lysimeter has been calculated by adding lysimeter mass and the leachate tank mass for every minute. Based on the resolution of the scales and an evaluation of noise in periods without precipitation and evaporation a dmin-value of 0.002 to filter the leachate tank measurements and a dmin-value of 0.012 was used to filter the lysimeter weight data and the upper boundary data. A mandatory requirement for the quantification of P or ET from lysimeter measurements is that in a reasonably small time interval, either P or ET is negligible. With this assumption, every increase in upper boundary data is interpreted as P. Every increase of seepage mass is interpreted as L, every decrease as C. ?S is evaluated from filtered lysimeter mass. ET is calculated using the water balance equation. The evaluation results are given as water balance components time series on a minute scale. P measured with the lysimeter for the two years 2010 and 2011 is 105 % of precipitation measured with a standard tipping bucket gauge 100 m beside the lysimeter. While P during the summer season (April to September) is very close to standard precipitation measurement, P during the winter season is more than 120 % of tipping bucket precipitation. Meissner et al. (2007) showed that P includes precipitation of dewfall and rime. A detailed evaluation of the HYDRO-Lysimeter in Wagna showed, that precipitation in the night and not recognized with the standard tipping bucket (interpreted as dew or rime) is about 1 % of P, the highest monthly sums (> 1 mm) are recognized from August to November. Klammler, G. and Fank, J.: Determining water and nitrogen balances for beneficial management practices using lysimeters at Wagna test site (Austria). Science of the Total Environment 499 (2014) 448-462. Meissner, R., Seeger, J., Rupp, H., Seyfarth, M., and Borg, H.: Measurement of dew, fog, and rime with a high-precision gravitation lysimeter, J. Plant Nutr. Soil Sci. 2007, 170, 335-344. Peters, A., Nehls, T., Schonsky, H., and Wessolek, G.: Separating precipitation and evapotranspiration from noise - a

  13. Revisiting the Regenerative Possibilities of Ortiz

    ERIC Educational Resources Information Center

    Duques, Matthew

    2004-01-01

    The author of this article revisits Simon Ortiz's poem, "From Sand Creek," in which the latter can in so few words convey both the horrific tragedy of conquest and colonization, while at the same time find a space for possibility, a means for recovery that is never about forgetting but always occurs as a kind of recuperative remembering. Ortiz…

  14. Broadcast Flooding Revisited: Survivability and Latency

    E-print Network

    Riedi, Rudolf H.

    Broadcast Flooding Revisited: Survivability and Latency Petteri Mannersalo VTT Technical Research University Email: riedi@rice.edu Abstract--This paper addresses the dynamics of broadcast flooding in random wireless ad hoc networks. In particular, we study the subset of nodes covered by a flood as well as timing

  15. Application of a short-time version of the Equalization-Cancellation model to speech intelligibility experiments with speech maskers.

    PubMed

    Wan, Rui; Durlach, Nathaniel I; Colburn, H Steven

    2014-08-01

    A short-time-processing version of the Equalization-Cancellation (EC) model of binaural processing is described and applied to speech intelligibility tasks in the presence of multiple maskers, including multiple speech maskers. This short-time EC model, called the STEC model, extends the model described by Wan et al. [J. Acoust. Soc. Am. 128, 3678-3690 (2010)] to allow the EC model's equalization parameters ? and ? to be adjusted as a function of time, resulting in improved masker cancellation when the dominant masker location varies in time. Using the Speech Intelligibility Index, the STEC model is applied to speech intelligibility with maskers that vary in number, type, and spatial arrangements. Most notably, when maskers are located on opposite sides of the target, this STEC model predicts improved thresholds when the maskers are modulated independently with speech-envelope modulators; this includes the most relevant case of independent speech maskers. The STEC model describes the spatial dependence of the speech reception threshold with speech maskers better than the steady-state model. Predictions are also improved for independently speech-modulated noise maskers but are poorer for reversed-speech maskers. In general, short-term processing is useful, but much remains to be done in the complex task of understanding speech in speech maskers. PMID:25096111

  16. Application of a short-time version of the Equalization-Cancellation model to speech intelligibility experiments with speech maskers

    PubMed Central

    Wan, Rui; Durlach, Nathaniel I.; Colburn, H. Steven

    2014-01-01

    A short-time-processing version of the Equalization-Cancellation (EC) model of binaural processing is described and applied to speech intelligibility tasks in the presence of multiple maskers, including multiple speech maskers. This short-time EC model, called the STEC model, extends the model described by Wan et al. [J. Acoust. Soc. Am. 128, 3678–3690 (2010)] to allow the EC model's equalization parameters ? and ? to be adjusted as a function of time, resulting in improved masker cancellation when the dominant masker location varies in time. Using the Speech Intelligibility Index, the STEC model is applied to speech intelligibility with maskers that vary in number, type, and spatial arrangements. Most notably, when maskers are located on opposite sides of the target, this STEC model predicts improved thresholds when the maskers are modulated independently with speech-envelope modulators; this includes the most relevant case of independent speech maskers. The STEC model describes the spatial dependence of the speech reception threshold with speech maskers better than the steady-state model. Predictions are also improved for independently speech-modulated noise maskers but are poorer for reversed-speech maskers. In general, short-term processing is useful, but much remains to be done in the complex task of understanding speech in speech maskers. PMID:25096111

  17. Kidney stone imaging with 3D ultra-short echo time (UTE) magnetic resonance imaging. A phantom study.

    PubMed

    Ibrahim, El-Sayed H; Pooley, Robert A; Bridges, Mellena D; Cernigliaro, Joseph G; Haley, William E

    2014-01-01

    Computed tomography (CT) is the current gold standard for imaging kidney stones, albeit at the cost of radiation exposure. Conventional magnetic resonance imaging (MRI) sequences are insensitive to detecting the stones because of their appearance as a signal void. With the development of 2D ultra-short echo-time (UTE) MRI sequences, it becomes possible to image kidney stones in vitro. In this work, we optimize and implement a modified 3D UTE MRI sequence for imaging kidney stones embedded in agarose phantoms mimicking the kidney tissue and in urine phantoms at 3.0T. The proposed technique is capable of imaging the stones with high spatial resolution in a short scan time. PMID:25570462

  18. Human brain detects short-time nonlinear predictability in the temporal fine structure of deterministic chaotic sounds

    NASA Astrophysics Data System (ADS)

    Itoh, Kosuke; Nakada, Tsutomu

    2013-04-01

    Deterministic nonlinear dynamical processes are ubiquitous in nature. Chaotic sounds generated by such processes may appear irregular and random in waveform, but these sounds are mathematically distinguished from random stochastic sounds in that they contain deterministic short-time predictability in their temporal fine structures. We show that the human brain distinguishes deterministic chaotic sounds from spectrally matched stochastic sounds in neural processing and perception. Deterministic chaotic sounds, even without being attended to, elicited greater cerebral cortical responses than the surrogate control sounds after about 150 ms in latency after sound onset. Listeners also clearly discriminated these sounds in perception. The results support the hypothesis that the human auditory system is sensitive to the subtle short-time predictability embedded in the temporal fine structure of sounds.

  19. Short Contact Time Direct Coal Liquefactionn Using a Novel Batch Reactor. Quarterly Report. May 16 - August 15, 1996

    SciTech Connect

    He Huang; Michael T. Klein; William H. Calkins

    1996-08-30

    The objective of this research is to optimize the design and operation of the bench scale batch reactor (SCTBR) for studying direct coal liquefaction at short contact times (.01 to 10 minutes or longer). Additional objectives are to study the kinetics of direct coal liquefaction particularly at short reaction times and to investigate the role of organic oxygen components of coal and their reaction pathways during coal liquefaction. Many of those objectives have already been achieved. This quarterly report discusses further kinetic studies of the liquefaction of Illinois #6 bituminous coal, Wyodak-Anderson subbituminous coal, and Pittsburgh #8 bituminous coal. The thermodynamic characteristics of the extraction stage at the start of the liquefaction process in the liquefaction of Illinois #6 coal is also discussed. Further work has also been done to attempt to clarify the role of the liquefaction solvent in the direct liquefaction process.

  20. Short contact time direct coal liquefaction using a novel batch reactor. Quarterly progress report, January 1--May 15, 1995

    SciTech Connect

    Klein, M.T.; Calkins, W.H.

    1995-05-31

    The objective of this research is to optimize the design and operation of the bench scale batch reactor for coal liquefaction at short contact times (0.01 to 10 minutes or longer). Additional objectives are to study the kinetics of direct coal liquefaction particularly at short reaction times, and to investigate the role of the organic oxygen components of coal and their reaction pathways during liquefaction. Experimental progress is reported for uncatalyzed liquefactions, catalyzed liquefactions, liquefaction in the presence of solvents other than tetralin, and kinetics of gas formation during coal liquefaction. Analytical methods were developed for the determination of the boiling range of coal liquids by thermogravimetric analysis and the determination of phenolic hydroxyl in coal, coal liquids, and coal residues.

  1. Numerical study of the effect of normalised window size, sampling frequency, and noise level on short time Fourier transform analysis

    SciTech Connect

    Ota, T. A.

    2013-10-15

    Photonic Doppler velocimetry, also known as heterodyne velocimetry, is a widely used optical technique that requires the analysis of frequency modulated signals. This paper describes an investigation into the errors of short time Fourier transform analysis. The number of variables requiring investigation was reduced by means of an equivalence principle. Error predictions, as the number of cycles, samples per cycle, noise level, and window type were varied, are presented. The results were found to be in good agreement with analytical models.

  2. Effect of short-time hydrothermal pretreatment of kitchen waste on biohydrogen production: fluorescence spectroscopy coupled with parallel factor analysis.

    PubMed

    Li, Mingxiao; Xia, Tianming; Zhu, Chaowei; Xi, Beidou; Jia, Xuan; Wei, Zimin; Zhu, Jinlong

    2014-11-01

    The enhancement of bio-hydrogen production from kitchen waste by a short-time hydrothermal pretreatment at different temperatures (i.e., 90°C, 120°C, 150°C and 200°C) was evaluated. The effects of temperature for the short-time hydrothermal pretreatment on kitchen waste protein conversion and dissolved organic matter characteristics were investigated in this study. A maximum bio-hydrogen yield of 81.27mL/g VS was acquired at 200°C by the short-time hydrothermal pretreatment during the anaerobic fermentative hydrogen production. Analysis of the dissolved organic matter composition showed that the protein-like peak dominated and that three fluorescent components were separated using fluorescence excitation-emission matrix spectra coupled with the parallel factor model. The maximum fluorescence intensities of protein-like components decomposed through the parallel factor analysis has a significant correlation with the raw protein concentration, showed by further correlation analysis. This directly impacted the hydrogen production ability. PMID:25280046

  3. Revisiting the Posttherapeutic Cure Criterion in Chagas Disease: Time for New Methods, More Questions, Doubts, and Polemics or Time to Change Old Concepts?

    PubMed Central

    de Lana, Marta; Martins-Filho, Olindo Assis

    2015-01-01

    One of the most relevant issues beyond the effectiveness of etiological treatment of Chagas disease is the lack of consensual/feasible tools to identify and certify the definitive parasitological cure. Several methods of distinct natures (parasitological, serological, and molecular) have been continuously proposed and novel perspectives are currently under investigation. Although the simultaneous use of distinct tests may offer better contributions and advances, it also leads to controversies of interpretation, with lack of mutual consent of cure criterion amongst researchers and physicians. In fact, when distinct host compartments (blood/tissues) are evaluated and explored, novel questions may arise due to the nature and sensitivity limit of each test. This short analytical review intends to present a chronological and critical overview and discuss the state-of-the-art distinct devices available for posttherapeutic cure assessment in Chagas disease, their contributions, meanings, and interpretation, aiming to point out the major gaps and propose novel insight for future perspectives of posttherapeutic management of Chagas disease patients. PMID:26583124

  4. CRISPR revisited: structure prediction of CRISPR repeats Sita Lange1

    E-print Network

    Will, Sebastian

    CRISPR revisited: structure prediction of CRISPR repeats Sita Lange1 , Omer S. Alkhnbashi 1 Regularly Interspaced Short Palindromic Repeats (CRISPRs), illustrated to the right. The CRISPR transcripts sequences have been found to match foreign virus or plasmid DNA. A set of CRISPR-associated (Cas) proteins

  5. Time-resolved neuroimaging of visual short term memory consolidation by post-perceptual attention shifts.

    PubMed

    Hecht, Marcus; Thiemann, Ulf; Freitag, Christine M; Bender, Stephan

    2016-01-15

    Post-perceptual cues can enhance visual short term memory encoding even after the offset of the visual stimulus. However, both the mechanisms by which the sensory stimulus characteristics are buffered as well as the mechanisms by which post-perceptual selective attention enhances short term memory encoding remain unclear. We analyzed late post-perceptual event-related potentials (ERPs) in visual change detection tasks (100ms stimulus duration) by high-resolution ERP analysis to elucidate these mechanisms. The effects of early and late auditory post-cues (300ms or 850ms after visual stimulus onset) as well as the effects of a visual interference stimulus were examined in 27 healthy right-handed adults. Focusing attention with post-perceptual cues at both latencies significantly improved memory performance, i.e. sensory stimulus characteristics were available for up to 850ms after stimulus presentation. Passive watching of the visual stimuli without auditory cue presentation evoked a slow negative wave (N700) over occipito-temporal visual areas. N700 was strongly reduced by a visual interference stimulus which impeded memory maintenance. In contrast, contralateral delay activity (CDA) still developed in this condition after the application of auditory post-cues and was thereby dissociated from N700. CDA and N700 seem to represent two different processes involved in short term memory encoding. While N700 could reflect visual post processing by automatic attention attraction, CDA may reflect the top-down process of searching selectively for the required information through post-perceptual attention. PMID:26571051

  6. Vessel failure time for a low-pressure short-term station blackout in a BWR-4

    SciTech Connect

    Carbajo, J.J. )

    1993-01-01

    A low-pressure, short-term station blackout severe accident sequence has been analyzed using the MELCOR code, version 1.8.1, in a boiling water reactor (BWR)-4. This paper presents a sensitivity study evaluating the effect of several MELCOR input parameters on vessel failure time. Results using the MELCOR/CORBH package and the BWRSAR code are also presented and compared to the MELCOR results. These calculated vessel failure times are discussed, and a judgment is offered as to which is the most realistic.

  7. Short-time heat impulse intensification of heat transfer in liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Balakin, B. V.; Delov, M. I.; Kutsenko, K. V.; Lavrukhin, A. A.; Merinov, I. G.

    2015-04-01

    The cryogenic technology deals with fluids produced from gases after liquefaction. Boiling of cryogenic fluids is frequently characterized by a hysteresis of their boiling curve. The present experimental work demonstrates an opportunity to intensify heat transfer in those fluids by means of short-term heat impulsion from a heater. The intensification takes place due to the impulse-induced transition of heat transfer regime from natural convection towards nucleate boiling. The process takes place when the impulse magnitude overcomes certain minimum value that was quantified experimentally. We also propose a theoretical expression for the minimum energy that is in agreement with the experimental data.

  8. No Clear Association between Impaired Short-Term or Working Memory Storage and Time Reproduction Capacity in Adult ADHD Patients

    PubMed Central

    Mette, Christian; Grabemann, Marco; Zimmermann, Marco; Strunz, Laura; Scherbaum, Norbert; Wiltfang, Jens; Kis, Bernhard

    2015-01-01

    Objective Altered time reproduction is exhibited by patients with adult attention deficit hyperactivity disorder (ADHD). It remains unclear whether memory capacity influences the ability of adults with ADHD to reproduce time intervals. Method We conducted a behavioral study on 30 ADHD patients who were medicated with methylphenidate, 29 unmedicated adult ADHD patients and 32 healthy controls (HCs). We assessed time reproduction using six time intervals (1 s, 4 s, 6 s, 10 s, 24 s and 60 s) and assessed memory performance using the Wechsler memory scale. Results The patients with ADHD exhibited lower memory performance scores than the HCs. No significant differences in the raw scores for any of the time intervals (p > .05), with the exception of the variability at the short time intervals (1 s, 4 s and 6 s) (p < .01), were found between the groups. The overall analyses failed to reveal any significant correlations between time reproduction at any of the time intervals examined in the time reproduction task and working memory performance (p > .05). Conclusion We detected no findings indicating that working memory might influence time reproduction in adult patients with ADHD. Therefore, further studies concerning time reproduction and memory capacity among adult patients with ADHD must be performed to verify and replicate the present findings. PMID:26221955

  9. Potential overestimation in primary and new productions of phytoplankton from a short time incubation method

    NASA Astrophysics Data System (ADS)

    Lee, Sang Heon; Joo, HuiTae; Lee, Jang Han; Kang, Jae Joong; Lim, Jae-Hyun; Yun, Mi Sun; Lee, Jae Hyung; Kang, Chang-Keun

    2015-09-01

    A short (4-5 hour) incubation method for a 13C-15N dual isotope tracer technique has been widely applied for the measurements of daily primary and new productions of phytoplankton. However, there has been no research conducted to determine if there are any differences in the estimated daily productions between short incubation periods and 24 hour incubations. Based on hourly uptake rates estimated from a 4 hour incubation at a coastal site in the East/Japan Sea, the daily carbon and nitrogen uptake rates of total phytoplankton were approximately 60% overestimated compared to those derived from a 24 hour incubation. Especially for large phytoplankton, the daily carbon uptake rates based on the 4 hour incubation were greatly overestimated (> 200%). In contrast, the daily rates of small phytoplankton were not significantly different between the two different incubations. This is mainly because the daily carbon and nitrogen uptake rates of large phytoplankton were significantly correlated with light intensity. Consequently, the contributions of small phytoplankton were underestimated whereas large phytoplankton contributions were overestimated in daily carbon and nitrogen uptake rates based on a 4 hour incubation. Further investigations into these potential overestimations in daily carbon and nitrogen uptake rates of phytoplankton, especially for large size cells, will be needed to be carried out in order to obtain better estimations of annual primary and new productions.

  10. Exobiology revisited

    NASA Astrophysics Data System (ADS)

    Klein, H. P.

    The term ``Exobiology'' was introduced about 25 years ago, at a time when intensive discussions were under way concerning plans for the biological exploration of Mars. The search for life on Mars was to be a critical test of the concept of chemical evolution- not an end in itself. After the Viking mission, when it became apparent that prospects were dim for the discovery of extraterrestrial life within our solar system, many people concluded that this new field of endeavor would soon expire. Quite the contrary, over the past decade, the field has broadened considerably into a multidisciplinary approach to understanding the circumstances that led to the origin of life and the interplay between the evolution of this planet and its biota.

  11. Revisiting Buruli ulcer.

    PubMed

    Yotsu, Rie R; Murase, Chiaki; Sugawara, Mariko; Suzuki, Koichi; Nakanaga, Kazue; Ishii, Norihisa; Asiedu, Kingsley

    2015-11-01

    Buruli ulcer (BU), or Mycobacterium ulcerans infection, is a new emerging infectious disease which has been reported in over 33 countries worldwide. It has been noted not only in tropical areas, such as West Africa where it is most endemic, but also in moderate non-tropical climate areas, including Australia and Japan. Clinical presentation starts with a papule, nodule, plaque or edematous form which eventually leads to extensive skin ulceration. It can affect all age groups, but especially children aged between 5 and 15 years in West Africa. Multiple-antibiotic treatment has proven effective, and with surgical intervention at times of severity, it is curable. However, if diagnosis and treatment is delayed, those affected may be left with life-long disabilities. The disease is not yet fully understood, including its route of transmission and pathogenesis. However, due to recent research, several important features of the disease are now being elucidated. Notably, there may be undiagnosed cases in other parts of the world where BU has not yet been reported. Japan exemplifies the finding that awareness among dermatologists plays a key role in BU case detection. So, what about in other countries where a case of BU has never been diagnosed and there is no awareness of the disease among the population or, more importantly, among health professionals? This article will revisit BU, reviewing clinical features as well as the most recent epidemiological and scientific findings of the disease, to raise awareness of BU among dermatologists worldwide. PMID:26332541

  12. Short-term information pattern in optokinetic nystagmus amplitude time series.

    PubMed

    Aasen, T; Goplen, F; Nordahl, S H G

    2013-01-01

    In this paper we analyzed optokinetic nystagmus (OKN) signals for underlying information patterns. Fourteen OKN signals were recorded in five healthy subjects. First, we tested the correlation between nystagmus slow and fast phases. Previously, it has been suggested that the correlation is higher between the amplitude of the slow phase and the following fast phase, compared to the correlation between the fast phase and the following slow phase. However, we found no such difference. This is in agreement with the view that the saccade performed by the eye is not determined by the previous slow phase, but is free to move voluntarily in order to focus on an object of interest. Second, we analyzed the information entropy contained in the sequence of optokinetic nystagmus amplitudes, and found a short-term information pattern. Further analysis of these patterns could eventually lead to more knowledge about the vestibular and oculomotor systems. PMID:23788134

  13. Amyoplasia revisited.

    PubMed

    Hall, Judith G; Aldinger, Kimberly A; Tanaka, Kimi I

    2014-03-01

    Amyoplasia is a specific type and the most common form of arthrogryposis (multiple congenital contractures). It is a clinical diagnosis at this time. Care should be used making the diagnosis because of the implications for recurrence, natural history, associated anomalies, and both etiology and pathogenesis. We reviewed over 600 published reports and 2,500 individual records to identify the 560 individuals reported here. Affected limbs had characteristic positions with fatty-fibrous replacement of muscle. Upper limb involvement was usually characterized by extended elbows. Lower limbs were held in various positions at birth; however, equinovarus positioning of feet was almost always present. Symmetric involvement was common. Among 560 affected individuals, subtypes were identified: four-limb symmetric involvement (331/560 = 55.9%), severe involvement (41/560 = 7.3%), three-limb involvement (27/560 = 4.8%), upper limb only Amyoplasia (ULA; 94/560 = 16.8%), and lower limb only Amyoplasia (LLA; 25/560 = 15.5%). Discordant monozygotic twinning was increased, occurring in 6.6% (37/560; OR 10.9). A variety of additional anomalies were seen, attributed to apparent vascular compromise. Gastrointestinal vascular compromise-type anomalies were present in 9.1% (51/560), trunk muscle defects in another 2.7% (15/560), digit compromise in 12.1% (68/560), constriction rings in 4.3% (24/560), and perinatal long bone fractures in 10.5% (59/560). Although prenatal ultrasound became the standard of care in 1990, only about one quarter of affected pregnancies were diagnosed prenatally since 1990. Amyoplasia appears to be completely sporadic. Novel pathogenetic mechanisms for the congenital anomalies seen in Amyoplasia need to be identified. PMID:24459070

  14. Short-time-scale (year) variations of petroleum fluids from the U.S. Gulf Coast

    NASA Astrophysics Data System (ADS)

    Whelan, Jean K.; Eglinton, Lorraine; Kennicutt, Mahlon C.; Qian, Yaorong

    2001-10-01

    Evolving short-term (less than 5 yr) compositional changes in hydrocarbon charge from some Eugene Island Block 330 (EI-330) wells are demonstrated. Storage, analytical, and production artifacts are shown to be minimal. In some wells, compositions remain constant from 1985 to 1993, whereas in others in the same reservoir, significant changes are observed. In some cases, temporal variability is greater than spatial variability. Maximum temporal change is strongest for specific compounds: toluene and C 6 to C 9 normal alkanes, but is also observed to a lesser extent for higher-molecular-weight components (up to n-C 32). Principal coordinate analysis shows the highest degree of overall temporal compositional change over an 8-yr period in the shallowest wells where there is also evidence of biodegradation. Small temporal compositional changes are also observed in two deeper wells that are below the thermal window favorable for biodegradation. An exception is an unusual oil, where a very large increase in toluene, as well as smaller changes in a number of n-alkanes, was observed in 1993. The ? 13C compound-specific isotopic signature of toluene, in addition to several other C 7-C 8 compounds in this oil, yields convincing evidence that it is related to the same family as other EI-330 oils and unlikely to be due to a drilling or laboratory contaminant. Minor isotopic differences in other C 7 compounds (1.5‰) are consistent with extensive gas washing of this oil. The short-term compositional changes in EI-330 oils are attributed to gas washing, which causes overprinting of biodegraded oils with light n-alkanes in shallower GA and HB reservoirs where oils are currently being biodegraded in situ. Patterns of smaller changes in heavier compounds in both shallower and deeper wells are also consistent with this interpretation.

  15. Caterpillars selected for large body size and short development time are more susceptible to oxygen-related stress

    PubMed Central

    Harrison, Jon F; Cease, Arianne J; VandenBrooks, John M; Albert, Todd; Davidowitz, Goggy

    2013-01-01

    Recent studies suggest that higher growth rates may be associated with reduced capacities for stress tolerance and increased accumulated damage due to reactive oxygen species. We tested the response of Manduca sexta (Sphingidae) lines selected for large or small body size and short development time to hypoxia (10 kPa) and hyperoxia (25, 33, and 40 kPa); both hypoxia and hyperoxia reduce reproduction and oxygen levels over 33 kPa have been shown to increase oxidative damage in insects. Under normoxic (21 kPa) conditions, individuals from the large-selected (big-fast) line were larger and had faster growth rates, slightly longer developmental times, and reduced survival rates compared to individuals from a line selected for small size (small-fast) or an unselected control line. Individuals from the big-fast line exhibited greater negative responses to hyperoxia with greater reductions in juvenile and adult mass, growth rate, and survival than the other two lines. Hypoxia generally negatively affected survival and growth/size, but the lines responded similarly. These results are mostly consistent with the hypothesis that simultaneous acquisition of large body sizes and short development times leads to reduced capacities for coping with stressful conditions including oxidative damage. This result is of particular importance in that natural selection tends to decrease development time and increase body size. PMID:23762517

  16. FALSE DETERMINATIONS OF CHAOS IN SHORT NOISY TIME SERIES. (R828745)

    EPA Science Inventory

    A method (NEMG) proposed in 1992 for diagnosing chaos in noisy time series with 50 or fewer observations entails fitting the time series with an empirical function which predicts an observation in the series from previous observations, and then estimating the rate of divergenc...

  17. Panspermia revisited

    NASA Astrophysics Data System (ADS)

    Horneck, Gerda

    "Panspermia", coined by S. Arrhenius in 1903, suggests that microscopic forms of life, e.g., bacterial spores, can be dispersed in space by the radiation pressure from the Sun thereby seeding life from one planet to another or even beyond our Solar System. Being ignored for almost the rest of the century, the scenario of interplanetary transfer of life has received increased support from recent discoveries, such as the detection of Martian meteorites and the high resistance of microorganisms to outer space conditions. With the aid of space technology and adequate laboratory devices the following decisive step required for viable transfer from one planet to another have been tested: (i) the escape process, i.e. impact ejection into space; (ii) the journey through space over extended periods of time; and (iii) the landing process, i.e. non-destructive deposition of the biological material on another planet. In systematic shock recovery experiments within a pressure range observed in Martian meteorites (5-50 GPa) a vital launch window of 5-40 GPa has been determined for spores of Bacillus subtilis and the lichen Xanthoria elegans, whereas this window was restricted to 5-10 GPa for the endolithic cyanobaterium Chroococcidiopsis. Traveling through space implies exposure to high vacuum, an intense radiation regime of cosmic and solar origin and high temperature fluctuations. In several space experiments the biological efficiency of these different space parameters has been tested: extraterrestrial solar UV radiation has exerted the most deleterious effects to viruses, as well as to bacterial and fungal spores; however shielding against this intense insolation resulted in 70 % survival of B. subtilis spores after spending 6 years in outer space. Lichens survived 2 weeks in space, even without any shielding. The entry process of microorganisms has been recently tested in the STONE facility attached to the heat shield of a reentry capsule. The data support the scenario of "Lithopanspermia", which assumes that impact-expelled rocks serve as interplanetary transfer vehicles for microorganisms colonizing those rocks. Literature: St¨ffler D, Horneck G, Ott S, Hornemann, U, Cockell CS, Moeller R, Meyer C, de Vera J-P, o Fritz J, Artemieva NA,.Experimental evidence for the potential impact ejection of viable microorganisms from Mars and Mars-like planets (2007) Icarus, 186, 585-588. Sancho, L.G., de la Torre, R., Horneck, G., Ascaso, C., de los Rios, A., Pintado, A., Wierzchos, J. and Schuster, M. (2007) Lichens survive in space: Results from the 2005 LICHENS experiment. Astrobiology, 7, 443-454. Mileikowsky C, Cucinotta F, Wilson J W, Gladman B, Horneck G, Lindegren L, Melosh J, Rickman H, Valtonen M, Zheng J Q (2000) Natural transfer of viable microbes In space, Part 1: From Mars to Earth and Earth to Mars, Icarus, 145, 391-427. Nicholson WL, Munakata N, Horneck G, Melosh HJ, and Setlow P (2000) Resistance of Bacillus endospores to extreme terrestrial and extraterrestrial environments, Microb. Mol. Biol. Rev. 64, 548-572.

  18. Time Resolved Studies of ZnO (Eu) Nanostructure Luminescence Using Short Synchrotron Radiation Pulses

    NASA Astrophysics Data System (ADS)

    Heigl, F.; Jürgensen, A.; Zhou, X.-T.; Murphy, M.; Ko, J. Y. P.; Lam, S.; Sham, T. K.; Regier, T.; Blyth, R. I. R.; Coulthard, I.; Zuin, L.; Hu, Y.-F.; Armelao, L.; Gordon, R.; Brewe, D.

    2007-02-01

    X-ray excited optical luminescence (XEOL) is a well established technique to study nano structured light emitting materials. XEOL bares the essential features necessary for the study of advanced nano structured materials like element specifity, good quantum efficiency, and easy approach for time resolution. Being sensitive to the geometry of the material on a nano-scale, luminescence gives insight into the phenomenologic correlation of structural, optical, and electronic properties. Besides structural aspects we study the time behavior of nanostructured ZnO (Eu) in a pump-probe like experiment, using the time structure of synchrotron radiation.

  19. Identifying monomer phases and cluster phases in lysozyme solutions by studying the temperature dependence of the short-time dynamics

    SciTech Connect

    Baglioni, P; Chen, Wei-Ren; Falus, Peter; Faraone, Antonio; Fratini, Emiliano; Hong, Kunlun; Liu, Yun; Porcar, L.

    2012-01-01

    Recently experiments that combine both small angle neutron scattering (SANS) and Neutron Spin Echo (NSE) have demonstrated that dynamic clusters can form in concentrated lysozyme solutions when there is a right combination of a short-ranged attraction and a long-ranged electrostatic repulsion. In this paper, we study the temperature effect on the dynamic cluster formation and try to pinpoint the transition concentration from a monomer phase to a cluster phase. Interestingly at even a relatively high concentration (10 % mass fraction), despite the significant change of the SANS patterns that are associated with the change of the short-ranged attraction among proteins, the normalized short-time self-diffusion coefficient is not affected. This is interpreted due to the fact that there is no cluster formation at this condition. However, at larger concentrations such as 17.5 % and 22.5 % mass fraction, we show that the average hydrodynamic radius increase significantly and causes a large decrease of the normalized self-diffusion coefficient when the temperature is changed from 25 oC to 5 oC indicating the formation of dynamic clusters in solution.

  20. Time-dependent intensity and phase measurements of ultrashort laser pulses as short as 10 fs

    SciTech Connect

    DeLong, K.W.; Fittinghoff, D.N.; Ladera, C.L.; Trebino, R.; Taft, G.; Rundquist, A.; Murnane, M.M.; Kapteyn, H.C.; Christov, I.P.

    1995-05-01

    Frequency-Resolved Optical Gating (FROG) measures the time-dependent intensity and phase of an ultrashort laser pulse. Using FROG, we have tested theories for the operation of sub{minus}10 fs laser oscillators.

  1. Eclipse Timing Variations of Short-Period Binaries in the Kepler Field

    NASA Astrophysics Data System (ADS)

    Conroy, Kyle E.; Prsa, A.; Orosz, J.; Welsh, W.; Kepler Team

    2012-05-01

    2165 eclipsing binaries in the Kepler field have been identified and characterized by Prsa et al. (2011) and Slawson et al. (2011). Due to Kepler's essentially uninterrupted observing, we are presented with an opportunity to precisely measure eclipse timings and detect any underlying signals due to third bodies, apsidal motion, dynamical interaction, etc. Orosz et al. (2012; in prep.) are focusing on eclipse timing variations of binaries with periods longer than about 1 day. For shorter period binaries, Kepler's 30 minute exposure time causes significant smearing of lightcurves and may induce spurious signal for binaries of near-commensurate periods. These effects, along with imperfections in the detrending process, can result in systematic artifacts. To compute eclipse timing variations, we fit a polynomial chain to the phased lightcurve data and slide this function across each eclipse to find the corresponding time that minimizes the residuals. We tested this method on synthetic data and apply it to Kepler data. We present statistical results on eclipse timings and discuss our findings. This project is supported through the Kepler Participating Scientist Award NSR303065.

  2. Impact of Short-Stay Urethroplasty on Health-Related Quality of Life and Patient's Perception of Timing of Discharge

    PubMed Central

    Okafor, Henry; Nikolavsky, Dmitriy

    2015-01-01

    Objective. To evaluate health-related quality of life in patients after a short-stay or outpatient urethroplasty. Methods. Over a 2-year period a validated health-related quality-of-life questionnaire, EuroQol (EQ-5D), was administered to all patients after urethroplasty. Postoperatively patients were offered to be sent home immediately or to stay overnight. Within 24 hours after discharge they were assessed for mobility, self-care, usual activities, pain or discomfort, and anxiety and depression. An additional question assessing timing of discharge was added to the survey. Clinical and operative characteristics were examined. Results. Forty-eight patients after anterior urethroplasty completed the survey. Mean age and mean stricture length were 51.6 years (21–78) and 60?mm (5–200?mm), respectively. Most etiologies were idiopathic (50% n = 24), trauma (19%, n = 9), and iatrogenic (19%, n = 9). Forty-one patients (85%) stayed overnight, while 7 patients (15%) chose to be discharged the same day. Overall, ninety-six percent were discharged within 23 hours of surgery. In the short-stay and the outpatient cohorts, 90% and 86%, respectively, felt they were discharged on time. No patient reported a severe problem with postoperative pain or mobility. Conclusions. The majority of patients discharged soon after their procedure felt that discharge timing was appropriate and their health-related quality of life was only minimally affected. PMID:26494996

  3. A new monitor set for the determination of neutron flux parameters in short-time k0-NAA

    NASA Astrophysics Data System (ADS)

    Kubešová, Marie; Ku?era, Jan; Fikrle, Marek

    2011-11-01

    Multipurpose research reactors such as LVR-15 in ?ež require monitoring of the neutron flux parameters (f, ?) in each batch of samples analyzed when k0 standardization in NAA is to be used. The above parameters may change quite unpredictably, because experiments in channels adjacent to those used for NAA require an adjustment of the reactor operation parameters and/or active core configuration. For frequent monitoring of the neutron flux parameters the bare multi-monitor method is very convenient. The well-known Au-Zr tri-isotopic monitor set that provides a good tool for determining f and ? after long-time irradiation is not optimal in case of short-time irradiation because only a low activity of the 95Zr radionuclide is formed. Therefore, several elements forming radionuclides with suitable half-lives and Q0 and ?r parameters in a wide range of values were tested, namely 198Au, 56Mn, 88Rb, 128I, 139Ba, and 239U. As a result, an optimal mixture was selected consisting of Au, Mn, and Rb to form a well suited monitor set for irradiation at a thermal neutron fluence rate of 3×1017 m-2 s-1. The procedure of short-time INAA with the new monitor set for k0 standardization was successfully validated using the synthetic reference material SMELS 1 and several matrix reference materials (RMs) representing matrices of sample types frequently analyzed in our laboratory. The results were obtained using the Kayzero for Windows program.

  4. Short time sports exercise boosts motor imagery patterns: implications of mental practice in rehabilitation programs

    PubMed Central

    Wriessnegger, Selina C.; Steyrl, David; Koschutnig, Karl; Müller-Putz, Gernot R.

    2014-01-01

    Motor imagery (MI) is a commonly used paradigm for the study of motor learning or cognitive aspects of action control. The rationale for using MI training to promote the relearning of motor function arises from research on the functional correlates that MI shares with the execution of physical movements. While most of the previous studies investigating MI were based on simple movements in the present study a more attractive mental practice was used to investigate cortical activation during MI. We measured cerebral responses with functional magnetic resonance imaging (fMRI) in twenty three healthy volunteers as they imagined playing soccer or tennis before and after a short physical sports exercise. Our results demonstrated that only 10 min of training are enough to boost MI patterns in motor related brain regions including premotor cortex and supplementary motor area (SMA) but also fronto-parietal and subcortical structures. This supports previous findings that MI has beneficial effects especially in combination with motor execution when used in motor rehabilitation or motor learning processes. We conclude that sports MI combined with an interactive game environment could be a promising additional tool in future rehabilitation programs aiming to improve upper or lower limb functions or support neuroplasticity. PMID:25071505

  5. Cretaceous-tertiary boundary event: Evidence for a short time scale

    SciTech Connect

    Gilmour, I.; Anders, E. )

    1989-02-01

    Three non-meteoritic trace elements (Sb, As and Zn) are strongly enriched at eleven K-T boundary sites, along with mainly or partly meteoritic elements (Ir, Ni, Cr, Fe and Co). The proportions (As, Sb, Zn/Ir) are remarkably constant over a {approx}100-fold range in concentration. This correlation persists in sub-layers of boundary clay and even extends to soot (from burned land biomass). Apparently, all the components, despite their diverse origins, became associated in a single, global component prior to deposition. No wholly satisfactory source is available for As, Sb and Zn: the trace element pattern in volcanic gases does not match that in K-T boundary clay, with ratios to Ir falling short by 1 to 2 orders of magnitude, terrestrial rocks do not reach high enough concentrations and (modern) ocean water contains too little Zn, but on balance, the latter source seems preferable--perhaps augmented by volatiles from the impact crater. Apparently, Ir-bearing ejecta and soot from forest fires coagulated in the stratosphere and then fell out together, sweeping out oceanic biomass and anoxically precipitating As, Sb and Zn. Significantly, the amounts of marine and land biomass at the K-T boundary correspond to about the steady-state global inventory (1 generation), and the amounts of As, Sb and Zn are also within a factor of {approx}5 of the global inventory. This is expected in a catastrophic but not a gradualist scenario.

  6. Short time sports exercise boosts motor imagery patterns: implications of mental practice in rehabilitation programs.

    PubMed

    Wriessnegger, Selina C; Steyrl, David; Koschutnig, Karl; Müller-Putz, Gernot R

    2014-01-01

    Motor imagery (MI) is a commonly used paradigm for the study of motor learning or cognitive aspects of action control. The rationale for using MI training to promote the relearning of motor function arises from research on the functional correlates that MI shares with the execution of physical movements. While most of the previous studies investigating MI were based on simple movements in the present study a more attractive mental practice was used to investigate cortical activation during MI. We measured cerebral responses with functional magnetic resonance imaging (fMRI) in twenty three healthy volunteers as they imagined playing soccer or tennis before and after a short physical sports exercise. Our results demonstrated that only 10 min of training are enough to boost MI patterns in motor related brain regions including premotor cortex and supplementary motor area (SMA) but also fronto-parietal and subcortical structures. This supports previous findings that MI has beneficial effects especially in combination with motor execution when used in motor rehabilitation or motor learning processes. We conclude that sports MI combined with an interactive game environment could be a promising additional tool in future rehabilitation programs aiming to improve upper or lower limb functions or support neuroplasticity. PMID:25071505

  7. Pulsatile microvascular blood flow imaging by short-time Fourier transform analysis of ultrafast laser holographic interferometry

    E-print Network

    Puyo, L; Rancillac, A; Simonutti, M; Paques, M; Sahel, J A; Fink, M; Atlan, M

    2015-01-01

    We report on wide-field imaging of pulsatile microvascular blood flow in the exposed cerebral cortex of a mouse by holographic interferometry. We recorded interferograms of laser light backscattered by the tissue, beating against an off-axis reference beam with a 50 kHz framerate camera. Videos of local Doppler contrasts were rendered numerically by Fresnel transformation and short-time Fourier transform analysis. This approach enabled instantaneous imaging of pulsatile blood flow contrasts in superficial blood vessels over 256 x 256 pixels with a spatial resolution of 10 microns and a temporal resolution of 20 ms.

  8. Time-resolved observation of fast domain-walls driven by vertical spin currents in short tracks

    SciTech Connect

    Sampaio, Joao; Lequeux, Steven; Chanthbouala, Andre; Cros, Vincent; Grollier, Julie; Matsumoto, Rie; Yakushiji, Kay; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji; Nishimura, Kazumasa; Nagamine, Yoshinori; Maehara, Hiroki; Tsunekawa, Koji

    2013-12-09

    We present time-resolved measurements of the displacement of magnetic domain-walls (DWs) driven by vertical spin-polarized currents in track-shaped magnetic tunnel junctions. In these structures, we observe very high DW velocities (600?m/s) at current densities below 10{sup 7}?A/cm{sup 2}. We show that the efficient spin-transfer torque combined with a short propagation distance allows avoiding the Walker breakdown process and achieving deterministic, reversible, and fast (?1?ns) DW-mediated switching of magnetic tunnel junction elements, which is of great interest for the implementation of fast DW-based spintronic devices.

  9. Short contact time direct coal liquefaction using a novel batch reactor. Progress report, January 1, 1994--May 15, 1994

    SciTech Connect

    Klein, M.T.; Calkins, W.H.

    1994-05-31

    The objective for this research is to optimize the design and operation of the bench scale batch reactor (SCTBR) for coal liquefaction at short contact times (0.01 to 10 minutes or longer). This reactor is simple enough and low enough in cost to serve as a suitable replacement for the traditional tubing-bomb reactors for many coal liquefaction and other high-pressure, high-temperature reaction studies. The liquefaction of selected Argonne Premium coals and the role of organic oxygen components of the coal and their reaction pathways at very low conversions are being investigated.

  10. Short contact time direct coal liquefaction using a novel batch reactor. Progress report, May 16, 1994--September 15, 1994

    SciTech Connect

    Klein, M.T.; Calkins, W.H.

    1994-09-30

    The objective of this research is to optimize the design and operation of the bench scale batch reactor (SCTBR) for coal liquefaction at short contact times (0.01 to 10 minutes or longer). This reactor is simple enough and low enough in cost to serve as a suitable replacement for the traditional tubing-bomb reactors for many coal liquefaction and other high-pressure, high-temperature reaction studies. The liquefaction of selected Argonne Premium coals and the role of organic oxygen components of the coal and their reaction pathways at very low conversions are being investigated.

  11. Spatial and Time Coincidence Detection of the Decay Chain of Short-Lived Radioactive Nuclei

    SciTech Connect

    Granja, Carlos; Jakubek, Jan; Platkevic, Michal; Pospisil, Stanislav

    2010-08-04

    The quantum counting position sensitive pixel detector Timepix with per-pixel energy and time resolution enables to detect radioactive ions and register the consecutive decay chain by simultaneous position-and time-correlation. This spatial and timing coincidence technique in the same sensor is demonstrated by the registration of the decay chain {sup 8}He{yields}{sup {beta} 8}Li and {sup 8}Li{yields}{sup {beta}-} {sup 8}Be{yields}{alpha}+{alpha} and by the measurement of the {beta} decay half-lives. Radioactive ions, selectively obtained from the Lohengrin fission fragment spectrometer installed at the High Flux Reactor of the ILL Grenoble, are delivered to the Timepix silicon sensor where decays of the implanted ions and daughter nuclei are registered and visualized. We measure decay lifetimes in the range {>=}{mu}s with precision limited just by counting statistics.

  12. [Evaluation of short-time premedication with d-chlorpheniramine maleate injection for paclitaxel-induced hypersensitivity reaction].

    PubMed

    Harada, Tomohiko; Doi, Masakazu; Yamada, Yasuhiko; Akase, Tomohide

    2008-08-01

    Paclitaxel(referred to hereinafter as PTX )is used in ovarian cancer, non-small cell lung cancer, breast cancer, gastric cancer, and endometrial cancer with positive treatment result reports. However, severe allergic reactions such as decreases in blood pressure and impaired breathing occur with relatively high frequency. For the prevention of such allergic reactions, administration of a premedication composed of the three components, dexamethasone sodium phosphate injection, diphenhydramine hydrochloride tablet, and ranitidine hydrochloride injection solution(or injectable famodine), is advised in the appended documentation. Administration is difficult because, among these three components, only diphenhydramine hydrochloride is administered orally and thus must be provided through the internal medicine department. Particularly when this combined dosage is administered as outpatient chemotherapy, the doctor must prescribe diphenhydramine hydrochloride tablets, and the patient must not forget to bring them on the day in which chemotherapy is administered. Also, checks by the medical staff such as pharmacists and nurses are required, complicating the administration of this therapy further. Taking this situation into consideration, our hospital uses a short-time premedication method wherein d-Chlorpheniramine Maleate injections are substituted for diphenhydramine hydrochloride tablets, and the time required for premedication is reduced to 15 minutes. This study investigated the allergic reaction ratio to consider the safety and usefulness of the short-time premedication method used at our hospital. The chemotherapy regimens conducted for the subject patients were 9 cases of PTX+CBDCA, 6 cases of biweekly- PTX, and 5 cases of weekly-PTX. A total of 67 PTX injections were given, 15 of them being first-time administrations. The ratio of allergic/hypersensitivity reactions was 10.0%(2 cases in 20). The short-time premedication method using d-Chlorpheniramine Maleate injections did not display a significant difference from the conventional method used for prevention of allergic and hypersensitivity reactions. Also, since this method of medication proves useful for is easy for the patient, reduces treatment time, is safe, economical, and helps reduce the workload of doctors, pharmacists, and nurses. PMID:18701846

  13. Performance impact on nuclear thermal propulsion of piloted Mars missions with short transit times

    NASA Technical Reports Server (NTRS)

    Wickenheiser, T. J.; Gessner, K. S.; Alexander, S. W.

    1991-01-01

    The requirements of nuclear thermal propulsion (NTP) are examined with respect to a specific mission scenario derived from Stafford Committee recommendations. The recommended mission scenario is a split/sprint opposition mission which includes a piloted vehicle and a cargo vehicle, and the baseline mission is developed from a reference trajectory. Key mision parameters are developed from the baseline mission, including engine-thrust levels, mission opportunity, and engine burn-time requirements. The impact of engine failure is also considered in terms of burn-time requirements, and other mission-performance issues considered include propulsion-technology assumptions, triple-perigee earth-departure burns, and Mars parking-orbit selection. The engine requirements call for a 50-75-klb engine-thrust level, maximum single burn time of 0.6 hours, and a maximum total-mission burn time of 1.7 hours. For a crew of 6, a 475-day total-mission trip with a 90-day stay at Mars is possible.

  14. Transcription factor target prediction using multiple short expression time series from Arabidopsis thaliana

    PubMed Central

    Redestig, Henning; Weicht, Daniel; Selbig, Joachim; Hannah, Matthew A

    2007-01-01

    Background The central role of transcription factors (TFs) in higher eukaryotes has led to much interest in deciphering transcriptional regulatory interactions. Even in the best case, experimental identification of TF target genes is error prone, and has been shown to be improved by considering additional forms of evidence such as expression data. Previous expression based methods have not explicitly tried to associate TFs with their targets and therefore largely ignored the treatment specific and time dependent nature of transcription regulation. Results In this study we introduce CERMT, Covariance based Extraction of Regulatory targets using Multiple Time series. Using simulated and real data we show that using multiple expression time series, selecting treatments in which the TF responds, allowing time shifts between TFs and their targets and using covariance to identify highly responding genes appear to be a good strategy. We applied our method to published TF – target gene relationships determined using expression profiling on TF mutants and show that in most cases we obtain significant target gene enrichment and in half of the cases this is sufficient to deliver a usable list of high-confidence target genes. Conclusion CERMT could be immediately useful in refining possible target genes of candidate TFs using publicly available data, particularly for organisms lacking comprehensive TF binding data. In the future, we believe its incorporation with other forms of evidence may improve integrative genome-wide predictions of transcriptional networks. PMID:18021423

  15. For more information, please refer to: http://mobility.tamu.edu/mip/strategies.php. Time: Short

    E-print Network

    For more information, please refer to: http://mobility.tamu.edu/mip/strategies.php. Cost: Time their workplace flexibility program in 1993. The company encourages its employees to use different flexible schedule options to fit their individual needs. The City of Houston's mayor initiated Flex in City program

  16. Metabolic syndrome increases oxidative stress but does not influence disability and short-time outcome in acute ischemic stroke patients.

    PubMed

    Simão, Andrea Name Colado; Lehmann, Marcio Francisco; Alfieri, Daniela Frizon; Meloni, Milena Zardetto; Flauzino, Tamires; Scavuzzi, Bruna Miglioranza; de Oliveira, Sayonara Rangel; Lozovoy, Marcell Alysson Batisti; Dichi, Isaias; Reiche, Edna Maria Vissoci

    2015-12-01

    Oxidative stress has been implicated in the pathophysiology of cardiovascular disease and MetS and it may be one of molecular mechanisms involved in stroke. The aims of the present study were to verify differences in oxidative stress markers in acute ischemic stroke patients with and without MetS and to verify whether MetS influences disability and short time outcome of the patients. 148 patients with acute ischemic stroke were divided in two groups: with MetS (n?=?92) and without MetS (n?=?56). The modified Rankin Scale (mRS) was used for measuring the functional disability after 3-month follow-up. The study assessed the metabolic profile and oxidative stress markers. Stroke patients with MetS had higher levels of lipid hydroperoxides (p?short-come outcome did not differ after 3 months in both groups. In conclusion, an increase in oxidative stress markers was shown in acute ischemic stroke patients with MetS and this elevation seems to be involved mainly with changes in lipid profile, but the presence of MetS did not influence short-time disability and survival of the acute ischemic stroke patients. PMID:26342606

  17. Short communication: Timing of first milking affects serotonin (5-HT) concentrations.

    PubMed

    Laporta, J; Gross, J J; Crenshaw, T D; Bruckmaier, R M; Hernandez, L L

    2014-05-01

    Hormonal signals differentially regulate the timing of parturition, as well lactogenesis and, potentially, colostrum formation in the mammary gland. Non-neuronal serotonin (5-HT) is a homeostatic regulator of the mammary gland. In the current study, we manipulated the timing of first milking to investigate its effects on serum 5-HT and calcium concentrations in the maternal and calf circulation, as well as in colostrum. Twenty-three cows were randomly assigned to a control (CON; n=10) group, milked for the first time at 4h postcalving, or a treatment (TRT; n=13) group, milked for the first time approximately 1 d before calving in addition to 4h postcalving. Maternal blood samples were collected for 4 d precalving, 3 times daily, and 1 blood sample was taken 4h postcalving. Calf blood samples were collected 4 (before first colostrum feeding) and 12h after birth, and at 3 wk of age. Calves from both treatments were fed colostrum from their respective mothers. Serum 5-HT concentrations were greater in CON cows and decreased significantly in TRT cows after milking was initiated precalving (951 vs. 524 ± 111 ng/mL, respectively). Cow serum calcium concentrations were affected by time, beginning to decrease 1 d precalving until 4h postcalving, but this drop in serum calcium was more pronounced in TRT cows. Serum 5-HT and calcium concentrations were negatively correlated (r=-0.57) for the CON cows and positively correlated (r=0.6) for the TRT cows. Maternal calcium and 5-HT decreased similarly due to precalving milking. Calcium and 5-HT concentrations were greater in colostrum collected from TRT cows milked precalving. Overall, calves had higher circulating 5-HT concentrations than cows, and calves born to TRT cows had increased 5-HT concentrations compared with the CON. Precalving milking could affect 5-HT synthesis within the mammary gland and therefore affect maternal 5-HT and calcium concentrations. Further research is needed in ruminants to assess the extent of 5-HT placental transfer, its role on pre- and postnatal development of the calf, the importance of its presence in colostrum, and potential long-term effects on calf health. PMID:24612806

  18. Does Occupational Exposure of Shahid Dastghieb International Airport Workers to Radiofrequency Radiation Affect Their Short Term Memory and Reaction Time?

    PubMed Central

    Jarideh, S.; Taeb, S.; Pishva, S. M.; Haghani, M.; Sina, S.; Mortazavi, S. A. R.; Hosseini, M. A.; Nematollahi, S.; Shokrpour, N.; Hassan Shahi, M.; Mortazavi, S. M. J.

    2015-01-01

    Background Airport workers are continuously exposed to different levels of radiofrequency microwave (RF/MW) radiation emitted by radar equipments. Radars are extensively used in military and aviation industries. Over the past several years, our lab has focused on the health effects of exposure to different sources of electromagnetic fields such as cellular phones, mobile base stations, mobile phone jammers, laptop computers, radars, dentistry cavitrons and MRI. The main goal of this study was to investigate if occupational exposure of Shahid Dastghieb international airport workers to radiofrequency radiation affects their short term memory and reaction time. Methods Thirty two airport workers involved in duties at control and approach tower (21 males and 11 females), with the age range of 27-67 years old (mean age of 37.38), participated voluntary in this study. On the other hand, 29 workers (13 males, and 16 females) whose offices were in the city with no exposure history to radar systems were also participated in this study as the control group. The employees’ reaction time and short term memory were analyzed using a standard visual reaction time (VRT) test software and the modified Wechsler memory scale test, respectively. Results The mean± SD values for the reaction times of the airport employees (N=32) and the control group (N=29) were 0.45±0.12 sec and 0.46±0.17 sec, respectively.  Moreover, in the four subset tests; i.e. paired words, forward digit span, backward digit span and word recognition, the following points were obtained for the airport employees and the control group, respectively: (i) pair words test: 28.00±13.13 and 32.07±11.65, (ii) forward digit span: 8.38±1.40 and 9.03±1.32, (iii) backward digit span: 5.54±1.87 and 6.31±1.46, and (iv) word recognition: 5.73±2.36 and 6.50±1.93. These differences were not statistically significant. Conclusion The occupational exposure of the employees to the RF radiation in Shahid Dastghieb international airport does not have any significant detrimental effect on their reaction time as well as short term memory. PMID:26396970

  19. Short time variability of solar corona during recent solar cycle minimum

    NASA Astrophysics Data System (ADS)

    Siarkowski, Marek; Gryciuk, Magdalena; Gburek, Szymon; Sylwester, Janusz; Sylwester, Barbara; Kepa, Anna; Buczkowska, Agnieszka; Kowalinski, Miroslaw

    Sphinx is the X-ray spectrophotometer designed to measure X-ray emission from the Sun in the energy range between 0.8 keV and 15 keV. The instrument is placed onboard Russian KORONAS-PHOTON satellite launched on January 30, 2009. In this paper we present the observations of coronal emission obtained between March-April and August-September 2009, i.e. the times towards the end of the last, very prolonged and deep minimum of solar activity. Prompt analysis of SphinX spectra reveal the variability of the average coronal plasma charac-teristics like the temperature and emission measure. These data are used to compare SphinX and GOES measurements, for selected times. Examples of many sub/microflare events with maxima of the X-ray flux, observed much below the GOES sensitivity threshold level will be presented.

  20. A Short Essay on Quantum Black Holes and Underlying Noncommutative Quantized Space-Time

    E-print Network

    Tanaka, Sho

    2015-01-01

    In our preceding paper, "Where does Black- Hole Entropy Lie? - Some Remarks on Area-Entropy Law, Holographic Principle and Noncommutative Space-Time" (Eur. Phys. J. Plus (2014) {\\bf 129}: 11), we emphasized the importance of underlying noncommutative geometry or Lorenz-covariant quantized space-time towards ultimate theory of quantum gravity and Planck scale physics. We focused there our attention on the {\\it statistical} and {\\it substantial} understanding of Bekenstein-Hawking's Area-Entropy Law of black holes on the bases of Kinematical Holographic Relation [KHR] which holds in Yang's quantized space-time. [KHR] really plays an important role in our approach in place of the familiar hypothesis, so called Holographic Principle. In the present paper, we find out a unified form of [KHR] applicable to the whole region ranging from macroscopic to microscopic scales of black holes in spatial dimension $ d=3.$ We notice the existence and behavior of two kinds of temperatures of black holes, $T_{H.R.}$ and $T_S,$ ...

  1. Short-Term Dispersal Response of an Endangered Australian Lizard Varies with Time of Year

    PubMed Central

    Ebrahimi, Mehregan; Bull, C. Michael

    2014-01-01

    Dispersal is an important component in the demography of animal populations. Many animals show seasonal changes in their tendency to disperse, reflecting changes in resource availability, mating opportunities, or in population age structure at the time when new offspring enter the population. Understanding when and why dispersal occurs can be important for the management of endangered species. The pygmy bluetongue lizard is an endangered Australian species that occupies and defends single burrow refuges for extended periods of time, rarely moving far from the burrow entrance. However, previous pitfall trapping data have suggested movement of adult males in spring and of juveniles in autumn of each year. In the current study we compared behaviours of adult lizards each month, over the spring-summer activity period over two consecutive field seasons, to provide deeper understanding of the seasonal dispersal pattern. We released adult pygmy bluetongue lizards into a central area, provided with artificial burrows, within large enclosures, and monitored the behaviour and movements of the released lizards over a four day period. There was a consistent decline in time spent basking, amount of movement around burrow entrances, and rates of dispersal from the central release area from early spring to late summer. Results could be relevant to understanding and managing natural populations and for any translocation attempts of this endangered lizard species. PMID:25147949

  2. Five-Kilometers Time Trial: Preliminary Validation of a Short Test for Cycling Performance Evaluation

    PubMed Central

    Dantas, Jose Luiz; Pereira, Gleber; Nakamura, Fabio Yuzo

    2015-01-01

    Background: The five-kilometer time trial (TT5km) has been used to assess aerobic endurance performance without further investigation of its validity. Objectives: This study aimed to perform a preliminary validation of the TT5km to rank well-trained cyclists based on aerobic endurance fitness and assess changes of the aerobic endurance performance. Materials and Methods: After the incremental test, 20 cyclists (age = 31.3 ± 7.9 years; body mass index = 22.7 ± 1.5 kg/m2; maximal aerobic power = 360.5 ± 49.5 W) performed the TT5km twice, collecting performance (time to complete, absolute and relative power output, average speed) and physiological responses (heart rate and electromyography activity). The validation criteria were pacing strategy, absolute and relative reliability, validity, and sensitivity. Sensitivity index was obtained from the ratio between the smallest worthwhile change and typical error. Results: The TT5km showed high absolute (coefficient of variation < 3%) and relative (intraclass coefficient correlation > 0.95) reliability of performance variables, whereas it presented low reliability of physiological responses. The TT5km performance variables were highly correlated with the aerobic endurance indices obtained from incremental test (r > 0.70). These variables showed adequate sensitivity index (> 1). Conclusions: TT5km is a valid test to rank the aerobic endurance fitness of well-trained cyclists and to differentiate changes on aerobic endurance performance. Coaches can detect performance changes through either absolute (± 17.7 W) or relative power output (± 0.3 W.kg-1), the time to complete the test (± 13.4 s) and the average speed (± 1.0 km.h-1). Furthermore, TT5km performance can also be used to rank the athletes according to their aerobic endurance fitness. PMID:26448846

  3. Short time-scale frequency and amplitude variations in the pulsations of an roAp star: HD 217522

    NASA Astrophysics Data System (ADS)

    Medupe, R.; Kurtz, D. W.; Elkin, V. G.; Mguda, Z.; Mathys, G.

    2015-01-01

    Photometric observations of HD 217522 in 1981 revealed only one pulsation frequency ?1 = 1.215 29 mHz. Subsequent observations in 1989 showed the presence of an additional frequency ?2 = 2.0174 mHz. New observations in 2008 confirm the presence of the mode with ?2 = 2.0174 mHz. Examination of the 1989 data shows amplitude modulation over a time-scale of the order of a day, much shorter than what has been observed in other rapidly oscillating Ap (roAp) stars. High spectral and time resolution data obtained using the Very Large Telescope in 2008 confirm the presence of ?2 and short-term modulations in the radial velocity amplitudes of rare earth elements. This suggests growth and decay times shorter than a day, more typical of solar-like oscillations. The driving mechanism of roAp stars and the Sun are different, and the growth and decay seen in the Sun are due to stochastic nature of the driving mechanism. The driving mechanism in roAp stars usually leads to mode stability on a longer time-scale than in the Sun. We interpret the reported change in ?1 between the 1982 and 1989 data as part of the general frequency variability observed in this star on many time-scales.

  4. Time Dependence of Material Properties of Polyethylene Glycol Hydrogels Chain Extended with Short Hydroxy Acid Segments

    PubMed Central

    Barati, Danial; Moeinzadeh, Seyedsina; Karaman, Ozan; Jabbari, Esmaiel

    2014-01-01

    The objective of this work was to investigate the effect of chemical composition and segment number (n) on gelation, stiffness, and degradation of hydroxy acid-chain-extended star polyethylene glycol acrylate (SPEXA) gels. The hydroxy acids included glycolide (G,), L-lactide (L), p-dioxanone (D) and -caprolactone (C). Chain-extension generated water soluble macromers with faster gelation rates, lower sol fractions, higher compressive moduli, and a wide-ranging degradation times when crosslinked into a hydrogel. SPEGA gels with the highest fraction of inter-molecular crosslinks had the most increase in compressive modulus with n whereas SPELA and SPECA had the lowest increase in modulus. SPEXA gels exhibited a wide range of degradation times from a few days for SPEGA to a few weeks for SPELA, a few months for SPEDA, and many months for SPECA. Marrow stromal cells and endothelial progenitor cells had the highest expression of vasculogenic markers when co-encapsulated in the faster degrading SPELA gel. PMID:25267858

  5. High Photoresponsivity and Short Photoresponse Times in Few-Layered WSe2 Transistors.

    PubMed

    Pradhan, Nihar R; Ludwig, Jonathan; Lu, Zhengguang; Rhodes, Daniel; Bishop, Michael M; Thirunavukkuarasu, Komalavalli; McGill, Stephen A; Smirnov, Dmitry; Balicas, Luis

    2015-06-10

    Here, we report the photoconducting response of field-effect transistors based on three atomic layers of chemical vapor transport grown WSe2 crystals mechanically exfoliated onto SiO2. We find that trilayered WSe2 field-effect transistors, built with the simplest possible architecture, can display high hole mobilities ranging from 350 cm(2)/(V s) at room temperature (saturating at a value of ?500 cm(2)/(V s) below 50 K) displaying a strong photocurrent response, which leads to exceptionally high photoresponsivities up to 7 A/W under white light illumination of the entire channel for power densities p < 10(2) W/m(2). Under a fixed wavelength of ? = 532 nm and a laser spot size smaller than the conducting channel area, we extract photoresponsitivities approaching 100 mA/W with concomitantly high external quantum efficiencies up to ?40% at room temperature. These values surpass values recently reported from more complex architectures, such as graphene and transition metal dichalcogenides based heterostructures. Also, trilayered WSe2 phototransistors display photoresponse times on the order of 10 ?s. Our results indicate that the addition of a few atomic layers considerably decreases the photoresponse times, probably by minimizing the interaction with the substrates, while maintaining a very high photoresponsivity. PMID:25988364

  6. Anodic Polarization Curves Revisited

    ERIC Educational Resources Information Center

    Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin

    2013-01-01

    An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…

  7. Introduction: Active Vision Revisited

    E-print Network

    Daume III, Hal

    Introduction: Active Vision Revisited Y. Aloimonos. University of Maryland What is, is identical results on Active Vision [2, 5], researchers are beginning to realize that perception (and intelligence that it performs. This viewpoint, known as Purposive, Qualitative or Animate Vision, is the natural evolution

  8. Revisiting Curriculum Potential

    ERIC Educational Resources Information Center

    Deng, Zongyi

    2011-01-01

    This article analyzes the notion of curriculum potential by revisiting the ideas of Miriam Ben-Peretz and Joseph Schwab. Invoking the German "Didaktik" tradition and by way of a curriculum-making framework, the paper argues that interpreting curriculum materials for curriculum potential requires a careful analysis and unpacking of the meanings and…

  9. Colloquial Hebrew Imperatives Revisited

    ERIC Educational Resources Information Center

    Bolozky, Shmuel

    2009-01-01

    In revisiting Bolozky's [Bolozky, Shmuel, 1979. "On the new imperative in colloquial Hebrew." "Hebrew Annual Review" 3, 17-24] and Bat-El's [Bat-El, Outi, 2002. "True truncation in colloquial Hebrew imperatives." "Language" 78(4), 651-683] analyses of colloquial Hebrew imperatives, the article argues for restricting Imperative Truncation to the…

  10. A Hydrostatic Paradox Revisited

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2012-01-01

    This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

  11. Revisiting Bioaccumulation Criteria

    EPA Science Inventory

    The objective of workgroup 5 was to revisit the B(ioaccumulation) criteria that are currently being used to identify POPs under the Stockholm Convention and PBTs under CEPA, TSCA, REACh and other programs. Despite the lack of a recognized definition for a B substance, we defined ...

  12. Concept Image Revisited

    ERIC Educational Resources Information Center

    Bingolbali, Erhan; Monaghan, John

    2008-01-01

    Concept image and concept definition is an important construct in mathematics education. Its use, however, has been limited to cognitive studies. This article revisits concept image in the context of research on undergraduate students' understanding of the derivative which regards the context of learning as paramount. The literature, mainly on…

  13. Short time existence and uniqueness in Hölder spaces for the 2D dynamics of dislocation densities

    E-print Network

    Ahmad El Hajj

    2009-03-09

    In this paper, we study the model of Groma and Balogh describing the dynamics of dislocation densities. This is a two-dimensional model where the dislocation densities satisfy a system of two transport equations. The velocity vector field is the shear stress in the material solving the equations of elasticity. This shear stress can be related to Riesz transforms of the dislocation densities. Basing on some commutator estimates type, we show thatthis model has a unique local-in-time solution corresponding to any initial datum in the space $C^r(\\R^2)\\cap L^p(\\R^2)$ for $r>1$ and $1

  14. Short treatment time and excellent treatment outcome in accelerated hyperfractionated radiotherapy for T1 glottic cancer

    PubMed Central

    Tamaki, Yukihisa; Hieda, Yoko; Yoshida, Rika; Yoshizako, Takeshi; Fuchiwaki, Takafumi; Aoi, Noriaki; Sekihara, Kazumasa; Kitajima, Kazuhiro; Kawauchi, Hideyuki; Kitagaki, Hajime; Sasaki, Ryohei; Inomata, Taisuke

    2015-01-01

    ABSTRACT Accelerated hyperfractionated radiotherapy was performed as treatment for patients with T1 glottic cancer, and its utility was evaluated based on treatment outcomes and adverse effects. Fifty-eight men who had undergone radiotherapy were retrospectively reviewed. Tumor classification was Tis in 4 patients, T1a in 38, and T1b in 16. Histological examination revealed squamous cell carcinoma in 55 patients. Travel time from home to hospital was 0–1 hour for 24 patients, 1–2 hours for 9, and >2 hours for 25. Laser vaporization was performed prior to radiotherapy in 38 patients, and 19 patients received concurrent chemotherapy with an agent such as S-1. Patients were irradiated twice daily using an irradiation container. Most patients received a dose of 1.5 Gy/fraction up to a total of 60 Gy. The median overall treatment time was 30 days, with a median observation period of 59.6 months. A complete response was observed in all patients. The 5-year overall survival, disease-free survival, and local control rates were 97.2%, 93.2%, and 97.8%, respectively. Although grade 3 pharyngeal mucositis was observed in 2 patients, there were no other grade 3 or higher acute adverse events. As late toxicity, grade 2 laryngeal edema and grade 1 laryngeal hemorrhage were observed in 1 patient each, but no serious events such as laryngeal necrosis or laryngeal stenosis were observed. In conclusion, this treatment method brings excellent outcome and will substantially reduce the treatment duration among patients who need to stay at nearby hotels while undergoing treatment at hospitals in rural areas. PMID:26663937

  15. Raman Scattering at Resonant or Near-Resonant Conditions: A Generalized Short-Time Approximation

    NASA Astrophysics Data System (ADS)

    Mohammed, Abdelsalam; Sun, Yu-Ping; Miao, Quan; Ågren, Hans; Gel'mukhanov, Faris

    2012-02-01

    We investigate the dynamics of resonant Raman scattering in the course of the frequency detuning. The dephasing in the time domain makes the scattering fast when the photon energy is tuned from the absorption resonance. This makes frequency detuning to act as a camera shutter with a regulated scattering duration and provides a practical tool of controlling the scattering time in ordinary stationary measurements. The theory is applied to resonant Raman spectra of a couple of few-mode model systems and to trans-1,3,5-hexatriene and guanine-cytosine (G-C) Watson-Crick base pairs (DNA) molecules. Besides some particular physical effects, the regime of fast scattering leads to a simplification of the spectrum as well as to the scattering theory itself. Strong overtones appear in the Raman spectra when the photon frequency is tuned in the resonant region, while in the mode of fast scattering, the overtones are gradually quenched when the photon frequency is tuned more than one vibrational quantum below the first absorption resonance. The detuning from the resonant region thus leads to a strong purification of the Raman spectrum from the contamination by higher overtones and soft modes and purifies the spectrum also in terms of avoidance of dissociation and interfering fluorescence decay of the resonant state. This makes frequency detuning a very useful practical tool in the analysis of the resonant Raman spectra of complex systems and considerably improves the prospects for using the Raman effect for detection of foreign substances at ultra-low concentrations.

  16. Control of insects and mites in grain using a high temperature/short time (HTST) technique.

    PubMed

    Mourier; Poulsen

    2000-07-01

    Wheat infested with grain mites (Acari) and Sitophilus granarius, and maize infested with Prostephanus truncatus, were exposed to hot air in a CIMBRIA HTST Microline toaster((R)). Inlet temperatures of the hot air were in the range of 150-750 degrees C decreasing to outlet temperatures in the range of 100-300 degrees C during the exposure period. A rotating drum, connected to a natural-gas burner was fed with grain which was in constant movement along the drum and thereby mixed thoroughly during the process. The capacity of the toaster was 1000 kg per hour.Complete control of grain mites and adult S. granarius in wheat was obtained with an inlet temperature of 300-350 degrees C and an average residence time in the drum of 6 s. More than 99% mortality was obtained for all stages of S. granarius with an inlet temperature of 300-350 degrees C and an average exposure period of 40 s. For control of P. truncatus in maize, an inlet temperature of 700 degrees C resulted in a complete disinfestation when the exposure time was 19 s.The reduction in grain moisture content was 0.5-1% at treatments giving 100% control. Germination tests indicate that it is possible to choose a combination of inlet temperatures and exposure periods which effectively kills mites and insects in small grains, without harming the functional properties of the grain.Economy of the method was considered to be competitive with fumigation using phosphine. PMID:10758269

  17. The effect of short-time microwave exposures on Listeria monocytogenes inoculated onto chicken meat portions

    PubMed Central

    Zeinali, Tayebeh; Jamshidi, Abdollah; Khanzadi, Saeid; Azizzadeh, Mohammad

    2015-01-01

    Listeria monocytogenes can be found throughout the environment and in many foods. It is associated primarily with meat and animal products. Listeria monocytogenes has become increasingly important as a food-borne pathogen. The aim of this study was to evaluate the effect of microwave (MW) treatment of chicken meat samples which were inoculated with L. monocytogenes. Drumettes of broiler carcasses were soaked in fully growth of L. monocytogenes in Brain-Heart Infusion broth. The swab samples were taken from the inoculated samples, after various times of radiation (10, 20, 30, 40, 50, 60, 70 and 80 sec), using a domestic MW oven at full power. Following exposures, viable counts and surface temperature measurements were performed. The bacterial counts were performed on Oxford agar. The results indicated that equal or longer than 60 sec exposures of chicken portions to MW heating which enhances the median surface temperature more than 74 ?C could eliminate the superficial contamination of chicken meat with L. monocytogenes. Statistical analysis showed samples with equal or longer than 60 sec exposures to MW heating had significant decrease in population of inoculated bacteria compared with positive control group (p < 0.05). Pearson correlation showed a significant correlation between the bacterial population and temperature of samples due to MW exposure (p < 0.001, r = – 0.879 and r2 = 0.773). PMID:26261715

  18. Multicolour time series photometry of four short-period weak-lined T Tauri stars

    NASA Astrophysics Data System (ADS)

    Koen, C.

    2015-05-01

    The paper describes continuous photometric monitoring of four pre-main-sequence stars, probable members of young stellar associations. Measurements, covering at least four nights per star, were obtained by cycling through several filters. The data could be used to choose between aliases of rotation periods quoted in the literature. As expected, the amplitudes of sinusoidal variations decline with increasing wavelength, mildly enough to indicate the presence of coolspots on the stellar surfaces. Variability amplitudes can dwindle from a 0.1 mag level to virtually zero on a time-scale of one or two days. A flare observed in CD-36 3202 is discussed in some detail, and a useful mathematical model for its shape is introduced. It is demonstrated that accurate colour indices (? < 5-6 mmag, typically) can be derived from the photometry. The magnitude variations as measured through different filters are linearly related. This is exploited to calculate spot temperatures (800-1150 K below photospheric for the different stars) and the ranges of variation of the spot filling factors (roughly 10-20 per cent). The available All Sky Automated Survey measurements of the stars are analysed, and it is concluded that there is good evidence for differential rotation in all four stars.

  19. The effect of short-time microwave exposures on Listeria monocytogenes inoculated onto chicken meat portions.

    PubMed

    Zeinali, Tayebeh; Jamshidi, Abdollah; Khanzadi, Saeid; Azizzadeh, Mohammad

    2015-01-01

    Listeria monocytogenes can be found throughout the environment and in many foods. It is associated primarily with meat and animal products. Listeria monocytogenes has become increasingly important as a food-borne pathogen. The aim of this study was to evaluate the effect of microwave (MW) treatment of chicken meat samples which were inoculated with L. monocytogenes. Drumettes of broiler carcasses were soaked in fully growth of L. monocytogenes in Brain-Heart Infusion broth. The swab samples were taken from the inoculated samples, after various times of radiation (10, 20, 30, 40, 50, 60, 70 and 80 sec), using a domestic MW oven at full power. Following exposures, viable counts and surface temperature measurements were performed. The bacterial counts were performed on Oxford agar. The results indicated that equal or longer than 60 sec exposures of chicken portions to MW heating which enhances the median surface temperature more than 74 ?C could eliminate the superficial contamination of chicken meat with L. monocytogenes. Statistical analysis showed samples with equal or longer than 60 sec exposures to MW heating had significant decrease in population of inoculated bacteria compared with positive control group (p < 0.05). Pearson correlation showed a significant correlation between the bacterial population and temperature of samples due to MW exposure (p < 0.001, r = - 0.879 and r (2) = 0.773). PMID:26261715

  20. Timing Rhythms: Perceived Duration Increases with a Predictable Temporal Structure of Short Interval Fillers

    PubMed Central

    Horr, Ninja K.; Di Luca, Massimiliano

    2015-01-01

    Variations in the temporal structure of an interval can lead to remarkable differences in perceived duration. For example, it has previously been shown that isochronous intervals, that is, intervals filled with temporally regular stimuli, are perceived to last longer than intervals left empty or filled with randomly timed stimuli. Characterizing the extent of such distortions is crucial to understanding how duration perception works. One account to explain effects of temporal structure is a non-linear accumulator-counter mechanism reset at the beginning of every subinterval. An alternative explanation based on entrainment to regular stimulation posits that the neural response to each filler stimulus in an isochronous sequence is amplified and a higher neural response may lead to an overestimation of duration. If entrainment is the key that generates response amplification and the distortions in perceived duration, then any form of predictability in the temporal structure of interval fillers should lead to the perception of an interval that lasts longer than a randomly filled one. The present experiments confirm that intervals filled with fully predictable rhythmically grouped stimuli lead to longer perceived duration than anisochronous intervals. No general over- or underestimation is registered for rhythmically grouped compared to isochronous intervals. However, we find that the number of stimuli in each group composing the rhythm also influences perceived duration. Implications of these findings for a non-linear clock model as well as a neural response magnitude account of perceived duration are discussed. PMID:26474047

  1. Photoinduced electron transfer and geminate recombination in liquids on short time scales: Experiments and theory

    NASA Astrophysics Data System (ADS)

    Goun, Alexei; Glusac, Ksenija; Fayer, M. D.

    2006-02-01

    The coupled processes of intermolecular photoinduced forward electron transfer and geminate recombination between the (hole) donor (Rhodamine 3B) and (hole) acceptors (N,N-dimethylaniline) are studied in three molecular liquids: acetonitrile, butyronitrile, and benzonitrile. Two color pump-probe experiments on time scales from ˜100fs to hundreds of picoseconds give information about the depletion of the donor excited state due to forward electron transfer and the survival kinetics of the radicals produced by forward electron transfer. The data are analyzed with a model presented previously that includes distance dependent forward and back electron transfer rates, donor and acceptor diffusion, solvent structure, and the hydrodynamic effect in a mean-field theory of through solvent electron transfer. The forward electron transfer is in the normal regime, and the Marcus equation for the distance dependence of the transfer rate is used. The forward electron transfer data for several concentrations in the three solvents are fitted to the theory with a single adjustable parameter, the electronic coupling matrix element Jf at contact. Within experimental error all concentrations in all three solvents are fitted with the same value of Jf. The geminate recombination (back transfer) is in the inverted region, and semiclassical treatment developed by Jortner [J. Chem. Phys. 64, 4860 (1976)] is used to describe the distance dependence of the back electron transfer. The data are fitted with the single adjustable parameter Jb. It is found that the value of Jb decreases as the solvent viscosity increases. Possible explanations are discussed.

  2. High protective, environmental friendly and short-time developed conversion coatings for aluminium alloys

    NASA Astrophysics Data System (ADS)

    Bethencourt, M.; Botana, F. J.; Cano, M. J.; Marcos, M.

    2002-04-01

    There are a variety of procedures, described in the bibliography, for producing conversion coatings using salts of lanthanide elements, and the coatings obtained by means of some of these procedures show acceptable levels of protection. Nevertheless, the principal limitation usually presented by these procedures is the excessively prolonged treatment times required to achieve such levels of protection. This therefore limits the applicability of these treatments on an industrial scale. Coatings on the alloy AA5083 obtained by using Ce(III) are characterised by having a mixed or heterogeneous nature, being composed of a layer of alumina covering the matrix, together with islands of cerium formed over the cathodic intermetallics that are present on the surface of the alloy. The results obtained indicate that, once these precipitates have been covered, the level of protection provided is conditional upon the thickness of the layer of alumina. In this study, a procedure is proposed for obtaining conversion coatings on the alloy AA5083 based on immersion in solutions of Ce(III) at temperatures higher than ambient. By this means, coatings can be produced in only a few minutes, and of such quality that salt fog tests of 168 h duration are successfully passed. Furthermore, studies conducted employing electrochemical techniques of linear polarisation indicate that the degree of protection provided by these coatings is several orders of magnitude superior to that achieved with other treatments.

  3. Flexible mate choice when mates are rare and time is short

    PubMed Central

    Tinghitella, Robin M; Weigel, Emily G; Head, Megan; Boughman, Janette W

    2013-01-01

    Female mate choice is much more dynamic than we once thought. Mating decisions depend on both intrinsic and extrinsic factors, and these two may interact with one another. In this study, we investigate how responses to the social mating environment (extrinsic) change as individuals age (intrinsic). We first conducted a field survey to examine the extent of natural variation in mate availability in a population of threespine sticklebacks. We then manipulated the sex ratio in the laboratory to determine the impact of variation in mate availability on sexual signaling, competition, and mating decisions that are made throughout life. Field surveys revealed within season heterogeneity in mate availability across breeding sites, providing evidence for the variation necessary for the evolution of plastic preferences. In our laboratory study, males from both female-biased and male-biased treatments invested most in sexual signaling late in life, although they competed most early in life. Females became more responsive to courtship over time, and those experiencing female-biased, but not male-biased sex ratios, relaxed their mating decisions late in life. Our results suggest that social experience and age interact to affect sexual signaling and female mating decisions. Flexible behavior could mediate the potentially negative effects of environmental change on population viability, allowing reproductive success even when preferred mates are rare. PMID:24101975

  4. On Short-Time Estimation of Vocal Tract Length from Formant Frequencies

    PubMed Central

    Lammert, Adam C.; Narayanan, Shrikanth S.

    2015-01-01

    Vocal tract length is highly variable across speakers and determines many aspects of the acoustic speech signal, making it an essential parameter to consider for explaining behavioral variability. A method for accurate estimation of vocal tract length from formant frequencies would afford normalization of interspeaker variability and facilitate acoustic comparisons across speakers. A framework for considering estimation methods is developed from the basic principles of vocal tract acoustics, and an estimation method is proposed that follows naturally from this framework. The proposed method is evaluated using acoustic characteristics of simulated vocal tracts ranging from 14 to 19 cm in length, as well as real-time magnetic resonance imaging data with synchronous audio from five speakers whose vocal tracts range from 14.5 to 18.0 cm in length. Evaluations show improvements in accuracy over previously proposed methods, with 0.631 and 1.277 cm root mean square error on simulated and human speech data, respectively. Empirical results show that the effectiveness of the proposed method is based on emphasizing higher formant frequencies, which seem less affected by speech articulation. Theoretical predictions of formant sensitivity reinforce this empirical finding. Moreover, theoretical insights are explained regarding the reason for differences in formant sensitivity. PMID:26177102

  5. On Short-Time Estimation of Vocal Tract Length from Formant Frequencies.

    PubMed

    Lammert, Adam C; Narayanan, Shrikanth S

    2015-01-01

    Vocal tract length is highly variable across speakers and determines many aspects of the acoustic speech signal, making it an essential parameter to consider for explaining behavioral variability. A method for accurate estimation of vocal tract length from formant frequencies would afford normalization of interspeaker variability and facilitate acoustic comparisons across speakers. A framework for considering estimation methods is developed from the basic principles of vocal tract acoustics, and an estimation method is proposed that follows naturally from this framework. The proposed method is evaluated using acoustic characteristics of simulated vocal tracts ranging from 14 to 19 cm in length, as well as real-time magnetic resonance imaging data with synchronous audio from five speakers whose vocal tracts range from 14.5 to 18.0 cm in length. Evaluations show improvements in accuracy over previously proposed methods, with 0.631 and 1.277 cm root mean square error on simulated and human speech data, respectively. Empirical results show that the effectiveness of the proposed method is based on emphasizing higher formant frequencies, which seem less affected by speech articulation. Theoretical predictions of formant sensitivity reinforce this empirical finding. Moreover, theoretical insights are explained regarding the reason for differences in formant sensitivity. PMID:26177102

  6. FY05 LDRD Final ReportTime-Resolved Dynamic Studies using Short Pulse X-Ray Radiation

    SciTech Connect

    Nelson, A; Dunn, J; van Buuren, T; Budil, K; Sadigh, B; Gilmer, G; Falcone, R; Lee, R; Ng, A

    2006-02-10

    Established techniques must be extended down to the ps and sub-ps time domain to directly probe product states of materials under extreme conditions. We used short pulse ({le} 1 ps) x-ray radiation to track changes in the physical properties in tandem with measurements of the atomic and electronic structure of materials undergoing fast laser excitation and shock-related phenomena. The sources included those already available at LLNL, including the picosecond X-ray laser as well as the ALS Femtosecond Phenomena beamline and the SSRL based sub-picosecond photon source (SPPS). These allow the temporal resolution to be improved by 2 orders of magnitude over the current state-of-the-art, which is {approx} 100 ps. Thus, we observed the manifestations of dynamical processes with unprecedented time resolution. Time-resolved x-ray photoemission spectroscopy and x-ray scattering were used to study phase changes in materials with sub-picosecond time resolution. These experiments coupled to multiscale modeling allow us to explore the physics of materials in high laser fields and extreme non-equilibrium states of matter. The ability to characterize the physical and electronic structure of materials under extreme conditions together with state-of-the-art models and computational facilities will catapult LLNL's core competencies into the scientific world arena as well as support its missions of national security and stockpile stewardship.

  7. Extracting Short Rise-Time Velocity Profiles with Digital Down-Shift Analysis of Optically Up-Converted PDV Data

    SciTech Connect

    Abel Diaz, Nathan Riley, Cenobio Gallegos, Matthew Teel, Michael Berninger, Thomas W. Tunnell

    2010-09-08

    This work describes the digital down-shift (DDS) technique, a new method of extracting short rise-time velocity profiles in the analysis of optically up-converted PDV data. The DDS technique manipulates the PDV data by subtracting a constant velocity (i.e., the DDS velocity ?DDS) from the velocity profile. DDS exploits the simple fact that the optically up-converted data ride on top of a base velocity (?0, the apparent velocity at no motion) with a rapid rise to a high velocity (?f) of a few km/s or more. Consequently, the frequency content of the signal must describe a velocity profile that increases from ?0 to ?0 + ?f. The DDS technique produces velocity reversals in the processed data before shock breakout when ?0 < ?DDS < ?0 + ?f. The DDS analysis process strategically selects specific DDS velocities (velocity at which the user down shifts the data) that produce anomalous reversals (maxima and/or minima), which are predictable and easy to identify in the mid-range of the data. Additional analysis determines when these maxima and minima occur. By successive application of the DDS technique and iterative analysis, velocity profiles are extracted as time as a function of velocity rather than as a function of time as it would be in a conventional velocity profile. Presented results include a description of DDS, velocity profiles extracted from laser-driven shock data with rise times of 200 ps or less, and a comparison with other techniques.

  8. Time-series of tritium, stable isotopes and chloride reveal short-term variations in groundwater contribution to a stream

    NASA Astrophysics Data System (ADS)

    Duvert, C.; Stewart, M. K.; Cendón, D. I.; Raiber, M.

    2015-08-01

    A major limitation to the accurate assessment of streamwater transit time (TT) stems from the use of stable isotopes or chloride as hydrological tracers, because these tracers are blind to older contributions. Also, while catchment processes are highly non-stationary, the importance of temporal dynamics in older water TT has often been overlooked. In this study we used lumped convolution models to examine time-series of tritium, stable isotopes and chloride in rainfall, streamwater and groundwater of a catchment located in subtropical Australia. Our objectives were to assess the different contributions to streamflow and their variations over time, and to understand the relationships between streamwater TT and groundwater residence time. Stable isotopes and chloride provided consistent estimates of TT in the upstream part of the catchment. A young component to streamflow was identified that was partitioned into quickflow (mean TT ? 2 weeks) and discharge from the fractured igneous rocks forming the headwaters (mean TT ? 0.3 years). The use of tritium was beneficial for determining an older contribution to streamflow in the downstream area. The best fits were obtained for a mean TT of 16-25 years for this older groundwater component. This was significantly lower than the residence time calculated for the alluvial aquifer feeding the stream downstream (? 76-102 years), outlining the fact that water exiting the catchment and water stored in it had distinctive age distributions. When simulations were run separately on each tritium streamwater sample, the TT of old water fraction varied substantially over time, with values averaging 17 ± 6 years at low flow and 38 ± 15 years after major recharge events. This was interpreted as the flushing out of deeper, older waters shortly after recharge by the resulting pressure wave propagation. Overall, this study shows the usefulness of collecting tritium data in streamwater to document short-term variations in the older component of the TT distribution. Our results also shed light on the complex relationships between stored water and water in transit, which are highly nonlinear and remain poorly understood.

  9. Operating envelope of a short contact time fuel reformer for propane catalytic partial oxidation

    NASA Astrophysics Data System (ADS)

    Waller, Michael G.; Walluk, Mark R.; Trabold, Thomas A.

    2015-01-01

    Fuel cell technology has yet to realize widespread deployment, in part because of the hydrogen fuel infrastructure required for proton exchange membrane systems. One option to overcome this barrier is to produce hydrogen by reforming propane, which has existing widespread infrastructure, is widely used by the general public, easily transported, and has a high energy density. The present work combines thermodynamic modeling of propane catalytic partial oxidation (cPOx) and experimental performance of a Precision Combustion Inc. (PCI) Microlith® reactor with real-time soot measurement. Much of the reforming research using Microlith-based reactors has focused on fuels such as natural gas, JP-8, diesel, and gasoline, but little research on propane reforming with Microlith-based catalysts can be found in literature. The aim of this study was to determine the optimal operating parameters for the reformer that maximizes efficiency and minimizes solid carbon formation. The primary parameters evaluated were reformate composition, carbon concentration in the effluent, and reforming efficiency as a function of catalyst temperature and O2/C ratio. Including the lower heating values for product hydrogen and carbon monoxide, efficiency of 84% was achieved at an O2/C ratio of 0.53 and a catalyst temperature of 940 °C, resulting in near equilibrium performance. Significant solid carbon formation was observed at much lower catalyst temperatures, and carbon concentration in the effluent was determined to have a negative linear relationship at T < 750 °C. The Microlith reactor displayed good stability during more than 80 experiments with temperature cycling from 360 to 1050 °C.

  10. A Distributed Web-based Solution for Ionospheric Model Real-time Management, Monitoring, and Short-term Prediction

    NASA Astrophysics Data System (ADS)

    Kulchitsky, A.; Maurits, S.; Watkins, B.

    2006-12-01

    With the widespread availability of the Internet today, many people can monitor various scientific research activities. It is important to accommodate this interest providing on-line access to dynamic and illustrative Web-resources, which could demonstrate different aspects of ongoing research. It is especially important to explain and these research activities for high school and undergraduate students, thereby providing more information for making decisions concerning their future studies. Such Web resources are also important to clarify scientific research for the general public, in order to achieve better awareness of research progress in various fields. Particularly rewarding is dissemination of information about ongoing projects within Universities and research centers to their local communities. The benefits of this type of scientific outreach are mutual, since development of Web-based automatic systems is prerequisite for many research projects targeting real-time monitoring and/or modeling of natural conditions. Continuous operation of such systems provide ongoing research opportunities for the statistically massive validation of the models, as well. We have developed a Web-based system to run the University of Alaska Fairbanks Polar Ionospheric Model in real-time. This model makes use of networking and computational resources at the Arctic Region Supercomputing Center. This system was designed to be portable among various operating systems and computational resources. Its components can be installed across different computers, separating Web servers and computational engines. The core of the system is a Real-Time Management module (RMM) written Python, which facilitates interactions of remote input data transfers, the ionospheric model runs, MySQL database filling, and PHP scripts for the Web-page preparations. The RMM downloads current geophysical inputs as soon as they become available at different on-line depositories. This information is processed to provide inputs for the next ionospheic model time step and then stored in a MySQL database as the first part of the time-specific record. The RMM then performs synchronization of the input times with the current model time, prepares a decision on initialization for the next model time step, and monitors its execution. Then, as soon as the model completes computations for the next time step, RMM visualizes the current model output into various short-term (about 1-2 hours) forecasting products and compares prior results with available ionospheric measurements. The RMM places prepared images into the MySQL database, which can be located on a different computer node, and then proceeds to the next time interval continuing the time-loop. The upper-level interface of this real-time system is the a PHP-based Web site (http://www.arsc.edu/SpaceWeather/new). This site provides general information about the Earth polar and adjacent mid-latitude ionosphere, allows for monitoring of the current developments and short-term forecasts, and facilitates access to the comparisons archive stored in the database.

  11. Alteration in scaling behavior of short-term heartbeat time series for professional shooting athletes from rest to exercise

    NASA Astrophysics Data System (ADS)

    Zhuang, Jian Jun; Ning, Xin Bao; He, Ai Jun; Zou, Ming; Sun, Biao; Wu, Xu Hui

    2008-11-01

    Scaling analysis of heartbeat time series has emerged as a useful tool for assessing the autonomic cardiac control under various physiologic and pathologic conditions. We study the heartbeat activity and scaling behavior of heartbeat fluctuations regulated by autonomic nervous system for professional shooting athletes under two states: rest and exercise, by applying the detrended fluctuation analysis method. We focus on alteration in correlation properties of heartbeat intervals for the shooters from rest to exercise, which may have a potential value in monitoring the quality of training and evaluating the sports capacity of the athletes. The result shows that scaling exponents of short-term heart rate variability signals from the shooters get significantly larger during exercise compared with those obtained at rest. It demonstrates that during exercise stronger correlations appear in the heartbeat series of shooting athletes in order to satisfy the specific requirements for high concentration and better control on their heart beats.

  12. Short-Time Procedure for the Determination of Woehler and Fatigue Life Curves Using Mechanical, Thermal and Electrical Data

    NASA Astrophysics Data System (ADS)

    Walther, Frank; Eifler, Dietmar

    Mechanical stress-strain hysteresis, temperature and electrical resistance measurements were performed to characterize the fatigue behavior and to calculate the lifetime of metals under constant amplitude loading and random loading. Constant amplitude sequences were periodically inserted in random load tests to measure the plastic strain amplitude as well as the deformation-induced changes in specimen temperature and electrical resistance. These data are plotted versus the number of cycles for the fatigue assessment under random loading, similar as commonly practiced under constant amplitude loading. On the basis of Morrow and Basquin equations in generalized formulations, to be applicable for mechanical, thermal and electrical measurement techniques, a physically based fatigue life calculation method “PHYBAL” was developed. This new short-time procedure requires data of only three fatigue tests for a rapid and nevertheless precise determination of Woehler curves for constant amplitude loading or fatigue life curves for random loading.

  13. Short-Term Chromospheric Variability in alpha Tauri (K5 III): Results from IUE Time Series Observations

    NASA Technical Reports Server (NTRS)

    Cuntz, Manfred; Deeney, Bryan D.; Brown, Alexander; Stencel, Robert E.

    1996-01-01

    We evaluate time series observations of chromospheric lines (Mg II, Mg I, and C II) for the K giant alpha Tau obtained using the IUE LWP camera at high dispersion. These observations cover a time span of about 2 weeks in 1994 February-March and were designed to resolve variations occurring within hours, days, and weeks. We consider the observational results in relation to theoretical acoustic heating models, motivated by the fact that alpha Tau may exhibit a basal (i.e., minimum) level of chromospheric activity. The data reveal flux variations between the extremes of 8% in Mg II h+k and 15% in each emission component. These variations occur on timescales as short as 8 hr but not on timescales longer than approx.3 days. For the h and k components, flux variations occurring on a timescale as short as 1.5 hr are also found. These changes are often not correlated (and are sometimes even anticorrelated), leading to remarkable differences in the h/k ratios. We argue that these results are consistent with the presence of strong acoustic shocks, which can lead to variable Mg II line emission when only a small number of strong shocks are propagating through the atmosphere. We deduce the electron density in the C II lambda 2325 line formation region to be log(base e) of N. approx. equals 9.0, in agreement with previous studies. Our data provide evidence that the Mg II basal flux limit for K giants might be a factor of 4 higher than suggested by Rutten et al.

  14. Seasonal comparisons of meteorological and agricultural drought indices in Morocco using open short time-series data

    NASA Astrophysics Data System (ADS)

    Ezzine, Hicham; Bouziane, Ahmed; Ouazar, Driss

    2014-02-01

    Although the preliminary investigations of NDWI demonstrated its sensitivity to vegetation water content, drought indices based on NDWI short time-series are still understudied compared to those derived from NDVI and LST, such as VCI, SVI and TCI. On the basis of the open data, this paper introduces a new index derived from NDWI short time-series, and explores its performance for drought monitoring in Mediterranean semi-arid area. The new index, Standardized Water Index (SWI), was calculated and spatiotemporally compared to both meteorological drought index (TRMM-based SPI) and to agricultural drought index (NDVI-based SVI) for the hydrological years and autumn, winter and spring seasons during a period of 15 years (1998-2012). Furthermore, the response and spatial agreement of the meteorological and agricultural drought indices (SWI, SVI and SPI) were compared over two land use classes, rainfed agriculture and vegetation cover, for the studied years and seasons. The validation of SWI was based on in situ SPI and cereal productions. The analysis of the 336 cross-tables, proportions of concordance and Cohen's kappa coefficients indicate that SWI and SVI are concordant comparing to other combinations for hydrological years and for the three seasons. The study points that the spatial agreements of drought indices over rainfed agriculture and over vegetation cover are different. It is relatively more important in the rainfed agriculture than in the vegetation cover areas. Our results show that the agreement between vegetation drought indices and meteorological drought indices is moderated to low and the SPI is slightly more concordant with SWI when it is compared to SVI in autumn and winter seasons. The validation approach indicates that drought affected area, according to SWI, is highly correlated with cereal production. Likewise, a satisfactory correlation was revealed between SWI and in situ SPI.

  15. Sodium magnetic resonance imaging using ultra-short echo time sequences with anisotropic resolution and uniform k-space sampling.

    PubMed

    Konstandin, Simon; Krämer, Philipp; Günther, Matthias; Schad, Lothar R

    2015-04-01

    A method for uniform k-space sampling of 3D ultra-short echo time (UTE) techniques with anisotropic resolution in one direction is introduced to increase signal-to-noise ratio (SNR). State-of-the-art acquisition schemes for sodium MRI with radial (projection reconstruction) and twisting (twisted projection imaging (TPI)) trajectories are investigated regarding SNR efficiency, blurring behavior under T2(?) decay, and measurement time in case of anisotropic field-of-view and resolution. 3D radial and twisting trajectories are redistributed in k-space for UTE sodium MRI with homogeneous noise distribution and optimal SNR efficiency, if T2(?) decay can be neglected. Simulations based on Voronoi tessellations and phantom simulations/measurements were performed to calculate SNR efficiency. Point-spread functions were simulated to demonstrate the influence of T2(?) decay on SNR and resolution. Phantom simulations/measurements and in vivo measurements confirm the SNR gain obtained by simulations based on Voronoi cells. An increase in SNR of up to 21% at an anisotropy factor of 10 could be theoretically achieved by TPI with projection adaption compared to the same sequence but without redistribution of projections in k-space. Sodium MRI with anisotropic resolution and uniform k-space sampling is demonstrated by in vivo measurements of human intervertebral disks and heart at 3 T. The SNR gain can be invested in a measurement time reduction of up to 32%, which is important especially for sodium MRI. PMID:25527394

  16. Thermal inactivation of Pediococcus sp. in simulated apple cider during high-temperature short-time pasteurization.

    PubMed

    Piyasena, P; McKellar, R C; Bartlett, F M

    2003-01-26

    Prompted by concerns regarding outbreaks of food-borne illness which have occurred due to the consumption of commercial, nonpasteurized fruit juices contaminated with Escherichia coli O157:H7, the US Food and Drug Administration and Canadian Food Inspection Agency are considering several new safety standards to apply to fresh juices, including mandatory pasteurization of all apple cider. In support of these initiatives, a study was conducted to evaluate the pasteurization of simulated cider using a heat-resistant nonpathogenic test bacterium, Pediococcus sp. NRRL B-2354. Thermal inactivation of the Pediococcus sp. was determined using a pilot scale high-temperature short-time (HTST) pasteurizer with a plate heat exchanger. The cumulative lethal effect, or pasteurization effect (PE), was obtained by converting times at different temperatures in the various sections of the pasteurizer to the equivalent time at the reference temperature (72 degrees C). PE was then related by a simple linear function to the log(10) of the percentage of viable counts with a power transformation of the PE values to improve linear fit. r(2) values for the four Pediococcus sp. trials varied from 0.921 to 0.981. Intertrial variation was incorporated into the model using @RISK simulation software. Output from simulations confirmed that treatment at 71 degrees C for 16 s can ensure a 5-log reduction of Pediococcus sp. PMID:12505457

  17. Interpreting short gamma-ray burst progenitor kicks and time delays using the host galaxy-dark matter halo connection

    SciTech Connect

    Behroozi, Peter S.; Ramirez-Ruiz, Enrico; Fryer, Christopher L.

    2014-09-10

    Nearly 20% of short gamma-ray bursts (sGRBs) have no observed host galaxies. Combining this finding with constraints on galaxies' dark matter halo potential wells gives strong limits on the natal kick velocity distribution for sGRB progenitors. For the best-fitting velocity distribution, one in five sGRB progenitors receives a natal kick above 150 km s{sup –1}, consistent with merging neutron star models but not with merging white dwarf binary models. This progenitor model constraint is robust to a wide variety of systematic uncertainties, including the sGRB progenitor time-delay model, the Swift redshift sensitivity, and the shape of the natal kick velocity distribution. We also use constraints on the galaxy-halo connection to determine the host halo and host galaxy demographics for sGRBs, which match extremely well with available data. Most sGRBs are expected to occur in halos near 10{sup 12} M {sub ?} and in galaxies near 5 × 10{sup 10} M {sub ?} (L {sub *}); unobserved faint and high-redshift host galaxies contribute a small minority of the observed hostless sGRB fraction. We find that sGRB redshift distributions and host galaxy stellar masses weakly constrain the progenitor time-delay model; the active versus passive fraction of sGRB host galaxies may offer a stronger constraint. Finally, we discuss how searches for gravitational wave optical counterparts in the local universe can reduce follow-up times using these findings.

  18. Classification mapping and species identification of salt marshes based on a short-time interval NDVI time-series from HJ-1 optical imagery

    NASA Astrophysics Data System (ADS)

    Sun, Chao; Liu, Yongxue; Zhao, Saishuai; Zhou, Minxi; Yang, Yuhao; Li, Feixue

    2016-03-01

    Salt marshes are seen as the most dynamic and valuable ecosystems in coastal zones, and in these areas, it is crucial to obtain accurate remote sensing information on the spatial distributions of species over time. However, discriminating various types of salt marsh is rather difficult because of their strong spectral similarities. Previous salt marsh mapping studies have focused mainly on high spatial and spectral (i.e., hyperspectral) resolution images combined with auxiliary information; however, the results are often limited to small regions. With a high temporal and moderate spatial resolution, the Chinese HuanJing-1 (HJ-1) satellite optical imagery can be used not only to monitor phenological changes of salt marsh vegetation over short-time intervals, but also to obtain coverage of large areas. Here, we apply HJ-1 satellite imagery to the middle coast of Jiangsu in east China to monitor changes in saltmarsh vegetation cover. First, we constructed a monthly NDVI time-series to classify various types of salt marsh and then we tested the possibility of using compressed time-series continuously, to broaden the applicability of this particular approach. Our principal findings are as follows: (1) the overall accuracy of salt marsh mapping based on the monthly NDVI time-series was 90.3%, which was ?16.0% higher than the single-phase classification strategy; (2) a compressed time-series, including NDVI from six key months (April, June-September, and November), demonstrated very little reduction (2.3%) in overall accuracy but led to obvious improvements in unstable regions; and (3) a simple rule for Spartina alterniflora identification was established using a scene solely from November, which may provide an effective way for regularly monitoring its distribution.

  19. Double peak-induced distance error in short-time-Fourier-transform-Brillouin optical time domain reflectometers event detection and the recovery method.

    PubMed

    Yu, Yifei; Luo, Linqing; Li, Bo; Guo, Linfeng; Yan, Jize; Soga, Kenichi

    2015-10-01

    The measured distance error caused by double peaks in the BOTDRs (Brillouin optical time domain reflectometers) system is a kind of Brillouin scattering spectrum (BSS) deformation, discussed and simulated for the first time in the paper, to the best of the authors' knowledge. Double peak, as a kind of Brillouin spectrum deformation, is important in the enhancement of spatial resolution, measurement accuracy, and crack detection. Due to the variances of the peak powers of the BSS along the fiber, the measured starting point of a step-shape frequency transition region is shifted and results in distance errors. Zero-padded short-time-Fourier-transform (STFT) can restore the transition-induced double peaks in the asymmetric and deformed BSS, thus offering more accurate and quicker measurements than the conventional Lorentz-fitting method. The recovering method based on the double-peak detection and corresponding BSS deformation can be applied to calculate the real starting point, which can improve the distance accuracy of the STFT-based BOTDR system. PMID:26479653

  20. Short residence times for alkaline Vesuvius magmas in a multi-depth supply system: Evidence from geochemical and textural studies

    NASA Astrophysics Data System (ADS)

    Pappalardo, Lucia; Mastrolorenzo, Giuseppe

    2010-07-01

    It is crucial to understand magma chamber chemico-physical conditions and residence times for high-risk volcanoes because these factors control the occurrence and size of future eruptions. In order to define magmatic pressure-temperature conditions and residence times at the Somma-Vesuvius volcano, we studied the geochemistry and texture of selected past eruptions that are representative of the entire volcanic history. Our petrological model indicates a multi-depth magma chamber composed of a deeper tephritic (350-400 Mpa) magma layer, which fed Strombolian and effusive eruptions during open-conduit activity, and an upper (200-250 Mpa) phonolitic level, which supplied the high explosive events that followed closed-conduit repose time. This upper reservoir matches the inferred transition between sedimentary sequences and metamorphic basement. At this level, the presence of a structural and lithological discontinuity favors magma storage during closed-conduit periods. The prevalent differentiation process was fractional crystallization during the magma cooling associated with upward migration of less dense, evolved liquids. Our results indicate that major steam exolution occurred during the late crystallization stage of phonolites, which accounts for the high Volcanic Explosivity Index (VEI) of eruptions supplied by these melts. Moreover, our phenocryst CSD data reveal the rapid crystallization and differentiation (decades to centuries) of alkaline Somma-Vesuvius magmas. This implies that the 400 km 2 partial melting zone detected by tomography studies at 8-10 km depth beneath Vesuvius should consist of differentiated magma that is already capable of generating a large-scale (plinian) explosive event if renewed activity develops out of the present closed-conduit state. Additionally, because our microlite CSD data indicate rapid magma migration from the chamber toward the surface, precursory activity could appear only short time before a major eruption.

  1. Bohr's atomic model revisited

    E-print Network

    Francisco Caruso; Vitor Oguri

    2008-06-03

    Bohr's atomic model, its relationship to the radiation spectrum of the hydrogen atom and the inherent hypotheses are revisited. It is argued that Bohr could have adopted a different approach, focusing his analyzes on the stationary orbit of the electron and its decomposition on two harmonic oscillators and then imposing, as actually he did, Planck's quantization for the oscillators' energies. Some consequences of this procedure are examined.

  2. Revisiting Dialogues and Monologues

    ERIC Educational Resources Information Center

    Kvernbekk, Tone

    2012-01-01

    In educational discourse dialogue tends to be viewed as being (morally) superior to monologue. When we look at them as basic forms of communication, we find that dialogue is a two-way, one-to-one form and monologue is a one-way, one-to-many form. In this paper I revisit the alleged (moral) superiority of dialogue. First, I problematize certain…

  3. Short Time Region Sparkover Characteristics of Compressed N2 and CO2 using Square Impulse and their Quantitative Estimation Method

    NASA Astrophysics Data System (ADS)

    Shinkai, Hiroyuki; Goshima, Hisashi; Yashima, Masafumi

    SF6 is used as a main insulation gas for gas-insulated switchgears (GIS), but it has recently become a gas to be restricted because of its greenhouse effect. Up to now, we have studied the insulation characteristics of compressed N2 and CO2 as a possible SF6-alternative gas. As GIS are subjected to very fast transient voltage due to incoming lightning surges or at disconnector switching operation, it is necessary to clarify the sparkover voltage-time (V-t) characteristics in the short time region. In this report, we describe the V-t curves ranging from 30ns to 10?s for high pressure (0.6 and 1.0MPa) N2 and CO2 obtained by applying square impulse voltage. We next studied the V-t curves for standard lightning and oscillating impulses for the same experimental conditions. Based on these results, we investigated the possibility of quantitatively estimating of the V-t curves for these waveforms by applying the “equal-area criterion”. The minimum sparkover voltage estimated by the criterion very well agreed with the measured characteristic in all conditions studied, and thus it has become clear that the quantitative estimation of the sparkover characteristics is possible for high pressure N2 and CO2.

  4. Long and short time variability of the global and the hemisphere temperature anomalies -Application of the Cochrane-Orcutt method

    NASA Astrophysics Data System (ADS)

    Werner, Rolf; Valev, Dimitare; Danov, Dimitar; Goranova, M.

    Climate change holds a key position in science and policy today. A central issue to discuss in the scientific publications is the question how much humans contribute to the climate warming. To get answers in the last decades a lot of efforts were made to model the processes determining the climate, to make forecasts under defined conditions for the development of the society (climate projections). Another scientific tendency to find a more probable right answer consists in the application and development of the statistics to study responses of different climate forcings. Here a classical statistical method -the linear regression -is applied to examine the parts of the global and hemisphere warming due to different radiation forcings, by the use of their long and short time variabilities. The residuals of the regressions are significantly auto-correlated. Therefore the Cochrane-Orcutt method is applied to test the statistical significances. By multiple regression it is found that the main part of the temperature variability is caused by CO2. The impact of the total solar irradiance during the examined time period of 1866 up to 2000 is at the critical level of significance.

  5. Time-dependent density functional theory of high-intensity short-pulse laser irradiation on insulators

    NASA Astrophysics Data System (ADS)

    Sato, S. A.; Yabana, K.; Shinohara, Y.; Otobe, T.; Lee, K.-M.; Bertsch, G. F.

    2015-11-01

    We calculate the energy deposition by very short laser pulses in SiO2 (? -quartz) with a view to establishing systematics for predicting damage and nanoparticle production. The theoretical framework is time-dependent density functional theory, implemented by the real-time method in a multiscale representation. For the most realistic simulations we employ a meta-GGA Kohn-Sham potential similar to that of Becke and Johnson. We find that the deposited energy in the medium can be accurately modeled as a function of the local electromagnetic pulse fluence. The energy-deposition function can in turn be quite well fitted to the strong-field Keldysh formula for a range of intensities from below the melting threshold to well beyond the ablation threshold. We find reasonable agreement between the damage threshold and the energy required to melt the substrate. Also, the depth of the ablated crater at higher energies is fairly well reproduced assuming that the material ablated with the energy exceeds that required to convert it to an atomic fluid. However, the calculated ablation threshold is higher than experiment, suggesting a nonthermal mechanism for the surface ablation.

  6. Nucleoside uptake in macrophages from various murine strains: a short-time and a two-step stimulation model

    SciTech Connect

    Busolo, F.; Conventi, L.; Grigolon, M.; Palu, G. )

    1991-06-28

    Kinetics of (3H)-uridine uptake by murine peritoneal macrophages (pM phi) is early altered after exposure to a variety of stimuli. Alterations caused by Candida albicans, lipopolysaccharide (LPS) and recombinant interferon-gamma (rIFN-gamma) were similar in SAVO, C57BL/6, C3H/HeN and C3H/HeJ mice, and were not correlated with an activation process as shown by the amount of tumor necrosis factor-alpha (TNF-alpha) being released. Short-time exposure to all stimuli resulted in an increased nucleoside uptake by SAVO pM phi, suggesting that the tumoricidal function of this cell either depends from the type of stimulus or the time when the specific interaction with the cell receptor is taking place. Experiments with priming and triggering signals confirmed the above findings, indicating that the increase or the decrease of nucleoside uptake into the cell depends essentially on the chemical nature of the priming stimulus. The triggering stimulus, on the other hand, is only able to amplify the primary response.

  7. Shorting time of magnetically insulated reflex-ion diodes from the neutral-atom charge-exchange mechanism

    SciTech Connect

    Strobel, G.

    1981-10-01

    In a magnetically insulated diode, collision-free electrons return to the cathode and no electron current is present at the anode. Electron transport to the anode is studied in this paper. Steady-state space-charge-limited flow is assumed initially. Breakdown of ion flow occurs when static neutral atoms at the anode undergo charge exchange, which results in neutral atoms drifting across the diode. These are subsequently ionized by reflexing ions producing electrons trapped in Larmor orbits throughout the diode. These electrons drift to the anode via ionization and inelastic collisions with other neutral atoms. Model calculations compare the effects of foil and mesh cathodes. Steady-state space-charge-limited ion current densities are calculated. The neutral atom density at the cathode is determined as a function of time. The shorting time of the diode is scaled versus the electrode separation d, the diode potential V/sub 0/, the magnetic field, and the initial concentration of static neutron atoms.

  8. Mi-1-Mediated Nematode Resistance in Tomatoes is Broken by Short-Term Heat Stress but Recovers Over Time

    PubMed Central

    Marques de Carvalho, Luciana; Benda, Nicole D.; Vaughan, Martha M.; Cabrera, Ana R.; Hung, Kaddie; Cox, Thomas; Abdo, Zaid; Allen, L. Hartwell; Teal, Peter E. A.

    2015-01-01

    Tomato (Solanum lycopersicum L.) is among the most valuable agricultural products, but Meloidogyne spp. (root-knot nematode) infestations result in serious crop losses. In tomato, resistance to root-knot nematodes is controlled by the gene Mi-1, but heat stress interferes with Mi-1-associated resistance. Inconsistent results in published field and greenhouse experiments led us to test the effect of short-term midday heat stress on tomato susceptibility to Meloidogyne incognita race 1. Under controlled day/night temperatures of 25°C/21°C, ‘Amelia’, which was verified as possessing the Mi-1 gene, was deemed resistant (4.1 ± 0.4 galls/plant) and Rutgers, which does not possess the Mi-1 gene, was susceptible (132 ± 9.9 galls/plant) to M. incognita infection. Exposure to a single 3 hr heat spike of 35°C was sufficient to increase the susceptibility of ‘Amelia’ but did not affect Rutgers. Despite this change in resistance, Mi-1 gene expression was not affected by heat treatment, or nematode infection. The heat-induced breakdown of Mi-1 resistance in ‘Amelia’ did recover with time regardless of additional heat exposures and M. incognita infection. These findings would aid in the development of management strategies to protect the tomato crop at times of heightened M. incognita susceptibility. PMID:26170475

  9. A Bayesian method for characterizing distributed micro-releases: II. inference under model uncertainty with short time-series data.

    SciTech Connect

    Marzouk, Youssef; Fast P. (Lawrence Livermore National Laboratory, Livermore, CA); Kraus, M.; Ray, J. P.

    2006-01-01

    Terrorist attacks using an aerosolized pathogen preparation have gained credibility as a national security concern after the anthrax attacks of 2001. The ability to characterize such attacks, i.e., to estimate the number of people infected, the time of infection, and the average dose received, is important when planning a medical response. We address this question of characterization by formulating a Bayesian inverse problem predicated on a short time-series of diagnosed patients exhibiting symptoms. To be of relevance to response planning, we limit ourselves to 3-5 days of data. In tests performed with anthrax as the pathogen, we find that these data are usually sufficient, especially if the model of the outbreak used in the inverse problem is an accurate one. In some cases the scarcity of data may initially support outbreak characterizations at odds with the true one, but with sufficient data the correct inferences are recovered; in other words, the inverse problem posed and its solution methodology are consistent. We also explore the effect of model error-situations for which the model used in the inverse problem is only a partially accurate representation of the outbreak; here, the model predictions and the observations differ by more than a random noise. We find that while there is a consistent discrepancy between the inferred and the true characterizations, they are also close enough to be of relevance when planning a response.

  10. Interactions of Grazing History, Cattle Removal and Time since Rain Drive Divergent Short-Term Responses by Desert Biota

    PubMed Central

    Frank, Anke S. K.; Dickman, Chris R.; Wardle, Glenda M.; Greenville, Aaron C.

    2013-01-01

    Arid grasslands are used worldwide for grazing by domestic livestock, generating debate about how this pastoral enterprise may influence native desert biota. One approach to resolving this question is to experimentally reduce livestock numbers and measure the effects. However, a key challenge in doing this is that historical grazing impacts are likely to be cumulative and may therefore confound comparisons of the short-term responses of desert biota to changes in stocking levels. Arid areas are also subject to infrequent flooding rainfalls that drive productivity and dramatically alter abundances of flora and fauna. We took advantage of an opportunity to study the recent effects of a property-scale cattle removal on two properties with similarly varied grazing histories in central Australia. Following the removal of cattle in 2006 and before and after a significant rainfall event at the beginning of 2007, we sampled vegetation and small vertebrates on eight occasions until October 2008. Our results revealed significant interactions of time of survey with both grazing history and grazing removal for vascular plants, small mammals and reptiles. The mammals exhibited a three-way interaction of time, grazing history and grazing removal, thus highlighting the importance of careful sampling designs and timing for future monitoring. The strongest response to the cessation of grazing after two years was depressed reproductive output of plants in areas where cattle continued to graze. Our results confirm that neither vegetation nor small vertebrates necessarily respond immediately to the removal of livestock, but that rainfall events and cumulative grazing history are key determinants of floral and faunal performance in grassland landscapes with low and variable rainfall. We suggest that improved assessments could be made of the health of arid grazing environments if long-term monitoring were implemented to track the complex interactions that influence how native biota respond to grazing. PMID:23874635

  11. Mission Design and Analysis for Suborbital Intercept and Fragmentation of an Asteroid with Very Short Warning Time

    NASA Technical Reports Server (NTRS)

    Hupp, Ryan; DeWald, Spencer; Wie, Bong; Barbee, Brent W.

    2014-01-01

    Small near-Earth objects (NEOs) approximately 50-150 m in size are far more numerous (hundreds of thousands to millions yet to be discovered) than larger NEOs. Small NEOs, which are mostly asteroids rather than comets, are very faint in the night sky due to their small sizes, and are, therefore, difficult to discover far in advance of Earth impact. Furthermore, even small NEOs are capable of creating explosions with energies on the order of tens or hundreds of megatons (Mt). We are, therefore, motivated to prepare to respond effectively to short warning time, small NEO impact scenarios. In this paper we explore the lower bound on actionable warning time by investigating the performance of notional upgraded Intercontinental Ballistic Missiles (ICBMs) to carry Nuclear Explosive Device (NED) payloads to intercept and disrupt a hypothetical incoming NEO at high altitudes (generally at least 2500 km above Earth). We conduct this investigation by developing optimal NEO intercept trajectories for a range of cases and comparing their performances. Our results show that suborbital NEO intercepts using Minuteman III or SM-3 IIA launch vehicles could achieve NEO intercept a few minutes prior to when the NEO would strike Earth. We also find that more powerful versions of the launch vehicles (e.g., total delta V of approximately 9.5-11 km/s) could intercept incoming NEOs several hours prior to when the NEO would strike Earth, if launched at least several days prior to the time of intercept. Finally, we discuss a number of limiting factors and practicalities that affect whether the notional systems we describe could become feasible.

  12. Electrocardiogram Signal and Linear Time-Frequency Transforms

    NASA Astrophysics Data System (ADS)

    Krishna, B. T.

    2014-12-01

    The diagnostic analysis of non-stationary multi component signals such as electrocardiogram (ECG) involves the use of time-frequency transforms. So, the application of time-frequency transforms to an ECG signal is an important problem of research. In this paper, initially, linear transforms like short time Fourier transform, continuous wavelet transforms, s-transform etc. are revisited. Then the application of these transforms to normal and abnormal ECG signals is illustrated. It has been observed that s-transform provides better time and frequency resolution compared to other linear transforms. The fractional Fourier transform provides rotation to the spectrogram representation.

  13. 26 CFR 1.6074-2 - Time for filing declarations by corporations in case of a short taxable year.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... of more than 9 months, where the requirements of section 6016(a) are first met after the last day of the 8th month, but before the 1st day of the last month of the short taxable year, the declaration shall be filed on or before the 15th day of the last month of such short year. See § 1.6016-4,...

  14. Short time-scale analysis of the NW Mediterranean ecosystem during summer-autumn transition: A 1D modelling approach

    NASA Astrophysics Data System (ADS)

    Raybaud, V.; Nival, P.; Prieur, L.

    2011-01-01

    Modelling was used as a tool to better understand the physical and biological processes observed during the multidisciplinary cruise DYNAPROC 2 (DYNAmic of rapid PROCesses in the water column), which took place in the Ligurian Sea in September-October 2004. The aim of the cruise was to study the short time-scale physical and biological processes that occur when the ecosystem switches from summer oligotrophy to autumnal mesotrophy. In this study, we have tested two 1D physical-biological coupled models. The first was a classical model in which surface layer dynamics were obtained using the turbulent kinetic energy model of Gaspar [Gaspar et al., 1990]. The simulated food-web took into account ten state variables: three nutrients, three classes of phytoplankton, two classes of zooplankton and two types of detritus. The second model (called IDA, Isopycnals Depth Adjustment) was based on the initial one but it took into account the measured variations of isopycnals depths. The results showed that the IDA model most efficiently reproduced the observed ecosystem dynamics. We have therefore used the IDA model to show that physical processes observed during the cruise had a major effect on biological compartment, mainly on nano- and picophytoplankton.

  15. Short time-scale AGN X-ray variability with EXOSAT: black hole mass and normalized variability amplitude

    NASA Astrophysics Data System (ADS)

    McHardy, I. M.

    2013-03-01

    The old EXOSAT medium energy measurements of high-frequency (HF) active galactic nuclei (AGN) power spectral normalization are re-examined in the light of accurate black hole mass determinations which were not available when these data were first published by Green et al. It is found that the normalized variability amplitude (NVA), measured directly from the power spectrum, is proportional to M?, where ? ˜ -0.54 ± 0.08. As NVA is the square root of the power, these observations show that the normalization of the HF power spectrum for this sample of AGN varies very close to inversely with black hole mass. Almost the same value of ? is obtained whether the quasar 3C 273 is included in the sample or not, suggesting that the same process that drives X-ray variability in Seyfert galaxies applies also to 3C 273. These observations support the work of Gierli?ski et al. who show that an almost exactly linear anticorrelation is required if the normalizations of the HF power spectra of AGN and X-ray binary systems are to scale similarly. These observations are also consistent with a number of studies showing that the short time-scale variance of AGN X-ray light curves varies approximately inversely with mass.

  16. Radiolytic Cryovolcanism Revisited

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.; Cooper, P. D.; Sittler, E. C.; Wesenberg, R. P.

    2013-12-01

    Active geysers of water vapor and ice grains from the south pole of Enceladus are not yet definitively explained in terms of energy sources and processes. Other instances of hot (Io) and cold (Mars, Triton) volcanism beyond Earth are known if not fully understood. We revisit, in comparison to other models, the 'Old Faithful' theory of radiolytic gas-driven cryovolcanism first proposed by Cooper et al. [Plan. Sp. Sci. 2009]. In the energetic electron irradiation environment of Enceladus within Saturn's magnetosphere, a 10-percent duty cycle could be maintained for current geyser activity driven by gases from oxidation of ammonia to N2 and methane to CO2 in the thermal margins of a south polar sea. Much shorter duty cycles down to 0.01 percent would be required to account for thermal power output up to 16 GW, Steady accumulation of oxidant energy over four billion years could have powered all Enceladus emissions over the past four hundred thousand to four hundred million years. There could be separate energy sources driving mass flow and thermal emission over vastly different time scales. Since episodic tidal dissipation on 10 Myr time scales at 0.1 - 1 Gyr intervals [O'Neill and Nimmo, Nature 2010], and thus duty cycles 1 - 10 percent, could heat the polar sea to the current level, the radiolytic energy source could easily power and modulate the geyser mass flow on million-year time scales. Maximum thermal emission temperature 223 K [Abramov and Spencer, Icarus 2009] hints at thermal buffering in the basal and vent wall layers by a 1:1 H2O:H2O2 radiolytic eutectic, assuming deep ice crust saturation with H2O2 from long cumulative surface irradiation and downward ice convection. Due to density stratification the peroxide eutectic and salt water layers could separate, so that the denser peroxide layer (1.2 g/cc) descends to the polar sea while the lighter salt water (1.05 g/cc) rises along separate channels. Methane reservoirs could be found dissolved into the polar sea, or else trapped in hydrates [Kieffer et al., Science 2006] along flow paths and at the walls of the polar sea at surface depths below 20 km [Fortes, Icarus 2007]. Driver gas production for cryovolcanism could occur wherever these two layers come into contact under requisite temperature and pressure conditions, e.g. from 220 K and 10 bar at the 10-km basal layer of the overlying ice crust to 647 K and 220 bars at the liquid water limit, above the core-mantle boundary at 460 bars [Fortes, Icarus 2007]. We expect H2O2 oxidation to ignite at high temperatures but metallic minerals could catalyze reactions at lower temperatures nearer the basal layer. Pressure effects on oxidation rates are uncertain. Definitive modeling of Enceladus cryovolcanism likely involves synthesis of key processes from multiple models: Cold Faithful [Porco et al., Science 2006], Frigid Faithful [Keiffer et al., Science 2006], Frothy Faithful [Fortes, Icarus 2007], Old Faithful, and 'Perrier Ocean' recirculation [Matson et al., Icarus 2012].

  17. Short contact time direct coal liquefaction using a novel batch reactor. Quarterly technical progress report, September 15, 1995--January 15, 1996

    SciTech Connect

    Klein, M.T.; Calkins, W.H.; Huang, He

    1996-01-26

    The objective of this research is to optimize the design and operation of the bench scale batch reactor (SCTBR) f or coal liquefaction at short contact times (0.01 to 10 minutes or longer). Additional objectives are to study the kinetics of direct coal liquefaction particularly at short reaction times, and to investigate the role of the organic oxygen components of coal and their reaction pathways during liquefaction. Many of those objectives have already been achieved and others are still in progress. This quarterly report covers further progress toward those objectives.

  18. Preparatory Body State before Reacting to an Opponent: Short-Term Joint Torque Fluctuation in Real-Time Competitive Sports

    PubMed Central

    Fujii, Keisuke; Yamashita, Daichi; Kimura, Tetsuya; Isaka, Tadao; Kouzaki, Motoki

    2015-01-01

    In a competitive sport, the outcome of a game is determined by an athlete’s relationship with an unpredictable and uncontrolled opponent. We have previously analyzed the preparatory state of ground reaction forces (GRFs) dividing non-weighted and weighted states (i.e., vertical GRFs below and above 120% of body weight, respectively) in a competitive ballgame task and demonstrated that the non-weighted state prevented delay of the defensive step and promoted successful guarding. However, the associated kinetics of lower extremity joints during a competitive sports task remains unknown. The present study aims to investigate the kinetic characteristics of a real-time competitive sport before movement initiation. As a first kinetic study on a competitive sport, we initially compared the successful defensive kinetics with a relatively stable preparatory state and the choice-reaction sidestep as a control movement. Then, we investigated the kinetic cause of the outcome in a 1-on-1 dribble in terms of the preparatory states according to our previous study. The results demonstrated that in successful defensive motions in the non-weighted state guarding trial, the times required for the generation of hip abduction and three extension torques for the hip, knee, and ankle joints were significantly shortened compared with the choice-reaction sidestep, and hip abduction and hip extension torques were produced almost simultaneously. The sport-specific movement kinetics emerges only in a more-realistic interactive experimental setting. A comparison of the outcomes in the 1-on-1 dribble and preparatory GRF states showed that, in the non-weighted state, the defenders guarded successfully in 68.0% of the trials, and the defender’s initiation time was earlier than that in the weighted state (39.1%). In terms of kinetics, the root mean squares of the derivative of hip abduction and three extension torques in the non-weighted state were smaller than those in the weighted state, irrespective of the outcome. These results indicate that the preparatory body state as explained by short-term joint torque fluctuations before the defensive step would help explain the performance in competitive sports, and will give insights into understanding human adaptive behavior in unpredicted and uncontrolled environments. PMID:26024485

  19. "Parallel" transport - revisited

    E-print Network

    Stasheff, Jim

    2011-01-01

    Parallel transport in a fibre bundle with respect to smooth paths in the base space B have recently been extended to representations of the smooth singular simplicial set Sing_{smooth}(B). Inspired by these extensions,I revisit the development of a notion of `parallel' transport in the topological setting of fibrations with the homotopy lifting property and then extend it to representations of Sing(B) on such fibrations. Closely related is the notion of (strong or `infty') homotopy action, which has variants under a variety of names.

  20. Short-time windowed covariance: A metric for identifying non-stationary, event-related covariant cortical sites

    PubMed Central

    Blakely, Timothy; Ojemann, Jeffrey G.; Rao, Rajesh P.N.

    2014-01-01

    Background Electrocorticography (ECoG) signals can provide high spatio-temporal resolution and high signal to noise ratio recordings of local neural activity from the surface of the brain. Previous studies have shown that broad-band, spatially focal, high-frequency increases in ECoG signals are highly correlated with movement and other cognitive tasks and can be volitionally modulated. However, significant additional information may be present in inter-electrode interactions, but adding additional higher order inter-electrode interactions can be impractical from a computational aspect, if not impossible. New method In this paper we present a new method of calculating high frequency interactions between electrodes called Short-Time Windowed Covariance (STWC) that builds on mathematical techniques currently used in neural signal analysis, along with an implementation that accelerates the algorithm by orders of magnitude by leveraging commodity, off-the-shelf graphics processing unit (GPU) hardware. Results Using the hardware-accelerated implementation of STWC, we identify many types of event-related inter-electrode interactions from human ECoG recordings on global and local scales that have not been identified by previous methods. Unique temporal patterns are observed for digit flexion in both low- (10 mm spacing) and high-resolution (3 mm spacing) electrode arrays. Comparison with existing methods Covariance is a commonly used metric for identifying correlated signals, but the standard covariance calculations do not allow for temporally varying covariance. In contrast STWC allows and identifies event-driven changes in covariance without identifying spurious noise correlations. Conclusions: STWC can be used to identify event-related neural interactions whose high computational load is well suited to GPU capabilities. PMID:24211499

  1. Inflammatory and metabolic markers and short-time outcome in patients with acute ischemic stroke in relation to TOAST subtypes.

    PubMed

    Lehmann, Marcio Francisco; Kallaur, Ana Paula; Oliveira, Sayonara Rangel; Alfieri, Daniela Frizon; Delongui, Franciele; de Sousa Parreira, Johnathan; de Araújo, Maria Caroline Martins; Rossato, Carolina; de Almeida, Jéssica Tavares; Pelegrino, Larissa Moliterno; Bragato, Erick Frank; Lehmann, Ana Lucia Cruz Fürstenberger; Morimoto, Helena Kaminami; Lozovoy, Marcell Alysson Batisti; Simão, Andrea Name Colado; Kaimen-Maciel, Damácio Ramon; Reiche, Edna Maria Vissoci

    2015-12-01

    The aim of this study was to evaluate the association between inflammatory and metabolic markers and short-time outcome with acute ischemic stroke subtypes. A total of 121 patients was classified according to TOAST criteria, such as large artery atherosclerosis (LAAS), lacunar infarct (LAC), cardioembolic infarct (CEI), other determined etiology (ODE), and undetermined etiology (UDE). The functional impairment was evaluated within the first eight hours of stroke and the outcome after three-month follow-up using the modified Rankin Scale. Blood samples were obtained up to 24 h of stroke. Compared with 96 controls, patients with LAAS, CEI, and LAC subtypes showed higher levels of white blood cells, high-sensitivity C-reactive protein (hsCRP), interleukin 6 (IL-6), metalloproteinase 9 (MMP-9), glucose, and iron (p?

  2. A Wearable Technology Revisited for Cardio-Respiratory Functional Exploration

    E-print Network

    Fontecave-Jallon, Julie

    A Wearable Technology Revisited for Cardio-Respiratory Functional Exploration: Stroke Volume-respiratory (CR) measure is a well-known wearable solution. We applied time-scale analysis to estimate cardiac of vital and behavioral signs is an emerging concept of healthcare. Although wearable technology is more

  3. Revisiting Constructivist Teaching Methods in Ontario Colleges Preparing for Accreditation

    ERIC Educational Resources Information Center

    Schultz, Rachel A.

    2015-01-01

    At the time of writing, the first community colleges in Ontario were preparing for transition to an accreditation model from an audit system. This paper revisits constructivist literature, arguing that a more pragmatic definition of constructivism effectively blends positivist and interactionist philosophies to achieve both student centred…

  4. The sun compass revisited

    PubMed Central

    Guilford, Tim; Taylor, Graham K.

    2014-01-01

    Many animals, and birds in particular, are thought to use directional information from the sun in the form of a time-compensated sun compass, with predictably deviated orientation under clock shift being regarded as the litmus test of this. We suggest that this paradigm obscures a number of other ways in which solar-derived information could be important in animal orientation. We distinguish between the known use of the sun's azimuth to provide absolute geographical direction (compass mechanism) and its possible use to detect changes in heading (heading indicator mechanism). Just as in an aircraft, these two kinds of information may be provided by separate mechanisms and used for different functions, for example for navigation versus steering. We also argue that although a solar compass must be time-referenced to account for the sun's apparent diurnal movement, this need not entail full time compensation. This is because animals might also use time-dependent solar information in an associatively acquired, and hence time-limited, way. Furthermore, we show that a solar heading indicator, when used on a sufficiently short timescale, need not require time compensation at all. Finally, we suggest that solar-derived cues, such as shadows, could also be involved in navigation in ways that depend explicitly upon position, and are therefore not strictly compass-related. This could include giving directionality to landmarks, or acting as time-dependent landmarks involved in place recognition. We conclude that clock shift experiments alone are neither necessary nor sufficient to identify the occurrence of all conceivable uses of solar information in animal orientation, so that a predictable response to clock shift should not be regarded as an acid test of the use of solar information in navigation. PMID:25389374

  5. Changes in Children's Perception-Action Tuning over Short Time Scales: Bicycling across Traffic-Filled Intersections in a Virtual Environment

    ERIC Educational Resources Information Center

    Plumert, Jodie M.; Kearney, Joseph K.; Cremer, James F.; Recker, Kara M.; Strutt, Jonathan

    2011-01-01

    This investigation examined short-term changes in child and adult cyclists' gap decisions and movement timing in response to general and specific road-crossing experiences. Children (10- and 12-year-olds) and adults rode a bicycle through a virtual environment with 12 intersections. Participants faced continuous cross traffic and waited for gaps…

  6. Phase transitions and critical phenomena in the two-dimensional Ising model with dipole interactions: A short-time dynamics study

    NASA Astrophysics Data System (ADS)

    Horowitz, C. M.; Bab, M. A.; Mazzini, M.; Puzzo, M. L. Rubio; Saracco, G. P.

    2015-10-01

    The ferromagnetic Ising model with antiferromagnetic dipole interactions is investigated by means of Monte Carlo simulations, focusing on the characterization of the phase transitions between the tetragonal liquid and stripe of width h phases. The dynamic evolution of the physical observables is analyzed within the short-time regime for 0.5 ?? ?1.3 , where ? is the ratio between the short-range exchange and the long-range dipole interaction constants. The obtained results for the interval 0.5 ?? ?1.2 indicate that the phase transition line between the h =1 stripe and tetragonal liquid phases is continuous. This finding contributes to clarifying the controversy about the order of this transition. This controversy arises from the difficulties introduced in the simulations due to the presence of long-range dipole interactions, such as an important increase in the simulation times that limits the system size used, strong finite size effects, as well as to the existence of multiple metastable states at low temperatures. The study of the short-time dynamics of the model allows us to avoid these hindrances. Moreover, due to the fact that the finite-size effects do not significantly affect the power-law behavior exhibited in the observables within the short-time regime, the results could be attributed to those corresponding to the thermodynamic limit. As a consequence of this, a careful characterization of the critical behavior for the whole transition line is performed by giving the complete set of critical exponents.

  7. Using the Advanced Progressive Matrices (Set I) to Assess Fluid Ability in a Short Time Frame: An Item Response Theory-Based Analysis

    ERIC Educational Resources Information Center

    Chiesi, Francesca; Ciancaleoni, Matteo; Galli, Silvia; Primi, Caterina

    2012-01-01

    This article is aimed at evaluating the possibility that Set I of the Advanced Progressive Matrices (APM-Set I) can be employed to assess fluid ability in a short time frame. The APM-Set I was administered to a sample of 1,389 primary and secondary school students. Confirmatory factor analysis attested to the unidimensionality of the scale. Item…

  8. A voxel-based investigation for MRI-only radiotherapy of the brain using ultra short echo times.

    PubMed

    Edmund, Jens M; Kjer, Hans M; Van Leemput, Koen; Hansen, Rasmus H; Andersen, Jon A L; Andreasen, Daniel

    2014-12-01

    Radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, so-called MRI-only RT, would remove the systematic registration error between MR and computed tomography (CT), and provide co-registered MRI for assessment of treatment response and adaptive RT. Electron densities, however, need to be assigned to the MRI images for dose calculation and patient setup based on digitally reconstructed radiographs (DRRs). Here, we investigate the geometric and dosimetric performance for a number of popular voxel-based methods to generate a so-called pseudo CT (pCT). Five patients receiving cranial irradiation, each containing a co-registered MRI and CT scan, were included. An ultra short echo time MRI sequence for bone visualization was used. Six methods were investigated for three popular types of voxel-based approaches; (1) threshold-based segmentation, (2) Bayesian segmentation and (3) statistical regression. Each approach contained two methods. Approach 1 used bulk density assignment of MRI voxels into air, soft tissue and bone based on logical masks and the transverse relaxation time T2 of the bone. Approach 2 used similar bulk density assignments with Bayesian statistics including or excluding additional spatial information. Approach 3 used a statistical regression correlating MRI voxels with their corresponding CT voxels. A similar photon and proton treatment plan was generated for a target positioned between the nasal cavity and the brainstem for all patients. The CT agreement with the pCT of each method was quantified and compared with the other methods geometrically and dosimetrically using both a number of reported metrics and introducing some novel metrics. The best geometrical agreement with CT was obtained with the statistical regression methods which performed significantly better than the threshold and Bayesian segmentation methods (excluding spatial information). All methods agreed significantly better with CT than a reference water MRI comparison. The mean dosimetric deviation for photons and protons compared to the CT was about 2% and highest in the gradient dose region of the brainstem. Both the threshold based method and the statistical regression methods showed the highest dosimetrical agreement.Generation of pCTs using statistical regression seems to be the most promising candidate for MRI-only RT of the brain. Further, the total amount of different tissues needs to be taken into account for dosimetric considerations regardless of their correct geometrical position. PMID:25393873

  9. A voxel-based investigation for MRI-only radiotherapy of the brain using ultra short echo times

    NASA Astrophysics Data System (ADS)

    Edmund, Jens M.; Kjer, Hans M.; Van Leemput, Koen; Hansen, Rasmus H.; Andersen, Jon AL; Andreasen, Daniel

    2014-12-01

    Radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, so-called MRI-only RT, would remove the systematic registration error between MR and computed tomography (CT), and provide co-registered MRI for assessment of treatment response and adaptive RT. Electron densities, however, need to be assigned to the MRI images for dose calculation and patient setup based on digitally reconstructed radiographs (DRRs). Here, we investigate the geometric and dosimetric performance for a number of popular voxel-based methods to generate a so-called pseudo CT (pCT). Five patients receiving cranial irradiation, each containing a co-registered MRI and CT scan, were included. An ultra short echo time MRI sequence for bone visualization was used. Six methods were investigated for three popular types of voxel-based approaches; (1) threshold-based segmentation, (2) Bayesian segmentation and (3) statistical regression. Each approach contained two methods. Approach 1 used bulk density assignment of MRI voxels into air, soft tissue and bone based on logical masks and the transverse relaxation time T2 of the bone. Approach 2 used similar bulk density assignments with Bayesian statistics including or excluding additional spatial information. Approach 3 used a statistical regression correlating MRI voxels with their corresponding CT voxels. A similar photon and proton treatment plan was generated for a target positioned between the nasal cavity and the brainstem for all patients. The CT agreement with the pCT of each method was quantified and compared with the other methods geometrically and dosimetrically using both a number of reported metrics and introducing some novel metrics. The best geometrical agreement with CT was obtained with the statistical regression methods which performed significantly better than the threshold and Bayesian segmentation methods (excluding spatial information). All methods agreed significantly better with CT than a reference water MRI comparison. The mean dosimetric deviation for photons and protons compared to the CT was about 2% and highest in the gradient dose region of the brainstem. Both the threshold based method and the statistical regression methods showed the highest dosimetrical agreement. Generation of pCTs using statistical regression seems to be the most promising candidate for MRI-only RT of the brain. Further, the total amount of different tissues needs to be taken into account for dosimetric considerations regardless of their correct geometrical position.

  10. Three-dimensional accurate detection of lung emphysema in rats using ultra-short and zero echo time MRI.

    PubMed

    Bianchi, Andrea; Tibiletti, Marta; Kjørstad, Åsmund; Birk, Gerald; Schad, Lothar R; Stierstorfer, Birgit; Rasche, Volker; Stiller, Detlef

    2015-11-01

    Emphysema is a life-threatening pathology that causes irreversible destruction of alveolar walls. In vivo imaging techniques play a fundamental role in the early non-invasive pre-clinical and clinical detection and longitudinal follow-up of this pathology. In the present study, we aimed to evaluate the feasibility of using high resolution radial three-dimensional (3D) zero echo time (ZTE) and 3D ultra-short echo time (UTE) MRI to accurately detect lung pathomorphological changes in a rodent model of emphysema.Porcine pancreas elastase (PPE) was intratracheally administered to the rats to produce the emphysematous changes. 3D ZTE MRI, low and high definition 3D UTE MRI and micro-computed tomography images were acquired 4 weeks after the PPE challenge. Signal-to-noise ratios (SNRs) were measured in PPE-treated and control rats. T2 * values were computed from low definition 3D UTE MRI. Histomorphometric measurements were made after euthanizing the animals. Both ZTE and UTE MR images showed a significant decrease in the SNR measured in PPE-treated lungs compared with controls, due to the pathomorphological changes taking place in the challenged lungs. A significant decrease in T2 * values in PPE-challenged animals compared with controls was measured using UTE MRI. Histomorphometric measurements showed a significant increase in the mean linear intercept in PPE-treated lungs. UTE yielded significantly higher SNR compared with ZTE (14% and 30% higher in PPE-treated and non-PPE-treated lungs, respectively).This study showed that optimized 3D radial UTE and ZTE MRI can provide lung images of excellent quality, with high isotropic spatial resolution (400 µm) and SNR in parenchymal tissue (>25) and negligible motion artifacts in freely breathing animals. These techniques were shown to be useful non-invasive instruments to accurately and reliably detect the pathomorphological alterations taking place in emphysematous lungs, without incurring the risks of cumulative radiation exposure typical of micro-computed tomography. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26403226

  11. Consistency of the triplet seesaw model revisited

    NASA Astrophysics Data System (ADS)

    Bonilla, Cesar; Fonseca, Renato M.; Valle, J. W. F.

    2015-10-01

    Adding a scalar triplet to the Standard Model is one of the simplest ways of giving mass to neutrinos, providing at the same time a mechanism to stabilize the theory's vacuum. In this paper, we revisit these aspects of the type-II seesaw model pointing out that the bounded-from-below conditions for the scalar potential in use in the literature are not correct. We discuss some scenarios where the correction can be significant and sketch the typical scalar boson profile expected by consistency.

  12. L'enfant et les sortilèges revisited.

    PubMed

    Hindle, D

    2000-12-01

    The author discusses 'L'Enfant et les sortilèges', an opera by Ravel based on a short story by Colette, which traces the trials and tribulations of a young boy whose bad behaviour leads to his being sent to his room, left alone and given only tea and bread until dinner. His progression from anger to persecution and fear, the various defences he employs to protect himself from feeling overwhelmed and his despair are graphically illustrated through words and music. The author considers the opera in relation to Klein's theory of the paranoidschizoid position and the struggle involved in maintaining contact with good objects, externally and internally. Revisiting the opera in light of Meltzer's contribution to psychoanalytic thinking provides a wider perspective in which to explore what he has termed the aesthetic conflict and its place in relation to the depressive position and developmental processes. PMID:11144856

  13. Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

    DOEpatents

    Veligdan, James T. (Manorville, NY)

    1994-01-01

    An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90.degree. angle of incidence.

  14. Spatial resolution in depth for time-resolved diffuse optical tomography using short source-detector separations

    PubMed Central

    Puszka, Agathe; Di Sieno, Laura; Mora, Alberto Dalla; Pifferi, Antonio; Contini, Davide; Planat-Chrétien, Anne; Koenig, Anne; Boso, Gianluca; Tosi, Alberto; Hervé, Lionel; Dinten, Jean-Marc

    2014-01-01

    Diffuse optical tomography for medical applications can require probes with small dimensions involving short source-detector separations. Even though this configuration is seen at first as a constraint due to the challenge of depth sensitivity, we show here that it can potentially be an asset for spatial resolution in depth. By comparing two fiber optic probes on a test object, we first show with simulations that short source-detector separations improve the spatial resolution down to a limit depth. We then confirm these results in an experimental study with a state-of-the-art setup involving a fast-gated single-photon avalanche diode allowing maximum depth sensitivity. We conclude that short source-detector separations are an option to consider for the design of probes so as to improve image quality for diffuse optical tomography in reflectance. PMID:25657869

  15. Spatial resolution in depth for time-resolved diffuse optical tomography using short source-detector separations.

    PubMed

    Puszka, Agathe; Di Sieno, Laura; Mora, Alberto Dalla; Pifferi, Antonio; Contini, Davide; Planat-Chrétien, Anne; Koenig, Anne; Boso, Gianluca; Tosi, Alberto; Hervé, Lionel; Dinten, Jean-Marc

    2015-01-01

    Diffuse optical tomography for medical applications can require probes with small dimensions involving short source-detector separations. Even though this configuration is seen at first as a constraint due to the challenge of depth sensitivity, we show here that it can potentially be an asset for spatial resolution in depth. By comparing two fiber optic probes on a test object, we first show with simulations that short source-detector separations improve the spatial resolution down to a limit depth. We then confirm these results in an experimental study with a state-of-the-art setup involving a fast-gated single-photon avalanche diode allowing maximum depth sensitivity. We conclude that short source-detector separations are an option to consider for the design of probes so as to improve image quality for diffuse optical tomography in reflectance. PMID:25657869

  16. Revisiting Interpretation of Canonical Correlation Analysis: A Tutorial and Demonstration of Canonical Commonality Analysis

    ERIC Educational Resources Information Center

    Nimon, Kim; Henson, Robin K.; Gates, Michael S.

    2010-01-01

    In the face of multicollinearity, researchers face challenges interpreting canonical correlation analysis (CCA) results. Although standardized function and structure coefficients provide insight into the canonical variates produced, they fall short when researchers want to fully report canonical effects. This article revisits the interpretation of…

  17. Revisiting Levy flight search patterns of wandering albatrosses, bumblebees and deer

    E-print Network

    Buldyrev, Sergey

    LETTERS Revisiting Le´vy flight search patterns of wandering albatrosses, bumblebees and deer importance1 , and exemplifies the wider scientific problem of optimizing search strategies2 . Le´vy flights,4 , such that clusters of short steps are con- nected by rare long steps. Le´vy flights display fractal properties, have

  18. Automatized near-real-time short-term Probabilistic Volcanic Hazard Assessment of tephra dispersion before eruptions: BET_VHst for Vesuvius and Campi Flegrei during recent exercises

    NASA Astrophysics Data System (ADS)

    Selva, Jacopo; Costa, Antonio; Sandri, Laura; Rouwet, Dmtri; Tonini, Roberto; Macedonio, Giovanni; Marzocchi, Warner

    2015-04-01

    Probabilistic Volcanic Hazard Assessment (PVHA) represents the most complete scientific contribution for planning rational strategies aimed at mitigating the risk posed by volcanic activity at different time scales. The definition of the space-time window for PVHA is related to the kind of risk mitigation actions that are under consideration. Short temporal intervals (days to weeks) are important for short-term risk mitigation actions like the evacuation of a volcanic area. During volcanic unrest episodes or eruptions, it is of primary importance to produce short-term tephra fallout forecast, and frequently update it to account for the rapidly evolving situation. This information is obviously crucial for crisis management, since tephra may heavily affect building stability, public health, transportations and evacuation routes (airports, trains, road traffic) and lifelines (electric power supply). In this study, we propose a methodology named BET_VHst (Selva et al. 2014) for short-term PVHA of volcanic tephra dispersal based on automatic interpretation of measures from the monitoring system and physical models of tephra dispersal from all possible vent positions and eruptive sizes based on frequently updated meteorological forecasts. The large uncertainty at all the steps required for the analysis, both aleatory and epistemic, is treated by means of Bayesian inference and statistical mixing of long- and short-term analyses. The BET_VHst model is here presented through its implementation during two exercises organized for volcanoes in the Neapolitan area: MESIMEX for Mt. Vesuvius, and VUELCO for Campi Flegrei. References Selva J., Costa A., Sandri L., Macedonio G., Marzocchi W. (2014) Probabilistic short-term volcanic hazard in phases of unrest: a case study for tephra fallout, J. Geophys. Res., 119, doi: 10.1002/2014JB011252

  19. Balancing the Need for Reliability and Time Efficiency: Short Forms of the Wechsler Adult Intelligence Scale-III

    ERIC Educational Resources Information Center

    Jeyakumar, Sharon L. E.; Warriner, Erin M.; Raval, Vaishali V.; Ahmad, Saadia A.

    2004-01-01

    Tables permitting the conversion of short-form composite scores to full-scale IQ estimates have been published for previous editions of the Wechsler Adult Intelligence Scale (WAIS). Equivalent tables are now needed for selected subtests of the WAIS-III. This article used Tellegen and Briggs's formulae to convert the sum of scaled scores for four…

  20. 26 CFR 1.6074-2 - Time for filing declarations by corporations in case of a short taxable year.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Time for filing declarations by corporations...CONTINUED) INCOME TAXES (CONTINUED) Time for Filing Returns and Other Documents § 1.6074-2 Time for filing declarations by...

  1. 26 CFR 1.6074-2 - Time for filing declarations by corporations in case of a short taxable year.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Time for filing declarations by corporations...INCOME TAX (CONTINUED) INCOME TAXES Time for Filing Returns and Other Documents § 1.6074-2 Time for filing declarations by...

  2. 26 CFR 1.6074-2 - Time for filing declarations by corporations in case of a short taxable year.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Time for filing declarations by corporations...CONTINUED) INCOME TAXES (CONTINUED) Time for Filing Returns and Other Documents § 1.6074-2 Time for filing declarations by...

  3. 26 CFR 1.6074-2 - Time for filing declarations by corporations in case of a short taxable year.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Time for filing declarations by corporations...CONTINUED) INCOME TAXES (CONTINUED) Time for Filing Returns and Other Documents § 1.6074-2 Time for filing declarations by...

  4. 26 CFR 1.6074-2 - Time for filing declarations by corporations in case of a short taxable year.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Time for filing declarations by corporations...CONTINUED) INCOME TAXES (CONTINUED) Time for Filing Returns and Other Documents § 1.6074-2 Time for filing declarations by...

  5. Highly controlled synthesis of nanometric gold particles by citrate reduction using the short mixing, heating and quenching times achievable in a microfluidic device

    NASA Astrophysics Data System (ADS)

    Ftouni, Jamal; Penhoat, Maël; Addad, Ahmed; Payen, Edmond; Rolando, Christian; Girardon, Jean-Sébastien

    2012-07-01

    Homodispersed 1.8 nm gold nanoparticles were obtained reproducibly in high yields using the classical Turkevich protocol at a high concentration in a continuous flow capillary reactor. The microfluidic reactor made from commercially available items permitted short mixing, heating and quenching times which are the key parameters of this synthesis.Homodispersed 1.8 nm gold nanoparticles were obtained reproducibly in high yields using the classical Turkevich protocol at a high concentration in a continuous flow capillary reactor. The microfluidic reactor made from commercially available items permitted short mixing, heating and quenching times which are the key parameters of this synthesis. Electronic supplementary information (ESI) available: Description of the microfluidic device, protocol for gold nanoparticle synthesis in batch and in the microsystem, and gold nanoparticle size distribution raw data. See DOI: 10.1039/c2nr11666a

  6. Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

    DOEpatents

    Veligdan, J.T.

    1994-03-08

    An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90[degree] angle of incidence. 8 figures.

  7. Short stature

    MedlinePLUS

    Idiopathic short stature; Non-growth hormone deficient short stature ... Turner syndrome Williams syndrome Other reasons include: Growth hormone deficiency Infections of the developing baby before birth ...

  8. Re-visiting the nature and relationships between neurological signs and neurocognitive functions in first-episode schizophrenia: An invariance model across time

    PubMed Central

    Chan, Raymond C. K.; Dai, Shan; Lui, Simon S. Y.; Ho, Karen K. Y.; Hung, Karen S. Y.; Wang, Ya; Geng, Fu-lei; Li, Zhi; Cheung, Eric F. C.

    2015-01-01

    The present study examined different types of neurological signs in patients with first-episode schizophrenia and their relationships with neurocognitive functions. Both cross-sectional and longitudinal designs were adopted with the use of the abridged Cambridge Neurological Inventory which comprises items capturing motor coordination, sensory integration and disinhibition. A total of 157 patients with first-episode schizophrenia were assessed at baseline and 101 of them were re-assessed at six-month interval. A structural equation model (SEM) with invariance model across time was used for data analysis. The model fitted well with the data at baseline assessment, X^2(21)?=?21.78, p?=?0.413, NFI?=?0.95, NNFI?=?1.00, CFI?=?1.00, IFI?=?1.00, RMSEA?=?0.015. Subsequent SEM analysis with invariance model at six-month interval also demonstrated the same stable pattern across time and showed strong measurement invariance and structure invariance across time. Our findings suggest that neurological signs capture more or less the same construct captured by conventional neurocognitive tests in patients with schizophrenia. The measurement and structure of these relationships appear to be stable over time. PMID:26136150

  9. The bacterial nucleoid revisited.

    PubMed Central

    Robinow, C; Kellenberger, E

    1994-01-01

    This review compares the results of different methods of investigating the morphology of nucleoids of bacteria grown under conditions favoring short generation times. We consider the evidence from fixed and stained specimens, from phase-contrast and fluorescence microscopy of growing bacteria, and from electron microscopy of whole as well as thinly sectioned ones. It is concluded that the nucleoid of growing cells is in a dynamic state: part of the chromatin is "pulled out" of the bulk of the nucleoid in order to be transcribed. This activity is performed by excrescences which extend far into the cytoplasm so as to reach the maximum of available ribosomes. Different means of fixation provide markedly different views of the texture of the DNA-containing plasm of the bulk of the nucleoid. Conventional chemical fixatives stabilize the cytoplasm of bacteria but not their protein-low chromatin. Uranyl acetate does cross-link the latter well but only if the cytoplasm has first been fixed conventionally. In the interval between the two fixations, the DNA arranges itself in liquid-crystalline form, supposedly because of loss of supercoiling. In stark contrast, cryofixation preserves bacterial chromatin in a finely granular form, believed to reflect its native strongly negatively supercoiled state. In dinoflagellates the DNA of their permanently visible chromosomes (also low in histone-like protein) is natively present as a liquid crystal. The arrangement of chromatin in Epulocystis fishelsoni, one of the largest known prokaryotes, is briefly described. Images PMID:7521510

  10. The Revolving Door Phenomenon Revisited: Time to Readmission in 17’415 Patients with 37’697 Hospitalisations at a German Psychiatric Hospital

    PubMed Central

    Frick, Ulrich; Frick, Hannah; Langguth, Berthold; Landgrebe, Michael; Hübner-Liebermann, Bettina; Hajak, Göran

    2013-01-01

    Objective Despite the recurring nature of the disease process in many psychiatric patients, individual careers and time to readmission rarely have been analysed by statistical models that incorporate sequence and velocity of recurrent hospitalisations. This study aims at comparing four statistical models specifically designed for recurrent event history analysis and evaluating the potential impact of predictor variables from different sources (patient, treatment process, social environment). Method The so called Andersen-Gil counting process model, two variants of the conditional models of Prentice, Williams, and Peterson (gap time model, conditional probability model), and the so called frailty model were applied to a dataset of 17’415 patients observed during a 12 years period starting from 1996 and leading to 37’697 psychiatric hospitalisations. Potential prognostic factors stem from a standardized patient documentation form. Results Estimated regression coefficients over different models were highly similar, but the frailty model best represented the sequentiality of individual treatment careers and differing velocities of disease progression. It also avoided otherwise likely misinterpretations of the impact of gender, partnership, historical time and length of stay. A widespread notion of psychiatric diseases as inevitably chronic and worsening could be rejected. Time in community was found to increase over historical time for all patients. Most important protective factors beyond diagnosis were employment, partnership, and sheltered living situation. Risky conditions were urban living and a concurrent substance use disorder. Conclusion Prognostic factors for course of diseases should be determined only by statistical models capable of adequately incorporating the recurrent nature of psychiatric illnesses. PMID:24116059

  11. Cretaceous eustasy revisited

    NASA Astrophysics Data System (ADS)

    Haq, Bilal U.

    2014-02-01

    Eustatic sea-level changes of the Cretaceous are reevaluated based on a synthesis of global stratigraphic data. A new terminology for local/regional or relative sea-level changes (eurybatic shifts) is proposed to distinguish them from global (eustatic) sea-level changes, with the observation that all measures of sea-level change in any given location are eurybatic, even when they include a strong global signal. Solid-earth factors that influence inherited regional topography and thus modify physical measures of amplitude of the sea-level rises and falls locally are reviewed. One of these factors, dynamic topography (surface expression of mass flow in the upper mantle on land- and seascapes), is considered most pertinent in altering local measures of amplitude of sea-level events on third-order time scales (0.5-3.0 Myr). Insights gained from these models have led to the reconciliation of variance between amplitude estimates of eurybatic shifts in any given region and global measures of eustatic changes. Global estimates of third-order events can only be guesstimated at best by averaging the eurybatic data from widely distributed time-synchronous events. Revised curves for both long-term and short-term sea-level variations are presented for the Cretaceous Period. The curve representing the long-term envelope shows that average sea levels throughout the Cretaceous remained higher than the present day mean sea level (75-250 m above PDMSL). Sea level reached a trough in mid Valanginian (~ 75 m above PDMSL), followed by two high points, the first in early Barremian (~ 160-170 m above PDMSL) and the second, the highest peak of the Cretaceous, in earliest Turonian (~ 240-250 m above PDMSL). The curve also displays two ~ 20 Myr-long periods of relatively high and stable sea levels (Aptian through early Albian and Coniacian through Campanian). The short-term curve identifies 58 third-order eustatic events in the Cretaceous, most have been documented in several basins, while a smaller number are included provisionally as eustatic, awaiting confirmation. The amplitude of sea-level falls varies from a minimum of ~ 20 m to a maximum of just over 100 m and the duration varies between 0.5 and 3 Myr. The causes for these relatively rapid, and at times large amplitude, sea-level falls in the Cretaceous remain unresolved, although based mainly on oxygen-isotopic data, the presence of transient ice cover on Antarctica as the driver remains in vogue as an explanation. This idea has, however, suffered a recent setback following the discovery of pristine foraminiferal tests in the Turonian of Tanzania whose oxygen-isotopic values show little variation, implying absence of glacioeustasy at least in the Turonian. The prevalence of 4th-order (~ 400 Kyr) cyclicity through most of the Cretaceous (and elsewhere in the Paleozoic, Jurassic and Cenozoic) implies that the periodicity on this time scale, presumably driven by long-term orbital eccentricity, may be a fundamental feature of depositional sequences throughout the Phanerozoic.

  12. Automatized near-real-time short-term Probabilistic Volcanic Hazard Assessment of tephra dispersion before and during eruptions: BET_VHst for Mt. Etna

    NASA Astrophysics Data System (ADS)

    Selva, Jacopo; Scollo, Simona; Costa, Antonio; Brancato, Alfonso; Prestifilippo, Michele

    2015-04-01

    Tephra dispersal, even in small amounts, may heavily affect public health and critical infrastructures, such as airports, train and road networks, and electric power supply systems. Probabilistic Volcanic Hazard Assessment (PVHA) represents the most complete scientific contribution for planning rational strategies aimed at managing and mitigating the risk posed by activity during volcanic crises and during eruptions. Short-term PVHA (over time intervals in the order of hours to few days) must account for rapidly changing information coming from the monitoring system, as well as, updated wind forecast, and they must be accomplished in near-real-time. In addition, while during unrest the primary goal is to forecast potential eruptions, during eruptions it is also fundamental to correctly account for the real-time status of the eruption and of tephra dispersal, as well as its potential evolution in the short-term. Here, we present a preliminary application of BET_VHst model (Selva et al. 2014) for Mt. Etna. The model has its roots into present state deterministic procedure, and it deals with the large uncertainty that such procedures typically ignore, like uncertainty on the potential position of the vent and eruptive size, on the possible evolution of volcanological input during ongoing eruptions, as well as, on wind field. Uncertainty is treated by making use of Bayesian inference, alternative modeling procedures for tephra dispersal, and statistical mixing of long- and short-term analyses. References Selva J., Costa A., Sandri L., Macedonio G., Marzocchi W. (2014) Probabilistic short-term volcanic hazard in phases of unrest: a case study for tephra fallout, J. Geophys. Res., 119, doi: 10.1002/2014JB011252

  13. The linkages among hillslope-vegetation changes, elevation, and the timing of late-Quaternary fluvial-system aggradation in the Mojave Desert revisited

    NASA Astrophysics Data System (ADS)

    Pelletier, J. D.

    2014-08-01

    Valley-floor-channel and alluvial-fan deposits and terraces in the southwestern US record multiple episodes of late-Quaternary fluvial-system aggradation and incision. Perhaps the most well-constrained of these episodes took place from the latest Pleistocene to the present in the Mojave Desert. One hypothesis for this episode - i.e., the paleovegetation-change hypothesis (PVCH) - posits that a reduction in hillslope vegetation cover associated with the transition from Pleistocene woodlands to Holocene desert scrub generated a pulse of sediment that triggered a primary phase of aggradation downstream, followed by channel incision, terrace abandonment, and initiation of a secondary phase of aggradation further downstream. A second hypothesis - i.e., the extreme-storm hypothesis - attributes episodes of aggradation and incision to changes in the frequency and/or intensity of extreme storms. In the past decade a growing number of studies has advocated the extreme-storm hypothesis and challenged the PVCH on the basis of inconsistencies in both timing and process. Here I show that in eight out of nine sites where the timing of fluvial-system aggradation in the Mojave Desert is reasonably well constrained, measured ages of primary aggradation are consistent with the predictions of the PVCH if the time-transgressive nature of paleovegetation changes with elevation is fully taken into account. I also present an alternative process model for PVCH that is more consistent with available data and produces sediment pulses primarily via an increase in drainage density (i.e., a transformation of hillslopes into low-order channels) rather than solely via an increase in sediment yield from hillslopes. This paper further documents the likely important role of changes in upland vegetation cover and drainage density in driving fluvial-system response during semiarid-to-arid climatic changes.

  14. Revisiting caspases in sepsis

    PubMed Central

    Aziz, M; Jacob, A; Wang, P

    2014-01-01

    Sepsis is a life-threatening illness that occurs due to an abnormal host immune network which extends through the initial widespread and overwhelming inflammation, and culminates at the late stage of immunosupression. Recently, interest has been shifted toward therapies aimed at reversing the accompanying periods of immune suppression. Studies in experimental animals and critically ill patients have demonstrated that increased apoptosis of lymphoid organs and some parenchymal tissues contributes to this immune suppression, anergy and organ dysfunction. Immediate to the discoveries of the intracellular proteases, caspases for the induction of apoptosis and inflammation, and their striking roles in sepsis have been focused elaborately in a number of original and review articles. Here we revisited the different aspects of caspases in terms of apoptosis, pyroptosis, necroptosis and inflammation and focused their links in sepsis by reviewing several recent findings. In addition, we have documented striking perspectives which not only rewrite the pathophysiology, but also modernize our understanding for developing novel therapeutics against sepsis. PMID:25412304

  15. Searle's"Dualism Revisited"

    SciTech Connect

    P., Henry

    2008-11-20

    A recent article in which John Searle claims to refute dualism is examined from a scientific perspective. John Searle begins his recent article 'Dualism Revisited' by stating his belief that the philosophical problem of consciousness has a scientific solution. He then claims to refute dualism. It is therefore appropriate to examine his arguments against dualism from a scientific perspective. Scientific physical theories contain two kinds of descriptions: (1) Descriptions of our empirical findings, expressed in an every-day language that allows us communicate to each other our sensory experiences pertaining to what we have done and what we have learned; and (2) Descriptions of a theoretical model, expressed in a mathematical language that allows us to communicate to each other certain ideas that exist in our mathematical imaginations, and that are believed to represent, within our streams of consciousness, certain aspects of reality that we deem to exist independently of their being perceived by any human observer. These two parts of our scientific description correspond to the two aspects of our general contemporary dualistic understanding of the total reality in which we are imbedded, namely the empirical-mental aspect and the theoretical-physical aspect. The duality question is whether this general dualistic understanding of ourselves should be regarded as false in some important philosophical or scientific sense.

  16. Comment on "Late-time tails of a self-gravitating massless scalar field revisited" by Bizon et al: The leading order asymptotics

    E-print Network

    Nikodem Szpak

    2009-08-12

    In Class. Quantum Grav. 26 (2009) 175006 (arXiv:0812.4333v3) Bizon et al discuss the power-law tail in the long-time evolution of a spherically symmetric self-gravitating massless scalar field in odd spatial dimensions. They derive explicit expressions for the leading order asymptotics for solutions with small initial data by using formal series expansions. Unfortunately, this approach misses an interesting observation that the actual decay rate is a product of asymptotic cancellations occurring due to a special structure of the nonlinear terms. Here, we show that one can calculate the leading asymptotics more directly by recognizing the special structure and cancellations already on the level of the wave equation.

  17. V405 ANDROMEDA REVISITED

    SciTech Connect

    Ribeiro, T.; Kafka, S.

    2011-10-15

    We present a multi-epoch time-resolved high-resolution optical spectroscopy study of the short-period (P{sub orb} = 11.2 hr) eclipsing M0V+M5V RS CVn binary V405 Andromeda. By means of indirect imaging techniques, namely Doppler imaging, we study the surface activity features of the M0V component of the system. A modified version of a Doppler imaging code, which takes into account the tidal distortion of the surface of the star, is applied to the multi-epoch data set in order to provide indirect images of the stellar surface. The multi-epoch surface brightness distributions show a low intensity 'belt' of spots at latitudes {+-}40{sup 0} and a noticeable absence of high latitude features or polar spots on the primary star of V405 Andromeda. They also reveal slow evolution of the spot distribution over {approx}4 yr. An entropy landscape procedure is used in order to find the set of binary parameters that lead to the smoothest surface brightness distributions. As a result, we find M{sub 1} = 0.51 {+-} 0.03 M{sub sun}, M{sub 2} = 0.21 {+-} 0.01 M{sub sun}, R{sub 1} = 0.71 {+-} 0.01 R{sub sun}, and an inclination i = 65{sup 0} {+-} 1{sup 0}. The resulting systemic velocity is distinct for different epochs, raising the possibility of the existence of a third body in the system.

  18. 25 CFR 26.30 - Does the Job Training Program provide part-time training or short-term training?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Does the Job Training Program provide part-time training...DEPARTMENT OF THE INTERIOR HUMAN SERVICES JOB PLACEMENT AND TRAINING PROGRAM Training Services § 26.30 Does the Job Training Program provide part-time...

  19. 25 CFR 26.30 - Does the Job Training Program provide part-time training or short-term training?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Does the Job Training Program provide part-time training...DEPARTMENT OF THE INTERIOR HUMAN SERVICES JOB PLACEMENT AND TRAINING PROGRAM Training Services § 26.30 Does the Job Training Program provide part-time...

  20. 25 CFR 26.30 - Does the Job Training Program provide part-time training or short-term training?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Does the Job Training Program provide part-time training...DEPARTMENT OF THE INTERIOR HUMAN SERVICES JOB PLACEMENT AND TRAINING PROGRAM Training Services § 26.30 Does the Job Training Program provide part-time...

  1. 25 CFR 26.30 - Does the Job Training Program provide part-time training or short-term training?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2011-04-01 true Does the Job Training Program provide part-time training...DEPARTMENT OF THE INTERIOR HUMAN SERVICES JOB PLACEMENT AND TRAINING PROGRAM Training Services § 26.30 Does the Job Training Program provide part-time...

  2. 25 CFR 26.30 - Does the Job Training Program provide part-time training or short-term training?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Does the Job Training Program provide part-time training...DEPARTMENT OF THE INTERIOR HUMAN SERVICES JOB PLACEMENT AND TRAINING PROGRAM Training Services § 26.30 Does the Job Training Program provide part-time...

  3. Expression of Flowering-Time Genes in Soybean E1 Near-isogenic Lines Under Short and Long Day Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of soybean flowering time is important for geographic adaptation, and maximizing yield. Plant breeders have identified a series of genes (E genes) that condition time to flowering, however, the molecular basis in the control of flowering by these E genes, in conjunction with canonical flowe...

  4. Heliocentric Distance of Coronal Mass Ejections at the Time of Energetic Particle Release: Revisiting the Ground Level Enhancement Events of Solar Cycle 23

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Natchimuthuk

    2011-01-01

    Using the kinematics of coronal mass ejections (CMEs), onset time of soft X-ray flares, and the finite size of the pre-eruption CME structure, we derive the heliocentric distane at which the energetic particles during the ground level enhancement (GLE) events of Solar Cycle 23. We find that the GLE particles are released when the CMEs reach an average heliocentric distance of approx.3.25 solar radii (Rs). From this we infer that the shocks accelerating the particles are located at similar heights. Type II radio burst observations indicate that the CMEs are at much lower distances (average approx.1.4 Rs) when the CME-driven shock first forms. The shock seems to travel approx.1.8 Rs over a period of approox.30 min on the average before releasing the GLE particles. In deriving these results, we made three assumptions that have observational support: (i) the CME lift off occurs from an initial distance of about 1.25 Rs; (ii) the flare onset and CME onset are one and the same because these are two different manifestations of the same eruption; and (iii) the CME has positive acceleration from the onset to the first appearance in the coronagraphic field of view (2.5 to 6 Rs). Observations of coronal cavities in eclipse pictures and in coronagraphic images justify the assumption (i). The close relationship between the flare reconnection magnetic flux and the azimuthal flux of interplanetary magnetic clouds justify assumption (ii) consistent with the standard model (CSHKP) of solar eruption. Coronagraphic observations made close to the solar surface indicate a large positive acceleration of CMEs to a heliocentric distance of approx.3 Rs before they start slowing down due to the drag force. The inferred acceleration (approx.1.5 km/s/s) is consistent with reported values in the literature.

  5. The "Mushroom Cloud" Demonstration Revisited

    ERIC Educational Resources Information Center

    Panzarasa, Guido; Sparnacci, Katia

    2013-01-01

    A revisitation of the classical "mushroom cloud" demonstration is described. Instead of aniline and benzoyl peroxide, the proposed reaction involves household chemicals such as alpha-pinene (turpentine oil) and trichloroisocyanuric acid ("Trichlor") giving an impressive demonstration of oxidation and combustion reactions that…

  6. Human short-term exposure to electromagnetic fields emitted by mobile phones decreases computer-assisted visual reaction time.

    PubMed

    Mortazavi, S M J; Rouintan, M S; Taeb, S; Dehghan, N; Ghaffarpanah, A A; Sadeghi, Z; Ghafouri, F

    2012-06-01

    The worldwide dramatic increase in mobile phone use has generated great concerns about the detrimental effects of microwave radiations emitted by these communication devices. Reaction time plays a critical role in performing tasks necessary to avoid hazards. As far as we know, this study is the first survey that reports decreased reaction time after exposure to electromagnetic fields generated by a high specific absorption rate mobile phone. It is also the first study in which previous history of mobile phone use is taken into account. The aim of this study was to assess both the acute and chronic effects of electromagnetic fields emitted by mobile phones on reaction time in university students. Visual reaction time (VRT) of young university students was recorded with a simple blind computer-assisted-VRT test, before and after a 10 min real/sham exposure to electromagnetic fields of mobile phones. Participants were 160 right-handed university students aged 18-31. To assess the effect of chronic exposures, the reaction time in sham-exposed phases were compared among low level, moderate and frequent users of mobile phones. The mean ± SD reaction time after real exposure and sham exposure were 286.78 ± 31.35 ms and 295.86 ± 32.17 ms (P < 0.001), respectively. The age of students did not significantly alter the reaction time either in talk or in standby mode. The reaction time either in talk or in standby mode was shorter in male students. The students' VRT was significantly affected by exposure to electromagnetic fields emitted by a mobile phone. It can be concluded that these exposures cause decreased reaction time, which may lead to a better response to different hazards. In this light, this phenomenon might decrease the chances of human errors and fatal accidents. PMID:22426673

  7. Short-Term Memory for Space and Time Flexibly Recruit Complementary Sensory-Biased Frontal Lobe Attention Networks.

    PubMed

    Michalka, Samantha W; Kong, Lingqiang; Rosen, Maya L; Shinn-Cunningham, Barbara G; Somers, David C

    2015-08-19

    The frontal lobes control wide-ranging cognitive functions; however, functional subdivisions of human frontal cortex are only coarsely mapped. Here, functional magnetic resonance imaging reveals two distinct visual-biased attention regions in lateral frontal cortex, superior precentral sulcus (sPCS) and inferior precentral sulcus (iPCS), anatomically interdigitated with two auditory-biased attention regions, transverse gyrus intersecting precentral sulcus (tgPCS) and caudal inferior frontal sulcus (cIFS). Intrinsic functional connectivity analysis demonstrates that sPCS and iPCS fall within a broad visual-attention network, while tgPCS and cIFS fall within a broad auditory-attention network. Interestingly, we observe that spatial and temporal short-term memory (STM), respectively, recruit visual and auditory attention networks in the frontal lobe, independent of sensory modality. These findings not only demonstrate that both sensory modality and information domain influence frontal lobe functional organization, they also demonstrate that spatial processing co-localizes with visual processing and that temporal processing co-localizes with auditory processing in lateral frontal cortex. PMID:26291168

  8. Time-resolved imaging with OKE-based time-gate: enhancement in spatial resolution using low-coherence ultra-short illumination

    E-print Network

    Purwar, Harsh; Rozé, Claude; Blaisot, Jean-Bernard

    2015-01-01

    We propose a collinear optical Kerr effect (OKE) based time-gate configuration with low coherence illumination source, derived from the supercontinuum (SC) generated by focusing the femtosecond laser pulses inside water. At first the spectral broadening in SC generation and corresponding changes in its coherence properties are studied and then a narrow band of wavelengths is extracted to use as the probe beam in the OKE-based time-gate configuration. The gate timings and spatial resolution of the time-gated images are also investigated. The low coherence of the probe ensures that the artifacts due to speckles from the laser are reduced to a minimum. To illustrate this a comparison of the time-resolved images of the fuel sprays obtained with this configuration has been made with the images obtained with the collinear, dual color configuration of the optical gate with coherent illumination.

  9. Improving the Coherence Time of a Quantum System via a Coupling to a Short-Lived System

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Yuichiro; Zhu, Xiaobo; Kakuyanagi, Kosuke; Toida, Hiraku; Shimo-Oka, Takaaki; Mizuochi, Norikazu; Nemoto, Kae; Semba, Kouichi; Munro, William J.; Yamaguchi, Hiroshi; Saito, Shiro

    2015-03-01

    In this Letter, we propose a counterintuitive use of a hybrid system where the coherence time of a quantum system can be significantly improved by coupling it with a system of a shorter coherence time. Coupling a two-level system with a single nitrogen-vacancy (NV- ) center, a dark state of the NV- center naturally forms after the hybridization. We show that this dark state becomes robust against noise due to the coupling even when the coherence time of the two-level system is much shorter than that of the NV- center. Our proposal opens a new way to use a quantum hybrid system for the realization of robust quantum information processing.

  10. Short time dissolution kinetics of refractory elements Fe, Al, and Ti in Asian outflow-impacted marine aerosols and implications

    NASA Astrophysics Data System (ADS)

    Hsu, Shih-Chieh; Lin, Fei-Jan; Liu, Tsun-Hsien; Lin, Shuen-Hsin; Kao, Shuh-Ji; Tseng, Chun-Mao; Huang, Chao-Hao

    2013-11-01

    A six-step sequential extraction protocol was employed for marine aerosols with varying mixture of dust and pollution particles collected from the East China Sea to study the dissolution kinetics of refractory elements Fe, Al, and Ti (with a focus on Fe) in relation to acidic substances such as sulfate, nitrate, and water-soluble organic carbon. The three elements might be of a natural origin such as Asian dust and/or anthropogenic origins such as coal fly ash and biomass burning; however, this study focused on the dissolution kinetics, instead of their sources. We selected three samples with varying dust loading but close acid loadings for the experiment so that the acidic effect on the aerosol Fe dissolution could be explored as the direct contribution of water-soluble Fe from anthropogenic sources, if any, might be constrained at a relatively constant level among the samples. Extraction was stepwise performed with six steps for total 30 min, and the leaching duration was as short as ten seconds in the first five steps. No saturation was found for the analyzed elements. Two phases of dissolution curves were observed in all interested compositions, which could be explained by an aged aerosol particle model, with an intrinsically insoluble core and weathered surface. The first phase curve approximates the first-order reaction, with considerably high dissolution rates of 6.5-277 ?mol g-1 min-1, indicating the likely existence of an “extremely fast iron pool” that may exist on the weathered surface of aged particles, along with other three pools proposed by Shi et al. (2011). Acid/dust ratio could be a crucial factor that facilitates parameterization of aerosol iron dissolution. Results of this study are useful in improving aerosol iron and other transition element dissolution schemes in atmospheric chemistry models.

  11. Effects of Morning Caffeine’ Ingestion on Mood States, Simple Reaction Time, and Short-Term Maximal Performance on Elite Judoists

    PubMed Central

    Souissi, Makram; Abedelmalek, Salma; Chtourou, Hamdi; Atheymen, Rim; Hakim, Ahmed; Sahnoun, Zouhair

    2012-01-01

    Purpose The purpose of the present study was to evaluate the ergogenic effect of caffeine ingestion on mood state, simple reaction time, and muscle power during the Wingate test recorded in the morning on elite Judoists. Methods Twelve elite judoists (age: 21.08 ± 1.16 years, body mass: 83.75 ± 20.2 kg, height: 1.76 ±6.57 m) participated in this study. Mood states, simple reaction time, and muscle power during the Wingate test were measured during two test sessions at 07:00 h and after placebo or caffeine ingestion (i.e. 5 mg/kg). Plasma concentrations of caffeine were measured before (T0) and 1-h after caffeine’ ingestion (T1) and after the Wingate test (T3). Results Our results revealed an increase of the anxiety and the vigor (P<0.01), a reduction of the simple reaction time (P<0.001) and an improvement of the peak and mean powers during the Wingate test. However, the fatigue index during this test was unaffected by the caffeine ingestion. In addition, plasma concentration of caffeine was significantly higher at T1 in comparison with T0. Conclusions In conclusion, the results of this study suggest that morning caffeine ingestion has ergogenic properties with the potential to benefit performance, increase anxiety and vigor, and decrease the simple reaction time. PMID:23012635

  12. EUROGRAPHICS 2009 / P. Alliez and M. Magnor Short Paper Real-time Vision-based Lateral Drift Correction

    E-print Network

    Pajarola, Renato B.

    and simple solution for the lateral drift problem for vision guided robots by real-time scene analysis. Without an environment-specific calibration of the robot's drive system, we balance the differential drive-adapted behavior based on a regulatory feedback system, e.g. vision, similar to the humans visual and cognitive

  13. We revisit memory hierarchy design viewing memory as an inter-operation communication agent. This perspective leads to

    E-print Network

    Sohi, Guri S.

    Abstract We revisit memory hierarchy design viewing memory as an inter-operation communication agent. This perspective leads to the development of novel methods of performing inter-operation memory structure called the Transient Value Cache (TVC). The TVC captures memory values that are short

  14. Seismic scaling laws revisited

    E-print Network

    Madariaga, Raúl

    15 years: Vr Earthquakes occur as short duration episodes propagating at high shear speeds (Olsen et al, 1997, Peyrat et al, 2001) Slip rate #12; vr A simple shear crack (earthquake) moving dynamics Macroscale Mesoscale MicroscaleSteady state mechanics vr ( 5 km) (>0.5 Hz

  15. Balance functions revisited

    E-print Network

    A. Bialas

    2011-02-11

    The idea of glue clusters, i.e. short-range correlations in the quark-gluon plasma close to freeze-out, is used to estimate the width of balance functions in momentum space. A good agreement is found with the recent measurements of STAR collaboration for central $Au-Au$ collisions.

  16. The Blast Wave Problem Revisited

    NASA Astrophysics Data System (ADS)

    Kassoy, David R.

    2007-11-01

    The Taylor-von Neumann-Sedov solution for a blast wave generated by instantaneous deposition of energy at a point is a paradigm example of rapid energy addition to a compressible gas. The traditional intuitive blast wave model (Barenblatt, Scaling, self-similarity, and intermediate asymptotics, 47-50, Cambridge University Press, 1996) can be reformulated for time resolved dimensional energy deposition (E') into a finite volume V' (initially containing fluid with a relatively small internal energy E0' at a modest initial temperature T0') with systematic asymptotic methods based on a small parameter ?=E0'/E'<<1. The energy deposition occurs on a time scale tH', short compared to the initial acoustic time ta'= l'/a0' (l' is the characteristic length of the finite volume V', a0' is the initial acoustic speed). The large local nondimensional temperature T'/T0'=O(1/?) and speed u'/a0' =O(1/?^1/2) imply a large local acoustic speed and a significant local Mach number Ml=O(1), respectively, such that the kinetic and internal energies are commensurate. The shock Mach number, Ms=(1/?^1/2), is asymptotically large for the strong blast wave. It also follows that the relatively short local acoustic time tal'= l'/a'=?^1/2ta' is commensurate with the energy addition time tH'. The classical similarity solution for point deposition is obtained by seeking variable combinations independent of the vanishingly small artificial length scale l'.

  17. Real-time operating mode with DSSSD detector to search for short correlation ER-alpha chains

    E-print Network

    Yury Tsyganov; Alexander Polyakov

    2015-06-05

    Real-time PC based algorithm is developed for DSSSD detector. Complete fusion nuclear reaction natYb+48Ca->217Th is used to test this algorithm at 48Ca beam. Example of successful application of a former algorithm for resistive strip PIPS detector in 249Bk+48Ca nuclear reaction is presented too. Case of alpha-alpha correlations is also under brief consideration.

  18. Real-time operating mode with DSSSD detector to search for short correlation ER-alpha chains

    E-print Network

    Tsyganov, Yury

    2015-01-01

    Real-time PC based algorithm is developed for DSSSD detector. Complete fusion nuclear reaction natYb+48Ca->217Th is used to test this algorithm at 48Ca beam. Example of successful application of a former algorithm for resistive strip PIPS detector in 249Bk+48Ca nuclear reaction is presented too. Case of alpha-alpha correlations is also under brief consideration.

  19. Comparison of MCNP calculation and measurement of neutron fluence in a channel for short-time irradiation in the LVR-15 reactor

    SciTech Connect

    Lahodova, Z.; Flibor, S.; Klupak, V.; Kucera, J.; Marek, M.; Viererbl, L.

    2006-07-01

    The main purpose of this work was to evaluate the neutron energy distribution in a channel of the LVR-15 reactor used mostly for short-time neutron activation analysis. Twenty types of activation monitors were irradiated in this channel equipped with a pneumatic facility with a transport time of 3.5 s. The activities measured and the corresponding reaction rates were used to determinate the neutron spectrum. The reaction rates were compared with MCNP calculations to confirm the results. The second purpose of this work was to verify our nuclear data library used for the reaction rate calculations. The experiment results were also incorporated into our database system of neutron energy distribution at the reactor core. (authors)

  20. A Short Interspersed Nuclear Element (SINE)-Based Real-Time PCR Approach to Detect and Quantify Porcine Component in Meat Products.

    PubMed

    Zhang, Chi; Fang, Xin; Qiu, Haopu; Li, Ning

    2015-01-01

    Real-time PCR amplification of mitochondria gene could not be used for DNA quantification, and that of single copy DNA did not allow an ideal sensitivity. Moreover, cross-reactions among similar species were commonly observed in the published methods amplifying repetitive sequence, which hindered their further application. The purpose of this study was to establish a short interspersed nuclear element (SINE)-based real-time PCR approach having high specificity for species detection that could be used in DNA quantification. After massive screening of candidate Sus scrofa SINEs, one optimal combination of primers and probe was selected, which had no cross-reaction with other common meat species. LOD of the method was 44 fg DNA/reaction. Further, quantification tests showed this approach was practical in DNA estimation without tissue variance. Thus, this study provided a new tool for qualitative detection of porcine component, which could be promising in the QC of meat products. PMID:26525266

  1. Trends in ostracod distribution and water chemistry in subarctic Canada: Churchill (Manitoba) lakes and ponds revisited

    NASA Astrophysics Data System (ADS)

    Viehberg, F. A.; Côté, G.; Pienitz, R.

    2009-04-01

    Ecosystems change in response to factors such as climate variability, invasions, and natural hazards over a short period of time (IPCC 2007). The individual organism has to react to complete its life cycle and eventually to reproduce successfully. Under extreme conditions the survival of the total population depends thoroughly on the genetic diversity/potential and thus the ability to expand its biogeographical range or to run extinct. The knowledge of the specific plasticity in time is essential to interpret signals of biological proxies in palaeo records. We investigated 13 lakes/ponds in the surrounding of the Churchill Northern Studies Centre (CNSC; 58° 43.989'N, 93° 49.219'W), Churchill, Canada in 1997. 9 years later we revisited the same localities in 2006. In addition, faunistic data of microcrustaceans in the local study area is available from the late 80's (Havel et al 1990 a, b). and further instrumental climate records from Churchill (Manitoba, Canada) are daily filed since 1943 by Environment Canada. Thus we were able to pinpoint local warming trends and changes in the water chemistry from our short term records in the subarctic study area. The microcrustacean fauna change consecutively. e.g., freshwater ostracods adopted to short open water periods during the summer, strong variations of water temperatures in the shallow waters and mostly low ionic contents of the host waters are not present in the current record. References: Havel, J.E., Hebert, P.D.N. and Delorme, L.D., 1990a. Genetics of sexual Ostracoda from a low Arctic site. Journal of Evolutionary Biology, 3: 65-84. Havel, J.E., Hebert, P.D.N. and Delorme, L.D., 1990b. Genotypic diversity of asexual Ostracoda from a low Arctic site. Journal of Evolutionary Biology, 3: 391-410.

  2. Decomposing very rapid crustal displacements observed in the Amundsen Embayment into their instantaneous elastic and short (10-100 yr) time-scale viscoelastic components

    NASA Astrophysics Data System (ADS)

    Barletta, Valentina; Bevis, Michael; Smith, Ben; Wilson, Terry J.; Brown, Abel; Bordoni, Andrea; Willis, Michael; Smalley, Bob; Kendrick, Eric; Konfal, Stephanie; Caccamise, Dana; Aster, Richard; Chaput, Julien; Heeszel, David; Lloyd, Andrew; Wiens, Doug

    2015-04-01

    The Amundsen Embayment sector of West Antarctica is experiencing some of the fastest sustained bedrock uplift rates in the world. These motions, recorded by the Antarctic GPS Network (ANET) are far too rapid to be explained using traditional GIA models, but they cannot be explained purely in terms of the Earth's elastic response to contemporary ice loss. We use 13 years of very high resolution DEM-derived ice mass change fields over the Amundsen sector to compute the elastic signal and remove that from the observed geodetic time series. We obtain a very large residual - up to 5 times larger than the computed elastic response. We hypothesize that this residual signal manifests a short-time-scale viscoelastic response to post- Little Ice Age ice mass changes, including ice losses developed in the last decade or so. Short time-scale, high-rate viscoelastic deformation is plausible in areas underlain by very low mantle viscosities. Low or very low mantle viscosities are expected in this area based on existing heat flow estimates, seismic velocity anomalies, thin crust, and active volcanism, all of which are associated with geologically recent rifting. We estimated a plausible ice history for the last hundred years. We used the actual measurements from 2002 to 2014, and before 2002 we use 25% of present day melting rate, as suggested by published studies. We then simulated the bedrock displacement - both vertical and horizontal - with a spherical compressible viscoelastic Earth model having a low viscosity shallow upper mantle. We show that we can explain most of the signal (amplitude and direction) by using a 50-60 km elastic lithosphere and 1-2 x10^18 Pa s viscosity in the shallow upper mantle.

  3. Dynamic Topography Revisited

    NASA Astrophysics Data System (ADS)

    Moresi, Louis

    2015-04-01

    Dynamic Topography Revisited Dynamic topography is usually considered to be one of the trinity of contributing causes to the Earth's non-hydrostatic topography along with the long-term elastic strength of the lithosphere and isostatic responses to density anomalies within the lithosphere. Dynamic topography, thought of this way, is what is left over when other sources of support have been eliminated. An alternate and explicit definition of dynamic topography is that deflection of the surface which is attributable to creeping viscous flow. The problem with the first definition of dynamic topography is 1) that the lithosphere is almost certainly a visco-elastic / brittle layer with no absolute boundary between flowing and static regions, and 2) the lithosphere is, a thermal / compositional boundary layer in which some buoyancy is attributable to immutable, intrinsic density variations and some is due to thermal anomalies which are coupled to the flow. In each case, it is difficult to draw a sharp line between each contribution to the overall topography. The second definition of dynamic topography does seem cleaner / more precise but it suffers from the problem that it is not measurable in practice. On the other hand, this approach has resulted in a rich literature concerning the analysis of large scale geoid and topography and the relation to buoyancy and mechanical properties of the Earth [e.g. refs 1,2,3] In convection models with viscous, elastic, brittle rheology and compositional buoyancy, however, it is possible to examine how the surface topography (and geoid) are supported and how different ways of interpreting the "observable" fields introduce different biases. This is what we will do. References (a.k.a. homework) [1] Hager, B. H., R. W. Clayton, M. A. Richards, R. P. Comer, and A. M. Dziewonski (1985), Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313(6003), 541-545, doi:10.1038/313541a0. [2] Parsons, B., and S. Daly (1983), The relationship between surface topography, gravity anomalies, and temperature structure of convection, Journal of Geophysical Research: Solid Earth (1978-2012), 88(B2), 1129-1144, doi:10.1029/JB088iB02p01129. [3] Robinson, E. M., B. Parsons, and S. F. Daly (1987), The effect of a shallow low viscosity zone on the apparent compensation of mid-plate swells, Earth and Planetary Science Letters, 82(3-4), 335-348, doi:10.1016/0012-821X(87)90207-X.

  4. A Response to "Time-Limited Service Alternatives: Using Therapeutic Enactment in Open Group Therapy": A Dramatic Effort to Redefine Short-Term and Time-Limited Services

    ERIC Educational Resources Information Center

    Dagley, John C.; Thomas, Chippewa M.

    2008-01-01

    Therapeutic Enactment (TE) groups, as presented in the article, "Time-Limited Service Alternatives: Using Therapeutic Enactment in Open Group Therapy," offer an exciting and promising addition to the types of groups traditionally offered in university counseling centers. The brevity of member participation, the lack of empirical evidence of…

  5. Very short NMR relaxation times of anions in ionic liquids: New pulse sequence to eliminate the acoustic ringing

    NASA Astrophysics Data System (ADS)

    Klimavicius, Vytautas; Gdaniec, Zofia; Balevicius, Vytautas

    2014-11-01

    NMR relaxation processes of anions were studied in two neat imidazolium-based room temperature ionic liquids (RTILs) 1-decyl-3-methyl-imidazolium bromide- and chloride. The spin-lattice and spin-spin relaxations of 81Br and 35Cl nuclei were found to be extremely fast due to very strong quadrupolar interactions. The determined relaxation rates are comparable with those observed in the solids or in some critical organic solute/water/salt systems. In order to eliminate the acoustic ringing of the probe-head during relaxation times measurements the novel pulse sequence has been devised. It is based on the conventional inversion recovery pulse sequence, however, instead of the last 90° pulse the subsequence of three 90° pulses applied along axes to fulfill the phase cycling condition is used. Using this pulse sequence it was possible to measure T1 for both studied nuclei. The viscosity measurements have been carried out and the rotational correlation times were calculated. The effective 35Cl quadrupolar coupling constant was found to be almost one order lower than that for 81Br, i.e. 1.8 MHz and 16.0 MHz, respectively. Taking into account the facts that the ratio of (Q(35Cl)/Q(81Br))2 ? 0.1 and EFG tensors on the anions are quite similar, analogous structural organizations are expected for both RTILs. The observed T1/T2 (1.27-1.44) ratios were found to be not sufficiently high to confirm the presence of long-living (on the time scale of ?10-8 s) mesoscopic structures or heterogeneities in the studied neat ionic liquids.

  6. Reduced complexity of intracranial pressure observed in short time series of intracranial hypertension following traumatic brain injury in adults.

    PubMed

    Soehle, Martin; Gies, Bernadette; Smielewski, Peter; Czosnyka, Marek

    2013-08-01

    Physiological parameters, such as intracranial pressure (ICP), are regulated by interconnected feedback loops, resulting in a complex time course. According to the decomplexification theory, disease is characterised by a loss of feedback loops resulting in a reduced complexity of the time course of physiological parameters. We hypothesized that complexity of the ICP time series is decreased during periods of intracranial hypertension (IHT) following adult traumatic brain injury. In an observational retrospective cohort study, ICP was continuously monitored using intraparenchymally implanted probes and stored using ICM + -software. Periods of IHT (ICP > 25 mmHg for at least 1,024 s), were compared with preceding periods of intracranial normotension (ICP < 20 mmHg) and analysed at 1 s-intervals. ICP data (length = 1,024 s) were normalised (mean = 0, SD = 1) and complexity was estimated using the scaling exponent ? (as derived from detrended fluctuation analysis), sample entropy (SampEn, m = 1, r = 0.2 × SD) and multiscale entropy. 344 episodes were analysed in 22 patients. During IHT (ICP = 31.7 ± 7.8 mmHg, mean ± SD), ? was significantly elevated (? = 1.02 ± 0.22, p < 0.001) and SampEn significantly reduced (SampEn = 1.45 ± 0.46, p = 0.004) as compared to before IHT (ICP = 15.7 ± 3.2 mmHg, ? = 0.81 ± 0.14, SampEn = 1.81 ± 0.24). In addition, MSE revealed a significantly (p < 0.05) decreased entropy at scaling factors ranging from 1 to 10. Both the increase in ? as well as the decrease in SampEn and MSE indicate a loss of ICP complexity. Therefore following traumatic brain injury, periods of IHT seem to be characterised by a decreased complexity of the ICP waveform. PMID:23306818

  7. Short time synthesis of high quality carbon nanotubes with high rates by CVD of methane on continuously emerged iron nanoparticles

    NASA Astrophysics Data System (ADS)

    Bahrami, Behnam; Khodadadi, Abasali; Mortazavi, Yadollah; Esmaieli, Mohamad

    2011-09-01

    We report the variation of yield and quality of carbon nanotubes (CNTs) grown by chemical vapor deposition (CVD) of methane on iron oxide-MgO at 900-1000 °C for 1-60 min. The catalyst was prepared by impregnation of MgO powder with iron nitrate, dried, and calcined at 300 °C. As calcined and unreduced catalyst in quartz reactor was brought to the synthesis temperature in helium flow in a few minutes, and then the flow was switched to methane. The iron oxide was reduced to iron nanoparticles in methane, while the CNTs were growing. TEM micrographs, in accordance with Raman RBM peaks, indicate the formation of mostly single wall carbon nanotubes of about 1.0 nm size. High quality CNTs with IG/ID Raman peak ratio of 14.5 are formed in the first minute of CNTs synthesis with the highest rate. Both the rate and quality of CNTs degrades with increasing CNTs synthesis time. Also CNTs quality sharply declines with temperature in the range of 900-1000 °C, while the CNTs yield passes through a maximum at 950 °C. About the same CNTs lengths are formed for the whole range of the synthesis times. A model of continuous emergence of iron nanoparticle seeds for CNTs synthesis may explain the data. The data can also provide information for continuous production of CNTs in a fluidized bed reactor.

  8. Interaction between Workers during a Short Time Window Is Required for Bacterial Symbiont Transmission in Acromyrmex Leaf-Cutting Ants

    PubMed Central

    Marsh, Sarah E.; Poulsen, Michael; Pinto-Tomás, Adrián; Currie, Cameron R.

    2014-01-01

    Stable associations between partners over time are critical for the evolution of mutualism. Hosts employ a variety of mechanisms to maintain specificity with bacterial associates. Acromyrmex leaf-cutting ants farm a fungal cultivar as their primary nutrient source. These ants also carry a Pseudonocardia Actinobacteria exosymbiont on their bodies that produces antifungal compounds that help inhibit specialized parasites of the ants' fungal garden. Major workers emerge from their pupal cases (eclose) symbiont-free, but exhibit visible Actinobacterial coverage within 14 days post-eclosion. Using subcolony experiments, we investigate exosymbiont transmission within Acromyrmex colonies. We found successful transmission to newly eclosed major workers fostered by major workers with visible Actinobacteria in all cases (100% acquiring, n?=?19). In contrast, newly eclosed major workers reared without exosymbiont-carrying major workers did not acquire visible Actinobacteria (0% acquiring, n?=?73). We further show that the majority of ants exposed to major workers with exosymbionts within 2 hours of eclosion acquired bacteria (60.7% acquiring, n?=?28), while normal acquisition did not occur when exposure occurred later than 2 hours post-eclosion (0% acquiring, n?=?18). Our findings show that transmission of exosymbionts to newly eclosed major workers occurs through interactions with exosymbiont-covered workers within a narrow time window after eclosion. This mode of transmission likely helps ensure the defensive function within colonies, as well as specificity and partner fidelity in the ant-bacterium association. PMID:25058579

  9. Interaction between workers during a short time window is required for bacterial symbiont transmission in Acromyrmex leaf-cutting ants.

    PubMed

    Marsh, Sarah E; Poulsen, Michael; Pinto-Tomás, Adrián; Currie, Cameron R

    2014-01-01

    Stable associations between partners over time are critical for the evolution of mutualism. Hosts employ a variety of mechanisms to maintain specificity with bacterial associates. Acromyrmex leaf-cutting ants farm a fungal cultivar as their primary nutrient source. These ants also carry a Pseudonocardia Actinobacteria exosymbiont on their bodies that produces antifungal compounds that help inhibit specialized parasites of the ants' fungal garden. Major workers emerge from their pupal cases (eclose) symbiont-free, but exhibit visible Actinobacterial coverage within 14 days post-eclosion. Using subcolony experiments, we investigate exosymbiont transmission within Acromyrmex colonies. We found successful transmission to newly eclosed major workers fostered by major workers with visible Actinobacteria in all cases (100% acquiring, n?=?19). In contrast, newly eclosed major workers reared without exosymbiont-carrying major workers did not acquire visible Actinobacteria (0% acquiring, n?=?73). We further show that the majority of ants exposed to major workers with exosymbionts within 2 hours of eclosion acquired bacteria (60.7% acquiring, n?=?28), while normal acquisition did not occur when exposure occurred later than 2 hours post-eclosion (0% acquiring, n?=?18). Our findings show that transmission of exosymbionts to newly eclosed major workers occurs through interactions with exosymbiont-covered workers within a narrow time window after eclosion. This mode of transmission likely helps ensure the defensive function within colonies, as well as specificity and partner fidelity in the ant-bacterium association. PMID:25058579

  10. Promoting healthy timing and spacing of pregnancy with young married women in Northern Nigeria: a short report.

    PubMed

    Lane, Cate; Joof, Yaikah M; Hassan, Aisha Ahmed; Pryor, Shannon

    2012-06-01

    The persistence of early and closely spaced pregnancies in Northern Nigeria contributes to maternal and child morbidity and mortality. A technical working group to WHO recommended that following a birth, a woman should space her next pregnancy by at least 24 months, and following a miscarriage or abortion, a woman space her next pregnancy by at least six months. UNICEF, UNFPA and WHO also recommend that a woman delay her first pregnancy until 18. These recommendations comprise the concept of Healthy Timing and Spacing of Pregnancy. The Extending Service Delivery Project (ESD) partnered with the Federation of Muslim Women Association of Nigeria and religious leaders to educate communities about the benefits of using family planning to practice HTSP in five local government areas. Informal discussions with 148 women and 28 men found high recall of the HTSP recommendations and favorable attitudes toward spacing and family planning although many remain concerned about the side effects of contraceptive methods. PMID:22916558

  11. A one-step short-time synthesis of Ag@SiO2 core-shell nanoparticles.

    PubMed

    Lismont, Marjorie; Páez, Carlos A; Dreesen, Laurent

    2015-06-01

    A performance of shell-thickness precise control in silver-silica coating core-shell nanoparticles is presented. 60nm sized citrate-stabilized silver nanoparticles are directly silica coated using a modified Stöber process. Tetraethyl orthosilicate is used as a silica precursor and ammonium hydroxide as catalyst in an alcoholic solvent to promote the seeded silica growth. By simply varying the synthesis reaction time from 4 to 60min, the silica shell thickness is increased from 5.1nm to 76.4nm. This well-controlled synthesis is then transposed to 40, 80 and 100nm sized silver cores in order to show the independence of the silica shell growth on the nanoparticle core size. Optical properties, i.e. localized surface plasmon resonance, of the produced silver-silica core-shell are also investigated. PMID:25697687

  12. Short Time-Scale Enhancements to the Global Thermosphere Temperature and Nitric Oxide Content Resulting From Ionospheric Joule Heating

    NASA Astrophysics Data System (ADS)

    Weimer, D. R.; Mlynczak, M. G.; Hunt, L. A.; Sutton, E. K.

    2014-12-01

    The total Joule heating in the polar ionosphere can be derived from an empirical model of the electric fields and currents, using input measurements of the solar wind velocity and interplanetary magnetic field (IMF). In the thermosphere, measurements of the neutral density from accelerometers on the CHAMP and GRACE satellites are used to derive exospheric temperatures, showing that enhanced ionospheric energy dissipation produces elevated temperatures with little delay.Using the total ionospheric heating, changes in the global mean exosphere temperature as a function of time can be calculated with a simple differential equation. The results compare very well with the CHAMP and GRACE measurement. A critical part of the calculation is the rate at which the thermosphere cools after the ionospheric heating is reduced. It had been noted previously that events with significant levels of heating subsequently cool at a faster rate, and this cooling was attributed to enhanced nitric oxide emissions. This correlation with nitric oxide has been confirmed with very high correlations with measurements of nitric oxide emissions in the thermosphere, from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. These measurements were used in a recent improvement in the equations that calculate the thermosphere temperature. The global nitric oxide cooling rates are included in this calculation, and the predicted levels of nitric oxide, derived from the ionosphere heating model, match the SABER measurements very well, having correlation coefficients on the order of 0.9.These calculations are used to govern the sorting of measurements CHAMP and GRACE measurements, on the basis of the global temperature enhancements due to Joule heating, as well as various solar indices, and season. Global maps of the exospheric temperature are produced from these sorted data.

  13. Short GRB 130603B: Discovery of a jet break in the optical and radio afterglows, and a mysterious late-time X-ray excess

    SciTech Connect

    Fong, W.; Berger, E.; Margutti, R.; Chornock, R.; Migliori, G.; Zauderer, B. A.; Lunnan, R.; Laskar, T.; Metzger, B. D.; Foley, R. J.; Desch, S. J.; Meech, K. J.; Sonnett, S.; Dickey, C.; Hedlund, A.; Harding, P.

    2014-01-10

    We present radio, optical/NIR, and X-ray observations of the afterglow of the short-duration Swift and Konus-Wind GRB 130603B, and uncover a break in the radio and optical bands at ?0.5 day after the burst, best explained as a jet break with an inferred jet opening angle of ?4°-8°. GRB 130603B is only the third short GRB with a radio afterglow detection to date, and represents the first time that a jet break has been evident in the radio band. We model the temporal evolution of the spectral energy distribution to determine the burst explosion properties and find an isotropic-equivalent kinetic energy of ?(0.6-1.7) × 10{sup 51} erg and a circumburst density of ?5 × 10{sup –3}-30 cm{sup –3}. From the inferred opening angle of GRB 130603B, we calculate beaming-corrected energies of E {sub ?} ? (0.5-2) × 10{sup 49} erg and E {sub K} ? (0.1-1.6) × 10{sup 49} erg. Along with previous measurements and lower limits we find a median opening angle of ?10°. Using the all-sky observed rate of 10 Gpc{sup –3} yr{sup –1}, this implies a true short GRB rate of ?20 yr{sup –1} within 200 Mpc, the Advanced LIGO/VIRGO sensitivity range for neutron star binary mergers. Finally, we uncover evidence for significant excess emission in the X-ray afterglow of GRB 130603B at ? 1 day and conclude that the additional energy component could be due to fall-back accretion or spin-down energy from a magnetar formed following the merger.

  14. Short GRB 130603B: Discovery of a Jet Break in the Optical and Radio Afterglows, and a Mysterious Late-time X-Ray Excess

    NASA Astrophysics Data System (ADS)

    Fong, W.; Berger, E.; Metzger, B. D.; Margutti, R.; Chornock, R.; Migliori, G.; Foley, R. J.; Zauderer, B. A.; Lunnan, R.; Laskar, T.; Desch, S. J.; Meech, K. J.; Sonnett, S.; Dickey, C.; Hedlund, A.; Harding, P.

    2014-01-01

    We present radio, optical/NIR, and X-ray observations of the afterglow of the short-duration Swift and Konus-Wind GRB 130603B, and uncover a break in the radio and optical bands at ?0.5 day after the burst, best explained as a jet break with an inferred jet opening angle of ?4°-8°. GRB 130603B is only the third short GRB with a radio afterglow detection to date, and represents the first time that a jet break has been evident in the radio band. We model the temporal evolution of the spectral energy distribution to determine the burst explosion properties and find an isotropic-equivalent kinetic energy of ?(0.6-1.7) × 1051 erg and a circumburst density of ?5 × 10-3-30 cm-3. From the inferred opening angle of GRB 130603B, we calculate beaming-corrected energies of E ? ? (0.5-2) × 1049 erg and E K ? (0.1-1.6) × 1049 erg. Along with previous measurements and lower limits we find a median opening angle of ?10°. Using the all-sky observed rate of 10 Gpc-3 yr-1, this implies a true short GRB rate of ?20 yr-1 within 200 Mpc, the Advanced LIGO/VIRGO sensitivity range for neutron star binary mergers. Finally, we uncover evidence for significant excess emission in the X-ray afterglow of GRB 130603B at >~ 1 day and conclude that the additional energy component could be due to fall-back accretion or spin-down energy from a magnetar formed following the merger.

  15. Changes in Children’s Perception-Action Tuning over Short Time Scales: Bicycling across Traffic-Filled Intersections in a Virtual Environment

    PubMed Central

    Plumert, Jodie M.; Kearney, Joseph K.; Cremer, James F.; Recker, Kara M.; Strutt, Jonathan

    2010-01-01

    This investigation examined short-term changes in child and adult cyclists’ gap decisions and movement timing in response to general and specific road-crossing experiences. Ten- and 12-year-olds and adults rode a bicycle through a virtual environment with 12 intersections. Participants faced continuous cross traffic and waited for gaps they judged were adequate for crossing. In the control condition, participants encountered randomly ordered gaps ranging from 1.5 to 5 s at all intersections. In the high-density condition, participants encountered high-density intersections sandwiched between sets of control intersections. These high-density intersections were designed to push participants toward taking tighter gaps. Participants in both conditions were more likely to accept 3.5, 4, 4.5, and 5 s gaps during the last than the first set of intersections, whereas participants in the high-density condition were also more likely to accept very tight 3 s gaps at the last than the first set of intersections. Moreover, individuals in the high-density condition who waited less and took shorter gaps during the middle intersections were also more likely to take very tight 3 s gaps during the last intersections. Ten-year-olds in both conditions had more time to spare when they cleared the path of the oncoming car at the last intersections, whereas 12-year-olds and adults showed no change in time to spare across intersections. Discussion focuses on linking short-term change in perceptual-motor functioning to longer-term perceptual-motor development. PMID:20728090

  16. Adaptation Versus Retrieval Trade-Off Revisited: an Analysis of Boundary Conditions

    E-print Network

    Muñoz-Avila, Héctor

    Adaptation Versus Retrieval Trade-Off Revisited: an Analysis of Boundary Conditions Stephen Lee-off between adaptation and retrieval effort traditionally held as a principle in case-based reasoning. This principle states that the time needed for adaptation reduces with the time spent searching for an adequate

  17. Pair Production Constraints on Superluminal Neutrinos Revisited

    SciTech Connect

    Brodsky, Stanley J.; Gardner, Susan; /Kentucky U.

    2012-02-16

    We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can evade the Cohen-Glashow constraint. In summary, any model for which the CG pair production process operates is excluded because such timelike neutrinos would not be detected by OPERA or other experiments. However, a superluminal neutrino which is effectively lightlike with fixed p{sup 2} can evade the Cohen-Glashow constraint because of energy-momentum conservation. The coincidence involved in explaining the SN1987A constraint certainly makes such a picture improbable - but it is still intrinsically possible. The lightlike model is appealing in that it does not violate Lorentz symmetry in particle interactions, although one would expect Hughes-Drever tests to turn up a violation eventually. Other evasions of the CG constraints are also possible; perhaps, e.g., the neutrino takes a 'short cut' through extra dimensions or suffers anomalous acceleration in matter. Irrespective of the OPERA result, Lorentz-violating interactions remain possible, and ongoing experimental investigation of such possibilities should continue.

  18. Time-resolved synchrotron diffraction and theoretical studies of very short-lived photo-induced molecular species

    PubMed Central

    Coppens, Philip; Benedict, Jason; Messerschmidt, Marc; Novozhilova, Irina; Graber, Tim; Chen, Yu-Sheng; Vorontsov, Ivan; Scheins, Stephan; Zheng, Shao-Liang

    2010-01-01

    Definitive experimental results on the geometry of fleeting species are at the time of writing still limited to monochromatic data collection, but methods for modifications of the polychromatic Laue data to increase their accuracy and their suitability for pump–probe experiments have been implemented and are reviewed. In the monochromatic experiments summarized, excited-state conversion percentages are small when neat crystals are used, but are higher when photoactive species are embedded in an inert framework in supramolecular crystals. With polychromatic techniques and increasing source brightness, smaller samples down to tenths of a micrometre or less can be used, increasing homogeneity of exposure and the fractional population of the excited species. Experiments described include a series of transition metal complexes and a fully organic example involving excimer formation. In the final section, experimental findings are compared with those from theoretical calculations on the isolated species. Qualitative agreement is generally obtained, but the theoretical results are strongly dependent on the details of the calculation, indicating the need for further systematic analysis. PMID:20164641

  19. Constraints on long-lived remnants of neutron star binary mergers from late-time radio observations of short duration gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Metzger, Brian D.; Bower, Geoffrey C.

    2014-01-01

    The coalescence of a binary neutron star (NS) system (an `NS merger' or NSM) may in some cases produce a massive NS remnant that is long lived and, potentially, indefinitely stable to gravitational collapse. Such a remnant has been proposed as an explanation for the late-X-ray emission observed following some short-duration gamma-ray bursts (GRBs) and as possible electromagnetic counterparts to the gravitational wave chirp. A stable NS merger remnant necessarily possesses a large rotational energy ?1052 erg, the majority of which is ultimately deposited into the surrounding circumburst medium (CBM) at mildly relativistic velocities. We present Very Large Array radio observations of seven short GRBs, some of which possessed temporally extended X-ray emission, on time-scales of ˜1-3 yr following the initial burst. No radio sources were detected, with typical upper limits ˜0.3 mJy at ? = 1.4 GHz. A basic model for the synchrotron emission from the blast wave is used to constrain the presence of a long-lived NSM remnant in each system. Depending on the GRB, our non-detections translate into upper limits on the CBM density n ? 3 × 10- 2-3 cm-3 required for consistency with the remnant hypothesis. Our upper limits rule out a long-lived remnant in GRB 050724 and 060505, but cannot rule out such a remnant in other systems due to their lower inferred CMB densities based on afterglow modelling or the lack of such constraints.

  20. Application of MCPA herbicide on soils amended with biostimulants: short-time effects on soil biological properties.

    PubMed

    Tejada, Manuel; García-Martínez, Ana M; Gómez, Isidoro; Parrado, Juan

    2010-08-01

    In this paper we studied in the laboratory the effect of MCPA herbicide at a rate of 1.5lha(-1) (manufactures rate recommended) on biological properties of a Plagic Antrosol amended with four biostimulants (WCDS, wheat condensed distillers soluble; PA-HE, hydrolyzed poultry feathers; CGHE, carob germ enzymatic extract; and RB, rice bran extract). Seven hundred grams of soil were mixed with WCDS at a rate of 10%, CGHE at a rate of 4.7%, PA-HE at a rate of 4.3%, and RB at a rate of 4.4%, respectively, in order to applying the same amount of organic matter to the soil (16.38 g organic matter). An unamended polluted and amended non-polluted soil were used as control. For all treatments, the soil ergosterol, dehydrogenase, urease, and phosphatase activities were measured at two incubation times (0 and 60 d). The 16S rDNA-DGGE profiles in all treatments were determined at the beginning and end of the incubation period. The results indicated that at the end of the incubation period and compared with the control soil, the dehydrogenase, urease and phosphatase activities and ergosterol decreased 39.3%, 20%, 15.7% and 56.5%, respectively in the non-organic amended polluted soil. The application of organic matter to unpolluted soil increased the enzymatic activities and ergosterol. However, this stimulation was higher in the soil amended with RB, followed by PA-HE, WCDS and CGHE. The application of herbicide in organic-amended soils decreased the enzymatic activities and ergosterol content. However, this decrease was lower than for the non-amended herbicide polluted soil. Possibly the low molecular weight protein content easily assimilated by soil microorganisms and the adsorption capacity of humic substances are responsible for less inhibition of these enzyme activities and soil ergosterol. The 16S rDNA-DGGE profiles indicated that herbicide did not negatively affect soil bacterial biodiversity. PMID:20510432

  1. Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations

    NASA Astrophysics Data System (ADS)

    Pirk, N.; Mastepanov, M.; Parmentier, F.-J. W.; Lund, M.; Crill, P.; Christensen, T. R.

    2015-09-01

    The closed chamber technique is widely used to measure the exchange of methane (CH4) and carbon dioxide (CO2) from terrestrial ecosystems. There is, however, large uncertainty about which model should be used to calculate the gas flux from the measured gas concentrations. Due to experimental uncertainties the robust linear regression model (first order polynomial) is often applied, even though theoretical considerations of the technique suggest the application of other, curvilinear models. High-resolution automatic chamber systems which sample gas concentrations several hundred times per flux measurement make it possible to resolve the curvilinear behavior and study the information imposed by the natural variability of the temporal concentration changes. We used more than 50 000 such flux measurements of CH4 and CO2 from five field sites located in peat forming wetlands to calculate fluxes with different models. The flux differences from independent linear estimates are generally found to be smaller than the local flux variability on the plot scale. The curvilinear behavior of the gas concentrations within the chamber is strongly influenced by wind driven chamber leakage, and less so by changing gas concentration gradients in the soil during chamber closure. Such physical processes affect both gas species equally, which makes it possible to isolate biochemical processes affecting the gases differently, such as photosynthesis limitation by chamber headspace CO2 concentrations under high levels of incoming solar radiation. We assess the possibility to exploit this effect for a partitioning of the net CO2 flux into photosynthesis and ecosystem respiration and argue that high-resolution automatic chamber measurements could be used for purposes beyond the estimation of the net gas flux.

  2. Biliary complications in liver transplantation: Impact of anastomotic technique and ischemic time on short- and long-term outcome

    PubMed Central

    Kienlein, Stefan; Schoening, Wenzel; Andert, Anne; Kroy, Daniela; Neumann, Ulf Peter; Schmeding, Maximilian

    2015-01-01

    AIM: To elucidate the impact of various donor recipient and transplant factors on the development of biliary complications after liver transplantation. METHODS: We retrospectively reviewed 200 patients of our newly established liver transplantation (LT) program, who received full size liver graft. Biliary reconstruction was performed by side-to-side (SS), end-to-end (EE) anastomosis or hepeaticojejunostomy (HJ). Biliary complications (BC), anastomotic stenosis, bile leak, papillary stenosis, biliary drain complication, ischemic type biliary lesion (ITBL) were evaluated by studying patient records, corresponding radiologic imaging and reports of interventional procedures [e.g., endoscopic retrograde cholangiopancreatography (ERCP)]. Laboratory results included alanine aminotransferase (ALT), gammaglutamyltransferase and direct/indirect bilirubin with focus on the first and fifth postoperative day, six weeks after LT. The routinely employed external bile drain was examined by a routine cholangiography on the fifth postoperative day and six weeks after transplantation as a standard procedure, but also whenever clinically indicated. If necessary, interventional (e.g., ERCP) or surgical therapy was performed. In case of biliary complication, patients were selected, assigned to different complication-groups and subsequently reviewed in detail. To evaluate the patients outcome, we focussed on appearance of postoperative/post-interventional cholangitis, need for rehospitalisation, retransplantation, ITBL or death caused by BC. RESULTS: A total of 200 patients [age: 56 (19-72), alcoholic cirrhosis: n = 64 (32%), hepatocellular carcinoma: n = 40 (20%), acute liver failure: n = 23 (11.5%), cryptogenic cirrhosis: n = 22 (11%), hepatitis B virus /hepatitis C virus cirrhosis: n = 13 (6.5%), primary sclerosing cholangitis: n = 13 (6.5%), others: n = 25 (12.5%) were included. The median follow-up was 27 mo until June 2015. The overall biliary complication rate was 37.5% (n = 75) with anastomotic strictures (AS): n = 38 (19%), bile leak (BL): n = 12 (6%), biliary drain complication: n = 12 (6%); papillary stenosis (PS): n = 7 (3.5%), ITBL: n = 6 (3%). Clinically relevant were only 19% (n = 38). We established a comprehensive classification for AS with four grades according to clinical relevance. The reconstruction techniques [SS: n = 164, EE: n = 18, HJ: n = 18] showed no significant impact on the development of BCs in general (all n < 0.05), whereas in the HJ group significantly less AS were found (P = 0.031). The length of donor intensive care unit stay over 6 d had a significant influence on BC development (P = 0.007, HR = 2.85; 95%CI: 1.33-6.08) in the binary logistic regression model, whereas other reviewed variables had not [warm ischemic time > 45 min (P = 0.543), cold ischemic time > 10 h (P = 0.114), ALT init > 1500 U/L (P = 0.631), bilirubin init > 5 mg/dL (P = 0.595), donor age > 65 (P = 0.244), donor sex (P = 0.068), rescue organ (P = 0.971)]. 13% (n = 10) of BCs had no therapeutic consequences, 36% (n = 27) resulted in repeated lab control, 40% (n = 30) received ERCP and 11% (n = 8) surgical therapy. Fifteen (7.5%) patients developed cholangitis [AS (n = 6), ITBL (n = 5), PS (n = 3), biliary lesion BL (n = 1)]. One patient developed ITBL twelve months after LT and subsequently needed retransplantation. Rehospitalisation rate was 10.5 % (n= 21) [AS (n = 11), ITBL (n = 5), PS (n = 3), BL (n = 1)] with intervention or reinterventional therapy as main reasons. Retransplantation was performed in 5 (2.5%) patients [ITBL (n = 1), acute liver injury (ALI) by organ rejection (n = 3), ALI by occlusion of hepatic artery (n = 1)]. In total 21 (10.5%) patients died within the follow-up period. Out of these, one patient with AS developed severe fatal chologenic sepsis after ERCP. CONCLUSION: In our data biliary reconstruction technique and ischemic times seem to have little impact on the development of BCs. PMID:26722658

  3. The identification of critical fluctuations and phase transitions in short term and coarse-grained time series-a method for the real-time monitoring of human change processes.

    PubMed

    Schiepek, Günter; Strunk, Guido

    2010-03-01

    We introduce two complementary measures for the identification of critical instabilities and fluctuations in natural time series: the degree of fluctuations F and the distribution parameter D. Both are valid measures even of short and coarse-grained data sets, as demonstrated by artificial data from the logistic map (Feigenbaum-Scenario). A comparison is made with the application of the positive Lyapunov exponent to time series and another recently developed complexity measure-the Permutation Entropy. The results justify the application of the measures within computer-based real-time monitoring systems of human change processes. Results from process-outcome research in psychotherapy and functional neuroimaging of psychotherapy processes are provided as examples for the practical and scientific applications of the proposed measures. PMID:20084517

  4. Experimental investigation of high-temperature, short residence-time calcination and sulfation of limestone and dolostone sorbents

    SciTech Connect

    Hu, Naiya; Miller, S.F.; Scaroni, A.W.

    1994-12-31

    Sulfur dioxide emissions from coal-fired utility boilers and furnaces continue to be of significant regulatory concern. One approach to reducing these emissions that has received considerable attention is the injection of dry, pulverized sorbent (limestone or dolostone) into the combustion chamber. This technology has been applied to conventional coal-fired utility boilers and is considered to be a good candidate for use in coal-fired heat engine applications. During the process, the injected limestone or dolostone particles are rapidly heated by the hot combustion gases and calcined by the reactions CaCO{sub 3} {yields} CaO + CO{sub 2} and CaMg(CO{sub 3}){sub 2} {yields} CaO + MgO + 2CO{sub 2}, respectively. The CaO produced then reacts with SO{sub 2} and excess O{sub 2} in the combustion gases to form CaSO{sub 4}. Experimental data on the rates of calcination, sintering and sulfation have been reported by Borgwardt and others. The physical structure of the calcined sorbents has also been investigated and a number of models have been developed describing the calcination and sulfation processes. The primary application of dry sorbent injection is to conventional coal-fired utility boilers. The sorbent particle size used is either small (in the range of 1 to 30 {mu}m) in pulverized coal applications or large (in the range of 0.25 to 1 mm) for fluidized-bed applications. Few investigations have been carried out using 30 to 100 {mu}m particles, which is the size range of interest for coal-fired heat engine applications. This study investigated the calcination and sulfation behavior of three different sorbents (two limestones and one dolostone) in the size range from 37 to 105 {mu}m. The time required for heating and calcination, the effect of the calcination process on sulfation behavior, and the effect of sorbent type on sulfation behavior were of primary interest.

  5. Containment failure time and mode for a low-pressure short-term station blackout in a BWR-4 with Mark-I containment

    SciTech Connect

    Carbajo, J.J.; Greene, S.R. )

    1993-01-01

    This study investigates containment failure time and mode for a low-pressure, short-term station blackout severe accident sequence in a boiling water reactor (BWR-4) with a Mark-I containment. The severe accident analysis code MELCOR, version 1.8.1, was used in these calculations. Other results using the MELCOR/CORBH package and the BWRSAR and CONTAIN codes are also presented and compared to the MELCOR results. The plant analyzed is the Peach Bottom atomic station, a BWR-4 with a Mark-I containment. The automatic depressurization system was used to depressurize the vessel in accordance with the Emergency Procedure Guidelines. Two different variations of the station blackout were studied: one with a dry cavity and the other with a flooded cavity. For the flooded cavity, it is assumed that a control rod drive (CRD) pump becomes operational after vessel failure, and it is used to pump water into the cavity.

  6. Salt-Induced Universal Slowing Down of the Short-Time Self-Diffusion of a Globular Protein in Aqueous Solution.

    PubMed

    Grimaldo, Marco; Roosen-Runge, Felix; Hennig, Marcus; Zanini, Fabio; Zhang, Fajun; Zamponi, Michaela; Jalarvo, Niina; Schreiber, Frank; Seydel, Tilo

    2015-07-01

    The short-time self-diffusion D of the globular model protein bovine serum albumin in aqueous (D2O) solutions has been measured comprehensively as a function of the protein and trivalent salt (YCl3) concentration, noted cp and cs, respectively. We observe that D follows a universal master curve D(cs,cp) = D(cs = 0,cp) g(cs/cp), where D(cs = 0,cp) is the diffusion coefficient in the absence of salt and g(cs/cp) is a scalar function solely depending on the ratio of the salt and protein concentration. This observation is consistent with a universal scaling of the bonding probability in a picture of cluster formation of patchy particles. The finding corroborates the predictive power of the description of proteins as colloids with distinct attractive ion-activated surface patches. PMID:26266736

  7. Strong Poison Revisited

    SciTech Connect

    Prince, R.C.; Gailer, J.; Gunson, D.E.; Turner, R.J.; George, G.N.; Pickering, I.J.

    2009-06-04

    Selenium in the form of selenocysteine plays an essential role in a number of proteins, but its role in non-enzymatic biochemistry is also important. In this short review we discuss the interactions between inorganic selenium, arsenic and mercury under physiological conditions, especially in the presence of glutathione. This chemistry is obviously important in making the arsenic and mercury unavailable for more toxic interactions, but in the process it suggests that a side-effect of chronic arsenic and/or mercury exposure is likely to be functional selenium deficiency.

  8. The Long and the Short of it: On the Nature and Origin of Functional Overlap Between Representations of Space and Time

    PubMed Central

    Srinivasan, Mahesh; Carey, Susan

    2010-01-01

    When we describe time, we often use the language of space (The movie was long; The deadline is approaching). Experiments 1–3 asked whether—as patterns in language suggest—a structural similarity between representations of spatial length and temporal duration is easier to access than one between length and other dimensions of experience, such as loudness. Adult participants were shown pairings of lines of different length with tones of different duration (Experiment 1) or tones of different loudness (Experiment 2). The length of the lines and duration or loudness of the tones was either positively or negatively correlated. Participants were better able to bind particular lengths and durations when they were positively correlated than when they were not, a pattern not observed for pairings of lengths and tone amplitudes, even after controlling for the presence of visual cues to duration in Experiment 1 (Experiment 3). This suggests that representations of length and duration may functionally overlap to a greater extent than representations of length and loudness. Experiments 4 and 5 asked whether experience with and mastery of words like long and short—which can flexibly refer to both space and time—itself creates this privileged relationship. Nine-month-old infants, like adults, were better able to bind representations of particular lengths and durations when these were positively correlated (Experiment 4), and failed to show this pattern for pairings of lengths and tone amplitudes (Experiment 5). We conclude that the functional overlap between representations of length and duration does not result from a metaphoric construction processes mediated by learning to flexibly use words such as long and short. We suggest instead that it may reflect an evolutionary recycling of spatial representations for more general purposes. PMID:20537324

  9. Retention of a 24-hour time memory in Syrian hamsters carrying the 20-hour short circadian period mutation in casein kinase-1? (ck1?tau/tau).

    PubMed

    Cain, Sean W; Yoon, Jeena; Shrestha, Tenjin C; Ralph, Martin R

    2014-10-01

    Circadian rhythmic expression of conditioned place avoidance (CPA) was produced in Syrian hamsters homozygous for the circadian short period mutation, tau. In constant dim red light neither the 20 h endogenous period, nor a 20 h place conditioning schedule eliminated the 24 h modulation of CPA behavior described previously for wild type (wt) hamsters and other species. Tau mutants exhibited a 20 h rhythm superimposed on the 24 h modulation. The 20 h component was removed selectively with lesions of the suprachiasmatic nucleus. Wt animals conditioned on a 20 h schedule did not produce a 20 h rhythm, but still expressed the 24 h modulation. The results show that the context entrainable oscillator (CEO) underlying memory for the timing of an unconditioned stimulus, retains a period of about 24 h regardless of clock gene background (tau mutation) and/or the conditioning schedule (24 vs 20 h). Therefore the CEO responsible for time memory is distinct from the biological clock controlling activity; the underlying circadian molecular mechanisms may differ from the ubiquitous transcription-translation feedback oscillator; and time memory itself is not classically conditioned. PMID:24933476

  10. Symmetry of the gradient profile as second experimental dimension in the short-time expansion of the apparent diffusion coefficient as measured with NMR diffusometry

    NASA Astrophysics Data System (ADS)

    Laun, Frederik Bernd; Kuder, Tristan Anselm; Zong, Fangrong; Hertel, Stefan; Galvosas, Petrik

    2015-10-01

    The time-dependent apparent diffusion coefficient as measured by pulsed gradient NMR can be used to estimate parameters of porous structures including the surface-to-volume ratio and the mean curvature of pores. In this work, the short-time diffusion limit and in particular the influence of the temporal profile of diffusion gradients on the expansion as proposed by Mitra et al. (1993) is investigated. It is shown that flow-compensated waveforms, i.e. those whose first moment is zero, are blind to the term linear in observation time, which is the term that is proportional to mean curvature and surface permeability. A gradient waveform that smoothly interpolates between flow-compensated and bipolar waveform is proposed and the degree of flow-compensation is used as a second experimental dimension. This two-dimensional ansatz is shown to yield an improved precision when characterizing the confining domain. This technique is demonstrated with simulations and in experiments performed with cylindrical capillaries of 100 ?m radius.

  11. Ultra-short echo-time magnetic resonance imaging distinguishes ischemia/reperfusion injury from acute rejection in a mouse lung transplantation model.

    PubMed

    Chuck, Natalie C; Boss, Andreas; Wurnig, Moritz C; Weiger, Markus; Yamada, Yoshito; Jungraithmayr, Wolfgang

    2016-01-01

    To investigate whether lung tissue characterization by ultra-short echo-time (UTE) magnetic resonance imaging (MRI) allows ischemia/reperfusion injury to be distinguished from acute rejection in a mouse lung transplantation model. After orthotopic lung transplantation with 6 mice receiving syngeneic (C57Bl/6) lung transplants and 6 mice receiving allogeneic (BALB/c) transplants, they underwent postoperative imaging using three-dimensional UTE-MRI (echo times TE = 50-5000 ?s) and conventional T2-weighted fast spin-echo imaging. Quantitative T2* values of lung transplant parenchyma and spin density (SD) were compared by region-of-interest analysis. All samples underwent histological and immunohistochemical workup. In the allogeneic group, alveolar infiltration resulting from acute organ rejection was visualized in the UTE sequences. This was reflected by the quantitative measurements of SD and T2* values with higher values in the allogeneic group compared with the syngeneic group and nontransplanted lung at the first time point (24 h postoperative: Tx allogeneic group SD: 2133.9 ± 516; Tx syngeneic group SD: 1648.61 ± 271; P = 0.004; Tx allogeneic group T2*: 1710.16 ± 644 ?s, Tx syngeneic group T2*: 577.16 ± 263 ?s; P = <0.001). Changes caused by acute rejection after lung transplantation can be visualized and characterized using a UTE sequence due to different relaxation properties compared with both syngeneic lung transplants and normal lung tissue. PMID:26339975

  12. Precision calculation of above-threshold multiphoton ionization in intense short-wavelength laser fields: The momentum-space approach and time-dependent generalized pseudospectral method

    SciTech Connect

    Zhou Zhongyuan; Chu, Shih-I

    2011-01-15

    We present an approach in momentum (P) space for the accurate study of multiphoton and above-threshold ionization (ATI) dynamics of atomic systems driven by intense laser fields. In this approach, the electron wave function is calculated by solving the P-space time-dependent Schroedinger equation (TDSE) in a finite P-space volume under a simple zero asymptotic boundary condition. The P-space TDSE is propagated accurately and efficiently by means of the time-dependent generalized pseudospectral method with optimal momentum grid discretization and a split-operator time propagator in the energy representation. The differential ionization probabilities are calculated directly from the continuum-state wave function obtained by projecting the total electron wave function onto the continuum-state subspace using the projection operator constructed by the continuum eigenfunctions of the unperturbed Hamiltonian. As a case study, we apply this approach to the nonperturbative study of the multiphoton and ATI dynamics of a hydrogen atom exposed to intense short-wavelength laser fields. High-resolution photoelectron energy-angular distribution and ATI spectra have been obtained. We find that with the increase of the laser intensity, the photoelectron energy-angular distribution changes from circular to dumbbell shaped and is squeezed along the laser field direction. We also explore the change of the maximum photoelectron energy with laser intensity and strong-field atomic stabilization phenomenon in detail.

  13. Foraging destinations and marine habitat use of short-tailed albatrosses: A multi-scale approach using first-passage time analysis

    USGS Publications Warehouse

    Suryan, R.M.; Sato, F.; Balogh, G.R.; David, Hyrenbach K.; Sievert, P.R.; Ozaki, K.

    2006-01-01

    We used satellite telemetry, remotely sensed data (bathymetry, chlorophyll a (chl a), sea-surface temperature (SST), wind speed) and first-passage time (FPT) analysis to determine the distribution, movement patterns, and habitat associations of short-tailed albatrosses (Phoebastria albatrus) during the non-breeding season, 2002 and 2003. Satellite transmitters were deployed on birds immediately prior to their departure from a breeding colony at Torishima, Japan (n = 11), or at-sea in the Aleutian Islands (n = 3). Tracking durations ranged from 51 to 138 days for a total of 6709 locations after filtering (131 - 808 per bird). FPT (time required to transit a circle of given radius) revealed the location and spatial scale of area-restricted search (ARS) patterns along flight paths. On average, ARS occurred within 70 km radii. Consequently, the fit of the habitat use models increased at spatial scales beyond a 40 km FPT radius (R2 = 0.31) and stabilized for scales of 70 km and larger (R2=0.40- 0.51). At all scales, wind speed, depth or depth gradient, and chl a or chl a gradient had a significant effect on FPT (i.e., residence time). FPT increased within regions of higher gradients of depth and chl a. In contrast, FPT decreased within regions of greater depth and wind speed, with a significant interaction of wind speed and depth at some scales. Sea-surface temperature or its interactions were only significant at large spatial scales (???160 km FPT radius). Albatrosses engaged in ARS activities primarily over the shelf break and slope, including Kuroshio and Oyashio regions off the western subarctic gyre. Occasionally, birds transited the northern boundary of the Kuroshio Extension while in-route to the Aleutian Islands and Bering Sea, but overall spent little time in the western gyre. In the Aleutian Islands, ARS occurred within straits, particularly along the central and western part of the archipelago. In the Bering Sea, ARS occurred along the northern continental shelf break, the Kamchatka Current region, and east of the Commander Islands. Non-breeding short-tailed albatross concentrate foraging in oceanic areas characterized by gradients in topography and water column productivity. This study provides an understanding of the foraging ecology for a highly migratory, imperiled seabird, and confirms the importance of shelf break and slope regions as hot spots for a variety of top marine predators in the North Pacific.

  14. Foraging destinations and marine habitat use of short-tailed albatrosses: A multi-scale approach using first-passage time analysis

    NASA Astrophysics Data System (ADS)

    Suryan, Robert M.; Sato, Fumio; Balogh, Gregory R.; David Hyrenbach, K.; Sievert, Paul R.; Ozaki, Kiyoaki

    2006-02-01

    We used satellite telemetry, remotely sensed data (bathymetry, chlorophyll a (chl a), sea-surface temperature (SST), wind speed) and first-passage time (FPT) analysis to determine the distribution, movement patterns, and habitat associations of short-tailed albatrosses ( Phoebastria albatrus) during the non-breeding season, 2002 and 2003. Satellite transmitters were deployed on birds immediately prior to their departure from a breeding colony at Torishima, Japan ( n=11), or at-sea in the Aleutian Islands ( n=3). Tracking durations ranged from 51 to 138 days for a total of 6709 locations after filtering (131 - 808 per bird). FPT (time required to transit a circle of given radius) revealed the location and spatial scale of area-restricted search (ARS) patterns along flight paths. On average, ARS occurred within 70 km radii. Consequently, the fit of the habitat use models increased at spatial scales beyond a 40 km FPT radius ( R2=0.31) and stabilized for scales of 70 km and larger ( R2=0.40- 0.51). At all scales, wind speed, depth or depth gradient, and chl a or chl a gradient had a significant effect on FPT (i.e., residence time). FPT increased within regions of higher gradients of depth and chl a. In contrast, FPT decreased within regions of greater depth and wind speed, with a significant interaction of wind speed and depth at some scales. Sea-surface temperature or its interactions were only significant at large spatial scales (?160 km FPT radius). Albatrosses engaged in ARS activities primarily over the shelf break and slope, including Kuroshio and Oyashio regions off the western subarctic gyre. Occasionally, birds transited the northern boundary of the Kuroshio Extension while in-route to the Aleutian Islands and Bering Sea, but overall spent little time in the western gyre. In the Aleutian Islands, ARS occurred within straits, particularly along the central and western part of the archipelago. In the Bering Sea, ARS occurred along the northern continental shelf break, the Kamchatka Current region, and east of the Commander Islands. Non-breeding short-tailed albatross concentrate foraging in oceanic areas characterized by gradients in topography and water column productivity. This study provides an understanding of the foraging ecology for a highly migratory, imperiled seabird, and confirms the importance of shelf break and slope regions as hot spots for a variety of top marine predators in the North Pacific.

  15. Nonstationary oscillations in gyrotrons revisited

    SciTech Connect

    Dumbrajs, O.; Kalis, H.

    2015-05-15

    Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. It is known that in the planes of the generalized gyrotron variables: cyclotron resonance mismatch and dimensionless current or cyclotron resonance mismatch and dimensionless interaction length complicated alternating sequences of regions of stationary, periodic, automodulation, and chaotic oscillations exist. In the past, these regions were investigated on the supposition that the transit time of electrons through the interaction space is much shorter than the cavity decay time. This assumption is valid for short and/or high diffraction quality resonators. However, in the case of long and/or low diffraction quality resonators, which are often utilized, this assumption is no longer valid. In such a case, a different mathematical formalism has to be used for studying nonstationary oscillations. One example of such a formalism is described in the present paper.

  16. Recurrence plots revisited

    NASA Astrophysics Data System (ADS)

    Casdagli, M. C.

    1997-09-01

    We show that recurrence plots (RPs) give detailed characterizations of time series generated by dynamical systems driven by slowly varying external forces. For deterministic systems we show that RPs of the time series can be used to reconstruct the RP of the driving force if it varies sufficiently slowly. If the driving force is one-dimensional, its functional form can then be inferred up to an invertible coordinate transformation. The same results hold for stochastic systems if the RP of the time series is suitably averaged and transformed. These results are used to investigate the nonlinear prediction of time series generated by dynamical systems driven by slowly varying external forces. We also consider the problem of detecting a small change in the driving force, and propose a surrogate data technique for assessing statistical significance. Numerically simulated time series and a time series of respiration rates recorded from a subject with sleep apnea are used as illustrative examples.

  17. Secondary laryngeal tuberculosis revisited

    PubMed Central

    Lodha, Jaini V; Sharma, Arpit; Virmani, Nitish; Bihani, Ameya; Dabholkar, Jyoti P

    2015-01-01

    Introduction: Laryngeal tuberculosis is often misdiagnosed and is a highly contagious public health problem. The changing pattern of the clinical involvement of this disease poses a diagnostic challenge. The authors report four cases of laryngeal tuberculosis encountered in a short span of one month. Materials and Methods: All the four patients who presented to us with hoarseness had underlying active lesions in the lung. In spite of that they presented with mainly laryngeal symptoms and a multitude of findings on laryngeal examination. A diagnosis could be established owing to a high index of clinical suspicion, and due consideration given to the chest findings and positive sputum examination. The patients showed an excellent response to antituberculous therapy. Results and Conclusions: This study underlines the varied nature of laryngeal tuberculosis and the importance of addressing the hoarseness of a patient at the earliest, for the prompt diagnosis of this infectious condition.

  18. Real-time Reservoir Operation Based on a Combination of Long-term and Short-term Optimization and Hydrological Ensemble Forecasts

    NASA Astrophysics Data System (ADS)

    Meier, P.; Tilmant, A.; Boucher, M.; Anctil, F.

    2012-12-01

    In a reservoir system, benefits are usually increased if the system is operated in a coordinated manner. However, despite ever increasing computational power available to users, the optimization of a large system of reservoirs and hydropower stations remains a challenge, especially if uncertainties are included. When applying optimization methods, such as stochastic dynamic programming, the size of a problem becomes quickly too large to be solved. This situation is also known as the curse of dimensionality which limits the applicability of SDP to systems involving only two to three reservoirs. The fact that by design most reservoirs serve multiple purposes adds another difficulty when the operation is to be optimized. A method which is able to address the optimization of multi-purpose reservoirs even in large systems is stochastic dual dynamic programming (SDDP). This approximative dynamic programming technique represents the future benefit function with a number of hyperplanes. The SDDP model developed in this study maximizes the expected net benefits associated with the operation of a reservoir system on a midterm horizon (several years, monthly time step). SDDP provides, at each time step, estimates of the marginal water value stored in each reservoir. Reservoir operators, however, are interested in day-to-day decisions. To provide an operational optimization framework tailored for short-term decision support, the SDDP optimization can be coupled with a short-term nonlinear programming optimization using hydrological ensemble forecasts. The short-term objective therefore consists of the total electricity production within the forecast horizon and the total value of water stored in all the reservoirs. Thus, maximizing this objective ensures that a short-term decision does not contradict the strategic planning. This optimization framework is implemented for the Gatineau river basin, a sub-basin of the Ottawa river north of the city of Ottawa. The Gatineau river features two large and three smaller reservoirs. Electricity is produced at four of the five dams. Besides the production of hydropower, the reservoirs are used to mitigate floods and for recreational purposes. The hydrological ensemble forecasts are generated with the HYDROTEL model, using meteorological ensemble forecasts issued by Environment Canada as forcing data. The framework described above is applied on a rolling horizon optimization mode on a period of almost two years from March 2002 to the end of 2003. The autumn of 2003 is characterized by a period of strong rainfall events which eventually led to flooding in parts of the river basin. Results show, that this coupled optimization is able to maximize the power production without neglecting the multiple purposes of the reservoir. While the optimization process itself is relatively straight-forward, taking a decision form the set of optimal policies is not. For each ensemble member of the hydrological forecast an optimal operation policy is obtained. Therefore, a strategy of decision taking has to be developed, which allows the incorporation of the information provided by the ensemble forecast as a whole. Different decision making strategies are presented and assessed.

  19. Restricting night-time eating reduces daily energy intake in healthy young men: a short-term cross-over study.

    PubMed

    LeCheminant, James D; Christenson, Ed; Bailey, Bruce W; Tucker, Larry A

    2013-12-14

    Few experimental data are available to support the notion that reducing night-time eating changes total daily energy intake (EI) or body weight in healthy adults. The present study primarily examined the short-term effect of night eating restriction (NER) on daily EI in healthy young men. It secondarily examined body weight and moods associated with NER. Using a cross-over design, twenty-nine men (20·9 (sd 2·5) years; 24·4 (sd 2·5) kg/m²) initiated a 2-week NER intervention (elimination of EI from 19.00 to 06.00 hours) and a 2-week control condition, counterbalanced and separated by a 1-week washout period. EI and macronutrient intake were assessed using computerised, multiple-pass 24 h food recalls, body weight via a digital scale and mood using the Profile of Mood States survey. Of the twenty-nine participants, twenty-seven (93 %) completed all aspects of the study. During the NER condition, the participants consumed less total energy per d than during the control condition (10 125 v. 11 146 kJ/d; F= 6·41; P= 0·018). During the NER condition, no energy was reported consumed between 19.00 and 06.00 hours; however, during the control condition, the energy intake of participants was 2920 (sd 1347) kJ/d between 19.00 and 06.00 hours. There was a significant difference in weight change between the NER (-0·4 (sd 1·1) kg) and control (+0·6 (sd 0·9) kg) conditions (F= 22·68; P< 0·001). Differences in total mood score or mood subscales between the NER and control conditions were not apparent (P>0·05). These findings provide support for NER decreasing short-term EI in healthy young men. PMID:23702187

  20. Short-time pressure response during the start-up of a constant-rate production of a high pressure gas well

    NASA Astrophysics Data System (ADS)

    Jin, Yan; Chen, Kang Ping; Chen, Mian; Grapsas, Nicholas; Zhang, Fu Xiang

    2011-04-01

    The start-up flow of a constant-rate production of a high pressure gas well is studied, with emphasis on the effect of gas acceleration. Gas acceleration is important in the near wellbore region for a high pressure gas in a high permeability formation. It is shown that when gas acceleration is important, the system of governing equations for the porous media flow becomes hyperbolic. In response to an impulsively imposed mass flow-rate, a steep pressure front is created at the wellbore and it propagates into the formation. This steep pressure front is trailed by large amplitude pressure waves. As they travel away from the wellbore, the pressure front becomes less steep and the amplitude of the trailing waves decreases due to viscous damping. It is found that the pressure drawdown experiences a rapid increase followed by an oscillatory behavior in short times before approaching the classical logarithmic rise regime. The pressure gradient at the wellbore wall can grow to a large magnitude in the early times, which can cause a tensile failure of the rock materials near the wellbore.

  1. Climate-induced variations in lake levels: A mechanism for short-term sea level change during non-glacial times

    SciTech Connect

    Jacobs, D. ); Sahagian, D. . Dept of Geological Sciences)

    1992-01-01

    Variations in insolation due to periodic orbital parameters can cause climatic changes and associated variations in the intensity of monsoonal circulation. This can lead to significant variations in the levels of internally draining lakes on timescales of 10,000 to 100,000 years in regions affected by the monsoon (20,000 years for orbital precession). These variations may be responsible for small scale (few meters) eustatic sea level changes in an ice-free Earth, and may contribute to sea level changes in the presence of ice as well. The authors have estimated the volume of empty present lake basins in the regions of Asia and North Africa influenced by the monsoon. The surface water volume alone of these basins is equivalent to a two meter difference in sea level, but is considerably augmented by groundwater associated with an increase in lake level. The lake variation mechanism for sea level change has its basis in the Quaternary record of climate change and associated explanatory models. However, the argument also applies to earlier, non-glacial periods of geologic time. Clear evidence for the presence of ice in the Triassic is lacking. However, there is evidence for short-term periodic fluctuations of lake levels as well as sea level during that time. These sea level changes, as well as those in the Devonian, Jurassic, and Cretaceous, may be driven by periodic fluctuation in lacustrine and groundwater storage resulting from orbitally forced changes in monsoon intensity, even in the absence of significant glacial ice.

  2. Transfer time and source tracing in the soil - water- -plant system deciphered by the U-and Th-series short-lived nuclides

    NASA Astrophysics Data System (ADS)

    Rihs, S.; Pierret, M.; Chabaux, F.

    2011-12-01

    Because soils form at the critical interface between the lithosphere and the atmosphere, characterization of the dynamics occurring through this compartment represents an important goal for several scientific fields and/or human activities. However, this issue remains a challenge because soils are complex systems, where a continuous evolution of minerals and organic soil constituents occurs in response to interactions with waters and vegetation. This study aims to investigate the relevance of short-lived nuclides of U- and Th-series to quantify the transfer times and scheme of radionuclides through a soil - water - plant ecosystem. Activities of (226Ra), (228Ra) and (228Th), as well as the long-lived (232Th), were measured by TIMS and gamma-spectrometry in the major compartments of a forested soil section, i.e.: solid soil fractions (exchangeable fraction, secondary phases and inherited primary minerals), waters (seepage soil waters and a spring further down the watershed) and vegetation (fine and coarse roots of beech trees, young and mature leaves). The matching of these nuclides half-live to bio-geochemical processes time-scale and the relatively good chemical analogy of radium with calcium make these isotopes especially suitable to investigate either time or mechanism of transfers within a soil-water-plant system. Indeed, the (228Ra/226Ra) isotopic ratios strongly differ in the range of samples, allowing quantifying the source and duration transfers. Analyses of the various solid soil fractions demonstrate a full redistribution of Ra isotopes between the inherited minerals and secondary soil phases. However, the transfer of these isotopes to the seepage water or to the tree roots does not follow a simple and obvious scheme. Both primary and secondary phases show to contribute to the dissolved radium. However, depending on the season, the tree leaves degradation also produces up to 70% of dissolved radium. Immobilization of a large part of this radium occurs within the first 70cm of the soil layer, either by plant uptake, or adsorption/ precipitation in particular soil layers. Consistently, the Ra isotope ratio in the spring water is similar to the inherited primary soil fraction, suggesting a "deep" (i.e. below the shallow 70cm of soil layer) origin of the exported dissolved radium and the short-scale effect of vegetation cycling onto radium transfer. The radium isotopic ratio in the trees roots does not match the soil exchangeable fraction, nor the seepage waters, but rather the bulk soil, suggesting a large and mixed pool of radium for roots uptake. Decay of 228Ra within the various parts of the trees allows calculating a vegetation cycling duration of about 10 years for this nuclide. Finally an unexpected large amount of unsupported 228Th in the tree leaves can only be explained by a preferential migration of the 228Ac (228Th precursor). The very short life of this nuclide allows therefore assessing that such transport from roots and deposition within stem and leaves take place within 30 hours at the most.

  3. EPR before EPR: A 1930 Einstein-Bohr thought Experiment Revisited

    ERIC Educational Resources Information Center

    Nikolic, Hrvoje

    2012-01-01

    In 1930, Einstein argued against the consistency of the time-energy uncertainty relation by discussing a thought experiment involving a measurement of the mass of the box which emitted a photon. Bohr seemingly prevailed over Einstein by arguing that Einstein's own general theory of relativity saves the consistency of quantum mechanics. We revisit

  4. Health risk of chrysotile revisited

    PubMed Central

    Dunnigan, Jacques; Hesterberg, Thomas; Brown, Robert; Velasco, Juan Antonio Legaspi; Barrera, Raúl; Hoskins, John; Gibbs, Allen

    2013-01-01

    This review provides a basis for substantiating both kinetically and pathologically the differences between chrysotile and amphibole asbestos. Chrysotile, which is rapidly attacked by the acid environment of the macrophage, falls apart in the lung into short fibers and particles, while the amphibole asbestos persist creating a response to the fibrous structure of this mineral. Inhalation toxicity studies of chrysotile at non-lung overload conditions demonstrate that the long (>20?µm) fibers are rapidly cleared from the lung, are not translocated to the pleural cavity and do not initiate fibrogenic response. In contrast, long amphibole asbestos fibers persist, are quickly (within 7?d) translocated to the pleural cavity and result in interstitial fibrosis and pleural inflammation. Quantitative reviews of epidemiological studies of mineral fibers have determined the potency of chrysotile and amphibole asbestos for causing lung cancer and mesothelioma in relation to fiber type and have also differentiated between these two minerals. These studies have been reviewed in light of the frequent use of amphibole asbestos. As with other respirable particulates, there is evidence that heavy and prolonged exposure to chrysotile can produce lung cancer. The importance of the present and other similar reviews is that the studies they report show that low exposures to chrysotile do not present a detectable risk to health. Since total dose over time decides the likelihood of disease occurrence and progression, they also suggest that the risk of an adverse outcome may be low with even high exposures experienced over a short duration. PMID:23346982

  5. Belief Update Revisited Jer^ome Lang

    E-print Network

    Lang, Jérôme

    Belief Update Revisited J´er^ome Lang IRIT ­ CNRS / Universit´e Paul Sabatier 31062 Toulouse Cedex of such a taxonomy. A first step is taken towards this direction (for belief revision only) in [Friedman and Halpern

  6. Short Time Impulse Response Function (STIRF) for automatic evaluation of the variation of the dynamic parameters of reinforced concrete framed structures during strong earthquakes.

    NASA Astrophysics Data System (ADS)

    Carlo Ponzo, Felice; Ditommaso, Rocco

    2015-04-01

    This study presents an innovative strategy for automatic evaluation of the variable fundamental frequency and related damping factor of nonlinear structures during strong motion phases. Most of methods for damage detection are based on the assessment of the variations of the dynamic parameters characterizing the monitored structure. A crucial aspect of these methods is the automatic and accurate estimation of both structural eigen-frequencies and related damping factors also during the nonlinear behaviour. A new method, named STIRF (Short-Time Impulse Response Function - STIRF), based on the nonlinear interferometric analysis combined with the Fourier Transform (FT) here is proposed in order to allow scientists and engineers to characterize frequencies and damping variations of a monitored structure. The STIRF approach helps to overcome some limitation derived from the use of techniques based on simple Fourier Transform. These latter techniques provide good results when the response of the monitored system is stationary, but fails when the system exhibits a non-stationary, time-varying behaviour: even non-stationary input, soil-foundation and/or adjacent structures interaction phenomena can show the inadequacy of classic techniques to analysing the nonlinear and/or non-stationary behaviour of structures. In fact, using this kind of approach it is possible to improve some of the existing methods for the automatic damage detection providing stable results also during the strong motion phase. Results are consistent with those expected if compared with other techniques. The main advantage derived from the use of the proposed approach (STIRF) for Structural Health Monitoring is based on the simplicity of the interpretation of the nonlinear variations of the fundamental frequency and the related equivalent viscous damping factor. The proposed methodology has been tested on both numerical and experimental models also using data retrieved from shaking table tests. Based on the results provided in this study, the methodology seems to be able to evaluate fast variations (over time) of dynamic parameters of a generic reinforced concrete framed structure. Further analyses are necessary to better calibrate the length of the moving time-window (in order to minimize the spurious frequency within each Interferometric Response Function evaluated on both weak and strong motion phases) and to verify the possibility to use the STIRF to analyse the nonlinear behaviour of general systems. Acknowledgements This study was partially funded by the Italian Civil Protection Department within the project DPC-RELUIS 2014 - RS4 ''Seismic observatory of structures and health monitoring''. References R. Ditommaso, F.C. Ponzo (2015). Automatic evaluation of the fundamental frequency variations and related damping factor of reinforced concrete framed structures using the Short Time Impulse Response Function (STIRF). Engineering Structures, 82 (2015), 104-112. http://dx.doi.org/10.1016/j.engstruct.2014.10.023.

  7. Stable Magnetic Universes Revisited

    E-print Network

    Tayebeh Tahamtan; Mustafa Halilsoy

    2011-06-29

    A regular class of static, cylindrically symmetric pure magnetic field metrics is rederived in a different metric ansatz in all dimensions. Radial, time dependent perturbations show that for dimensions d>3 such spacetimes are stable at both near r\\approx0 and large radius r\\rightarrow\\infty. In a different gauge these stability analysis and similar results were known beforehand. For d=3, however, simultaneous stability requirement at both, near and far radial distances can not be reconciled for time - dependent perturbations. Restricted, numerical geodesics for neutral particles reveal a confinement around the center in the polar plane. Charged, time-like geodesics for d=4 on the other hand are shown numerically to run toward infinity.

  8. Green Science: Revisiting Recycling

    ERIC Educational Resources Information Center

    Palliser, Janna

    2011-01-01

    Recycling has been around for a long time--people have reused materials and refashioned them into needed items for thousands of years. More recently, war efforts encouraged conservation and reuse of materials, and in the 1970s recycling got its official start when recycling centers were created. Now, curbside recycling programs and recycling…

  9. Ultrasonic Interferometers Revisited

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2007-01-01

    I have been tinkering with ultrasonic transducers once more. In earlier notes I reported on optics-like experiments performed with ultrasonics, described a number of ultrasonic interferometers, and showed how ultrasonic transducers can be used for Fourier analysis. This time I became interested in trying the technique of using two detectors in…

  10. Revisiting Event Horizon Finders

    E-print Network

    Michael I. Cohen; Harald P. Pfeiffer; Mark A. Scheel

    2009-02-14

    Event horizons are the defining physical features of black hole spacetimes, and are of considerable interest in studying black hole dynamics. Here, we reconsider three techniques to localise event horizons in numerical spacetimes: integrating geodesics, integrating a surface, and integrating a level-set of surfaces over a volume. We implement the first two techniques and find that straightforward integration of geodesics backward in time to be most robust. We find that the exponential rate of approach of a null surface towards the event horizon of a spinning black hole equals the surface gravity of the black hole. In head-on mergers we are able to track quasi-normal ringing of the merged black hole through seven oscillations, covering a dynamic range of about 10^5. Both at late times (when the final black hole has settled down) and at early times (before the merger), the apparent horizon is found to be an excellent approximation of the event horizon. In the head-on binary black hole merger, only {\\em some} of the future null generators of the horizon are found to start from past null infinity; the others approach the event horizons of the individual black holes at times far before merger.

  11. Fermat's Principle Revisited.

    ERIC Educational Resources Information Center

    Kamat, R. V.

    1991-01-01

    A principle is presented to show that, if the time of passage of light is expressible as a function of discrete variables, one may dispense with the more general method of the calculus of variations. The calculus of variations and the alternative are described. The phenomenon of mirage is discussed. (Author/KR)

  12. Statistical Time-resolved Spectroscopy: A Higher Fraction of Short-period Binaries for Metal-rich F-type Dwarfs in SDSS

    NASA Astrophysics Data System (ADS)

    Hettinger, T.; Badenes, C.; Strader, J.; Bickerton, S. J.; Beers, T. C.

    2015-06-01

    Stellar multiplicity lies at the heart of many problems in modern astrophysics, including the physics of star formation, the observational properties of unresolved stellar populations, and the rates of interacting binaries such as cataclysmic variables, X-ray binaries, and SNe Ia. However, little is known about the stellar multiplicity of field stars in the Milky Way (MW), in particular about the differences in the multiplicity characteristics between metal-rich disk stars and metal-poor halo stars. In this study we perform a statistical analysis of ?14,000 F-type dwarf stars in the MW through time-resolved spectroscopy with the sub-exposures archived in the Sloan Digital Sky Survey. We obtain absolute radial velocity (RV) measurements through template cross-correlation of individual sub-exposures with temporal baselines varying from minutes to years. These sparsely sampled RV curves are analyzed using Markov chain Monte Carlo techniques to constrain the very short-period binary fraction for field F-type stars in the MW. Metal-rich disk stars were found to be 30% more likely to have companions with periods shorter than 12 days than metal-poor halo stars.

  13. Using recorded sound spectra profile as input data for real-time short-term urban road-traffic-flow estimation.

    PubMed

    Torija, Antonio J; Ruiz, Diego P

    2012-10-01

    Road traffic has a heavy impact on the urban sound environment, constituting the main source of noise and widely dominating its spectral composition. In this context, our research investigates the use of recorded sound spectra as input data for the development of real-time short-term road traffic flow estimation models. For this, a series of models based on the use of Multilayer Perceptron Neural Networks, multiple linear regression, and the Fisher linear discriminant were implemented to estimate road traffic flow as well as to classify it according to the composition of heavy vehicles and motorcycles/mopeds. In view of the results, the use of the 50-400 Hz and 1-2.5 kHz frequency ranges as input variables in multilayer perceptron-based models successfully estimated urban road traffic flow with an average percentage of explained variance equal to 86%, while the classification of the urban road traffic flow gave an average success rate of 96.1%. PMID:22858535

  14. Time-course study of different innate immune mediators produced by UV-irradiated skin: comparative effects of short and daily versus a single harmful UV exposure.

    PubMed

    Cela, Eliana M; Friedrich, Adrian; Paz, Mariela L; Vanzulli, Silvia I; Leoni, Juliana; González Maglio, Daniel H

    2015-05-01

    The modulatory effects of solar UV radiation on the immune system have been widely studied. As the skin is the main target of UV radiation, our purpose was to compare the impact on skin innate immunity of two contrasting ways to be exposed to sunlight. Hairless mice were UV irradiated with a single high UV dose simulating a harmful exposure, or with repetitive low UV doses simulating short occasional daily exposures. Skin samples were taken at different times after UV irradiation to evaluate skin histology, inflammatory cell recruitment, epidermal T-cell population and the mitochondrial function of epidermal cells. The transcriptional profiles of pro-inflammatory cytokines, chemokines, antimicrobial peptides and Toll-like receptors were evaluated by RT-PCR and ELISA in tissue homogenates. Finally, a lymphangiography was performed to assess modification in the lymphatic vessel system. A single high UV dose produces a deep inflammatory state characterized by the production of pro-inflammatory cytokines and chemokines that, in turn, induces the recruitment of neutrophils and macrophages into the irradiated area. On the other hand, repetitive low UV doses drive the skin to a photo-induced alert state in which there is no sign of inflammation, but the epithelium undergoes changes in thickness, the lymphatic circulation increases, and the transcription of antimicrobial peptides is induced. PMID:25438991

  15. Statistical Time-Resolved Spectroscopy: A higher fraction of short-period binaries for metal-rich F-type dwarfs in SDSS

    E-print Network

    Hettinger, T; Strader, J; Bickerton, S J; Beers, T C

    2015-01-01

    Stellar multiplicity lies at the heart of many problems in modern astrophysics, including the physics of star formation, the observational properties of unresolved stellar populations, and the rates of interacting binaries such as cataclysmic variables, X-ray binaries, and Type Ia supernovae. However, little is known about the stellar multiplicity of field stars in the Milky Way, in particular about the differences in the multiplicity characteristics between metal-rich disk stars and metal-poor halo stars. In this study we perform a statistical analysis of ~15,000 F-type dwarf stars in the Milky Way through time-resolved spectroscopy with the sub-exposures archived in the Sloan Digital Sky Survey. We obtain absolute radial velocity measurements through template cross-correlation of individual sub-exposures with temporal baselines varying from minutes to years. These sparsely sampled radial velocity curves are analyzed using Markov chain Monte Carlo techniques to constrain the very short-period binary fraction...

  16. Distant future of the Sun and Earth revisited

    NASA Astrophysics Data System (ADS)

    Schröder, K.-P.; Connon Smith, Robert

    2008-05-01

    We revisit the distant future of the Sun and the Solar system, based on stellar models computed with a thoroughly tested evolution code. For the solar giant stages, mass loss by the cool (but not dust-driven) wind is considered in detail. Using the new and well-calibrated mass-loss formula of Schröder & Cuntz, we find that the mass lost by the Sun as a red giant branch (RGB) giant (0.332Msolar, 7.59 Gyr from now) potentially gives planet Earth a significant orbital expansion, inversely proportional to the remaining solar mass. According to these solar evolution models, the closest encounter of planet Earth with the solar cool giant photosphere will occur during the tip-RGB phase. During this critical episode, for each time-step of the evolution model, we consider the loss of orbital angular momentum suffered by planet Earth from tidal interaction with the giant Sun, as well as dynamical drag in the lower chromosphere. As a result of this, we find that planet Earth will not be able to escape engulfment, despite the positive effect of solar mass loss. In order to survive the solar tip-RGB phase, any hypothetical planet would require a present-day minimum orbital radius of about 1.15 au. The latter result may help to estimate the chances of finding planets around white dwarfs. Furthermore, our solar evolution models with detailed mass-loss description predict that the resulting tip-AGB (asymptotic giant branch) giant will not reach its tip-RGB size. Compared to other solar evolution models, the main reason is the more significant amount of mass lost already in the RGB phase of the Sun. Hence, the tip-AGB luminosity will come short of driving a final, dust-driven superwind, and there will be no regular solar planetary nebula (PN). The tip-AGB is marked by a last thermal pulse, and the final mass loss of the giant may produce a circumstellar (CS) shell similar to, but rather smaller than, that of the peculiar PN IC 2149 with an estimated total CS shell mass of just a few hundredths of a solar mass.

  17. Short-term sleep deprivation with nocturnal light exposure alters time-dependent glucagon-like peptide-1 and insulin secretion in male volunteers.

    PubMed

    Gil-Lozano, Manuel; Hunter, Paola M; Behan, Lucy-Ann; Gladanac, Bojana; Casper, Robert F; Brubaker, Patricia L

    2016-01-01

    The intestinal L cell is the principal source of glucagon-like peptide-1 (GLP-1), a major determinant of insulin release. Because GLP-1 secretion is regulated in a circadian manner in rodents, we investigated whether the activity of the human L cell is also time sensitive. Rhythmic fluctuations in the mRNA levels of canonical clock genes were found in the human NCI-H716 L cell model, which also showed a time-dependent pattern in their response to well-established secretagogues. A diurnal variation in GLP-1 responses to identical meals (850 kcal), served 12 h apart in the normal dark (2300) and light (1100) periods, was also observed in male volunteers maintained under standard sleep and light conditions. These findings suggest the existence of a daily pattern of activity in the human L cell. Moreover, we separately tested the short-term effects of sleep deprivation and nocturnal light exposure on basal and postprandial GLP-1, insulin, and glucose levels in the same volunteers. Sleep deprivation with nocturnal light exposure disrupted the melatonin and cortisol profiles and increased insulin resistance. Moreover, it also induced profound derangements in GLP-1 and insulin responses such that postprandial GLP-1 and insulin levels were markedly elevated and the normal variation in GLP-1 responses was abrogated. These alterations were not observed in sleep-deprived participants maintained under dark conditions, indicating a direct effect of light on the mechanisms that regulate glucose homeostasis. Accordingly, the metabolic abnormalities known to occur in shift workers may be related to the effects of irregular light-dark cycles on these glucoregulatory pathways. PMID:26530153

  18. Hypoxia-Inducible Factor ? and Hif-prolyl Hydroxylase Characterization and Gene Expression in Short-Time Air-Exposed Mytilus galloprovincialis.

    PubMed

    Giannetto, Alessia; Maisano, Maria; Cappello, Tiziana; Oliva, Sabrina; Parrino, Vincenzo; Natalotto, Antonino; De Marco, Giuseppe; Barberi, Chiara; Romeo, Orazio; Mauceri, Angela; Fasulo, Salvatore

    2015-12-01

    Aquatic organisms experience environmental hypoxia as a result of eutrophication and naturally occurring tidal cycles. Mytilus galloprovincialis, being an anoxic/hypoxic-tolerant bivalve, provides an excellent model to investigate the molecular mechanisms regulating oxygen sensing. Across the animal kingdom, inadequacy in oxygen supply is signalled predominantly by hypoxia-inducible factors (HIF) and Hif-prolyl hydroxylases (PHD). In this study, hif-? 5'-end and partial phd mRNA sequences from M. galloprovincialis were obtained. Phylogenetic and molecular characterization of both HIF-? and PHD putative proteins showed shared key features with the respective orthologues from animals strongly suggesting their crucial involvement in the highly conserved oxygen sensing pathway. Both transcripts displayed a tissue-specific distribution with prominent expression in gills. Quantitative gene expression analysis of hif-? and phd mRNAs from gills of M. galloprovincialis demonstrated that both these key sensors are transcriptionally modulated by oxygen availability during the short-time air exposure and subsequent re-oxygenation treatments proving that they are critical players of oxygen-sensing mechanisms in mussels. Remarkably, hif-? gene expression showed a prompt and transient response suggesting the precocious implication of this transcription factor in the early phase of the adaptive response to hypoxia in Mytilus. HIF-? and PHD proteins were modulated in a time-dependent manner with trends comparable to mRNA expression patterns, thus suggesting a central role of their transcriptional regulation in the hypoxia tolerance strategies in marine bivalves. These results provide molecular information about the effects of oxygen deficiency and identify hypoxia-responsive biomarker genes in mussels applicable in ecotoxicological studies of natural marine areas. PMID:26277612

  19. Dark matter relic density in scalar-tensor gravity revisited

    NASA Astrophysics Data System (ADS)

    Meehan, Michael T.; Whittingham, Ian B.

    2015-12-01

    We revisit the calculation of dark matter relic abundances in scalar-tensor gravity using a generic form A(varphi*) = e?varphi*2/2 for the coupling between the scalar field varphi* and the metric, for which detailed Big Bang Nucleosynthesis constraints are available. We find that BBN constraints restrict the modified expansion rate in these models to be almost degenerate with the standard expansion history at the time of dark matter decoupling. In this case the maximum level of enhancement of the dark matter relic density was found to be a factor of ~ 3, several orders of magnitude below that found in previous investigations.

  20. Closed-set-based Discovery of Representative Association Rules Revisited

    E-print Network

    Balcázar, José L

    2010-01-01

    The output of an association rule miner is often huge in practice. This is why several concise lossless representations have been proposed, such as the "essential" or "representative" rules. We revisit the algorithm given by Kryszkiewicz (Int. Symp. Intelligent Data Analysis 2001, Springer-Verlag LNCS 2189, 350-359) for mining representative rules. We show that its output is sometimes incomplete, due to an oversight in its mathematical validation, and we propose an alternative complete generator that works within only slightly larger running times.

  1. Median artery revisited.

    PubMed

    Rodríguez-Niedenführ, M; Sañudo, J R; Vázquez, T; Nearn, L; Logan, B; Parkin, I

    1999-07-01

    This study confirms that the median artery may persist in adult life in 2 different patterns, palmar and antebrachial, based on their vascular territory. The palmar type, which represents the embryonic pattern, is large, long and reaches the palm. The antebrachial type,which represents a partial regression of the embryonic artery is slender, short, and terminates before reaching the wrist. These 2 arterial patterns appear with a different incidence. The palmar pattern was studied in the whole sample (120 cadavers) and had an incidence of 20%, being more frequent in females than in males (1.3:1), occurring unilaterally more often than bilaterally (4:1) and slightly more frequently on the right than on the left (1.1:1). The antebrachial pattern was studied in only 79 cadavers and had an incidence of 76%, being more frequent in females than in males (1.6:1); it was commoner unilaterally than bilaterally (1.5:1) and was again slightly more prevalent on the right than on the left (1.2:1). The origin of the median artery was variable in both patterns. The palmar type most frequently arose from the caudal angle between the ulnar artery and its common interosseous trunk (59%). The antebrachial pattern most frequently originated from the anterior interosseous artery (55%). Other origins, for both patterns, were from the ulnar artery or from the common interosseous trunk. The median artery in the antebrachial pattern terminated in the upper third (74%) or in the distal third of the forearm (26%). However, the palmar pattern ended as the 1st, 2nd or 1st and 2nd common digital arteries (65%) or joined the superficial palmar arch (35%). The median artery passed either anterior (67%) or posterior (25%) to the anterior interosseous nerve. It pierced the median nerve in the upper third of the forearm in 41% of cases with the palmar pattern and in none of the antebrachial cases. In 1 case the artery pierced both the anterior interosseous and median nerves. PMID:10473293

  2. How clonal are Neisseria species? The epidemic clonality model revisited

    PubMed Central

    Tibayrenc, Michel; Ayala, Francisco J.

    2015-01-01

    The three species Neisseria meningitidis, Neisseria gonorrheae, and Neisseria lactamica are often regarded as highly recombining bacteria. N. meningitidis has been considered a paradigmatic case of the “semiclonal model” or of “epidemic clonality,” demonstrating occasional bouts of clonal propagation in an otherwise recombining species. In this model, occasional clonality generates linkage disequilibrium in the short term. In the long run, however, the effects of clonality are countered by recombination. We show that many data are at odds with this proposal and that N. meningitidis fits the criteria that we have proposed for predominant clonal evolution (PCE). We point out that (i) the proposed way to distinguish epidemic clonality from PCE may be faulty and (ii) the evidence of deep phylogenies by microarrays and whole-genome sequencing is at odds with the predictions of the semiclonal model. Last, we revisit the species status of N. meningitidis, N. gonorrheae, and N. lactamica in the light of the PCE model. PMID:26195766

  3. How clonal are Neisseria species? The epidemic clonality model revisited.

    PubMed

    Tibayrenc, Michel; Ayala, Francisco J

    2015-07-21

    The three species Neisseria meningitidis, Neisseria gonorrheae, and Neisseria lactamica are often regarded as highly recombining bacteria. N. meningitidis has been considered a paradigmatic case of the "semiclonal model" or of "epidemic clonality," demonstrating occasional bouts of clonal propagation in an otherwise recombining species. In this model, occasional clonality generates linkage disequilibrium in the short term. In the long run, however, the effects of clonality are countered by recombination. We show that many data are at odds with this proposal and that N. meningitidis fits the criteria that we have proposed for predominant clonal evolution (PCE). We point out that (i) the proposed way to distinguish epidemic clonality from PCE may be faulty and (ii) the evidence of deep phylogenies by microarrays and whole-genome sequencing is at odds with the predictions of the semiclonal model. Last, we revisit the species status of N. meningitidis, N. gonorrheae, and N. lactamica in the light of the PCE model. PMID:26195766

  4. Dimensional analysis revisited.

    PubMed

    Günther, Bruno; Morgado, Enrique

    2003-01-01

    The applicability of dimensional analysis (DA) is discussed in relation to the metabolic scaling laws. The evolution of different theories of biological similarity has shown that the calculated reduced exponents (b) of Huxley's allometric equation are closely correlated with the numerical values obtained from the statistical analysis of empirical data. Body mass and body weight are not equivalent as biological reference systems, since in accordance to Newton's second law, the former has a dimension of a mass, while the latter should be dimensionally considered as a force (W = MLT-2). This distinction affects the coefficients of the mass exponent (alpha). This difference is of paramount importance in microgravity conditions (spaceflight) and of buoyancy during the fetal life in mammals. Furthermore, the coefficients (beta) of the length dimension, and (gamma) of the time dimension do not vary when mass or weight are utilized as reference systems. Consequently, the "specific metabolic time," that results from the ratio of basal oxygen consumption and body mass or body weight yields the "biological meaning" of the time dimension, which is of fractal nature. PMID:14631872

  5. Reframing Academic Literacy: Re-Examining a Short-Course for "Disadvantaged" Tertiary Students

    ERIC Educational Resources Information Center

    Henderson, Robyn; Hirst, Elizabeth

    2007-01-01

    This paper revisits a successful short-course in academic literacy that was conducted for 50 "disadvantaged" students enrolled in the first year of an education degree at an Australian regional university (see Hirst, Henderson, Allan, Bode & Kocatepe, 2004). Based on a sociocultural approach to learning and drawing on a conceptualisation of…

  6. GLOBAL STAR FORMATION REVISITED

    SciTech Connect

    Silk, Joseph; Norman, Colin E-mail: norman@stsci.edu

    2009-07-20

    A general treatment of disk star formation is developed from a dissipative multiphase model, with the dominant dissipation due to cloud collisions. The Schmidt-Kennicutt (SK) law emerges naturally for star-forming disks and starbursts. We predict that there should be an inverse correlation between Tully-Fisher law and SK law residuals. The model is extended to include a multiphase treatment of supernova feedback that leads to a turbulent pressure-regulated generalization of the star formation law and is applicable to gas-rich starbursts. Enhanced pressure, as expected in merger-induced star formation, enhances star formation efficiency. An upper limit is derived for the disk star formation rate in starbursts that depends on the ratio of global ISM to cloud pressures. We extend these considerations to the case where the interstellar gas pressure in the inner galaxy is dominated by outflows from a central active galactic nucleus (AGN). During massive spheroid formation, AGN-driven winds trigger star formation, resulting in enhanced supernova feedback and outflows. The outflows are comparable to the AGN-boosted star formation rate and saturate in the super-Eddington limit. Downsizing of both SMBH and spheroids is a consequence of AGN-driven positive feedback. Bondi accretion feeds the central black hole with a specific accretion rate that is proportional to the black hole mass. AGN-enhanced star formation is mediated by turbulent pressure and relates spheroid star formation rate to black hole accretion rate. The relation between black hole mass and spheroid velocity dispersion has a coefficient (Salpeter time to gas consumption time ratio) that provides an arrow of time. Highly efficient, AGN-boosted star formation can occur at high redshift.

  7. The super collider revisited

    SciTech Connect

    Hussein, M.S.; Pato, M.P. )

    1992-05-20

    In this paper, the authors suggest a revised version of the Superconducting Super Collider (SSC) that employs the planned SSC first stage machine as an injector of 0.5 TeV protons into a power laser accelerator. The recently developed Non-linear Amplification of Inverse Bremsstrahlung Acceleration (NAIBA) concept dictates the scenario of the next stage of acceleration. Post Star Wars lasers, available at several laboratories, can be used for the purpose. The 40 TeV CM energy, a target of the SSC, can be obtained with a new machine which can be 20 times smaller than the planned SSC.

  8. Ancient deforestation revisited.

    PubMed

    Hughes, J Donald

    2011-01-01

    The image of the classical Mediterranean environment of the Greeks and Romans had a formative influence on the art, literature, and historical perception of modern Europe and America. How closely does is this image congruent with the ancient environment as it in reality existed? In particular, how forested was the ancient Mediterranean world, was there deforestation, and if so, what were its effects? The consensus of historians, geographers, and other scholars from the mid-nineteenth century through the first three quarters of the twentieth century was that human activities had depleted the forests to a major extent and caused severe erosion. My research confirmed this general picture. Since then, revisionist historians have questioned these conclusions, maintaining instead that little environmental damage was done to forests and soils in ancient Greco-Roman times. In a reconsideration of the question, this paper looks at recent scientific work providing proxy evidence for the condition of forests at various times in ancient history. I look at three scientific methodologies, namely anthracology, palynology, and computer modeling. Each of these avenues of research offers support for the concept of forest change, both in abundance and species composition, and episodes of deforestation and erosion, and confirms my earlier work. PMID:20669043

  9. Cosmological Perturbation Theory Revisited

    E-print Network

    Claes Uggla; John Wainwright

    2011-12-05

    Increasingly accurate observations are driving theoretical cosmology toward the use of more sophisticated descriptions of matter and the study of nonlinear perturbations of FL cosmologies, whose governing equations are notoriously complicated. Our goal in this paper is to formulate the governing equations for linear perturbation theory in a particularly simple and concise form in order to facilitate the extension to nonlinear perturbations. Our approach has several novel features. We show that the use of so-called intrinsic gauge invariants has two advantages. It naturally leads to: (i) a physically motivated choice of a gauge invariant associated with the matter density, and (ii) two distinct and complementary ways of formulating the evolution equations for scalar perturbations, associated with the work of Bardeen and of Kodama and Sasaki. In the first case the perturbed Einstein tensor gives rise to a second order (in time) linear differential operator, and in the second case to a pair of coupled first order (in time) linear differential operators. These operators are of fundamental importance in cosmological perturbation theory, since they provide the leading order terms in the governing equations for nonlinear perturbations.

  10. Classical Diamagnetism Revisited

    NASA Astrophysics Data System (ADS)

    Saha, Arnab; Lahiri, Sourabh; Jayannavar, A. M.

    The well-known Bohr-van Leeuwen Theorem states that the orbital diamagnetism of classical charged particles is identically zero in equilibrium. However, results based on real space-time approach using the classical Langevin equation predicts non-zero diamagnetism for classical unbounded (finite or infinite) systems. Here we show that the recently discovered Fluctuation Theorems, namely, the Jarzynski Equality or the Crooks Fluctuation Theorem surprisingly predicts a free energy that depends on magnetic field as well as on the friction coefficient, in outright contradiction to the canonical equilibrium results. However, in the cases where the Langevin approach is consistent with the equilibrium results, the Fluctuation Theorems lead to results in conformity with equilibrium statistical mechanics. The latter is demonstrated analytically through a simple example that has been discussed recently.

  11. Cleckley's psychopaths: Revisited.

    PubMed

    Crego, Cristina; Widiger, Thomas A

    2016-01-01

    The most influential figure in the study of psychopathy is Hervey Cleckley, the author of the widely cited text, "The Mask of Sanity" (Cleckley, 1941, 1955). Researchers often refer to Cleckley when disputing what should belong within a conceptualization or assessment of psychopathy, at times disagreeing as to what Cleckley meant or intended. Cleckley though included within his text 15 detailed case studies of prototypic psychopaths. The current study was the first to provide systematic ratings of these 15 cases, including ratings with respect to (a) the 16 Cleckley criteria (e.g., anxiousness and inadequately motivated antisocial behavior), (b) 33 additional traits included within or considered for more recently developed measures and models of psychopathy (e.g., boldness, fearlessness, disobliged, cruelty, and aggression), and (c) 30 traits of the 5-factor model of general personality. The results are discussed with respect to implications for both historic and current models of psychopathy. (PsycINFO Database Record PMID:26618655

  12. Cosmological Perturbation Theory Revisited

    E-print Network

    Uggla, Claes

    2011-01-01

    Increasingly accurate observations are driving theoretical cosmology toward the use of more sophisticated descriptions of matter and the study of nonlinear perturbations of FL cosmologies, whose governing equations are notoriously complicated. Our goal in this paper is to formulate the governing equations for linear perturbation theory in a particularly simple and concise form in order to facilitate the extension to nonlinear perturbations. Our approach has several novel features. We show that the use of so-called intrinsic gauge invariants has two advantages. It naturally leads to: (i) a physically motivated choice of a gauge invariant associated with the matter density, and (ii) two distinct and complementary ways of formulating the evolution equations for scalar perturbations, associated with the work of Bardeen and of Kodama and Sasaki. In the first case the perturbed Einstein tensor gives rise to a second order (in time) linear differential operator, and in the second case to a pair of coupled first orde...

  13. OH + HBr reaction revisited

    SciTech Connect

    Ravishankara, A.R.; Wine, P.H.; Wells, J.R.

    1985-07-01

    Variable-temperature measurements of the rate coefficient /k(1)/ for the reaction OH + HBr yield Br + H2O are presented. The measurements are verified by two techniques: one involved a 266-nm pulsed-laser photolysis of O3/H2O/HBr/He mixtures in conjunction with time-resolved resonance fluorescence detection of OH, the second comprised pulsed laser-induced fluorescence detection of OH following 248-nm pulsed-laser photolysis of H2O2/HBr/Ar mixtures. It is reported that k(1) = (11.9 + or -1.4 x 10 to the -12th (cu cm)/(molecule)(s) independent of temperature. The measurements are compared with other available results. 6 references.

  14. Revisiting Classical Diamagnetism: A Surprise of Physics

    NASA Astrophysics Data System (ADS)

    Kumar, Narendra; Krishnamurthy, Vijay Kumar

    2009-03-01

    The Classic Bohr-van Leeuwen (BvL) theorem states that the orbital diamagnetism of a classical system of charged particles in thermal equilibrium is identically zero. This theorem is universally accepted and has entered textbooks. Physically, the theorem derives from the exact cancellation of the orbital diamagnetic moment associated with the completed cyclotron orbits of the charged particles by the paramagnetic moment subtended by the incomplete orbits skipping the boundary cuspidally in the opposite sense. In this work we have revisited the problem of this crucial but subtle role of the boundary by considering the case of a finite but unbounded system, namely that of a charged particle moving on a sphere in the presence of an externally applied magnetic field. The orbital moment calculated on the basis of the classical Langevin equation in the infinite time limit now indeed turns out to be non-zero, and has the diamagnetic sign. This violates the BvL theorem as stated in the literature. To the best of our knowledge, this is the first report of non-zero classical diamagnetism. It is explicitly owing to the above avoided cancellation. We also present possible experimental realization of the predicted classical diamagnetism.

  15. Meta-analysis in clinical trials revisited.

    PubMed

    DerSimonian, Rebecca; Laird, Nan

    2015-11-01

    In this paper, we revisit a 1986 article we published in this Journal, Meta-Analysis in Clinical Trials, where we introduced a random-effects model to summarize the evidence about treatment efficacy from a number of related clinical trials. Because of its simplicity and ease of implementation, our approach has been widely used (with more than 12,000 citations to date) and the "DerSimonian and Laird method" is now often referred to as the 'standard approach' or a 'popular' method for meta-analysis in medical and clinical research. The method is especially useful for providing an overall effect estimate and for characterizing the heterogeneity of effects across a series of studies. Here, we review the background that led to the original 1986 article, briefly describe the random-effects approach for meta-analysis, explore its use in various settings and trends over time and recommend a refinement to the method using a robust variance estimator for testing overall effect. We conclude with a discussion of repurposing the method for Big Data meta-analysis and Genome Wide Association Studies for studying the importance of genetic variants in complex diseases. PMID:26343745

  16. Statistical properties of soil moisture images revisited

    NASA Astrophysics Data System (ADS)

    Oldak, Anna; Pachepsky, Yakov; Jackson, Thomas J.; Rawls, Walter J.

    2002-01-01

    Data from passive microwave remote sensing with an ESTAR L-band radiometer, deployed on an aircraft, were used to produce soil moisture images over the area of the Little Washita watershed in Oklahoma in 1992. This area was revisited during the Southern Great Plains 1997 Hydrology Experiment. This offered an opportunity to evaluate the time-specificity of the conclusions, relating to scaling of the surface soil moisture, that have been reported for 1992. The objective of this work was to compare scaling properties of soil moisture fields observed in 1992 and 1997. We analyzed one 1992 data set and three 1997 data sets, each covering several days of continuous drydown. Different resolutions were introduced by aggregating the pixels of original 200-m resolution into bigger square cells. Scaling in dependencies on resolution was observed for the variance of moisture content, for the within-cell variance, and for the first six moments about zero, the latter indicating multiscaling. Parameters of the scaling equations differed among four drying periods studied. However, once a scaling dependency on resolution was established in the beginning of a drying period, its shape was maintained during the drydown both in 1992 and 1997. Slopes of the dependencies changed only slightly, whereas the intercepts decreased as the drying progressed. Having constant slopes and intercepts dependent on average area water contents gives an opportunity to reduce the volume of observations needed to predict scaling of surface soil moisture during drydowns.

  17. Forensic seismology revisited

    NASA Astrophysics Data System (ADS)

    Douglas, A.

    2007-01-01

    The first technical discussions, held in 1958, on methods of verifying compliance with a treaty banning nuclear explosions, concluded that a monitoring system could be set up to detect and identify such explosions anywhere except underground: the difficulty with underground explosions was that there would be some earthquakes that could not be distinguished from an explosion. The development of adequate ways of discriminating between earthquakes and underground explosions proved to be difficult so that only in 1996 was a Comprehensive Nuclear Test Ban Treaty (CTBT) finally negotiated. Some of the important improvements in the detection and identification of underground tests—that is in forensic seismology—have been made by the UK through a research group at the Atomic Weapons Establishment (AWE). The paper describes some of the advances made in identification since 1958, particularly by the AWE Group, and the main features of the International Monitoring System (IMS), being set up to verify the Test Ban. Once the Treaty enters into force, then should a suspicious disturbance be detected the State under suspicion of testing will have to demonstrate that the disturbance was not a test. If this cannot be done satisfactorily the Treaty has provisions for on-site inspections (OSIs): for a suspicious seismic disturbance for example, an international team of inspectors will search the area around the estimated epicentre of the disturbance for evidence that a nuclear test really took place. Early observations made at epicentral distances out to 2,000 km from the Nevada Test Site showed that there is little to distinguish explosion seismograms from those of nearby earthquakes: for both source types the short-period (SP: ˜1 Hz) seismograms are complex showing multiple arrivals. At long range, say 3,000 10,000 km, loosely called teleseismic distances, the AWE Group noted that SP P waves—the most widely and well-recorded waves from underground explosions—were in contrast simple, comprising one or two cycles of large amplitude followed by a low-amplitude coda. Earthquake signals on the other hand were often complex with numerous arrivals of similar amplitude spread over 35 s or more. It therefore appeared that earthquakes could be recognised on complexity. Later however, complex explosion signals were observed which reduced the apparent effectiveness of complexity as a criterion for identifying earthquakes. Nevertheless, the AWE Group concluded that for many paths to teleseismic distances, Earth is transparent for P signals and this provides a window through which source differences will be most clearly seen. Much of the research by the Group has focused on understanding the influence of source type on P seismograms recorded at teleseismic distances. Consequently the paper concentrates on teleseismic methods of distinguishing between explosions and earthquakes. One of the most robust criteria for discriminating between earthquakes and explosions is the m b : M s criterion which compares the amplitudes of the SP P waves as measured by the body-wave magnitude m b, and the long-period (LP: ˜0.05 Hz) Rayleigh-wave amplitude as measured by the surface-wave magnitude M s; the P and Rayleigh waves being the main wave types used in forensic seismology. For a given M s, the m b for explosions is larger than for most earthquakes. The criterion is difficult to apply however, at low magnitude (say m b < 4.5) and there are exceptions—earthquakes that look like explosions. A difficulty with identification criteria developed in the early days of forensic seismology was that they were in the main empirical—it was not known why they appeared to work and if there were test sites or earthquakes where they would fail. Consequently the AWE Group in cooperation with the University of Cambridge used seismogram modelling to try and understand what controls complexity of SP P seismograms, and to put the m b : M s criterion on a theoretical basis. The results of this work show that the m b : M s criterion is robust because several factors con

  18. MetaVelvet: An Extension of Velvet Assembler to de novo Metagenome Assembly from Short Sequence Reads (Metagenomics Informatics Challenges Workshop: 10K Genomes at a Time)

    ScienceCinema

    Sakakibara, Yasumbumi [Keio University

    2013-01-22

    Keio University's Yasumbumi Sakakibara on "MetaVelvet: An Extension of Velvet Assembler to de novo Metagenome Assembly from Short Sequence Reads" at the Metagenomics Informatics Challenges Workshop held at the DOE JGI on October 12-13, 2011.

  19. Secret Public Key Protocols Revisited

    NASA Astrophysics Data System (ADS)

    Lim, Hoon Wei; Paterson, Kenneth G.

    Password-based protocols are important and popular means of providing human-to-machine authentication. The concept of secret public keys was proposed more than a decade ago as a means of securing password-based authentication protocols against off-line password guessing attacks, but was later found vulnerable to various attacks. In this paper, we revisit the concept and introduce the notion of identity-based secret public keys. Our new identity-based approach allows secret public keys to be constructed in a very natural way using arbitrary random strings, eliminating the structure found in, for example, RSA or ElGamal keys. We examine identity-based secret public key protocols and give informal security analyses, indicating that they are secure against off-line password guessing and other attacks.

  20. Revisiting the cosmological coherent oscillation

    NASA Astrophysics Data System (ADS)

    Kawasaki, Masahiro; Kitajima, Naoya; Nakayama, Kazunori

    2013-01-01

    It is often the case that scalar fields are produced in the early Universe in the form of coherent oscillation. These scalar fields may have huge abundances and affect the evolution of the Universe. In particular, if the lifetime is long enough, they may cause cosmological disasters. We revisit the issue of coherent oscillation of the scalar field when it couples with another oscillating scalar field, and find a situation that the abundance, or the amplitude of the oscillation, is significantly reduced by a variant type of the adiabatic suppression mechanism. As a concrete example, it is applied to the saxion, a flat direction in the supersymmetric axion model, and we show that the cosmological saxion problem is solved in a particular setup.

  1. Substorm Current Wedge Revisited

    NASA Technical Reports Server (NTRS)

    Kepko, L.; Mcpherron, R. L.; Amm, O.; Apatenkov, S.; Baumjohann, W.; Birn, J.; Lester, M.; Nakamura, R.; Pulkkinen, T. I.; Sergeev, V.

    2014-01-01

    Almost 40 years ago the concept of the substorm current wedge was developed to explain the magnetic signatures observed on the ground and in geosynchronous orbit during substorm expansion. In the ensuing decades new observations, including radar and low altitude spacecraft, MHD simulations, and theoretical considerations have tremendously advanced our understanding of this system. The AMPTE/IRM, THEMIS and Cluster missions have added considerable observational knowledge, especially on the important role of fast flows in producing the stresses that generate the substorm current wedge. Recent detailed, multi-spacecraft, multi-instrument observations both in the magnetosphere and in the ionosphere have brought a wealth of new information about the details of the temporal evolution and structure of the current system. While the large-scale picture remains valid, the new details call for revision and an update of the original view. In this paper we briefly review the historical development of the substorm current wedge, review recent in situ and ground based observations and theoretical work, and discuss the current active research areas. We conclude with a revised, time-dependent picture of the substorm current wedge that follows its evolution from the initial substorm flows through substorm expansion and recovery.

  2. Open Mushrooms: Stickiness revisited

    E-print Network

    Dettmann, Carl P

    2010-01-01

    We investigate mushroom billiards, a class of dynamical systems with sharply divided phase space. For typical values of the control parameter of the system $\\rho$, an infinite number of marginally unstable periodic orbits (MUPOs) exist making the system sticky in the sense that unstable orbits approach regular regions in phase space and thus exhibit regular behaviour for long periods of time. The problem of finding these MUPOs is expressed as the well known problem of finding optimal rational approximations of a real number, subject to some system-specific constraints. By introducing a generalized mushroom and using properties of continued fractions, we describe a zero measure set of control parameter values $\\rho\\in(0,1)$ for which all MUPOs are destroyed and therefore the system is less sticky. The open mushroom (billiard with a hole) is then considered in order to quantify the stickiness exhibited and exact leading order expressions for the algebraic decay of the survival probability function $P(t)$ are ca...

  3. Open Mushrooms: Stickiness revisited

    E-print Network

    Carl P. Dettmann; Orestis Georgiou

    2010-11-12

    We investigate mushroom billiards, a class of dynamical systems with sharply divided phase space. For typical values of the control parameter of the system $\\rho$, an infinite number of marginally unstable periodic orbits (MUPOs) exist making the system sticky in the sense that unstable orbits approach regular regions in phase space and thus exhibit regular behaviour for long periods of time. The problem of finding these MUPOs is expressed as the well known problem of finding optimal rational approximations of a real number, subject to some system-specific constraints. By introducing a generalized mushroom and using properties of continued fractions, we describe a zero measure set of control parameter values $\\rho\\in(0,1)$ for which all MUPOs are destroyed and therefore the system is less sticky. The open mushroom (billiard with a hole) is then considered in order to quantify the stickiness exhibited and exact leading order expressions for the algebraic decay of the survival probability function $P(t)$ are calculated for mushrooms with triangular and rectangular stems.

  4. Substorm Current Wedge Revisited

    NASA Astrophysics Data System (ADS)

    Kepko, L.; McPherron, R. L.; Amm, O.; Apatenkov, S.; Baumjohann, W.; Birn, J.; Lester, M.; Nakamura, R.; Pulkkinen, T. I.; Sergeev, V.

    2015-07-01

    Almost 40 years ago the concept of the substorm current wedge was developed to explain the magnetic signatures observed on the ground and in geosynchronous orbit during substorm expansion. In the ensuing decades new observations, including radar and low-altitude spacecraft, MHD simulations, and theoretical considerations have tremendously advanced our understanding of this system. The AMPTE/IRM, THEMIS and Cluster missions have added considerable observational knowledge, especially on the important role of fast flows in producing the stresses that generate the substorm current wedge. Recent detailed, multi-spacecraft, multi-instrument observations both in the magnetosphere and in the ionosphere have brought a wealth of new information about the details of the temporal evolution and structure of the current system. While the large-scale picture remains valid, the new details call for revision and an update of the original view. In this paper we briefly review the historical development of the substorm current wedge, review recent in situ and ground-based observations and theoretical work, and discuss the current active research areas. We conclude with a revised, time-dependent picture of the substorm current wedge that follows its evolution from the initial substorm flows through substorm expansion and recovery.

  5. Seismic attributes revisited

    SciTech Connect

    Taner, M.T.; O`Doherty, R.; Schuelke, J.S.; Baysal, E.

    1994-12-31

    Since their introduction in early 1970`s seismic attributes have become one of the most commonly used and powerful interpretation tools. In earlier applications they were considered as a management display tool. This view has changed rapidly as their use in interpretation expanded. Results were analyzed in a qualitative manner. Recently, as evidenced from increasing number of papers, attribute use finally became more quantitative through calibration with well bore measurements. In this paper the authors will present a review of basic attributes, their recently introduced derivatives and their expected significance. They will also classify them with respect to their computation and their end use. They define all seismically driven parameters as the Seismic Attributes. They can be velocity, amplitude, rate of change of any of them with respect to time or space and so on. They can be computed from pre-stack or post stack data sets. Some of the attributes computed from complex traces such as envelope, phase and etc. correspond to the various measurements of the propagating wave-front. They will call those the physical Attributes. These attributes may be used for prediction or extrapolation of lithological or reservoir characteristics. Others are computed from the reflection configurations and continuity. They will call these Geometric Attributes. These are used in structural and stratigraphic interpretation. In this paper they will confine themselves to the classification and definition of the attributes and their possible uses. They will give examples from different geological settings.

  6. Membrane Duality Revisited

    E-print Network

    Duff, M J; Percacci, R; Pope, C N; Samtleben, H; Sezgin, E

    2015-01-01

    Just as string T-duality originates from transforming field equations into Bianchi identities on the string worldsheet, so it has been suggested that M-theory U-dualities originate from transforming field equations into Bianchi identities on the membrane worldvolume. However, this encounters a problem unless the target space has dimension $D = p + 1$. We identify the problem to be the nonintegrability of the U-duality transformation assigned to the pull-back map. Just as a double geometry renders manifest the $O(D,D)$ string T-duality, here we show in the case of the M2-brane in $D = 3$ that a generalised geometry renders manifest the $SL(3) \\times SL(2)$ U-duality. In the case of M2-brane in $D=4$, with and without extra target space coordinates, we show that only the ${\\rm GL}(4,R)\\ltimes R^4$ subgroup of the expected $SL(5,R)$ U-duality symmetry is realised.

  7. A Vanishing Star Revisited

    NASA Astrophysics Data System (ADS)

    1999-07-01

    VLT Observations of an Unusual Stellar System Reinhold Häfner of the Munich University Observatory (Germany) is a happy astronomer. In 1988, when he was working at a telescope at the ESO La Silla observatory, he came across a strange star that suddenly vanished off the computer screen. He had to wait for more than a decade to get the full explanation of this unusual event. On June 10-11, 1999, he observed the same star with the first VLT 8.2-m Unit Telescope (ANTU) and the FORS1 astronomical instrument at Paranal [1]. With the vast power of this new research facility, he was now able to determine the physical properties of a very strange stellar system in which two planet-size stars orbit each other. One is an exceedingly hot white dwarf star , weighing half as much as the Sun, but only twice as big as the Earth. The other is a much cooler and less massive red dwarf star , one-and-a-half times the size of planet Jupiter. Once every three hours, the hot star disappears behind the other, as seen from the Earth. For a few minutes, the brightness of the system drops by a factor of more than 250 and it "vanishes" from view in telescopes smaller than the VLT. A variable star named NN Serpentis ESO PR Photo 30a/99 ESO PR Photo 30a/99 [Preview - JPEG: 400 x 468 pix - 152k] [Normal - JPEG: 800 x 936 pix - 576k] [High-Res - JPEG: 2304 x 2695 pix - 4.4M] Caption to ESO PR Photo 30a/99 : The sky field around the 17-mag variable stellar system NN Serpentis , as seen in a 5 sec exposure through a V(isual) filter with VLT ANTU and FORS1. It was obtained just before the observation of an eclipse of this unsual object and served to centre the telescope on the corresponding sky position. The field shown here measures 4.5 x 4.5 armin 2 (1365 x 1365 pix 2 ; 0.20 arcsec/pix). The field is somewhat larger than that shown in Photo 30b/99 and has the same orientation to allow comparison: North is about 20° anticlockwise from the top and East is 90° clockwise from that direction. The unsual star in question is designated NN Serpentis , or just NN Ser . As the name indicates, it is located in the constellation of Serpens (The Serpent), about 12° north of the celestial equator. A double letter, here "NN", is used to denote variable stars [2]. It is a rather faint object of magnitude 17, about 25,000 times fainter than what can be perceived with the unaided eye. The distance is about 600 light-years (180 pc). In July 1988, Reinhold Häfner performed observations of NN Ser (at that time still known by its earlier name PG 1550+131 ) with the Danish 1.54-m telescope at La Silla. He was surprised, but also very pleased to discover that it underwent a very deep eclipse every 187 minutes. Within less than 2 minutes, the brightness dropped by a factor of more than 100 (5 magnitudes). During the next 9 minutes, the star completely disappeared from view - it was too faint to be observed with this telescope. It then again reappeared and the entire event was over after just 11 minutes. Why eclipses are so important for stellar studies An eclipse occurs when one of the stars in a binary stellar system moves in front of the other, as seen by the observer. The effect is similar to what happens during a solar eclipse when the Moon moves in front of the Sun. In both cases, the eclipse may be partial or total , depending on whether or not the eclipsed star (or the Sun) is completely hidden from view. The occurence of eclipses in stellar systems, as seen from the Earth, depends on the spatial orientation of the orbital plane and the sizes of the two stars. Two eclipses take place during one orbital revolution, but they may not both be observable. The physical properties of the two stars in a binary system (e.g., the sizes of the stars, the size and shape of the orbit, the distribution of the light on the surfaces of the stars, their temperatures etc.) can be determined from the measured "light-curve" of the system (a plot of brightness vrs. time). The stars are always too close to each other to be seen as anything but a point of lig

  8. Hotspot swells revisited

    NASA Astrophysics Data System (ADS)

    King, Scott D.; Adam, Claudia

    2014-10-01

    The first attempts to quantify the width and height of hotspot swells were made more than 30 years ago. Since that time, topography, ocean-floor age, and sediment thickness datasets have improved considerably. Swell heights and widths have been used to estimate the heat flow from the core-mantle boundary, constrain numerical models of plumes, and as an indicator of the origin of hotspots. In this paper, we repeat the analysis of swell geometry and buoyancy flux for 54 hotspots, including the 37 considered by Sleep (1990) and the 49 considered by Courtillot et al. (2003), using the latest and most accurate data. We are able to calculate swell geometry for a number of hotspots that Sleep was only able to estimate by comparison with other swells. We find that in spite of the increased resolution in global bathymetry models there is significant uncertainty in our calculation of buoyancy fluxes due to differences in our measurement of the swells’ width and height, the integration method (volume integration or cross-sectional area), and the variations of the plate velocities between HS2-Nuvel1a (Gripp and Gordon, 1990) and HS3-Nuvel1a (Gripp and Gordon, 2002). We also note that the buoyancy flux for Pacific hotspots is in general larger than for Eurasian, North American, African and Antarctic hotspots. Considering that buoyancy flux is linearly related to plate velocity, we speculate that either the calculation of buoyancy flux using plate velocity over-estimates the actual vertical flow of material from the deep mantle or that convection in the Pacific hemisphere is more vigorous than the Atlantic hemisphere.

  9. The Armstrong experiment revisited

    NASA Astrophysics Data System (ADS)

    Fuchs, Elmar C.; Wexler, Adam D.; Paulitsch-Fuchs, Astrid H.; Agostinho, Luewton L. F.; Yntema, Doekle; Woisetschläger, Jakob

    2014-04-01

    When a high-voltage direct-current is applied to two beakers filled with water or polar liquid dielectrica, a horizontal bridge forms between the two beakers. This experiment was first carried out by Lord Armstrong in 1893 and then forgotten until recently. Such bridges are stable by the action of electrohydrodynamic (EHD) forces caused by electric field gradients counteracting gravity. Due to these gradients a permanent pumping of liquid from one beaker into the other is observed. At macroscopic scale several of the properties of a horizontal water bridge can be explained by modern electrohydrodynamics, analyzing the motion of fluids in electric fields. Whereas on the molecular scale water can be described by quantum mechanics, there is a conceptual gap at mesoscopic scale which is bridged by a number of theories including quantum mechanical entanglement and coherent structures in water - theories that we discuss here. Much of the phenomenon is already understood, but even more can still be learned from it, since such "floating" liquid bridges resemble a small high voltage laboratory of their own: The physics of liquids in electric fields of some kV/cm can be studied, even long time experiments like neutron or light scattering are feasible since the bridge is in a steady-state equilibrium and can be kept stable for hours. It is also an electro-chemical reactor where compounds are transported through by the EHD flow, enabling the study of electrochemical reactions under potentials which are otherwise not easily accessible. Last but not least the bridge provides the experimental biologist with the opportunity to expose living organisms such as bacteria to electric fields without killing them, but with a significant influence on their behavior, and possibly, even on their genome.

  10. The Ammonia Dimer Revisited

    NASA Astrophysics Data System (ADS)

    Dawes, Richard; Van Der Avoird, Ad

    2012-06-01

    The conclusion from microwave spectra by Nelson, Fraser, and Klemperer that the ammonia dimer has a nearly cyclic structure led to much debate about the issue of whether (NH_3)_2 is hydrogen bonded. This structure was surprising because most {ab initio} calculations led to a classical, nearly linear, hydrogen-bonded structure. An obvious explanation of the discrepancy between the outcome of these calculations and the microwave data which led Nelson {et al.} to their ``surprising structure'' might be the effect of vibrational averaging: the electronic structure calculations focus on finding the minimum of the intermolecular potential, the experiment gives a vibrationally averaged structure. Isotope substitution studies seemed to indicate, however, that the complex is nearly rigid. Additional data became available from high-resolution molecular beam far-infrared spectroscopy in the Saykally group. These spectra, displaying large tunneling splittings, indicate that the complex is very floppy. The seemingly contradictory experimental data were explained when it became possible to calculate the vibration-rotation-tunneling (VRT) states of the complex on a six-dimensional intermolecular potential surface. The potential used was a simple model potential, with parameters fitted to the far-infrared data. Now, for the first time, a six-dimensional potential was computed by high level {ab initio} methods and this potential will be used in calculations of the VRT states of (NH_3)_2 and (ND_3)_2. So, we will finally be able to answer the question whether the conclusions from the model calculations are indeed a valid explanation of the experimental data. D. Nelson, G. T. Fraser, and W. Klemperer J. Chem. Phys. 83 6201 (1985) J. G. Loeser, C. A. Schmuttenmaer, R. C. Cohen, M. J. Elrod, D. W. Steyert, R. J. Saykally, R. E. Bumgarner, and G. A. Blake J. Chem. Phys. 97 4727 (1992) E. H. T. Olthof, A. van der Avoird, and P. E. S. Wormer J. Chem. Phys. 101 8430 (1994) E. H. T. Olthof, A. van der Avoird, P. E. S. Wormer, J. G. Loeser, and R. J. Saykally J. Chem. Phys. 101 8443 (1994)

  11. Fire and Ice Revisited

    NASA Astrophysics Data System (ADS)

    Macdonald, F. A.; Rooney, A.; Dudas, F. O.; Schmitz, M. D.

    2011-12-01

    Recent U-Pb ID-TIMS ages from NW Canada demonstrate a rough coincidence between the Franklin LIP and the initiation of the Sturtian glaciation(s). These events could be mechanistically related through an increase in weatherability of the continents and/or from an increase in planetary albedo. Both of these scenarios have predictions for the relative timing of the emplacement of the Franklin LIP and the onset of glaciations and for the Sr and Os composition of seawater. We report new Re/Os and U-Pb ID-TIMS zircon ages and Sr, Os, and C isotope results from Mongolia and northwest Canada. These data suggest: 1) The Islay carbon isotope anomaly in NW Canada is separated from the onset of the Sturtian glaciation(s) by >10 Myrs and is thus not directly related to the initiation of glaciations. 2) The Os isotopic composition of pre-Rapitan (Sturtian) sediments in NW Canada is remarkably unradiogenic, consistent with intense basalt weathering; however, it is uncertain if these strata were in full communication with the global ocean. 3) The Sr isotopic composition of pre-Strutian sediments on multiple continents also show a decrease leading into the glaciations, again consistent with an increase in basalt weathering prior to the glaciations. 4) The Os isotope composition of the post-glacial Twitya Formation in NW Canada is much more radiogenic than pre-glacial strata and likely reflects intense weathering of the continental crust associated with the deglaciation. 5) The Sr isotopic composition of seawater increases rapidly after both the Sturtian and Marinoan glaciations and is otherwise relatively stable in the Cryogenian, testifying to the extreme effect of the glaciations on the Sr isotopic composition of seawater. 6) The only other inflection in our new high-resolution Cryogenian Sr isotope curve occurs across the Tayshir carbon isotope anomaly, confirming links between the carbon cycle and continental weathering. 7) Current age constraints suggest a long duration of the Sturtian glaciation(s), >10 Myr. Together, these data give legs to the 'Fire and Ice' hypothesis of Godderis et al., 2003, and indicate major changes in weathering proxies on million-year timescales both before and after the Sturtian glaciations(s). However, it remains possible that the increased weatherability merely set the stage for global glaciations, leaving the Earth more vulnerable to a sudden change in insolation. Further precise ages and modeling will shed additional light on the initiation mechanism of Snowball Earth.

  12. Conformal Lorentz geometry revisited

    NASA Astrophysics Data System (ADS)

    Teleman, Kostake

    1996-02-01

    The group U(2,2) and its subgroup SU(2,2) were considered by Penrose in his study of the conformal compactification M of the Minkowski space M [R. Penrose and W. Rindler, Spinors and Space-Time (Cambridge University, Cambridge, 1986) and R. O. Wells, Jr., Bull. Am. Math. Soc. I, 2 (1979)]. The standard representation of SU(2,2) in C4 and in M are the corner stones of twistor theory, which was created by Penrose to the double purpose of obtaining new solutions of Einstein equations and new insights on gravitational radiation. We think that other representations of SU(2,2) or U(2,2) could also bring some information in relativity [see also, Barut O. Asjim, in Noncompact Lie Groups and some of their Applications, edited by E. A. Tanner and R. Wilson (Kluwer Academic, Dordrecht, 1994), p. 103] and, accordingly, we propose an extension of Penrose twistor program. In this paper we deal with a new U(2,2)-space, which we denote by W. We show first that the SU(2,2)-space M introduced by Penrose is isomorphic to U(2), endowed with an action of SU(2,2) given by non-Abelian homographic transformations. These transformations keep invariant the equation det(u-v)=0, characterizing the pairs (u,v)?U(2)×U(2) such that ``u lies on the light-cone of v.'' By definition, our space W consists of all pairs (u,v)?U(2)×U(2) satisfying the condition det(u-v)?0. The starting point of this article is the observation that W carries an SU(2,2)-invariant pseudo-Riemannian metric L:=Tr[(u-v)-1u? ×(u-v)-1v?], of signature (4,4). (W,L) is in fact an irreducible symmetric space in Cartan's sense, which is isomorphic to the quotient SO(2,4)/S[O(1,1)×O(1,3)]. As an irreducible symmetric space, it is an 8-dimensional Einstein space, whose Ricci tensor is proportional to the metric tensor. We study the geodesic paths of this space giving the general solutions in terms of initial data and studying the constants of motion. In particular we determine the geodesic paths which exhibit two periods. We also show that Mach's principle on inertial motions receives an explanation in our theory by considering the particular geodesic paths, for which one of the partners of an interacting pair is fixed and sent to infinity. In fact we study a dynamical system (W,L) which presents some formal and topological similarities with a system of two particles interacting gravitationally. (W,L) is the only conformally invariant relativistic two-point dynamical system. At the end we show that W can be naturally regarded as the base of a principal GL(2,C)-bundle which comes with a natural connection. We study this bundle from differential geometric point of view. Physical interpretations will be discussed in a future paper. This text is an improvement of a previous version, which was submitted under the title ``Hypertwistor Geometry.'' [See, K. Teleman, ``Hypertwistor Geometry (abstract),'' 14th International Conference on General Relativity and Gravitation, Florence, Italy, 1995.] The change of the title and many other improvements are due to the valuable comments of the referee, who also suggested the author to avoid hazardous interpretations.

  13. Time

    ERIC Educational Resources Information Center

    Circle, David

    2005-01-01

    When a teacher gives their time to a student, it is more significant to that student than anything else one could do for him or her. Music teachers deal with time all the time. Someone once said that "time is like money: we never have enough." This may seem true; however, time is not like money. One can make more money, but one cannot "make time."…

  14. Screening Li-Ion Batteries for Internal Shorts

    NASA Technical Reports Server (NTRS)

    Darcy, Eric

    2006-01-01

    The extremely high cost of aerospace battery failures due to internal shorts makes it essential that their occurrence be very rare, if not eliminated altogether. With Li-ion cells/batteries, the potentially catastrophic safety hazard that some internal shorts present adds additional incentive for prevention. Prevention can be achieved by design, manufacturing measures, and testing. Specifically for NASA s spacesuit application, a Li-ion polymer pouch cell battery design is in its final stages of production. One of the 20 flight batteries fabricated and tested developed a cell internal short, which did not present a safety hazard, but has required revisiting the entire manufacturing and testing process. Herein are the details of the failure investigation that followed to get to root cause of the internal short and the corrective actions that will be taken. The resulting lessons learned are applicable to most Li-ion battery applications.

  15. Double Photoionization of Lithium Revisited

    NASA Astrophysics Data System (ADS)

    Wehlitz, Ralf; Luki?, Dragan

    2009-05-01

    In a previous paperootnotetextR. Wehlitz, J.B. Bluett , and S.B. Whitfield, Phys. Rev. Lett. 89, 093002 (2002) we believed to have seen oscillations in the double-photoionization cross section of lithium. However, a recent investigation revealed that resonances at twice the photon energy (compared to the near-threshold energy region) are more pronounced than had been expectedootnotetextR. Wehlitz and P.N. Jurani'c, Phys. Rev. A 74, 042721 (2006). This prompted us to revisit the near-threshold region of the lithium double-to-single photoionization ratio. Using a slightly higher energy resolution in a new experiment on the same beamline, we could identify resonances in that ratio due to second-order light. While the second-order light contribution is small, so is the double-photoionization cross section in first-order light near threshold. The ``resonances'' observed near threshold match the inner-shell resonances at twice the photon energy fairly well and can indeed explain the previously seen ``oscillations''.

  16. Time scales of turbulent relative dispersion

    NASA Astrophysics Data System (ADS)

    Bitane, Rehab; Homann, Holger; Bec, Jérémie

    2012-10-01

    Tracers in a turbulent flow separate according to the celebrated t3/2 Richardson-Obukhov law, which is usually explained by a scale-dependent effective diffusivity. Here, supported by state-of-the-art numerics, we revisit this argument. The Lagrangian correlation time of velocity differences increases too quickly for validating this approach, but acceleration differences decorrelate on dissipative time scales. Phenomenological arguments are used to relate the behavior of separations to that of a “local energy dissipation,” defined as the average ratio between the cube of the longitudinal velocity difference and the distance between the two tracers. This quantity is shown to stabilize on short time scales and this results in an asymptotic diffusion ?t1/2 of velocity differences. The time of convergence to this regime is shown to be that of deviations from Batchelor's initial ballistic regime, given by a scale-dependent energy dissipation time rather than the usual turnover time. It is finally demonstrated that the fluid flow intermittency should not affect this long-time behavior of the relative motion.

  17. The shape of the Venusian bow shock at solar minimum and maximum: Revisit based on VEX observations

    NASA Astrophysics Data System (ADS)

    Shan, Lican; Lu, Quanming; Mazelle, Christian; Huang, Can; Zhang, Tielong; Wu, Mingyu; Gao, Xinliang; Wang, Shui

    2015-05-01

    Several factors control the bow shock position at Venus, including short-term period responses (solar wind dynamic pressure) and long-term period variations (solar activity). Based on Venus Express (VEX) observations, we revisit the influence of solar activity on the Venusian bow shock location, by accurately determining not only the shock terminator distance but also the subsolar point with a three-parameter fit (TPF) method. At the same time, VEX covers a larger range of solar zenith angles (SZA) at the Venusian bow shock (from about 10 to 135 degrees) than the Pioneer Venus Orbiter (PVO) spacecraft. Fitting results display that the Venusian bow shock is farther away from Venus at solar maximum than at solar minimum. The subsolar stand-off distance increases from 1.364 planetary radii at solar minimum to 1.459RV at solar maximum, while the terminator shock distance changes from 2.087RV to 2.146RV. Inspection of the bow shock and the induced magnetosphere boundary (IMB) locations clearly shows a positive correlation for every orbit, while the average bow shock location is not responsive to changes in the solar wind dynamic pressure.

  18. Secrets of Nature: The Bacon Debates Revisited

    E-print Network

    Merchant, Carolyn

    Secrets of Nature: The Bacon Debates Revisited Carolyn Merchant Francis Bacon rose to power during, ``Francis Bacon, Feminist Historiography, and the Dominion of Nature,'' JHI, 69 (2008): 117­41. Vickers, controlled experimental method developed by Francis Bacon and his followers. Copyright by Journal

  19. Modeling skin permeation revisited Gabriel Wittum

    E-print Network

    Hackbusch, Wolfgang

    Modeling skin permeation revisited Gabriel Wittum Computing diffusion through human skin is usually diffusion through human skin using two and three dimensional models. First computations for this problem were made a decade ago, yielding new insight into permeation pathways through human skin, which were

  20. The Rotating Morse-Pekeris Oscillator Revisited

    ERIC Educational Resources Information Center

    Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

    2008-01-01

    The Morse-Pekeris oscillator model for the calculation of the vibration-rotation energy levels of diatomic molecules is revisited. This model is based on the realization of a second-order exponential expansion of the centrifugal term about the minimum of the vibrational Morse oscillator and the subsequent analytical resolution of the resulting…

  1. Phenomenology of n -n ¯ oscillations revisited

    NASA Astrophysics Data System (ADS)

    Gardner, S.; Jafari, E.

    2015-05-01

    We revisit the phenomenology of n -n ¯ oscillations in the presence of external magnetic fields, highlighting the role of spin. We show, contrary to long-held belief, that the n -n ¯ transition rate need not be suppressed, opening new opportunities for its empirical study.

  2. Biodiversity measures revisited Natalia Petrovskaya a

    E-print Network

    Petrovskaya, Natalia B.

    Biodiversity measures revisited Natalia Petrovskaya a , Sergei Petrovskii b,c,*, Bai-Lian Li c, Riverside, CA 92521-0124, USA 1. Introduction Loss of biodiversity in various ecosystems all over the world to recognize the main threats for communities functioning and reasons for biodiversity loss; examples

  3. The Evil of Banality: Arendt Revisited

    ERIC Educational Resources Information Center

    Minnich, Elizabeth

    2014-01-01

    "The banality of evil" (Arendt) remains controversial and useful. Ironically, the concept is now itself a banality. To revisit and extend it, we consider the "evil of banality", the profound dangers of cliched thoughtlessness. A distinction is proposed: "intensive" versus "extensive evils". The former takes…

  4. Phenomenology of n - n ¯ oscillations revisited

    DOE PAGESBeta

    Gardner, S.; Jafari, E.

    2015-05-22

    We revisit the phenomenology of n-n¯ oscillations in the presence of external magnetic fields, highlighting the role of spin. We show, contrary to long-held belief, that the n-n¯ transition rate need not be suppressed, opening new opportunities for its empirical study.

  5. Bohr’s ‘Light and Life’ revisited

    NASA Astrophysics Data System (ADS)

    Nussenzveig, H. M.

    2015-11-01

    I revisit Niels Bohr’s famous 1932 ‘Light and Life’ lecture, confronting it with current knowledge. Topics covered include: life origin and evolution, quantum mechanics and life, brain and mind, consciousness and free will, and light as a tool for biology, with special emphasis on optical tweezers and their contributions to biophysics. Specialized knowledge of biology is not assumed.

  6. Rational Secret Sharing, Revisited S. Dov Gordon

    E-print Network

    International Association for Cryptologic Research (IACR)

    Rational Secret Sharing, Revisited S. Dov Gordon Jonathan Katz July 11, 2006 Abstract We consider the problem of secret sharing among n rational players. This problem was introduced by Halpern and Teague. Contrary to their claim, we show a protocol for rational secret sharing among n = 2 players; our protocol

  7. The Random Oracle Methodology, Revisited Ran Canetti

    E-print Network

    Goldreich, Oded

    The Random Oracle Methodology, Revisited Ran Canetti y Oded Goldreich z Shai Halevi x February 15 in the Random Oracle Model, and the security of the schemes that result from implementing the random oracle: There exist signature and encryption schemes that are secure in the Random Oracle Model, but for which any

  8. The Random Oracle Methodology, Revisited (preliminary version)

    E-print Network

    Goldreich, Oded

    The Random Oracle Methodology, Revisited (preliminary version) Ran Canetti Oded Goldreich y Shai of cryptographic schemes in the Random Oracle Model, and the security of the schemes which result from implementing the random oracle by so called \\cryptographic hash functions". The mainresult of this paper is a negative one

  9. The Random Oracle Methodology, Revisited (preliminary version)

    E-print Network

    Goldreich, Oded

    The Random Oracle Methodology, Revisited (preliminary version) Ran Canetti \\Lambda Oded Goldreich y of cryptographic schemes in the Random Oracle Model, and the security of the schemes which result from implementing the random oracle by so called ``cryptographic hash functions''. The main result of this paper is a negative

  10. Ant Foraging Revisited Liviu Alexandru Panait1

    E-print Network

    Luke, Sean

    Ant Foraging Revisited Liviu Alexandru Panait1 and Sean Luke1 1. Department of Computer Science: lpanait@cs.gmu.edu Abstract Previous artificial (non-biological) ant foraging models have to date relied ants with the knowledge of the nest direction. In contrast, the work presented solves ant foraging

  11. Empirically Revisiting the Test Independence Assumption

    E-print Network

    Ernst, Michael

    Empirically Revisiting the Test Independence Assumption Sai Zhang, Darioush Jalali, Jochen Wuttke}@cs.washington.edu ABSTRACT In a test suite, all the test cases should be independent: no test should affect any other test's result, and running the tests in any order should produce the same test results. Techniques such as test

  12. ORIGINAL ARTICLE Cytosolic potassium homeostasis revisited: 42

    E-print Network

    Kronzucker, Herbert J.

    ORIGINAL ARTICLE Cytosolic potassium homeostasis revisited: 42 K-tracer analysis in Hordeum vulgare of the flexibility, rather than strict homeostasis, of cellular K+ maintenance, and of the dynamic interaction analysis Æ 42 K Æ Hordeum Ion transport Æ Homeostasis Introduction Potassium (K+ ) availability in both

  13. Human Visual Perception and Kolmogorov Complexity: Revisited

    E-print Network

    Kreinovich, Vladik

    Human Visual Perception and Kolmogorov Complexity: Revisited Vladik Kreinovich and Luc Longpr distribution instead. With this lim- itation in mind, we conclude that we cannot store arbitrary probability a mathematical foundations for the above theoretical explanation of the randomized-memorization phenomena. Human

  14. Human Visual Perception and Kolmogorov Complexity: Revisited

    E-print Network

    Kreinovich, Vladik

    Human Visual Perception and Kolmogorov Complexity: Revisited Vladik Kreinovich and Luc Longpr store its probability distribution instead. With this lim­ itation in mind, we conclude that we cannot of the randomized­memorization phenomena. Human visual perception and complexity. If we see an image, how ac

  15. Mutual Exclusion Revisited Boleslaw K. Szymanski

    E-print Network

    Szymanski, Boleslaw K.

    Mutual Exclusion Revisited Boleslaw K. Szymanski Computer Science Department Rensselaer Polytechnic Institute Troy, NY 12180 Abstract A family of four mutual exclusion algorithms is pre- sented. Its members vary from a simple three-bit linear wait mutual exclusion to the four-bit first-come first- served

  16. Revisiting the Skills Agenda: A Complicated Geography

    ERIC Educational Resources Information Center

    Saunders, Angharad

    2011-01-01

    This paper revisits the skills agenda and suggests that in light of shifts from supply-side to demand-led provision within the UK higher education sector, there is a need to think more critically about the role and place of skills within university curricula. It suggests that if universities are to respond effectively to sector changes, then the…

  17. The LCA Problem Revisited Michael A. Bender

    E-print Network

    Danner, Andrew

    The LCA Problem Revisited Michael A. Bender SUNY Stony Brook Mart´in Farach-Colton ¡ Rutgers thus dispel the fre- quently held notion that an optimal LCA computation is unwieldy (LCA), Range Minimum Query (RMQ), Cartesian Tree. 1 Introduction One of the most fundamental

  18. The LCA Problem Revisited Michael A. Bender

    E-print Network

    Bender, Michael

    The LCA Problem Revisited Michael A. Bender£ SUNY Stony Brook Mart´in Farach-ColtonÝ Rutgers thus dispel the fre- quently held notion that an optimal LCA computation is unwieldy (LCA), Range Minimum Query (RMQ), Cartesian Tree. 1 Introduction One of the most fundamental

  19. The Do-Calculus Revisited Judea Pearl

    E-print Network

    California at Los Angeles, University of

    The Do-Calculus Revisited Judea Pearl Keynote Lecture, August 17, 2012 UAI-2012 Conference and Pearl, 2006] and the graphi- cal criteria of [Tian and Shpitser, 2010] have laid this identification areas: mediation analysis [Pearl, 2012], trans- portability [Pearl and Bareinboim, 2011] and meta

  20. Vesicle model with bending energy revisited

    E-print Network

    Henri Gouin

    2015-10-16

    The equations governing the conditions of mechanical equilibrium in fluid membranes subject to bending are revisited thanks to the principle of virtual work. The note proposes systematic tools to obtain the shape equation and the line condition instead of Christoffel symbols and the complex calculations they entail. The method seems adequate to investigate all problems involving surface energies.