WorldWideScience

Sample records for rates local densities

  1. Local space density and formation rate of planetary nebulae

    NARCIS (Netherlands)

    Pottasch, [No Value

    1996-01-01

    Individual distances of 50 nearby planetary nebulae are determined using a variety of methods, but excluding statistical methods or distance scales. These distances, together with a discussion of the sample completeness, are used to determine local PN formation rate. Together with the brightness of

  2. The Environments of Local Luminous Infrared Galaxies: Star Formation Rates increase with Density

    CERN Document Server

    Tekola, Abiy G; Berlind, Andreas

    2011-01-01

    This work studies the environments and star formation relationships of local luminous infrared galaxies (LIRG) in comparison to other types of local and distant z~1 galaxies. The infrared (IR) galaxies are drawn from the IRAS sample. The density of the environment is quantified using 6dF and Point Source Catalogue redshift survey (PSCz) galaxies in a cylinder of 2 Mpc radius and 10 Mpc length. Our most important result shows the existence of a dramatic density difference between local LIRGs and local non-LIRG IR galaxies. LIRGs live in denser environments than non-LIRG IR galaxies implying that L_IR = 10^11 L_sun marks an important transition point among IR-selected local galaxies. We also find that there is a strong correlation between the densities around LIRGs and their L_IR luminosity. On the other hand, the IR-activity of non-LIRG IR galaxies does not show any dependence on environment. Moreover, it is noted that the star formation rate and density around LIRGs are correlated. This trend in local LIRGs i...

  3. Voyager 1 in the Local Interstellar Medium: Cosmic-ray Energy Density and Ionization Rate

    Science.gov (United States)

    Cummings, A. C.; Stone, E. C.; Heikkila, B. C.; Lal, N.; Webber, W. R.; Johannesson, G.; Moskalenko, I.; Orlando, E.; Porter, T.

    2015-12-01

    We present the energy spectra of cosmic ay nuclei and electrons in the local interstellar medium (LISM) from the Cosmic Ray Subsystem on Voyager 1 (V1). We use four models of the local interstellar spectra of nuclei and one of electrons that are constrained by the observations to compute the energy density and ionization rate of atomic H in the LISM above 3 MeV for electrons and protons and above 3 MeV/nuc for nuclei with Z > 1. We find that the total cosmic-ray energy density is in the range 0.82-0.97 eV/cm3, which includes a contribution of 0.023 eV/cm3 from electrons. We find the cosmic-ray ionization rate of atomic H to be in the range 1.45-1.58 x 10-17 s-1, which is a factor of more than 10 below the cosmic-ray ionization rate in diffuse interstellar clouds based on astrochemistry methods. We discuss possible reasons for this difference. Voyager data analysis is supported by NASA Grant NNN12AA012. GALPROP development is supported by NASA Grants NNX13AC47G and NNX10AE78G.

  4. The local mass density

    Science.gov (United States)

    Veeder, G. J.

    1974-01-01

    An improved mass-luminosity relation for faint main-sequence stars derived from recently revised masses for some faint double stars is presented. The total local mass density is increased to nearly 0.2 solar masses per cu pc. This estimate is as large as the mass density required by Oort's (1965) dynamical analysis of stellar motions perpendicular to the galactic plane if the mass is concentrated in a narrow layer.

  5. The ALFALFA Hα Survey. I. Project Description and The Local Star-formation Rate Density from the Fall Sample

    Science.gov (United States)

    Van Sistine, Angela; Salzer, John J.; Sugden, Arthur; Giovanelli, Riccardo; Haynes, Martha P.; Janowiecki, Steven; Jaskot, Anne E.; Wilcots, Eric M.

    2016-06-01

    The ALFALFA Hα survey utilizes a large sample of H i-selected galaxies from the ALFALFA survey to study star formation (SF) in the local universe. ALFALFA Hα contains 1555 galaxies with distances between ˜20 and ˜100 Mpc. We have obtained continuum-subtracted narrowband Hα images and broadband R images for each galaxy, creating one of the largest homogeneous sets of Hα images ever assembled. Our procedures were designed to minimize the uncertainties related to the calculation of the local SF rate density (SFRD). The galaxy sample we constructed is as close to volume-limited as possible, is a robust statistical sample, and spans a wide range of galaxy environments. In this paper, we discuss the properties of our Fall sample of 565 galaxies, our procedure for deriving individual galaxy SF rates, and our method for calculating the local SFRD. We present a preliminary value of log(SFRD[M ⊙ yr-1 Mpc-3]) = -1.747 ± 0.018 (random) ±0.05 (systematic) based on the 565 galaxies in our Fall sub-sample. Compared to the weighted average of SFRD values around z ≈ 2, our local value indicates a drop in the global SFRD of a factor of 10.2 over that lookback time.

  6. Foerster resonance energy transfer rate and local density of optical states are uncorrelated in any dielectric nanophotonic medium

    CERN Document Server

    Wubs, Martijn

    2015-01-01

    Motivated by the ongoing debate about nanophotonic control of Foerster resonance energy transfer (FRET), notably by the local density of optical states (LDOS), we study an analytic model system wherein a pair of ideal dipole emitters - donor and acceptor - exhibit energy transfer in the vicinity of an ideal mirror. The FRET rate is controlled by the mirror up to distances comparable to the donor-acceptor distance, that is, the few-nanometer range. For vanishing distance, we find a complete inhibition or a four-fold enhancement, depending on dipole orientation. For mirror distances on the wavelength scale, where the well-known `Drexhage' modification of the spontaneous-emission rate occurs, the FRET rate is constant. Hence there is no correlation between the Foerster (or total) energy transfer rate and the LDOS. At any distance to the mirror, the total energy transfer between a closely-spaced donor and acceptor is dominated by Foerster transfer, i.e., by the static dipole-dipole interaction that yields the cha...

  7. THE EFFECTS OF POPULATION-SIZE AND PLANT-DENSITY ON OUTCROSSING RATES IN LOCALLY ENDANGERED SALVIA-PRATENSIS

    NARCIS (Netherlands)

    VANTREUREN, R; BIJLSMA, R; OUBORG, NJ; VANDELDEN, W

    Multilocus outcrossing rates were estimated in natural and experimental populations of Salvia pratensis, an entomophilous, gynodioecious, protandrous perennial. Male steriles were used to check the estimation procedure of outcrossing rates in hermaphrodites. Estimates of outcrossing rates in

  8. On local dark matter density

    CERN Document Server

    Bidin, C Moni; Carraro, G; Mendez, R A; Moyano, M

    2014-01-01

    In 2012, we applied a three-dimensional formulation to kinematic measurements of the Galactic thick disk and derived a surprisingly low dark matter density at the solar position. This result was challenged by Bovy & Tremaine (2012, ApJ, 756, 89), who claimed that the observational data are consistent with the expected dark matter density if a one-dimensional approach is adopted. We analyze the assumption at the bases of their formulation and their claim that this returns a lower limit for the local dark matter density, which is accurate within 20%. We find that the validity of their formulation depends on the underlying mass distribution. We therefore analyze the predictions that their hypothesis casts on the radial gradient of the azimuthal velocity dV/dR and compare it with observational data as a testbed for the validity of their formulation. We find that their hypothesis requires too steep a profile of dV(Z)/dR, which is inconsistent with the observational data both in the Milky Way and in external ga...

  9. The Local Dark Matter Density

    CERN Document Server

    Read, J I

    2014-01-01

    I review current efforts to measure the mean density of dark matter near the Sun. This encodes valuable dynamical information about our Galaxy and is also of great importance for 'direct detection' dark matter experiments. I discuss theoretical expectations in our current cosmology; the theory behind mass modelling of the Galaxy; and I show how combining local and global measures probes the shape of the Milky Way dark matter halo and the possible presence of a 'dark disc'. I stress the strengths and weaknesses of different methodologies and highlight the continuing need for detailed tests on mock data - particularly in the light of recently discovered evidence for disequilibria in the Milky Way disc. I highlight several recent measurements in order of increasing data complexity and prior, and, correspondingly, decreasing formal error bars. Comparing these measurements with spherical extrapolations from the Milky Way's rotation curve, I show that the Milky Way is consistent with having a spherical dark matter ...

  10. High frame rate and high line density ultrasound imaging for local pulse wave velocity estimation using motion matching: A feasibility study on vessel phantoms.

    Science.gov (United States)

    Li, Fubing; He, Qiong; Huang, Chengwu; Liu, Ke; Shao, Jinhua; Luo, Jianwen

    2016-04-01

    Pulse wave imaging (PWI) is an ultrasound-based method to visualize the propagation of pulse wave and to quantitatively estimate regional pulse wave velocity (PWV) of the arteries within the imaging field of view (FOV). To guarantee the reliability of PWV measurement, high frame rate imaging is required, which can be achieved by reducing the line density of ultrasound imaging or transmitting plane wave at the expense of spatial resolution and/or signal-to-noise ratio (SNR). In this study, a composite, full-view imaging method using motion matching was proposed with both high temporal and spatial resolution. Ultrasound radiofrequency (RF) data of 4 sub-sectors, each with 34 beams, including a common beam, were acquired successively to achieve a frame rate of ∼507 Hz at an imaging depth of 35 mm. The acceleration profiles of the vessel wall estimated from the common beam were used to reconstruct the full-view (38-mm width, 128-beam) image sequence. The feasibility of mapping local PWV variation along the artery using PWI technique was preliminarily validated on both homogeneous and inhomogeneous polyvinyl alcohol (PVA) cryogel vessel phantoms. Regional PWVs for the three homogeneous phantoms measured by the proposed method were in accordance with the sparse imaging method (38-mm width, 32-beam) and plane wave imaging method. Local PWV was estimated using the above-mentioned three methods on 3 inhomogeneous phantoms, and good agreement was obtained in both the softer (1.91±0.24 m/s, 1.97±0.27 m/s and 1.78±0.28 m/s) and the stiffer region (4.17±0.46 m/s, 3.99±0.53 m/s and 4.27±0.49 m/s) of the phantoms. In addition to the improved spatial resolution, higher precision of local PWV estimation in low SNR circumstances was also obtained by the proposed method as compared with the sparse imaging method. The proposed method might be helpful in disease detections through mapping the local PWV of the vascular wall.

  11. GROUND-BASED Paα NARROW-BAND IMAGING OF LOCAL LUMINOUS INFRARED GALAXIES. I. STAR FORMATION RATES AND SURFACE DENSITIES

    Energy Technology Data Exchange (ETDEWEB)

    Tateuchi, Ken; Konishi, Masahiro; Motohara, Kentaro; Takahashi, Hidenori; Kato, Natsuko Mitani; Kitagawa, Yutaro; Todo, Soya; Toshikawa, Koji; Sako, Shigeyuki; Uchimoto, Yuka K.; Ohsawa, Ryou; Asano, Kentaro; Kamizuka, Takafumi; Nakamura, Tomohiko; Okada, Kazushi [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Ita, Yoshifusa [Astronomical Institute, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Komugi, Shinya [Division of Liberal Arts, Kogakuin University, 2665-1, Hachioji, Tokyo 192-0015 (Japan); Koshida, Shintaro [Subaru Telescope, National Astronomical Observatory of Japan, Hilo, HI 96720 (United States); Manabe, Sho [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Nakashima, Asami, E-mail: tateuchi@ioa.s.u-tokyo.ac.jp [Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); and others

    2015-03-15

    Luminous infrared galaxies (LIRGs) are enshrouded by a large amount of dust produced by their active star formation, and it is difficult to measure their activity in optical wavelengths. We have carried out Paα narrow-band imaging observations of 38 nearby star forming galaxies including 33 LIRGs listed in the IRAS Revised Bright Galaxy Sample catalog with the Atacama Near InfraRed camera on the University of Tokyo Atacama Observatory (TAO) 1.0 m telescope (miniTAO). Star formation rates (SFRs) estimated from the Paα fluxes, corrected for dust extinction using the Balmer decrement method (typically A{sub V} ∼ 4.3 mag), show a good correlation with those from the bolometric infrared luminosity of the IRAS data within a scatter of 0.27 dex. This suggests that the correction of dust extinction for the Paα flux is sufficient in our sample. We measure the physical sizes and surface densities of infrared luminosities (Σ{sub L(IR)}) and the SFR (Σ{sub SFR}) of star forming regions for individual galaxies, and we find that most of the galaxies follow a sequence of local ultra-luminous or luminous infrared galaxies (U/LIRGs) on the L(IR)-Σ{sub L(IR)} and SFR-Σ{sub SFR} plane. We confirm that a transition of the sequence from normal galaxies to U/LIRGs is seen at L(IR) = 8 × 10{sup 10} L {sub ☉}. Also, we find that there is a large scatter in physical size, different from normal galaxies or ULIRGs. Considering the fact that most U/LIRGs are merging or interacting galaxies, this scatter may be caused by strong external factors or differences in their merging stages.

  12. Density estimation from local structure

    CSIR Research Space (South Africa)

    Van der Walt, Christiaan M

    2009-11-01

    Full Text Available Mixture Model (GMM) density function of the data and the log-likelihood scores are compared to the scores of a GMM trained with the expectation maximization (EM) algorithm on 5 real-world classification datasets (from the UCI collection). They show...

  13. Locality of correlation in density functional theory.

    Science.gov (United States)

    Burke, Kieron; Cancio, Antonio; Gould, Tim; Pittalis, Stefano

    2016-08-07

    The Hohenberg-Kohn density functional was long ago shown to reduce to the Thomas-Fermi (TF) approximation in the non-relativistic semiclassical (or large-Z) limit for all matter, i.e., the kinetic energy becomes local. Exchange also becomes local in this limit. Numerical data on the correlation energy of atoms support the conjecture that this is also true for correlation, but much less relevant to atoms. We illustrate how expansions around a large particle number are equivalent to local density approximations and their strong relevance to density functional approximations. Analyzing highly accurate atomic correlation energies, we show that EC → -AC ZlnZ + BCZ as Z → ∞, where Z is the atomic number, AC is known, and we estimate BC to be about 37 mhartree. The local density approximation yields AC exactly, but a very incorrect value for BC, showing that the local approximation is less relevant for the correlation alone. This limit is a benchmark for the non-empirical construction of density functional approximations. We conjecture that, beyond atoms, the leading correction to the local density approximation in the large-Z limit generally takes this form, but with BC a functional of the TF density for the system. The implications for the construction of approximate density functionals are discussed.

  14. Dust Attenuation in UV-selected Starbursts at High Redshift and their Local Counterparts: Implications for the Cosmic Star Formation Rate Density

    CERN Document Server

    Overzier, Roderik; Wang, Jing; Armus, Lee; Buat, Veronique; Howell, Justin; Meurer, Gerhardt; Seibert, Mark; Siana, Brian; Basu-Zych, Antara; Charlot, Stéphane; Gonçalves, Thiago S; Martin, D Christopher; Neill, James D; Rich, R Michael; Salim, Samir; Schiminovich, David

    2010-01-01

    We present a new analysis of the dust obscuration in starburst galaxies at low and high redshift. This study is motivated by our unique sample of the most extreme UV-selected starburst galaxies in the nearby universe (z<0.3), found to be good analogs of high-redshift Lyman Break Galaxies (LBGs) in most of their physical properties. We find that the dust properties of the Lyman Break Analogs (LBAs) are consistent with the relation derived previously by Meurer et al. (M99) that is commonly used to dust-correct star formation rate measurements at a very wide range of redshifts. We directly compare our results with high redshift samples (LBGs, BzK, and sub-mm galaxies at z=2-3) having IR data either from Spitzer or Herschel. The attenuation in typical LBGs at z=2-3 and LBAs is very similar. Because LBAs are much better analogs to LBGs compared to previous local star-forming samples, including M99, the practice of dust-correcting the SFRs of high redshift galaxies based on the local calibration is now placed on...

  15. Local density approximations from finite systems

    CERN Document Server

    Entwistle, Mike; Wetherell, Jack; Longstaff, Bradley; Ramsden, James; Godby, Rex

    2016-01-01

    The local density approximation (LDA) constructed through quantum Monte Carlo calculations of the homogeneous electron gas (HEG) is the most common approximation to the exchange-correlation functional in density functional theory. We introduce an alternative set of LDAs constructed from slab-like systems of one, two and three electrons that resemble the HEG within a finite region, and illustrate the concept in one dimension. Comparing with the exact densities and Kohn-Sham potentials for various test systems, we find that the LDAs give a good account of the self-interaction correction, but are less reliable when correlation is stronger or currents flow.

  16. Ground-based Pa$\\alpha$ Narrow-band Imaging of Local Luminous Infrared Galaxies I: Star Formation Rates and Surface Densities

    CERN Document Server

    Tateuchi, Ken; Motohara, Kentaro; Takahashi, Hidenori; Kato, Natsuko Mitani; Kitagawa, Yutaro; Todo, Soya; Toshikawa, Koji; Sako, Shigeyuki; Uchimoto, Yuka K; Ohsawa, Ryou; Asano, Kentaro; Ita, Yoshifusa; Kamizuka, Takafumi; Komugi, Shinya; Koshida, Shintaro; Manabe, Sho; Nakamura, Tomohiko; Nakashima, Asami; Okada, Kazushi; Takagi, Toshinobu; Tanabé, Toshihiko; Uchiyama, Mizuho; Aoki, Tsutomu; Doi, Mamoru; Handa, Toshihiro; Kawara, Kimiaki; Kohno, Kotaro; Minezaki, Takeo; Miyata, Takashi; Morokuma, Tomoki; Soyano, Takeo; Tamura, Yoichi; Tanaka, Masuo; Tarusawa, Ken'ichi; Yoshii, Yuzuru

    2014-01-01

    Luminous infrared galaxies (LIRGs) are enshrouded by a large amount of dust, produced by their active star formation, and it is difficult to measure their activity in the optical wavelength. We have carried out Pa$\\alpha$ narrow-band imaging observations of 38 nearby star-forming galaxies including 33 LIRGs listed in $IRAS$ RBGS catalog with the Atacama Near InfraRed camera (ANIR) on the University of Tokyo Atacama Observatory (TAO) 1.0 m telescope (miniTAO). Star formation rates (SFRs) estimated from the Pa$\\alpha$ fluxes, corrected for dust extinction using the Balmer Decrement Method (typically $A_V$ $\\sim$ 4.3 mag), show a good correlation with those from the bolometric infrared luminosity of $IRAS$ data within a scatter of 0.27 dex. This suggests that the correction of dust extinction for Pa$\\alpha$ flux is sufficient in our sample. We measure the physical sizes and the surface density of infrared luminosities ($\\Sigma_{L(\\mathrm{IR})}$) and $SFR$ ($\\Sigma_{SFR}$) of star-forming region for individual ga...

  17. Limits on the local dark matter density

    Directory of Open Access Journals (Sweden)

    Read J.I.

    2012-02-01

    Full Text Available We study the systematic problems in determining the local dark matter density ρdm(R☉ from kinematics of stars in the Solar Neighbourhood, using a simulated Milky Way-like galaxy. We introduce a new unbiased method for recovering ρdm(R☉ based on the moments of the Jeans equations, combined with a Monte Carlo Markov Chain (MCMC technique and apply it to real data [1].

  18. Limits on the local dark matter density

    CERN Document Server

    Garbari, Silvia; Lake, George

    2011-01-01

    We revisit systematics in determining the local dark matter density (rho_dm) from the vertical motion of stars in the Solar Neighbourhood. Using a simulation of a Milky Way-like galaxy, we determine the data-quality required to detect the dark matter density at its expected local value. We introduce a new method for recovering rho_dm that uses moments of the Jeans equations, combined with a Monte Carlo Markov Chain technique to marginalise over the unknown parameters. Given sufficiently good data, we show that our method can recover the correct local dark matter density even in the face of disc inhomogeneities, non-isothermal tracers and a non-separable distribution function. We illustrate the power of our technique by applying it to Hipparcos data [Holmberg & Flynn 2000,2004]. We first make the assumption that the A and F star tracer populations are isothermal. This recovers rho_dm=0.003^{+0.009}_{-0.007}Msun/pc^3 (with 90 per cent confidence), consistent with previous determinations. However, the vertic...

  19. Dust Attenuation in UV-selected Starbursts at High Redshift and Their Local Counterparts: Implications for the Cosmic Star Formation Rate Density

    Science.gov (United States)

    Overzier, Roderik A.; Heckman, Timothy M.; Wang, Jing; Armus, Lee; Buat, Veronique; Howell, Justin; Meurer, Gerhardt; Seibert, Mark; Siana, Brian; Basu-Zych, Antara; Charlot, Stéphane; Gonçalves, Thiago S.; Martin, D. Christopher; Neill, James D.; Rich, R. Michael; Salim, Samir; Schiminovich, David

    2011-01-01

    We present a new analysis of the dust obscuration in starburst galaxies at low and high redshifts. This study is motivated by our unique sample of the most extreme UV-selected starburst galaxies in the nearby universe (z extinction is used to estimate the integrated, dust-corrected SFR density at z ~= 2-6.

  20. Limits on the local dark matter density

    Science.gov (United States)

    Garbari, Silvia; Read, Justin I.; Lake, George

    2011-09-01

    We revisit systematics in determining the local dark matter density ρdm from the vertical motion of stars in the solar neighbourhood. Using a simulation of a Milky Way like galaxy, we determine the data quality required to detect ρdm at its expected local value. We introduce a new method for recovering ρdm that uses moments of the Jeans equations, combined with a Markov chain Monte Carlo technique, to marginalize over the unknown parameters. Given sufficiently good data, we show that our method can recover the correct local dark matter density even in the face of disc inhomogeneities, non-isothermal tracers and a non-separable distribution function. We illustrate the power of our technique by applying it to Hipparcos data. We first make the assumption that the A- and F-star tracer populations are isothermal. This recovers ρdm= 0.003+0.009- 0.007 M⊙ pc-3 (ρdm= 0.11+0.34- 0.27 GeV cm-3, with 90 per cent confidence), consistent with previous determinations. However, the vertical dispersion profile of these tracers is poorly known. If we assume instead a non-isothermal profile similar to that of the blue disc stars from SDSS DR-7 recently measured, we obtain a fit with a very similar χ2 value, but with ρdm= 0.033+0.008- 0.009 M⊙ pc-3 (ρdm= 1.25+0.30- 0.34 GeV cm-3 with 90 per cent confidence). This highlights that it is vital to measure the vertical dispersion profile of the tracers to recover an unbiased estimate of ρdm.

  1. Quality Protein Maize Response to Nitrogen Rate and Plant Density ...

    African Journals Online (AJOL)

    Quality Protein Maize Response to Nitrogen Rate and Plant Density in the Guinea Savanna Zone of Ghana. ... protein maize (Zea mays L.) hybrid to plant density and nitrogen (N) fertilizer. ... Optimal N rate was not affected by plant density.

  2. The density field of the local Universe

    Energy Technology Data Exchange (ETDEWEB)

    Saunders, Will (Oxford Univ. (UK). Dept. of Astrophysics Queen Mary and Westfield Coll., London (UK). Astronomy Unit); Frenk, Carlos (Durham Univ. (UK). Dept. of Physics); Rowan-Robinson, Michael (Queen Mary and Westfield Coll., London (UK). Astronomy Unit) (and others)

    1991-01-03

    An all-sky redshift survey of galaxies detected by IRAS (the Infrared Astronomical Satellite) has been used to map the Universe out to 140h{sup -1} Mpc (the Hubble constant H{sub 0} identical to 100h km s{sup -1} Mpc{sup -1}). Well-known superclusters and voids are seen, as are others not previously identified. The inferred underlying distribution of density is found to be skewed to high densities (the voids are larger than the superclusters but depart less from the mean density); and there is more structure on large scales than is predicted by the standard cold dark matter theory of galaxy formation. (author).

  3. Localization in inelastic rate dependent shearing deformations

    KAUST Repository

    Katsaounis, Theodoros

    2016-09-04

    Metals deformed at high strain rates can exhibit failure through formation of shear bands, a phenomenon often attributed to Hadamard instability and localization of the strain into an emerging coherent structure. We verify formation of shear bands for a nonlinear model exhibiting strain softening and strain rate sensitivity. The effects of strain softening and strain rate sensitivity are first assessed by linearized analysis, indicating that the combined effect leads to Turing instability. For the nonlinear model a class of self-similar solutions is constructed, that depicts a coherent localizing structure and the formation of a shear band. This solution is associated to a heteroclinic orbit of a dynamical system. The orbit is constructed numerically and yields explicit shear localizing solutions. © 2016 Elsevier Ltd

  4. Dynamics of Spontaneous Emission Controlled by Local Density of States in Photonic Crystals

    DEFF Research Database (Denmark)

    Lodahl, Peter; Nikolaev, Ivan S.; van Driel, A. Floris;

    2006-01-01

    We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter.......We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter....

  5. A local leaky-box model for the local stellar surface density-gas surface density-gas phase metallicity relation

    Science.gov (United States)

    Zhu, Guangtun Ben; Barrera-Ballesteros, Jorge K.; Heckman, Timothy M.; Zakamska, Nadia L.; Sánchez, Sebastian F.; Yan, Renbin; Brinkmann, Jonathan

    2017-07-01

    We revisit the relation between the stellar surface density, the gas surface density and the gas-phase metallicity of typical disc galaxies in the local Universe with the SDSS-IV/MaNGA survey, using the star formation rate surface density as an indicator for the gas surface density. We show that these three local parameters form a tight relationship, confirming previous works (e.g. by the PINGS and CALIFA surveys), but with a larger sample. We present a new local leaky-box model, assuming star-formation history and chemical evolution is localized except for outflowing materials. We derive closed-form solutions for the evolution of stellar surface density, gas surface density and gas-phase metallicity, and show that these parameters form a tight relation independent of initial gas density and time. We show that, with canonical values of model parameters, this predicted relation match the observed one well. In addition, we briefly describe a pathway to improving the current semi-analytic models of galaxy formation by incorporating the local leaky-box model in the cosmological context, which can potentially explain simultaneously multiple properties of Milky Way-type disc galaxies, such as the size growth and the global stellar mass-gas metallicity relation.

  6. Localized density matrix minimization and linear scaling algorithms

    CERN Document Server

    Lai, Rongjie

    2015-01-01

    We propose a convex variational approach to compute localized density matrices for both zero temperature and finite temperature cases, by adding an entry-wise $\\ell_1$ regularization to the free energy of the quantum system. Based on the fact that the density matrix decays exponential away from the diagonal for insulating system or system at finite temperature, the proposed $\\ell_1$ regularized variational method provides a nice way to approximate the original quantum system. We provide theoretical analysis of the approximation behavior and also design convergence guaranteed numerical algorithms based on Bregman iteration. More importantly, the $\\ell_1$ regularized system naturally leads to localized density matrices with banded structure, which enables us to develop approximating algorithms to find the localized density matrices with computation cost linearly dependent on the problem size.

  7. The local density of optical states of a metasurface

    NARCIS (Netherlands)

    Lunnemann, P.; Koenderink, A.F.

    2016-01-01

    While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers,

  8. Galactoseismology and the Local Density of Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Banik, Nilanjan [Florida U.; Widrow, Lawrence M. [Queen' s U., Kingston; Dodelson, Scott [Fermilab

    2016-08-10

    We model vertical breathing mode perturbations in the Milky Way's stellar disc and study their effects on estimates of the local dark matter density, surface density, and vertical force. Evidence for these perturbations, which involve compression and expansion of the Galactic disc perpendicular to its midplane, come from the SEGUE, RAVE, and LAMOST surveys. We show that their existence may lead to systematic errors of $10\\%$ or greater in the vertical force $K_z(z)$ at $|z|=1.1\\,{\\rm kpc}$. These errors translate to $\\gtrsim 25\\%$ errors in estimates of the local dark matter density. Using different mono-abundant subpopulations as tracers offers a way out: if the inferences from all tracers in the Gaia era agree, then the dark matter determination will be robust. Disagreement in the inferences from different tracers will signal the breakdown of the unperturbed model and perhaps provide the means for determining the nature of the perturbation.

  9. Galactoseismology and the Local Density of Dark Matter

    CERN Document Server

    Banik, Nilanjan; Dodelson, Scott

    2016-01-01

    We model vertical breathing mode perturbations in the Milky Way's stellar disc and study their effects on estimates of the local dark matter density, surface density, and vertical force. Evidence for these perturbations, which involve compression and expansion of the Galactic disc perpendicular to its midplane, come from the SEGUE, RAVE, and LAMOST surveys. We show that their existence may lead to systematic errors of $10\\%$ or greater in the vertical force $K_z(z)$ at $|z|=1.1\\,{\\rm kpc}$. These errors translate to $\\gtrsim 25\\%$ errors in estimates of the local dark matter density. Using different mono-abundant subpopulations as tracers offers a way out: if the inferences from all tracers in the Gaia era agree, then the dark matter determination will be robust. Disagreement in the inferences from different tracers will signal the breakdown of the unperturbed model and perhaps provide the means for determining the nature of the perturbation.

  10. Weak preservation of local neutral substitution rates across mammalian genomes

    Directory of Open Access Journals (Sweden)

    Karro John E

    2009-05-01

    Full Text Available Abstract Background The rate at which neutral (non-functional bases undergo substitution is highly dependent on their location within a genome. However, it is not clear how fast these location-dependent rates change, or to what extent the substitution rate patterns are conserved between lineages. To address this question, which is critical not only for understanding the substitution process but also for evaluating phylogenetic footprinting algorithms, we examine ancestral repeats: a predominantly neutral dataset with a significantly higher genomic density than other datasets commonly used to study substitution rate variation. Using this repeat data, we measure the extent to which orthologous ancestral repeat sequences exhibit similar substitution patterns in separate mammalian lineages, allowing us to ascertain how well local substitution rates have been preserved across species. Results We calculated substitution rates for each ancestral repeat in each of three independent mammalian lineages (primate – from human/macaque alignments, rodent – from mouse/rat alignments, and laurasiatheria – from dog/cow alignments. We then measured the correlation of local substitution rates among these lineages. Overall we found the correlations between lineages to be statistically significant, but too weak to have much predictive power (r2 5%. These correlations were found to be primarily driven by regional effects at the scale of several hundred kb or larger. A few repeat classes (e.g. 7SK, Charlie8, and MER121 also exhibited stronger conservation of rate patterns, likely due to the effect of repeat-specific purifying selection. These classes should be excluded when estimating local neutral substitution rates. Conclusion Although local neutral substitution rates have some correlations among mammalian species, these correlations have little predictive power on the scale of individual repeats. This indicates that local substitution rates have changed

  11. How are mortality rates affected by population density?

    CERN Document Server

    Wang, Lei; Di, Zengru; Roehner, Bertrand M

    2013-01-01

    Biologists have found that the death rate of cells in culture depends upon their spatial density. Permanent "Stay alive" signals from their neighbours seem to prevent them from dying. In a previous paper (Wang et al. 2013) we gave evidence for a density effect for ants. In this paper we examine whether there is a similar effect in human demography. We find that although there is no observable relationship between population density and overall death rates, there is a clear relationship between density and the death rates of young age-groups. Basically their death rates decrease with increasing density. However, this relationship breaks down around 300 inhabitants per square kilometre. Above this threshold the death rates remains fairly constant. The same density effect is observed in Canada, France, Japan and the United States. We also observe a striking parallel between the density effect and the so-called marital status effect in the sense that they both lead to higher suicide rates and are both enhanced fo...

  12. The energy production rate density of cosmic rays in the local universe is $\\sim10^{44-45}\\rm erg~Mpc^{-3}~yr^{-1}$ at all particle energies

    CERN Document Server

    Katz, Boaz; Thompson, Todd; Loeb, Abraham

    2013-01-01

    The energy output (per logarithmic interval of particle energies) of Cosmic Rays (CRs) with energies $10{\\rm GeV}\\lesssim\\varepsilon_p\\lesssim100{\\rm GeV}$ is $\\sim 10^{47}\\rm erg$ per solar mass of star$-$formation, based on the CR production rate in the Milky Way and in starburst galaxies, implying a generation rate of $\\varepsilon_p^2Q\\sim 10^{45}\\rm erg~Mpc^{-3}~yr^{-1}$ in the local universe. It is only $\\sim 10$ times larger than the output, $\\varepsilon_p^2 Q=0.5\\pm0.2\\times 10^{44}\\rm erg~Mpc^{-3}~yr^{-1}$, of Ultra High Energy CRs (UHECRs) at energies $10^{10.5}{\\rm GeV}<\\varepsilon_p<10^{12}\\rm GeV$ (obtained assuming they are mostly protons), which in turn is comparable to the lower limit of $\\varepsilon_p^2 Q\\ge 0.5\\times 10^{44}\\rm erg~Mpc^{-3}~yr^{-1}$ of high energy CRs with $10^6{\\rm GeV}\\lesssim\\varepsilon_p\\lesssim 10^{8}\\rm GeV$ implied by the saturation of the Waxman-Bahcall bound by the neutrino excess recently discovered by IceCube. These similarities are consistent with a flat pro...

  13. Local Finite Density Theory, Statistical Blocking and Color Superconductivity

    CERN Document Server

    Ying, S

    2000-01-01

    The motivation for the development of a local finite density theory is discussed. One of the problems related to an instability in the baryon number fluctuation of the chiral symmetry breaking phase of the quark system in the local theory is shown to exist. Such an instability problem is removed by taking into account the statistical blocking effects for the quark propagator, which depends on a macroscopic {\\em statistical blocking parameter} $\\epsilon$. This new frame work is then applied to study color superconducting phase of the light quark system.

  14. Self-interaction corrected local spin density calculations of actinides

    DEFF Research Database (Denmark)

    Petit, Leon; Svane, Axel; Szotek, Z

    2010-01-01

    We use the self-interaction corrected local spin-density approximation in order to describe localization-delocalization phenomena in the strongly correlated actinide materials. Based on total energy considerations, the methodology enables us to predict the ground-state valency configuration...... of the actinide ions in these compounds from first principles. Here we review a number of applications, ranging from electronic structure calculations of actinide metals, nitrides and carbides to the behaviour under pressure of intermetallics, and O vacancies in PuO2....

  15. Wave Localization and Density Bunching in Pair Ion Plasmas

    CERN Document Server

    Mahajan, Swadesh M

    2008-01-01

    By investigating the nonlinear propagation of high intensity electromagnetic (EM) waves in a pair ion plasma, whose symmetry is broken via contamination by a small fraction of high mass immobile ions, it is shown that this new and interesting state of (laboratory created) matter is capable of supporting structures that strongly localize and bunch the EM radiation with density excess in the region of localization. Testing of this prediction in controlled laboratory experiments can lend credence, inter alia, to conjectures on structure formation (via the same mechanism) in the MEV era of the early universe.

  16. Beyond the local density approximation : improving density functional theory for high energy density physics applications.

    Energy Technology Data Exchange (ETDEWEB)

    Mattsson, Ann Elisabet; Modine, Normand Arthur; Desjarlais, Michael Paul; Muller, Richard Partain; Sears, Mark P.; Wright, Alan Francis

    2006-11-01

    A finite temperature version of 'exact-exchange' density functional theory (EXX) has been implemented in Sandia's Socorro code. The method uses the optimized effective potential (OEP) formalism and an efficient gradient-based iterative minimization of the energy. The derivation of the gradient is based on the density matrix, simplifying the extension to finite temperatures. A stand-alone all-electron exact-exchange capability has been developed for testing exact exchange and compatible correlation functionals on small systems. Calculations of eigenvalues for the helium atom, beryllium atom, and the hydrogen molecule are reported, showing excellent agreement with highly converged quantumMonte Carlo calculations. Several approaches to the generation of pseudopotentials for use in EXX calculations have been examined and are discussed. The difficult problem of finding a correlation functional compatible with EXX has been studied and some initial findings are reported.

  17. The Structure of the Local Interstellar Medium V: Electron Densities

    CERN Document Server

    Redfield, Seth

    2008-01-01

    We present a comprehensive survey of CII* absorption detections toward stars within 100 pc in order to measure the distribution of electron densities present in the local interstellar medium (LISM). Using high spectral resolution observations of nearby stars obtained by GHRS and STIS onboard the Hubble Space Telescope, we identify 13 sight lines with 23 individual CII* absorption components, which provide electron density measurements, the vast majority of which are new. We employ several strategies to determine more accurate CII column densities from the saturated CII resonance line, including, constraints of the line width from the optically thin CII* line, constraints from independent temperature measurements of the LISM gas based on line widths of other ions, and third, using measured SII column densities as a proxy for CII column densities. The sample of electron densities appears consistent with a log-normal distribution and an unweighted mean value of n_e(CII_SII) = 0.11^+0.10_-0.05 cm^-3. Seven indivi...

  18. Local thermodynamic mapping for effective liquid density-functional theory

    Science.gov (United States)

    Kyrlidis, Agathagelos; Brown, Robert A.

    1992-01-01

    The structural-mapping approximation introduced by Lutsko and Baus (1990) in the generalized effective-liquid approximation is extended to include a local thermodynamic mapping based on a spatially dependent effective density for approximating the solid phase in terms of the uniform liquid. This latter approximation, called the local generalized effective-liquid approximation (LGELA) yields excellent predictions for the free energy of hard-sphere solids and for the conditions of coexistence of a hard-sphere fcc solid with a liquid. Moreover, the predicted free energy remains single valued for calculations with more loosely packed crystalline structures, such as the diamond lattice. The spatial dependence of the weighted density makes the LGELA useful in the study of inhomogeneous solids.

  19. The local density of optical states of a metasurface

    CERN Document Server

    Lunnemann, Per

    2016-01-01

    While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers, i.e., the response to near field excitation by a point source. Based on a point-dipole theory using Ewald summation and an array scanning method, we can swiftly and semi-analytically evaluate the local density of states (LDOS) for magnetoelectric point sources in front of an infinite two-dimensional (2D) lattice composed of arbitrary magnetoelectric dipole scatterers. The method takes into account radiation damping as well as all retarded electrodynamic interactions in a self-consistent manner. We show that a lattice of magnetic scatterers evidences characteristic Drexhage oscillations. However, the oscillations are phase shifted relative to the electrically scattering lattice consistent with the difference expect...

  20. 40 CFR 280.104 - Local government bond rating test.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Local government bond rating test. 280... STORAGE TANKS (UST) Financial Responsibility § 280.104 Local government bond rating test. (a) A general purpose local government owner or operator and/or local government serving as a guarantor may satisfy...

  1. Dependence of Reaction Rate Constants on Density in Supercritical Fluids

    Institute of Scientific and Technical Information of China (English)

    WANGTao; SHENZhongyao

    2002-01-01

    A new method,which correlates rate constants of chemical reactions and density or pressure in supercritical fluids,was developed.Based on the transition state theory and thermodynamic principles, the rate constant can be reasonably correlated with the density of the supercritical fluid,and a correlation equation was obtained. Coupled with the equation of state (EOS) of a supercritical solvent,the effect of pressure on reaction rate constant could be represented.Two typical systems were used to test this method.The result indicates that this method is suitable for dilute supercritical fluid solutions.

  2. Galactoseismology and the local density of dark matter

    Science.gov (United States)

    Banik, Nilanjan; Widrow, Lawrence M.; Dodelson, Scott

    2017-02-01

    We model vertical breathing mode perturbations in the Milky Way's stellar disc and study their effects on estimates of the local dark matter density, surface density, and vertical force. Evidence for these perturbations, which involve compression and expansion of the Galactic disc perpendicular to the mid-plane, comes from three different surveys of stellar kinematics within a few kiloparsecs of the Sun. We show that their existence may lead to systematic errors of 10 per cent or greater in the vertical force Kz(z) at |z| = 1.1 kpc. These errors translate to ≳ 25 per cent errors in estimates of the local dark matter density. Using different mono-abundant subpopulations as tracers offers a way out: if the inferences from all tracers in the Gaia era agree, then the dark matter determination will be robust. Disagreement in the inferences from different tracers will signal the breakdown of the unperturbed model and perhaps provide the means for determining the nature of the perturbation.

  3. Experimental Tests of Local Cosmological Expansion Rates

    CERN Document Server

    Widom, A; Srivastava, Y

    2015-01-01

    Cosmological expansion on a local scale is usually neglected in part due to its smallness, and in part due to components of bound systems (especially those bound by non-gravitational forces such as atoms and nuclei) not following the geodesics of the cosmological metric. However, it is interesting to ask whether or not experimental tests of cosmological expansion on a local scale (well within our own galaxy) might be experimentally accessible in some manner. We point out, using the Pioneer satellites as an example, that current satellite technology allows for this possibility within time scales of less than one human lifetime.

  4. Measurement of local current density of all-vanadium redox flow batteries

    Science.gov (United States)

    Hsieh, Wen-Yen; Leu, Chih-Hsing; Wu, Chun-Hsing; Chen, Yong-Song

    2014-12-01

    This article presents a preliminary study of the measurement of local current density in all-vanadium redox flow batteries. Two batteries are designed and manufactured in this study, and the experimental results are compared. In the first cell, the current collector is divided into 25 segments, and the flow field plate is not segmented, whereas in the other cell, the flow field plate is segmented. The effects of the electrolyte flow rate on the battery efficiencies and the local current density variation are investigated. The experimental results show that the current density near the outlet significantly decreases when the discharge capacity approaches zero. In addition, the battery has a larger discharge depth at a higher electrolyte flow rate.

  5. Single crystal plasticity by modeling dislocation density rate behavior

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Benjamin L [Los Alamos National Laboratory; Bronkhorst, Curt [Los Alamos National Laboratory; Beyerlein, Irene [Los Alamos National Laboratory; Cerreta, E. K. [Los Alamos National Laboratory; Dennis-Koller, Darcie [Los Alamos National Laboratory

    2010-12-23

    The goal of this work is to formulate a constitutive model for the deformation of metals over a wide range of strain rates. Damage and failure of materials frequently occurs at a variety of deformation rates within the same sample. The present state of the art in single crystal constitutive models relies on thermally-activated models which are believed to become less reliable for problems exceeding strain rates of 10{sup 4} s{sup -1}. This talk presents work in which we extend the applicability of the single crystal model to the strain rate region where dislocation drag is believed to dominate. The elastic model includes effects from volumetric change and pressure sensitive moduli. The plastic model transitions from the low-rate thermally-activated regime to the high-rate drag dominated regime. The direct use of dislocation density as a state parameter gives a measurable physical mechanism to strain hardening. Dislocation densities are separated according to type and given a systematic set of interactions rates adaptable by type. The form of the constitutive model is motivated by previously published dislocation dynamics work which articulated important behaviors unique to high-rate response in fcc systems. The proposed material model incorporates thermal coupling. The hardening model tracks the varying dislocation population with respect to each slip plane and computes the slip resistance based on those values. Comparisons can be made between the responses of single crystals and polycrystals at a variety of strain rates. The material model is fit to copper.

  6. The local density of optical states of a metasurface

    Science.gov (United States)

    Lunnemann, Per; Koenderink, A. Femius

    2016-02-01

    While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers, i.e., the response to near field excitation by a point source. Based on a pointdipole theory using Ewald summation and an array scanning method, we can swiftly and semi-analytically evaluate the local density of states (LDOS) for magnetoelectric point sources in front of an infinite two-dimensional (2D) lattice composed of arbitrary magnetoelectric dipole scatterers. The method takes into account radiation damping as well as all retarded electrodynamic interactions in a self-consistent manner. We show that a lattice of magnetic scatterers evidences characteristic Drexhage oscillations. However, the oscillations are phase shifted relative to the electrically scattering lattice consistent with the difference expected for reflection off homogeneous magnetic respectively electric mirrors. Furthermore, we identify in which source-surface separation regimes the metasurface may be treated as a homogeneous interface, and in which homogenization fails. A strong frequency and in-plane position dependence of the LDOS close to the lattice reveals coupling to guided modes supported by the lattice.

  7. The LC resonance probe for determining local plasma density

    Energy Technology Data Exchange (ETDEWEB)

    Boris, D R; Fernsler, R F; Walton, S G, E-mail: david.boris.ctr@nrl.navy.mi [Naval Research Laboratory, Charge Particle Physics Branch-Code 6752, Plasma Physics Division, 4555 Overlook Ave. SW, Washington, DC 20375 (United States)

    2011-04-15

    We present a novel plasma diagnostic for measuring local plasma density in reactive-gas plasmas, and depositing plasmas. The diagnostic uses a network analyzer to measure the LC resonance (LCR) frequency of a parallel plate capacitor with inductive leads. The location of the LCR ({omega}{sub R}) in frequency space is then used as a measure of the plasma dielectric constant bold varepsilon{sub p} between the plates. By properly constructing the LCR probe, {omega}{sub R} can be tuned such that {omega}{sub R} >> {omega}{sub ce}, where {omega}{sub ce} is the electron-cyclotron frequency. Thus, the probe can be used in plasmas with varying degrees of magnetization while avoiding complications introduced to bold varepsilon{sub p} when {omega} is comparable to {omega}{sub ce}. Density measurements from the LCR probe are compared with Langmuir probe measurements in an electron-beam generated plasma in which density varied from 10{sup 9} to 10{sup 11} cm{sup -3}. An axial magnetic field, typically used to confine the electron beam, was varied between 0 to 300 G. The LCR probe showed good agreement with a Langmuir probe across the entire range of magnetic fields.

  8. Global and local curvature in density functional theory

    Science.gov (United States)

    Zhao, Qing; Ioannidis, Efthymios I.; Kulik, Heather J.

    2016-08-01

    Piecewise linearity of the energy with respect to fractional electron removal or addition is a requirement of an electronic structure method that necessitates the presence of a derivative discontinuity at integer electron occupation. Semi-local exchange-correlation (xc) approximations within density functional theory (DFT) fail to reproduce this behavior, giving rise to deviations from linearity with a convex global curvature that is evidence of many-electron, self-interaction error and electron delocalization. Popular functional tuning strategies focus on reproducing piecewise linearity, especially to improve predictions of optical properties. In a divergent approach, Hubbard U-augmented DFT (i.e., DFT+U) treats self-interaction errors by reducing the local curvature of the energy with respect to electron removal or addition from one localized subshell to the surrounding system. Although it has been suggested that DFT+U should simultaneously alleviate global and local curvature in the atomic limit, no detailed study on real systems has been carried out to probe the validity of this statement. In this work, we show when DFT+U should minimize deviations from linearity and demonstrate that a "+U" correction will never worsen the deviation from linearity of the underlying xc approximation. However, we explain varying degrees of efficiency of the approach over 27 octahedral transition metal complexes with respect to transition metal (Sc-Cu) and ligand strength (CO, NH3, and H2O) and investigate select pathological cases where the delocalization error is invisible to DFT+U within an atomic projection framework. Finally, we demonstrate that the global and local curvatures represent different quantities that show opposing behavior with increasing ligand field strength, and we identify where these two may still coincide.

  9. The relation between star formation, morphology and local density in high redshift clusters and groups

    CERN Document Server

    Poggianti, Bianca M; Finn, Rose; Bamford, Steven; De Lucia, Gabriella; Varela, Jesus; Aragon-Salamanca, Alfonso; Halliday, Claire; Noll, Stefan; Saglia, Roberto; Zaritsky, Dennis; Best, Philip; Clowe, Douglas; Milvang-Jensen, Bo; Jablonka, Pascale; Pello, Roser; Rudnick, Gregory; Simard, Luc; von der Linden, Anja; White, Simon

    2008-01-01

    We investigate how the [OII] properties and the morphologies of galaxies in clusters and groups at z=0.4-0.8 depend on projected local galaxy density, and compare with the field at similar redshifts and clusters at low-z. In both nearby and distant clusters, higher-density regions contain proportionally fewer star-forming galaxies, and the average [OII] equivalent width of star-forming galaxies is independent of local density. However, in distant clusters the average current star formation rate (SFR) in star-forming galaxies seems to peak at densities ~15-40 galaxies Mpc^{-2}. At odds with low-z results, at high-z the relation between star-forming fraction and local density varies from high- to low-mass clusters. Overall, our results suggest that at high-z the current star formation (SF) activity in star-forming galaxies does not depend strongly on global or local environment, though the possible SFR peak seems at odds with this conclusion. We find that the cluster SFR normalized by cluster mass anticorrelate...

  10. Density dependence, whitebark pine, and vital rates of grizzly bears

    Science.gov (United States)

    van Manen, Frank T.; Haroldson, Mark A.; Bjornlie, Daniel D; Ebinger, Michael R.; Thompson, Daniel J.; Costello, Cecily M; White, Gary C.

    2016-01-01

    Understanding factors influencing changes in population trajectory is important for effective wildlife management, particularly for populations of conservation concern. Annual population growth of the grizzly bear (Ursus arctos) population in the Greater Yellowstone Ecosystem, USA has slowed from 4.2–7.6% during 1983–2001 to 0.3–2.2% during 2002–2011. Substantial changes in availability of a key food source and bear population density have occurred. Whitebark pine (Pinus albicaulis), the seeds of which are a valuable but variable fall food for grizzly bears, has experienced substantial mortality primarily due to a mountain pine beetle (Dendroctonus ponderosae) outbreak that started in the early 2000s. Positive growth rates of grizzly bears have resulted in populations reaching high densities in some areas and have contributed to continued range expansion. We tested research hypotheses to examine if changes in vital rates detected during the past decade were more associated with whitebark pine decline or, alternatively, increasing grizzly bear density. We focused our assessment on known-fate data to estimate survival of cubs-of-the-year (cubs), yearlings, and independent bears (≥2 yrs), and reproductive transition of females from having no offspring to having cubs. We used spatially and temporally explicit indices for grizzly bear density and whitebark pine mortality as individual covariates. Models indicated moderate support for an increase in survival of independent male bears over 1983–2012, whereas independent female survival did not change. Cub survival, yearling survival, and reproductive transition from no offspring to cubs all changed during the 30-year study period, with lower rates evident during the last 10–15 years. Cub survival and reproductive transition were negatively associated with an index of grizzly bear density, indicating greater declines where bear densities were higher. Our analyses did not support a similar relationship for the

  11. Dissecting the roles of local packing density and longer-range effects in protein sequence evolution.

    Science.gov (United States)

    Shahmoradi, Amir; Wilke, Claus O

    2016-06-01

    What are the structural determinants of protein sequence evolution? A number of site-specific structural characteristics have been proposed, most of which are broadly related to either the density of contacts or the solvent accessibility of individual residues. Most importantly, there has been disagreement in the literature over the relative importance of solvent accessibility and local packing density for explaining site-specific sequence variability in proteins. We show that this discussion has been confounded by the definition of local packing density. The most commonly used measures of local packing, such as contact number and the weighted contact number, represent the combined effects of local packing density and longer-range effects. As an alternative, we propose a truly local measure of packing density around a single residue, based on the Voronoi cell volume. We show that the Voronoi cell volume, when calculated relative to the geometric center of amino-acid side chains, behaves nearly identically to the relative solvent accessibility, and each individually can explain, on average, approximately 34% of the site-specific variation in evolutionary rate in a data set of 209 enzymes. An additional 10% of variation can be explained by nonlocal effects that are captured in the weighted contact number. Consequently, evolutionary variation at a site is determined by the combined effects of the immediate amino-acid neighbors of that site and effects mediated by more distant amino acids. We conclude that instead of contrasting solvent accessibility and local packing density, future research should emphasize on the relative importance of immediate contacts and longer-range effects on evolutionary variation. Proteins 2016; 84:841-854. © 2016 Wiley Periodicals, Inc.

  12. Pair 2-electron reduced density matrix theory using localized orbitals

    Science.gov (United States)

    Head-Marsden, Kade; Mazziotti, David A.

    2017-08-01

    Full configuration interaction (FCI) restricted to a pairing space yields size-extensive correlation energies but its cost scales exponentially with molecular size. Restricting the variational two-electron reduced-density-matrix (2-RDM) method to represent the same pairing space yields an accurate lower bound to the pair FCI energy at a mean-field-like computational scaling of O (r3) where r is the number of orbitals. In this paper, we show that localized molecular orbitals can be employed to generate an efficient, approximately size-extensive pair 2-RDM method. The use of localized orbitals eliminates the substantial cost of optimizing iteratively the orbitals defining the pairing space without compromising accuracy. In contrast to the localized orbitals, the use of canonical Hartree-Fock molecular orbitals is shown to be both inaccurate and non-size-extensive. The pair 2-RDM has the flexibility to describe the spectra of one-electron RDM occupation numbers from all quantum states that are invariant to time-reversal symmetry. Applications are made to hydrogen chains and their dissociation, n-acene from naphthalene through octacene, and cadmium telluride 2-, 3-, and 4-unit polymers. For the hydrogen chains, the pair 2-RDM method recovers the majority of the energy obtained from similar calculations that iteratively optimize the orbitals. The localized-orbital pair 2-RDM method with its mean-field-like computational scaling and its ability to describe multi-reference correlation has important applications to a range of strongly correlated phenomena in chemistry and physics.

  13. The local density of optical states of a metasurface

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann; Koenderink, A. Femius

    2016-01-01

    While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers......-dimensional (2D) lattice composed of arbitrary magnetoelectric dipole scatterers. The method takes into account radiation damping as well as all retarded electrodynamic interactions in a self-consistent manner. We show that a lattice of magnetic scatterers evidences characteristic Drexhage oscillations. However......, the oscillations are phase shifted relative to the electrically scattering lattice consistent with the difference expected for reflection off homogeneous magnetic respectively electric mirrors. Furthermore, we identify in which source-surface separation regimes the metasurface may be treated as a homogeneous...

  14. Area density of localization-entropy I: the case of wedge-localization

    Energy Technology Data Exchange (ETDEWEB)

    Schroer, Bert

    2006-04-15

    Using an appropriately formulated holographic light front projection, we derive an area law for the localization-entropy caused by vacuum polarization on the horizon of a wedge region. Its area density has a simple kinematic relation to the heat bath entropy of the light front algebra. Apart from a change of parametrization the infinite light like length contribution to the light front volume factor corresponds to the short-distance divergence of the area density of the localization entropy. This correspondence is a consequence of the conformal invariance of the light front holography combined with the well-known fact that in conformality relates short to long distances. In the explicit calculation of the strength factor we use the temperature duality relation of rational chiral theories whose derivation will be briefly reviewed. We comment on the potential relevance for the understanding of Black hole entropy. (author)

  15. Recovering Risk-Neutral Densities from Brazilian Interest Rate Options

    Directory of Open Access Journals (Sweden)

    José Renato Haas Ornelas

    2011-03-01

    Full Text Available Building Risk-Neutral Density (RND from options data is one useful way for extracting market expectations about a financial variable. For a sample of IDI (Brazilian Interbank Deposit Rate Index options from 1998 to 2009, this paper estimates the option-implied Risk-Neutral Densities for the Brazilian short rate using three methods: Shimko, Mixture of Two Log-Normals and Generalized Beta of Second Kind. Our in-sample goodness-of-fit evaluation shows that the Mixture of Log-Normals method provides better fitting to option’s data than the other two methods. The shape of log-normal distributions seems to fit well to the mean-reversal dynamics of Brazilian interest rates. We have also calculated the RND implied Skewness, showing how it could have provided market early-warning signals of the monetary policy outcomes in 2002 and 2003. Overall, Risk-Neutral Densities implied on IDI options showed to be a useful tool for extracting market expectations about future outcomes of the monetary policy.

  16. Observation of spatial fluctuations of the local density of states in random photonic media.

    Science.gov (United States)

    Birowosuto, M D; Skipetrov, S E; Vos, W L; Mosk, A P

    2010-07-02

    We experimentally study spatial fluctuations of the local density of states (LDOS) inside three-dimensional random photonic media. The LDOS is probed at many positions inside random photonic media by measuring emission rates of a large number of individual fluorescent nanospheres. The emission rates are observed to fluctuate spatially, and the variance of the fluctuations increases with the scattering strength. The measured variance of the emission rates agrees well with a model that takes into account the effect of the nearest scatterer only.

  17. Rates, Flux Densities, and Spectral Indices of Meteor Radio Afterglows

    CERN Document Server

    Obenberger, K S; Hancock, P J; Holmes, J M; Pedersen, T R; Schinzel, F K; Taylor, G B

    2016-01-01

    Using the narrowband all-sky imager mode of the LWA1 we have now detected 30 transients at 25.6 MHz, 1 at 34 MHz, and 93 at 38.0 MHz. While we have only optically confirmed that 37 of these events are radio afterglows from meteors, evidence suggests that most, if not all, are. Using the beam-forming mode of the LWA1 we have also captured the broadband spectra between 22.0 and 55.0 MHz of four events. We compare the smooth, spectral components of these four events and fit the frequency dependent flux density to a power law, and find that the spectral index is time variable, with the spectrum steepening over time for each meteor afterglow. Using these spectral indices along with the narrow band flux density measurements of the 123 events at 25.6 and 38 MHz, we predict the expected flux densities and rates for meteor afterglows potentially observable by other low frequency radio telescopes.

  18. Synaptic Ribbons Require Ribeye for Electron Density, Proper Synaptic Localization, and Recruitment of Calcium Channels

    Directory of Open Access Journals (Sweden)

    Caixia Lv

    2016-06-01

    Full Text Available Synaptic ribbons are structures made largely of the protein Ribeye that hold synaptic vesicles near release sites in non-spiking cells in some sensory systems. Here, we introduce frameshift mutations in the two zebrafish genes encoding for Ribeye and thus remove Ribeye protein from neuromast hair cells. Despite Ribeye depletion, vesicles collect around ribbon-like structures that lack electron density, which we term “ghost ribbons.” Ghost ribbons are smaller in size but possess a similar number of smaller vesicles and are poorly localized to synapses and calcium channels. These hair cells exhibit enhanced exocytosis, as measured by capacitance, and recordings from afferent neurons post-synaptic to hair cells show no significant difference in spike rates. Our results suggest that Ribeye makes up most of the synaptic ribbon density in neuromast hair cells and is necessary for proper localization of calcium channels and synaptic ribbons.

  19. The COSMOS [OII] Survey: Evolution of Electron Density with Star Formation Rate

    CERN Document Server

    Kaasinen, Melanie; Groves, Brent; Kewley, Lisa; Gupta, Anshu

    2016-01-01

    Star-forming galaxies at $z > 1$ exhibit significantly different properties to local galaxies of equivalent stellar mass. Not only are high-redshift star-forming galaxies characterized by higher star formation rates and gas fractions than their local counterparts, they also appear to host star-forming regions with significantly different physical conditions, including greater electron densities. To understand what physical mechanisms are responsible for the observed evolution of star-forming conditions we have assembled the largest sample of star-forming galaxies at $z\\sim 1.5$ with emission-line measurements of the $\\mathrm{[OII]} \\lambda \\lambda 3726,3729$ doublet. By comparing our $z\\sim 1.5$ sample to local galaxy samples with equivalent distributions of stellar mass, star formation rate and specific star formation rate we investigate the proposed evolution in electron density and its dependence on global properties. We measure an average electron density of $114_{-27}^{+28} \\, \\mathrm {cm}^{-3} $ for our...

  20. Routing Strategy Based on Local Density Sensing in Delay Tolerant Network

    Directory of Open Access Journals (Sweden)

    Fucai Wang

    2014-02-01

    Full Text Available Aiming at the interval connectivity and the limitation of available storage and internodes throughput in delay tolerant network, this paper designs a kind of Density-Aware Routing Scheme (DARS for its messaging service. According to the density of nodes, the direction that messages are forwarded to the dense area is decided. The change of correlation time between networks is used to evaluate local density and decide how to exchange information with a certain node met in the process of moving. Simulation results show that the proposed scheme has simplicity and low complexity. In the delay tolerant network of non-uniform node distribution, the message transfer rate and communication overhead get fairly good effect.

  1. Comparison of sweat rate during graded exercise and the local rate induced by pilocarpine

    Directory of Open Access Journals (Sweden)

    Vimieiro-Gomes A.C.

    2005-01-01

    Full Text Available Centrally stimulated sweat rate produced by graded exercise until exhaustion was compared to the local sweat rate induced by pilocarpine, often used as a sweating index for healthy individuals. Nine young male volunteers (22 ± 4 years were studied in temperate environment in two situations: at rest and during progressive exercise with 25 W increases every 2 min until exhaustion, on a cycle ergometer. In both situations, sweating was induced on the right forearm with 5 ml 0.5% pilocarpine hydrochloride applied by iontophoresis (1.5 mA, 5 min, with left forearm used as control. Local sweat rate was measured for 15 min at rest. During exercise, whole-body sweat rate was calculated from the body weight variation. Local sweat rate was measured from the time when heart rate reached 150 bpm until exhaustion and was collected using absorbent filter paper. Pharmacologically induced local sweat rate at rest (0.4 ± 0.2 mg cm-2 min-1 and mean exercise-induced whole-body sweat rate (0.4 ± 0.1 mg cm-2 min-1 were the same (P > 0.05 but were about five times smaller than local exercise-induced sweat rate (control = 2.1 ± 1.4; pilocarpine = 2.7 ± 1.2 mg cm-2 min-1, indicating different sudorific mechanisms. Both exercise-induced whole-body sweat rate (P < 0.05 and local sweat rate (P < 0.05 on control forearm correlated positively with pilocarpine-induced local sweat rate at rest. Assuming that exercise-induced sweating was a result of integrated physiological mechanisms, we suggest that local and whole-body sweat rate measured during graded exercise could be a better sweating index than pilocarpine.

  2. Superfluid LDA (SLDA): Local Density Approximation for Systems with Superfluid Correlations

    CERN Document Server

    Bulgac, A; Bulgac, Aurel; Yu, Yongle

    2004-01-01

    We present a concise account of our development of the first genuine Local Density Approximation (LDA) to the Energy Density Functional (EDF) for fermionic systems with superfluid correlations, with a particular emphasis to nuclear systems.

  3. High regression rate, high density hybrid fuels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR program will investigate high energy density novel nanofuels combined with high density binders for use with an N2O oxidizer. Terves has developed...

  4. PREDICTION OF MAXIMUM DRY DENSITY OF LOCAL GRANULAR ...

    African Journals Online (AJOL)

    methods. A test on a soil of relatively high solid density revealed that the developed relation looses ... where, Pd max is the laboratory maximum dry ... Addis-Jinima Road Rehabilitation. ..... data sets that differ considerably in the magnitude.

  5. A relationship between the weighted density approximation and the local-scaling transformation version of density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Diez, Reinaldo Pis [CEQUINOR, Centro de Quimica Inorganica (CONICET, UNLP), Departamento de Quimica, Facultad de Ciencias Exactas, UNLP CC 962, B1900AVV La Plata (Argentina); Karasiev, Valentin V [Centro de Qimica, Instituto Venezolano de Investigaciones Cientificas, IVIC, Apartado 21827, Caracas 1020-A (Venezuela)

    2003-07-14

    A relationship between the auxiliary density, {rho}(r), defined within the framework of the weighted density approximation and the kinetic energy modulating factor, A{sub N}([{rho}(r)]; r), which appears in the local-scaling transformation version of density functional theory is presented. This relationship imposes the condition of positiveness on the kinetic energy modulating factor and this, in turn, leads to an important mathematical condition on any approximate kinetic energy density functional. It is shown that two well-known approximate kinetic energy density functionals do not satisfy the above relationship at distances very close to the nucleus. By forcing a given approximate kinetic energy density functional to obey the above condition, both the kinetic and exchange energies can be obtained within a framework similar to that of the weighted density approximation. Results on some closed-shell atomic systems provide support for those ideas.

  6. Rates versus Developer Contributions as Revenue Sources for Local Government

    Directory of Open Access Journals (Sweden)

    Kate Koutifaris

    2012-12-01

    Full Text Available Population expansion in many New South Wales (NSW local government areas (LGA has resulted in an increase in demand for local infrastructure and services that has far outstripped sources of local government revenue. This paper looks at two important sources of local government revenue in NSW, municipal rates and Section 94 contributions, as a source of funding increased demand and maintenance of infrastructure. It examines some recent and potentially long-term trends of both these revenues within different economic climates. An analysis and comparison of data over the period from June 2006 through to June 2010 against data collected for the period ending June 1993 forms the basis of this research. The research objective is to compare changes in the relativity of these revenue types and assess their application as a source of local government revenue. Data collected from the Department of Local Government NSW is compared with the findings of an earlier study, conducted by Barnes and Dollery (1996, in determining their relativity. The provision and maintenance of infrastructure by local government is essential for growth in the economy and is a valuable asset to be used by the community. Two types of funding for this infrastructure, among others, is sourced from municipal rates and developer charges levied under Section 94 contributions either by the developer providing the infrastructure, or a contribution towards its funding (Barnes and Dollery 1996.

  7. Rates versus Developer Contributions as Revenue Sources for Local Government

    Directory of Open Access Journals (Sweden)

    Kate Koutifaris

    2012-12-01

    Full Text Available Population expansion in many New South Wales (NSW local government areas (LGA has resulted in an increase in demand for local infrastructure and services that has far outstripped sources of local government revenue. This paper looks at two important sources of local government revenue in NSW, municipal rates and Section 94 contributions, as a source of funding increased demand and maintenance of infrastructure. It examines some recent and potentially long-term trends of both these revenues within different economic climates. An analysis and comparison of data over the period from June 2006 through to June 2010 against data collected for the period ending June 1993 forms the basis of this research. The research objective is to compare changes in the relativity of these revenue types and assess their application as a source of local government revenue. Data collected from the Department of Local Government NSW is compared with the findings of an earlier study, conducted by Barnes and Dollery (1996, in determining their relativity. The provision and maintenance of infrastructure by local government is essential for growth in the economy and is a valuable asset to be used by the community. Two types of funding for this infrastructure, among others, is sourced from municipal rates and developer charges levied under Section 94 contributions either by the developer providing the infrastructure, or a contribution towards its funding (Barnes and Dollery 1996.

  8. Dynamics of localized particles from density functional theory

    Science.gov (United States)

    Reinhardt, J.; Brader, J. M.

    2012-01-01

    A fundamental assumption of the dynamical density functional theory (DDFT) of colloidal systems is that a grand-canonical free-energy functional may be employed to generate the thermodynamic driving forces. Using one-dimensional hard rods as a model system, we analyze the validity of this key assumption and show that unphysical self-interactions of the tagged particle density fields, arising from coupling to a particle reservoir, are responsible for the excessively fast relaxation predicted by the theory. Moreover, our findings suggest that even employing a canonical functional would not lead to an improvement for many-particle systems, if only the total density is considered. We present several possible schemes to suppress these effects by incorporating tagged densities. When applied to confined systems, we demonstrate, using a simple example, that DDFT necessarily leads to delocalized tagged particle density distributions, which do not respect the fundamental geometrical constraints apparent in Brownian dynamics simulation data. The implication of these results for possible applications of DDFT to treat the glass transition are discussed.

  9. Probing the Electromagnetic Local Density of States with a Strongly Mixed Electric and Magnetic Dipole Emitter

    CERN Document Server

    Karaveli, Sinan; Zia, Rashid

    2013-01-01

    We identify a solid-state quantum emitter whose room-temperature radiative decay is mediated by a nearly equal mixture of isotropic electric dipole (ED) and magnetic dipole (MD) transitions. Using energy-momentum spectroscopy, we experimentally show that the near-infrared $^3$T$_2{\\rightarrow}^3$A$_2$ emission from divalent-nickel-doped magnesium oxide (Ni$^{2+}$:MgO) is composed of $\\sim$50% MD and $\\sim$50% ED transitions. We then demonstrate that the spontaneous emission rate of these ions near planar interfaces is determined by the combined electric and magnetic local density of optical states (LDOS). This electromagnetic LDOS probes the total mode density, and thus similar to thermal emission, these unique electronic emitters effectively excite all polarizations and orientations of the electromagnetic field.

  10. Chitosan Nanoparticles for Nuclear Targeting: The Effect of Nanoparticle Size and Nuclear Localization Sequence Density.

    Science.gov (United States)

    Tammam, Salma N; Azzazy, Hassan M E; Breitinger, Hans G; Lamprecht, Alf

    2015-12-07

    Many recently discovered therapeutic proteins exert their main function in the nucleus, thus requiring both efficient uptake and correct intracellular targeting. Chitosan nanoparticles (NPs) have attracted interest as protein delivery vehicles due to their biocompatibility and ability to escape the endosomes offering high potential for nuclear delivery. Molecular entry into the nucleus occurs through the nuclear pore complexes, the efficiency of which is dependent on NP size and the presence of nuclear localization sequence (NLS). Chitosan nanoparticles of different sizes (S-NPs ≈ 25 nm; L-NP ≈ 150 nm) were formulated, and they were modified with different densities of the octapeptide NLS CPKKKRKV (S-NPs, 0.25, 0.5, 2.0 NLS/nm(2); L-NPs, 0.6, 0.9, 2 NLS/nm(2)). Unmodified and NLS-tagged NPs were evaluated for their protein loading capacity, extent of cell association, cell uptake, cell surface binding, and finally nuclear delivery efficiency in L929 fibroblasts. To avoid errors generated with cell fractionation and nuclear isolation protocols, nuclear delivery was assessed in intact cells utilizing Förster resonance energy transfer (FRET) fluorometry and microscopy. Although L-NPs showed ≈10-fold increase in protein loading per NP when compared to S-NPs, due to higher cell association and uptake S-NPs showed superior protein delivery. NLS exerts a size and density dependent effect on nanoparticle uptake and surface binding, with a general reduction in NP cell surface binding and an increase in cell uptake with the increase in NLS density (up to 8.4-fold increase in uptake of High-NLS-L-NPs (2 NLS/nm(2)) compared to unmodified L-NPs). However, for nuclear delivery, unmodified S-NPs show higher nuclear localization rates when compared to NLS modified NPs (up to 5-fold by FRET microscopy). For L-NPs an intermediate NLS density (0.9 NLS/nm(2)) seems to provide highest nuclear localization (3.7-fold increase in nuclear delivery compared to High

  11. Volumetric magnetic resonance imaging classification for Alzheimer's disease based on kernel density estimation of local features

    Institute of Scientific and Technical Information of China (English)

    YAN Hao; WANG Hu; WANG Yong-hui; ZHANG Yu-mei

    2013-01-01

    Background The classification of Alzheimer's disease (AD) from magnetic resonance imaging (MRI) has been challenged by lack of effective and reliable biomarkers due to inter-subject variability.This article presents a classification method for AD based on kernel density estimation (KDE) of local features.Methods First,a large number of local features were extracted from stable image blobs to represent various anatomical patterns for potential effective biomarkers.Based on distinctive descriptors and locations,the local features were robustly clustered to identify correspondences of the same underlying patterns.Then,the KDE was used to estimate distribution parameters of the correspondences by weighting contributions according to their distances.Thus,biomarkers could be reliably quantified by reducing the effects of further away correspondences which were more likely noises from inter-subject variability.Finally,the Bayes classifier was applied on the distribution parameters for the classification of AD.Results Experiments were performed on different divisions of a publicly available database to investigate the accuracy and the effects of age and AD severity.Our method achieved an equal error classification rate of 0.85 for subject aged 60-80 years exhibiting mild AD and outperformed a recent local feature-based work regardless of both effects.Conclusions We proposed a volumetric brain MRI classification method for neurodegenerative disease based on statistics of local features using KDE.The method may be potentially useful for the computer-aided diagnosis in clinical settings.

  12. Local fluctuations in the relaxation rate in a glassy system

    Science.gov (United States)

    Pandit, Rajib; Flenner, Elijah; Castillo, Horacio E.

    We numerically study the equilibrium dynamics of a glass-forming binary hard-sphere mixture, for different packing fractions. We extract a correlator that probes the integrated fluctuations in the local relaxation rate in the system. We find that the strength of this correlator at t =τα (the α-relaxation time) grows with packing fraction approximately as a power of τα. We also find that for a fixed packing fraction, the correlator grows as a power of time, for very long times, with an exponent that depends on the packing fraction. This exponent probes the time correlations of the relaxation rate fluctuations. We find that the exponent is around 3 for very low packing fractions, and gradually decreases to a value below 2 as the glass transition is approached. We conclude that a description of fluctuations in terms of local relaxation rates is only applicable at long times and for packing fractions close to the glass transition.

  13. Dissecting the roles of local packing density and longer-range effects in protein sequence evolution

    CERN Document Server

    Shahmoradi, Amir

    2015-01-01

    What are the structural determinants of protein sequence evolution? A number of site-specific structural characteristics have been proposed, most of which are broadly related to either the density of contacts or the solvent accessibility of individual residues. Most importantly, there has been disagreement in the literature over the relative importance of solvent accessibility and local packing density for explaining site-specific sequence variability in proteins. We show here that this discussion has been confounded by the definition of local packing density. The most commonly used measures of local packing, such as the contact number and the weighted contact number, represent by definition the combined effects of local packing density and longer-range effects. As an alternative, we here propose a truly local measure of packing density around a single residue, based on the Voronoi cell volume. We show that the Voronoi cell volume, when calculated relative to the geometric center of amino-acid side chains, be...

  14. Local kinetic-energy density of the Airy gas

    DEFF Research Database (Denmark)

    Vitos, Levente; Johansson, B.; Kollár, J.

    2000-01-01

    The Airy gas model is used to derive an expression for the local kinetic energy in the linear potential approximation. The expression contains an explicit Laplacian term 2/5((h) over bar(2)/2m)del(mu)(2)(r) that, according to jellium surface calculations, must be a universal feature of any accura...

  15. Estimating monotonic rates from biological data using local linear regression.

    Science.gov (United States)

    Olito, Colin; White, Craig R; Marshall, Dustin J; Barneche, Diego R

    2017-03-01

    Accessing many fundamental questions in biology begins with empirical estimation of simple monotonic rates of underlying biological processes. Across a variety of disciplines, ranging from physiology to biogeochemistry, these rates are routinely estimated from non-linear and noisy time series data using linear regression and ad hoc manual truncation of non-linearities. Here, we introduce the R package LoLinR, a flexible toolkit to implement local linear regression techniques to objectively and reproducibly estimate monotonic biological rates from non-linear time series data, and demonstrate possible applications using metabolic rate data. LoLinR provides methods to easily and reliably estimate monotonic rates from time series data in a way that is statistically robust, facilitates reproducible research and is applicable to a wide variety of research disciplines in the biological sciences. © 2017. Published by The Company of Biologists Ltd.

  16. Decay of density waves in coupled one-dimensional many-body-localized systems

    Science.gov (United States)

    Prelovšek, Peter

    2016-10-01

    This work analyzes the behavior of coupled disordered one-dimensional systems as modelled by identical fermionic Hubbard chains with the on-site potential disorder and coupling emerging through the interchain hopping t'. The study is motivated by the experiment on fermionic cold atoms on a disordered lattice, where a decay rate of the quenched density wave was measured. We present a derivation of the decay rate Γ within perturbation theory and show that, even at large disorder along the chains, the interaction leads to finite Γ >0 , the mechanism being the interaction-induced coupling of in-chain localized and interchain extended single-fermion states. Explicit expressions for Γ are presented for a weak interaction U U >t' . It is shown that, in both regimes, Γ increases with the interchain hopping t', as well as decreases with increasing disorder.

  17. On column density thresholds and the star formation rate

    CERN Document Server

    Clark, Paul C

    2013-01-01

    We present the results of a numerical study designed to address the question of whether there is a column density threshold for star formation within molecular clouds. We have simulated a large number of different clouds, with volume and column densities spanning a wide range of different values, using a state-of-the-art model for the coupled chemical, thermal and dynamical evolution of the gas. We show that for low-mass clouds, around 1000 solar masses and below, star formation is only possible if the mean cloud column density exceeds 10^21 cm^-2. In more massive clouds, the required mean column density is a factor of a few lower. We demonstrate that this behaviour is well-described by a simple Jeans mass argument: clouds must contain multiple Jeans masses in order to form stars, and hence star-forming clouds cannot have arbitrarily low column densities. We have also examined the question of whether there is a column density threshold for the regions within clouds where star formation occurs. We show that th...

  18. Advancing Fog Effect on VRML and X3D Using Local Fog Density

    Institute of Scientific and Technical Information of China (English)

    Seongah Chin

    2004-01-01

    In this paper an improved fog effect algorithm in VRML and X3 D is presented with respect to expressing density. The fundamental idea in the approach is to adapt local fog density having influence on Iocal regions with various grades of fog density whereas existing VRML and X3 D only make use of global fog effect. Several filters for making different fog density are presented along with experiments showing the correctness of the proposed method.

  19. Influence of Electrolyte Modulus on the Local Current Density at a Dendrite Tip on a Lithium Metal Electrode

    Energy Technology Data Exchange (ETDEWEB)

    Harry, KJ; Higa, K; Srinivasan, V; Balsara, NP

    2016-08-10

    Understanding and controlling the electrochemical deposition of lithium is imperative for the safe use of rechargeable batteries with a lithium metal anode. Solid block copolymer electrolyte membranes are known to enhance the stability of lithium metal anodes by mechanically suppressing the formation of lithium protrusions during battery charging. Time-resolved hard X-ray microtomography was used to monitor the internal structure of a symmetric lithium-polymer cell during galvanostatic polarization. The microtomography images were used to determine the local rate of lithium deposition, i.e. local current density, in the vicinity of a lithium globule growing through the electrolyte. Measurements of electrolyte displacement enabled estimation of local stresses in the electrolyte. At early times, the current density was maximized at the globule tip, as expected from simple current distribution arguments. At later times, the current density was maximized at the globule perimeter. We show that this phenomenon is related to the local stress fields that arise as the electrolyte is deformed. The local current density, normalized for the radius of curvature, decreases with increasing compressive stresses at the lithium-polymer interface. To our knowledge, our study provides the first direct measurement showing the influence of local mechanical stresses on the deposition kinetics at lithium metal electrodes.

  20. The evolution of foraging rate across local and geographic gradients in predation risk and competition.

    Science.gov (United States)

    Urban, Mark C; Richardson, Jonathan L

    2015-07-01

    Multiple theories predict the evolution of foraging rates in response to environmental variation in predation risk, intraspecific competition, time constraints, and temperature. We tested six hypotheses for the evolution of foraging rate in 24 spotted salamander (Ambystoma maculatum) populations from three latitudinally divergent sites using structural equation models derived from theory and applied to our system. We raised salamander larvae in a common-garden experiment and then assayed foraging rate under controlled conditions. Gape-limited predation risk from marbled salamanders solely explained foraging rate variation among populations at the southern site, which was dominated by this form of selection. However, at the middle and northern sites, populations evolved different foraging rates depending on their unique responses to local intraspecific density. The coupling of gape-limited predation risk from marbled salamanders and high intraspecific density at the middle site jointly contributed to selection for rapid foraging rate. At the northernmost site, intraspecific density alone explained 97% of the interpopulation variation in foraging rate. These results suggest that foraging rate has evolved multiple times in response to varying contributions from predation risk and intraspecific competition. Predation risk often varies along environmental gradients, and, thus, organisms might often shift evolutionary responses from minimizing predation risk to maximizing intraspecific competitive performance.

  1. Local densities connect spatial ecology to game, multilevel selection and inclusive fitness theories of cooperation.

    Science.gov (United States)

    Tekwa, Edward W; Gonzalez, Andrew; Loreau, Michel

    2015-09-07

    Cooperation plays a crucial role in many aspects of biology. We use the spatial ecological metrics of local densities to measure and model cooperative interactions. While local densities can be found as technical details in current theories, we aim to establish them as central to an approach that describes spatial effects in the evolution of cooperation. A resulting local interaction model neatly partitions various spatial and non-spatial selection mechanisms. Furthermore, local densities are shown to be fundamental for important metrics of game theory, multilevel selection theory and inclusive fitness theory. The corresponding metrics include structure coefficients, spatial variance, contextual covariance, relatedness, and inbreeding coefficient or F-statistics. Local densities serve as the basis of an emergent spatial theory that draws from and brings unity to multiple theories of cooperation.

  2. The local dayside reconnection rate for oblique interplanetary magnetic fields

    CERN Document Server

    Komar, Colin M

    2016-01-01

    We present an analysis of local properties of magnetic reconnection at the dayside magnetopause for various interplanetary magnetic field (IMF) orientations in global magnetospheric simulations. This has heretofore not been practical because it is difficult to locate where reconnection occurs for oblique IMF, but new techniques make this possible. The approach is to identify magnetic separators, the curves separating four regions of differing magnetic topology, which map the reconnection X-line. The electric field parallel to the X-line is the local reconnection rate. We compare results to a simple model of local two-dimensional asymmetric reconnection. To do so, we find the plasma parameters that locally drive reconnection in the magnetosheath and magnetosphere in planes perpendicular to the X-line at a large number of points along the X-line. The global magnetohydrodynamic simulations are from the three-dimensional Block-Adaptive, Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) code with a uniform resisti...

  3. Local specific absorption rate in brain tumors at 7 tesla.

    Science.gov (United States)

    Restivo, Matthew C; van den Berg, Cornelis A T; van Lier, Astrid L H M W; Polders, Daniël L; Raaijmakers, Alexander J E; Luijten, Peter R; Hoogduin, Hans

    2016-01-01

    MR safety at 7 Tesla relies on accurate numerical simulations of transmit electromagnetic fields to fully assess local specific absorption rate (SAR) safety. Numerical simulations for SAR safety are currently performed using models of healthy patients. These simulations might not be useful for estimating SAR in patients who have large lesions with potentially abnormal dielectric properties, e.g., brain tumors. In this study, brain tumor patient models are constructed based on scans of four patients with high grade brain tumors. Dielectric properties for the modeled tumors are assigned based on electrical properties tomography data for the same patients. Simulations were performed to determine SAR. Local SAR increases in the tumors by as much as 30%. However, the location of the maximum 10-gram averaged SAR typically occurs outside of the tumor, and thus does not increase. In the worst case, if the tumor model is moved to the location of maximum electric field intensity, then we do observe an increase in the estimated peak 10-gram SAR directly related to the tumor. Peak local SAR estimation made on the results of a healthy patient model simulation may underestimate the true peak local SAR in a brain tumor patient. © 2015 Wiley Periodicals, Inc.

  4. Adaptive partitioning by local density-peaks: An efficient density-based clustering algorithm for analyzing molecular dynamics trajectories.

    Science.gov (United States)

    Liu, Song; Zhu, Lizhe; Sheong, Fu Kit; Wang, Wei; Huang, Xuhui

    2017-01-30

    We present an efficient density-based adaptive-resolution clustering method APLoD for analyzing large-scale molecular dynamics (MD) trajectories. APLoD performs the k-nearest-neighbors search to estimate the density of MD conformations in a local fashion, which can group MD conformations in the same high-density region into a cluster. APLoD greatly improves the popular density peaks algorithm by reducing the running time and the memory usage by 2-3 orders of magnitude for systems ranging from alanine dipeptide to a 370-residue Maltose-binding protein. In addition, we demonstrate that APLoD can produce clusters with various sizes that are adaptive to the underlying density (i.e., larger clusters at low-density regions, while smaller clusters at high-density regions), which is a clear advantage over other popular clustering algorithms including k-centers and k-medoids. We anticipate that APLoD can be widely applied to split ultra-large MD datasets containing millions of conformations for subsequent construction of Markov State Models. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  5. Baroclinic pressure gradient difference schemes of subtracting the local averaged density stratification in sigma coordinates models

    Institute of Scientific and Technical Information of China (English)

    ZHU Shouxian; ZHANG Wenjing

    2008-01-01

    Much has been written of the error in computing the baroclinic pressure gradient (BPG) with sigma coordinates in ocean or atmos- pheric numerical models. The usual way to reduce the error is to subtract area-averaged density stratification of the whole computa- tion region. But if there is great difference between the area-averaged and the local averaged density stratification, the error will be obvious. An example is given to show that the error from this method may be larger than that from no correction sometimes. The definition of local area is put forward. Then, four improved BPG difference schemes of subtracting the local averaged density strat- ification are designed to reduce the error. Two of them are for diagnostic calculation (density field is fixed), and the others are for prognostic calculation (density field is not fixed). The results show that the errors from these schemes all significantly decrease.

  6. High-density localization of active molecules using Structured Sparse Model and Bayesian Information Criterion.

    Science.gov (United States)

    Quan, Tingwei; Zhu, Hongyu; Liu, Xiaomao; Liu, Yongfeng; Ding, Jiuping; Zeng, Shaoqun; Huang, Zhen-Li

    2011-08-29

    Localization-based super-resolution microscopy (or called localization microscopy) rely on repeated imaging and localization of active molecules, and the spatial resolution enhancement of localization microscopy is built upon the sacrifice of its temporal resolution. Developing algorithms for high-density localization of active molecules is a promising approach to increase the speed of localization microscopy. Here we present a new algorithm called SSM_BIC for such purpose. The SSM_BIC combines the advantages of the Structured Sparse Model (SSM) and the Bayesian Information Criterion (BIC). Through simulation and experimental studies, we evaluate systematically the performance between the SSM_BIC and the conventional Sparse algorithm in high-density localization of active molecules. We show that the SSM_BIC is superior in processing single molecule images with weak signal embedded in strong background.

  7. Generation of localized magnetic moments in the charge-density-wave state

    OpenAIRE

    Akzyanov, R. S.; Rozhkov, A. V.

    2014-01-01

    We propose a mechanism explaining the generation of localized magnetic moments in charge-density-wave compounds. Our model Hamiltonian describes an Anderson impurity placed in a host material exhibiting the charge-density wave. There is a region of the model's parameter space, where even weak Coulomb repulsion on the impurity site is able to localize the magnetic moment on the impurity. The phase diagram of a single impurity at T=0 is mapped. To establish the connection with experiment thermo...

  8. Direct mapping of local redox current density on a monolith electrode by laser scanning.

    Science.gov (United States)

    Lee, Seung-Woo; Lopez, Jeffrey; Saraf, Ravi F

    2013-09-15

    An optical method of mapping local redox reaction over a monolith electrode using simple laser scanning is described. As the optical signal is linearly proportional to the maximum redox current that is measured concomitantly by voltammetry, the optical signal quantitatively maps the local redox current density distribution. The method is demonstrated on two types of reactions: (1) a reversible reaction where the redox moieties are ionic, and (2) an irreversible reaction on two different types of enzymes immobilized on the electrode where the reaction moieties are nonionic. To demonstrate the scanning capability, the local redox behavior on a "V-shaped" electrode is studied where the local length scale and, hence, the local current density, is nonuniform. The ability to measure the current density distribution by this method will pave the way for multianalyte analysis on a monolith electrode using a standard three-electrode configuration. The method is called Scanning Electrometer for Electrical Double-layer (SEED).

  9. Local virial theorems and closed-orbit theory for spatial density oscillations in fermionic systems

    CERN Document Server

    Roccia, J; Koch, A; Murthy, M V N

    2009-01-01

    We investigate the particle and kinetic energy densities for a system of $N$ fermions confined in a local mean-field potential $V({\\bf r})$. For spherical harmonic oscillators in arbitrary dimensions, exact linear relations between kinetic and potential energy density, termed "local virial theorems", and some exact (integro-) differential equations for the particle density have been earlier derived. Here we use a recently developed semiclassical theory for density oscillations [J. Roccia and M. Brack, Phys. Rev. Lett. {\\bf 100}, 200408 (2008)] to generalize these theorems to arbitrary potentials and test their validity for various anharmonic potentials. We also discuss the relevance of our results for density functional theory. We show, in particular, that the Thomas-Fermi functional for a suitably defined kinetic energy density reproduces the quantum shell oscillations correctly to leading order in the oscillating parts.

  10. Enhanced HTS hit selection via a local hit rate analysis.

    Science.gov (United States)

    Posner, Bruce A; Xi, Hualin; Mills, James E J

    2009-10-01

    The postprocessing of high-throughput screening (HTS) results is complicated by the occurrence of false positives (inactive compounds misidentified as active by the primary screen) and false negatives (active compounds misidentified as inactive by the primary screen). An activity cutoff is frequently used to select "active" compounds from HTS data; however, this approach is insensitive to both false positives and false negatives. An alternative method that can minimize the occurrence of these artifacts will increase the efficiency of hit selection and therefore lead discovery. In this work, rather than merely using the activity of a given compound, we look at the presence and absence of activity among all compounds in its "chemical space neighborhood" to give a degree of confidence in its activity. We demonstrate that this local hit rate (LHR) analysis method outperforms hit selection based on ranking by primary screen activity values across ten diverse high throughput screens, spanning both cell-based and biochemical assay formats of varying biology and robustness. On average, the local hit rate analysis method was approximately 2.3-fold and approximately 1.3-fold more effective in identifying active compounds and active chemical series, respectively, than selection based on primary activity alone. Moreover, when applied to finding false negatives, this method was 2.3-fold better than ranking by primary activity alone. In most cases, novel hit series were identified that would have otherwise been missed. Additional uses of and observations regarding this HTS analysis approach are also discussed.

  11. Forecasting Exchange Rate Density Using Parametric Models: the Case of Brazil

    Directory of Open Access Journals (Sweden)

    Benjamin Miranda Tabak

    2007-06-01

    Full Text Available This paper employs a recently developed parametric technique to obtain density forecasts for the Brazilian exchange rate, using the exchange rate options market. Empirical results suggest that the option market contains useful information about future exchange rate density. These results suggests that density forecasts using options markets may add value for portfolio and risk management, and may be useful for financial regulators to assess financial stability.

  12. Local density of optical states of an asymmetric waveguide grating at photonic band gap resonant wavelength

    Science.gov (United States)

    Alatas, Husin; Sumaryada, Tony I.; Ahmad, Faozan

    2015-01-01

    We have investigated the characteristics of local density of optical states (LDOS) at photonic band gap resonant wavelength of an asymmetric waveguide grating based on Green's function formulation. It is found that the LDOS of the considered structure exhibits different characteristics in its localization between the upper and lower resonant wavelengths of the corresponding photonic band gap edges.

  13. Metal-insulator transition and local moment formation: A spin-density functional approach

    Science.gov (United States)

    Ghazali, A.; Leroux-Hugon, P.

    1980-01-01

    A more thorough description of the metal-insulator transition in correlated systems including local moment formation may be achieved through the spin-density functional method when compared to the Hubbard model. We have applied this method to doped semiconductors and found a transition between an insulating phase with local moments and a metallic one without moments.

  14. Non-Local Density Functional Description of Poly-Para-Phenylene Vinylene

    Institute of Scientific and Technical Information of China (English)

    ZHENG Guang; Clark S. J.; Brand S.; Abram R. A.

    2007-01-01

    A fully non-local exchange-correlation formalism within the framework of density functional theory, known as the weighted density approximation (WDA), has been applied to the conjugated polymer poly-para-phenylene vinylene (PPV) and is shown to lead to a marked improvement in the agreement of theory and experiment for the electronic band structure of the conjugated polymer. In particular, some new model WDA functions are developed, which substantially increase the electronic band gap of the polymer relative to those obtained with the local density approximation and generalized gradient approximation. The calculated band gap of PPV is quantitatively or at 1east semiquantitatively in agreement with the experimental data.

  15. Density of wild prey modulates lynx kill rates on free-ranging domestic sheep.

    Directory of Open Access Journals (Sweden)

    John Odden

    Full Text Available Understanding the factors shaping the dynamics of carnivore-livestock conflicts is vital to facilitate large carnivore conservation in multi-use landscapes. We investigated how the density of their main wild prey, roe deer Capreolus capreolus, modulates individual Eurasian lynx Lynx lynx kill rates on free-ranging domestic sheep Ovis aries across a range of sheep and roe deer densities. Lynx kill rates on free-ranging domestic sheep were collected in south-eastern Norway from 1995 to 2011 along a gradient of different livestock and wild prey densities using VHF and GPS telemetry. We used zero-inflated negative binomial (ZINB models including lynx sex, sheep density and an index of roe deer density as explanatory variables to model observed kill rates on sheep, and ranked the models based on their AICc values. The model including the effects of lynx sex and sheep density in the zero-inflation model and the effect of lynx sex and roe deer density in the negative binomial part received most support. Irrespective of sheep density and sex, we found the lowest sheep kill rates in areas with high densities of roe deer. As roe deer density decreased, males killed sheep at higher rates, and this pattern held for both high and low sheep densities. Similarly, females killed sheep at higher rates in areas with high densities of sheep and low densities of roe deer. However, when sheep densities were low females rarely killed sheep irrespective of roe deer density. Our quantification of depredation rates can be the first step towards establishing fairer compensation systems based on more accurate and area specific estimation of losses. This study demonstrates how we can use ecological theory to predict where losses of sheep will be greatest, and can be used to identify areas where mitigation measures are most likely to be needed.

  16. Local density regulates migratory songbird reproductive success through effects on double-brooding and nest predation.

    Science.gov (United States)

    Woodworth, Bradley K; Wheelwright, Nathaniel T; Newman, Amy E M; Norris, D Ryan

    2017-08-01

    Knowledge of the density-dependent processes that regulate animal populations is key to understanding, predicting, and conserving populations. In migratory birds, density-dependence is most often studied during the breeding season, yet we still lack a robust understanding of the reproductive traits through which density influences individual reproductive success. We used 27-yr of detailed, individual-level productivity data from an island-breeding population of Savannah sparrows Passerculus sandwichensis to evaluate effects of local and total annual population density on female reproductive success. Local density (number of neighbors within 50 m of a female's nest) had stronger effects on the number of young fledged than did total annual population density. Females nesting in areas of high local density were more likely to suffer nest predation and less likely to initiate and fledge a second clutch, which led to fewer young fledged in a season. Fledging fewer young subsequently decreased the likelihood of a female recruiting offspring into the breeding population in a subsequent year. Collectively, these results provide insight into the scale and reproductive mechanisms mediating density-dependent reproductive success and fitness in songbirds. © 2017 by the Ecological Society of America.

  17. Modulating toroidal flow stabilization of edge localized modes with plasma density

    CERN Document Server

    Cheng, Shikui; Banerjee, Debabrata

    2016-01-01

    Recent EAST experiments have demonstrated mitigation and suppression of edge localized modes (ELMs) with toroidal rotation flow in higher collisionality regime, suggesting potential roles of plasma density. In this work, the effects of plasma density on the toroidal flow stabilization of the high-$n$ edge localized modes have been extensively studied in linear calculations for a circular-shaped limiter H-mode tokamak, using the extended MHD code NIMROD. In the single MHD model, toroidal flow has a weak stabilizing effects on the high-$n$ modes. Such a stabilization, however, can be significantly enhanced with the increase in plasma density. Furthermore, our calculations show that the enhanced stabilization of high-$n$ modes from toroidal flow with higher edge plasma density persists in the 2-fluid MHD model. These findings may explain the ELM mitigation and suppression by toroidal rotation in higher collisionality regime due to the enhancement of plasma density obtained in recent EAST experiments.

  18. Exchange Flow Rate Measurement Technique in Density Different Gases

    Directory of Open Access Journals (Sweden)

    Motoo Fumizawa

    2012-04-01

    Full Text Available Buoyancy-driven exchange flows of helium-air through inclined a narrow tube was investigated. Exchange flows may occur following the opening of a window for ventilation, as well as when a pipe ruptures in a high temperature gas-cooled reactor. The experiment in this paper was carried out in a test chamber filled with helium and the flow was visualized using the smoke wire method. A high-speed camera recorded the flow behavior. The image of the flow was transferred to digital data, and the slow flow velocity, i.e. micro flow rate was measured by PIV software. Numerical simulation was carried out by the code of moving particle method with Lagrange method.

  19. Local and linear chemical reactivity response functions at finite temperature in density functional theory.

    Science.gov (United States)

    Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

    2015-12-28

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.

  20. Local and linear chemical reactivity response functions at finite temperature in density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Franco-Pérez, Marco, E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México, D.F. 09340 (Mexico); Ayers, Paul W., E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Gázquez, José L., E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México, D.F. 09340 (Mexico); Vela, Alberto, E-mail: francopj@mcmaster.ca, E-mail: ayers@mcmaster.ca, E-mail: jlgm@xanum.uam.mx, E-mail: avela@cinvestav.mx [Departamento de Química, Centro de Investigación y de Estudios Avanzados (Cinvestav), Av. Instituto Politécnico Nacional 2508, México, D.F. 07360 (Mexico)

    2015-12-28

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.

  1. Relationship of Remote Sensing Normalized Differential Vegetation Index to Anopheles Density and Malaria Incidence Rate

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    To study the relationship of remote sensing normalized differential vegetation index (NDVI) to Anopheles density and malaria incidence rate. Methods Data of monthly average climate, environment, Anopheles density and malaria incidence rate, and remote sensing NDVI were collected from 27 townships of 10 counties in southeastern Yunnan Province from 1984 to 1993. The relationship of remote sensing ecological proxy index, NDVI, to Anopheles density and malaria incidence rate was studied by principal component analysis, factor analysis and grey correlation analysis. Results The correlation matrix showed that NDVI highly correlated with Anopheles density in 4 townships of Mengla, Jinghong, and Yuanjiang counties, but in other 23 townships the relationship was not clear. Principal component and factor analyses showed that remote sensing NDVI was the representative index of the first principal component and the first common factor of Anopheles density evaluation. Grey correlation analysis showed that in rainy season NDVI had a high grey correlation with Anopheles density and malaria incidence rate. The grey correlation analysis showed that in rainy season the grey degree of NDVI correlated with Anopheles. Minimus density was 0.730, and 0.713 with Anopheles sinensis density, and 0.800 with malarial incidence rate. Conclusion Remote sensing NDVI can serve as a sensitive evaluation index of Anopheles density and malaria incidence rate.

  2. Combined effects of patch size and plant nutritional quality on local densities of insect herbivores

    NARCIS (Netherlands)

    Bukovinszky, T.; Gols, R.; Kamp, A.; Oliveira-Domingues, de F.; Hamback, P.A.; Jongema, Y.; Bezemer, T.M.; Dicke, M.; Dam, N.; Harvey, J.A.

    2010-01-01

    Plant–insect interactions occur in spatially heterogeneous habitats. Understanding how such interactions shape density distributions of herbivores requires knowledge on how variation in plant traits (e.g. nutritional quality) affects herbivore abundance through, for example, affecting movement rates

  3. Decay dynamics of quantum dots influenced by the local density of optical states of two-dimensional photonic crystal membranes

    DEFF Research Database (Denmark)

    Julsgaard, Brian; Johansen, Jeppe; Stobbe, Søren

    2008-01-01

    We have performed time-resolved spectroscopy on InAs quantum dot ensembles in photonic crystal membranes. The influence of the photonic crystal is investigated by varying the lattice constant systematically. We observe a strong slow down of the quantum dots’ spontaneous emission rates as the two-...... the bandgap in good agreement with local density of states calculations.......We have performed time-resolved spectroscopy on InAs quantum dot ensembles in photonic crystal membranes. The influence of the photonic crystal is investigated by varying the lattice constant systematically. We observe a strong slow down of the quantum dots’ spontaneous emission rates as the two...

  4. An evaluation of density-dependent and density-independent influences on population growth rates in Weddell seals

    Science.gov (United States)

    Rotella, J.J.; Link, W.A.; Nichols, J.D.; Hadley, G.L.; Garrott, R.A.; Proffitt, K.M.

    2009-01-01

    Much of the existing literature that evaluates the roles of density-dependent and density-independent factors on population dynamics has been called into question in recent years because measurement errors were not properly dealt with in analyses. Using state-space models to account for measurement errors, we evaluated a set of competing models for a 22-year time series of mark-resight estimates of abundance for a breeding population of female Weddell seals (Leptonychotes weddellii) studied in Erebus Bay, Antarctica. We tested for evidence of direct density dependence in growth rates and evaluated whether equilibrium population size was related to seasonal sea-ice extent and the Southern Oscillation Index (SOI). We found strong evidence of negative density dependence in annual growth rates for a population whose estimated size ranged from 438 to 623 females during the study. Based on Bayes factors, a density-dependence-only model was favored over models that also included en! vironmental covariates. According to the favored model, the population had a stationary distribution with a mean of 497 females (SD = 60.5), an expected growth rate of 1.10 (95% credible interval 1.08-1.15) when population size was 441 females, and a rate of 0.90 (95% credible interval 0.87-0.93) for a population of 553 females. A model including effects of SOI did receive some support and indicated a positive relationship between SOI and population size. However, effects of SOI were not large, and including the effect did not greatly reduce our estimate of process variation. We speculate that direct density dependence occurred because rates of adult survival, breeding, and temporary emigration were affected by limitations on per capita food resources and space for parturition and pup-rearing. To improve understanding of the relative roles of various demographic components and their associated vital rates to population growth rate, mark-recapture methods can be applied that incorporate both

  5. Effects of Electron Screening on Electron Capture Rates in High Density Presupernova Core

    Institute of Scientific and Technical Information of China (English)

    蒋广飞; 彭秋和; 邹志刚

    2003-01-01

    Considering that the electron capture rate can be greatly reduced by the electron screening effect in the regime of high temperature and high density, we calculate the effect of electron screening on the electron capture rate for two important elements 56Ni and 55Co in the high density condition of a pre-supernova star. The effect of electron screening is so effective that the electron capture rate may be reduced to about 20%.

  6. Distribution of local density of states in superstatistical random matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Abul-Magd, A.Y. [Department of Mathematics, Faculty of Science, Zagazig University, Zagazig (Egypt)]. E-mail: a_y_abul_magd@hotmail.com

    2007-07-02

    We expose an interesting connection between the distribution of local spectral density of states arising in the theory of disordered systems and the notion of superstatistics introduced by Beck and Cohen and recently incorporated in random matrix theory. The latter represents the matrix-element joint probability density function as an average of the corresponding quantity in the standard random-matrix theory over a distribution of level densities. We show that this distribution is in reasonable agreement with the numerical calculation for a disordered wire, which suggests to use the results of theory of disordered conductors in estimating the parameter distribution of the superstatistical random-matrix ensemble.

  7. Controlling the local false discovery rate in the adaptive Lasso

    KAUST Repository

    Sampson, J. N.

    2013-04-09

    The Lasso shrinkage procedure achieved its popularity, in part, by its tendency to shrink estimated coefficients to zero, and its ability to serve as a variable selection procedure. Using data-adaptive weights, the adaptive Lasso modified the original procedure to increase the penalty terms for those variables estimated to be less important by ordinary least squares. Although this modified procedure attained the oracle properties, the resulting models tend to include a large number of "false positives" in practice. Here, we adapt the concept of local false discovery rates (lFDRs) so that it applies to the sequence, λn, of smoothing parameters for the adaptive Lasso. We define the lFDR for a given λn to be the probability that the variable added to the model by decreasing λn to λn-δ is not associated with the outcome, where δ is a small value. We derive the relationship between the lFDR and λn, show lFDR =1 for traditional smoothing parameters, and show how to select λn so as to achieve a desired lFDR. We compare the smoothing parameters chosen to achieve a specified lFDR and those chosen to achieve the oracle properties, as well as their resulting estimates for model coefficients, with both simulation and an example from a genetic study of prostate specific antigen.

  8. UV Star Formation Rates in the Local Universe

    CERN Document Server

    Salim, Samir; Charlot, Stéphane; Brinchmann, Jarle; Johnson, Benjamin D; Schiminovich, David; Seibert, Mark; Mallery, Ryan; Heckman, Timothy M; Forster, Karl; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick; Neff, Susan G; Small, Todd; Wyder, Ted K; Bianchi, Luciana; Donas, Jose; Lee, Young-Wook; Madore, Barry F; Milliard, Bruno; Szalay, Alexander S; Welsh, Barry Y; Yi, Sukyoung K

    2007-01-01

    We measure star formation rates of ~50,000 optically-selected galaxies in the local universe (z~0.1), spanning a range from gas-rich dwarfs to massive ellipticals. We obtain dust-corrected SFRs by fitting the GALEX (UV) and SDSS (optical) photometry to a library of population synthesis models that include dust attenuation. For star-forming galaxies, our UV-based SFRs compare remarkably well with those derived from SDSS H alpha. Deviations from perfect agreement between these two methods are due to differences in the dust attenuation estimates. In contrast to H alpha, UV provides reliable SFRs for galaxies with weak or no H alpha emission, and where H alpha is contaminated with an emission from an AGN. We use full-SED SFRs to calibrate a simple prescription that uses GALEX UV magnitudes to produce good SFRs for normal star-forming galaxies. The specific SFR is considered as a function of stellar mass for (1) star-forming galaxies with no AGN, (2) those hosting an AGN, and for (3) galaxies without H alpha emiss...

  9. Communication: Near-locality of exchange and correlation density functionals for 1- and 2-electron systems

    Science.gov (United States)

    Sun, Jianwei; Perdew, John P.; Yang, Zenghui; Peng, Haowei

    2016-05-01

    The uniform electron gas and the hydrogen atom play fundamental roles in condensed matter physics and quantum chemistry. The former has an infinite number of electrons uniformly distributed over the neutralizing positively charged background, and the latter only one electron bound to the proton. The uniform electron gas was used to derive the local spin density approximation to the exchange-correlation functional that undergirds the development of the Kohn-Sham density functional theory. We show here that the ground-state exchange-correlation energies of the hydrogen atom and many other 1- and 2-electron systems are modeled surprisingly well by a different local spin density approximation (LSDA0). LSDA0 is constructed to satisfy exact constraints but agrees surprisingly well with the exact results for a uniform two-electron density in a finite, curved three-dimensional space. We also apply LSDA0 to excited or noded 1-electron densities, where it works less well. Furthermore, we show that the localization of the exact exchange hole for a 1- or 2-electron ground state can be measured by the ratio of the exact exchange energy to its optimal lower bound.

  10. Local offspring density and sex ratio affect sex allocation in the great tit

    NARCIS (Netherlands)

    Michler, Stephanie P. M.; Nicolaus, Marion; van der Velde, Marco; Radersma, Reinder; Ubels, Richard; Both, Christiaan; Komdeur, Jan; Tinbergen, Joost M.

    2013-01-01

    The expected fitness gain for offspring of a given sex may depend on local population sex ratio and density. Knowing the influence of such social factors on brood sex ratios may contribute considerably to the understanding of sex allocation in higher vertebrates. For 3 consecutive years, we

  11. Forster transfer and the local optical density of states in erbium-doped silica

    NARCIS (Netherlands)

    de Dood, MJA; Knoester, J; Tip, A; Polman, A

    2005-01-01

    dOptically excited erbium ions incorporated near the surface of a silica glass decay by spontaneous emission and-at high Er concentration-via Forster energy transfer to quenching sites. By externally modifying the photonic microstructure we vary the local optical density of states (LDOS) in samples

  12. Anisotropic behavior and inhomogeneity of atomic local densities of states in graphene with vacancy groups

    Directory of Open Access Journals (Sweden)

    V.V. Eremenko

    2016-06-01

    Full Text Available The electron local density of states (LDOS are calculated for graphene with isolated vacancies, divacancies and vacancy group of four nearest-neighbor vacancies. A strong anisotropy of behavior of LDOS near Fermi level is demonstrated for atoms near defect. Effect of next-to-nearest neighbor interaction on the properties of graphene with vacancies is established.

  13. Local offspring density and sex ratio affect sex allocation in the great tit

    NARCIS (Netherlands)

    Michler, Stephanie P. M.; Nicolaus, Marion; van der Velde, Marco; Radersma, Reinder; Ubels, Richard; Both, Christiaan; Komdeur, Jan; Tinbergen, Joost M.

    2013-01-01

    The expected fitness gain for offspring of a given sex may depend on local population sex ratio and density. Knowing the influence of such social factors on brood sex ratios may contribute considerably to the understanding of sex allocation in higher vertebrates. For 3 consecutive years, we manipula

  14. Do sex-specific densities affect local survival of free-ranging great tits?

    NARCIS (Netherlands)

    Michler, Stephanie P. M.; Nicolaus, Marion; Ubels, Richard; van der Velde, Marco; Both, Christiaan; Tinbergen, Joost M.; Komdeur, Jan

    2011-01-01

    Competition within sexes is expected when resources are sex specific, whereas competition between sexes can occur when similar resources are exploited. Local population density and sex ratio will determine the amount of sex-specific interactions and thus the potential degree of sex-specific

  15. Controlling fluorescent proteins by manipulating the local density of photonic states

    NARCIS (Netherlands)

    Blum, Christian; Cesa, Yanina; Broek, van den Johanna M.; Mosk, Allard P.; Subramaniam, Vinod; Vos, Willem L.; Campagnola, Paul J.; Stelzer, Ernst H.K.; Bally, von Gert

    2009-01-01

    We present the first demonstration of control of the emission lifetime of a biological emitter by manipulating the local density of optical states (LDOS). LDOS control is achieved by positioning the emitters at defined distances from a metallic mirror. This results in a characteristic oscillation in

  16. Electromagnetic local density of states in graphene-covered porous silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ting [Department of Physics, Nanchang University, Nanchang 330031 (China); Wang, Tong-Biao, E-mail: tbwang@ncu.edu.cn [Department of Physics, Nanchang University, Nanchang 330031 (China); Liao, Qing-Hua; Liu, Jiang-Tao; Yu, Tian-Bao [Department of Physics, Nanchang University, Nanchang 330031 (China); Liu, Nian-Hua [Institute for Advanced Study, Nanchang University, Nanchang 330031 (China)

    2017-06-21

    Surface phonon polariton supported by silicon carbide (SiC) can be strongly coupled with graphene plasmon in the graphene-covered SiC bulk. The spectrum of the electromagnetic local density of states exhibits two peaks whose positions can be tuned by the chemical potential of graphene. In this work, we study the electromagnetic local density of states in the proximity of a graphene-covered SiC with periodic hole arrays. The well-known peak from the coupling of surface polariton supported by SiC and graphene plasmon splits into two. With increased volume ratio of holes, one of the split peak shifts towards high frequencies, whereas the other moves towards low frequencies. The dependence of split-peak positions on the chemical potential and permittivity of filling materials in the holes are also investigated. This study offers another method of modulating the electromagnetic local density of states. - Highlights: • The electromagnetic local density of states in the proximity of graphene-covered anisotropic SiC is firstly studied. • The peak from resonance of surface phonon polaritons in the EM-LDOS spectrum can be split into two. • The split peaks can be tuned by chemical potential, filling factor, and filling materials. • Our results provide a new method to modulate the EM-LDOS.

  17. Mapping the Local Density of Optical States of a Photonic Crystal with Single Quantum Dots

    DEFF Research Database (Denmark)

    Wang, Qin; Stobbe, Søren; Lodahl, Peter

    2011-01-01

    We use single self-assembled InGaAs quantum dots as internal probes to map the local density of optical states of photonic crystal membranes. The employed technique separates contributions from nonradiative recombination and spin-flip processes by properly accounting for the role of the exciton...

  18. Definition of current density in the presence of a non-local potential.

    Science.gov (United States)

    Li, Changsheng; Wan, Langhui; Wei, Yadong; Wang, Jian

    2008-04-16

    In the presence of a non-local potential arising from electron-electron interaction, the conventional definition of current density J(c) = (e/2m)([(p-eA)ψ](*)ψ-ψ(*)[(p-eA)ψ]) cannot satisfy the condition of current conservation, i.e., [Formula: see text] in the steady state. In order to solve this problem, we give a new definition of current density including the contribution due to the non-local potential. We show that the current calculated based on the new definition of current density conserves the current and is the same as that obtained from the Landauer-Büttiker formula. Examples are given to demonstrate our results.

  19. Green's Dyadic, Spectral Function, Local Density of States, and Fluctuation Dissipation Theorem

    CERN Document Server

    Chew, W C; Dai, Q I

    2015-01-01

    The spectral functions are studied in conjunction with the dyadic Green's functions for various media. The dyadic Green's functions are found using the eigenfunction expansion method for homogeneous, inhomogeneous, periodic, lossless, lossy, and anisotropic media, guided by the Bloch- Floquet theorem. For the lossless media cases, the spectral functions can be directly related to the photon local density of states, and hence, to the electromagnetic energy density. For the lossy case, the spectral function can be related to the ?eld correlation function. Because of these properties, one can derive properties for ?eld correlations and the Langevin-source correlations without resorting to the uctuation dissipation theorem. The results are corroborated by the uctuation dissipation theorem. An expression for the local density of states for lossy, inhomogeneous, and dispersive media has also been suggested.

  20. Properties of Dark Matter Halos as a Function of Local Environment Density

    CERN Document Server

    Lee, Christoph T; Behroozi, Peter; Rodriguez-Puebla, Aldo; Hellinger, Doug; Dekel, Avishai

    2016-01-01

    We study how properties of discrete dark matter halos depend on halo environment, characterized by the mass density around the halos on scales from 0.5 to 16 $\\hmpc$. We find that low mass halos (those less massive than the characteristic mass $M_{\\rm C}$ of halos collapsing at a given epoch) in high-density environments have lower accretion rates, lower spins, higher concentrations, and rounder shapes than halos in median density environments. Halos in median and low-density environments have similar accretion rates and concentrations, but halos in low density environments have lower spins and are more elongated. Halos of a given mass in high-density regions accrete material earlier than halos of the same mass in lower-density regions. All but the most massive halos in high-density regions are losing mass (i.e., being stripped) at low redshifts, which causes artificially lowered NFW scale radii and increased concentrations. Tidal effects are also responsible for the decreasing spins of low mass halos in high...

  1. Coral reef degradation is not correlated with local human population density

    Science.gov (United States)

    Bruno, John F.; Valdivia, Abel

    2016-07-01

    The global decline of reef-building corals is understood to be due to a combination of local and global stressors. However, many reef scientists assume that local factors predominate and that isolated reefs, far from human activities, are generally healthier and more resilient. Here we show that coral reef degradation is not correlated with human population density. This suggests that local factors such as fishing and pollution are having minimal effects or that their impacts are masked by global drivers such as ocean warming. Our results also suggest that the effects of local and global stressors are antagonistic, rather than synergistic as widely assumed. These findings indicate that local management alone cannot restore coral populations or increase the resilience of reefs to large-scale impacts. They also highlight the truly global reach of anthropogenic warming and the immediate need for drastic and sustained cuts in carbon emissions.

  2. Local gene density predicts the spatial position of genetic loci in the interphase nucleus.

    Science.gov (United States)

    Murmann, Andrea E; Gao, Juntao; Encinosa, Marissa; Gautier, Mathieu; Peter, Marcus E; Eils, Roland; Lichter, Peter; Rowley, Janet D

    2005-11-15

    Specific chromosomal translocations are hallmarks of many human leukemias. The basis for these translocation events is poorly understood, but it has been assumed that spatial positioning of genes in the nucleus of hematopoietic cells is a contributing factor. Analysis of the nuclear 3D position of the gene MLL, frequently involved in chromosomal translocations and five of its translocation partners (AF4, AF6, AF9, ENL and ELL), and two control loci revealed a characteristic radial distribution pattern in all hematopoietic cells studied. Genes in areas of high local gene density were found positioned towards the nuclear center, whereas genes in regions of low gene density were detected closer to the nuclear periphery. The gene density within a 2 Mbp window was found to be a better predictor for the relative positioning of a genomic locus within the cell nucleus than the gene density of entire chromosomes. Analysis of the position of MLL, AF4, AF6 and AF9 in cell lines carrying chromosomal translocations involving these genes revealed that the position of the normal genes was different from that of the fusion genes, and this was again consistent with the changes in local gene density within a 2 Mbp window. Thus, alterations in gene density directly at translocation junctions could explain the change in the position of affected genes in leukemia cells.

  3. Alternative Measured-Service Rate Structures for Local Telephone Service,

    Science.gov (United States)

    1980-06-01

    Pricing," American Economic Review , Vol. 60, 1970, pp. 265-283. Cosgrove, J. G. and P. G. Linhart, "Customer Choices Under Local Measured Telephone...November 1976. "Optimal Pricing of Local Telephone Service," American Economic Review , Vol. 68, September 1978, pp. 517-537. , "Economic Issues in

  4. The scaling of contact rates with population density for the infectious disease models.

    Science.gov (United States)

    Hu, Hao; Nigmatulina, Karima; Eckhoff, Philip

    2013-08-01

    Contact rates and patterns among individuals in a geographic area drive transmission of directly-transmitted pathogens, making it essential to understand and estimate contacts for simulation of disease dynamics. Under the uniform mixing assumption, one of two mechanisms is typically used to describe the relation between contact rate and population density: density-dependent or frequency-dependent. Based on existing evidence of population threshold and human mobility patterns, we formulated a spatial contact model to describe the appropriate form of transmission with initial growth at low density and saturation at higher density. We show that the two mechanisms are extreme cases that do not capture real population movement across all scales. Empirical data of human and wildlife diseases indicate that a nonlinear function may work better when looking at the full spectrum of densities. This estimation can be applied to large areas with population mixing in general activities. For crowds with unusually large densities (e.g., transportation terminals, stadiums, or mass gatherings), the lack of organized social contact structure deviates the physical contacts towards a special case of the spatial contact model - the dynamics of kinetic gas molecule collision. In this case, an ideal gas model with van der Waals correction fits well; existing movement observation data and the contact rate between individuals is estimated using kinetic theory. A complete picture of contact rate scaling with population density may help clarify the definition of transmission rates in heterogeneous, large-scale spatial systems.

  5. Do galaxy global relationships emerge from local ones? The SDSS IV MaNGA surface mass density-metallicity relation

    CERN Document Server

    Barrera-Ballesteros, Jorge K; Zhu, Guangtun B; Zakamska, Nadia L; Sánchez, Sebastian F; Law, David; Wake, David; Green, Jenny E; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey; Malanushenko, Elena; Pan, Kaike; Lopes, Alexandre Roman; Lane, Richard R

    2016-01-01

    We present the stellar surface mass density {\\it vs.} gas metallicity ($\\Sigma_*-Z$) relation for more than 500,000 spatially-resolved star-forming resolution elements (spaxels) from a sample of 653 disk galaxies included in the SDSS IV MaNGA survey. We find a tight relation between these local properties, with higher metallicities as the surface density increases. This relation extends over three orders of magnitude in the surface mass density and a factor of four in metallicity. We show that this local relationship can simultaneously reproduce two well-known properties of disk galaxies: their global mass-metallicity relationship {\\it and} their radial metallicity gradients. We also find that the $\\Sigma_* - Z$ relation is largely independent of the galaxy's total stellar mass and specific star-formation rate (sSFR), except at low stellar mass and high sSFR. These results suggest that in the present-day universe local properties play a key role in determining the gas-phase metallicity in typical disk galaxie...

  6. Do galaxy global relationships emerge from local ones? The SDSS IV MaNGA surface mass density-metallicity relation

    Science.gov (United States)

    Barrera-Ballesteros, Jorge K.; Heckman, Timothy M.; Zhu, Guangtun B.; Zakamska, Nadia L.; Sánchez, Sebastian F.; Law, David; Wake, David; Green, Jenny E.; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey; Malanushenko, Elena; Pan, Kaike; Roman Lopes, Alexandre; Lane, Richard R.

    2016-12-01

    We present the stellar surface mass density versus gas metallicity (Σ*-Z) relation for more than 500 000 spatially resolved star-forming resolution elements (spaxels) from a sample of 653 disc galaxies included in the SDSS IV MaNGA survey. We find a tight relation between these local properties, with higher metallicities as the surface density increases. This relation extends over three orders of magnitude in the surface mass density and a factor of 4 in metallicity. We show that this local relationship can simultaneously reproduce two well-known properties of disc galaxies: their global mass-metallicity relationship and their radial metallicity gradients. We also find that the Σ*-Z relation is largely independent of the galaxy's total stellar mass and specific star formation rate (sSFR), except at low stellar mass and high sSFR. These results suggest that in the present-day universe local properties play a key role in determining the gas-phase metallicity in typical disc galaxies.

  7. Density and hazard rate estimation for censored and a-mixing data using gamma kernels

    OpenAIRE

    2006-01-01

    In this paper we consider the nonparametric estimation for a density and hazard rate function for right censored -mixing survival time data using kernel smoothing techniques. Since survival times are positive with potentially a high concentration at zero, one has to take into account the bias problems when the functions are estimated in the boundary region. In this paper, gamma kernel estimators of the density and the hazard rate function are proposed. The estimators use adaptive weights depe...

  8. Symmetry-broken local-density approximation for one-dimensional systems

    CERN Document Server

    Rogers, Fergus J M; Loos, Pierre-François

    2016-01-01

    Within density-functional theory, the local-density approximation (LDA) correlation functional is typically built by fitting the difference between the near-exact and Hartree-Fock (HF) energies of the uniform electron gas (UEG), together with analytic perturbative results from the high- and low-density regimes. Near-exact energies are obtained by performing accurate diffusion Monte Carlo calculations, while HF energies are usually assumed to be the Fermi fluid HF energy. However, it has been known since the seminal work of Overhauser that one can obtain lower, symmetry-broken (SB) HF energies at any density. Here, we have computed the SBHF energies of the one-dimensional UEG and constructed a SB version of the LDA (SBLDA) from the results. We compare the performance of the LDA and SBLDA functionals when applied to one-dimensional systems, including atoms and molecules. Generalization to higher dimensions is also discussed.

  9. Charged-Particle Thermonuclear Reaction Rates: II. Tables and Graphs of Reaction Rates and Probability Density Functions

    CERN Document Server

    Iliadis, Christian; Champagne, Art; Coc, Alain; Fitzgerald, Ryan

    2010-01-01

    Numerical values of charged-particle thermonuclear reaction rates for nuclei in the A=14 to 40 region are tabulated. The results are obtained using a method, based on Monte Carlo techniques, that has been described in the preceding paper of this series (Paper I). We present a low rate, median rate and high rate which correspond to the 0.16, 0.50 and 0.84 quantiles, respectively, of the cumulative reaction rate distribution. The meaning of these quantities is in general different from the commonly reported, but statistically meaningless expressions, "lower limit", "nominal value" and "upper limit" of the total reaction rate. In addition, we approximate the Monte Carlo probability density function of the total reaction rate by a lognormal distribution and tabulate the lognormal parameters {\\mu} and {\\sigma} at each temperature. We also provide a quantitative measure (Anderson-Darling test statistic) for the reliability of the lognormal approximation. The user can implement the approximate lognormal reaction rat...

  10. Relative Contribution of Matrix Structure, Patch Resources and Management to the Local Densities of Two Large Blue Butterfly Species.

    Science.gov (United States)

    Kajzer-Bonk, Joanna; Skórka, Piotr; Nowicki, Piotr; Bonk, Maciej; Król, Wiesław; Szpiłyk, Damian; Woyciechowski, Michal

    2016-01-01

    The type of matrix, the landscape surrounding habitat patches, may determine the distribution and function of local populations. However, the matrix is often heterogeneous, and its various components may differentially contribute to metapopulation processes at different spatial scales, a phenomenon that has rarely been investigated. The aim of this study was to estimate the relative importance of matrix composition and spatial scale, habitat quality, and management intensity on the occurrence and density of local populations of two endangered large blue butterflies: Phengaris teleius and P. nausithous. Presence and abundance data were assessed over two years, 2011-12, in 100 local patches within two heterogeneous regions (near Kraków and Tarnów, southern Poland). The matrix composition was analyzed at eight spatial scales. We observed high occupancy rates in both species, regions and years. With the exception of area and isolation, almost all of the matrix components contributed to Phengaris sp. densities. The different matrix components acted at different spatial scales (grassland cover within 4 and 3 km, field cover within 0.4 and 0.3 km and water cover within 4 km radii for P. teleius and P. nausithous, respectively) and provided the highest independent contribution to the butterfly densities. Additionally, the effects of a 0.4 km radius of forest cover and a food plant cover on P. teleius, and a 1 km radius of settlement cover and management intensity on P. nausithous densities were observed. Contrary to former studies we conclude that the matrix heterogeneity and spatial scale rather than general matrix type are of relevance for densities of butterflies. Conservation strategies for these umbrella species should concentrate on maintaining habitat quality and managing matrix composition at the most appropriate spatial scales.

  11. Density and localized states' impact on amorphous carbon electron transport mechanisms

    Science.gov (United States)

    Caicedo-Dávila, S.; Lopez-Acevedo, O.; Velasco-Medina, J.; Avila, A.

    2016-12-01

    This work discusses the electron transport mechanisms that we obtained as a function of the density of amorphous carbon (a-C) ultra-thin films. We calculated the density of states (total and projected), degree of electronic states' localization, and transmission function using the density functional theory and nonequilibrium Green's functions method. We generated 25 sample a-C structures using ab-initio molecular dynamics within the isothermal-isobaric ensemble. We identified three transport regimes as a function of the density, varying from semimetallic in low-density samples ( ≤2.4 g/cm3) to thermally activated in high-density ( ≥2.9 g/cm3) tetrahedral a-C. The middle-range densities (2.4 g/cm3 ≤ρ≤ 2.9 g/cm3) are characterized by resonant tunneling and hopping transport. Our findings offer a different perspective from the tight-binding model proposed by Katkov and Bhattacharyya [J. Appl. Phys. 113, 183712 (2013)], and agree with experimental observations in low-dimensional carbon systems [see S. Bhattacharyya, Appl. Phys. Lett. 91, 21 (2007)]. Identifying transport regimes is crucial to the process of understanding and applying a-C thin film in electronic devices and electrode coating in biosensors.

  12. Testing the impact of local alcohol licencing policies on reported crime rates in England

    Science.gov (United States)

    De Vocht, F; Heron, J; Campbell, R; Egan, M; Mooney, J D; Angus, C; Brennan, A; Hickman, M

    2017-01-01

    Background Excessive alcohol use contributes to public nuisance, antisocial behaviour, and domestic, interpersonal and sexual violence. We test whether licencing policies aimed at restricting its spatial and/or temporal availability, including cumulative impact zones, are associated with reductions in alcohol-related crime. Methods Reported crimes at English lower tier local authority (LTLA) level were used to calculate the rates of reported crimes including alcohol-attributable rates of sexual offences and violence against a person, and public order offences. Financial fraud was included as a control crime not directly associated with alcohol abuse. Each area was classified as to its cumulative licensing policy intensity for 2009–2015 and categorised as ‘passive’, low, medium or high. Crime rates adjusted for area deprivation, outlet density, alcohol-related hospital admissions and population size at baseline were analysed using hierarchical (log-rate) growth modelling. Results 284 of 326 LTLAs could be linked and had complete data. From 2009 to 2013 alcohol-related violent and sexual crimes and public order offences rates declined faster in areas with more ‘intense’ policies (about 1.2, 0.10 and 1.7 per 1000 people compared with 0.6, 0.01 and 1.0 per 1000 people in ‘passive’ areas, respectively). Post-2013, the recorded rates increased again. No trends were observed for financial fraud. Conclusions Local areas in England with more intense alcohol licensing policies had a stronger decline in rates of violent crimes, sexual crimes and public order offences in the period up to 2013 of the order of 4–6% greater compared with areas where these policies were not in place, but not thereafter. PMID:27514936

  13. Local activation time sampling density for atrial tachycardia contact mapping: how much is enough?

    Science.gov (United States)

    Williams, Steven E; Harrison, James L; Chubb, Henry; Whitaker, John; Kiedrowicz, Radek; Rinaldi, Christopher A; Cooklin, Michael; Wright, Matthew; Niederer, Steven; O'Neill, Mark D

    2017-04-03

    Local activation time (LAT) mapping forms the cornerstone of atrial tachycardia diagnosis. Although anatomic and positional accuracy of electroanatomic mapping (EAM) systems have been validated, the effect of electrode sampling density on LAT map reconstruction is not known. Here, we study the effect of chamber geometry and activation complexity on optimal LAT sampling density using a combined in silico and in vivo approach. In vivo 21 atrial tachycardia maps were studied in three groups: (1) focal activation, (2) macro-re-entry, and (3) localized re-entry. In silico activation was simulated on a 4×4cm atrial monolayer, sampled randomly at 0.25-10 points/cm2 and used to re-interpolate LAT maps. Activation patterns were studied in the geometrically simple porcine right atrium (RA) and complex human left atrium (LA). Activation complexity was introduced into the porcine RA by incomplete inter-caval linear ablation. In all cases, optimal sampling density was defined as the highest density resulting in minimal further error reduction in the re-interpolated maps. Optimal sampling densities for LA tachycardias were 0.67 ± 0.17 points/cm2 (focal activation), 1.05 ± 0.32 points/cm2 (macro-re-entry) and 1.23 ± 0.26 points/cm2 (localized re-entry), P = 0.0031. Increasing activation complexity was associated with increased optimal sampling density both in silico (focal activation 1.09 ± 0.14 points/cm2; re-entry 1.44 ± 0.49 points/cm2; spiral-wave 1.50 ± 0.34 points/cm2, P density (0.61 ± 0.22 points/cm2 vs. 1.0 ± 0.34 points/cm2, P = 0.0015). Optimal sampling densities can be identified to maximize diagnostic yield of LAT maps. Greater sampling density is required to correctly reveal complex activation and represent activation across complex geometries. Overall, the optimal sampling density for LAT map interpolation defined in this study was ∼1.0-1.5 points/cm2.

  14. Effect of the Heat Flux Density on the Evaporation Rate of a Distilled Water Drop

    Directory of Open Access Journals (Sweden)

    Ponomarev Konstantin

    2016-01-01

    Full Text Available This paper presents the experimental dependence of the evaporation rate of a nondeaerated distilled water drop from the heat flux density on the surfaces of non-ferrous metals (copper and brass. A drop was placed on a heated substrate by electronic dosing device. To obtain drop profile we use a shadow optical system; drop symmetry was controlled by a high-speed video camera. It was found that the evaporation rate of a drop on a copper substrate is greater than on a brass. The evaporation rate increases intensively with raising volume of a drop. Calculated values of the heat flux density and the corresponding evaporation rates are presented in this work. The evaporation rate is found to increase intensively on the brass substrate with raising the heat flux density.

  15. The effect of density gradient on the growth rate of relativistic Weibel instability

    Energy Technology Data Exchange (ETDEWEB)

    Mahdavi, M., E-mail: m.mahdavi@umz.ac.ir [Physics Department, University of Mazandaran, P.O. Box 47415-416, Babolsar (Iran, Islamic Republic of); Khodadadi Azadboni, F., E-mail: f.khodadadi@stu.umz.ac.ir [Physics Department, University of Mazandaran, P.O. Box 47415-416, Babolsar (Iran, Islamic Republic of); Young Researchers Club, Sari Branch, Islamic Azad University, P.O. Box 48161-194, Sari (Iran, Islamic Republic of)

    2014-02-15

    In this paper, the effect of density gradient on the Weibel instability growth rate is investigated. The density perturbations in the near corona fuel, where temperature anisotropy, η, is larger than the critical temperature anisotropy, η{sub c}, (η > η{sub c}), enhances the growth rate of Weibel instability due to the sidebands coupled with the electron oscillatory velocity. But for η < η{sub c}, the thermal spread of the energetic electrons reduces the growth rate. Also, the growth rate can be reduced if the relativistic parameter (Lorentz factor) is sufficiently large, γ > 2. The analysis shows that relativistic effects and density gradient tend to stabilize the Weibel instability. The growth rate can be reduced by 88% by reducing η by a factor of 100 and increasing relativistic parameter by a factor of 3.

  16. Bounds on the local energy density of holographic CFTs from bulk geometry

    CERN Document Server

    Fischetti, Sebastian; Wiseman, Toby

    2016-01-01

    The stress tensor is a basic local operator in any field theory; in the context of AdS/CFT, it is the operator which is dual to the bulk geometry itself. Here we exploit this feature by using the bulk geometry to place constraints on the local energy density in static states of holographic $(2+1)$-dimensional CFTs living on a closed (but otherwise generally curved) spatial geometry. We allow for the presence of a marginal scalar deformation, dual to a massless scalar field in the bulk. For certain vacuum states in which the bulk geometry is well-behaved at zero temperature, we find that the bulk equations of motion imply that the local energy density integrated over specific boundary domains is negative. In the absence of scalar deformations, we use the inverse mean curvature flow to show that if the CFT spatial geometry has spherical topology but non-constant curvature, the local energy density must be positive somewhere. This result extends to other topologies, but only for certain types of vacuum; in parti...

  17. Bounds on the local energy density of holographic CFTs from bulk geometry

    Science.gov (United States)

    Fischetti, Sebastian; Hickling, Andrew; Wiseman, Toby

    2016-11-01

    The stress tensor is a basic local operator in any field theory; in the context of AdS/CFT, it is the operator which is dual to the bulk geometry itself. Here we exploit this feature by using the bulk geometry to place constraints on the local energy density in static states of holographic (2+1)-dimensional CFTs living on a closed (but otherwise generally curved) spatial geometry. We allow for the presence of a marginal scalar deformation, dual to a massless scalar field in the bulk. For certain vacuum states in which the bulk geometry is well-behaved at zero temperature, we find that the bulk equations of motion imply that the local energy density integrated over specific boundary domains is negative. In the absence of scalar deformations, we use the inverse mean curvature flow to show that if the CFT spatial geometry has spherical topology but non-constant curvature, the local energy density must be positive somewhere. This result extends to other topologies, but only for certain types of vacuum; in particular, for a generic toroidal boundary, the vacuum’s bulk dual must be the zero-temperature limit of a toroidal black hole.

  18. Effect of Loading Densities in Closed Vessel Tests on the Burning Rate of a Propelling Charge

    Directory of Open Access Journals (Sweden)

    Pragati Mehta

    2015-04-01

    Full Text Available Closed vessel firing of gun propellant at different loading densities is conducted for evaluation of its ballistic parameters. Although in actual gun applications, loading densities are higher, but for closed vessel evaluation standard loading density is taken as 0.2 g/cc for interior ballistic calculations of guns. Closed vessel evaluation of standard triple-base propellant in hepta-tubular configuration with loading density varying in the range of 0.2 g/cc to 0.3 g/cc is conducted for the evaluation of salient ballistic parameters. It is observed that maximum pressure increases with increase in loading density of propellants. As loading density increases, rate of rise of pressure also increases. Accordingly, a rise in burning rate is also observed. However, the burning rate index (α and coefficient (β of the power law of burning (r = βPα is found independent of loading density. The average values of these burning rate parameters are calculated as (α = 0.78 and (β = 0.45 for the studied propellant.Defence Science Journal, Vol. 65, No. 2, March 2015, pp.126-130, DOI:http://dx.doi.org/10.14429/dsj.65.8158

  19. Increased upconversion quantum yield in photonic structures due to local field enhancement and modification of the local density of states--a simulation-based analysis.

    Science.gov (United States)

    Herter, Barbara; Wolf, Sebastian; Fischer, Stefan; Gutmann, Johannes; Bläsi, Benedikt; Goldschmidt, Jan Christoph

    2013-09-09

    In upconversion processes, two or more low-energy photons are converted into one higher-energy photon. Besides other applications, upconversion has the potential to decrease sub-band-gap losses in silicon solar cells. Unfortunately, upconverting materials known today show quantum yields, which are too low for this application. In order to improve the upconversion quantum yield, two parameters can be tuned using photonic structures: first, the irradiance can be increased within the structure. This is beneficial, as upconversion is a non-linear process. Second, the rates of the radiative transitions between ionic states within the upconverter material can be altered due to a varied local density of photonic states. In this paper, we present a theoretical model of the impact of a photonic structure on upconversion and test this model in a simulation based analysis of the upconverter material β -NaYF(4):20% Er(3+) within a dielectric waveguide structure. The simulation combines a finite-difference time-domain simulation model that describes the variations of the irradiance and the change of the local density of photonic states within a photonic structure, with a rate equation model of the upconversion processes. We find that averaged over the investigated structure the upconversion luminescence is increased by a factor of 3.3, and the upconversion quantum yield can be improved in average by a factor of 1.8 compared to the case without the structure for an initial irradiance of 200 Wm(-2).

  20. Impact of population density on collision rates in a rapidly developing rural, exurban area of Los Angeles County.

    Science.gov (United States)

    Fischer, Kelly; Sternfeld, Isabelle; Melnick, Douglas Sloan

    2013-04-01

    To determine if the commonly acknowledged relationships between population density and traffic collisions are found at the subcounty level and to describe how collision characteristics may vary substantially at a local level, with a particular emphasis on exurban areas. Los Angeles County collision data were obtained from the California Highway Patrol and the census tract and service planning area (SPA) for each collision were determined. The correlation between population density and collision rates by census tract was calculated within each SPA and for the entire county. Primary collision factors were compared for geographic areas of different population densities within one exurban SPA in Los Angeles County. An inverse relationship was found between collision rates and population density within Los Angeles County. Primary collisions factors were different in areas of the county with different population densities, with driving or biking under the influence particularly common in the most rural area. Subcounty analyses are very important to the study of traffic collisions. Traffic problems in rapidly developing exurban areas may be quite different from those in older, more established areas.

  1. Phototactic number-density flux in the localized bioconvection of Euglena gracilis

    Science.gov (United States)

    Shoji, Erika; Suematsu, Nobuhiko; Nishimori, Hiraku; Awazu, Akinori; Izumi, Shunsuke; Iima, Makoto

    2014-11-01

    Euglena gracilis is a unicellular phototactic flagellate; it escapes from light sources if the light intensity is higher than 200 W/m2 (negative phototaxis). When the suspension of E. gracilis is illuminated from the bottom by strong light, bioconvection patterns are generated. In the case of E. gracilis, the patterns can be spatially localized. The localization mechanism has not been clarified. We report experimental results related to the localization mechanism. In particular, we experimentally measured the strength of the phototaxis in the lateral direction as well as vertical direction. We prepared a thin container in which the suspension is included, and gave the linearly-changing light intensity. We found the number density gets a peak at a particular light intensity, which never happens if the suspension has the vertical phototaxis only. Further, we succeeded in getting the function representing lateral phototaxis. The relationship between the measured functions and the localized convection cells will be also reported.

  2. The local projection in the density functional theory plus U approach: A critical assessment.

    Science.gov (United States)

    Wang, Yue-Chao; Chen, Ze-Hua; Jiang, Hong

    2016-04-14

    Density-functional theory plus the Hubbard U correction (DFT + U) method is widely used in first-principles studies of strongly correlated systems, as it can give qualitatively (and sometimes, semi-quantitatively) correct description of energetic and structural properties of many strongly correlated systems with similar computational cost as local density approximation or generalized gradient approximation. On the other hand, the DFT + U approach is limited both theoretically and practically in several important aspects. In particular, the results of DFT + U often depend on the choice of local orbitals (the local projection) defining the subspace in which the Hubbard U correction is applied. In this work we have systematically investigated the issue of the local projection by considering typical transition metal oxides, β-MnO2 and MnO, and comparing the results obtained from different implementations of DFT + U. We found that the choice of the local projection has significant effects on the DFT + U results, which are more significant for systems with stronger covalent bonding (e.g., MnO2) than those with more ionic bonding (e.g., MnO). These findings can help to clarify some confusion arising from the practical use of DFT + U and may also provide insights for the development of new first-principles approaches beyond DFT + U.

  3. Exact density functional and wave function embedding schemes based on orbital localization

    Science.gov (United States)

    Hégely, Bence; Nagy, Péter R.; Ferenczy, György G.; Kállay, Mihály

    2016-08-01

    Exact schemes for the embedding of density functional theory (DFT) and wave function theory (WFT) methods into lower-level DFT or WFT approaches are introduced utilizing orbital localization. First, a simple modification of the projector-based embedding scheme of Manby and co-workers [J. Chem. Phys. 140, 18A507 (2014)] is proposed. We also use localized orbitals to partition the system, but instead of augmenting the Fock operator with a somewhat arbitrary level-shift projector we solve the Huzinaga-equation, which strictly enforces the Pauli exclusion principle. Second, the embedding of WFT methods in local correlation approaches is studied. Since the latter methods split up the system into local domains, very simple embedding theories can be defined if the domains of the active subsystem and the environment are treated at a different level. The considered embedding schemes are benchmarked for reaction energies and compared to quantum mechanics (QM)/molecular mechanics (MM) and vacuum embedding. We conclude that for DFT-in-DFT embedding, the Huzinaga-equation-based scheme is more efficient than the other approaches, but QM/MM or even simple vacuum embedding is still competitive in particular cases. Concerning the embedding of wave function methods, the clear winner is the embedding of WFT into low-level local correlation approaches, and WFT-in-DFT embedding can only be more advantageous if a non-hybrid density functional is employed.

  4. Density of states controls Anderson localization in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Garcia-Fernández, David; Smolka, Stephan; Stobbe, Søren

    2010-01-01

    -of-plane losses are non-negligible, ℓe can be approximated to be the localization length ξ. The extinction mean-free path shows a fivefold variation between the low- and the high-DOS regime, and it becomes shorter than the sample length thus giving rise to strongly confined modes. The dispersive behavior of ℓe......We prove Anderson localization in a disordered photonic crystal waveguide by measuring the ensemble-averaged extinction mean-free path, ℓe, which is controlled by the dispersion in the photon density of states (DOS) of the photonic crystal waveguide. Except for the very low DOS case, where out...

  5. Orbital localization, charge transfer, and band gaps in semilocal density-functional theory.

    Science.gov (United States)

    Armiento, R; Kümmel, S

    2013-07-19

    We derive an exchange energy functional of generalized gradient form with a corresponding potential that changes discontinuously at integer particle numbers. The functional is semilocal, yet incorporates key features that are connected to the derivative discontinuity of Kohn-Sham density-functional theory. We validate our construction for several paradigm systems and explain how it addresses central well-known deficiencies of antecedent semilocal methods, i.e., the description of charge transfer, properly localized orbitals, and band gaps. We find, e.g., an improved shell structure for atoms, eigenvalues that more closely correspond to ionization energies, and an improved description of band structure where localized states are lowered in energy.

  6. Extending the random-phase approximation for electronic correlation energies: the renormalized adiabatic local density approximation

    DEFF Research Database (Denmark)

    Olsen, Thomas; Thygesen, Kristian S.

    2012-01-01

    while chemical bond strengths and absolute correlation energies are systematically underestimated. In this work we extend the RPA by including a parameter-free renormalized version of the adiabatic local-density (ALDA) exchange-correlation kernel. The renormalization consists of a (local) truncation...... of the ALDA kernel for wave vectors q > 2kF, which is found to yield excellent results for the homogeneous electron gas. In addition, the kernel significantly improves both the absolute correlation energies and atomization energies of small molecules over RPA and ALDA. The renormalization can...

  7. Ergodic Properties of Local Spectral Density for a Conservative System of Coupled Quantum States

    CERN Document Server

    Starovoitov, V S

    2002-01-01

    The shape and the inverse participation ratio (IPR) of local spectral density (LSD) are studied for a generic isolated system of coupled quantum states, the Hamiltonian of which is represented by a band random matrix with the disordered leading diagonal. We find for the matrices with arbitrary small band that the lack of ergodicity for LSD can be associated with an exponential increase in IPR with the ratio $v/\\Delta_c$ ($v$ - the root of mean square for off-diagonal matrix elements, $\\Delta_c$ - the energy spacing between directly coupled basis states). Criterions specifying transition to localization and ergodicity for LSD are considered.

  8. Relationships among red-cockaded woodpecker group density, nestling provisioning rates, and habitat

    Science.gov (United States)

    Richard N. Conner; D. Craig Rudolph; Richard R. Schaefer; Daniel Saenz; Clifford E. Shackelford

    1999-01-01

    We examined Red-cockaded Woodpecker (Picoides borealis) food provisioning rates of nestlings during the 1992 and 1993 breeding seasons on the Vernon Ranger District of the Kisatchie National Forest in Louisiana. Provisioning rates were monitored at nest trees in moderate (9.8 groups/2 km radius, n=10) and low (5.9 groups/2 km radius, n=10) density...

  9. Fitting density models to observational data - The local Schmidt law in molecular clouds

    CERN Document Server

    Lombardi, Marco; Alves, João

    2013-01-01

    We consider the general problem of fitting a parametric density model to discrete observations, taken to follow a non-homogeneous Poisson point process. This class of models is very common, and can be used to describe many astrophysical processes, including the distribution of protostars in molecular clouds. We give the expression for the likelihood of a given spatial density distribution of protostars and apply it to infer the most probable dependence of the protostellar surface density on the gas surface density. Finally, we apply this general technique to model the distribution of protostars in the Orion molecular cloud and robustly derive the local star formation scaling (Schmidt) law for a molecular cloud. We find that in this cloud the protostellar surface density, \\Sigma_YSO, is directly proportional to the square gas column density, here expressed as infrared extinction in the K-band, A_K: more precisely, \\Sigma_YSO = (1.65 +/- 0.19) A_K^(2.03 +/- 0.15) stars pc^-2.

  10. Supernova matter at subnuclear densities as a resonant Fermi gas: enhancement of neutrino rates.

    Science.gov (United States)

    Bartl, A; Pethick, C J; Schwenk, A

    2014-08-22

    At low energies nucleon-nucleon interactions are resonant and therefore supernova matter at subnuclear densities has many similarities to atomic gases with interactions dominated by a Feshbach resonance. We calculate the rates of neutrino processes involving nucleon-nucleon collisions and show that these are enhanced in mixtures of neutrons and protons at subnuclear densities due to the large scattering lengths. As a result, the rate for neutrino pair bremsstrahlung and absorption is significantly larger below 10(13) g cm(-3) compared to rates used in supernova simulations.

  11. Localized operator partitioning method for electronic excitation energies in the time-dependent density functional formalism

    CERN Document Server

    Nagesh, Jayashree; Brumer, Paul; Izmaylov, Artur F

    2016-01-01

    We extend the localized operator partitioning method (LOPM) [J. Nagesh, A.F. Izmaylov, and P. Brumer, J. Chem. Phys. 142, 084114 (2015)] to the time-dependent density functional theory (TD-DFT) framework to partition molecular electronic energies of excited states in a rigorous manner. A molecular fragment is defined as a collection of atoms using Stratman-Scuseria-Frisch atomic partitioning. A numerically efficient scheme for evaluating the fragment excitation energy is derived employing a resolution of the identity to preserve standard one- and two-electron integrals in the final expressions. The utility of this partitioning approach is demonstrated by examining several excited states of two bichromophoric compounds: 9-((1-naphthyl)-methyl)-anthracene and 4-((2-naphthyl)-methyl)-benzaldehyde. The LOPM is found to provide nontrivial insights into the nature of electronic energy localization that are not accessible using simple density difference analysis.

  12. Universal dynamics of density correlations at the transition to the many-body localized state

    Science.gov (United States)

    Mierzejewski, M.; Herbrych, J.; Prelovšek, P.

    2016-12-01

    Within one-dimensional disordered models of interacting fermions, we perform a numerical study of several dynamical density correlations, which can serve as hallmarks of the transition to the many-body localized state. The results confirm that density-wave correlations exhibit quite an abrupt change with increasing disorder, with a nonvanishing long-time value characteristic for the nonergodic phase. In addition, our results reveal a logarithmic variation of correlations in time in a wide time window, which we can bring in connection with the anomalous behavior of the dynamical conductivity near the transition. Our results support the view that the transition to many-body localization can be characterized by universal dynamical exponents.

  13. The Van der Waals interaction of the hydrogen molecule an exact local energy density functional

    CERN Document Server

    Choy, T C

    1999-01-01

    We verify that the van der Waals interaction and hence all dispersion interactions for the hydrogen molecule given by: W''= -{A/R^6}-{B/R^8}-{C/R^10}- ..., in which R is the internuclear separation, are exactly soluble. The constants A=6.4990267..., B=124.3990835 ... and C=1135.2140398... (in Hartree units) first obtained approximately by Pauling and Beach (PB) [1] using a linear variational method, can be shown to be obtainable to any desired accuracy via our exact solution. In addition we shall show that a local energy density functional can be obtained, whose variational solution rederives the exact solution for this problem. This demonstrates explicitly that a static local density functional theory exists for this system. We conclude with remarks about generalising the method to other hydrogenic systems and also to helium.

  14. Water dynamics: relation between hydrogen bond bifurcations, molecular jumps, local density & hydrophobicity.

    Science.gov (United States)

    Titantah, John Tatini; Karttunen, Mikko

    2013-10-21

    Structure and dynamics of water remain a challenge. Resolving the properties of hydrogen bonding lies at the heart of this puzzle. We employ ab initio Molecular Dynamics (AIMD) simulations over a wide temperature range. The total simulation time was ≈ 2 ns. Both bulk water and water in the presence of a small hydrophobic molecule were simulated. We show that large-angle jumps and bond bifurcations are fundamental properties of water dynamics and that they are intimately coupled to both local density and hydrogen bond strength oscillations in scales from about 60 to a few hundred femtoseconds: Local density differences are the driving force for bond bifurcations and the consequent large-angle jumps. The jumps are intimately connected to the recently predicted hydrogen bond energy asymmetry. Our analysis also appears to confirm the existence of the so-called negativity track provided by the lone pairs of electrons on the oxygen atom to enable water rotation.

  15. Probing the local density of states in three dimensions with a scanning single quantum emitter

    CERN Document Server

    Schell, Andreas W; Benson, Oliver

    2013-01-01

    Their intrinsic properties render single quantum systems as ideal tools for quantum enhanced sensing and microscopy. As an additional benefit, their size is typically on an atomic scale which enables sensing with very high spatial resolution. Here, we report on utilizing a single nitrogen vacancy center in nanodiamond for performing three-dimensional scanning-probe fluorescence lifetime imaging microscopy. By measuring changes of the single emitter's lifetime information on the local density of optical states is acquired at the nanoscale. This technique to gather information on the local density of optical states is important for the understanding of fundamental quantum optical processes as well as for the engineering of novel photonic and plasmonic devices.

  16. Generation of localized magnetic moments in the charge-density-wave state

    Science.gov (United States)

    Akzyanov, Ramil S.; Rozhkov, Alexander V.

    2015-08-01

    We propose a mechanism explaining the generation of localized magnetic moments in charge-density-wave compounds. Our model Hamiltonian describes an Anderson impurity placed in a host material exhibiting the charge-density wave. There is a region of the model's parameter space, where even weak Coulomb repulsion on the impurity site is able to localize the magnetic moment on the impurity. The phase diagram of a single impurity at T = 0 is mapped. To establish the connection with experiment, the thermodynamic properties of a random impurity ensemble is studied. Magnetic susceptibility of the ensemble diverges at low temperature; heat capacity as a function of the magnetic field demonstrates pronounced low field peak. Both features are consistent with experiments on orthorhombic TaS3 and blue bronze.

  17. Global hybrids from the semiclassical atom theory satisfying the local density linear response

    CERN Document Server

    Fabiano, E; Cortona, P; Della Sala, F

    2015-01-01

    We propose global hybrid approximations of the exchange-correlation (XC) energy functional which reproduce well the modified fourth-order gradient expansion of the exchange energy in the semiclassical limit of many-electron neutral atoms and recover the full local density approximation (LDA) linear response. These XC functionals represent the hybrid versions of the APBE functional [Phys. Rev. Lett. 106, 186406, (2011)] yet employing an additional correlation functional which uses the localization concept of the correlation energy density to improve the compatibility with the Hartree-Fock exchange as well as the coupling-constant-resolved XC potential energy. Broad energetical and structural testings, including thermochemistry and geometry, transition metal complexes, non-covalent interactions, gold clusters and small gold-molecule interfaces, as well as an analysis of the hybrid parameters, show that our construction is quite robust. In particular, our testing shows that the resulting hybrid, including 20\\% o...

  18. Band theoretical investigation of substituted CrO2 within the local density approximation

    OpenAIRE

    1994-01-01

    The effects of substitutions at différent concentrations within the lattice of CrO2 are investigated assuming ordered configurations. For this purpose we use self-consistent band structure calculations based on the local spin density approximation. All results show an antiparallel spin alignment between host Cr and the substitutional M = Ir, Os, Pt. Depending on the nature of M and its concentration, CrO2 transforms from a half metallic ferromagnet to a halfmetallic or metallic ferrimagnet.

  19. Green Function Approach to the Calculation of the Local Density of States in the Graphitic Nanocone

    Directory of Open Access Journals (Sweden)

    Smotlacha Jan

    2016-01-01

    Full Text Available Graphene and other nanostructures belong to the center of interest of today’s physics research. The local density of states of the graphitic nanocone influenced by the spin–orbit interaction was calculated. Numerical calculations and the Green function approach were used to solve this problem. It was proven in the second case that the second order approximation is not sufficient for this purpose.

  20. Enhanced toroidal flow stabilization of edge localized modes with increased plasma density

    Science.gov (United States)

    Cheng, Shikui; Zhu, Ping; Banerjee, Debabrata

    2017-09-01

    Toroidal flow alone is generally thought to have an important influence on tokamak edge pedestal stability, even though theoretical analysis often predicts merely a weak stabilizing effect of toroidal flow on the edge localized modes (ELMs) in experimental parameter regimes. For the first time, we find from two-fluid MHD calculations that such a stabilization, however, can be significantly enhanced by increasing the edge plasma density. Our finding resolves a long-standing mystery whether or how toroidal rotation can indeed have an effective influence on ELMs, and explains why the ELM mitigation and suppression by toroidal rotation are more favorably achieved in higher collisionality regime in recent experiments. The finding suggests a new control scheme on modulating toroidal flow stabilization of ELMs with plasma density, along with a new additional constraint on the optimal level of plasma density for the desired edge plasma conditions.

  1. A simple local correlation energy functional for spherically confined atoms from ab initio correlation energy density.

    Science.gov (United States)

    Vyboishchikov, Sergei F

    2017-09-03

    We propose a simple method of calculating the electron correlation energy density e_c(r) and the correlation potential V_c(r) from second-order Møller-Plesset amplitudes and its generalization for the case of a Configuration Interaction wavefunction, based on Nesbet's theorem. The correlation energy density obtained by this method for free and spherically confined Be and He atoms was employed to fit a local analytical density functional based on Wigner's functional. The functional is capable to reproduce a strong increase of the correlation energy with decreasing the confined radius for the Be atom. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. The Local Galaxy Density and the Arm Class of Spiral Galaxies

    CERN Document Server

    Giuricin, G; Mardirossian, F; Mezzetti, M

    1993-01-01

    We have examined the effect of the environmental density on the arm classification of an extensive sample of spiral galaxies included in the Nearby Galaxy Catalog (Tully, 1988a). We have also explored the dependence of the arm class of a galaxy on other factors, such as its blue absolute magnitude and its disk-to-total mass ratio, inferred in the literature either from the gradient of a good galaxy rotation curve or from a photometric mass decomposition method. We have found that the arm class is strongly related to the absolute magnitude in the mid-type spirals (in the sense that grand design galaxies are, on average, more luminous than flocculent objects), whilst this relation is considerably weaker in the early and late types. In general the influence of the local density on the arm structure appears to be much weaker than that of the absolute magnitude. The local density acts essentially in strengthening the arm class--absolute magnitude relation for the mid types, whereas no environmental density effects...

  3. Using the electron localization function to correct for confinement physics in semi-local density functional theory.

    Science.gov (United States)

    Hao, Feng; Armiento, Rickard; Mattsson, Ann E

    2014-05-14

    We have previously proposed that further improved functionals for density functional theory can be constructed based on the Armiento-Mattsson subsystem functional scheme if, in addition to the uniform electron gas and surface models used in the Armiento-Mattsson 2005 functional, a model for the strongly confined electron gas is also added. However, of central importance for this scheme is an index that identifies regions in space where the correction provided by the confined electron gas should be applied. The electron localization function (ELF) is a well-known indicator of strongly localized electrons. We use a model of a confined electron gas based on the harmonic oscillator to show that regions with high ELF directly coincide with regions where common exchange energy functionals have large errors. This suggests that the harmonic oscillator model together with an index based on the ELF provides the crucial ingredients for future improved semi-local functionals. For a practical illustration of how the proposed scheme is intended to work for a physical system we discuss monoclinic cupric oxide, CuO. A thorough discussion of this system leads us to promote the cell geometry of CuO as a useful benchmark for future semi-local functionals. Very high ELF values are found in a shell around the O ions, and take its maximum value along the Cu-O directions. An estimate of the exchange functional error from the effect of electron confinement in these regions suggests a magnitude and sign that could account for the error in cell geometry.

  4. Parallel and Low-Order Scaling Implementation of Hartree-Fock Exchange Using Local Density Fitting.

    Science.gov (United States)

    Köppl, Christoph; Werner, Hans-Joachim

    2016-07-12

    Calculations using modern linear-scaling electron-correlation methods are often much faster than the necessary reference Hartree-Fock (HF) calculations. We report a newly implemented HF program that speeds up the most time-consuming step, namely, the evaluation of the exchange contributions to the Fock matrix. Using localized orbitals and their sparsity, local density fitting (LDF), and atomic orbital domains, we demonstrate that the calculation of the exchange matrix scales asymptotically linearly with molecular size. The remaining parts of the HF calculation scale cubically but become dominant only for very large molecular sizes or with many processing cores. The method is well parallelized, and the speedup scales well with up to about 100 CPU cores on multiple compute nodes. The effect of the local approximations on the accuracy of computed HF and local second-order Møller-Plesset perturbation theory energies is systematically investigated, and default values are established for the parameters that determine the domain sizes. Using these values, calculations for molecules with hundreds of atoms in combination with triple-ζ basis sets can be carried out in less than 1 h, with just a few compute nodes. The method can also be used to speed up density functional theory calculations with hybrid functionals that contain HF exchange.

  5. Localized form of Fock terms in nuclear covariant density functional theory

    CERN Document Server

    Liang, Haozhao; Ring, Peter; Roca-Maza, Xavier; Meng, Jie

    2012-01-01

    In most of the successful versions of covariant density functional theory in nuclei, the Fock terms are not included explicitly, which leads to local functionals and forms the basis of their widespread applicability at present. However, it has serious consequences for the description of Gamow-Teller resonances (GTR) and spin-dipole resonances (SDR) which can only be cured by adding further phenomenological parameters. Relativistic Hartree-Fock models do not suffer from these problems. They can successfully describe the GTR and SDR as well as the isovector part of the Dirac effective mass without any additional parameters. However, they are non-local and require considerable numerical efforts. By the zero-range reduction and the Fierz transformation, a new method is proposed to take into account the Fock terms in local functionals, which retains the simplicity of conventional models and provides proper descriptions of the spin-isospin channels and the Dirac masses.

  6. 3D Velocity and Density Reconstructions of the Local Universe with Cosmicflows-1

    CERN Document Server

    Courtois, Helene M; Tully, R Brent; Gottlober, Stefan

    2011-01-01

    This paper presents an analysis of the local peculiar velocity field based on the Wiener Filter reconstruction method. We used our currently available catalog of distance measurements containing 1,797 galaxies within 3000 km/s: Cosmicflows-1. The Wiener Filter method is used to recover the full 3D peculiar velocity field from the observed map of radial velocities and to recover the underlying linear density field. The velocity field within a data zone of 3000 km/s is decomposed into a local component that is generated within the data zone and a tidal one that is generated by the mass distribution outside that zone. The tidal component is characterized by a coherent flow toward the Norma-Hydra-Centaurus (Great Attractor) region while the local component is dominated by a flow toward the Virgo Cluster and away from the Local Void. A detailed analysis shows that the local flow is predominantly governed by the Local Void and the Virgo Cluster plays a lesser role. The analysis procedure was tested against a mock c...

  7. Influence of Seeding Rate on Weed Density in Soybean Planting System for Southeastern Coastal Plains

    Directory of Open Access Journals (Sweden)

    Pawel Wiatrak

    2011-01-01

    Full Text Available Problem statement: Increasing seeding rates may help decrease weed pressure in soybean [Glycine max (L. Merr.] wide row spacing. Approach: The objective of this study was to evaluate the influence of five glyphosate-resistant soybean Maturity Groups (MG (IV, V, VI, VII and VIII and six seeding rates (68,000,136,000, 204,000, 272,000, 340,000 and 408,000 seeds ha-1 on weed density under dryland conditions on the Southeastern coastal plain in 2007-2009. Results: Weed decrease with increasing seeding rate varied over years. Weed density was generally lower at higher seeding rates for most MG soybeans at 30 and 60 DAP, except MG IV and VIII at 30 DAP in 2007 and MG VI at 30 DAP in 2008. At 60 DAP, soybean leaf area index (LAI and normalized difference vegetation index (NDVI were greater with lower weed density. Conclusion: Additionally, negative correlations were observed between weed density and plant LAI/NDVI for all MG in 2008 and MG IV through VI in 2009. These results suggest that increased seeding rates may help decrease weed pressure and improve soybean growth at early growth stages. However the response of weed pressure to seeding rate may vary over years and depend on MG soybean.

  8. Critical desertification transition in semi-arid ecosystems: The role of local facilitation and colonization rate

    Science.gov (United States)

    Corrado, Raffaele; Cherubini, Anna Maria; Pennetta, Cecilia

    2015-05-01

    In this work we study the effect of two different ecological mechanisms on the desertification transition in arid or semi-arid ecosystems, modeled by a stochastic cellular automaton. Namely we consider the role of the facilitation mechanism, i.e. the local positive effects of plants on their neighborhood and of colonization factors, such as seed production, survival and germination probabilities. Within the model, the strength of these two mechanisms is determined by the parameters f and b, respectively controlling the rates of the recovery and colonization processes. In particular we focus on the full desertification transition occurring at increasing value of the mortality rate m and we discuss how the values of f and b affect the critical mortality mc , the critical exponents β and γσ‧, determining the power-law scaling of the average vegetation density and of the root-mean-square deviation of the density fluctuations, and the character of the transition: continuous or abrupt. We show that mc strongly depends on both f and b, a dependence which accounts for the higher resilience of the ecosystems to external stresses as a consequence of an increased effectiveness of positive feedback effects. On the other hand, concerning the value of the exponents and the character of the transition, our results point out that both these features are unaffected by changes in the strength of the local facilitation. Viceversa, we show that an increase of the colonization factor b significantly modifies the values of the exponents and the order of the transition, changing a continuous transition into an abrupt one. We explain these results in terms of the different range of the interactions characterizing facilitation and colonization mechanisms.

  9. Impact of the pedestal plasma density on dynamics of edge localized mode crashes and energy loss scaling

    Energy Technology Data Exchange (ETDEWEB)

    Xu, X. Q., E-mail: xxu@llnl.gov [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Ma, J. F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute for Fusion Studies, University of Texas, Austin, Texas 78712 (United States); Li, G. Q. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China)

    2014-12-15

    The latest BOUT++ studies show an emerging understanding of dynamics of edge localized mode (ELM) crashes and the consistent collisionality scaling of ELM energy losses with the world multi-tokamak database. A series of BOUT++ simulations are conducted to investigate the scaling characteristics of the ELM energy losses vs collisionality via a density scan. Linear results demonstrate that as the pedestal collisionality decreases, the growth rate of the peeling-ballooning modes decreases for high n but increases for low n (1 < n < 5), therefore the width of the growth rate spectrum γ(n) becomes narrower and the peak growth shifts to lower n. Nonlinear BOUT++ simulations show a two-stage process of ELM crash evolution of (i) initial bursts of pressure blob and void creation and (ii) inward void propagation. The inward void propagation stirs the top of pedestal plasma and yields an increasing ELM size with decreasing collisionality after a series of micro-bursts. The pedestal plasma density plays a major role in determining the ELM energy loss through its effect on the edge bootstrap current and ion diamagnetic stabilization. The critical trend emerges as a transition (1) linearly from ballooning-dominated states at high collisionality to peeling-dominated states at low collisionality with decreasing density and (2) nonlinearly from turbulence spreading dynamics at high collisionality into avalanche-like dynamics at low collisionality.

  10. SUSY constraints from relic density: High sensitivity to pre-BBN expansion rate

    Energy Technology Data Exchange (ETDEWEB)

    Arbey, A. [Universite de Lyon, Lyon F-69000 (France); Universite Lyon 1, Villeurbanne F-69622 (France); Centre de Recherche Astrophysique de Lyon, Observatoire de Lyon, 9 avenue Charles Andre, Saint-Genis Laval cedex F-69561 (France); CNRS, UMR 5574, Ecole Normale Superieure de Lyon, Lyon (France)], E-mail: arbey@obs.univ-lyon1.fr; Mahmoudi, F. [High Energy Physics, Uppsala University, Box 535, 75121 Uppsala (Sweden)

    2008-10-30

    The sensitivity of the lightest supersymmetric particle relic density calculation to the variation of the cosmological expansion rate before nucleosynthesis is discussed. Such a modification of the expansion rate, even extremely modest and with no consequence on the cosmological observations, can greatly enhance the calculated relic density, and therefore change the constraints on the SUSY parameter space drastically. We illustrate this variation in two examples of SUSY models, and show that it is unsafe to use the lower bound of the WMAP limits in order to constrain supersymmetry. We therefore suggest to use only the upper value {omega}{sub DM}h{sup 2}<0.135.

  11. Rates of gyrase supercoiling and transcription elongation control supercoil density in a bacterial chromosome.

    Directory of Open Access Journals (Sweden)

    Nikolay Rovinskiy

    Full Text Available Gyrase catalyzes negative supercoiling of DNA in an ATP-dependent reaction that helps condense bacterial chromosomes into a compact interwound "nucleoid." The supercoil density (σ of prokaryotic DNA occurs in two forms. Diffusible supercoil density (σ(D moves freely around the chromosome in 10 kb domains, and constrained supercoil density (σ(C results from binding abundant proteins that bend, loop, or unwind DNA at many sites. Diffusible and constrained supercoils contribute roughly equally to the total in vivo negative supercoil density of WT cells, so σ = σ(C+σ(D. Unexpectedly, Escherichia coli chromosomes have a 15% higher level of σ compared to Salmonella enterica. To decipher critical mechanisms that can change diffusible supercoil density of chromosomes, we analyzed strains of Salmonella using a 9 kb "supercoil sensor" inserted at ten positions around the genome. The sensor contains a complete Lac operon flanked by directly repeated resolvase binding sites, and the sensor can monitor both supercoil density and transcription elongation rates in WT and mutant strains. RNA transcription caused (- supercoiling to increase upstream and decrease downstream of highly expressed genes. Excess upstream supercoiling was relaxed by Topo I, and gyrase replenished downstream supercoil losses to maintain an equilibrium state. Strains with TS gyrase mutations growing at permissive temperature exhibited significant supercoil losses varying from 30% of WT levels to a total loss of σ(D at most chromosome locations. Supercoil losses were influenced by transcription because addition of rifampicin (Rif caused supercoil density to rebound throughout the chromosome. Gyrase mutants that caused dramatic supercoil losses also reduced the transcription elongation rates throughout the genome. The observed link between RNA polymerase elongation speed and gyrase turnover suggests that bacteria with fast growth rates may generate higher supercoil densities

  12. The Structure, Density, and Local Environment Distribution in Ab Initio Liquid Water

    Science.gov (United States)

    Santra, Biswajit; Distasio, Robert A., Jr.; Wu, Xifan; Car, Roberto

    2014-03-01

    We have performed extensive ab initio molecular dynamics (AIMD) simulations of liquid water at ambient conditions in the canonical (NVT) and isothermal-isobaric (NPT) ensembles to understand the individual and collective importance of exact exchange, van der Waals interactions, and nuclear quantum effects on the structural properties of liquid water. AIMD simulations which include these effects result in oxygen-oxygen radial distribution functions which are in excellent agreement with experiments and a liquid water structure having an equilibrium density within 1% of the experimental value of 1 g/cm3. A detailed analysis of the distribution of local structure in ambient liquid water has revealed that the inherent potential energy surface is bimodal with respect to high- and low-density molecular environments, consistent with the existence of polymorphism in the amorphous phases of water. With these findings in mind, the methodology presented herein overcomes the well-known limitations of semi-local density functional theory (GGA-DFT) providing a detailed and accurate microscopic description of ambient liquid water. DOE: DE-SC0008626, DOE: DE-SC0005180, NSF: CHE-0956500.

  13. Implants delivering bisphosphonate locally increase periprosthetic bone density in an osteoporotic sheep model. A pilot study

    Directory of Open Access Journals (Sweden)

    GVA Stadelmann

    2008-07-01

    Full Text Available It is a clinical challenge to obtain a sufficient orthopaedic implant fixation in weak osteoporotic bone. When the primary implant fixation is poor, micromotions occur at the bone-implant interface, activating osteoclasts, which leads to implant loosening. Bisphosphonate can be used to prevent the osteoclastic response, but when administered systemically its bioavailability is low and the time it takes for the drug to reach the periprosthetic bone may be a limiting factor. Recent data has shown that delivering bisphosphonate locally from the implant surface could be an interesting solution. Local bisphosphonate delivery increased periprosthetic bone density, which leads to a stronger implant fixation, as demonstrated in rats by the increased implant pullout force. The aim of the present study was to verify the positive effect on periprosthetic bone remodelling of local bisphosphonate delivery in an osteoporotic sheep model. Four implants coated with zoledronate and two control implants were inserted in the femoral condyle of ovariectomized sheep for 4 weeks. The bone at the implant surface was 50% higher in the zoledronate-group compared to control group. This effect was significant up to a distance of 400µm from the implant surface. The presented results are similar to what was observed in the osteoporotic rat model, which suggest that the concept of releasing zoledronate locally from the implant to increase the implant fixation is not species specific. The results of this trial study support the claim that local zoledronate could increase the fixation of an implant in weak bone.

  14. Lightfront holography and area density of entropy associated with quantum localization on wedge-horizon

    Energy Technology Data Exchange (ETDEWEB)

    Schroer, Bert [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mail: schroer@cbpf.br

    2002-08-01

    The lightfront quantization of the 70s is reviewed in the more rigorous setting of lightfront (LF) restriction of free fields in which the lightfront is considered to be linear extension of the upper causal horizon of a wedge region. Particular attention is given to the change of localization structure in passing from the wedge to its horizon which results in the emergence of a transverse quantum mechanical substructure of the QFT on the horizon and its lightfront extension. The vacuum fluctuations of QFT on the LF are compressed into the direction of the lightray (where they become associated with a chiral QFT) and lead to the notion of area density of a 'split localization' entropy. To overcome the limitation of this restriction approach and include interacting theories with non-canonical short distance behavior, we introduce a new concept of algebraic lightfront holography which uses ideas of algebraic QFT, in particular the modular structure of its associated local operator algebras. In this way the localization properties of LF degrees of freedom including the absence of transverse vacuum fluctuations are confirmed to be stable against interactions. The important universality aspect of lightfront holography is emphasized. Only in this way one is able to extract from the 'split-localization' entropy a split-independent additive entropy-like measure of the entanglement of the vacuum upon restriction to the horizon algebra. (author)

  15. Identification of Essential Proteins Based on a New Combination of Local Interaction Density and Protein Complexes.

    Directory of Open Access Journals (Sweden)

    Jiawei Luo

    Full Text Available Computational approaches aided by computer science have been used to predict essential proteins and are faster than expensive, time-consuming, laborious experimental approaches. However, the performance of such approaches is still poor, making practical applications of computational approaches difficult in some fields. Hence, the development of more suitable and efficient computing methods is necessary for identification of essential proteins.In this paper, we propose a new method for predicting essential proteins in a protein interaction network, local interaction density combined with protein complexes (LIDC, based on statistical analyses of essential proteins and protein complexes. First, we introduce a new local topological centrality, local interaction density (LID, of the yeast PPI network; second, we discuss a new integration strategy for multiple bioinformatics. The LIDC method was then developed through a combination of LID and protein complex information based on our new integration strategy. The purpose of LIDC is discovery of important features of essential proteins with their neighbors in real protein complexes, thereby improving the efficiency of identification.Experimental results based on three different PPI(protein-protein interaction networks of Saccharomyces cerevisiae and Escherichia coli showed that LIDC outperformed classical topological centrality measures and some recent combinational methods. Moreover, when predicting MIPS datasets, the better improvement of performance obtained by LIDC is over all nine reference methods (i.e., DC, BC, NC, LID, PeC, CoEWC, WDC, ION, and UC.LIDC is more effective for the prediction of essential proteins than other recently developed methods.

  16. Identification of Essential Proteins Based on a New Combination of Local Interaction Density and Protein Complexes

    Science.gov (United States)

    Luo, Jiawei; Qi, Yi

    2015-01-01

    Background Computational approaches aided by computer science have been used to predict essential proteins and are faster than expensive, time-consuming, laborious experimental approaches. However, the performance of such approaches is still poor, making practical applications of computational approaches difficult in some fields. Hence, the development of more suitable and efficient computing methods is necessary for identification of essential proteins. Method In this paper, we propose a new method for predicting essential proteins in a protein interaction network, local interaction density combined with protein complexes (LIDC), based on statistical analyses of essential proteins and protein complexes. First, we introduce a new local topological centrality, local interaction density (LID), of the yeast PPI network; second, we discuss a new integration strategy for multiple bioinformatics. The LIDC method was then developed through a combination of LID and protein complex information based on our new integration strategy. The purpose of LIDC is discovery of important features of essential proteins with their neighbors in real protein complexes, thereby improving the efficiency of identification. Results Experimental results based on three different PPI(protein-protein interaction) networks of Saccharomyces cerevisiae and Escherichia coli showed that LIDC outperformed classical topological centrality measures and some recent combinational methods. Moreover, when predicting MIPS datasets, the better improvement of performance obtained by LIDC is over all nine reference methods (i.e., DC, BC, NC, LID, PeC, CoEWC, WDC, ION, and UC). Conclusions LIDC is more effective for the prediction of essential proteins than other recently developed methods. PMID:26125187

  17. Low frame rate video target localization and tracking testbed

    Science.gov (United States)

    Pang, Yu; Shen, Dan; Chen, Genshe; Liang, Pengpeng; Pham, Khanh; Blasch, Erik; Wang, Zhonghai; Ling, Haibin

    2013-05-01

    Traditional tracking frameworks are challenged by low video frame rate scenarios, because the appearances and locations of the target may change considerably in consecutive frames. Our paper presents a saliency-based temporal association dependency (STAD) framework to deal with such a low frame rate scenario and demonstrate good results in our robot testbed. We first use median filter to create a background of the scene, then apply background subtraction to every new frame to decide the rough position of the target. With the help of the markers on the robots, we use a gradient voting algorithm to detect the high responses of the directions of the robots. Finally, a template matching with branch pruning is used to obtain the finer estimation of the pose of the robots. To make the tracking-by-detection framework stable, we further introduce the temporal constraints using a previously detected result as well as an association technique. Our experiments show that our method can achieve a very stable tracking result and outperforms some state-of-the-art trackers such as Meanshift, Online-AdaBoosting, Mulitple-Instance-Learning, Tracking-Learning-Detection etc. Also. we demonstrate that our algorithm provides near real-time solutions given the low frame rate requirement.

  18. Where Does the Density Localize? Convergent Behavior for Global Hybrids, Range Separation, and DFT+U

    CERN Document Server

    Gani, Terry Z H

    2016-01-01

    Approximate density functional theory (DFT) suffers from many-electron self- interaction error, otherwise known as delocalization error, that may be diagnosed and then corrected through elimination of the deviation from exact piecewise linear behavior between integer electron numbers. Although paths to correction of energetic delocalization error are well- established, the impact of these corrections on the electron density is less well-studied. Here, we compare the effect on density delocalization of DFT+U, global hybrid tuning, and range- separated hybrid tuning on a diverse test set of 32 transition metal complexes and observe the three methods to have qualitatively equivalent effects on the ground state density. Regardless of valence orbital diffuseness (i.e., from 2p to 5p), ligand electronegativity (i.e., from Al to O), basis set (i.e., plane wave versus localized basis set), metal (i.e., Ti, Fe, Ni) and spin state, or tuning method, we consistently observe substantial charge loss at the metal and gain ...

  19. The dipole moment of the spin density as a local indicator for phase transitions

    Science.gov (United States)

    Schmitz, D.; Schmitz-Antoniak, C.; Warland, A.; Darbandi, M.; Haldar, S.; Bhandary, S.; Eriksson, O.; Sanyal, B.; Wende, H.

    2014-07-01

    The intra-atomic magnetic dipole moment - frequently called term - plays an important role in the determination of spin magnetic moments by x-ray absorption spectroscopy for systems with nonspherical spin density distributions. In this work, we present the dipole moment as a sensitive monitor to changes in the electronic structure in the vicinity of a phase transiton. In particular, we studied the dipole moment at the Fe2+ and Fe3+ sites of magnetite as an indicator for the Verwey transition by a combination of x-ray magnetic circular dichroism and density functional theory. Our experimental results prove that there exists a local change in the electronic structure at temperatures above the Verwey transition correlated to the known spin reorientation. Furthermore, it is shown that measurement of the dipole moment is a powerful tool to observe this transition in small magnetite nanoparticles for which it is usually screened by blocking effects in classical magnetometry.

  20. Local distortion in Co-doped LSMO from entropy-maximized charge density distribution

    Energy Technology Data Exchange (ETDEWEB)

    Syed Ali, K.S. [Department of Physics, The Madura College, Madurai 625011 (India); Saravanan, R., E-mail: saragow@dataone.i [Department of Physics, The Madura College, Madurai 625011 (India); Pashchenko, A.V.; Pashchenko, V.P. [Galkin Donetsk Institute of Physics and Technology, National Academy of Sciences of Ukraine, Donetsk 83114 (Ukraine)

    2010-07-09

    Perovskite structure manganites La{sub 0.67}Sr{sub 0.22}Mn{sub 1.11-x}Co{sub x}O{sub 3} were prepared by the solid state reaction method. An X-ray analysis of the structure was undertaken using the Rietveld technique on the experimental powder X-ray diffraction data and, then, a charge density distribution study was undertaken, using the maximum entropy method (MEM). The charge density in the unit cell was reconstructed and the effect of Co{sup 3+} doping in the Mn-O matrix was studied. Local distortions due to Co doping were analyzed and the results are now discussed.

  1. The dipole moment of the spin density as a local indicator for phase transitions.

    Science.gov (United States)

    Schmitz, D; Schmitz-Antoniak, C; Warland, A; Darbandi, M; Haldar, S; Bhandary, S; Eriksson, O; Sanyal, B; Wende, H

    2014-07-21

    The intra-atomic magnetic dipole moment - frequently called ⟨Tz⟩ term - plays an important role in the determination of spin magnetic moments by x-ray absorption spectroscopy for systems with nonspherical spin density distributions. In this work, we present the dipole moment as a sensitive monitor to changes in the electronic structure in the vicinity of a phase transiton. In particular, we studied the dipole moment at the Fe(2+) and Fe(3+) sites of magnetite as an indicator for the Verwey transition by a combination of x-ray magnetic circular dichroism and density functional theory. Our experimental results prove that there exists a local change in the electronic structure at temperatures above the Verwey transition correlated to the known spin reorientation. Furthermore, it is shown that measurement of the dipole moment is a powerful tool to observe this transition in small magnetite nanoparticles for which it is usually screened by blocking effects in classical magnetometry.

  2. Negative relationships between population density and metabolic rates are not general.

    Science.gov (United States)

    Yashchenko, Varvara; Fossen, Erlend Ignacio; Kielland, Øystein Nordeide; Einum, Sigurd

    2016-07-01

    Population density has recently been suggested to be an important factor influencing metabolic rates and to represent an important 'third axis' explaining variation beyond that explained by body mass and temperature. In situations where population density influences food consumption, the immediate effect on metabolism acting through specific dynamic action (SDA), and downregulation due to fasting over longer periods, is well understood. However, according to a recent review, previous studies suggest a more general effect of population density per se, even in the absence of such effects. It has been hypothesized that this results from animals performing anticipatory responses (i.e. reduced activity) to expected declines in food availability. Here, we test the generality of this finding by measuring density effects on metabolic rates in 10 clones from two different species of the zooplankton Daphnia (Daphnia pulex Leydig and D. magna Straus). Using fluorescence-based respirometry, we obtain high-precision measures of metabolism. We also identify additional studies on this topic that were not included in the previous review, compare the results and evaluate the potential for measurement bias in all previous studies. We demonstrate significant variation in mass-specific metabolism among clones within both species. However, we find no evidence for a negative relationship between population density and mass-specific metabolism. The previously reported pattern also disappeared when we extended the set of studies analysed. We discuss potential reasons for the discrepancy among studies, including two main sources of potential bias (microbial respiration and declining oxygen consumption due to reduced oxygen availability). Only one of the previous studies gives sufficient information to conclude the absence of such biases, and consistent with our results, no effect of density on metabolism was found. We conclude that population density per se does not have a general effect

  3. Implications for Galaxy Evolution from the Cosmic Evolution of Supernova Rate Density

    CERN Document Server

    Oda, T; Yasuda, N; Sumi, T; Morokuma, T; Doi, M; Kosugi, G

    2008-01-01

    We report a comprehensive statistical analysis of the observational data of the cosmic evolution of supernova (SN) rate density, to derive constraints on cosmic star formation history and the nature of type Ia supernova (SN Ia) progenitor. We use all available information of magnitude, SN type, and redshift information of both type Ia and core-collapse (CC) SNe in GOODS and SDF, as well as SN Ia rate densities reported in the literature. Furthermore, we also add 157 SN candidates in the past Subaru/Suprime-Cam data that are newly reported here, to increase the statistics. We find that the current data set of SN rate density evolution already gives a meaningful constraint on the evolution of the cosmic star formation rate (SFR) at z <~ 1, though strong constraints cannot be derived for the delay time distribution (DTD) of SNe Ia. We derive a constraint of the evolutionary index of SFR density alpha ~ 3--4 [(1+z)^alpha at z <~ 1] with an evidence for a significant evolution of mean extinction of CC SNe [E...

  4. Landau hamiltonians with random potentials localization and the density of states

    CERN Document Server

    Combes, J M; Combes, J M; Hislop, P D

    1994-01-01

    We prove the existence of localized states at the edges of the bands for the two-dimensional Landau Hamiltonian with a random potential, of arbitrary disorder, provided that the magnetic field is sufficiently large. The corresponding eigenfunctions decay exponentially with the magnetic field and distance. We also prove that the integrated density of states is Lipschitz continuous away from the Landau energies. The proof relies on a Wegner estimate for the finite-area magnetic Hamiltonians with random potentials and exponential decay estimates for the finite-area Green's functions. The proof of the decay estimates for the Green's functions uses fundamental results from two-dimensional bond percolation theory.

  5. A convergent scheme for a non-local coupled system modelling dislocations densities dynamics

    Science.gov (United States)

    Hajj, A. El; Forcadel, N.

    2008-06-01

    In this paper, we study a non-local coupled system that arises in the theory of dislocations densities dynamics. Within the framework of viscosity solutions, we prove a long time existence and uniqueness result for the solution of this model. We also propose a convergent numerical scheme and we prove a Crandall-Lions type error estimate between the continuous solution and the numerical one. As far as we know, this is the first error estimate of Crandall-Lions type for Hamilton-Jacobi systems. We also provide some numerical simulations.

  6. Landau parameters for energy density functionals generated by local finite-range pseudopotentials

    CERN Document Server

    Idini, Andrea; Dobaczewski, Jacek

    2016-01-01

    In Landau theory of Fermi liquids, the particle-hole interaction near the Fermi energy in different spin-isospin channels is probed in terms of an expansion over the Legendre polynomials. This provides a useful and efficient way to constrain properties of nuclear energy density functionals in symmetric nuclear matter and finite nuclei. In this study, we present general expressions for Landau parameters corresponding to a two-body central local regularized pseudopotential. We also show results obtained for two recently adjusted NLO and N$^2$LO parametrizations. Such pseudopotentials will be used to determine mean-field and beyond-mean-field properties of paired nuclei across the entire nuclear chart.

  7. Micromagnetic model for studies on Magnetic Tunnel Junction switching dynamics, including local current density

    Energy Technology Data Exchange (ETDEWEB)

    Frankowski, Marek, E-mail: mfrankow@agh.edu.pl; Czapkiewicz, Maciej; Skowronski, Witold; Stobiecki, Tomasz

    2014-02-15

    We present a model introducing the Landau–Lifshitz–Gilbert equation with a Slonczewski's Spin-Transfer-Torque (STT) component in order to take into account spin polarized current influence on the magnetization dynamics, which was developed as an Object Oriented MicroMagnetic Framework extension. We implement the following computations: magnetoresistance of vertical channels is calculated from the local spin arrangement, local current density is used to calculate the in-plane and perpendicular STT components as well as the Oersted field, which is caused by the vertical current flow. The model allows for an analysis of all listed components separately, therefore, the contribution of each physical phenomenon in dynamic behavior of Magnetic Tunnel Junction (MTJ) magnetization is discussed. The simulated switching voltage is compared with the experimental data measured in MTJ nanopillars.

  8. Resolving phase information of the optical local density of state with scattering near-field probes

    Science.gov (United States)

    Prasad, R.; Vincent, R.

    2016-10-01

    We theoretically discuss the link between the phase measured using a scattering optical scanning near-field microscopy (s-SNOM) and the local density of optical states (LDOS). A remarkable result is that the LDOS information is directly included in the phase of the probe. Therefore by monitoring the spatial variation of the trans-scattering phase, we locally measure the phase modulation associated with the probe and the optical paths. We demonstrate numerically that a technique involving two-phase imaging of a sample with two different sized tips should allow to obtain the image the pLDOS. For this imaging method, numerical comparison with extinction probe measurement shows crucial qualitative and quantitative improvement.

  9. Adaptive Localization of Focus Point Regions via Random Patch Probabilistic Density from Whole-Slide, Ki-67-Stained Brain Tumor Tissue

    Directory of Open Access Journals (Sweden)

    Yazan M. Alomari

    2015-01-01

    Full Text Available Analysis of whole-slide tissue for digital pathology images has been clinically approved to provide a second opinion to pathologists. Localization of focus points from Ki-67-stained histopathology whole-slide tissue microscopic images is considered the first step in the process of proliferation rate estimation. Pathologists use eye pooling or eagle-view techniques to localize the highly stained cell-concentrated regions from the whole slide under microscope, which is called focus-point regions. This procedure leads to a high variety of interpersonal observations and time consuming, tedious work and causes inaccurate findings. The localization of focus-point regions can be addressed as a clustering problem. This paper aims to automate the localization of focus-point regions from whole-slide images using the random patch probabilistic density method. Unlike other clustering methods, random patch probabilistic density method can adaptively localize focus-point regions without predetermining the number of clusters. The proposed method was compared with the k-means and fuzzy c-means clustering methods. Our proposed method achieves a good performance, when the results were evaluated by three expert pathologists. The proposed method achieves an average false-positive rate of 0.84% for the focus-point region localization error. Moreover, regarding RPPD used to localize tissue from whole-slide images, 228 whole-slide images have been tested; 97.3% localization accuracy was achieved.

  10. Adaptive localization of focus point regions via random patch probabilistic density from whole-slide, Ki-67-stained brain tumor tissue.

    Science.gov (United States)

    Alomari, Yazan M; Sheikh Abdullah, Siti Norul Huda; MdZin, Reena Rahayu; Omar, Khairuddin

    2015-01-01

    Analysis of whole-slide tissue for digital pathology images has been clinically approved to provide a second opinion to pathologists. Localization of focus points from Ki-67-stained histopathology whole-slide tissue microscopic images is considered the first step in the process of proliferation rate estimation. Pathologists use eye pooling or eagle-view techniques to localize the highly stained cell-concentrated regions from the whole slide under microscope, which is called focus-point regions. This procedure leads to a high variety of interpersonal observations and time consuming, tedious work and causes inaccurate findings. The localization of focus-point regions can be addressed as a clustering problem. This paper aims to automate the localization of focus-point regions from whole-slide images using the random patch probabilistic density method. Unlike other clustering methods, random patch probabilistic density method can adaptively localize focus-point regions without predetermining the number of clusters. The proposed method was compared with the k-means and fuzzy c-means clustering methods. Our proposed method achieves a good performance, when the results were evaluated by three expert pathologists. The proposed method achieves an average false-positive rate of 0.84% for the focus-point region localization error. Moreover, regarding RPPD used to localize tissue from whole-slide images, 228 whole-slide images have been tested; 97.3% localization accuracy was achieved.

  11. Effects of low-density feeding on elk–fetus contact rates on Wyoming feedgrounds

    Science.gov (United States)

    Creech, Tyler G.; Cross, Paul C.; Scurlock, Brandon M.; Maichak, Eric J.; Rogerson, Jared D.; Henningsen, John C.; Creel, Scott

    2012-01-01

    High seroprevalance for Brucella abortus among elk on Wyoming feedgrounds suggests that supplemental feeding may influence parasite transmission and disease dynamics by altering the rate at which elk contact infectious materials in their environment. We used proximity loggers and video cameras to estimate rates of elk-to-fetus contact (the primary source of brucellosis transmission) during winter supplemental feeding. We compared contact rates during high-density and low-density (LD) feeding treatments that provided the same total amount of food distributed over different areas. Low-density feeding led to >70% reductions in total number of contacts and number of individuals contacting a fetus. Proximity loggers and video cameras provided similar estimates of elk–fetus contact rates. Elk contacted fetuses and random control points equally, suggesting that elk were not attracted to fetuses but encountered them incidentally while feeding. The modeled relationship between contact rate and disease prevalence is nonlinear and LD feeding may result in large reductions in brucellosis prevalence, but this depends on the amount of transmission that occurs on and off feedgrounds.

  12. Influence of electron screening on electron capture rate under high density of stellar interior

    Institute of Scientific and Technical Information of China (English)

    罗志全; 彭秋和

    1996-01-01

    The influence of electron screening on electron capture rate in strong screening is investigated, in which the Gamow-Teller resonance transition is considered and the matrix elements for the resonance transition are calculated on the basis of a shell model. The effect of electron screening on electron capture by 56Co is discussed. It is shown that the screening decreases evidently the capture rates in lower temperature and higher density. The effect of electron screening on other nuclear capture rates is estimated. The conclusion derived may influence the research for late stellar evolution and supernova explosion.

  13. Simple models for complex systems: exploiting the relationship between local and global densities.

    Science.gov (United States)

    Pascual, Mercedes; Roy, Manojit; Laneri, Karina

    2011-01-01

    Simple temporal models that ignore the spatial nature of interactions and track only changes in mean quantities, such as global densities, are typically used under the unrealistic assumption that individuals are well mixed. These so-called mean-field models are often considered overly simplified, given the ample evidence for distributed interactions and spatial heterogeneity over broad ranges of scales. Here, we present one reason why such simple population models may work even when mass-action assumptions do not hold: spatial structure is present but it relates to global densities in a special way. With an individual-based predator-prey model that is spatial and stochastic, and whose mean-field counterpart is the classic Lotka-Volterra model, we show that the global densities and densities of pairs (or spatial covariances) establish a bi-power law at the stationary state and also in their transient approach to this state. This relationship implies that the dynamics of global densities can be written simply as a function of those densities alone without invoking pairs (or higher order moments). The exponents of the bi-power law for the predation rate exhibit a remarkable robustness to changes in model parameters. Evidence is presented for a connection of our findings to the existence of a critical phase transition in the dynamics of the spatial system. We discuss the application of similar modified mean-field equations to other ecological systems for which similar transitions have been described, both in models and empirical data.Electronic supplementary material The online version of this article (doi:10.1007/s12080-011-0116-2) contains supplementary material, which is available to authorized users.

  14. A new access density definition and its correlation with crash rates by microscopic traffic simulation method.

    Science.gov (United States)

    Huang, Bing; Zhang, Yu; Lu, Linjun; Lu, Jian John

    2014-03-01

    Better access management can improve highway safety by reducing potential crashes and conflicts. To make adequate access management decisions, it is essential to understand the impact of different access types on roadway safety, usually represented by the crash rate of a roadway segment. The objective of this paper is to propose a new access density definition reflecting the impact of traffic speed variation of different access types. The traffic speed variation was obtained from a microscopic traffic simulation software package TSIS-CORSIM. A sample roadway Temple Terrace Highway was selected to perform traffic simulation. Access Weight was obtained from traffic speed variation, and access density was obtained from access weight. The proposed access density was then compared with the existing definition by analyzing their correlations with crash rates on one suburban street in Temple Terrace, Florida. The comparison demonstrates that crash rates are more highly correlated with the proposed access density than that in the previous study, which is helpful for Federal Highway Administration (FHWA), United States Department of Transportation (USDOT), and transportation consulting companies to regulate the construction, management and design of roadway segments.

  15. Reconstructing the insulin secretion rate by Bayesian deconvolution of phase-type densities

    DEFF Research Database (Denmark)

    Andersen, Kim Emil; Højbjerre, Malene

    2005-01-01

    of the insulin secretion rate (ISR) can be done by solving a highly ill-posed deconvolution problem. We represent the ISR, the C-peptide concentration and the convolution kernel as scaled phase-type densities and develop a Bayesian methodology for estimating such densities via Markov chain Monte Carlo techniques....... Hereby closed form evaluation of ISR is possible. We demonstrate the methodology on experimental data from healthy subjects and obtain results which are more realistic than recently reported conclusions based upon methods where the ISR is considered as piecewise constant....

  16. Characteristic of Secondary Flow Caused by Local Density Change in Standing Acoustic Fields

    Science.gov (United States)

    Tonsho, Kazuyuki; Hirosawa, Takuya; Kusakawa, Hiroshi; Kuwahara, Takuo; Tanabe, Mitsuaki

    Secondary flow is a flow which is caused by the interference between standing acoustic fields and local density change. The behavior of the secondary flow depends on the location of the given local density change in the standing acoustic fields. When the density change is given at the middle of a velocity node and the neighboring velocity anti-node (middle point) or when it is given at the velocity anti-node in standing acoustic fields, the secondary flow shows particular behavior. Characteristic of the secondary flow at the two positions was predicted by numerical simulations. It was examined from these simulations whether the driving mechanism of the flow can be explained by the kind of acoustic radiation force that has been proposed so far. The predicted secondary flow was verified by experiments. For both the simulations and experiments, the standing acoustic fields generated in a cylinder are employed. In the experiments, the acoustic fields are generated by two loud speakers that are vibrated in same phase in a chamber. The employed resonance frequency is about 1000 Hz. The chamber is filled with air of room temperature and atmospheric pressure. In the numerical simulations and experiments, the local density change is given by heating or cooling. Because the secondary flow is influenced by buoyancy, the numerical simulations were done without taking gravity force into account and a part of the experiments were done by the microgravity condition using a drop tower. As a result of the simulations, at the middle point, the heated air was blown toward the node and the cooled air was blown toward the anti-node. It is clarified that the secondary flow is driven by the expected kind of acoustic radiation force. At the anti-node, both the heated and cooled air expands perpendicular to the traveling direction of the sound wave. The driving mechanism of the secondary flow can not be explained by the acoustic radiation force, and a detailed analysis is done. Through the

  17. Effect of surface structure of kaolinite on aggregation, settling rate, and bed density.

    Science.gov (United States)

    Du, Jianhua; Morris, Gayle; Pushkarova, Rada A; Smart, Roger St C

    2010-08-17

    The flocculation and solid/liquid separation of four well-characterized kaolinites (2 well, 2 poorly crystallized) have been studied for comparison of surface structure (SEM), aggregate structure during flocculation (cryo-SEM), settling rate, and bed density (with raking). It is shown that major differences in these properties are largely due to crystallinity and consequent surface structure of the extensive (larger dimension "basal") face. Well-crystallized kaolinites, with higher Hinckley indices and lower aspect ratios, have relatively smooth, flat basal surfaces and thicker edge planes promoting both effective initial bridging flocculation (largely edge-edge) and structural rearrangement to face-face during the raking process. This results in faster settling rates and more compact bed structures. Poorly crystallized kaolinites, with low Hinckley indices and high aspect ratios, exhibit ragged, stepped structures of the extensive face with a high proportion of nanosized islands forming cascade-like steps (i.e., multiple edges) contributing up to 30% of the specific surface area and providing flocculant adsorption sites (hydroxyl groups) across this extensive face. This leads to bridging flocculation taking place on both edge and extensive ("basal") planes, producing low-density edge-face structures during flocculation which leads to slow settling rates and poor bed densities. In particular, the complex surface morphology of the poorly crystallized kaolinites resists the transformation of edge-face structures to dense face-face structures under shear force introduced by raking. This results in low sediment density for poorly crystallized kaolinites. The studies suggest that the main influence on settling rates and bed densities of kaolinites in mineral tailings is likely to be related to the crystallinity and surface morphology of the kaolinite. They also suggest that interpretation of kaolinite behavior based on models of a flat (001) basal plane and edge sites

  18. Variations in the Galactic star formation rate and density thresholds for star formation

    CERN Document Server

    Longmore, S N; Testi, L; Purcell, C R; Walsh, A J; Bressert, E; Pestalozzi, M; Molinari, S; Ott, J; Cortese, L; Battersby, C; Murray, N; Lee, E; Kruijssen, D

    2012-01-01

    The conversion of gas into stars is a fundamental process in astrophysics and cosmology. Stars are known to form from the gravitational collapse of dense clumps in interstellar molecular clouds, and it has been proposed that the resulting star formation rate is proportional to either the amount of mass above a threshold gas surface density, or the gas volume density. These star-formation prescriptions appear to hold in nearby molecular clouds in our Milky Way Galaxy's disk as well as in distant galaxies where the star formation rates are often much larger. The inner 500 pc of our Galaxy, the Central Molecular Zone (CMZ), contains the largest concentration of dense, high-surface density molecular gas in the Milky Way, providing an environment where the validity of star-formation prescriptions can be tested. Here we show that by several measures, the current star formation rate in the CMZ is an order-of-magnitude lower than the rates predicted by the currently accepted prescriptions. In particular, the region 1...

  19. A New Measurement of the Electron Density in the Local Interstellar Medium

    Science.gov (United States)

    Wood, Brian E.; Linsky, Jeffrey L.

    1997-01-01

    Using the echelle-A grating of the Goddard High-Resolution Spectrograph, we have observed the C II λλ1335, 1336 emission lines of the nearby (d = 13.3 pc) star system Capella (G8 III + G1 III). Interstellar C II absorption features are detected within both stellar emission lines. The ground-state and excited-state C II column densities derived from these absorption lines imply an electron density of ne = 0.11+0.12-0.06 cm-3 in the local interstellar medium (LISM). Unlike previous derivations of ne from Mg II/Mg I ratios, the density suggested by the C II lines is independent of assumptions about ionization equilibrium. Current estimates of the H I density in the LISM are in the range 0.1-0.2 cm-3. The He I/H I ratio toward the white dwarf G191-B2B, which is only 7° from Capella, has been measured to be He I/H I = 0.068-0.082 from the Extreme-Ultraviolet Explorer data. These results indicate hydrogen and helium ionization fractions toward Capella of X(H) = 0.45 +/- 0.25 and X(He) = 0.57 +/- 0.23, respectively, confirming that hydrogen and helium are substantially ionized in the LISM. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy Inc., under NASA contract NAS5-26555.

  20. The impact of local stellar radiation on the HI column density distribution

    CERN Document Server

    Rahmati, Alireza; Pawlik, Andreas H; Raičević, Milan

    2013-01-01

    It is often assumed that local sources of ionizing radiation have little impact on the distribution of HI in the post-reionization Universe. While this is a good assumption for the IGM, analytic arguments suggest that local sources may typically be more important than the background radiation for high column density absorbers (N_HI > 10^17 /cm^2). We post-process cosmological simulations with accurate radiation transport to investigate the impact of local stellar sources on the HI distribution. We demonstrate that the limited numerical resolution and the simplified treatment of the ISM that are typical of current cosmological simulations provide significant challenges, but that many of the problems can be overcome by taking two steps. First, using ISM particles rather than stellar particles as sources results in a much better sampling of the source distribution. Second, by rescaling the source luminosities so that the amount of radiation escaping into the IGM agrees with that required to produce the observed ...

  1. Dependence of the outer density profiles of halos on their mass accretion rate

    Energy Technology Data Exchange (ETDEWEB)

    Diemer, Benedikt; Kravtsov, Andrey V., E-mail: bdiemer@oddjob.uchicago.edu [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States)

    2014-07-01

    We present a systematic study of the density profiles of ΛCDM halos, focusing on the outer regions, 0.1 < r/R {sub vir} < 9. We show that the median and mean profiles of halo samples of a given peak height exhibit significant deviations from the universal analytic profiles discussed previously in the literature, such as the Navarro-Frenk-White and Einasto profiles, at radii r ≳ 0.5R {sub 200m}. In particular, at these radii the logarithmic slope of the median density profiles of massive or rapidly accreting halos steepens more sharply than predicted. The steepest slope of the profiles occurs at r ≈ R {sub 200m}, and its absolute value increases with increasing peak height or mass accretion rate, reaching slopes of –4 and steeper. Importantly, we find that the outermost density profiles at r ≳ R {sub 200m} are remarkably self-similar when radii are rescaled by R {sub 200m}. This self-similarity indicates that radii defined with respect to the mean density are preferred for describing the structure and evolution of the outer profiles. However, the inner density profiles are most self-similar when radii are rescaled by R {sub 200c}. We propose a new fitting formula that describes the median and mean profiles of halo samples selected by their peak height or mass accretion rate with accuracy ≲ 10% at all radii, redshifts, and masses we studied, r ≲ 9R {sub vir}, 0 < z < 6, and M {sub vir} > 1.7 × 10{sup 10} h {sup –1} M {sub ☉}. We discuss observational signatures of the profile features described above and show that the steepening of the outer profile should be detectable in future weak-lensing analyses of massive clusters. Such observations could be used to estimate the mass accretion rate of cluster halos.

  2. Quantum efficiency of self-assembled quantum dots determined by a modified optical local density of states

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Stobbe, Søren; Nikolaev, I.S.

    2007-01-01

    We have measured time-resolved spontaneous emission from quantum dots near a dielectric interface with known photonic local density of states. We thus experimentally determine the quantum efficiency and the dipole moment, important for quantum optics.......We have measured time-resolved spontaneous emission from quantum dots near a dielectric interface with known photonic local density of states. We thus experimentally determine the quantum efficiency and the dipole moment, important for quantum optics....

  3. High-pressure pulsed avalanche discharges: Formulas for required preionization density and rate for homogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Brenning, N.; Axnaes, I.; Nilsson, J.O.; Eninger, J.E. [Royal Inst. of Tech., Stockholm (Sweden)

    1997-02-01

    The requirements on preionization for the formation of spatially homogeneous pulsed avalanche discharges are examined. The authors derive two formulas which apply in the case of a slowly rising electric field, one which gives the required preionization density at breakdown, and one which gives the required preionization rate. These quantities are expressed as functions of the electrochemical properties of the gas, the neutral density, and the electric field rise time. They also treat the statistical effect that the electrons tend to form groups, in contrast to being randomly distributed in space, during the prebreakdown phase. This process is found to increase the required preionization rate significantly, typically by a factor of five for a discharge at atmospheric pressure. Homogeneous high-pressure discharges have been used for laser excitation, and have also been proposed for chemical plasma processing (ozone production) because of their good scaling properties and high efficiency.

  4. Mechanical characterization of particulate aluminum foams. Strain-rate, density and matrix alloy versus adhesive effects

    Energy Technology Data Exchange (ETDEWEB)

    Lehmhus, Dirk [ISIS Sensorial Materials Scientific Centre, University of Bremen (Germany); Baumeister, Joachim; Stutz, Lennart; Stoebener, Karsten [Fraunhofer IFAM Bremen (Germany); Schneider, Eduard [University of Bremen (Germany); Avalle, Massimiliano; Peroni, Lorenzo; Peroni, Marco [Dipartimento di Meccanica, Politecnico di Torino Vercelli (Italy)

    2010-07-15

    The study evaluates mechanical properties of APM particulate aluminum foams built up from adhesively bonded Al foam spheres. Foams of matrix alloy AlSi10 are compared, with PM AlSi7 foams used as reference. The influence of density is studied both for quasi-static and dynamic compressive loading in a range from {proportional_to}0.35 to 0.71 g cm{sup -3}. The effect of varying the bonding agent is evaluated for a single density and both strain rate levels by replacing the standard, high-strength epoxy-based adhesive with a polyamide of greatly increased ductility. The result is a clear shift of fracture events to higher strain levels, as well as the introduction of a strain-rate dependency of strength. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  5. Maximization of ICRF power by SOL density tailoring with local gas injection

    Science.gov (United States)

    Jacquet, P.; Goniche, M.; Bobkov, V.; Lerche, E.; Pinsker, R. I.; Pitts, R. A.; Zhang, W.; Colas, L.; Hosea, J.; Moriyama, S.; Wang, S.-J.; Wukitch, S.; Zhang, X.; Bilato, R.; Bufferand, H.; Guimarais, L.; Faugel, H.; Hanson, G. R.; Kocan, M.; Monakhov, I.; Noterdaeme, J.-M.; Petrzilka, V.; Shaw, A.; Stepanov, I.; Sips, A. C. C.; Van Eester, D.; Wauters, T.; JET contributors, the; the ASDEX Upgrade Team; the DIII-D Team; ITPA ‘Integrated Operation Scenarios' members, the; experts

    2016-04-01

    Experiments have been performed under the coordination of the International Tokamak Physics Activity (ITPA) on several tokamaks, including ASDEX Upgrade (AUG), JET and DIII-D, to characterize the increased Ion cyclotron range of frequency (ICRF) antenna loading achieved by optimizing the position of gas injection relative to the RF antennas. On DIII-D, AUG and JET (with the ITER-Like Wall) a 50% increase in the antenna loading was observed when injecting deuterium in ELMy H-mode plasmas using mid-plane inlets close to the powered antennas instead of divertor injection and, with smaller improvement when using gas inlets located at the top of the machine. The gas injection rate required for such improvements (~0.7  ×  1022 el s-1 in AUG, ~1.0  ×  1022 el s-1 in JET) is compatible with the use of this technique to optimize ICRF heating during the development of plasma scenarios and no degradation of confinement was observed when using the mid-plane or top inlets compared with divertor valves. An increase in the scrape-off layer (SOL) density was measured when switching gas injection from divertor to outer mid-plane or top. On JET and DIII-D, the measured SOL density increase when using main chamber puffing is consistent with the antenna coupling resistance increase provided that the distance between the measurement lines of sight and the injection location is taken into account. Optimized gas injection was also found to be beneficial for reducing tungsten (W) sputtering at the AUG antenna limiters, and also to reduce slightly the W and nickel (Ni) content in JET plasmas. Modeling the specific effects of divertor/top/mid-plane injection on the outer mid-plane density was carried out using both the EDGE2D-EIRENE and EMC3-EIRENE plasma boundary code packages; simulations indeed indicate that outer mid-plane gas injection maximizes the density in the mid-plane close to the injection point with qualitative agreement with the AUG SOL density measurements

  6. On the rate of convergence of the maximum likelihood estimator of a k-monotone density

    Institute of Scientific and Technical Information of China (English)

    WELLNER; Jon; A

    2009-01-01

    Bounds for the bracketing entropy of the classes of bounded k-monotone functions on [0,A] are obtained under both the Hellinger distance and the Lp(Q) distance,where 1 p < ∞ and Q is a probability measure on [0,A].The result is then applied to obtain the rate of convergence of the maximum likelihood estimator of a k-monotone density.

  7. On the rate of convergence of the maximum likelihood estimator of a K-monotone density

    Institute of Scientific and Technical Information of China (English)

    GAO FuChang; WELLNER Jon A

    2009-01-01

    Bounds for the bracketing entropy of the classes of bounded K-monotone functions on [0, A] are obtained under both the Hellinger distance and the LP(Q) distance, where 1 ≤ p < ∞ and Q is a probability measure on [0, A]. The result is then applied to obtain the rate of convergence of the maximum likelihood estimator of a K-monotone density.

  8. Localization of endocardial ectopic activity by means of noninvasive endocardial surface current density reconstruction

    Science.gov (United States)

    Lai, Dakun; Liu, Chenguang; Eggen, Michael D.; Iaizzo, Paul A.; He, Bin

    2011-07-01

    Localization of the source of cardiac ectopic activity has direct clinical benefits for determining the location of the corresponding ectopic focus. In this study, a recently developed current-density (CD)-based localization approach was experimentally evaluated in noninvasively localizing the origin of the cardiac ectopic activity from body-surface potential maps (BSPMs) in a well-controlled experimental setting. The cardiac ectopic activities were induced in four well-controlled intact pigs by single-site pacing at various sites within the left ventricle (LV). In each pacing study, the origin of the induced ectopic activity was localized by reconstructing the CD distribution on the endocardial surface of the LV from the measured BSPMs and compared with the estimated single moving dipole (SMD) solution and precise pacing site (PS). Over the 60 analyzed beats corresponding to ten pacing sites (six for each), the mean and standard deviation of the distance between the locations of maximum CD value and the corresponding PSs were 16.9 mm and 4.6 mm, respectively. In comparison, the averaged distance between the SMD locations and the corresponding PSs was slightly larger (18.4 ± 3.4 mm). The obtained CD distribution of activated sources extending from the stimulus site also showed high consistency with the endocardial potential maps estimated by a minimally invasive endocardial mapping system. The present experimental results suggest that the CD method is able to locate the approximate site of the origin of a cardiac ectopic activity, and that the distribution of the CD can portray the propagation of early activation of an ectopic beat.

  9. Automatic processing of high-rate, high-density multibeam echosounder data

    Science.gov (United States)

    Calder, B. R.; Mayer, L. A.

    2003-06-01

    Multibeam echosounders (MBES) are currently the best way to determine the bathymetry of large regions of the seabed with high accuracy. They are becoming the standard instrument for hydrographic surveying and are also used in geological studies, mineral exploration and scientific investigation of the earth's crustal deformations and life cycle. The significantly increased data density provided by an MBES has significant advantages in accurately delineating the morphology of the seabed, but comes with the attendant disadvantage of having to handle and process a much greater volume of data. Current data processing approaches typically involve (computer aided) human inspection of all data, with time-consuming and subjective assessment of all data points. As data rates increase with each new generation of instrument and required turn-around times decrease, manual approaches become unwieldy and automatic methods of processing essential. We propose a new method for automatically processing MBES data that attempts to address concerns of efficiency, objectivity, robustness and accuracy. The method attributes each sounding with an estimate of vertical and horizontal error, and then uses a model of information propagation to transfer information about the depth from each sounding to its local neighborhood. Embedded in the survey area are estimation nodes that aim to determine the true depth at an absolutely defined location, along with its associated uncertainty. As soon as soundings are made available, the nodes independently assimilate propagated information to form depth hypotheses which are then tracked and updated on-line as more data is gathered. Consequently, we can extract at any time a "current-best" estimate for all nodes, plus co-located uncertainties and other metrics. The method can assimilate data from multiple surveys, multiple instruments or repeated passes of the same instrument in real-time as data is being gathered. The data assimilation scheme is

  10. The relationship between drainage density, erosion rate, and hilltop curvature: Implications for sediment transport processes

    Science.gov (United States)

    Clubb, Fiona J.; Mudd, Simon M.; Attal, Mikaël.; Milodowski, David T.; Grieve, Stuart W. D.

    2016-10-01

    Drainage density is a fundamental landscape metric describing the extent of the fluvial network. We compare the relationship between drainage density (Dd) and erosion rate (E) using the Channel-Hillslope Integrated Landscape Development (CHILD) numerical model. We find that varying the channel slope exponent (n) in detachment-limited fluvial incision models controls the relationship between Dd and E, with n > 1 resulting in increasing Dd with E if all other parameters are held constant. This result is consistent when modeling both linear and nonlinear hillslope sediment flux. We also test the relationship between Dd and E in five soil-mantled landscapes throughout the USA: Feather River, CA; San Gabriel Mountains, CA; Boulder Creek, CO; Guadalupe Mountains, NM; and Bitterroot National Forest, ID. For two of these field sites we compare Dd to cosmogenic radionuclide (CRN)-derived erosion rates, and for each site we use mean hilltop curvature as a proxy for erosion rate where CRN-derived erosion rates are not available. We find that there is a significant positive relationship between Dd, E, and hilltop curvature across every site, with the exception of the San Gabriel Mountains, CA. This relationship is consistent with an n exponent greater than 1, suggesting that at higher erosion rates, the transition between advective and diffusive processes occurs at smaller contributing areas in soil-mantled landscapes.

  11. Tailoring correlations of the local density of states in disordered photonic materials

    CERN Document Server

    Riboli, F; Monaco, G; Caselli, N; Intonti, F; Gurioli, M; Skipetrov, S E

    2016-01-01

    We present experimental evidence for the different mechanisms driving the fluctuations of the local density of states (LDOS) in disordered photonic systems. We establish a clear link between the microscopic structure of the material and the frequency correlation function of LDOS accessed by a near-field hyperspectral imaging technique. We show, in particular, that short- and long-range frequency correlations of LDOS are controlled by different physical processes (multiple or single scattering processes, respectively) that can be---to some extent---manipulated independently. We also demonstrate that the single scattering contribution to the LDOS fluctuations is sensitive to subwavelength features of the material and, in particular, to the correlation length of its dielectric function. Our work paves the way towards a complete control of statistical properties of disordered photonic systems, allowing for designing materials with predefined LDOS correlations.

  12. Directional Local Density of States of Classical and Quantum Propagating Surface Plasmons

    Science.gov (United States)

    Berthel, Martin; Jiang, Quanbo; Pham, Aline; Bellessa, Joel; Genet, Cyriaque; Huant, Serge; Drezet, Aurélien

    2017-01-01

    We theoretically and experimentally introduce the concept of the local density of states (LDOS) associated with propagative surface plasmons (PSPs) launched along a structured thin gold film (a concept we call PSP LDOS). The alternative method couples a near-field optical microscope, in either the classical or the quantum regime of excitation, to a far-field leakage-radiation microscope. This method allows for selecting and collecting a very narrow portion of the directional SP wave vectors, thereby offering sufficient resolution to probe the collimation efficiency of a SP beam for a source near the focal point of a Bragg parabolic reflector. We are able to build and image the PSP LDOS in a fully integrated quantum SP launcher by depositing a diamond nanocrystal hosting nitrogen-vacancy centers at the focal point of the mirror. Our demonstration of the PSP LDOS with quantized SPs offers alternative prospects in the field of quantum plasmonics.

  13. Structure of Eigenstates and Local Spectral Density of States A Three-Orbital Schematic Shell Model

    CERN Document Server

    Wang, W; Casati, G; Wang, Wen-ge

    1998-01-01

    The average shape of the Spectral Local Density of States (LDOS) and eigenfunctions (EFs) has been studied numerically for a conservative dynamical model (three-orbital Lipkin-Meshkov-Glick model) which can exhibit strong chaos in the classical limit. The attention is paid to the comparison of the shape of LDOS with that known for random matrix models, as well as to the shape of the EFs, for different values of the perturbation strength. The classical counterparts of the LDOS has also been studied and found in a remarkable agreement with the quantum calculations. Finally, by making use of a generalization of Brillouin- Wigner perturbation expansion, the form of long tails of LDOS and EFs is given analytically and confirmed numerically.

  14. Local Density-of-States Mapping in Photonic Crystal Resonators by Deterministically Positioned Germanium Quantum Dots

    CERN Document Server

    Schatzl, Magdalena; Glaser, Martin; Brehm, Moritz; Simbula, Angelica; Galli, Matteo; Fromherz, Thomas; Schäffler, Friedrich

    2016-01-01

    We report on mapping of the local density of states in L3 photonic crystal resonators (PCR) via deterministically positioned single Ge quantum dots (QDs). Perfect site-control of Ge QDs on pre-patterned silicon-on-insulator substrates was exploited to fabricate in one processing run almost 300 L3 PCRs containing single QDs in systematically varying positions in the cavities. The alignment precision of the QD emitters was better than 20 nm. This type of parallel processing is essentially based on standard Si device technologies and is therefore scalable to any number and configuration of PCR structures. As a first demonstrator, we probed the coupling efficiency of a single Ge QD to the L3 cavity modes as a function of their spatial overlap. The results are in excellent agreement with finite-difference time-domain simulations.

  15. Towards a Density Functional Theory Exchange-Correlation Functional able to describe localization/delocalization

    Science.gov (United States)

    Mattsson, Ann E.; Wills, John M.

    2013-03-01

    The inability to computationally describe the physics governing the properties of actinides and their alloys is the poster child of failure of existing Density Functional Theory exchange-correlation functionals. The intricate competition between localization and delocalization of the electrons, present in these materials, exposes the limitations of functionals only designed to properly describe one or the other situation. We will discuss the manifestation of this competition in real materials and propositions on how to construct a functional able to accurately describe properties of these materials. I addition we will discuss both the importance of using the Dirac equation to describe the relativistic effects in these materials, and the connection to the physics of transition metal oxides. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. Broadband enhancement of local density of states using silicon-compatible hyperbolic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu; Inampudi, Sandeep; Capretti, Antonio [Department of Electrical and Computer Engineering and Photonics Center, Boston University, 8 Saint Mary' s Street Boston, Massachusetts 02215 (United States); Sugimoto, Hiroshi [Department of Electrical and Computer Engineering and Photonics Center, Boston University, 8 Saint Mary' s Street Boston, Massachusetts 02215 (United States); Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501 (Japan); Fujii, Minoru [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501 (Japan); Dal Negro, Luca, E-mail: dalnegro@bu.edu [Department of Electrical and Computer Engineering and Photonics Center, Boston University, 8 Saint Mary' s Street Boston, Massachusetts 02215 (United States); Division of Materials Science and Engineering, Boston University, 15 Saint Mary' s Street, Brookline, Massachusetts 02446 (United States)

    2015-06-15

    Light emitting silicon quantum dots by colloidal synthesis were uniformly spin-coated into a 20 nm-thick film and deposited atop a hyperbolic metamaterial of alternating TiN and SiO{sub 2} sub-wavelength layers. Using steady-state and time-resolved photoluminescence spectroscopy as a function of the emission wavelength in partnership with rigorous electromagnetic modeling of dipolar emission, we demonstrate enhanced Local Density of States and coupling to high-k modes in a broad spectral range. These findings provide an alternative approach for the engineering of novel Si-compatible broadband sources that leverage the control of radiative transitions in hyperbolic metamaterials and the flexibility of the widespread Si platform.

  17. Entrainment Rate in Shallow Cumuli: Dependence on Entrained Dry Air Sources and Probability Density Functions

    Science.gov (United States)

    Lu, C.; Liu, Y.; Niu, S.; Vogelmann, A. M.

    2012-12-01

    In situ aircraft cumulus observations from the RACORO field campaign are used to estimate entrainment rate for individual clouds using a recently developed mixing fraction approach. The entrainment rate is computed based on the observed state of the cloud core and the state of the air that is laterally mixed into the cloud at its edge. The computed entrainment rate decreases when the air is entrained from increasing distance from the cloud core edge; this is because the air farther away from cloud edge is drier than the neighboring air that is within the humid shells around cumulus clouds. Probability density functions of entrainment rate are well fitted by lognormal distributions at different heights above cloud base for different dry air sources (i.e., different source distances from the cloud core edge). Such lognormal distribution functions are appropriate for inclusion into future entrainment rate parameterization in large scale models. To the authors' knowledge, this is the first time that probability density functions of entrainment rate have been obtained in shallow cumulus clouds based on in situ observations. The reason for the wide spread of entrainment rate is that the observed clouds are affected by entrainment mixing processes to different extents, which is verified by the relationships between the entrainment rate and cloud microphysics/dynamics. The entrainment rate is negatively correlated with liquid water content and cloud droplet number concentration due to the dilution and evaporation in entrainment mixing processes. The entrainment rate is positively correlated with relative dispersion (i.e., ratio of standard deviation to mean value) of liquid water content and droplet size distributions, consistent with the theoretical expectation that entrainment mixing processes are responsible for microphysics fluctuations and spectral broadening. The entrainment rate is negatively correlated with vertical velocity and dissipation rate because entrainment

  18. Many-body localization and transition by density matrix renormalization group and exact diagonalization studies

    Science.gov (United States)

    Lim, S. P.; Sheng, D. N.

    2016-07-01

    A many-body localized (MBL) state is a new state of matter emerging in a disordered interacting system at high-energy densities through a disorder-driven dynamic phase transition. The nature of the phase transition and the evolution of the MBL phase near the transition are the focus of intense theoretical studies with open issues in the field. We develop an entanglement density matrix renormalization group (En-DMRG) algorithm to accurately target highly excited states for MBL systems. By studying the one-dimensional Heisenberg spin chain in a random field, we demonstrate the accuracy of the method in obtaining energy eigenstates and the corresponding statistical results of quantum states in the MBL phase. Based on large system simulations by En-DMRG for excited states, we demonstrate some interesting features in the entanglement entropy distribution function, which is characterized by two peaks: one at zero and another one at the quantized entropy S =ln2 with an exponential decay tail on the S >ln2 side. Combining En-DMRG with exact diagonalization simulations, we demonstrate that the transition from the MBL phase to the delocalized ergodic phase is driven by rare events where the locally entangled spin pairs develop power-law correlations. The corresponding phase diagram contains an intermediate or crossover regime, which has power-law spin-z correlations resulting from contributions of the rare events. We discuss the physical picture for the numerical observations in this regime, where various distribution functions are distinctly different from results deep in the ergodic and MBL phases for finite-size systems. Our results may provide new insights for understanding the phase transition in such systems.

  19. Effects of livestock species and stocking density on accretion rates in grazed salt marshes

    Science.gov (United States)

    Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

    2015-01-01

    Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive accelerated SLR depends on sufficient deposition of sediments which add to vertical marsh accretion. Accretion rate is influenced by a number of factors, and livestock grazing was recently included. Livestock grazing is assumed to reduce accretion rates in two ways: (a) directly by increasing soil compaction through trampling, and (b) indirectly by affecting the vegetation structure, which may lower the sediment deposition. For four years, we studied the impact of two livestock species (horse and cattle) at two stocking densities (0.5 and 1.0 animal ha-1) on accretion in a large-scale grazing experiment using sedimentation plates. We found lower cumulative accretion rates in high stocking densities, probably because more animals cause more compaction and create a lower canopy. Furthermore, a trend towards lower accretion rates in horse-compared to cattle-grazed treatments was found, most likely because (1) horses are more active and thus cause more compaction, and (2) herbage intake by horses is higher than by cattle, which causes a higher biomass removal and shorter canopy. During summer periods, negative accretion rates were found. When the grazing and non-grazing seasons were separated, the impact of grazing differed among years. In summer, we only found an effect of different treatments if soil moisture (precipitation) was relatively low. In winter, a sufficiently high inundation frequency was necessary to create differences between grazing treatments. We conclude that stocking densities, and to a certain extent also livestock species, affect accretion rates in salt marshes. Both stocking densities and livestock species should thus be taken into account in management

  20. Intermolecular Interaction Potentials of CH4-Ne Complex Calculated with Local Density Approximation Methods

    Institute of Scientific and Technical Information of China (English)

    BAI Yu-Lin; CHENG Xiao-Hong; CHEN Xiang-Rong; YANG Xiang-Dong; ZHU Jun

    2004-01-01

    @@ The intermolecular interactions potentials for two configurations of CH4-Ne complex are calculated with local density approximation methods in the frame of density functional theory. It is found that the calculated potentials have two minima when the distance between the carbon atom of CH4 and the Ne atom takes R = 5.80 a.u.and 6.20a. u. for both the two configurations. For the edge configuration, the corresponding depth of the potential is 0.0669536 eV and 0.0671416 eV. For the face configuration, the corresponding depth of the potential is 0.0737956 eV and 0.0645506 eV. The global minimum occurs at R = 5.80 a.u. for the face configuration with a depth of the potential 0.0737956 eV. The depths of our calculation are in better agreement with the experimental data than the quantum chemical calculation approach, while the position of minimum potential for our calculation is underestimated.

  1. Mineral Nutritional Yield and Nutrient Density of Locally Adapted Wheat Genotypes under Organic Production

    Directory of Open Access Journals (Sweden)

    Sergio Daniel Moreira-Ascarrunz

    2016-12-01

    Full Text Available The aim of the present investigation was to investigate the nutritional yield, nutrient density, stability, and adaptability of organically produced wheat for sustainable and nutritional high value food production. This study evaluated the nutritional yield of four minerals (Fe, Zn, Cu, and Mg in 19 wheat genotypes, selected as being locally adapted under organic agriculture conditions. The new metric of nutritional yield was calculated for each genotype and they were evaluated for stability using the Additive Main effects and Multiplicative Interaction (AMMI stability analysis and for genotypic value, stability, and adaptability using the Best Linear Unbiased Prediction (BLUP procedure. The results indicated that there were genotypes suitable for production under organic agriculture conditions with satisfactory yields (>4000 kg·ha−1. Furthermore, these genotypes showed high nutritional yield and nutrient density for the four minerals studied. Additionally, since these genotypes were stable and adaptable over three environmentally different years, they were designated “balanced genotypes” for the four minerals and for the aforementioned characteristics. Selection and breeding of such “balanced genotypes” may offer an alternative to producing nutritious food under low-input agriculture conditions. Furthermore, the type of evaluation presented here may also be of interest for implementation in research conducted in developing countries, following the objectives of producing enough nutrients for a growing population.

  2. Cs diffusion in local Taiwan laterite with different solution concentration, pH and packing density

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T.-H. [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Li, M.-H. [Institute of Hydrological Sciences, National Central University, Jungli 320, Taiwan (China); Teng, S.-P. [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 300, Taiwan (China)], E-mail: spteng@ess.nthu.edu.tw

    2008-09-15

    In this work we used an 'in-diffusion' method to study the effects of pH, solution concentration and packing density on Cs diffusion by packing local Taiwan laterite (LTL) into modified capillary columns with 5 mm diameter. These packed columns were first pre-equilibrated with synthetic groundwater (GW) for 3 weeks. The diffusion experiments were then carried out at ambient condition for 2 weeks. Our experimental results showed that the Cs diffusion profile fits Fick's second law very well in given experimental conditions, indicating the validity of modified capillary column method. Generally speaking, Cs diffusion in LTL decreases as the pH increases and as Cs concentration decreases. The apparent diffusion coefficient (D{sub a}) increases from 5.52x10{sup -12} (10{sup -7} M) to 2.18x10{sup -11} (10{sup -3} M) m{sup 2}/s, while the effective diffusion coefficient (D{sub e}) shows slight variation as the Cs concentration changes. Both the derived D{sub a} and D{sub e} values decrease as the pH increases, implying that the diffusion mechanisms of Cs nuclide in alkaline and acid environment are different. In addition, our results show that Cs diffusion is unaffected by the given packing density, indicating the interlaminary space is not the major determinant of Cs adsorption and diffusion in LTL.

  3. Heliconia acuminata reproductive success is independent of local floral density O sucesso reprodutivo de Heliconia acuminata é independente da densidade floral local

    Directory of Open Access Journals (Sweden)

    Emilio M. Bruna

    2004-09-01

    Full Text Available Reproductive plants in tropical forests are patchily distributed, with some in large aggregations of reproductive consepecifics while others are relatively isolated. This variation in floral density is hypothesized to have a major effect on plant reproductive success, since individuals in higher density neighborhoods can attract more or higher quality pollinators. We experimentally tested this hypothesis with populations of the understory herb Heliconia acuminata in central Amazonia. We created replicated plots in which reproductive plant density spanned the range of naturally occurring floral neighborhood size, then measured three surrogates of plant fitness in focal plants in each array. There was no significant difference between any of the three floral neighborhood treatments in total seed production, fruit set, or the number of seeds produced per fruit. Pollinator visitation rates to plants in all treatments were extremely low, with many plants not visited at all during the observation period. This could be because H. acuminata's hummingbird pollinators are unable to find the widely scattered reproductive plants, however this hypothesis appears unlikely. Instead, natural flowering plant densities may simply be below the threshold value at which neighborhood effects become important, even in "high-density" aggregations. Nutrient limitation, selective fruit abortion, and reproduction via male rather than female function may also be playing a role. We argue the absence of neighborhood effects may be a general phenomenon in central Amazonian forests, though additional experiments with other plant-pollinator systems are needed to determine the extent to which this hypothesis is supported.Plantas reprodutivas em florestas tropicas são distribuidas em manchas, com algumas em grandes agregações coespecíficas e outras relativamente isoladas. A hipótese é que esta variação na densidade de flores em um local tem um grande efeito no sucesso

  4. Depression of belowground respiration rates at simulated high moose population densities in boreal forests.

    Science.gov (United States)

    Persson, Inga-Lill; Nilsson, Mats B; Pastor, John; Eriksson, Tobias; Bergström, Roger; Danell, Kjell

    2009-10-01

    Large herbivores can affect the carbon cycle in boreal forests by changing productivity and plant species composition, which in turn could ultimately alter litter production, nutrient cycling, and the partitioning between aboveground and belowground allocation of carbon. Here we experimentally tested how moose (Alces alces) at different simulated population densities affected belowground respiration rates (estimated as CO2 flux) in young boreal forest stands situated along a site productivity gradient. At high simulated population density, moose browsing considerably depressed belowground respiration rates (24-56% below that of no-moose controls) except during June, where the difference only was 10%. Moose browsing depressed belowground respiration the most on low-productivity sites. Soil moisture and temperature did not affect respiration rates. Impact of moose on belowground respiration was closely linked to litter production and followed Michaelis-Menten dynamics. The main mechanism by which moose decrease belowground respiration rates is likely their effect on photosynthetic biomass (especially decreased productivity of deciduous trees) and total litter production. An increased productivity of deciduous trees along the site productivity gradient causes an unequal effect of moose along the same gradient. The rapid growth of deciduous trees may offer higher resilience against negative effects of moose browsing on litter production and photosynthate allocation to roots.

  5. Kinetic energy density and agglomerate abrasion rate during blending of agglomerates into powders.

    Science.gov (United States)

    Willemsz, Tofan A; Hooijmaijers, Ricardo; Rubingh, Carina M; Tran, Thanh N; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees

    2012-01-23

    Problems related to the blending of a cohesive powder with a free flowing bulk powder are frequently encountered in the pharmaceutical industry. The cohesive powder often forms lumps or agglomerates which are not dispersed during the mixing process and are therefore detrimental to blend uniformity. Achieving sufficient blend uniformity requires that the blending conditions are able to break up agglomerates, which is often an abrasion process. This study was based on the assumption that the abrasion rate of agglomerates determines the required blending time. It is shown that the kinetic energy density of the moving powder bed is a relevant parameter which correlates with the abrasion rate of agglomerates. However, aspects related to the strength of agglomerates should also be considered. For this reason the Stokes abrasion number (St(Abr)) has been defined. This parameter describes the ratio between the kinetic energy density of the moving powder bed and the work of fracture of the agglomerate. The St(Abr) number is shown to predict the abrasion potential of agglomerates in the dry-mixing process. It appeared possible to include effects of filler particle size and impeller rotational rate into this concept. A clear relationship between abrasion rate of agglomerates and the value of St(Abr) was demonstrated. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. The star-formation rate density from z = 0-6

    CERN Document Server

    Rowan-Robinson, Michael; Wang, Lingyu; Farrah, Duncan; Clements, David; Gruppioni, Carlotta; Marchetti, Lucia; Rigopoulou, Dimitra; Varcari, Mattia

    2016-01-01

    We use 3035 Herschel-SPIRE 500$\\mu$m sources from 20.3 sq deg of sky in the HerMES Lockman, ES1 and XMM-LSS areas to estimate the star-formation rate density at z = 1-6. 500 mu sources are associated first with 350 and 250 mu sources, and then with Spitzer 24 mu sources from the SWIRE photometric redshift catalogue. The infrared and submillimetre data are fitted with a set of radiative-transfer templates corresponding to cirrus (quiescent) and starburst galaxies. Lensing candidates are removed via a set of colour-colour and colour-redshift constraints. Star-formation rates are found to extend from < 1 to 20,000 Mo/yr. Such high values were also seen in the all-sky IRAS Faint Source Survey. Star-formation rate functions are derived in a series of redshift bins from 0-6, combined with earlier far-infrared estimates, where available, and fitted with a Saunders et al (1990) functional form. The star-formation-rate density as a function of redshift is derived and compared with other estimates. There is reasonab...

  7. Independent constraints on local non-Gaussianity from the peculiar velocity and density fields

    CERN Document Server

    Ma, Yin-Zhe; Scott, Douglas

    2013-01-01

    Primordial, non-Gaussian perturbations can generate scale-dependent bias in the galaxy distribution. This in turn will modify correlations between galaxy positions and peculiar velocities at late times, since peculiar velocities reflect the underlying matter distribution, whereas galaxies are a biased tracer of the same. We study this effect, and show that non-Gaussianity can be constrained by comparing the observed peculiar velocity field to a model velocity field reconstructed from the galaxy density field assuming linear bias. The amplitude of the spatial correlations in the residual map obtained after subtracting one velocity field from the other is directly proportional to the strength of the primordial non-Gaussianity. We construct the corresponding likelihood function use it to constrain the amplitude of the linear flow $\\beta$ and the amplitude of local non-Gaussianity $f^{NL}_{local}$. Applying our method to two observational data sets, the Type-Ia supernovae (A1SN) and Spiral Field \\textit{I}-band (...

  8. Global and local reactivity of simple substituted nitrenes and phosphinidenes within the spin-polarized density functional theory framework

    Science.gov (United States)

    Rincón, Elizabeth; Pérez, Patricia; Chamorro, Eduardo

    2007-11-01

    The local reactivity proclivities in a series of simple substituted nitrenes (N-X) and phosphinidenes (P-X) have been explored for the lowest-lying singlet and triplet electronic states within the framework of spin-polarized density functional theory (SP-DFT). Linear correlations have been found between both the global and local philicities for spin polarization and the vertical singlet-triplet energy gaps. The accumulation and depletion of the electron or spin density can be directly related to the electronegativity of the substituent atoms. The local analysis has been achieved on the basis of a recent implementation of condensed-to-site SP-DFT Fukui functions.

  9. Probing the peak of the star formation rate density with the extragalactic background light

    CERN Document Server

    Raue, Martin

    2012-01-01

    The extragalactic background light (EBL), i.e., the diffuse meta-galactic photon field in the ultraviolet to infrared, is dominated by the emission from stars in galaxies. It is, therefore, intimately connected with the integrated star formation rate density (SFRD). In this paper, the SFRD is constrained using recent limits on the EBL density derived from observations of distant sources of high and very-high energy gamma-rays. The stellar EBL contribution is modeled utilizing simple stellar population spectra including dust attenuation and emission. A wide range of values for the different model parameters (SFRD(z), metallicity, dust absorption) is investigated and their impact on the resulting EBL is studied. The calculated EBL densities are compared with the specific EBL density limits and constraints on the SFRD are derived. For the fiducial model, adopting a Chabrier initial mass function (IMF), the SFRD is constrained to ~< 0.1 M_solar yr^-1 Mpc^-3 and < 0.2 M_solar yr^-1 Mpc^-3 for a redshift of z...

  10. Effect of Different Stocking Densities on Survival Rates of Nile Tilapia Fingerlings Transported in Plastic Bags.

    Directory of Open Access Journals (Sweden)

    Adam Ibrahim AM

    2015-10-01

    Full Text Available Fish farmers in Sudan obtain their seed stocks mainly not from their farms and as such rely heavily on good packing conditions covering sometimes 8–12 hours transportation time to maximize fish survival and quality the study here required main objective to identified the optimum loading for the success during transporting. closed oxygenated plastic bag which was carried three densities for each one with tow replicate for every treatment for the lower loading is 75 fingerlings /l the medium is, 100 fingerlings and last density is the larger one 140 fingerlings the duration factors was 10 hours, 11 hours and 18 hours. The fingerlings was sex reversed, their size is (5g ± 0.5. The collecting data analyze used SPSS computer software version- 16.0. Analysis result shown the factor of density in the tow treatments (75 fingerlings + 100 fingerlings was the best according to the survivor rate depending to type of the periods parameter. 10 hour=94% and 11 hours = 92% and here was N.S otherwise the comparative between those and the density 140 was high significant. Variation between loading and durations is NS at P<0.05, so the conclusions is found the optimum loading during transporting period was 100/l/18 (hundred fish per litter in 18 hours period according to analysis details.

  11. Computation of local exchange coefficients in strongly interacting one-dimensional few-body systems: local density approximation and exact results

    DEFF Research Database (Denmark)

    Marchukov, O. V.; Eriksen, E. H.; Midtgaard, J. M.

    2016-01-01

    -trivial geometric factors that depend solely on the geometry of the confinement through the single-particle eigenstates of the external potential. To obtain accurate effective Hamiltonians to describe such systems one needs to be able to compute these geometric factors with high precision which is difficult due...... to the computational complexity of the high-dimensional integrals involved. An approach using the local density approximation would therefore be a most welcome approximation due to its simplicity. Here we assess the accuracy of the local density approximation by going beyond the simple harmonic oscillator that has...

  12. A Novel Multi-Focus Image Fusion Method Based on Stochastic Coordinate Coding and Local Density Peaks Clustering

    Directory of Open Access Journals (Sweden)

    Zhiqin Zhu

    2016-11-01

    Full Text Available The multi-focus image fusion method is used in image processing to generate all-focus images that have large depth of field (DOF based on original multi-focus images. Different approaches have been used in the spatial and transform domain to fuse multi-focus images. As one of the most popular image processing methods, dictionary-learning-based spare representation achieves great performance in multi-focus image fusion. Most of the existing dictionary-learning-based multi-focus image fusion methods directly use the whole source images for dictionary learning. However, it incurs a high error rate and high computation cost in dictionary learning process by using the whole source images. This paper proposes a novel stochastic coordinate coding-based image fusion framework integrated with local density peaks. The proposed multi-focus image fusion method consists of three steps. First, source images are split into small image patches, then the split image patches are classified into a few groups by local density peaks clustering. Next, the grouped image patches are used for sub-dictionary learning by stochastic coordinate coding. The trained sub-dictionaries are combined into a dictionary for sparse representation. Finally, the simultaneous orthogonal matching pursuit (SOMP algorithm is used to carry out sparse representation. After the three steps, the obtained sparse coefficients are fused following the max L1-norm rule. The fused coefficients are inversely transformed to an image by using the learned dictionary. The results and analyses of comparison experiments demonstrate that fused images of the proposed method have higher qualities than existing state-of-the-art methods.

  13. Rating the effectiveness of local tobacco policies for reducing youth smoking.

    Science.gov (United States)

    Lipperman-Kreda, Sharon; Friend, Karen B; Grube, Joel W

    2014-04-01

    Important questions remain regarding the effectiveness of local tobacco policies for preventing and reducing youth tobacco use and the relative importance of these policies. The aims of this paper are to: (1) compare policy effectiveness ratings provided by researchers and tobacco prevention specialists for individual local tobacco policies, and (2) develop and describe a systematic approach to score communities for locally-implemented tobacco policies. We reviewed municipal codes of 50 California communities to identify local tobacco regulations in five sub-domains. We then developed an instrument to rate the effectiveness of these policies and administered it to an expert panel of 40 tobacco researchers and specialists. We compared mean policy effectiveness ratings obtained from researchers and prevention specialists and used it to score the 50 communities. High inter-rater reliabilities obtained for each sub-domain indicated substantial agreement among the raters about relative policy effectiveness. Results showed that, although researchers and prevention specialists differed on the mean levels of policy ratings, their relative rank ordering of the effectiveness of policy sub-domains were very similar. While both researchers and prevention specialists viewed local outdoor clean air policies as least effective in preventing and reducing youth cigarette smoking, they rated tobacco sales policies and advertising and promotion as more effective than the other policies. Moreover, we found high correlations between community scores generated from researchers' and prevention specialists' ratings. This approach can be used to inform research on local policies and prevention efforts and help bridge the gap between research and practice.

  14. Flow rate of particles through apertures obtained from self-similar density and velocity profiles

    OpenAIRE

    2012-01-01

    ‘‘Beverloo’s law’’ is considered as the standard expression to estimate the flow rate of particles through apertures. This relation was obtained by simple dimensional analysis and includes empirical parameters whose physical meaning is poorly justified. In this Letter, we study the density and velocity profiles in the flow of particles through an aperture. We find that, for the whole range of apertures studied, both profiles are self-similar. Hence, by means of the functionality obtained for the...

  15. Tactical UAV Localization Using Coordinated Monopulse Trackers with Low Rate Feedback

    Directory of Open Access Journals (Sweden)

    Chan-ho An

    2013-07-01

    Full Text Available To run a tactical unmanned aerial vehicle (UAV, efficient information transmission schemes, such as beamforming, are preferred due to the limit of the payload. Therefore, beam tracking and localization algorithms are considered to be one of the key technologies. In this paper, we propose a coordinated UAV localization algorithm for a tactical scenario where the ground receivers are connected with wireless limited lower rate backhaul and are closely spaced. By applying the αβ filter to the conventional scheme, we first show that the localization performance can be improved significantly. We also propose an efficient localization algorithm for a system with low rate limited feedback. Using numerical simulations, we show that the proposed scheme can improve the localization performance while reducing the feedback over conventional scheme.

  16. Estimation of population firing rates and current source densities from laminar electrode recordings.

    Science.gov (United States)

    Pettersen, Klas H; Hagen, Espen; Einevoll, Gaute T

    2008-06-01

    This model study investigates the validity of methods used to interpret linear (laminar) multielectrode recordings. In computer experiments extracellular potentials from a synaptically activated population of about 1,000 pyramidal neurons are calculated using biologically realistic compartmental neuron models combined with electrostatic forward modeling. The somas of the pyramidal neurons are located in a 0.4 mm high and wide columnar cylinder, mimicking a stimulus-evoked layer-5 population in a neocortical column. Current-source density (CSD) analysis of the low-frequency part (estimates of the true underlying CSD. The high-frequency part (>750 Hz) of the potentials (multi-unit activity, MUA) is found to scale approximately as the population firing rate to the power 3/4 and to give excellent estimates of the underlying population firing rate for trial-averaged data. The MUA signal is found to decay much more sharply outside the columnar populations than the LFP.

  17. Flow Rate of Particles through Apertures Obtained from Self-Similar Density and Velocity Profiles

    Science.gov (United States)

    Janda, Alvaro; Zuriguel, Iker; Maza, Diego

    2012-06-01

    “Beverloo’s law” is considered as the standard expression to estimate the flow rate of particles through apertures. This relation was obtained by simple dimensional analysis and includes empirical parameters whose physical meaning is poorly justified. In this Letter, we study the density and velocity profiles in the flow of particles through an aperture. We find that, for the whole range of apertures studied, both profiles are self-similar. Hence, by means of the functionality obtained for them the mass flow rate is calculated. The comparison of this expression with the Beverloo’s one reveals some differences which are crucial to understanding the mechanism that governs the flow of particles through orifices.

  18. Distribution of energy storage rate in area of strain localization during tension of austenitic steel

    Science.gov (United States)

    Oliferuk, W.; Maj, M.; Zembrzycki, K.

    2015-01-01

    The present work is devoted to experimental determination of the energy storage rate in the area of strain localization. The experimental procedure involves two complementary techniques: i.e. infrared thermography (IRT) and visible light imaging. The results of experiments have shown that during the evolution of plastic strain localization the energy storage rate in some areas of the deformed specimen drops to zero. To interpret the decrease of the energy storage rate in terms of micro-mechanisms, microstructural observations using electron back scattered diffraction (EBSC) were performed.

  19. A posteriori error estimator for adaptive local basis functions to solve Kohn-Sham density functional theory

    CERN Document Server

    Kaye, Jason; Yang, Chao

    2014-01-01

    Kohn-Sham density functional theory is one of the most widely used electronic structure theories. The recently developed adaptive local basis functions form an accurate and systematically improvable basis set for solving Kohn-Sham density functional theory using discontinuous Galerkin methods, requiring a small number of basis functions per atom. In this paper we develop residual-based a posteriori error estimates for the adaptive local basis approach, which can be used to guide non-uniform basis refinement for highly inhomogeneous systems such as surfaces and large molecules. The adaptive local basis functions are non-polynomial basis functions, and standard a posteriori error estimates for $hp$-refinement using polynomial basis functions do not directly apply. We generalize the error estimates for $hp$-refinement to non-polynomial basis functions. We demonstrate the practical use of the a posteriori error estimator in performing three-dimensional Kohn-Sham density functional theory calculations for quasi-2D...

  20. Local density of optical states in the band gap of a finite photonic crysta

    CERN Document Server

    Yeganegi, Elahe; Mosk, Allard P; Vos, Willem L

    2014-01-01

    We study the local density of states (LDOS) in a finite photonic crystal, in particular in the frequency range of the band gap. We propose a new point of view on the band gap, which we consider to be the result of vacuum fluctuations in free space that tunnel in the forbidden range in the crystal. As a result, we arrive at a model for the LDOS that is in two major items modified compared to the well-known expression for infinite crystals. Firstly, we modify the Dirac delta functions to become Lorentzians with a width set by the crystal size. Secondly, building on characterization of the fields versus frequency and position we calculated the fields in the band gap. We start from the fields at the band edges, interpolated in space and position, and incorporating the exponential damping in the band gap. We compare our proposed model to exact calculations in one dimension using the transfer matrix method and find very good agreement. Notably, we find that in finite crystals, the LDOS depends on frequency, on posi...

  1. Characteristics of local photonic state density in an infinite two-dimensional photonic crystal

    Institute of Scientific and Technical Information of China (English)

    Zhou Yun-Song; Wang Xue-Hua; Gu Ben-Yuan; Wang Fu-He

    2005-01-01

    The local density of photonic states (LDPS) of an infinite two-dimensional (2D) photonic crystal (PC) composed of rotated square-pillars in a 2D square lattice is calculated in terms of the plane-wave expansion method in a combination with the point group theory. The calculation results show that the LDPS strongly depends on the spatial positions.The variations of the LDPS as functions of the radial coordinate and frequency exhibit "mountain chain" structures with sharp peaks. The LDPS with large value spans a finite area and falls abruptly down to small value at the position corresponding to the interfaces between two different refractive index materials. The larger/lower LDPS occurs inward the lower/larger dielectric-constant medium. This feature can be well interpreted by the continuity of electricdisplacement vector at the interface. In the frequency range of the pseudo-PBG (photonic band gap), the LDPS keeps very low value over the whole Wiger-Seitz cell. It indicates that the spontaneous emission in 2D PCs cannot be prohibited completely, but it can be inhibited intensively when the resonate frequency falls into the pseudo-PBG.

  2. Local density approximation results for bond length alternation in the infinite polyyne chain

    Science.gov (United States)

    Bylaska, Eric; Weare, John

    1998-03-01

    Calculations for large even numbered carbon ring molecules and band structure calculations for the infinite polyyne chain within the local density approximation are reported. We studied the alternation of bond lengths in this system as a function of size. Particular focus is on alternation in the infinite system. For intermediate and large sized Cn rings with n satisfying n=4N (doubly-antiaromatic rings) there is a substantial first order Jahn-Teller distortion which decreases for large N. On the other hand, for Cn rings satisfying n=4N+2 (doubly-aromatic rings) the second order Jahn-Teller distortion does not produce bond length alternation even by the large C_42 ring. The persistance of aromatic behavior in the very large carbon rings manifests itself in the band structure calculations by making the amount of bond length alternation predicted for the infinite polyyne chain extremely sensitive to the numerical treatment of the Brillouin zone. We have shown that the infinite polyyne has a finite amount of bond length alternation but the condensation energy is very small.

  3. Effective mass density based topology optimization of locally resonant acoustic metamaterials for bandgap maximization

    Science.gov (United States)

    Yang, Xiong Wei; Lee, Joong Seok; Kim, Yoon Young

    2016-11-01

    Because effective material properties are essential concepts in the analyses of wave phenomena in metamaterials, they may also be utilized in the optimal design of metamaterials. In this work, we propose a topology optimization method directly using the Effective Mass Density (EMD) concept to maximize the first bandgaps of two-dimensional solid Locally Resonant Acoustic Metamaterials (LRAMs). When the first bandgap is characterized by the negative EMD, the bandgap maximization can be formulated efficiently as a topology optimization problem to broaden the frequency zone of the negative EMD values. In this work, EMD is calculated by considering the macroscopic isotropy of LRAMs in the long wavelength limit. To facilitate the analytical sensitivity analysis, we propose an elaborate calculation scheme of EMD. A sensitivity averaging technique is also suggested to guarantee the macroscopically isotropic behavior of the LRAMs. In the present study, the coating layer interfacing the core and the matrix of a ternary LRAM is chosen as the design region because it significantly influences the bandgap. By considering several numerical examples, the validity of this method is verified, and the effects of the mass constraint ratios on the optimized results are also investigated.

  4. RKKY interaction and local density of states for a triangular triple quantum dot system

    Science.gov (United States)

    Xiong, Yong-Chen; Wang, Wei-Zhong; Luo, Shi-Jun; Yang, Jun-Tao; Huang, Hai-Ming

    2016-02-01

    By means of the numerical renormalization group technique, we study the local density of states (LDOS) for a triangular triple quantum dot system, with two dots connected in parallel to the conduction leads. We find the location of the Ruderman-Kittel-Kasuya-Yosida (RKKY) peak identified in the LDOS could be illustrated as JRKKY = aΓ2 / U +bt22 / U, with U being the on-site Coulomb repulsion, Γ the dot-lead coupling, and t2 the hopping between the connected dots and the side dot. When the hopping between two connected dots t1 turns on, the spectrum weight of the RKKY peaks decreases due to the competition between the direct and the RKKY interactions. As t1 increases beyond a critical point t1c, two connected dots form a spin singlet, and decouple from both the side dot and the conduction leads, thus the Kondo and RKKY peaks could not be found. For t1 1 ≥t1 c, it drops to zero.

  5. Spontaneous-emission control by local density of states of photonic crystal cavity

    Institute of Scientific and Technical Information of China (English)

    Jiang Bin; Zhang Ye-Jin; Zhou Wen-Jun; Chen Wei; Liu An-Jin; Zheng Wan-Hua

    2011-01-01

    The local density of states (LDOS) of two-dimensional square lattice photonic crystal (PhC) defect cavity is studied. The results show that the LDOS in the centre is greatly reduced, while the LDOS at the point off the centre (for example, at the point (0.3a, 0.4a), where a is the lattice constant) is extremely enhanced. Further, the disordered radii are introduced to imitate the real devices fabricated in our experiment, and then we study the LDOS of PhC cavity with configurations of different disordered radii. The results show that in the disordered cavity, the LDOS in the centre is still greatly reduced, while the LDOS at the point (0.3a, 0.4a) is still extremely enhanced. It shows that the LDOS analysis is useful. When a laser is designed on the basis of the square lattice PhC rod cavity, in order to enhance the spontaneous emission, the active materials should not be inserted in the centre of the cavity, but located at positions off the centre. So LDOS method gives a guide to design the positions of the active materials (quantum dots) in the lasers.

  6. 2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lin, L., E-mail: lianglin@ucla.edu; Ding, W. X.; Brower, D. L. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States)

    2014-11-15

    Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved.

  7. 2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements.

    Science.gov (United States)

    Lin, L; Ding, W X; Brower, D L

    2014-11-01

    Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved.

  8. Calibrating the Human Mutation Rate via Ancestral Recombination Density in Diploid Genomes.

    Directory of Open Access Journals (Sweden)

    Mark Lipson

    2015-11-01

    Full Text Available The human mutation rate is an essential parameter for studying the evolution of our species, interpreting present-day genetic variation, and understanding the incidence of genetic disease. Nevertheless, our current estimates of the rate are uncertain. Most notably, recent approaches based on counting de novo mutations in family pedigrees have yielded significantly smaller values than classical methods based on sequence divergence. Here, we propose a new method that uses the fine-scale human recombination map to calibrate the rate of accumulation of mutations. By comparing local heterozygosity levels in diploid genomes to the genetic distance scale over which these levels change, we are able to estimate a long-term mutation rate averaged over hundreds or thousands of generations. We infer a rate of 1.61 ± 0.13 × 10-8 mutations per base per generation, which falls in between phylogenetic and pedigree-based estimates, and we suggest possible mechanisms to reconcile our estimate with previous studies. Our results support intermediate-age divergences among human populations and between humans and other great apes.

  9. Bond length and local energy density property connections for non-transition-metal oxide-bonded interactions.

    Science.gov (United States)

    Gibbs, G V; Spackman, M A; Jayatilaka, D; Rosso, K M; Cox, D F

    2006-11-01

    For a variety of molecules and earth materials, the theoretical local kinetic energy density, G(r(c)), increases and the local potential energy density, V(r(c)), decreases as the M-O bond lengths (M = first- and second-row metal atoms bonded to O) decrease and the electron density, rho(r(c)), accumulates at the bond critical points, r(c). Despite the claim that the local kinetic energy density per electronic charge, G(r(c))/rho(r(c)), classifies bonded interactions as shared interactions when less than unity and closed-shell when greater, the ratio was found to increase from 0.5 to 2.5 au as the local electronic energy density, H(r(c)) = G(r(c)) + V(r(c)), decreases and becomes progressively more negative. The ratio appears to be a measure of the character of a given M-O bonded interaction, the greater the ratio, the larger the value of rho(r(c)), the smaller the coordination number of the M atom and the more shared the bonded interaction. H(r(c))/rho(r(c)) versus G(r(c))/rho(r(c)) scatter diagrams categorize the M-O bonded interactions into domains with the local electronic energy density per electron charge, H(r(c))/rho(r(c)), tending to decrease as the electronegativity differences for the bonded pairs of atoms decrease. The values of G(r(c)) and V(r(c)), estimated with a gradient-corrected electron gas theory expression and the local virial theorem, are in good agreement with theoretical values, particularly for the bonded interactions involving second-row M atoms. The agreement is poorer for shared C-O and N-O bonded interactions.

  10. Experimental study of proton rate density in a spherical inertial electrostatic confinement fusion device

    Science.gov (United States)

    Gu, Yibin

    The concept of spherical inertial-electrostatic confinement (SIEC) is to focus and accelerate ions and electrons radially inward into the center of a negatively biased, highly transparent spherical grid to create a space-charge double-potential well (a negative-potential well nested inside a positive-potential well) which confines the high-energy ions in the dense central core region such that appreciable nuclear fusion reactions are obtained. This experimental work has focused on creating the double-potential well at high perveance (I/V3/2) where there is a significant charge build-up in the center, and on proving the existence of the well from its characteristic radial proton rate density profile. Based on the spatial measurement of the D-D fusion protons by using a capillary proton collimator and the unfolding of this data, this work has been directed to evaluate the radial proton rate density profiles to explore the evolution of potential-well structure in the current and voltage (perveance) range where the double well is expected. Under the optimized operating conditions admitted by using the Star mode to improve focusing to 1.6× ballistic limit and double-grid setup to reduce the ion radial energy spread to 0.34 mA/kV3/2. As the perveance increases, the feature of the double well becomes prominent. At 1.38 mA/kV3/2 (80 mA and 15 kV), the maximum negative potential well depth obtained from the measured proton rate density was calculated, using a beam-background fusion and charge-exchange model, to be ~22-27% of the applied voltage. Also, during the progress of this dissertation, two valuable SIEC derivatives-an SIEC wavelength tunable x- ray source (SIEC-TX) and an IEC linear neutron source device (C-device)-have been developed. The SIEC-TX generates x-rays by electron-electron interactions at relativistic velocity at the sphere center when the electrons are accelerated and focused by a spherical grid. The wavelength of the emitted x-rays shifts as the grid

  11. The Effects of Population Density on Juvenile Growth Rate in White-Tailed Deer

    Science.gov (United States)

    Barr, Brannon; Wolverton, Steve

    2014-10-01

    Animal body size is driven by habitat quality, food availability, and nutrition. Adult size can relate to birth weight, to length of the ontogenetic growth period, and/or to the rate of growth. Data requirements are high for studying these growth mechanisms, but large datasets exist for some game species. In North America, large harvest datasets exist for white-tailed deer ( Odocoileus virginianus), but such data are collected under a variety of conditions and are generally dismissed for ecological research beyond local population and habitat management. We contend that such data are useful for studying the ecology of white-tailed deer growth and body size when analyzed at ordinal scale. In this paper, we test the response of growth rate to food availability by fitting a logarithmic equation that estimates growth rate only to harvest data from Fort Hood, Texas, and track changes in growth rate over time. Results of this ordinal scale model are compared to previously published models that include additional parameters, such as birth weight and adult weight. It is shown that body size responds to food availability by variation in growth rate. Models that estimate multiple parameters may not work with harvest data because they are prone to error, which renders estimates from complex models too variable to detect interannual changes in growth rate that this ordinal scale model captures. This model can be applied to harvest data, from which inferences about factors that influence animal growth and body size (e.g., habitat quality and nutritional availability) can be drawn.

  12. The relation between atomic gas and star formation rate densities in faint irregular galaxies

    CERN Document Server

    Roychowdhury, Sambit; Kaisin, Serafim S; Karachentsev, Igor D

    2014-01-01

    We use data for faint (M_B > -14.5) dwarf irregular galaxies drawn from the FIGGS survey to study the correlation between the atomic gas density (Sigma_gas,atomic) and star formation rate (Sigma_SFR) in the galaxies. The estimated gas phase metallicity of our sample galaxies is Z ~ 0.1 Z_sun. Understanding star formation in such molecule poor gas is of particular importance since it is likely to be of direct relevance to simulations of early galaxy formation. For about 20% (9/43) of our sample galaxies, we find that the HI distribution is significantly disturbed, with little correspondence between the optical and HI distributions. We exclude these galaxies from the comparison. We also exclude galaxies with very low star formation rates, for which stochastic effects make it difficult to estimate the true star formation rates. For the remaining galaxies we compute the Sigma_gas,atomic and Sigma_SFR averaged over the entire star forming disk of the galaxy. For these galaxies we find a nearly linear relation betw...

  13. In Situ Measurement of Local Hydrogen Production Rate by Bubble-Evolved Recording

    Directory of Open Access Journals (Sweden)

    Xiaowei Hu

    2013-01-01

    Full Text Available Hydrogen visibly bubbles during photocatalytic water splitting under illumination with above-bandgap radiation, which provides a direct measurement of local gas-evolving reaction rate. In this paper, optical microscopy of superfield depth was used for recording the hydrogen bubble growth on Cd0.5Zn0.5S photocatalyst in reaction liquid and illuminated with purple light. By analyzing change of hydrogen bubble size as a function of time, we understood that hydrogen bubble growth experienced two periods, which were inertia effect dominated period and diffusion effect dominated period, respectively. The tendency of hydrogen bubble growth was similar to that of the gas bubble in boiling, while the difference in bubble diameter and growth time magnitude was great. Meanwhile, we obtained the local hydrogen production rate on photocatalyst active site by measuring hydrogen bubble growth variation characteristics. This method makes it possible to confirm local actual hydrogen evolution rate quantitatively during photocatalytic water splitting.

  14. The local energy production rates of GRB photons and of UHECRs

    CERN Document Server

    Waxman, Eli

    2010-01-01

    In a recent analysis it was found that the local (z=0) rate at which gamma-ray bursts (GRBs) produce energy in 1 MeV photons, Q_GRB(z=0), is 300 times lower than the local energy production rate in ultra-high energy cosmic-rays. This may appear to be in contradiction with earlier results, according to which Q_GRB(z=0) is similar to the local energy production rate in >10^{19} eV cosmic-rays, Q_{10EeV}(z=0). This short (1 page) note identifies the origin of the apparent discrepancy and shows that Q_GRB(z=0) Q_{10EeV}(z=0) holds.

  15. Milagro Limits and HAWC Sensitivity for the Rate-Density of Evaporating Primordial Black Holes

    CERN Document Server

    Abdo, A A; Alfaro, R; Allen, B T; Alvarez, C; Álvarez, J D; Arceo, R; Arteaga-Velázquez, J C; Aune, T; Solares, H A Ayala; Barber, A S; Baughman, B M; Bautista-Elivar, N; Gonzalez, J Becerra; Belmont, E; BenZvi, S Y; Berley, D; Rosales, M Bonilla; Braun, J; Caballero-Lopez, R A; Caballero-Mora, K S; Carramiñana, A; Castillo, M; Chen, C; Christopher, G E; Cotti, U; Cotzomi, J; de la Fuente, E; De León, C; DeYoung, T; Hernandez, R Diaz; Diaz-Cruz, L; Díaz-Vélez, J C; Dingus, B L; DuVernois, M A; Ellsworth, R W; Fiorino, D W; Fraija, N; Galindo, A; Garfias, F; González, M M; Goodman, J A; Grabski, V; Gussert, M; Hampel-Arias, Z; Harding, J P; Hays, E; Hoffman, C M; Hui, C M; Hüntemeyer, P; Imran, A; Iriarte, A; Karn, P; Kieda, D; Kolterman, B E; Kunde, G J; Lara, A; Lauer, R J; Lee, W H; Lennarz, D; Vargas, H León; Linares, E C; Linnemann, J T; Longo, M; Luna-GarcIa, R; MacGibbon, J H; Marinelli, A; Marinelli, S S; Martinez, H; Martinez, O; Martínez-Castro, J; Matthews, J A J; McEnery, J; Torres, E Mendoza; Mincer, A I; Miranda-Romagnoli, P; Moreno, E; Morgan, T; Mostafá, M; Nellen, L; Nemethy, P; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T; Patricelli, B; Pelayo, R; Pérez-Pérez, E G; Pretz, J; Rivière, C; Rosa-González, D; Ruiz-Velasco, E; Ryan, J; Salazar, H; Salesa, F; Sandoval, A; Parkinson, P M Saz; Schneider, M; Shoup, A; Silich, S; Sinnis, G; Smith, A J; Stump, D; Woodle, K Sparks; Springer, R W; Taboada, I; Toale, P A; Tollefson, K; Torres, I; Ukwatta, T N; Vasileiou, V; Villaseñor, L; Walker, G P; Weisgarber, T; Westerhoff, S; Williams, D A; Wisher, I G; Wood, J; Yodh, G B; Younk, P W; Zaborov, D; Zepeda, A; Zhou, H

    2014-01-01

    Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and can emit all species of fundamental particles thermally. PBHs with initial masses of ~5.0 x 10^14 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV - TeV energy range, making them candidate Gamma-ray Burst (GRB) progenitors. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma-rays, the Milagro observatory is well suited for a direct search of PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a...

  16. Milagro Limits and HAWC Sensitivity for the Rate-Density of Evaporating Primordial Black Holes

    Science.gov (United States)

    Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Alvarez, J. D.; Arceo, R.; Arteaga-Velazquez, J. C.; Aune, T.; Ayala Solares, H. A.; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Becerra Gonzalez, J.; Belmont, E.; BenZvi, S. Y.; Berley, D.; Rosales, M. Bonilla; Braun, J.; Hays, E.

    2014-01-01

    Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of approx.5.0 x 10(exp 14) g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.

  17. Milagro limits and HAWC sensitivity for the rate-density of evaporating Primordial Black Holes

    Science.gov (United States)

    Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Aune, T.; Ayala Solares, H. A.; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Becerra Gonzalez, J.; Belmont, E.; BenZvi, S. Y.; Berley, D.; Bonilla Rosales, M.; Braun, J.; Caballero-Lopez, R. A.; Caballero-Mora, K. S.; Carramiñana, A.; Castillo, M.; Christopher, G. E.; Cotti, U.; Cotzomi, J.; de la Fuente, E.; De León, C.; DeYoung, T.; Diaz Hernandez, R.; Diaz-Cruz, L.; Díaz-Vélez, J. C.; Dingus, B. L.; DuVernois, M. A.; Ellsworth, R. W.; Fiorino, D. W.; Fraija, N.; Galindo, A.; Garfias, F.; González, M. M.; Goodman, J. A.; Grabski, V.; Gussert, M.; Hampel-Arias, Z.; Harding, J. P.; Hays, E.; Hoffman, C. M.; Hui, C. M.; Hüntemeyer, P.; Imran, A.; Iriarte, A.; Karn, P.; Kieda, D.; Kolterman, B. E.; Kunde, G. J.; Lara, A.; Lauer, R. J.; Lee, W. H.; Lennarz, D.; León Vargas, H.; Linares, E. C.; Linnemann, J. T.; Longo, M.; Luna-GarcIa, R.; MacGibbon, J. H.; Marinelli, A.; Marinelli, S. S.; Martinez, H.; Martinez, O.; Martínez-Castro, J.; Matthews, J. A. J.; McEnery, J.; Mendoza Torres, E.; Mincer, A. I.; Miranda-Romagnoli, P.; Moreno, E.; Morgan, T.; Mostafá, M.; Nellen, L.; Nemethy, P.; Newbold, M.; Noriega-Papaqui, R.; Oceguera-Becerra, T.; Patricelli, B.; Pelayo, R.; Pérez-Pérez, E. G.; Pretz, J.; Rivière, C.; Rosa-González, D.; Ruiz-Velasco, E.; Ryan, J.; Salazar, H.; Salesa, F.; Sandoval, A.; Saz Parkinson, P. M.; Schneider, M.; Silich, S.; Sinnis, G.; Smith, A. J.; Stump, D.; Sparks Woodle, K.; Springer, R. W.; Taboada, I.; Toale, P. A.; Tollefson, K.; Torres, I.; Ukwatta, T. N.; Vasileiou, V.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Williams, D. A.; Wisher, I. G.; Wood, J.; Yodh, G. B.; Younk, P. W.; Zaborov, D.; Zepeda, A.; Zhou, H.

    2015-04-01

    Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ∼5.0 × 1014 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.

  18. Milagro Limits and HAWC Sensitivity for the Rate-Density of Evaporating Primordial Black Holes

    Science.gov (United States)

    Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Alvarez, J. D.; Arceo, R.; Arteaga-Velazquez, J. C.; Aune, T.; Ayala Solares, H. A.; hide

    2014-01-01

    Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of approx.5.0 x 10(exp 14) g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.

  19. Evaluate the Word Error Rate of Binary Block Codes with Square Radius Probability Density Function

    CERN Document Server

    Chen, Xiaogang; Gu, Jian; Yang, Hongkui

    2007-01-01

    The word error rate (WER) of soft-decision-decoded binary block codes rarely has closed-form. Bounding techniques are widely used to evaluate the performance of maximum-likelihood decoding algorithm. But the existing bounds are not tight enough especially for low signal-to-noise ratios and become looser when a suboptimum decoding algorithm is used. This paper proposes a new concept named square radius probability density function (SR-PDF) of decision region to evaluate the WER. Based on the SR-PDF, The WER of binary block codes can be calculated precisely for ML and suboptimum decoders. Furthermore, for a long binary block code, SR-PDF can be approximated by Gamma distribution with only two parameters that can be measured easily. Using this property, two closed-form approximative expressions are proposed which are very close to the simulation results of the WER of interesting.

  20. The Space Density of Extended Ultraviolet (XUV) Disks in the Local Universe and Implications for Gas Accretion on to Galaxies

    CERN Document Server

    Lemonias, Jenna J; Thilker, David; Wyder, Ted K; Martin, D Christopher; Seibert, Mark; Treyer, Marie A; Bianchi, Luciana; Heckman, Timothy M; Madore, Barry F; Rich, R Michael

    2011-01-01

    We present results of the first unbiased search for extended UV (XUV)-disk galaxies undertaken to determine the space density of such galaxies. Our sample contains 561 local (0.001 1.5 x 10^4 s) and SDSS DR7 footprints. We explore modifications to the standard classification scheme for our sample that includes both disk- and bulge-dominated galaxies. Visual classification of each galaxy in the sample reveals an XUV-disk frequency of up to 20% for the most nearby portion of our sample. On average over the entire sample (out to z=0.05) the frequency ranges from a hard limit of 4% to 14%. The GALEX imaging allows us to detect XUV-disks beyond 100 Mpc. The XUV regions around XUV-disk galaxies are consistently bluer than the main bodies. We find a surprisingly high frequency of XUV emission around luminous red (NUV-r > 5) and green valley (3 1.5-4.2 x 10^-3 Mpc^-3. Using the XUV emission as an indicator of recent gas accretion, we estimate that the cold gas accretion rate onto these galaxies is > 1.7-4.6 x 10^-3...

  1. The influence of gaming expenditure on crime rates in South Australia: a local area empirical investigation.

    Science.gov (United States)

    Wheeler, Sarah Ann; Round, David K; Sarre, Rick; O'Neil, Michael

    2008-03-01

    Although there has been much speculation about the possible links between gambling and crime rates, relevant quantitative evidence has been practically non-existent in Australia to date. This paper reports the results of research that utilised a model designed to investigate the potential relationship between electronic gaming machine expenditures and property (income-generating) crime rates reported to police in local areas in South Australia in 2002-2003. The research found that the higher the expenditures on gaming machines in a particular local area per adult, the higher the income-generating crime rate in that area. No such relationship was found between gaming machine expenditure and non-income-generating crime rates. However, further research is required before any policy-relevant conclusions can be drawn.

  2. Theoretical Electron Density Distributions for Fe- and Cu-Sulfide Earth Materials: A Connection between Bond Length, Bond Critical Point Properties, Local Energy Densities, and Bonded Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Gibbs, Gerald V.; Cox, David F.; Rosso, Kevin M.; Ross, Nancy L.; Downs, R. T.; Spackman, M. A.

    2007-03-01

    Bond critical point and local energy density properties together with net atomic charges were calculated for theoretical electron density distributions, F(r), generated for a variety of Fe and Cu metal-sulfide materials with high- and low-spin Fe atoms in octahedral coordination and high-spin Fe atoms in tetrahedral coordination. The electron density, F(rc), the Laplacian, 32F(rc), the local kinetic energy, G(rc), and the oxidation state of Fe increase as the local potential energy density, V(rc), the Fe-S bond lengths, and the coordination numbers of the Fe atoms decrease. The properties of the bonded interactions for the octahedrally coordinated low-spin Fe atoms for pyrite and marcasite are distinct from those for high-spin Fe atoms for troilite, smythite, and greigite. The Fe-S bond lengths are shorter and the values of F(rc) and 32F(rc) are larger for pyrite and marcasite, indicating that the accumulation and local concentration of F(r) in the internuclear region are greater than those involving the longer, high-spin Fe-S bonded interactions. The net atomic charges and the bonded radii calculated for the Fe and S atoms in pyrite and marcasite are also smaller than those for sulfides with high-spin octahedrally coordinated Fe atoms. Collectively, the Fe-S interactions are indicated to be intermediate in character with the low-spin Fe-S interactions having greater shared character than the highspin interactions. The bond lengths observed for chalcopyrite together with the calculated bond critical point properties are consistent with the formula Cu+Fe3+S2. The bond length is shorter and the F(rc) value is larger for the FeS4 tetrahedron displayed by metastable greigite than those displayed by chalcopyrite and cubanite, consistent with a proposal that the Fe atom in greigite is tetravalent. S-S bond paths exist between each of the surface S atoms of adjacent slabs of FeS6 octahedra comprising the layer sulfide smythite, suggesting that the neutral Fe3S4 slabs are

  3. Milagro Limits and HAWC Sensitivity for the Rate Density of Evaporating Primordial Black Holes

    Science.gov (United States)

    Marinelli, Samuel; HAWC Collaboration; Milagro Collaboration

    2015-04-01

    Primordial black holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all energetically allowed species of fundamental particles thermally. PBHs with initial masses of order 5 . 0 ×1010 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV - TeV energy range. The Milagro high-energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field of view, more than 90% duty cycle, and sensitivity up to 100-TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. A search of five years of Milagro data yielded no detections at 5 σ and set a local (parsec-scale) upper limit of 3 . 6 ×104 PBH bursts/year/pc3. In addition, we will report the sensitivity of the Milagro successor, the High-Altitude Water-Cherenkov (HAWC) observatory, to PBH evaporation events. This work was supported by the National Science Foundation.

  4. Determination of the alpha-tocopherol inhibition rate constant for peroxidation in low-density lipoprotein.

    Science.gov (United States)

    Culbertson, Sean M; Antunes, Fernando; Havrilla, Christine M; Milne, Ginger L; Porter, Ned A

    2002-06-01

    This work reports an estimate of the inhibition rate constant (k(inh)) for alpha-tocopherol (alpha-TOH) in low-density lipoproteins (LDL) based on cholesteryl linoleate hydroperoxide products formed during autoxidation of intact lipoproteins. The ratio of cis,trans/trans,trans product hydroperoxides was determined during the consumption of the antioxidant. For a reasonable determination of k(inh) in LDL, the pro-oxidant behavior of alpha-TOH was minimized by oxidizing LDL with an unsymmetrical amphiphilic azo initiator which significantly reduces phase-transfer mediated pro-oxidant effects of alpha-TOH. This initiator delivers a more constant flux of initiator radicals into LDL lipid regions and permits determination of alpha-TOH k(inh) in LDL. Development of a tocopherol-mediated peroxidation (TMP) model and analysis of cholesteryl linoleate hydroperoxide cis,trans/trans,trans product ratios provided an estimated value for the inhibition rate constant of alpha-TOH in a lipoprotein of k(inh) = 5.9 +/- 0.5 x 10(5) M(-)(1) s(-)(1)

  5. Bayesian random local clocks, or one rate to rule them all

    Directory of Open Access Journals (Sweden)

    Drummond Alexei J

    2010-08-01

    Full Text Available Abstract Background Relaxed molecular clock models allow divergence time dating and "relaxed phylogenetic" inference, in which a time tree is estimated in the face of unequal rates across lineages. We present a new method for relaxing the assumption of a strict molecular clock using Markov chain Monte Carlo to implement Bayesian modeling averaging over random local molecular clocks. The new method approaches the problem of rate variation among lineages by proposing a series of local molecular clocks, each extending over a subregion of the full phylogeny. Each branch in a phylogeny (subtending a clade is a possible location for a change of rate from one local clock to a new one. Thus, including both the global molecular clock and the unconstrained model results, there are a total of 22n-2 possible rate models available for averaging with 1, 2, ..., 2n - 2 different rate categories. Results We propose an efficient method to sample this model space while simultaneously estimating the phylogeny. The new method conveniently allows a direct test of the strict molecular clock, in which one rate rules them all, against a large array of alternative local molecular clock models. We illustrate the method's utility on three example data sets involving mammal, primate and influenza evolution. Finally, we explore methods to visualize the complex posterior distribution that results from inference under such models. Conclusions The examples suggest that large sequence datasets may only require a small number of local molecular clocks to reconcile their branch lengths with a time scale. All of the analyses described here are implemented in the open access software package BEAST 1.5.4 (http://beast-mcmc.googlecode.com/.

  6. Curve fitting of the corporate recovery rates: the comparison of Beta distribution estimation and kernel density estimation.

    Directory of Open Access Journals (Sweden)

    Rongda Chen

    Full Text Available Recovery rate is essential to the estimation of the portfolio's loss and economic capital. Neglecting the randomness of the distribution of recovery rate may underestimate the risk. The study introduces two kinds of models of distribution, Beta distribution estimation and kernel density distribution estimation, to simulate the distribution of recovery rates of corporate loans and bonds. As is known, models based on Beta distribution are common in daily usage, such as CreditMetrics by J.P. Morgan, Portfolio Manager by KMV and Losscalc by Moody's. However, it has a fatal defect that it can't fit the bimodal or multimodal distributions such as recovery rates of corporate loans and bonds as Moody's new data show. In order to overcome this flaw, the kernel density estimation is introduced and we compare the simulation results by histogram, Beta distribution estimation and kernel density estimation to reach the conclusion that the Gaussian kernel density distribution really better imitates the distribution of the bimodal or multimodal data samples of corporate loans and bonds. Finally, a Chi-square test of the Gaussian kernel density estimation proves that it can fit the curve of recovery rates of loans and bonds. So using the kernel density distribution to precisely delineate the bimodal recovery rates of bonds is optimal in credit risk management.

  7. Information Transmission and Anderson Localization in two-dimensional networks of firing-rate neurons

    Science.gov (United States)

    Natale, Joseph; Hentschel, George

    Firing-rate networks offer a coarse model of signal propagation in the brain. Here we analyze sparse, 2D planar firing-rate networks with no synapses beyond a certain cutoff distance. Additionally, we impose Dale's Principle to ensure that each neuron makes only or inhibitory outgoing connections. Using spectral methods, we find that the number of neurons participating in excitations of the network becomes insignificant whenever the connectivity cutoff is tuned to a value near or below the average interneuron separation. Further, neural activations exceeding a certain threshold stay confined to a small region of space. This behavior is an instance of Anderson localization, a disorder-induced phase transition by which an information channel is rendered unable to transmit signals. We discuss several potential implications of localization for both local and long-range computation in the brain. This work was supported in part by Grants JSMF/ 220020321 and NSF/IOS/1208126.

  8. Community Colleges and Labor Market Conditions: How Does Enrollment Demand Change Relative to Local Unemployment Rates?

    Science.gov (United States)

    Hillman, Nicholas W.; Orians, Erica Lee

    2013-01-01

    This study uses fixed-effects panel data techniques to estimate the elasticity of community college enrollment demand relative to local unemployment rates. The findings suggest that community college enrollment demand is counter-cyclical to changes in the labor market, as enrollments rise during periods of weak economic conditions. Using national…

  9. Strain localization band width evolution by electronic speckle pattern interferometry strain rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)], E-mail: bruno.guelorget@utt.fr; Francois, Manuel; Montay, Guillaume [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2009-04-15

    In this paper, electronic speckle pattern interferometry strain rate measurements are used to quantify the width of the strain localization band, which occurs when a sheet specimen is submitted to tension. It is shown that the width of this band decreases with increasing strain. Just before fracture, this measured width is about five times wider than the shear band and the initial sheet thickness.

  10. Path Integrals for Electronic Densities, Reactivity Indices, and Localization Functions in Quantum Systems

    Directory of Open Access Journals (Sweden)

    Mihai V. Putz

    2009-11-01

    Full Text Available The density matrix theory, the ancestor of density functional theory, provides the immediate framework for Path Integral (PI development, allowing the canonical density be extended for the many-electronic systems through the density functional closure relationship. Yet, the use of path integral formalism for electronic density prescription presents several advantages: assures the inner quantum mechanical description of the system by parameterized paths; averages the quantum fluctuations; behaves as the propagator for time-space evolution of quantum information; resembles Schrödinger equation; allows quantum statistical description of the system through partition function computing. In this framework, four levels of path integral formalism were presented: the Feynman quantum mechanical, the semiclassical, the Feynman-Kleinert effective classical, and the Fokker-Planck non-equilibrium ones. In each case the density matrix or/and the canonical density were rigorously defined and presented. The practical specializations for quantum free and harmonic motions, for statistical high and low temperature limits, the smearing justification for the Bohr’s quantum stability postulate with the paradigmatic Hydrogen atomic excursion, along the quantum chemical calculation of semiclassical electronegativity and hardness, of chemical action and Mulliken electronegativity, as well as by the Markovian generalizations of Becke-Edgecombe electronic focalization functions – all advocate for the reliability of assuming PI formalism of quantum mechanics as a versatile one, suited for analytically and/or computationally modeling of a variety of fundamental physical and chemical reactivity concepts characterizing the (density driving many-electronic systems.

  11. The effect of turbidity and prey fish density on consumption rates of piscivorous Eurasian perch Perca fluviatilis

    DEFF Research Database (Denmark)

    Jacobsen, Lene; Berg, Søren; Baktoft, Henrik

    2014-01-01

    piscivorous Eurasian perch Perca fluviatilis L. This was done in outdoor mesocosm (16 m2) experiments with clear water and two levels of turbidity (25 and 105 NTU) and two prey fish densities [3.1 and 12.5 roach Rutilus rutilus (L.) individuals m–2]. Perch consumption rates were affected by visibility less...... than expected, while they were highly affected by increased prey fish density. Perch responded to high prey density in all visibility conditions, indicating that prey density is more crucial for consumption than visibility in turbid lakes...

  12. On the inconsistency between cosmic stellar mass density and star formation rate up to $z\\sim8$

    CERN Document Server

    Yu, H

    2016-01-01

    In this paper, we test the discrepancy between the stellar mass density and instantaneous star formation rate in redshift range $06$), the derived star formation history is consistent with the observations. This is the first time to test the discrepancy between the observed stellar mass density and instantaneous star formation rate up to very high redshift $z\\approx8$ using the Markov chain monte carlo method and a varying recycling factor. Several possible reasons for this discrepancy are discussed, such as underestimation of stellar mass density, initial mass function and cosmic metallicity evolution.

  13. The role of landscape features and density dependence in growth and fledging rates of Piping Plovers in North Dakota, USA

    Science.gov (United States)

    Anteau, Michael J.; Wiltermuth, Mark T.; Sherfy, Mark H.; Shaffer, Terry L.; Pearse, Aaron T.

    2014-01-01

    For species with precocial young, survival from hatching to fledging is a key factor influencing recruitment. Furthermore, growth rates of precocial chicks are an indicator of forage quality and habitat suitability of brood-rearing areas. We examined how growth and fledging rates of Piping Plover (Charadrius melodus) chicks were influenced by landscape features, such as hatchling density (hatchlings per hectare of remotely sensed habitat [H ha-1]), island vs. mainland, and wind fetch (exposure to waves) at 2-km segments (n ¼ 15) of Lake Sakakawea, North Dakota, during 2007–2008. Hatchling growth was comparable with published estimates for other habitats. Models for fledging rate (fledged young per segment) assuming density dependence had more support (wi ¼ 96%) than those assuming density independence (wi ¼ 4%). Density-dependent processes appeared to influence fledging rate only at densities .5 H ha-1, which occurred in 19% of the segments we sampled. When areas with densities .5 H ha-1 were excluded, density-dependence and density-independence models were equally supported (wi ¼ 52% and 48%, respectively). Fledging rate declined as the wind fetch of a segment increased. Fledging rate on mainland shorelines was 4.3 times greater than that on islands. Previous work has indicated that plovers prefer islands for nesting, but our results suggest that this preference is not optimal and could lead to an ecological trap for chicks. While other researchers have found nesting-habitat requirements to be gravelly areas on exposed beaches without fine-grain substrates, our results suggest that chicks fledge at lower rates in these habitats. Thus, breeding plovers likely require complexes of these nesting habitats along with protected areas with fine, nutrient-rich substrate for foraging by hatchlings.

  14. Effect of various dietary nutrient density on the growth performance of local male ducks and their crosse

    Directory of Open Access Journals (Sweden)

    I.A.K Bintang

    1998-12-01

    Full Text Available Three hundred day-old male ducklings were allocated randomly into 12 treatment combinations in 3 x 4 factorial design . Three levels of dietary density ration i.e : Low(12% /2,000 kcal, medium (16%/2,500 kcal and high (20%/3,000 kcal and 2 breeds of local ducks Tegal (TT and Mojosari (MM and their crossbreds (Tegal x Mojosari (TM and Mojosari x Tegal (MT were applied. Each treatment combination consisted of5 replicates, each of 5 birds. The experiment was carried out for 8 weeks and measurements were weekly feed intake, body weight, weight and/or percentage of carcass, internal organs and abdominal fat. Results indicated that no significant interaction was detected between dietary nutrient density and the breeds of ducks on all parameters measured . Breeds of duck, as well as their crosses did not affect growth performance and other parameters . On the other hand, nutrient density influenced growth performance significantly, except for percentage of carcass and internal organs . In general, feed intake, body weight gain, feed efficiency, carcass weight and abdominal fat of ducks fed low density ration were significantly lower than those fed medium density, which were also lower than those fed high nutrient density diet . Weghtand length of intestine and kidney weight, of ducks fed low density diet however, were higher than the two other treatments .

  15. Local smoke-free public policies, quitline call rate, and smoking status in Kentucky.

    Science.gov (United States)

    Fernander, Anita F; Rayens, Mary Kay; Adkins, Sarah; Hahn, Ellen J

    2014-01-01

    The study investigated the relationships among local smoke-free public policies, county-level quitline call rate, and adult smoking status. A retrospective cross-sectional examination of demographic characteristics, smoking status of Kentuckians, and data from the Kentucky Tobacco Quitline were used to investigate the relationship of local smoke-free ordinances or Board of Health regulations together with county-level quitline use rates and population-level adult smoking status. One hundred and four Kentucky counties. The sample was comprised of 14,184 Kentucky participants with complete demographic information collected from the 2009-2010 Behavioral Risk Factor Surveillance System (BRFSS). Individual-level demographics and smoking status from the BRFSS; county-level urban/rural status; quitline rates; and smoke-free policy status. Given the hierarchical structure of the dataset, with BRFSS respondents nested within county, multilevel modeling was used to determine the predictors of smoking status. For every 1-unit increase in the county-level call rate the likelihood of current smoking status decreased by 9%. Compared to those living in communities without a policy, those in communities with a smoke-free public policy were 18% less likely to be current smokers. Limitations include quitline call rate as the sole indicator of cessation demand, as well as the cross-sectional design. Communities with smoke-free policies and higher rates of quitline use have lower rates of adult smoking.

  16. Gamma distribution model describes maturational curves for delta wave amplitude, cortical metabolic rate and synaptic density.

    Science.gov (United States)

    Feinberg, I; Thode, H C; Chugani, H T; March, J D

    1990-01-23

    We analyzed the available ontogenetic data (birth to 30 years of age) for: amplitude of delta EEG (DA) waves during sleep; cortical metabolic rate (CMR) measured with positron emission tomography; and synaptic density (SD) in frontal cortex. Each is at the adult level at birth, increases to about twice this level by 3 years of age, and then gradually falls back to the adult level over the next two decades. Statistical analyses revealed that individual gamma distribution models fit each data set as well as did the best ad hoc polynomial. A test of whether a single gamma distribution model could describe all three data sets gave good results for DA and CMR but the fit was unsatisfactory for SD. However, because so few data were available for SD, this test was not conclusive. We proposed the following model to account for these changes. First, cortical neurons are stimulated by birth to enter a proliferative state (PS) that creates many connections. Next, as a result of interactions in the PS, neurons are triggered into a transient organizational state (OS) in which they make enduring connections. The OS has a finite duration (minutes to years), and is characterized by high rates of information-processing and metabolism. Levels of CMR, SD and DA, therefore, are proportional to the number of neurons in the OS at any time. Thus, the cortex after birth duplicates, over a vastly greater time scale, the overproduction and regression of neural elements that occurs repeatedly in embryonic development. Finally, we discussed the implications of post-natal brain changes for normal and abnormal brain function. Mental disorders that have their onset after puberty (notably schizophrenia and manic-depressive psychoses) might be caused by errors in these late maturational processes. In addition to age of onset, this neurodevelopmental hypothesis might explain several other puzzling features of these subtle disorders.

  17. 5 CFR 532.205 - The use of Federal, State, and local minimum wage requirements in determining prevailing rates.

    Science.gov (United States)

    2010-01-01

    ... minimum wage requirements in determining prevailing rates. 532.205 Section 532.205 Administrative... Determinations § 532.205 The use of Federal, State, and local minimum wage requirements in determining prevailing... amended, or (2) The highest State or local minimum wage rate in the local wage area which is applicable to...

  18. Effects of stocking density on growth performance, carcass yield, and immune status of a local chicken breed.

    Science.gov (United States)

    Tong, H B; Lu, J; Zou, J M; Wang, Q; Shi, S R

    2012-03-01

    An experiment was conducted to evaluate the effect of stocking density on growth performance, carcass yield, and immune status of a local chicken breed. In total, 840 one-day-old male Suqin yellow chickens were placed into 4-m(2) cages in groups of 50 (low), 70 (medium), or 90 (high) birds. Each treatment was represented by 4 replicates (cages). The cages measured 2.84 × 1.42 m; half of the area of the cage (2 m(2)) was used from 1 to 28 d and the whole cage was used from 29 to 42 d. Stocking densities were 25, 35, and 45 birds/m(2) from 1 to 28 d and 12.5, 17.5, and 22.5 birds/m(2) from 29 to 42 d (low, medium, and high, respectively). Final production (live bird mass after fasting) per unit area was 14.46, 19.46, and 24.23 kg/m(2), respectively, at 42 d of age. Several immune parameters were evaluated, and the growth performance, carcass yield, and meat quality were determined. Body weight at 28 and 42 d of age was significantly reduced as the stocking density increased (P 0.05). The thigh yield of chickens in the medium-density group improved significantly (P 0.05) by the stocking density, but pH values increased slightly as density increased. No significant difference was noted in the immunological parameters, but the blood total protein and potassium were significantly affected by stocking density (P < 0.05). The findings of this study suggest that increasing the stocking density advantageously affected feed/gain and decreased the final BW, whereas no evidence was found that stocking density caused changes in any of the measured immune parameters.

  19. Local Lyapunov exponents sublimiting growth rates of linear random differential equations

    CERN Document Server

    Siegert, Wolfgang

    2009-01-01

    Establishing a new concept of local Lyapunov exponents the author brings together two separate theories, namely Lyapunov exponents and the theory of large deviations. Specifically, a linear differential system is considered which is controlled by a stochastic process that during a suitable noise-intensity-dependent time is trapped near one of its so-called metastable states. The local Lyapunov exponent is then introduced as the exponential growth rate of the linear system on this time scale. Unlike classical Lyapunov exponents, which involve a limit as time increases to infinity in a fixed system, here the system itself changes as the noise intensity converges, too.

  20. An Analysis of Statewide Adoption Rates of Building Energy Code by Local Jurisdictions

    Energy Technology Data Exchange (ETDEWEB)

    Cort, Katherine A.; Butner, Ryan S.

    2012-12-31

    The purpose of this study is to generally inform the U.S. Department of Energy’s Building Energy Codes Program of the local, effective energy code adoption rate for a sample set of 21 states, some which have adopted statewide codes and some that have not. Information related to the residential energy code adoption process and status at the local jurisdiction was examined for each of the states. Energy code status information was gathered for approximately 2,800 jurisdictions, which effectively covered approximately 80 percent of the new residential building construction in the 21 states included in the study.

  1. On the sensitivity of dimensional stability of high density polyethylene on heating rate

    Directory of Open Access Journals (Sweden)

    2007-02-01

    Full Text Available Although high density polyethylene (HDPE is one of the most widely used industrial polymers, its application compared to its potential has been limited because of its low dimensional stability particularly at high temperature. Dilatometry test is considered as a method for examining thermal dimensional stability (TDS of the material. In spite of the importance of simulation of TDS of HDPE during dilatometry test it has not been paid attention by other investigators. Thus the main goal of this research is concentrated on simulation of TDS of HDPE. Also it has been tried to validate the simulation results and practical experiments. For this purpose the standard dilatometry test was done on the HDPE speci­mens. Secant coefficient of linear thermal expansion was computed from the test. Then by considering boundary conditions and material properties, dilatometry test has been simulated at different heating rates and the thermal strain versus temper­ature was calculated. The results showed that the simulation results and practical experiments were very close together.

  2. On the global and local nuclear stopping in mass asymmetric nuclear collisions using density-dependent symmetry energy

    Science.gov (United States)

    Amandeep, K.; Suneel, K.

    2017-09-01

    The present theoretical calculations have been performed within the framework of IQMD model to study a particular set of mass symmetric and asymmetric reactions (keeping total mass fixed) over a wide range of incident energies and colliding geometries. It has been observed that global as well as local nuclear stopping is influenced by the mass asymmetry of the reaction strongly. Influence of density-dependent symmetry energy has been observed in local nuclear stopping. Global stopping decreases with the increase in colliding geometry. Effect of colliding geometry on nuclear stopping is more at higher energies.

  3. Obtaining Highly Excited Eigenstates of Many-Body Localized Hamiltonians by the Density Matrix Renormalization Group Approach.

    Science.gov (United States)

    Khemani, Vedika; Pollmann, Frank; Sondhi, S L

    2016-06-17

    The eigenstates of many-body localized (MBL) Hamiltonians exhibit low entanglement. We adapt the highly successful density-matrix renormalization group method, which is usually used to find modestly entangled ground states of local Hamiltonians, to find individual highly excited eigenstates of MBL Hamiltonians. The adaptation builds on the distinctive spatial structure of such eigenstates. We benchmark our method against the well-studied random field Heisenberg model in one dimension. At moderate to large disorder, the method successfully obtains excited eigenstates with high accuracy, thereby enabling a study of MBL systems at much larger system sizes than those accessible to exact-diagonalization methods.

  4. Localization of the Proton Pump of Corn Coleoptile Microsomal Membranes by Density Gradient Centrifugation 1

    Science.gov (United States)

    Mandala, Suzanne; Mettler, Irvin J.; Taiz, Lincoln

    1982-01-01

    Previous studies characterizing an ATP-dependent proton pump in microsomal membrane vesicles of corn coleoptiles led to the conclusion that the proton pump was neither mitochondrial nor plasma membrane in origin (Mettler, Mandala, Taiz 1982 Plant Physiol 70: 1738-1742). To facilitate positive identification of the vesicles, corn coleoptile microsomal membranes were fractionated on linear sucrose and dextran gradients, with ATP-dependent [14C]methylamine uptake as a probe for proton pumping. On sucrose gradients, proton pumping activity exhibited a density of 1.11 grams/cubic centimeter and was coincident with the endoplasmic reticulum (ER). In the presence of high magnesium, the ER shifted to a heavier density, while proton pumping activity showed no density shift. On linear dextran gradients, proton pumping activity peaked at a lighter density than the ER. The proton pump appears to be electrogenic since both [14C]SCN− uptake and 36Cl− uptake activities coincided with [14C] methylamine uptake on dextran gradients. On the basis of density and transport properties, we conclude that the proton pumping vesicles are probably derived from the tonoplast. Nigericin-stimulated ATPase activity showed a broad distribution which did not coincide with any one membrane marker. PMID:16662755

  5. Field-effect modulation of the local density of optical states in a reflectarray metasurface (Conference Presentation)

    Science.gov (United States)

    Kafaie Shirmanesh, Ghazaleh; Sokhoyan, Ruzan; Han, Seunghoon; Atwater, Harry A.

    2016-09-01

    During recent years, advances in the design of arrays of subwavelength optical elements with special electromagnetic properties have enabled quasi two-dimensional structures that control and manipulate electromagnetic phase, amplitude and polarization. Active control of the response of metasurfaces is possible using transparent conducting oxides such as Indium Tin Oxide (ITO) as a tunable active material [1]. Changing the complex permittivity of ITO by applying a voltage yields modulation of reflected wave phase and amplitude. To achieve this, we designed subwavelength antenna arrays consisting of a gold back reflector and gold fishbone antennas. Planar dielectric layers containing a gate tunable layer of ITO are sandwiched between the back reflector and the antenna. The obtained structure shows resonance around 1.5 µm. As a result, based on the 1.54 µm photoluminescence emission of Er doped Al2O3 films, we embedded trivalent erbium ions as quantum emitters inside an alumina host within the metasurface in order to enhance the local density of optical states (LDOS). Simulations indicate the designed structure shows a significant LDOS enhancement (of order of hundreds). By applying a bias between the antenna and the ITO layer, across an HfO2 gate dielectric, we can control the permittivity of ITO and hence dynamically modulate the decay rate of quantum emitters embedded within the structure. In this way, we can achieve LDOS enhancement modulation of about 325%. 1. Y. W Huang, H. W. H. Lee, R. Sokhoyan, R. Pala, K. Thyagarajan, S. Han, D. P. Tsai, H. A. Atwater, "Gate-tunable conducting oxide metasurfaces". (arXiv:1511.09380).

  6. Galaxy Secular Mass Flow Rate Determination Using the Potential-Density Phase Shift Approach: Application to Six Nearby Spiral Galaxies

    CERN Document Server

    Zhang, Xiaolei

    2016-01-01

    Using the potential-density phase shift approach developed by the present authors in earlier publications, we estimate the magnitude of radial mass accretion/excretion rates across the disks of six nearby spiral galaxies having a range of Hubble types. Our goal is to examine these rates in the context of bulge building and secular morphological evolution along the Hubble sequence. Stellar surface density maps of the sample galaxies are derived from SINGS 3.6um and SDSS i-band images. Corresponding molecular and atomic gas surface densities are derived from published CO(1-0) and HI interferometric observations of the BIMA SONG, THINGS, and VIVA surveys. The mass flow rate calculations utilize a volume-type torque integral to calculate the angular momentum exchange rate between the basic state disk matter and density wave modes. The potential-density phase shift approach yields angular momentum transport rates several times higher than those estimated using the Lynden-Bell and Kalnajs (1972) approach. The curre...

  7. Seizure onset zone localization from ictal high-density EEG in five patients

    OpenAIRE

    Staljanssens, Willeke; Strobbe, Gregor; Van Holen, Roel; Birot, Gwénaël; Michel, Christophe M; Seeck, Margitta; Vandenberghe, Stefaan; Vulliémoz, Serge; van Mierlo, Pieter

    2015-01-01

    Rationale Because epilepsy is a network disease, localization of the exact seizure onset zone (SOZ) is difficult because the epileptic activity can spread to other regions within milliseconds. Functional connectivity metrics quantify how the activity in different brain regions is interrelated. In the past, it has been shown that functional connectivity analysis of ictal intracranial EEG (icEEG) recordings can help with SOZ localization in patients with focal epilepsy (van Mierlo et al., 20...

  8. Localization of ionization-induced trapping in a laser wakefield accelerator using a density down-ramp

    CERN Document Server

    Hansson, M.; Ekerfelt, H.; Aurand, B.; Gallardo Ganzalez, I.; Desforges, F. G.; Davoine, X.; Maitrallain, A.; Reymond, S.; Monot, P.; Persson, A.; Dobosz Dufrénoy S.; Wahlström C-G.; Cros, B.; Lundh, O.

    2016-01-01

    We report on a study on controlled trapping of electrons, by field ionization of nitrogen ions, in laser wakefield accelerators in variable length gas cells. In addition to ionization-induced trapping in the density plateau inside the cells, which results in wide, but stable, electron energy spectra, a regime of ionization-induced trapping localized in the density down-ramp at the exit of the gas cells, is found. The resulting electron energy spectra are peaked, with 10% shot-to-shot fluctuations in peak energy. Ionization-induced trapping of electrons in the density down-ramp is a way to trap and accelerate a large number of electrons, thus improving the efficiency of the laser-driven wakefield acceleration.

  9. The local space density of Sb-Sdm galaxies as function of their scalesize, surface brightness and luminosity

    CERN Document Server

    De Jong, R S; Jong, Roelof S. de; Lacey, Cedric

    2000-01-01

    We investigate the dependence of the local space density of spiral galaxies on luminosity, scalesize and surface brightness. We derive bivariate space density distributions in these quantities from a sample of about 1000 Sb-Sdm spiral galaxies, corrected for selection effects in luminosity and surface brightness. The structural parameters of the galaxies were corrected for internal extinction using a description depending on galaxy surface brightness. We find that the bivariate space density distribution of spiral galaxies in the (luminosity, scalesize)-plane is well described by a Schechter luminosity function in the luminosity dimension and a log-normal scale size distribution at a given luminosity. This parameterization of the scalesize distribution was motivated by a simple model for the formation of disks within dark matter halos, with halos acquiring their angular momenta through tidal torques from neighboring objects, and the disk specific angular momentum being proportional to that of the parent halo....

  10. Coarse-grained models using local-density potentials optimized with the relative entropy: Application to implicit solvation

    Science.gov (United States)

    Sanyal, Tanmoy; Shell, M. Scott

    2016-07-01

    Bottom-up multiscale techniques are frequently used to develop coarse-grained (CG) models for simulations at extended length and time scales but are often limited by a compromise between computational efficiency and accuracy. The conventional approach to CG nonbonded interactions uses pair potentials which, while computationally efficient, can neglect the inherently multibody contributions of the local environment of a site to its energy, due to degrees of freedom that were coarse-grained out. This effect often causes the CG potential to depend strongly on the overall system density, composition, or other properties, which limits its transferability to states other than the one at which it was parameterized. Here, we propose to incorporate multibody effects into CG potentials through additional nonbonded terms, beyond pair interactions, that depend in a mean-field manner on local densities of different atomic species. This approach is analogous to embedded atom and bond-order models that seek to capture multibody electronic effects in metallic systems. We show that the relative entropy coarse-graining framework offers a systematic route to parameterizing such local density potentials. We then characterize this approach in the development of implicit solvation strategies for interactions between model hydrophobes in an aqueous environment.

  11. The impact of sex ratio and economic status on local birth rates.

    Science.gov (United States)

    Chipman, A; Morrison, E

    2013-04-23

    Human mating and reproductive behaviour can vary depending on various mechanisms, including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated with higher birth rates in the poorest areas, whereas the opposite is true for the richest areas. At older ages, a female-biased ratio is associated with higher birth rates in the richest, but not the poorest areas. These patterns suggest that female-female competition encourages poorer women to adopt a fast life-history strategy and give birth early, and richer women to adopt a slow life-history strategy and delay reproduction.

  12. Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)]. E-mail: bruno.guelorget@utt.fr; Francois, Manuel [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Vial-Edwards, Cristian [Departemento de Ingenieria Mecanica y Metalurgica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, 6904411 Santiago (Chile); Montay, Guillaume [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Daniel, Laurent [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Lu, Jian [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2006-01-15

    In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force ({epsilon} {sup t} {approx_equal} 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements.

  13. Thickness and local field effects on energy transfer rate in coupled quantum wells system: Linear regime

    Energy Technology Data Exchange (ETDEWEB)

    Vazifehshenas, T.; Bahrami, B. [Department of Physics, Shahid Beheshti University, G.C., Evin, 1983963113 Tehran (Iran, Islamic Republic of); Salavati-fard, T., E-mail: taha@udel.edu [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

    2012-12-15

    We investigate theoretically the dependence of energy transfer rate in Double-Quantum-Well system on the well thickness by using the balance equation formalism. Also, by including the local field correction in our calculations through the zero- and finite-temperature Hubbard approximations, we study the effect of the short-range interactions on the energy transfer phenomenon. Calculations consider both the static and dynamic screening approximations. Our numerical results predict that the energy transfer rate increases considerably by increasing the layers' thicknesses and by taking into account the short-range interactions, as well.

  14. Salvage high-dose-rate interstitial brachytherapy for locally recurrent rectal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Pellizzon, Antonio Cassio Assis, E-mail: acapellizzon@hcancer.org.br [A.C. Camargo Cancer Center, Sao Paulo, SP (Brazil). Departamento de Radioterapia

    2016-05-15

    For tumors of the lower third of the rectum, the only safe surgical procedure is abdominal-perineal resection. High-dose-rate interstitial brachytherapy is a promising treatment for local recurrence of previously irradiated lower rectal cancer, due to the extremely high concentrated dose delivered to the tumor and the sparing of normal tissue, when compared with a course of external beam radiation therapy. (author)

  15. Salvage high-dose-rate interstitial brachytherapy for locally recurrent rectal cancer*

    Science.gov (United States)

    Pellizzon, Antônio Cássio Assis

    2016-01-01

    For tumors of the lower third of the rectum, the only safe surgical procedure is abdominal-perineal resection. High-dose-rate interstitial brachytherapy is a promising treatment for local recurrence of previously irradiated lower rectal cancer, due to the extremely high concentrated dose delivered to the tumor and the sparing of normal tissue, when compared with a course of external beam radiation therapy. PMID:27403021

  16. In Situ Measurement of Local Hydrogen Production Rate by Bubble-Evolved Recording

    OpenAIRE

    Xiaowei Hu; Liejin Guo; Yechun Wang

    2013-01-01

    Hydrogen visibly bubbles during photocatalytic water splitting under illumination with above-bandgap radiation, which provides a direct measurement of local gas-evolving reaction rate. In this paper, optical microscopy of superfield depth was used for recording the hydrogen bubble growth on Cd0.5Zn0.5S photocatalyst in reaction liquid and illuminated with purple light. By analyzing change of hydrogen bubble size as a function of time, we understood that hydrogen bubble growth experienced two ...

  17. Calculation of the similarity rate between images based on the local minima present Therein

    Directory of Open Access Journals (Sweden)

    K. Hourany

    2016-12-01

    Full Text Available Hourany, K., Benmeddour, F., Moulin, E., Assaad, J. and Zaatar, Y. Calculation of the similarity rate between images based on the local minima present therein. 2016. Lebanese Science Journal, 17(2: 177-192. Image processing is a very vast field that includes both IT and applied mathematics. It is a discipline that studies the improvement and transformations of digital images hence permitting the improvement of the quality of these images and the extraction of information. The comparison of digital images is a paramount issue that has been discussed in several researches because of its various applications especially in the field of control and surveillance such as the Structural Health Monitoring using acoustic waves. The IT support of the images serves especially for comparing them notably in distinguishing differences between these images and quantifying them automatically. In this study we will present an algorithm, allowing us to calculate the similarity rate between images based on the local minima present therein. This algorithm is divided into two main parts. In the first part we will explain how to extract the local minima from an image and in the second part we will show how to calculate the similarity rate between two images.

  18. The Stellar Number Density Distribution in the Local Solar Neighborhood is North-South Asymmetric

    Energy Technology Data Exchange (ETDEWEB)

    Yanny, Brian [Fermilab; Gardner, Susan [Kentucky U.

    2013-10-17

    We study the number density distribution of a sample of K and M dwarf stars, matched North and South of the Galactic plane within a distance of 2 kpc from the sun, using observations from the Ninth Data Release of the Sloan Digital Sky Survey. We determine distances using the photometric parallax method, and in this context systematic effects exist which could potentially impact the determination of the number density profile with height from the Galactic plane --- and ultimately affect a number density North-South asymmetry. They include: (i) the calibration of the various photometric parallax relations, (ii) the ability to separate dwarfs from giants in our sample, (iii) the role of stellar population differences such as age and metallicity, (iv) the ability to determine the offset of the sun from the Galactic plane, and (v) the correction for reddening from dust in the Galactic plane, though our stars are at high Galactic latitudes. We find the various analyzed systematic effects to have a negligible impact on our observed asymmetry, and using a new and larger sample of stars we confirm and refine the earlier discovery of Widrow et al. of a significant Galactic North-South asymmetry in the stellar number density distribution.

  19. Autonomous Bacterial Localization and Gene Expression Based on Nearby Cell Receptor Density

    Science.gov (United States)

    2013-01-22

    Upon detection of B1–5 mM AI-2, these cells express T7 polymerase that amplifies the native lsr operon response by overexpressing DsRed (see...2 for initiating gene expression (lsr operon ). (B) Indicated densities of PCI-15B or HEK293 cells were seeded to wells followed by mouse anti-EGFR

  20. Performance of a local electron density trigger to select extensive air showers at sea level

    Science.gov (United States)

    Abbas, T.; Madani, J.; Ashton, F.

    1985-01-01

    Time coincident voltage pulses in the two closely space (1.6m) plastic scintillators were recorded. Most of the recorded events are expeted to be due to electrons in cosmic ray showers whose core fall at some distance from the detectors. This result is confirmed from a measurement of the frequency distribution of the recorded density ratios of the two scintillators.

  1. Skin blood flow and local temperature independently modify sweat rate during passive heat stress in humans.

    Science.gov (United States)

    Wingo, Jonathan E; Low, David A; Keller, David M; Brothers, R Matthew; Shibasaki, Manabu; Crandall, Craig G

    2010-11-01

    Sweat rate (SR) is reduced in locally cooled skin, which may result from decreased temperature and/or parallel reductions in skin blood flow. The purpose of this study was to test the hypotheses that decreased skin blood flow and decreased local temperature each independently attenuate sweating. In protocols I and II, eight subjects rested supine while wearing a water-perfused suit for the control of whole body skin and internal temperatures. While 34°C water perfused the suit, four microdialysis membranes were placed in posterior forearm skin not covered by the suit to manipulate skin blood flow using vasoactive agents. Each site was instrumented for control of local temperature and measurement of local SR (capacitance hygrometry) and skin blood flow (laser-Doppler flowmetry). In protocol I, two sites received norepinephrine to reduce skin blood flow, while two sites received Ringer solution (control). All sites were maintained at 34°C. In protocol II, all sites received 28 mM sodium nitroprusside to equalize skin blood flow between sites before local cooling to 20°C (2 sites) or maintenance at 34°C (2 sites). In both protocols, individuals were then passively heated to increase core temperature ~1°C. Both decreased skin blood flow and decreased local temperature attenuated the slope of the SR to mean body temperature relationship (2.0 ± 1.2 vs. 1.0 ± 0.7 mg·cm(-2)·min(-1)·°C(-1) for the effect of decreased skin blood flow, P = 0.01; 1.2 ± 0.9 vs. 0.07 ± 0.05 mg·cm(-2)·min(-1)·°C(-1) for the effect of decreased local temperature, P = 0.02). Furthermore, local cooling delayed the onset of sweating (mean body temperature of 37.5 ± 0.4 vs. 37.6 ± 0.4°C, P = 0.03). These data demonstrate that local cooling attenuates sweating by independent effects of decreased skin blood flow and decreased local skin temperature.

  2. Local charge neutrality condition, Fermi level and majority carrier density of a semiconductor with multiple localized multi-level intrinsic/impurity defects

    Institute of Scientific and Technical Information of China (English)

    Ken K. Chin

    2011-01-01

    For semiconductors with localized intrinsic/impurity defects,intentionally doped or unintentionally incorporated,that have multiple transition energy levels among charge states,the general formulation of the local charge neutrality condition is given for the determination of the Fermi level and the majority carrier density.A graphical method is used to illustrate the solution of the problem.Relations among the transition energy levels of the multi-level defect are derived using the graphical method.Numerical examples are given for p-doping of the CdTe thin film used in solar panels and semi-insulating Si to illustrate the relevance and importance of the issues discussed in this work.

  3. Solar Flux Effect on the Reproducibility of Global/Local-Time Variations of Ion Density Structure at Low-Latitude Ionosphere

    Science.gov (United States)

    Su, Shin-Yi

    Longitudinal/seasonal (l/s) variations of ion density structures at the 600-km low-latitude ionosphere observed by ROCSAT-1 between two similar solar activity years of 2000 and 2002 are examined at four different local-time (LT) regions. The gross feature of l/s density structure is almost identical to each other at the four LT regions examined. A complete reproducibility of density structure can be assumed, including the shape of equatorial ionization anomaly (EIA), for identical solar flux input that also implicitly affect other atmospheric components such as the neutral O/N2 ratio and neutral wind variation. The fact that the solar variability effect is thought as the ultimate driver to shape the global ionospheric structure can be confirmed with the reproduction of ROCSAT observations with the simulation results of the TIEGCM model runs using the observed solar flux inputs for various seasons. However, the EIA crestto-valley ratio or no-valley signature in this background density structure can not be used to infer the post-sunset irregularity occurrence rates because the l/s variation of the magnetic declination effect that determines the post-sunset ionospheric conductivity for the ionospheric electrodynamics can not be readily obtained from this ionospheric background structure.

  4. Individual differences in local gray matter density are associated with differences in affective and cognitive empathy.

    Science.gov (United States)

    Eres, Robert; Decety, Jean; Louis, Winnifred R; Molenberghs, Pascal

    2015-08-15

    The understanding of empathy from a neuroscientific perspective has recently developed quickly, with numerous functional MRI studies associating different brain regions with different components of empathy. A recent meta-analysis across 40 fMRI studies revealed that affective empathy is most often associated with increased activity in the insula, whereas cognitive empathy is most often associated with activity in the midcingulate cortex and adjacent dorsomedial prefrontal cortex (MCC/dmPFC). To date, however, it remains unclear whether individual differences in brain morphometry in these regions underlie different dispositions in affective and cognitive empathy. In order to test this hypothesis, voxel-based morphometry (VBM) was used to examine the extent to which gray matter density predicts scores from an established empathy measure (Questionnaire of Cognitive and Affective Empathy; QCAE). One hundred and seventy-six participants completed the QCAE and underwent MRI in order to acquire a high-resolution, three-dimensional T1-weighted structural scans. A factor analysis of the questionnaire scores revealed two distinct factors of empathy, affective and cognitive, which confirmed the validity of the QCAE. VBM results revealed gray matter density differences associated with the distinct components of empathy. Higher scores on affective empathy were associated with greater gray matter density in the insula cortex and higher scores of cognitive empathy were associated with greater gray matter density in the MCC/dmPFC. Taken together, these results provide validation for empathy being a multi-component construct, suggesting that affective and cognitive empathy are differentially represented in brain morphometry as well as providing convergent evidence for empathy being represented by different neural and structural correlates. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Local variability in population structure and density of the protogynous reef herbivore Sparisoma viride

    NARCIS (Netherlands)

    van Rooij, J.M.; Kok, J.P; Videler, J.J

    We compare the (relative) abundance of life phases [juveniles (JU), initial phase (IF) and terminal phase (TP) fish], social categories (territorial and group adults), and fish following alternative mating styles, in three local populations of the protogynous reef herbivore, Sparisoma viride, on the

  6. Local variability in population structure and density of the protogynous reef herbivore Sparisoma viride

    NARCIS (Netherlands)

    van Rooij, J.M.; Kok, J.P; Videler, J.J

    1996-01-01

    We compare the (relative) abundance of life phases [juveniles (JU), initial phase (IF) and terminal phase (TP) fish], social categories (territorial and group adults), and fish following alternative mating styles, in three local populations of the protogynous reef herbivore, Sparisoma viride, on the

  7. Low-Density Parity-Check Codes for High Data Rate Receivers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Low-Density Parity-Check (LDPC) Forward Error Correction (FEC) schemes are excellent tools in optimizing telemetry data integrity within the limited space to ground...

  8. Local extinction and turnover rates at the edge and interior of species' ranges

    Science.gov (United States)

    Doherty, P.F.; Boulinier, T.; Nichols, J.D.

    2003-01-01

    One hypothesis for the maintenance of the edge of a species' range suggests that more central (and abundant) populations are relatively stable and edge populations are less stable with increased local extinction and turnover rates. To date, estimates of such metrics are equivocal due to design and analysis flaws. Apparent increased estimates of extinction and turnover rates at the edge of range, versus the interior, could be a function of decreased detection probabilities alone, and not of a biological process. We estimated extinction and turnover rates for species at the interiors and edges of their ranges using an approach which incorporates potential heterogeneity in species detection probabilities. Extinction rates were higher at the edges (0.17 ' 0.03 [SE]) than in the interiors (0.04 ' 0.01), as was turnover. Without taking the probability of detection into account these differences would be artificially magnified. Knowledge of extinction and turnover rates is essential in furthering our understanding of range dynamics, and in directing conservation efforts. This study further illustrates the practical application of methods proposed recently for estimating extinction rates and other community dynamic parameters.

  9. The luminosity-specific Planetary Nebulae density in Local Group galaxies

    Science.gov (United States)

    Corradi, R. L. M.; Buzzoni, A.; Arnaboldi, M.

    The value of the α ratio, the number of PNe per unit bolometric luminosity in a galaxy, is computed using stellar population synthesis models covering the whole range of Hubble types of galaxies.Model predictions are compared with the PNe counts in the Local Group, which indicate a fairly constant value of α - between 1 and 6 PNe per 10^7 solar luminosities - along the Hubble sequence.

  10. Evaluation of global and local critical current densities in 122-type iron-based superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Pyon, Sunseng, E-mail: pyon@ap.t.u-tokyo.ac.jp; Mine, Akinori; Suwa, Takahiro; Tamegai, Tsuyoshi

    2016-11-15

    Highlights: • (Ba,K)Fe{sub 2}As{sub 2} superconducting pressed tapes are fabricated. • We found an intriguing anisotropy in J{sub c} determined by magnetic measurements, which is related to microcrack structures affecting the local J{sub c}. • Microcrack structures are directly observed by magneto-optical imaging technique. - Abstract: We demonstrate the fabrication of (Ba,K)Fe{sub 2}As{sub 2} superconducting pressed tapes through a powder-in-tube method using uniaxial cold pressing technique, and evaluate global and local J{sub c} by several physical measurements. We found an intriguing anisotropy in J{sub c} determined by magnetic measurements, which is related to microcrack structures affecting the local J{sub c}. The maximum J{sub c} estimated from magnetization measurements has reached ∼1.9 × 10{sup 5} A/cm{sup 2} under self-field at 4.2 K. Furthermore, microcrack structures are directly observed by magneto-optical imaging technique.

  11. Exact-exchange spin-density functional theory of Wigner localization and phase transitions in quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, Thorsten; Siegmund, Marc; Pankratov, Oleg, E-mail: thorsten.arnold@physik.uni-erlangen.de, E-mail: marc.siegmund@physik.uni-erlangen.de [Lehrstuhl fuer Theoretische Festkoerperphysik, Universitaet Erlangen-Nuernberg, Staudtstrasse 7 B2, D-91058 Erlangen (Germany)

    2011-08-24

    We apply exact-exchange spin-density functional theory in the Krieger-Li-Iafrate approximation to interacting electrons in quantum rings of different widths. The rings are threaded by a magnetic flux that induces a persistent current. A weak space and spin symmetry breaking potential is introduced to allow for localized solutions. As the electron-electron interaction strength described by the dimensionless parameter r{sub S} is increased, we observe-at a fixed spin magnetic moment-the subsequent transition of both spin sub-systems from the Fermi liquid to the Wigner crystal state. A dramatic signature of Wigner crystallization is that the persistent current drops sharply with increasing r{sub S}. We observe simultaneously the emergence of pronounced oscillations in the spin-resolved densities and in the electron localization functions indicating a spatial electron localization showing ferrimagnetic order after both spin sub-systems have undergone the Wigner crystallization. The critical r{sub S}{sup c} at the transition point is substantially smaller than in a fully spin-polarized system and decreases further with decreasing ring width. Relaxing the constraint of a fixed spin magnetic moment, we find that on increasing r{sub S} the stable phase changes from an unpolarized Fermi liquid to an antiferromagnetic Wigner crystal and finally to a fully polarized Fermi liquid.

  12. Exact-exchange spin-density functional theory of Wigner localization and phase transitions in quantum rings.

    Science.gov (United States)

    Arnold, Thorsten; Siegmund, Marc; Pankratov, Oleg

    2011-08-24

    We apply exact-exchange spin-density functional theory in the Krieger-Li-Iafrate approximation to interacting electrons in quantum rings of different widths. The rings are threaded by a magnetic flux that induces a persistent current. A weak space and spin symmetry breaking potential is introduced to allow for localized solutions. As the electron-electron interaction strength described by the dimensionless parameter r(S) is increased, we observe-at a fixed spin magnetic moment-the subsequent transition of both spin sub-systems from the Fermi liquid to the Wigner crystal state. A dramatic signature of Wigner crystallization is that the persistent current drops sharply with increasing r(S). We observe simultaneously the emergence of pronounced oscillations in the spin-resolved densities and in the electron localization functions indicating a spatial electron localization showing ferrimagnetic order after both spin sub-systems have undergone the Wigner crystallization. The critical r(S)(c) at the transition point is substantially smaller than in a fully spin-polarized system and decreases further with decreasing ring width. Relaxing the constraint of a fixed spin magnetic moment, we find that on increasing r(S) the stable phase changes from an unpolarized Fermi liquid to an antiferromagnetic Wigner crystal and finally to a fully polarized Fermi liquid.

  13. Highly accurate local pseudopotentials of Li, Na, and Mg for orbital free density functional theory

    Science.gov (United States)

    Legrain, Fleur; Manzhos, Sergei

    2015-02-01

    We present a method to make highly accurate pseudopotentials for use with orbital-free density functional theory (OF-DFT) with given exchange-correlation and kinetic energy functionals, which avoids the compounding of errors of Kohn-Sham DFT and OF-DFT. The pseudopotentials are fitted to reference (experimental or highly accurate quantum chemistry) values of interaction energies, geometries, and mechanical properties, using a genetic algorithm. This can enable routine large-scale ab initio simulations of many practically relevant materials. Pseudopotentials for Li, Na, and Mg resulting in accurate geometries and energies of different phases as well as of vacancy formation and bulk moduli are presented as examples.

  14. Effectiveness of eugenol sedation to reduce the metabolic rates of cool and warm water fish at high loading densities

    Science.gov (United States)

    Cupp, Aaron R.; Hartleb, Christopher F.; Fredricks, Kim T.; Gaikowski, Mark P.

    2016-01-01

    Effects of eugenol (AQUI-S®20E, 10% active eugenol) sedation on cool water, yellow perch Perca flavescens (Mitchill), and warm water, Nile tilapia Oreochromis niloticus L. fish metabolic rates were assessed. Both species were exposed to 0, 10, 20 and 30 mg L−1 eugenol using static respirometry. In 17°C water and loading densities of 60, 120 and 240 g L−1, yellow perch controls (0 mg L−1 eugenol) had metabolic rates of 329.6–400.0 mg O2 kg−1 h−1, while yellow perch exposed to 20 and 30 mg L−1 eugenol had significantly reduced metabolic rates of 258.4–325.6 and 189.1–271.0 mg O2 kg−1 h−1 respectively. Nile tilapia exposed to 30 mg L−1 eugenol had a significantly reduced metabolic rate (424.5 ± 42.3 mg O2 kg−1 h−1) relative to the 0 mg L−1 eugenol control (546.6 ± 53.5 mg O2 kg−1 h−1) at a loading density of 120 g L−1 in 22°C water. No significant differences in metabolic rates for Nile tilapia were found at 240 or 360 g L−1 loading densities when exposed to eugenol. Results suggest that eugenol sedation may benefit yellow perch welfare at high densities (e.g. live transport) due to a reduction in metabolic rates, while further research is needed to assess the benefits of eugenol sedation on Nile tilapia at high loading densities.

  15. Mobilising sustainable local government revenue in Ghana: modelling property rates and business taxes

    Directory of Open Access Journals (Sweden)

    Samuel B Biitir

    2015-06-01

    Full Text Available Property rates and business operating license fees constitute the major revenue sources for local government authorities. Accurate assessment of these revenues enhances the revenue base and effectiveness of their generation. Assessment of property rates and business operating license fees have been identified as one of the limiting factors that inhibit the revenue potential of local government authorities. Assessment must obey the principles of taxation such as efficiency, equity and fairness, adequacy, administrative feasibility and political acceptability. Over the years, the Sekondi-Takoradi Metropolitan Assembly (STMA acknowledges that, it has had problems in ensuring equity and fairness in the assessment of property rates and business operating license fees. The paper reports on a computer modelling study carried out to introduce measure to ensure equity and fairness in assessing tax objects. A computer application has been developed with quantitative measures to evaluate and assess equity in tax assessment. A test run of the system has been successful and a pilot test is currently being implemented by STMA.

  16. Locating the rate-limiting step for the interaction of hydrogen with Mg(0001) using density-functional theory calculations and rate theory

    DEFF Research Database (Denmark)

    Vegge, Tejs

    2004-01-01

    The dissociation of molecular hydrogen on a Mgs0001d surface and the subsequent diffusion of atomic hydrogen into the magnesium substrate is investigated using Density Functional Theory (DFT) calculations and rate theory. The minimum energy path and corresponding transition states are located using...... the nudged elastic band method, and rates of the activated processes are calculated within the harmonic approximation to transition state rate theory, using both classical and quantum partition functions based atomic vibrational frequencies calculated by DFT. The dissociation/recombination of H2 is found...... to be rate-limiting for the ab- and desorption of hydrogen, respectively. Zero-point energy contributions are found to be substantial for the diffusion of atomic hydrogen, but classical rates are still found to be within an order of magnitude at room temperature....

  17. Effects of Plant Density and Nitrogen Application Rate on Grain Yield and Nitrogen Uptake of Super Hybrid Rice

    Institute of Scientific and Technical Information of China (English)

    LIN Xian-qing; ZHU De-feng; CHEN Hui-zhe; ZHANG Yu-ping

    2009-01-01

    The nitrogen uptake, yield and its components for two super-high-yielding hybrid rice combinations, Guodao 6 and Eryou 7954 were investigated under different plant densities (15, 18, and 21 plants/m2) and different nitrogen application rates (120, 150, 180, and 210 kg/hm2). The experiment was conducted on loam soil during 2004-2006 at the experimental farm of the China National Rice Research Institute in Hangzhou, China. In these years, the two hybrid rice clearly showed higher yield at a plant density of 15 plants/m2 with a nitrogen application rate of 180 kg/hm2. Guodao 6 produced an average grain yield of 10 215.6 kg/hm2 across the three years, while the yield of Eryou 7954 was 9 633.0 kg/hm2. With fewer plants per unit-area and larger plants in the plots, the two hybrid rice produced more panicles per plant in three years. The highest nitrogen uptake of the two hybrid rice was at a plant density of 15 plants/m2 with a nitrogen application rate of 180 kg/hm2. Further increasing nitrogen application rate was not advantageous for nitrogen uptake in super-high-yielding rice under the same plant density.

  18. Smoothness and asymptotic estimates of densities for SDEs with locally smooth coefficients and applications to square root-type diffusions

    CERN Document Server

    De Marco, Stefano

    2011-01-01

    We study smoothness of densities for the solutions of SDEs whose coefficients are smooth and nondegenerate only on an open domain $D$. We prove that a smooth density exists on $D$ and give upper bounds for this density. Under some additional conditions (mainly dealing with the growth of the coefficients and their derivatives), we formulate upper bounds that are suitable to obtain asymptotic estimates of the density for large values of the state variable ("tail" estimates). These results specify and extend some results by Kusuoka and Stroock [J. Fac. Sci. Univ. Tokyo Sect. IA Math. 32 (1985) 1--76], but our approach is substantially different and based on a technique to estimate the Fourier transform inspired from Fournier [Electron. J. Probab. 13 (2008) 135--156] and Bally [Integration by parts formula for locally smooth laws and applications to equations with jumps I (2007) The Royal Swedish Academy of Sciences]. This study is motivated by existing models for financial securities which rely on SDEs with non-...

  19. A study of increasing radical density and etch rate using remote plasma generator system

    Science.gov (United States)

    Lee, Jaewon; Kim, Kyunghyun; Cho, Sung-Won; Chung, Chin-Wook

    2013-09-01

    To improve radical density without changing electron temperature, remote plasma generator (RPG) is applied. Multistep dissociation of the polyatomic molecule was performed using RPG system. RPG is installed to inductively coupled type processing reactor; electrons, positive ions, radicals and polyatomic molecule generated in RPG and they diffused to processing reactor. The processing reactor dissociates the polyatomic molecules with inductively coupled power. The polyatomic molecules are dissociated by the processing reactor that is operated by inductively coupled power. Therefore, the multistep dissociation system generates more radicals than single-step system. The RPG was composed with two cylinder type inductively coupled plasma (ICP) using 400 kHz RF power and nitrogen gas. The processing reactor composed with two turn antenna with 13.56 MHz RF power. Plasma density, electron temperature and radical density were measured with electrical probe and optical methods.

  20. The power spectra of CMB and density fluctuations seeded by local cosmic strings

    CERN Document Server

    Contaldi, C; Magueijo, J; Contaldi, Carlo; Hindmarsh, Mark; Magueijo, Joao

    1999-01-01

    We compute the power spectra in the cosmic microwave background and cold dark matter (CDM) fluctuations seeded by strings, using the largest string simulations performed so far to evaluate the two-point functions of their stress energy tensor. We find that local strings differ from global defects in that the scalar components of the stress-energy tensor dominate over vector and tensor components. This result has far reaching consequences. We find that cosmic strings exhibit a single Doppler peak of acceptable height at high although the CDM power spectrum in the ``standard'' cosmology (flat geometry, zero cosmological constant, 5% baryonic component) is the wrong shape to fit large scale structure data.

  1. Local control theory using trajectory surface hopping and linear-response time-dependent density functional theory.

    Science.gov (United States)

    Curchod, Basile F E; Penfold, Thomas J; Rothlisberger, Ursula; Tavernelli, Ivano

    2013-01-01

    The implementation of local control theory using nonadiabatic molecular dynamics within the framework of linear-response time-dependent density functional theory is discussed. The method is applied to study the photoexcitation of lithium fluoride, for which we demonstrate that this approach can efficiently generate a pulse, on-the-fly, able to control the population transfer between two selected electronic states. Analysis of the computed control pulse yields insights into the photophysics of the process identifying the relevant frequencies associated to the curvature of the initial and final state potential energy curves and their energy differences. The limitations inherent to the use of the trajectory surface hopping approach are also discussed.

  2. Lattice specific heat and local density of states of Ni-based dilute alloys at low temperature

    Indian Academy of Sciences (India)

    P D Semlaty; Kapil Dev; P N Ram

    2006-06-01

    A detailed theoretical study of the low-temperature lattice specific heat of Ni-based dilute alloys has been carried out. Lattice Green's function method has been used to calculate the local density of states of substitutional impurities and lattice specific heat in different alloys. The resonance condition has been investigated for possible occurrence of resonance modes. Except in NiCr and NiMn, low-frequency resonance modes have been obtained in all the alloys. However, no localized mode was obtained. The impurity-induced increase in lattice specific heat is explained on the basis of the obtained resonance modes. The calculation shows an excellent agreement with the measured lattice specific heat in these alloys

  3. Time-Local Equation for the Exact Optimized Effective Potential in Time-Dependent Density Functional Theory

    Science.gov (United States)

    Liao, Sheng-Lun; Ho, Tak-San; Rabitz, Herschel; Chu, Shih-I.

    2017-06-01

    A long-standing challenge in the time-dependent density functional theory is to efficiently solve the exact time-dependent optimized effective potential (TDOEP) integral equation derived from orbital-dependent functionals, especially for the study of nonadiabatic dynamics in time-dependent external fields. In this Letter, we formulate a completely equivalent time-local TDOEP equation that admits a unique real-time solution in terms of time-dependent Kohn-Sham and effective memory orbitals. The time-local formulation is numerically implemented, with the incorporation of exponential memory loss to address the unaccounted for correlation component in the exact-exchange-only functional, to enable the study of the many-electron dynamics of a one-dimensional hydrogen chain. It is shown that the long time behavior of the electric dipole converges correctly and the zero-force theorem is fulfilled in the current implementation.

  4. Self-consistent local-density approximation with model Coulomb pair-correlation functions for electronic systems

    Science.gov (United States)

    Gritsenko, O. V.; Rubio, A.; Balbás, L. C.; Alonso, J. A.

    1993-03-01

    The model Coulomb pair-correlation functions proposed several years ago by Gritsenko, Bagaturyants, Kazansky, and Zhidomirov are incorporated into the self-consistent local-density approximation (LDA) scheme for electronic systems. Different correlation functions satisfying well-established local boundary conditions and integral conditions have been tested by performing LDA calculations for closed-shell atoms. Those correlation functions contain a single parameter which can be optimized by fitting the atomic correlation energies to empirical data. In this way, a single (universal) value of the parameter is found to give a very good fit for all the atoms studied. The results provide a substantial improvement of calculated correlation energies as compared to the usual LDA functionals and the scheme should be useful for molecular and cluster calculations.

  5. Signature of a Fano-resonance in a plasmonic meta-molecule's local density of optical states

    CERN Document Server

    Frimmer, Martin; Koenderink, A Femius

    2011-01-01

    We present measurements on plasmonic meta-molecules under local excitation using cathodoluminescence which show a spatial redistribution of the local density of optical states (LDOS) at the same frequency where a sharp spectral Fano-feature in the extinction cross section has been observed. Our analytical model shows that both near- and far-field effects arise due to interference of the same two eigenmodes of the system. We present quantitative insights both in a bare state, and in a dressed state picture that describe plasmonic Fano interference either as near-field amplitude transfer between three coupled bare states, or as interference of two uncoupled eigenmodes in the far field. We identify the same eigenmode causing a dip in extinction to strongly enhance the radiative LDOS, making it a promising candidate for spontaneous emission control.

  6. Ordinary mode reflectometry. Modification of the scattering and cut-off responses due to the shape of localized density fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Fanack, C.; Boucher, I.; Heuraux, S.; Leclert, G. [Centre National de la Recherche Scientifique (CNRS), 54 - Nancy (France). Lab. de Physique du Solide; Clairet, F.; Zou, X.L. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    1996-01-01

    Ordinary wave reflectometry in a plasma containing a localized density perturbation is studied with a 1-D model. The phase response is studied as a function of the wavenumber and position of the perturbation. It is shown that it strongly depends upon the perturbation shape and size. For a small perturbation wavenumber, the response is due to the oscillation of the cut-off layer. For larger wavenumbers, two regimes are found: for a broad perturbation, the phase response is an image of the perturbation itself; for a narrow perturbation, it is rather an image of the Fourier transform. For tokamak plasmas it turns out that, for the fluctuation spectra usually observed, the phase response comes primarily from those fluctuations that are localized at the cut-off. Results of a 2-D numerical model show that geometry effects are negligible for the scattering by radial fluctuations. (author). 18 refs.

  7. Quasi-1D van der Waals materials as high current-density local interconnects (Conference Presentation)

    Science.gov (United States)

    Stolyarov, Maxim; Aytan, Ece; Bloodgood, Matthew; Salguero, Tina T.; Balandin, Alexander A.

    2016-09-01

    The continuous downscaling of interconnect dimensions in combination with the introduction of low-k dielectrics has increased the number of heat dissipation, integration and reliability challenges in modern electronics. As a result, there is a strong need for new materials that have high current-carrying capacity for applications as nanoscale interconnects. In this presentation, we show that quasi-one-dimensional (1D) van der Waals metals such as TaSe3 have excellent breakdown current density exceeding that of 5 MA/cm2. This value is above that currently achievable in conventional copper or aluminum wires. The quasi-1D van der Waals materials are characterized by strong bonds along one dimension and weak van der Waals bonds along two other dimensions. The material for this study was grown by the chemical vapor transport (CVT) method. Both mechanical and chemical exfoliation methods were used to fabricate nanowires with lateral dimensions below 100 nm. The dimensions of the quasi-1D nanowires were verified with scanning electron microscopy (SEM) and atomic force microscopy (AFM). The metal (Ti/Au) contacts for the electrical characterization were deposited using electron beam evaporation (EBE). The measurements were conducted on a number of prototype interconnects with multiple electric contacts to ensure reproducibility. The obtained results suggest that quasi-1D van der Waals metals present a feasible alternative to conventional copper interconnects in terms of the current-carrying capacity and the breakdown current-density. This work was supported, in part, by the SRC and DARPA through STARnet Center for Function Accelerated nanoMaterial Engineering (FAME).

  8. A Surface Heat Disturbance Method for Measuring Local TIssue Blood Perfusion Rate

    Institute of Scientific and Technical Information of China (English)

    PengJianshu; TianYongquan

    1996-01-01

    A non-damage method for measuring local tissue blood perfusion rate by surface heat disturbance and its two special embodiments for realizing this measurement are presented in this paper,In the derivation of mathematical model,the Pennes equation is used,and two parameters which are very diffcult to be known-the arterial blood temperature Ta and the metabolic heat generation rate qm,have been eliminated.So if has provided a feasible basis for application.In this paper,the performance and the adaptable condition of the measurement method and its structure peculiarities are discussed over a wide variety of parameters.Moreover,the effectiveness of the measurement method has been demonstrated by means of the quantitative measurement of tissue in vitro,the comparative measurement of animal under artificial perfusion and the dependence measurement in human body.

  9. Radial Distribution of Production Rates, Loss Rates and Densities Corresponding to Ion Masses <=40 amu in the Inner Coma of Comet Halley: Composition and Chemistry

    CERN Document Server

    Haider, S A; Bhardwaj, Anil

    2005-01-01

    In this paper we have studied the chemistry of C, H, N, O, and S compounds corresponding to ions of masses <=40 amu in the inner coma of the comet 1P/Halley. The production rates, loss rates, and ion mass densities are calculated using the Analytical Yield Spectrum approach and solving coupled continuity equation controlled by the steady state photochemical equilibrium condition. The primary ionization sources in the model are solar EUV photons, photoelectrons, and auroral electrons of the solar wind origin. The chemical model couples ion-neutral, electron-neutral, photon-neutral and electron-ion reactions among ions, neutrals, electrons, and photons through over 600 chemical reactions. Of the 46 ions considered in the model the chemistry of 24 important ions are discussed in this paper. The calculated ion mass densities are compared with the Giotto Ion Mass Spectrometer (IMS) and Neutral Mass Spectrometer (NMS) data at radial distances 1500, 3500, and 6000 km.

  10. Predicting local dengue transmission in Guangzhou, China, through the influence of imported cases, mosquito density and climate variability.

    Directory of Open Access Journals (Sweden)

    Shaowei Sang

    Full Text Available Each year there are approximately 390 million dengue infections worldwide. Weather variables have a significant impact on the transmission of Dengue Fever (DF, a mosquito borne viral disease. DF in mainland China is characterized as an imported disease. Hence it is necessary to explore the roles of imported cases, mosquito density and climate variability in dengue transmission in China. The study was to identify the relationship between dengue occurrence and possible risk factors and to develop a predicting model for dengue's control and prevention purpose.Three traditional suburbs and one district with an international airport in Guangzhou city were selected as the study areas. Autocorrelation and cross-correlation analysis were used to perform univariate analysis to identify possible risk factors, with relevant lagged effects, associated with local dengue cases. Principal component analysis (PCA was applied to extract principal components and PCA score was used to represent the original variables to reduce multi-collinearity. Combining the univariate analysis and prior knowledge, time-series Poisson regression analysis was conducted to quantify the relationship between weather variables, Breteau Index, imported DF cases and the local dengue transmission in Guangzhou, China. The goodness-of-fit of the constructed model was determined by pseudo-R2, Akaike information criterion (AIC and residual test. There were a total of 707 notified local DF cases from March 2006 to December 2012, with a seasonal distribution from August to November. There were a total of 65 notified imported DF cases from 20 countries, with forty-six cases (70.8% imported from Southeast Asia. The model showed that local DF cases were positively associated with mosquito density, imported cases, temperature, precipitation, vapour pressure and minimum relative humidity, whilst being negatively associated with air pressure, with different time lags.Imported DF cases and mosquito

  11. The effects of plant density of Melastoma malabathricum on the erosion rate of slope soil at different slope orientations

    Institute of Scientific and Technical Information of China (English)

    Aimee Halim n; Osman Normaniza

    2015-01-01

    abstract Malaysia's cut slopes, especially for road lines accommodation, are prone to erosions and landslides. These problems mainly occur due to lack of vegetation cover and strong erosive forces. In addition, the topography factors have also become a major factor affecting soil degradation. Thus, this study is aimed at determining the effects of planting density of a selected species, namely Melastoma malabathricum;one, two, and three seedlings per box, on the erosion rate at selected slopes of different orientation (morning and evening sun) at the Guthrie Corridor Expressway, Selangor. In six months of observation, treatment with three seedlings/box on the morning sun slope showed a lower erosion rate by 69.2%than those with the same treatment on the evening sun slope. In addition, the treatment of the three seedlings recorded at month six (final observation) had the highest reduction of soil saturation level (STL), by 23.6%. Furthermore, the physiological values of the species studied, grown on the morning sun slope, were higher in terms of stomatal conductance and photosynthetic rate by 12.1%and15.8%(three seedlings/box), respectively. The overall results showed that plant density was inversely related to the STL and erosion rate on the slope. In conclusion, a planting density of three seedlings/box and morning sun orientation gave positive effects on the plant's physiological performance of the slope, reducing the STL, as well as alleviating the erosion rate of slope soils.

  12. RELATIONSHIP BETWEEN CLIMATE VARIABLES, TRUNK GROWTH RATE AND WOOD DENSITY OF Eucalyptus grandis W. Mill ex Maiden TREES

    Directory of Open Access Journals (Sweden)

    Carlos Roberto Sette Jr

    2016-04-01

    Full Text Available ABSTRACT Climatic conditions stimulates the cambial activity of plants, and cause significant changes in trunk diameter growth and wood characteristics. The objective of this study was to evaluate the influence of climate variables in the diameter growth rate of the stem and the wood density of Eucalyptus grandis trees in different classes of the basal area. A total of 25 Eucalyptus trees at 22 months of age were selected according to the basal area distribution. Dendrometer bands were installed at the height of 1.30 meters (DBH to monitor the diameter growth every 14 days, for 26 months. After measuring growth, the trees were felled and wood discs were removed at the DBH level to determine the radial density profile through x-ray microdensitometry and then re-scale the average values every 14 days. Climatic variables for the monitoring period were obtained and grouped every 14 days. The effect of the climate variables was determined by maximum and minimum growth periods in assessing trunk growth. These growth periods were related with precipitation, average temperature and relative air humidity. The re-scaled wood density values, calculated using the radial growth of the tree trunks measured accurately with steel dendrometers, enabled the determination of the relationship of small changes in wood density and the effect of the climatic variations and growth rate of eucalyptus tree trunks. A high sensitivity of the wood density to variation in precipitation levels was found.

  13. Localized delivery of low-density lipoprotein docosahexaenoic acid nanoparticles to the rat brain using focused ultrasound.

    Science.gov (United States)

    Mulik, Rohit S; Bing, Chenchen; Ladouceur-Wodzak, Michelle; Munaweera, Imalka; Chopra, Rajiv; Corbin, Ian R

    2016-03-01

    Focused ultrasound exposures in the presence of microbubbles can achieve transient, non-invasive, and localized blood-brain barrier (BBB) opening, offering a method for targeted delivery of therapeutic agents into the brain. Low-density lipoprotein (LDL) nanoparticles reconstituted with docosahexaenoic acid (DHA) could have significant therapeutic value in the brain, since DHA is known to be neuroprotective. BBB opening was achieved using pulsed ultrasound exposures in a localized brain region in normal rats, after which LDL nanoparticles containing the fluorescent probe DiR (1,1'-Dioctadecyl-3,3,3',3'-Tetramethylindotricarbocyanine Iodide) or DHA were administered intravenously. Fluorescent imaging of brain tissue from rats administered LDL-DiR demonstrated strong localization of fluorescence signal in the exposed hemisphere. LDL-DHA administration produced 2 × more DHA in the exposed region of the brain, with a corresponding increase in Resolvin D1 levels, indicating DHA was incorporated into cells and metabolized. Histological evaluation did not indicate any evidence of increased tissue damage in exposed brain regions compared to normal brain. This work demonstrates that localized delivery of DHA to the brain is possible using systemically-administered LDL nanoparticles combined with pulsed focused ultrasound exposures in the brain. This technology could be used in regions of acute brain injury or as a means to target infiltrating tumor cells in the brain.

  14. Local clouds ionization, temperatures, electron densities and interfaces, from GHRS and IMAPS spectra of epsilon Canis Majoris

    CERN Document Server

    Gry, C; Gry, Cecile; Jenkins, Edward B.

    2001-01-01

    The composition and physical properties of several local clouds, including the Local Interstellar Cloud (LIC) in which the Sun is embedded, are derived from absorption features in the UV spectrum of the star epsilon CMa. We derive temperatures and densities for three components by combining our interpretations of the ionization balance of magnesium and the relative population of C II in an excited fine-structure level. We find that for the LIC n(e) = 0.12 +/-0.05 cm-3 and T = 7000 +/-1200 K. We derive the ionization fractions of hydrogen and discuss the ionizing processes. In particular the hydrogen and helium ionizations in the LIC are compatible with photoionization by the local EUV radiation fields from the hot stars and the cloud interface with the hot gas. We confirm the detection of high ionization species : Si III is detected in all clouds and C IV in two of them, including the LIC, suggesting the presence of ionized interfaces around the local clouds.

  15. The HI Content of Galaxies as a Function of Local Density and Large-Scale Environment

    Science.gov (United States)

    Thoreen, Henry; Cantwell, Kelly; Maloney, Erin; Cane, Thomas; Brough Morris, Theodore; Flory, Oscar; Raskin, Mark; Crone-Odekon, Mary; ALFALFA Team

    2017-01-01

    We examine the HI content of galaxies as a function of environment, based on a catalogue of 41527 galaxies that are part of the 70% complete Arecibo Legacy Fast-ALFA (ALFALFA) survey. We use nearest-neighbor methods to characterize local environment, and a modified version of the algorithm developed for the Galaxy and Mass Assembly (GAMA) survey to classify large-scale environment as group, filament, tendril, or void. We compare the HI content in these environments using statistics that include both HI detections and the upper limits on detections from ALFALFA. The large size of the sample allows to statistically compare the HI content in different environments for early-type galaxies as well as late-type galaxies. This work is supported by NSF grants AST-1211005 and AST-1637339, the Skidmore Faculty-Student Summer Research program, and the Schupf Scholars program.

  16. INT-WFS + 2dFGRS The Local Space & Luminosity Density

    CERN Document Server

    Cross, N; Lemon, D; Cross, Nicholas; Driver, Simon; Lemon, David

    2000-01-01

    We discuss the quantification of the local galaxy population and the impact of the ``New Era of Wide-Field Astronomy'' on this field, and, in particular, systematic errors in the measurement of the Luminosity Function. New results from the 2dFGRS are shown in which some of these selection effects have been removed. We introduce an INT-WFS project which will further reduce the selection biases. We show that there is a correlation between the surface brightness and the luminosity of galaxies and that new technologies are having a big impact on this field. Finally selection criteria from different surveys are modelled and it is shown that some of the major selection effects are surface brightness selection effects.

  17. Galaxy And Mass Assembly (GAMA): Refining the Local Galaxy Merger Rate using Morphological Information

    CERN Document Server

    Casteels, Kevin R V; Bamford, Steven P; Salvador-Sole, Eduard; Norberg, Peder R; Agius, Nicola K; Baldry, Ivan; Brough, Sarah; Brown, Michael J I; Drinkwater, Michael J; Driver, Simon P; Graham, Alister W; Bland-Hawthorn, Joss; Hopkins, Andrew M; Kelvin, Lee S; Lopez-Sanchez, Angel R; Loveday, Jon; Robotham, Aaron S G; Vazquez-Mata, Jose A

    2014-01-01

    We use the Galaxy And Mass Assembly (GAMA) survey to measure the local Universe mass dependent merger fraction and merger rate using galaxy pairs and the CAS structural method, which identifies highly asymmetric merger candidate galaxies. Our goals are to determine which types of mergers produce highly asymmetrical galaxies, and to provide a new measurement of the local galaxy major merger rate. We examine galaxy pairs at stellar mass limits down to $M_{*} = 10^{8}M_{\\odot}$ with mass ratios of $$4:1) the lower mass companion becomes highly asymmetric, while the larger galaxy is much less affected. The fraction of highly asymmetric paired galaxies which have a major merger companion is highest for the most massive galaxies and drops progressively with decreasing mass. We calculate that the mass dependent major merger fraction is fairly constant at $\\sim1.3-2\\%$ between $10^{9.5}

  18. Turnover and vacancy rates for registered nurses: do local labor market factors matter?

    Science.gov (United States)

    Rondeau, Kent V; Williams, Eric S; Wagar, Terry H

    2008-01-01

    Turnover of nursing staff is a significant issue affecting health care cost, quality, and access. In recent years, a worldwide shortage of skilled nurses has resulted in sharply higher vacancy rates for registered nurses in many health care organizations. Much research has focused on the individual, group, and organizational determinants of turnover. Labor market factors have also been suggested as important contributors to turnover and vacancy rates but have received limited attention by scholars. This study proposes and tests a conceptual model showing the relationships of organization-market fit and three local labor market factors with organizational turnover and vacancy rates. The model is tested using ordinary least squares regression with data collected from 713 Canadian hospitals and nursing homes. Results suggest that, although modest in their impact, labor market and the organization-market fit factors do make significant yet differential contributions to turnover and vacancy rates for registered nurses. Knowledge of labor market factors can substantially shape an effective campaign to recruit and retain nurses. This is particularly true for employers who are perceived to be "employers-of-choice."

  19. The Yulong Mountains Structural Culmination: Tectonic and Geomorphic Controls on Localized Uplift Rates and Exhumation

    Science.gov (United States)

    Studnicki-Gizbert, C.; Wang, Y.; Burchfiel, B. C.; Chen, L.

    2005-12-01

    The active tectonics of the Eastern margin of the Tibetan plateau are characterised by left-lateral faults accommodating clockwise rotation of crustal fragments and normal faults accommodating generally east-west directed extension in the wake of the northward propagating eastern Himalayan syntaxis. Within the corridor of transtensional deformation that extends from Dali to Zhongdian, the Jinsha (Yangzi) river interacts with a closed circuit of normal and transtensional faults and results in localised high mean and maximum elevations, anomalously high rock uplift rates and the exposure of deep structural levels and metamorphic rocks in the core of fault-bounded antiformal dome. Flexural uplift of the footwalls of the bounding normal faults due to tectonic and erosional unroofing can plausibly explain the high elevations in the core of the range. However, geomorphic indicators of high uplift rates do not unequivocally coincide with the distribution of uplift and subsidence predicted by such a model. Nor does such a model yield any insight into the role of extreme fluvial incision in either accommodating or driving anomalously high uplift rates (and thus total exhumation). Moreover, unlike the association of antiformal culminations with transverse rivers reported in many compressional belts (Simpson 2004 and references therein), localised erosional unloading ought to relieve vertical stresses driving extensional faulting. Alternatively, we envisage a model somewhat analogous to the reactive diapirs well known from salt tectonics: both tectonic extension and geomorphic unloading weaken and thin the brittle upper crust and accommodate localized, anomalously high rock uplift rates.

  20. Comparison of all morphotype males and various types stocking density of Macrobrachium rosenbergii (De Man on growth and survival rate

    Directory of Open Access Journals (Sweden)

    Mst. Rubia Banu

    2016-05-01

    Full Text Available A study was conducted to appraise the effect of different stocking densities on three male morphotypes named blue claw (BC, orange claw (OC and small male (SM at harvest in all-male culture and assess the growth performance of BC, OC and SM in each isolated culture. Trials involving three stocking densities of all-male prawn viz., 20, 30 and 40 juvenile m−2 were carried out in replicates. After 4 months of culture, BC, OC and SM were sorted from all tanks and restocked at 5 m−2 in treatments BC, OC and SM respectively for 80 days. A difference in prawn density was significant (P < 0.05 affect adversely on morphotypes. The highest survival rate combined with good yields performance was from 20 juvenile m−2 stocking density with 21% BC, 62.5% OC and 16.5% SM respectively. In isolation culture, the average specific growth rate of the SM population (1.22 was significantly higher than that of the OC (1.01 and the BC (0.43 population. The survival rate of the SM population was 100% while others were 72%. Absolute weight of prawn was significantly greater in the OC male (23.87 g than the SM (19.57 g and the BC male (6.31 g. Impacts of isolated culture on population structure were much more pronounced in the SM population than others.

  1. High-Dose-Rate Monotherapy: Safe and Effective Brachytherapy for Patients With Localized Prostate Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Demanes, D. Jeffrey, E-mail: jdemanes@mednet.ucla.edu [California Endocurietherapy at UCLA, Department of Radiation Oncology, David Geffen School of Medicine of University of California at Los Angeles, Los Angeles, CA (United States); Martinez, Alvaro A.; Ghilezan, Michel [William Beaumont Hospital, Royal Oak, MI (United States); Hill, Dennis R.; Schour, Lionel; Brandt, David [California Endocurietherapy, Oakland, CA (United States); Gustafson, Gary [William Beaumont Hospital, Royal Oak, MI (United States)

    2011-12-01

    Purpose: High-dose-rate (HDR) brachytherapy used as the only treatment (monotherapy) for early prostate cancer is consistent with current concepts in prostate radiobiology, and the dose is reliably delivered in a prospectively defined anatomic distribution that meets all the requirements for safe and effective therapy. We report the disease control and toxicity of HDR monotherapy from California Endocurietherapy (CET) and William Beaumont Hospital (WBH) in low- and intermediate-risk prostate cancer patients. Methods and Materials: There were 298 patients with localized prostate cancer treated with HDR monotherapy between 1996 and 2005. Two biologically equivalent hypofractionation protocols were used. At CET the dose was 42 Gy in six fractions (two implantations 1 week apart) delivered to a computed tomography-defined planning treatment volume. At WBH the dose was 38 Gy in four fractions (one implantation) based on intraoperative transrectal ultrasound real-time treatment planning. The bladder, urethral, and rectal dose constraints were similar. Toxicity was scored with the National Cancer Institute Common Toxicity Criteria for Adverse Events version 3. Results: The median follow-up time was 5.2 years. The median age of the patients was 63 years, and the median value of the pretreatment prostate-specific antigen was 6.0 ng/mL. The 8-year results were 99% local control, 97% biochemical control (nadir +2), 99% distant metastasis-free survival, 99% cause-specific survival, and 95% overall survival. Toxicity was scored per event, meaning that an individual patient with more than one symptom was represented repeatedly in the morbidity data table. Genitourinary toxicity consisted of 10% transient Grade 2 urinary frequency or urgency and 3% Grade 3 episode of urinary retention. Gastrointestinal toxicity was <1%. Conclusions: High disease control rates and low morbidity demonstrate that HDR monotherapy is safe and effective for patients with localized prostate cancer.

  2. Tumor Volume Reduction Rate After Preoperative Chemoradiotherapy as a Prognostic Factor in Locally Advanced Rectal Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Yeo, Seung-Gu [Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang (Korea, Republic of); Department of Radiation Oncology, Soonchunhyang University College of Medicine, Cheonan (Korea, Republic of); Kim, Dae Yong, E-mail: radiopiakim@hanmail.net [Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang (Korea, Republic of); Park, Ji Won; Oh, Jae Hwan; Kim, Sun Young; Chang, Hee Jin; Kim, Tae Hyun; Kim, Byung Chang; Sohn, Dae Kyung; Kim, Min Ju [Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang (Korea, Republic of)

    2012-02-01

    Purpose: To investigate the prognostic significance of tumor volume reduction rate (TVRR) after preoperative chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC). Methods and Materials: In total, 430 primary LARC (cT3-4) patients who were treated with preoperative CRT and curative radical surgery between May 2002 and March 2008 were analyzed retrospectively. Pre- and post-CRT tumor volumes were measured using three-dimensional region-of-interest MR volumetry. Tumor volume reduction rate was determined using the equation TVRR (%) = (pre-CRT tumor volume - post-CRT tumor volume) Multiplication-Sign 100/pre-CRT tumor volume. The median follow-up period was 64 months (range, 27-99 months) for survivors. Endpoints were disease-free survival (DFS) and overall survival (OS). Results: The median TVRR was 70.2% (mean, 64.7% {+-} 22.6%; range, 0-100%). Downstaging (ypT0-2N0M0) occurred in 183 patients (42.6%). The 5-year DFS and OS rates were 77.7% and 86.3%, respectively. In the analysis that included pre-CRT and post-CRT tumor volumes and TVRR as continuous variables, only TVRR was an independent prognostic factor. Tumor volume reduction rate was categorized according to a cutoff value of 45% and included with clinicopathologic factors in the multivariate analysis; ypN status, circumferential resection margin, and TVRR were significant prognostic factors for both DFS and OS. Conclusions: Tumor volume reduction rate was a significant prognostic factor in LARC patients receiving preoperative CRT. Tumor volume reduction rate data may be useful for tailoring surgery and postoperative adjuvant therapy after preoperative CRT.

  3. Evaluation of localized muscle fatigue using power spectral density analysis of the electromyogram

    Science.gov (United States)

    Lafevers, E. V.

    1974-01-01

    Surface electromyograms (EMGs) taken from three upper torso muscles during a push-pull task were analyzed by a power spectral density technique to determine the operational feasibility of the technique for identifying changes in the EMGs resulting from muscular fatigue. The EMGs were taken from four subjects under two conditions (1) in shirtsleeves and (2) in a pressurized space suit. This study confirmed that frequency analysis of dynamic muscle activity is capable of providing reliable data for many industrial applications where fatigue may be of practical interest. The results showed significant effects of the pressurized space suit on the pattern of shirtsleeve fatigue responses of the muscles. The data also revealed (1) reliable differences between muscles in fatigue-induced responses to various locations in the reach envelope at which the subjects were required to perform the push-pull exercise and (2) the differential sensitivity of muscles to the various reach positions in terms of fatigue-related shifts in EMG power.

  4. Exploiting the locality of periodic subsystem density-functional theory: efficient sampling of the Brillouin zone

    Science.gov (United States)

    Genova, Alessandro; Pavanello, Michele

    2015-12-01

    In order to approximately satisfy the Bloch theorem, simulations of complex materials involving periodic systems are made {{n}\\text{k}} times more complex by the need to sample the first Brillouin zone at {{n}\\text{k}} points. By combining ideas from Kohn-Sham density-functional theory (DFT) and orbital-free DFT, for which no sampling is needed due to the absence of waves, subsystem DFT offers an interesting middle ground capable of sizable theoretical speedups against Kohn-Sham DFT. By splitting the supersystem into interacting subsystems, and mapping their quantum problem onto separate auxiliary Kohn-Sham systems, subsystem DFT allows an optimal topical sampling of the Brillouin zone. We elucidate this concept with two proof of principle simulations: a water bilayer on Pt[1 1 1]; and a complex system relevant to catalysis—a thiophene molecule physisorbed on a molybdenum sulfide monolayer deposited on top of an α-alumina support. For the latter system, a speedup of 300% is achieved against the subsystem DTF reference by using an optimized Brillouin zone sampling (600% against KS-DFT).

  5. mBEEF: An accurate semi-local Bayesian error estimation density functional

    Science.gov (United States)

    Wellendorff, Jess; Lundgaard, Keld T.; Jacobsen, Karsten W.; Bligaard, Thomas

    2014-04-01

    We present a general-purpose meta-generalized gradient approximation (MGGA) exchange-correlation functional generated within the Bayesian error estimation functional framework [J. Wellendorff, K. T. Lundgaard, A. Møgelhøj, V. Petzold, D. D. Landis, J. K. Nørskov, T. Bligaard, and K. W. Jacobsen, Phys. Rev. B 85, 235149 (2012)]. The functional is designed to give reasonably accurate density functional theory (DFT) predictions of a broad range of properties in materials physics and chemistry, while exhibiting a high degree of transferability. Particularly, it improves upon solid cohesive energies and lattice constants over the BEEF-vdW functional without compromising high performance on adsorption and reaction energies. We thus expect it to be particularly well-suited for studies in surface science and catalysis. An ensemble of functionals for error estimation in DFT is an intrinsic feature of exchange-correlation models designed this way, and we show how the Bayesian ensemble may provide a systematic analysis of the reliability of DFT based simulations.

  6. Local strain energy density to assess the multiaxial fatigue strength of titanium alloys

    Directory of Open Access Journals (Sweden)

    Filippo Berto

    2016-07-01

    Full Text Available The present paper investigates the multiaxial fatigue strength of sharp V-notched components made of titanium grade 5 alloy (Ti-6Al-4V. Axisymmetric notched specimens have been tested under combined tension and torsion fatigue loadings, both proportional and non-proportional, taking into account different nominal load ratios (R = -1 and 0. All tested samples have a notch root radius about equal to 0.1 mm, a notch depth of 6 mm and an opening angle of 90 degrees. The fatigue results obtained by applying multiaxial loadings are discussed together with those related to pure tension and pure torsion experimental fatigue tests, carried out on both smooth and notched specimens at load ratios R ranging between -3 and 0.5. Altogether, more than 250 fatigue results (19 S-N curves are examined, first on the basis of nominal stress amplitudes referred to the net area and secondly by means of the strain energy density averaged over a control volume embracing the V-notch tip. The effect of the loading mode on the control volume size has been analysed, highlighting a wide difference in the notch sensitivity of the considered material under tension and torsion loadings. Accordingly, the control radius of the considered titanium alloy (Ti-6Al-4V is found to be strongly affected by the loading mode.

  7. Accurate and efficient calculation of van der Waals interactions within density functional theory by local atomic potential approach.

    Science.gov (United States)

    Sun, Y Y; Kim, Yong-Hyun; Lee, Kyuho; Zhang, S B

    2008-10-21

    Density functional theory (DFT) in the commonly used local density or generalized gradient approximation fails to describe van der Waals (vdW) interactions that are vital to organic, biological, and other molecular systems. Here, we propose a simple, efficient, yet accurate local atomic potential (LAP) approach, named DFT+LAP, for including vdW interactions in the framework of DFT. The LAPs for H, C, N, and O are generated by fitting the DFT+LAP potential energy curves of small molecule dimers to those obtained from coupled cluster calculations with single, double, and perturbatively treated triple excitations, CCSD(T). Excellent transferability of the LAPs is demonstrated by remarkable agreement with the JSCH-2005 benchmark database [P. Jurecka et al. Phys. Chem. Chem. Phys. 8, 1985 (2006)], which provides the interaction energies of CCSD(T) quality for 165 vdW and hydrogen-bonded complexes. For over 100 vdW dominant complexes in this database, our DFT+LAP calculations give a mean absolute deviation from the benchmark results less than 0.5 kcal/mol. The DFT+LAP approach involves no extra computational cost other than standard DFT calculations and no modification of existing DFT codes, which enables straightforward quantum simulations, such as ab initio molecular dynamics, on biomolecular systems, as well as on other organic systems.

  8. Global effects of local human population density and distance to markets on the condition of coral reef fisheries.

    Science.gov (United States)

    Cinner, Joshua E; Graham, Nicholas A J; Huchery, Cindy; Macneil, M Aaron

    2013-06-01

    Coral reef fisheries support the livelihoods of millions of people but have been severely and negatively affected by anthropogenic activities. We conducted a systematic review of published data on the biomass of coral reef fishes to explore how the condition of reef fisheries is related to the density of local human populations, proximity of the reef to markets, and key environmental variables (including broad geomorphologic reef type, reef area, and net productivity). When only population density and environmental covariates were considered, high variability in fisheries conditions at low human population densities resulted in relatively weak explanatory models. The presence or absence of human settlements, habitat type, and distance to fish markets provided a much stronger explanatory model for the condition of reef fisheries. Fish biomass remained relatively low within 14 km of markets, then biomass increased exponentially as distance from reefs to markets increased. Our results suggest the need for an increased science and policy focus on markets as both a key driver of the condition of reef fisheries and a potential source of solutions.

  9. Queuing Theory Based Co-Channel Interference Analysis Approach for High-Density Wireless Local Area Networks

    Science.gov (United States)

    Zhang, Jie; Han, Guangjie; Qian, Yujie

    2016-01-01

    Increased co-channel interference (CCI) in wireless local area networks (WLANs) is bringing serious resource constraints to today’s high-density wireless environments. CCI in IEEE 802.11-based networks is inevitable due to the nature of the carrier sensing mechanism however can be reduced by resource optimization approaches. That means the CCI analysis is basic, but also crucial for an efficient resource management. In this article, we present a novel CCI analysis approach based on the queuing theory, which considers the randomness of end users’ behavior and the irregularity and complexity of network traffic in high-density WLANs that adopts the M/M/c queuing model for CCI analysis. Most of the CCIs occur when multiple networks overlap and trigger channel contentions; therefore, we use the ratio of signal-overlapped areas to signal coverage as a probabilistic factor to the queuing model to analyze the CCI impacts in highly overlapped WLANs. With the queuing model, we perform simulations to see how the CCI influences the quality of service (QoS) in high-density WLANs. PMID:27563896

  10. Queuing Theory Based Co-Channel Interference Analysis Approach for High-Density Wireless Local Area Networks.

    Science.gov (United States)

    Zhang, Jie; Han, Guangjie; Qian, Yujie

    2016-08-23

    Increased co-channel interference (CCI) in wireless local area networks (WLANs) is bringing serious resource constraints to today's high-density wireless environments. CCI in IEEE 802.11-based networks is inevitable due to the nature of the carrier sensing mechanism however can be reduced by resource optimization approaches. That means the CCI analysis is basic, but also crucial for an efficient resource management. In this article, we present a novel CCI analysis approach based on the queuing theory, which considers the randomness of end users' behavior and the irregularity and complexity of network traffic in high-density WLANs that adopts the M/M/c queuing model for CCI analysis. Most of the CCIs occur when multiple networks overlap and trigger channel contentions; therefore, we use the ratio of signal-overlapped areas to signal coverage as a probabilistic factor to the queuing model to analyze the CCI impacts in highly overlapped WLANs. With the queuing model, we perform simulations to see how the CCI influences the quality of service (QoS) in high-density WLANs.

  11. GAS SURFACE DENSITY, STAR FORMATION RATE SURFACE DENSITY, AND THE MAXIMUM MASS OF YOUNG STAR CLUSTERS IN A DISK GALAXY. II. THE GRAND-DESIGN GALAXY M51

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Lopezlira, Rosa A. [On sabbatical leave from the Centro de Radioastronomia y Astrofisica, UNAM, Campus Morelia, Michoacan, C.P. 58089, Mexico. (Mexico); Pflamm-Altenburg, Jan; Kroupa, Pavel, E-mail: r.gonzalez@crya.unam.mx [Argelander Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany)

    2013-06-20

    We analyze the relationship between maximum cluster mass and surface densities of total gas ({Sigma}{sub gas}), molecular gas ({Sigma}{sub H{sub 2}}), neutral gas ({Sigma}{sub H{sub I}}), and star formation rate ({Sigma}{sub SFR}) in the grand-design galaxy M51, using published gas data and a catalog of masses, ages, and reddenings of more than 1800 star clusters in its disk, of which 223 are above the cluster mass distribution function completeness limit. By comparing the two-dimensional distribution of cluster masses and gas surface densities, we find for clusters older than 25 Myr that M{sub 3rd}{proportional_to}{Sigma}{sub H{sub I}{sup 0.4{+-}0.2}}, whereM{sub 3rd} is the median of the five most massive clusters. There is no correlation with{Sigma}{sub gas},{Sigma}{sub H2}, or{Sigma}{sub SFR}. For clusters younger than 10 Myr, M{sub 3rd}{proportional_to}{Sigma}{sub H{sub I}{sup 0.6{+-}0.1}} and M{sub 3rd}{proportional_to}{Sigma}{sub gas}{sup 0.5{+-}0.2}; there is no correlation with either {Sigma}{sub H{sub 2}} or{Sigma}{sub SFR}. The results could hardly be more different from those found for clusters younger than 25 Myr in M33. For the flocculent galaxy M33, there is no correlation between maximum cluster mass and neutral gas, but we have determined M{sub 3rd}{proportional_to}{Sigma}{sub gas}{sup 3.8{+-}0.3}, M{sub 3rd}{proportional_to}{Sigma}{sub H{sub 2}{sup 1.2{+-}0.1}}, and M{sub 3rd}{proportional_to}{Sigma}{sub SFR}{sup 0.9{+-}0.1}. For the older sample in M51, the lack of tight correlations is probably due to the combination of strong azimuthal variations in the surface densities of gas and star formation rate, and the cluster ages. These two facts mean that neither the azimuthal average of the surface densities at a given radius nor the surface densities at the present-day location of a stellar cluster represent the true surface densities at the place and time of cluster formation. In the case of the younger sample, even if the clusters have not yet

  12. Influence of size and density on filtration rate modeling and nutrient uptake by green mussel (Perna viridis).

    Science.gov (United States)

    Tantanasarit, Chayarat; Babel, Sandhya; Englande, Andrew J; Meksumpun, Shettapong

    2013-03-15

    This study investigates green mussel filtration rates based on variation of the mussel size and density, and attempts to correlate these with the amount of Chaetoceros calcitrans consumed by kinetic modeling. The filtration rates were found to be more effective in small mussels and with greater volumes of seawater/mussel which represent low mussel densities in the mussel farms. Under field condition, the first order kinetic model is useful for evaluation of mussel filtration rate. However, the composite exponential kinetic model was determined to better describe filtration rates in a close system. Higher ratios of seawater volume L/g DW mussel tissue, resulted in an increasing filtration rate until a maximum plateau was reached at 10.37 L/h/g DW tissue as determined by first order kinetics. Based on the filtration rate, carbon, nitrogen, and phosphorus uptake by green mussels were found to be 2128.72, 265.41, and 66.67 mg/year/indv, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Maize response to elevated plant density combined with lowered N-fertilizer rate is genotype-dependent

    Institute of Scientific and Technical Information of China (English)

    Ahmed; Medhat; M.Al-Naggar; Reda; A.Shabana; Mohamed; M.M.Atta; Tarek; H.Al-Khalil

    2015-01-01

    Increasing plant density and improving N fertilizer rate along with the use of high density-tolerant genotypes would lead to maximizing maize(Zea mays L.) grain productivity per unit land area. The objective of this investigation was to match the functions of optimum plant density and adequate nitrogen fertilizer application to produce the highest possible yields per unit area with the greatest maize genotype efficiency. Six maize inbred lines differing in tolerance to low N and high density(D) [three tolerant(T); L-17, L-18, L-53,and three sensitive(S); L-29, L-54, L-55] were chosen for diallel crosses. Parents and crosses were evaluated in the 2012 and 2013 seasons under three plant densities: low(47,600),medium(71,400), and high(95,200) plants ha-1and three N fertilization rates: low(no N addition), medium(285 kg N ha-1) and high(570 kg N ha-1). The T × T crosses were superior to the S × S and T × S crosses under the low N–high D environment in most studied traits across seasons. The relationships between the nine environments and grain yield per hectare(GYPH) showed near-linear regression functions for inbreds L54, L29, and L55 and hybrids L18 × L53 and L18 × L55 with the highest GYPH at a density of47,600 plants ha-1and N rate of 570 kg N ha-1and a curvilinear relationship for inbreds L17, L18, and L53 and the rest of the hybrids with the highest GYPH at a density of95,200 plants ha-1combined with an N rate of 570 kg N ha-1. Cross L17 × L54 gave the highest grain yield in this study under both high N–high-D(19.9 t ha-1) and medium N–high-D environments(17.6 t ha-1).

  14. Improved results in proteomics by use of local and peptide-class specific false discovery rates

    Directory of Open Access Journals (Sweden)

    Bukowski-Wills Jimi-Carlo

    2009-06-01

    Full Text Available Abstract Background Proteomic protein identification results need to be compared across laboratories and platforms, and thus a reliable method is needed to estimate false discovery rates. The target-decoy strategy is a platform-independent and thus a prime candidate for standardized reporting of data. In its current usage based on global population parameters, the method does not utilize individual peptide scores optimally. Results Here we show that proteomic analyses largely benefit from using separate treatment of peptides matching to proteins alone or in groups based on locally estimated false discovery rates. Our implementation reduces the number of false positives and simultaneously increases the number of proteins identified. Importantly, single peptide identifications achieve defined confidence and the sequence coverage of proteins is optimized. As a result, we improve the number of proteins identified in a human serum analysis by 58% without compromising identification confidence. Conclusion We show that proteins can reliably be identified with a single peptide and the sequence coverage for multi-peptide proteins can be increased when using an improved estimation of false discovery rates.

  15. Concomitant cervical and transperineal parametrial high-dose-rate brachytherapy boost for locally advanced cervical cancer

    Directory of Open Access Journals (Sweden)

    Caroline Bailleux

    2016-01-01

    Full Text Available Purpose: There is no consensus for parametrial boost technic while both transvaginal and transperineal approaches are discussed. A prototype was developed consisting of a perineal template, allowing transperineal needle insertion. This study analyzed acute toxicity of concomitant cervical and transperineal parametrial high-dose-rate brachytherapy (HDRB boost for locally advanced cervical cancer. Material and methods: From 01.2011 to 12.2014, 33 patients (pts presenting a locally advanced cervical cancer with parametrial invasion were treated. After the first course of external beam radiation therapy with cisplatinum, HDRB was performed combining endocavitary and interstitial technique for cervical and parametrial disease. Post-operative delineation (CTV, bladder, rectum, sigmoid and planification were based on CT-scan/MRI. HDRB was delivered in 3-5 fractions over 2-3 consecutive days. Acute toxicities occurring within 6 months after HDRB were retrospectively reviewed. Results: Median age was 56.4 years (27-79. Clinical stages were: T2b = 23 pts (69.7%, T3a = 1 pt (3%, T3b = 6 pts (18.2%, and T4a = 3 pts (9.1%. Median HDRB prescribed dose was 21 Gy (21-27. Median CTVCT (16 pts and HR-CTV MRI (17 pts were 52.6 cc (28.5-74.3, 31.9 cc (17.1-58, respectively. Median EQD2αβ10 for D90CTV and D90HR-CTV were 82.9 Gy (78.2-96.5, 84.8 Gy (80.6-91.4, respectively. Median EQD2αβ3 (CT/MRI for D2cc bladder, rectum and sigmoid were 75.5 Gy (66.6-90.9, 64.4 Gy (51.9-77.4, and 60.4 Gy (50.9-81.1, respectively. Median follow-up was 14 months (ranged 6-51. Among the 24 pts with MFU = 24 months, 2-year LRFS rate, RRFS, and OS were 86.8%, 88.8%, and 94.1%, respectively. The rates of acute genitourinary and gastrointestinal toxicities were 36% (G1 dysuria = 8 pts, G2 infection = 2 pt, G3 infection = 2 pts, and 27% (G1 diarrhea = 9 pts, respectively. One patient presented vaginal bleeding at the time of applicator withdrawal (G3-blood transfusion; no bleeding was

  16. MnO2-Carbon nanotube composite for high-areal-density supercapacitors with high rate performance

    Science.gov (United States)

    Wang, Ke; Gao, Shan; Du, Zhaolong; Yuan, Anbao; Lu, Wei; Chen, Liwei

    2016-02-01

    Practical supercapacitor devices require high areal capacitance and areal power density, and thus demand high utilization of active material and good rate performance under high areal mass loading. However, ion transport in high-mass-loading electrodes can be a challenge, which leads to deteriorate specific capacitance and rate performance. In this paper, a well-dispersed porous MnO2-carbon nanotube (CNT) composite was prepared for use as a supercapacitor electrode material. The small MnO2 nanoparticles and porous CNT network facilitated fast electron/ion transfer kinetics in the electrode. With a mass loading as high as 6.4 mg cm-2 on the electrode, the MnO2-CNT composite exhibited an excellent areal capacitance of 1.0 F cm-2 at 0.2 A g-1 (1.28 mA cm-2), with a retention of 77% even at a high current density of 20 A g-1 (128 mA cm-2). The electrode exhibited a high power density of 45.2 kW kg-1 (0.29 W cm-2) while maintaining a reasonable energy density of 16.7 Wh kg-1 (106 μWh cm-2). No apparent fading was observed even after 3000 charge/discharge cycles at 1 A g-1. This porous and evenly distributed MnO2-CNT composite has great potential for practical applications in supercapacitors.

  17. Coulomb correlation effects and density dependence of radiative recombination rates in polar AlGaN quantum wells

    Science.gov (United States)

    Rupper, Greg; Rudin, Sergey; Bertazzi, Francesco; Garrett, Gregory; Wraback, Michael

    2013-03-01

    AlGaN narrow quantum wells are important elements of deep-ultraviolet light emitting devices. The electron-hole radiative recombination rates are important characteristics of these nanostructures. In this work we evaluated their dependence on carrier density and lattice temperature and compared our theoretical results with the experimentally determined radiative lifetimes in the c-plane grown AlGaN quantum wells. The bands were determined in the k .p approximation for a strained c-plane wurtzite quantum well and polarization fields were included in the model. In order to account for Coulomb correlations at relatively high densities of photo-excited electron-hole plasma and arbitrary temperature, we employed real-time Green's function formalism with self-energies evaluated in the self-consistent T-matrix approximation. The luminescence spectrum was obtained from the susceptibility by summing over scattering in-plane directions and polarization states. The recombination coefficient was obtained from the integrated photo-luminescence. The density dependence of the radiative recombination rate shows effects of strong screening of the polarization electric field at high photo-excitation density.

  18. Carrier-density dependence of photoluminescence from localized states in InGaN/GaN quantum wells in nanocolumns and a thin film

    Energy Technology Data Exchange (ETDEWEB)

    Shimosako, N., E-mail: n-shimosako@sophia.jp; Inose, Y.; Satoh, H.; Kinjo, K.; Nakaoka, T.; Oto, T. [Department of Engineering and Applied Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Kishino, K.; Ema, K. [Department of Engineering and Applied Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Sophia Nanotechnology Research Center, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan)

    2015-11-07

    We have measured and analyzed the carrier-density dependence of photoluminescence (PL) spectra and the PL efficiency of InGaN/GaN multiple quantum wells in nanocolumns and in a thin film over a wide excitation range. The localized states parameters, such as the tailing parameter, density and size of the localized states, and the mobility edge density are estimated. The spectral change and reduction of PL efficiency are explained by filling of the localized states and population into the extended states around the mobility edge density. We have also found that the nanocolumns have a narrower distribution of the localized states and a higher PL efficiency than those of the film sample although the In composition of the nanocolumns is higher than that of the film.

  19. Weavable, Conductive Yarn-Based NiCo//Zn Textile Battery with High Energy Density and Rate Capability.

    Science.gov (United States)

    Huang, Yan; Ip, Wing Shan; Lau, Yuen Ying; Sun, Jinfeng; Zeng, Jie; Yeung, Nga Sze Sea; Ng, Wing Sum; Li, Hongfei; Pei, Zengxia; Xue, Qi; Wang, Yukun; Yu, Jie; Hu, Hong; Zhi, Chunyi

    2017-09-26

    With intrinsic safety and much higher energy densities than supercapacitors, rechargeable nickel/cobalt-zinc-based textile batteries are promising power sources for next generation personalized wearable electronics. However, high-performance wearable nickel/cobalt-zinc-based batteries are rarely reported because there is a lack of industrially weavable and knittable highly conductive yarns. Here, we use scalably produced highly conductive yarns uniformly covered with zinc (as anode) and nickel cobalt hydroxide nanosheets (as cathode) to fabricate rechargeable yarn batteries. They possess a battery level capacity and energy density, as well as a supercapacitor level power density. They deliver high specific capacity of 5 mAh cm(-3) and energy densities of 0.12 mWh cm(-2) and 8 mWh cm(-3) (based on the whole solid battery). They exhibit ultrahigh rate capabilities of 232 C (liquid electrolyte) and 116 C (solid electrolyte), which endows the batteries excellent power densities of 32.8 mW cm(-2) and 2.2 W cm(-3) (based on the whole solid battery). These are among the highest values reported so far. A wrist band battery is further constructed by using a large conductive cloth woven from the conductive yarns by a commercial weaving machine. It powers various electronic devices successfully, enabling dual functions of wearability and energy storage.

  20. Immobilization of bilirubin oxidase on graphene oxide flakes with different negative charge density for oxygen reduction. The effect of GO charge density on enzyme coverage, electron transfer rate and current density.

    Science.gov (United States)

    Filip, Jaroslav; Andicsová-Eckstein, Anita; Vikartovská, Alica; Tkac, Jan

    2017-03-15

    Previously we showed that an effective bilirubin oxidase (BOD)-based biocathode using graphene oxide (GO) could be prepared in 2 steps: 1. electrostatic adsorption of BOD on GO; 2. electrochemical reduction of the BOD-GO composite to form a BOD-ErGO (electrochemically reduced GO) film on the electrode. In order to identify an optimal charge density of GO for BOD-ErGO composite preparation, several GO fractions differing in an average flake size and ζ-potential were prepared using centrifugation and consequently employed for BOD-ErGO biocathode preparation. A simple way to express surface charge density of these particular GO nanosheets was developed. The values obtained were then correlated with biocatalytic and electrochemical parameters of the prepared biocathodes, i.e. electrocatalytically active BOD surface coverage (Γ), heterogeneous electron transfer rate (kS) and a maximum biocatalytic current density. The highest bioelectrocatalytic current density of (597±25)μAcm(-2) and the highest Γ of (23.6±0.9)pmolcm(-2) were obtained on BOD-GO composite having the same moderate negative charge density, but the highest kS of (79.4±4.6)s(-1) was observed on BOD-GO composite having different negative charge density. This study is a solid foundation for others to consider the influence of a charge density of GO on direct bioelectrochemistry/bioelectrocatalysis of other redox enzymes applicable for construction of biosensors, bioanodes, biocathodes or biofuel cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Superemitters in Hybrid Photonic Systems: A Simple Lumping Rule for the Local Density of Optical States and its Break-Down at the Unitary Limit

    CERN Document Server

    Frimmer, Martin

    2012-01-01

    We theoretically investigate how the enhancement of the radiative decay rate of a spontaneous emitter provided by coupling to an optical antenna is modified when this "superemitter" is introduced into a complex photonic environment that provides an enhanced local density of optical states (LDOS) itself, such as a microcavity. We show that photonic environments with increased LDOS further boost the performance of antennas that scatter weakly, i.e. that are far from the unitary limit, for which a simple multiplicative LDOS lumping rule holds. In contrast, enhancements provided by antennas close to the unitary limit, i.e. antennas close to the limit of maximally possible scattering strength, are strongly reduced by an enhanced LDOS of the environment. Thus, we identify multiple scattering in hybrid photonic systems as a powerful mechanism for LDOS engineering.

  2. Local conservation scores without a priori assumptions on neutral substitution rates

    Directory of Open Access Journals (Sweden)

    Hagenauer Joachim

    2008-04-01

    Full Text Available Abstract Background Comparative genomics aims to detect signals of evolutionary conservation as an indicator of functional constraint. Surprisingly, results of the ENCODE project revealed that about half of the experimentally verified functional elements found in non-coding DNA were classified as unconstrained by computational predictions. Following this observation, it has been hypothesized that this may be partly explained by biased estimates on neutral evolutionary rates used by existing sequence conservation metrics. All methods we are aware of rely on a comparison with the neutral rate and conservation is estimated by measuring the deviation of a particular genomic region from this rate. Consequently, it is a reasonable assumption that inaccurate neutral rate estimates may lead to biased conservation and constraint estimates. Results We propose a conservation signal that is produced by local Maximum Likelihood estimation of evolutionary parameters using an optimized sliding window and present a Kullback-Leibler projection that allows multiple different estimated parameters to be transformed into a conservation measure. This conservation measure does not rely on assumptions about neutral evolutionary substitution rates and little a priori assumptions on the properties of the conserved regions are imposed. We show the accuracy of our approach (KuLCons on synthetic data and compare it to the scores generated by state-of-the-art methods (phastCons, GERP, SCONE in an ENCODE region. We find that KuLCons is most often in agreement with the conservation/constraint signatures detected by GERP and SCONE while qualitatively very different patterns from phastCons are observed. Opposed to standard methods KuLCons can be extended to more complex evolutionary models, e.g. taking insertion and deletion events into account and corresponding results show that scores obtained under this model can diverge significantly from scores using the simpler model

  3. Economic and Environmental Impacts of Improving Growth Rate and Feed Efficiency in Fish Farming Depend on Nitrogen and Density Limitation

    OpenAIRE

    Besson, M.; Komen, H.; Vandeputte, M.; Aubin, J.; Boer, De; van Arendonk,

    2014-01-01

    The aim of fish breeding is to increase profit by producing faster growing fish with lower feed intake. However, little is known about the economic and environmental impacts of selective breeding programs for fish. We modelled a fish farm producing African catfish in a Recirculating Aquaculture System (RAS) to calculate economic values of growth rate and feed efficiency with production limited by fish density in rearing tanks and fish nitrogen emission. We also calculated “environmental value...

  4. Preoperative Erythrocyte Sedimentation Rate Independently Predicts Overall Survival in Localized Renal Cell Carcinoma following Radical Nephrectomy

    Directory of Open Access Journals (Sweden)

    Brian W. Cross

    2012-01-01

    Full Text Available Objectives. To determine the relationship between preoperative erythrocyte sedimentation rate (ESR and overall survival in localized renal cell carcinoma (RCC following nephrectomy. Methods. 167 patients undergoing nephrectomy for localized RCC had ESR levels measured preoperatively. Receiver Operating Characteristics curves were used to determine Area Under the Curve and relative sensitivity and specificity of preoperative ESR in predicting overall survival. Cut-offs for low (0.0–20.0 mm/hr, intermediate (20.1–50.0 mm/hr, and high risk (>50.0 mm/hr groups were created. Kaplan-Meier analysis was conducted to assess the univariate impact of these ESR-based groups on overall survival. Univariate and multivariate Cox regression analysis was conducted to assess the potential of these groups to predict overall survival, adjusting for other patient and tumor characteristics. Results. Overall, 55.2% were low risk, while 27.0% and 17.8% were intermediate and high risk, respectively. Median (95% CI survival was 44.1 (42.6–45.5 months, 35.5 (32.3–38.8 months, and 32.1 (25.5–38.6 months, respectively. After controlling for other patient and tumor characteristics, intermediate and high risk groups experienced a 4.5-fold (HR: 4.509, 95% CI: 0.735–27.649 and 18.5-fold (HR: 18.531, 95% CI: 2.117–162.228 increased risk of overall mortality, respectively. Conclusion. Preoperative ESR values represent a robust predictor of overall survival following nephrectomy in localized RCC.

  5. Prognosticating fault development rate in wind turbine generator bearings using local trend models

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Palou, Jonel; Sweeney, Christian Walsted;

    2016-01-01

    Generator bearing defects, e.g. ball, inner and outer race defects, are ranked among the most frequent mechanical failures encountered in wind turbines. Diagnosis and prognosis of bearing faults can be successfully implemented using vibration based condition monitoring systems, where tracking...... the signal energy between 10Hz to 1000Hz is utilized as feature to characterize the severity of developing bearing faults. Furthermore, local trend models are employed to predict the progression of bearing defects from a vibration standpoint in accordance with the limits suggested in ISO 10816. Predictions...... of vibration trends from multi-megawatt wind turbine generators are presented, showing the effectiveness of the suggested approach on the calculation of the RUL and fault progression rate....

  6. Local Entropy Production Rates in a Polymer Electrolyte Membrane Fuel Cell

    Science.gov (United States)

    Siemer, Marc; Marquardt, Tobias; Valadez Huerta, Gerardo; Kabelac, Stephan

    2017-01-01

    A modeling study on a polymer electrolyte membrane fuel cell by means of non-equilibrium thermodynamics is presented. The developed model considers a one-dimensional cell in steady-state operation. The temperature, concentration and electric potential profiles are calculated for every domain of the cell. While the gas diffusion and the catalyst layers are calculated with established classical modeling approaches, the transport processes in the membrane are calculated with the phenomenological equations as dictated by the non-equilibrium thermodynamics. This approach is especially instructive for the membrane as the coupled transport mechanisms are dominant. The needed phenomenological coefficients are approximated on the base of conventional transport coefficients. Knowing the fluxes and their intrinsic corresponding forces, the local entropy production rate is calculated. Accordingly, the different loss mechanisms can be detected and quantified, which is important for cell and stack optimization.

  7. Global existence of solutions to a tear film model with locally elevated evaporation rates

    Science.gov (United States)

    Gao, Yuan; Ji, Hangjie; Liu, Jian-Guo; Witelski, Thomas P.

    2017-07-01

    Motivated by a model proposed by Peng et al. (2014) for break-up of tear films on human eyes, we study the dynamics of a generalized thin film model. The governing equations form a fourth-order coupled system of nonlinear parabolic PDEs for the film thickness and salt concentration subject to non-conservative effects representing evaporation. We analytically prove the global existence of solutions to this model with mobility exponents in several different ranges and present numerical simulations that are in agreement with the analytic results. We also numerically capture other interesting dynamics of the model, including finite-time rupture-shock phenomenon due to the instabilities caused by locally elevated evaporation rates, convergence to equilibrium and infinite-time thinning.

  8. Theoretical and numerical study of strain localization under high strain rate solicitation

    Science.gov (United States)

    Ranc, N.; Raynal, R.; Taravella, L.; Pina, V.; Hervé, P.

    2006-08-01

    Our study deals with the dynamic behavior of metallic materials and in particular of titanium alloy TA6V. For high strain rates, we can notice the occurrence of a phenomenon called adiabatic shearing. This phenomenon is about a plastic instability, which results in the appearance of a strain localization in narrow bands. In this paper we developed a thermo mechanical model to reproduce the formation and the propagation of adiabatic shear bands. A Johnson Cook thermo visco plastic behavior law was chosen for the titanium alloy TA6V. The law parameters were identified from static and dynamic torsion tests at various temperatures between ambient and 350circC. A 2D numerical simulation of torsion test was performed with the explicit finite elements code Abaqus. The thermo mechanical coupling and the heat conduction are taken into account. A roughness defect was inserted in the centre of a torsion specimen. The results showed that the strain of localization and the shear band speed increase when the amplitude and the size of the defect decrease.

  9. Diet density in rearing and reproductive phases influences carcass composition, pregnancy rate and litter performance of primiparous rabbit does

    Directory of Open Access Journals (Sweden)

    Paulo Sérgio dos Santos Teixeira

    2017-06-01

    Full Text Available The objective was to evaluate the effect of the interaction of diet density in the rearing phase×diet density in the reproductive phase on carcass composition, pregnancy rate, and litter performance of primiparous rabbit does. The experiment followed a 2×2×2 factorial (2 seasons, 2 diet densities in the rearing phase and 2 diet densities in reproductive phase, that is, from mating to weaning of the first litter. The reference diet (RD contained 184 g/kg of crude protein (CP, 165 g/kg of acid detergent fibre (ADF and 10.5 MJ/kg of digestible energy (DE. The low-density diet (LD had 147 g/kg of CP, 24 g/kg of ADF and 8.4 MJ/kg of DE. The treatments were applied from 70 d of age until weaning of the first litter at 35 d of age. Ninety-six females from the Botucatu Genetic Group (24 females/experimental group were mated at 142 d of age. On day 12 of gestation, 23 does were slaughtered to evaluate weights of carcass, organs and dissectible fat, and embryo implantation rate. No effects of diet density in the rearing or in the reproductive phases were detected on feed intake of does during the reproductive phase. Does fed LD during the rearing phase showed lower body weight at mating (3574±47 vs. 3866±43 g, P=0.0001 and during most of the reproductive phase, but they lost less weight in the peripartum. Perirenal fat was lighter in these does (72.8±10.0 vs. 102.1±9.6 g, P=0.048 and they showed a lower pregnancy rate (76.1 vs. 91.7%, P=0.045. The does fed RD in the reproductive phase were heavier during this phase (4055±40 g vs. 3887±41 g, P=0.0044. The does fed LD in rearing phase and RD in the reproductive phase showed larger litters at weaning, due to decreased kit mortality, than those fed RD in both phases (6.16±0.47 vs. 3.93±0.71, P=0.0361. Litters were lighter at weaning when LD was fed in the reproductive phase (3582±201 vs. 4733±187, P<0.0001. Feeding a low-density diet during the rearing phase and a reference diet during the

  10. Gas surface density, star formation rate surface density, and the maximum mass of young star clusters in a disk galaxy. I. The flocculent galaxy M33

    CERN Document Server

    Gonzalez-Lopezlira, Rosa A; Kroupa, Pavel

    2012-01-01

    We analyze the relationship between maximum cluster mass, M_max, and surface densities of total gas (Sigma_gas), molecular gas (Sigma_H2) and star formation rate (Sigma_SFR) in the flocculent galaxy M33, using published gas data and a catalog of more than 600 young star clusters in its disk. By comparing the radial distributions of gas and most massive cluster masses, we find that M_max is proportional to Sigma_gas^4.7, M_max is proportional Sigma_H2^1.3, and M_max is proportional to Sigma_SFR^1.0. We rule out that these correlations result from the size of sample; hence, the change of the maximum cluster mass must be due to physical causes.

  11. Combined local-density and dynamical mean field theory calculations for the compressed lanthanides Ce, Pr, and Nd

    Energy Technology Data Exchange (ETDEWEB)

    McMahan, A K

    2005-03-30

    This paper reports calculations for compressed Ce (4f{sup 1}), Pr (4f{sup 2}), and Nd (4f{sup 3}) using a combination of the local-density approximation (LDA) and dynamical mean field theory (DMFT), or LDA+DMFT. The 4f moment, spectra, and the total energy among other properties are examined as functions of volume and atomic number for an assumed face-centered cubic (fcc) structure. These materials are seen to be strongly localized at ambient pressure and for compressions up through the experimentally observed fcc phases ({gamma} phase for Ce), in the sense of having fully formed Hund's rules moments and little 4f spectral weight at the Fermi level. Subsequent compression for all three lanthanides brings about significant deviation of the moments from their Hund's rules values, a growing Kondo resonance at the fermi level, an associated softening in the total energy, and quenching of the spin orbit since the Kondo resonance is of mixed spin-orbit character while the lower Hubbard band is predominantly j = 5/2. while the most dramatic changes for Ce occur within the two-phase region of the {gamma}-{alpha} volume collapse transition, as found in earlier work, those for Pr and Nd occur within the volume range of the experimentally observed distorted fcc (dfcc) phase, which is therefore seen here as transitional and not part of the localized trivalent lanthanide sequence. The experimentally observed collapse to the {alpha}-U structure in Pr occurs only on further compression, and no such collapse is found in Nd. These lanthanides start closer to the localized limit for increasing atomic number, and so the theoretical signatures noted above are also offset to smaller volume as well, which is possibly related to the measured systematics of the size of the volume collapse being 15%, 9%, and none for Ce, Pr, and Nd, respectively.

  12. LOCAL-DENSITY FUNCTIONAL AND ON-SITE CORRELATIONS - THE ELECTRONIC-STRUCTURE OF LA2CUO4 AND LACUO3

    NARCIS (Netherlands)

    CZYZYK, MT; SAWATZKY, GA

    1994-01-01

    State-of-the-art electronic-structure calculations based on the local-density approximation (LDA) to the density functional fail to reproduce the insulating antiferromagnetic ground state in the parent compounds of the high-temperature oxide superconductors. Similar problems have been observed earli

  13. No experimental evidence for local competition in the nestling phase as a driving force for density-dependent avian clutch size

    NARCIS (Netherlands)

    Nicolaus, Marion; Both, Christiaan; Ubels, Richard; Edelaar, Pim; Tinbergen, Joost M.; Butler, Simon

    2009-01-01

    In birds, local competition for food between pairs during the nestling phase may affect nestling growth and survival. A decrease in clutch size with an increase in breeding density could be an adaptive response to this competition. To investigate whether breeding density causally affected the clutch

  14. The relation between surface star formation rate density and spiral arms in NGC 5236 (M83)

    CERN Document Server

    Silva-Villa, Esteban

    2011-01-01

    For a long time the consensus has been that star formation rates are higher in the interior of spiral arms in galaxies, compared to inter-arm regions. However, recent studies have found that the star formation inside the arms is not more efficient than elsewhere in the galaxy. Previous studies have based their conclusion mainly on integrated light. We use resolved stellar populations to investigate the star formation rates throughout the nearby spiral galaxy NGC 5236. We aim to investigate how the star formation rate varies in the spiral arms compared to the inter-arm regions, using optical space-based observations of NGC 5236. Using ground-based H\\alpha images we traced regions of recent star formation, and reconstructed the arms of the galaxy. Using HST/ACS images we estimate star formation histories by means of the synthetic CMD method. Arms based on H\\alpha images showed to follow the regions where stellar crowding is higher. Star formation rates for individual arms over the fields covered were estimated ...

  15. Estimating rates of local species extinction, colonization and turnover in animal communities

    Science.gov (United States)

    Nichols, James D.; Boulinier, T.; Hines, J.E.; Pollock, K.H.; Sauer, J.R.

    1998-01-01

    Species richness has been identified as a useful state variable for conservation and management purposes. Changes in richness over time provide a basis for predicting and evaluating community responses to management, to natural disturbance, and to changes in factors such as community composition (e.g., the removal of a keystone species). Probabilistic capture-recapture models have been used recently to estimate species richness from species count and presence-absence data. These models do not require the common assumption that all species are detected in sampling efforts. We extend this approach to the development of estimators useful for studying the vital rates responsible for changes in animal communities over time; rates of local species extinction, turnover, and colonization. Our approach to estimation is based on capture-recapture models for closed animal populations that permit heterogeneity in detection probabilities among the different species in the sampled community. We have developed a computer program, COMDYN, to compute many of these estimators and associated bootstrap variances. Analyses using data from the North American Breeding Bird Survey (BBS) suggested that the estimators performed reasonably well. We recommend estimators based on probabilistic modeling for future work on community responses to management efforts as well as on basic questions about community dynamics.

  16. Basic theories for strain localization analysis of porous media with rate dependent model

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hongwu; QIN Jianmin

    2005-01-01

    This paper analyzes the interaction between two kinds of internal length scales when the rate dependent plasticity is introduced to a multiphase material model to study the dynamic strain localization phenomenon of saturated and partially saturated porous media. The stability analysis demonstrates that the enhanced porous media model preserves the well-posedness of the initial value problem for both axial and shear waves because an internal length scale parameter is introduced in the visco-plasticity model. On the other hand, the interaction between the length scale introduced by the rate dependent model and that naturally contained in the governing equations of fully and partially saturated model will take place. A basic method is presented to investigate the internal length scale of the multiphase porous media under the interaction of these two kinds of length scale parameters. Material stability analysis is carried out for a certain permeability from which the results of wave number domain with real wave speed are distinguished. A one dimensional example is given to illustrate the theoretical findings.

  17. Kerfdr: a semi-parametric kernel-based approach to local false discovery rate estimation

    Directory of Open Access Journals (Sweden)

    Robin Stephane

    2009-03-01

    Full Text Available Abstract Background The use of current high-throughput genetic, genomic and post-genomic data leads to the simultaneous evaluation of a large number of statistical hypothesis and, at the same time, to the multiple-testing problem. As an alternative to the too conservative Family-Wise Error-Rate (FWER, the False Discovery Rate (FDR has appeared for the last ten years as more appropriate to handle this problem. However one drawback of FDR is related to a given rejection region for the considered statistics, attributing the same value to those that are close to the boundary and those that are not. As a result, the local FDR has been recently proposed to quantify the specific probability for a given null hypothesis to be true. Results In this context we present a semi-parametric approach based on kernel estimators which is applied to different high-throughput biological data such as patterns in DNA sequences, genes expression and genome-wide association studies. Conclusion The proposed method has the practical advantages, over existing approaches, to consider complex heterogeneities in the alternative hypothesis, to take into account prior information (from an expert judgment or previous studies by allowing a semi-supervised mode, and to deal with truncated distributions such as those obtained in Monte-Carlo simulations. This method has been implemented and is available through the R package kerfdr via the CRAN or at http://stat.genopole.cnrs.fr/software/kerfdr.

  18. The Star Formation Rate-Density Relation at 0.6

    CERN Document Server

    Patel, Shannon G; Holden, Bradford P; Franx, Marijn; Illingworth, Garth D

    2011-01-01

    We study the star formation rates (SFRs) of galaxies as a function of local galaxy density at 0.61.8x10^{10} Msun to conduct our main analysis. With three different SFR indicators, (1) Spitzer MIPS 24-micron imaging, (2) SED fitting, and (3) [OII]3727 emission, we find the median specific SFR (SSFR) and SFR to decline from the low-density field to the cores of groups and a rich cluster. For the SED and [OII] based SFRs, the decline in SSFR is roughly an order of magnitude while for the MIPS based SFRs, the decline is a factor of ~4. We find approximately the same magnitude of decline in SSFR even after removing the sample of galaxies near the cluster. Galaxies in groups and a cluster at these redshifts therefore have lower star formation (SF) activity than galaxies in the field, as is the case at z~0. We investigated whether the decline in SFR with increasing density is caused by a change in the proportion of quiescent and star forming galaxies (SFGs) or by a decline in the SFRs of SFGs. Using the rest-frame ...

  19. Three-dimensional integral equation approach to light scattering, extinction cross sections, local density of states and quasinormal modes

    CERN Document Server

    de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst

    2013-01-01

    We present a numerical formalism for solving the Lippmann-Schwinger equation for the electric field in three dimensions. The formalism may be applied to scatterers of different shapes and embedded in different background media, and we develop it in detail for the specific case of spherical scatterers in a homogeneous background medium. In addition, we show how several physically important quantities may readily be calculated with the formalism. These quantities include the extinction cross section, the total Green's tensor, the projected local density of states and the Purcell factor as well as the quasinormal modes of leaky resonators with the associated resonance frequencies and quality factors. We demonstrate the calculations for the well-known plasmonic dimer consisting of two silver nanoparticles and thus illustrate the versatility of the formalism for use in modeling of advanced nanophotonic devices.

  20. Large-eddy simulation/probability density function modeling of local extinction and re-ignition in Sandia Flame E

    Science.gov (United States)

    Wang, Haifeng; Popov, Pavel; Hiremath, Varun; Lantz, Steven; Viswanathan, Sharadha; Pope, Stephen

    2010-11-01

    A large-eddy simulation (LES)/probability density function (PDF) code is developed and applied to the study of local extinction and re-ignition in Sandia Flame E. The modified Curl mixing model is used to account for the sub-filter scalar mixing; the ARM1 mechanism is used for the chemical reaction; and the in- situ adaptive tabulation (ISAT) algorithm is used to accelerate the chemistry calculations. Calculations are performed on different grids to study the resolution requirement for this flame. Then, with sufficient grid resolution, full-scale LES/PDF calculations are performed to study the flame characteristics and the turbulence-chemistry interactions. Sensitivity to the mixing frequency model is explored in order to understand the behavior of sub-filter scalar mixing in the context of LES. The simulation results are compared to the experimental data to demonstrate the capability of the code. Comparison is also made to previous RANS/PDF simulations.

  1. Complex Orbitals, Multiple Local Minima, and Symmetry Breaking in Perdew-Zunger Self-Interaction Corrected Density Functional Theory Calculations.

    Science.gov (United States)

    Lehtola, Susi; Head-Gordon, Martin; Jónsson, Hannes

    2016-07-12

    Implentation of seminumerical stability analysis for calculations using the Perdew-Zunger self-interaction correction is described. It is shown that real-valued solutions of the Perdew-Zunger equations for gas phase atoms are unstable with respect to imaginary orbital rotations, confirming that a proper implementation of the correction requires complex-valued orbitals. The orbital density dependence of the self-interaction corrected functional is found to lead to multiple local minima in the case of the acrylic acid, H6, and benzene molecules. In the case of benzene, symmetry breaking that results in incorrect ground state geometry is found to occur, erroneously leading to alternating bond lengths in the molecule.

  2. Identifying the role of the local density of optical states in frequency conversion of light in a microcavity

    CERN Document Server

    Yüce, Emre; Claudon, Julien; Gérard, Jean-Michel; Vos, Willem L

    2014-01-01

    We have reversibly switched the resonance of a GaAs-AlAs microcavity in the near-infrared near $\\lambda =1300$ nm within 300 fs by the electronic Kerr effect. We reveal by pump-probe spectroscopy a remarkable red shift or blue shift of the light confined inside the cavity for small pulse delays, depending on their temporal ordering. The color-converted light is efficiently generated in a broad frequency continuum that differs markedly from the instantaneous cavity resonance in terms of the central frequency and bandwidth. From observations on cavities with different quality factors, we identify the role of the local density of optical states (LDOS) available to the newly generated light frequencies. In particular, we distinguish the effect of the LDOS related to the cavity resonance itself, and the LDOS continuum that leaks in from the vacuum surrounding the cavity. Our new insights provide a unified picture for seemingly disparate results in traditional and nanophotonic nonlinear optics.

  3. Filtration of interstellar hydrogen in the two-shock heliospheric interface Inferences on the local interstellar electron density

    CERN Document Server

    Izmodenov, V V; Lallement, R; Glöckler, G; Baranov, V B; Malama, Y G

    1998-01-01

    The solar system is moving through the partially ionized local interstellar cloud (LIC). The ionized matter of the LIC interacts with the expanding solar wind forming the heliospheric interface. The neutral component (interstellar atoms) penetrates through the heliospheric interface into the heliosphere, where it is measured directly "in situ" as pick-up ions and neutral atoms (and as anomalous cosmic rays) or indirectly through resonant scattering of solar Ly-alpha. When crossing the heliospheric interface, interstellar atoms interact with the plasma component through charge exchange. This interaction leads to changes of both neutral gas and plasma properties. The heliospheric interface is also the source of radio emissions which have been detected by the Voyager since 1983. In this paper, we have used a kinetic model of the flow of the interstellar atoms with updated values of velocity, temperature, and density of the circumsolar interstellar hydrogen and calculated how all quantities which are directly ass...

  4. Semianalytical quasi-normal mode theory for the local density of states in coupled photonic crystal cavity-waveguide structures.

    Science.gov (United States)

    de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper; Gregersen, Niels

    2015-12-15

    We present and validate a semianalytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities, a nontrivial spectrum with a peak and a dip is found, which is reproduced only when including both the two relevant QNMs in the theory. In both cases, we find relative errors below 1% in the bandwidth of interest.

  5. Study delay and dispersion effects in dynamic susceptibility contrast MRI based on local density random walk distribution

    Science.gov (United States)

    Li, Xingfeng; Tian, Jie; Wang, Xiaoxiang; Dai, Jianping; Ai, Lin

    2004-04-01

    The aim of this study was to assess the validation of the local density random walk (LDRW) function to correct the delayed and dispersed arterial input function (AIF) data derived from dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI). Instead of using the gamma-variate function to smooth and extrapolate the AIF curves, we suggested a method which was based on diffusion with drift approach. Forty-seven AIF curves from ten patients were segmented to test the effectiveness of the proposed method. The results of the comparisons with the gamma-variate function showed that the LDRW distribution function may provide a new means for more accurate correction of AIF curves.

  6. Local density of states study of a spin-orbit-coupling induced Mott insulator Sr2IrO4

    Science.gov (United States)

    Dai, Jixia; Calleja, Eduardo; Cao, Gang; McElroy, Kyle

    2014-07-01

    We present scanning tunneling microscopy and spectroscopy experiments on the novel Jeff=1/2 Mott insulator Sr2IrO4. Local density of states (LDOS) measurements show an intrinsic insulating gap of 620 meV that is asymmetric about the Fermi level and is larger than previously reported values. The size of this gap suggests that Sr2IrO4 is likely a Mott rather than Slater insulator. In addition, we found a small number of native defects which create in-gap spectral weight. Atomically resolved LDOS measurements on and off the defects show that this energy gap is quite fragile. Together the extended nature of the 5d electrons and poor screening of defects help explain the elusive nature of this gap.

  7. Fast design of local N-gram-specific absorption rate-optimized radiofrequency pulses for parallel transmit systems

    NARCIS (Netherlands)

    Sbrizzi, Alessandro; Hoogduin, Hans; Lagendijk, Jan J.; Luijten, Peter; Sleijpen, Gerard L. G.; van den Berg, Cornelis A. T.

    2012-01-01

    Designing multidimensional radiofrequency pulses for clinical application must take into account the local specific absorption rate (SAR) as controlling the global SAR does not guarantee suppression of hot spots. The maximum peak SAR, averaged over an N grams cube (local NgSAR), must be kept under c

  8. Local-scale modelling of density-driven flow for the phases of repository operation and post-closure at Beberg

    Energy Technology Data Exchange (ETDEWEB)

    Jaquet, O.; Siegel, P. [Colenco Power Engineering Ltd, Baden-Daettwil (Switzerland)

    2004-09-01

    A hydrogeological model was developed for Beberg with the aim of evaluating the impact of a repository (for the operational and post-closure phases) while accounting for the effects of density-driven flow. Two embedded scales were taken into account for this modelling study: a local scale at which the granitic medium was considered as a continuum and a repository scale, where the medium is fractured and therefore was regarded to be discrete. The following step-wise approach was established to model density-driven flow at both repository and local scale: (a) modelling fracture networks at the repository scale, (b) upscaling the hydraulic properties to a continuum at local scale and (c) modelling density-driven flow to evaluate repository impact at local scale. The results demonstrate the strong impact of the repository on the flow field during the phase of operation. The distribution of the salt concentration is affected by a large upcoming effect with increased relative concentration and by the presence of fracture zones carrying freshwater from the surface. The concentrations obtained for the reference case, expressed in terms of percentage with respect to the maximum (prescribed) value in the model, are as follows: ca 30% for the phase of desaturation, and ca 20% for the resaturation phase. For the reference case, the impact of repository operations appears no longer visible after a resaturation period of about 20 years after repository closure; under resaturation conditions, evidence of the operational phase has already disappeared in terms of the observed hydraulic and concentration fields. Sensitivity calculations have proven the importance of explicitly discretising repository tunnels when assessing resaturation time and maximum concentration values. Furthermore, the definition of a fixed potential as boundary condition along the model's top surface is likely to provide underestimated values for the maximum concentration and overestimated flow rates in

  9. Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data

    Science.gov (United States)

    Lücke, O. H.; Arroyo, I. G.

    2015-10-01

    The eastern part of the oceanic Cocos Plate presents a heterogeneous crustal structure due to diverse origins and ages as well as plate-hot spot interactions which originated the Cocos Ridge, a structure that converges with the Caribbean Plate in southeastern Costa Rica. The complex structure of the oceanic plate directly influences the dynamics and geometry of the subduction zone along the Middle American Trench. In this paper an integrated interpretation of the slab geometry in Costa Rica is presented based on 3-D density modeling of combined satellite and surface gravity data, constrained by available geophysical and geological data and seismological information obtained from local networks. The results show the continuation of steep subduction geometry from the Nicaraguan margin into northwestern Costa Rica, followed by a moderate dipping slab under the Central Cordillera toward the end of the Central American Volcanic Arc. Contrary to commonly assumed, to the southeast end of the volcanic arc, our preferred model shows a steep, coherent slab that extends up to the landward projection of the Panama Fracture Zone. Overall, a gradual change in the depth of the intraplate seismicity is observed, reaching 220 km in the northwestern part, and becoming progressively shallower toward the southeast, where it reaches a maximum depth of 75 km. The changes in the terminal depth of the observed seismicity correlate with the increased density in the modeled slab. The absence of intermediate depth (> 75 km) intraplate seismicity in the southeastern section and the higher densities for the subducted slab in this area, support a model in which dehydration reactions in the subducted slab cease at a shallower depth, originating an anhydrous and thus aseismic slab.

  10. Big city, small world: density, contact rates, and transmission of dengue across Pakistan.

    Science.gov (United States)

    Kraemer, M U G; Perkins, T A; Cummings, D A T; Zakar, R; Hay, S I; Smith, D L; Reiner, R C

    2015-10-06

    Macroscopic descriptions of populations commonly assume that encounters between individuals are well mixed; i.e. each individual has an equal chance of coming into contact with any other individual. Relaxing this assumption can be challenging though, due to the difficulty of acquiring detailed knowledge about the non-random nature of encounters. Here, we fitted a mathematical model of dengue virus transmission to spatial time-series data from Pakistan and compared maximum-likelihood estimates of 'mixing parameters' when disaggregating data across an urban-rural gradient. We show that dynamics across this gradient are subject not only to differing transmission intensities but also to differing strengths of nonlinearity due to differences in mixing. Accounting for differences in mobility by incorporating two fine-scale, density-dependent covariate layers eliminates differences in mixing but results in a doubling of the estimated transmission potential of the large urban district of Lahore. We furthermore show that neglecting spatial variation in mixing can lead to substantial underestimates of the level of effort needed to control a pathogen with vaccines or other interventions. We complement this analysis with estimates of the relationships between dengue transmission intensity and other putative environmental drivers thereof.

  11. Accurate localized resolution of identity approach for linear-scaling hybrid density functionals and for many-body perturbation theory

    Science.gov (United States)

    Ihrig, Arvid Conrad; Wieferink, Jürgen; Zhang, Igor Ying; Ropo, Matti; Ren, Xinguo; Rinke, Patrick; Scheffler, Matthias; Blum, Volker

    2015-09-01

    A key component in calculations of exchange and correlation energies is the Coulomb operator, which requires the evaluation of two-electron integrals. For localized basis sets, these four-center integrals are most efficiently evaluated with the resolution of identity (RI) technique, which expands basis-function products in an auxiliary basis. In this work we show the practical applicability of a localized RI-variant (‘RI-LVL’), which expands products of basis functions only in the subset of those auxiliary basis functions which are located at the same atoms as the basis functions. We demonstrate the accuracy of RI-LVL for Hartree-Fock calculations, for the PBE0 hybrid density functional, as well as for RPA and MP2 perturbation theory. Molecular test sets used include the S22 set of weakly interacting molecules, the G3 test set, as well as the G2-1 and BH76 test sets, and heavy elements including titanium dioxide, copper and gold clusters. Our RI-LVL implementation paves the way for linear-scaling RI-based hybrid functional calculations for large systems and for all-electron many-body perturbation theory with significantly reduced computational and memory cost.

  12. Saturation deficit and deer density affect questing activity and local abundance of Ixodes ricinus (Acari, Ixodidae) in Italy.

    Science.gov (United States)

    Tagliapietra, V; Rosà, R; Arnoldi, D; Cagnacci, F; Capelli, G; Montarsi, F; Hauffe, H C; Rizzoli, A

    2011-12-29

    The wood tick Ixodes ricinus, one of the most common arthropod-borne disease vectors, is of increasing relevance for human and animal health in Europe. The aim of this study was to determine the relative contribution of several abiotic and biotic factors potentially affecting questing activity and local abundance of I. ricinus in Italy, considering the scale at which these factors interact with the host-seeking ticks. Within EDEN, a large-scale EU collaborative project on eco-epidemiology of vector-borne diseases, we collected questing ticks for three consecutive years using a standard protocol at eleven sites in the Italian Alps and Apennines. A total of 25 447 I. ricinus were collected. All sites showed the same annual pattern of tick activity (bimodal for nymphs and unimodal for larvae and adults), although the abundance of nymphs was statistically different between sites and years. A Generalized Linear Mixed Model and a Linear Mixed Model fitted to data for nymphs, showed that while the principal variables affecting the local abundance of questing ticks were saturation deficit (an index combining temperature and relative humidity) and red deer density, the most important variable affecting questing nymph activity was saturation deficit. As for the timing of seasonal emergence, we confirmed that the threshold temperature at this latitude for larvae is 10°C (mean maximum) while that for nymphs is 8°C.

  13. Prickle2 is localized in the postsynaptic density and interacts with PSD-95 and NMDA receptors in the brain.

    Science.gov (United States)

    Hida, Yamato; Fukaya, Masahiro; Hagiwara, Akari; Deguchi-Tawarada, Maki; Yoshioka, Toshinori; Kitajima, Isao; Inoue, Eiji; Watanabe, Masahiko; Ohtsuka, Toshihisa

    2011-06-01

    The planar cell polarity (PCP) protein, Prickle (Pk), is conserved in invertebrates and vertebrates, and regulates cellular morphogenesis and movement. Vertebrate Pk consists of at least two family members, Pk1 and Pk2, both of which are expressed in the brain; however, their localization and function at synapses remain elusive. Here, we show that Pk2 is expressed mainly in the adult brain and is tightly associated with the postsynaptic density (PSD) fraction obtained by subcellular fractionation. In primary cultured rat hippocampal neurons, Pk2 is colocalized with PSD-95 and synaptophysin at synapses. Moreover, immunoelectron microcopy shows that Pk2 is localized at the PSD of asymmetric synapses in the hippocampal CA1 region. Biochemical assays identified that Pk2 forms a complex with PSD proteins including PSD-95 and NMDA receptor subunits via the direct binding to the C-terminal guanylate kinase domain of PSD-95. These results indicate that Pk2 is a novel PSD protein that interacts with PSD-95 and NMDA receptors through complex formations in the brain.

  14. First-principles local density approximation (LDA)+ U and generalized gradient approximation (GGA) + U studies of plutonium oxides

    Institute of Scientific and Technical Information of China (English)

    Sun Bo; Zhang Ping

    2008-01-01

    The electronic structures and properties of PuO2 and Pu2O3 have been studied according to the first principles by using the all-electron projector-augmented-wave (PAW) method. The local density approximation (LDA)+U and the generalized gradient approximation (GGA)+U formalisms have been used to account for the strong on-site Coulomb repulsion among the localized Pu 5f electrons. We discuss how the properties of PuO2 and Pu2O3 are affected by choosing the values of U and exchange-correlation potential. Also, the oxidation reaction of Pu2O3, leading to the formation of PuO2, and its dependence on U and exchange-correlation potential have been studied. Our results show that by choosing an appropriate U it is possible to consistently describe structural, electronic, and thermodynamic properties of PuO2 and Pu2O3, which enable the modelling of the redox process involving Pu-based materials.

  15. Coherence of heart rate variability and local physical fields in monitoring studies

    Science.gov (United States)

    Tuzhilkin, D. A.; Borodin, A. S.

    2015-11-01

    Technological advances have led to a substantial modification of the physical fields of the environment, which could affect the status of living organisms under their constant exposure. In this study, the activity of human cardiovascular system under the influence of a complex natural physical environmental factors investigated. The study was conducted on a representative homogeneous sample (44 persons aged 19 to 22 years) by simultaneous monitoring of electrocardiograms and natural physical fields in Tomsk (geomagnetic field, meteorological parameters - temperature, pressure and humidity, surface wind speed, the parameters of the Schumann resonance - amplitude, frequency and quality factor of the first four modes in the range of 6 to 32 Hz, the power spectral density infrasonic background in the range of from 0,5 to 32 Hz). It was shown that among the set of parameters of physical fields present field that can resonate in the functioning of the human organism. The greatest coherence with heart rate variability detect variations eastern component of the geomagnetic field.

  16. Increased survival rate by local release of diclofenac in a murine model of recurrent oral carcinoma

    Directory of Open Access Journals (Sweden)

    Will OM

    2016-10-01

    Full Text Available Olga Maria Will,1,* Nicolai Purcz,2,* Athena Chalaris,3 Carola Heneweer,4,5 Susann Boretius,1 Larissa Purcz,2 Lila Nikkola,6 Nureddin Ashammakhi,6 Holger Kalthoff,7 Claus-Christian Glüer,1 Jörg Wiltfang,2 Yahya Açil,2 Sanjay Tiwari1 1Section Biomedical Imaging, Clinic for Radiology and Neuroradiology, MOIN CC, 2Department of Oral and Maxillofacial Surgery, University Hospital Schleswig-Holstein, 3Institute of Biochemistry, Christian-Albrechts-Universität zu Kiel, 4Clinic for Radiology and Neuroradiology, University Hospital Schleswig-Holstein, Kiel, 5Institute for Diagnostic and Interventional Radiology, University Hospital Cologne, Cologne, Germany; 6Department of Biomedical Engineering, Tampere University of Technology, Tampere, Finland; 7Institute for Experimental Cancer Research, University Hospital Schleswig-Holstein, Kiel, Germany *These authors contributed equally to this work Abstract: Despite aggressive treatment with radiation and combination chemotherapy following tumor resection, the 5-year survival rate for patients with head and neck cancer is at best only 50%. In this study, we examined the therapeutic potential of localized release of diclofenac from electrospun nanofibers generated from poly(d,l-lactide-co-glycolide polymer. Diclofenac was chosen since anti-inflammatory agents that inhibit cyclooxygenase have shown great potential in their ability to directly inhibit tumor growth as well as suppress inflammation-mediated tumor growth. A mouse resection model of oral carcinoma was developed by establishing tumor growth in the oral cavity by ultrasound-guided injection of 1 million SCC-9 cells in the floor of the mouth. Following resection, mice were allocated into four groups with the following treatment: 1 no treatment, 2 implanted scaffolds without diclofenac, 3 implanted scaffolds loaded with diclofenac, and 4 diclofenac given orally. Small animal ultrasound and magnetic resonance imaging were utilized for longitudinal

  17. Neighborhood alcohol outlet density and rates of child abuse and neglect: moderating effects of access to substance abuse services.

    Science.gov (United States)

    Morton, Cory M; Simmel, Cassandra; Peterson, N Andrew

    2014-05-01

    This study investigates the relationship between concentrations of on- and off-premises alcohol outlets and rates of child abuse and neglect. Additionally, the study seeks to locate protective features of a neighborhood's built environment by investigating the potentially moderating role that access to substance abuse treatment and prevention services plays in the relationship between alcohol outlet density and child maltreatment. Using a cross-sectional design, this ecological study utilized data from 163 census tracts in Bergen County, New Jersey, on reports of child abuse and neglect, alcohol outlets, substance abuse treatment and prevention facilities, and the United States Census to investigate the linkages between socioeconomic structure, alcohol availability, and access to substance abuse service facilities on rates of child abuse and neglect. Findings indicate areas with a greater concentration of on-premises alcohol outlets (i.e., bars) had higher rates of child neglect, and those with easier access to substance abuse services had lower rates of neglect, controlling for neighborhood demographic and socioeconomic structure. Additionally, the relationship between on-premises alcohol outlet density and rates of child neglect was moderated by the presence of substance abuse service facilities. A greater concentration of off-premises outlets (i.e., liquor stores) was associated with lower rates of physical abuse. Findings suggest that the built environment and socioeconomic structure of neighborhoods have important consequences for child well-being. The implications for future research on the structural features of neighborhoods that are associated with child well-being are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Density and temperature dependent feeding rates in an established and an alien freshwater gammarid fed on chironomid larvae

    Directory of Open Access Journals (Sweden)

    Dieter WALOSZEK

    2011-02-01

    Full Text Available We compared feeding rates of the well-established, non-invasive amphipod Gammarus roeselii with those of the invasive Dikerogammarus villosus at different prey densities and different temperatures in laboratory experiments using chironomid larvae as prey. Feeding rates were very variable in both species but higher in the invader species than in the well-established non-invasive species. These results were age independent. At high temperature (18-20 °C and high prey density (≥1000 prey m-2 one large adult D. villosus consumed 6-9 prey day-1 on average while one G. roeselii consumed 4-7 prey d-1 and one smaller D. villosus of a length of 8-10 mm consumed 2-5 prey d-1 while one G. roeselii of the same length consumed 3 prey d-1. Predation rate decreased considerably from high (18-20 °C to low temperature (3±2 °C, from 9 to 4 prey predator-1 d-1 in D. villosus and from 7.5 to 2.5 prey predator-1 d-1 in G. roeselii. We conclude that both gammarids consumed a biomass in the range of 1/2 to 1/3 to their own biomass and that low predation/feeding rate at low temperature could be a reason why, in some places, indigenous gammarids can re-colonize their former habitats for a short period of time in cold winter and early spring in spite of the presence of the invasive. We further conclude that differences in weight between the species in particular in the experiments with adults can have influenced feeding rates; possibly differences in weight- specific feeding rates are small.

  19. The relationship between local liquid density and force applied on a tip of atomic force microscope: A theoretical analysis for simple liquids

    Energy Technology Data Exchange (ETDEWEB)

    Amano, Ken-ichi, E-mail: aman@tohoku-pharm.ac.jp; Takahashi, Ohgi [Faculty of Pharmaceutical Sciences, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558 (Japan); Suzuki, Kazuhiro [Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510 (Japan); Fukuma, Takeshi [Bio-AFM Frontier Research Center, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Onishi, Hiroshi [Department of Chemistry, Faculty of Science, Kobe University, Nada-ku, Kobe 657-8501 (Japan)

    2013-12-14

    The density of a liquid is not uniform when placed on a solid. The structured liquid pushes or pulls a probe employed in atomic force microscopy, as demonstrated in a number of experimental studies. In the present study, the relation between the force on a probe and the local density of a liquid is derived based on the statistical mechanics of simple liquids. When the probe is identical to a solvent molecule, the strength of the force is shown to be proportional to the vertical gradient of ln(ρ{sub DS}) with the local liquid's density on a solid surface being ρ{sub DS}. The intrinsic liquid's density on a solid is numerically calculated and compared with the density reconstructed from the force on a probe that is identical or not identical to the solvent molecule.

  20. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory.

    Science.gov (United States)

    Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J; Lopata, Kenneth

    2016-09-07

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

  1. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory

    Science.gov (United States)

    Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J.; Lopata, Kenneth

    2016-09-01

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

  2. Variation in radical decay rates in epoxy as a function of crosslink density

    Science.gov (United States)

    Kent, G. M.; Memory, J. M.; Gilbert, R. D.; Fornes, R. E.

    1983-01-01

    A study was made of the behavior of radicals generated by Co-60 gamma radiation in the epoxy system tetraglycidyl-4,4'-diaminodiphenyl methane (TGDDM) cured with 4,4'-diaminodiphenyl sulfone (DDS). The molar ratio of TGDDM to DDS was varied in the epoxy samples, and they were prepared under the same curing conditions to obtain various extents of crosslinking. ESR spectrometry data suggest that the rate of decay of radicals is related to inhomogeneities in the resin, with radicals in the highly crosslinked regions having long decay times. The inhomogeneities are thought to be due to statistical variation associated with the complex crosslinking reactions or to difficulties in mixing the reactants.

  3. The density structure and star formation rate of non-isothermal polytropic turbulence

    CERN Document Server

    Federrath, Christoph

    2014-01-01

    The interstellar medium of galaxies is governed by supersonic turbulence, which likely controls the star formation rate (SFR) and initial mass function (IMF) of stars. Turbulence also plays an important role during structure formation in the early Universe. Despite its ubiquity and importance, we have yet to understand the statistics of turbulence. ISM turbulence is non-universal, with a wide range of Mach numbers, magnetic fields strengths, and is driven by various stellar feedback and galactic processes. Although some of these parameters were explored, the bulk of previous work assumed that the gas is isothermal. However, cold molecular clouds form out of the warm atomic medium, with the gas passing through various chemical and thermodynamic phases that are not isothermal. Here we determine the role of temperature variations by modelling non-isothermal hydrodynamic turbulence with a polytropic equation of state (EOS), P~rho^Gamma. We use grid resolutions of 2048^3 cells and compare polytropic exponents Gamm...

  4. ON THE INCONSISTENCY BETWEEN COSMIC STELLAR MASS DENSITY AND STAR FORMATION RATE UP TO z ∼ 8

    Energy Technology Data Exchange (ETDEWEB)

    Yu, H.; Wang, F. Y., E-mail: fayinwang@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2016-04-01

    In this paper, we test the discrepancy between the stellar mass density (SMD) and instantaneous star formation rate in the redshift range 0 < z < 8 using a large observational data sample. We first compile the measurements of SMDs up to z ∼ 8. Comparing the observed SMDs with the time-integral of instantaneous star formation history (SFH), we find that the observed SMDs are lower than that implied from the SFH at z < 4. We also use the Markov chain Monte Carlo (MCMC) method to derive the best-fitting SFH from the observed SMD data. At 0.5 < z < 6, the observed star formation rate densities are larger than the best-fitting one, especially at z ∼ 2 where they are larger by a factor of about two. However, at lower (z < 0.5) and higher redshifts (z > 6), the derived SFH is consistent with the observations. This is the first time that the discrepancy between the observed SMD and instantaneous star formation rate has been tested up to very high redshift z ≈ 8 using the MCMC method and a varying recycling factor. Several possible reasons for this discrepancy are discussed, such as underestimation of SMD, initial mass function, and evolution of cosmic metallicity.

  5. Upconversion in a Bragg structure: photonic effects of a modified local density of states and irradiance on luminescence and upconversion quantum yield.

    Science.gov (United States)

    Hofmann, Clarissa L M; Herter, Barbara; Fischer, Stefan; Gutmann, Johannes; Goldschmidt, Jan Christoph

    2016-06-27

    In this paper, we present a comprehensive simulation-based analysis of the two photonic effects of a Bragg stack - a modified local density of photon states (LDOS) and an enhanced local irradiance - on the upconversion (UC) luminescence and quantum yield of the upconverter β-NaYF4 doped with 25% Er3+. The investigated Bragg stack consists of alternating layers of TiO2 and Poly(methylmethacrylate), the latter containing upconverter nanoparticles. Using experimentally determined input parameters, the photonic effects are first simulated separately and subsequently coupled in a rate equation model, describing the dynamics of the UC processes within β-NaYF4:25% Er3+. With this integrated simulation model, the Bragg stack design is optimized to maximize either the UC quantum yield (UCQY) or UC luminescence. We find that in an optimized Bragg stack, due to the modified LDOS, the maximum UCQY is enhanced from 14% to 16%, compared to an unstructured layer of upconverter material. Additionally, this maximum UCQY can already be reached at an incident irradiance as low as 100 W/m2. With a Bragg stack design that maximizes UC luminescence, enhancement factors of up to 480 of the UC luminescence can be reached.

  6. A two-photon laser induced fluorescence diagnostic with improved sensitivity, localization, and measurement rate

    Science.gov (United States)

    Elliott, Drew; Scime, Earl; Short, Zachary

    2016-10-01

    A two-photon absorption laser induced fluorescence diagnostic has been developed for measuring neutrals in fusion plasmas. Implementation of this diagnostic on the HIT-SI3 spheromak has demonstrated the sensitivity of the diagnostic and shown that measurements taken over several plasma pulses are possible. These measurements yielded an unexpected loss of signal when complex collection optics were utilized. Simulations show that this loss of signal can be explained by chromatic aberrations caused by the disparate Kr and D emission. This loss of signal has been addressed with the development of a new calibration scheme involving xenon gas. The Xe calibration scheme emission occurs at 656.00 nm while the deuterium emission is 656.09 nm. This nearly identical emission allows for advanced optical techniques such as confocal collection/injection and spatial filtering to be employed without loss of signal. Spatial filtering has been demonstrated to decrease noise while improving measurement localization, while confocal collection/injection allows for probing and measuring to occur through one viewport. The Xe scheme also allows for a Doppler-free hydrogen measurement. Doppler-free measurements eliminate the need to scan the laser spectrally thus greatly increasing the rate of measurement.

  7. The Rate-Controlled Constrained-Equilibrium Approach to Far-From-Local-Equilibrium Thermodynamics

    Directory of Open Access Journals (Sweden)

    Hameed Metghalchi

    2012-01-01

    Full Text Available The Rate-Controlled Constrained-Equilibrium (RCCE method for the description of the time-dependent behavior of dynamical systems in non-equilibrium states is a general, effective, physically based method for model order reduction that was originally developed in the framework of thermodynamics and chemical kinetics. A generalized mathematical formulation is presented here that allows including nonlinear constraints in non-local equilibrium systems characterized by the existence of a non-increasing Lyapunov functional under the system’s internal dynamics. The generalized formulation of RCCE enables to clarify the essentials of the method and the built-in general feature of thermodynamic consistency in the chemical kinetics context. In this paper, we work out the details of the method in a generalized mathematical-physics framework, but for definiteness we detail its well-known implementation in the traditional chemical kinetics framework. We detail proofs and spell out explicit functional dependences so as to bring out and clarify each underlying assumption of the method. In the standard context of chemical kinetics of ideal gas mixtures, we discuss the relations between the validity of the detailed balance condition off-equilibrium and the thermodynamic consistency of the method. We also discuss two examples of RCCE gas-phase combustion calculations to emphasize the constraint-dependent performance of the RCCE method.

  8. Gas surface density, star formation rate surface density, and the maximum mass of young star clusters in a disk galaxy. II. The grand-design galaxy M51

    CERN Document Server

    Gonzalez-Lopezlira, Rosa A; Kroupa, Pavel

    2013-01-01

    We analyze the relationship between maximum cluster mass, and surface densities of total gas (Sigma_gas), molecular gas (Sigma_H_2), neutral gas (Sigma_HI) and star formation rate (Sigma_SFR) in the grand design galaxy M51, using published gas data and a catalog of masses, ages, and reddenings of more than 1800 star clusters in its disk, of which 223 are above the cluster mass distribution function completeness limit. We find for clusters older than 25 Myr that M_3rd, the median of the 5 most massive clusters, is proportional to Sigma_HI^0.4. There is no correlation with Sigma_gas, Sigma_H2, or Sigma_SFR. For clusters younger than 10 Myr, M_3rd is proportional to Sigma_HI^0.6, M_3rd is proportional to Sigma_gas^0.5; there is no correlation with either Sigma_H_2 or Sigma_SFR. The results could hardly be more different than those found for clusters younger than 25 Myr in M33. For the flocculent galaxy M33, there is no correlation between maximum cluster mass and neutral gas, but M_3rd is proportional to Sigma_g...

  9. Studies on the Construction Parameter of an Artificial Occluded Cell for In-situ Inspection of the Propagation Rate of Localized Corrosion

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An artificial localized corrosion system is assembled and some parameters related to the localized corrosion in active dissolution state(i.e.,non-passive state)have been studied.The results showed that the developed electrochemical system can satisfactorily imitate a naturally formed localized corrosion and the coupling current can indicate the maximum localized propagating rate.In this artificial system, the anodic dissolution reaction followed the auto-catalytic mechanism.The localized corrosion current density was dependent on the area ratio R of the cathode tothe occluded anode. While R was equal to or more than 6, the coupling current reached at a maximum value and did not alter with the increase in R-value. Therefore, R=7 is chosen as one of these optimum parameters used in constructing the system, with which the biggest galvanic current might be obtained. In contrast, the thickness of the polymer filler separating the occluded anode area from the bulk electrolyte solution and the volume of the occluded anode area did not affect the corrosion current obviously. They might affect the response time to approach a steady state.

  10. local

    Directory of Open Access Journals (Sweden)

    Abílio Amiguinho

    2005-01-01

    Full Text Available The process of socio-educational territorialisation in rural contexts is the topic of this text. The theme corresponds to a challenge to address it having as main axis of discussion either the problem of social exclusion or that of local development. The reasons to locate the discussion in this last field of analysis are discussed in the first part of the text. Theoretical and political reasons are there articulated because the question is about projects whose intentions and practices call for the political both in the theoretical debate and in the choices that anticipate intervention. From research conducted for several years, I use contributions that aim at discuss and enlighten how school can be a potential locus of local development. Its identification and recognition as local institution (either because of those that work and live in it or because of those that act in the surrounding context are crucial steps to progressively constitute school as a partner for development. The promotion of the local values and roots, the reconstruction of socio-personal and local identities, the production of sociabilities and the equation and solution of shared problems were the dimensions of a socio-educative intervention, markedly globalising. This scenario, as it is argued, was also, intentionally, one of transformation and of deliberate change of school and of the administration of the educative territoires.

  11. The evolution of the star formation rate function and cosmic star formation rate density of galaxies at z ˜ 1-4

    Science.gov (United States)

    Katsianis, A.; Tescari, E.; Blanc, G.; Sargent, M.

    2017-02-01

    We investigate the evolution of the galaxy star formation rate function (SFRF) and cosmic star formation rate density (CSFRD) of z ˜ 1-4 galaxies, using cosmological smoothed particle hydrodynamic (SPH) simulations and a compilation of ultraviolet (UV), infrared (IR) and Hα observations. These tracers represent different populations of galaxies with the IR light being a probe of objects with high star formation rates and dust contents, while UV and Hα observations provide a census of low star formation galaxies where mild obscuration occurs. We compare the above SFRFs with the results of SPH simulations run with the code P-GADGET3(XXL). We focus on the role of feedback from active galactic nuclei (AGN) and supernovae in form of galactic winds. The AGN feedback prescription that we use decreases the simulated CSFRD at z < 3 but is not sufficient to reproduce the observed evolution at higher redshifts. We explore different wind models and find that the key factor for reproducing the evolution of the observed SFRF and CSFRD at z ˜ 1-4 is the presence of a feedback prescription that is prominent at high redshifts (z ≥ 4) and becomes less efficient with time. We show that variable galactic winds which are efficient at decreasing the SFRs of low-mass objects are quite successful in reproducing the observables.

  12. The evolution of the star formation rate function and cosmic star formation rate density of galaxies at $z \\sim 1-4$

    CERN Document Server

    Katsianis, Antonios; Blanc, Guillermo; Sargent, Mark

    2016-01-01

    We investigate the evolution of the galaxy Star Formation Rate Function (SFRF) and Cosmic Star Formation Rate Density (CSFRD) of $z\\sim 1-4 $ galaxies, using cosmological Smoothed Particle Hydrodynamic (SPH) simulations and a compilation of UV, IR and H$\\alpha$ observations. These tracers represent different populations of galaxies with the IR light being a probe of objects with high star formation rates and dust contents, while UV and H$\\alpha$ observations provide a census of low star formation galaxies where mild obscuration occurs. We compare the above SFRFs with the results of SPH simulations run with the code {\\small{P-GADGET3(XXL)}}. We focus on the role of feedback from Active Galactic Nuclei (AGN) and supernovae in form of galactic winds. The AGN feedback prescription that we use decreases the simulated CSFRD at $z < 3$ but is not sufficient to reproduce the observed evolution at higher redshifts. We explore different wind models and find that the key factor for reproducing the evolution of the ob...

  13. Importance of mycorrhization helper bacteria cell density and metabolite localization for the Pinus sylvestris-Lactarius rufus symbiosis.

    Science.gov (United States)

    Aspray, Thomas J; Eirian Jones, E; Whipps, John M; Bending, Gary D

    2006-04-01

    Mycorrhization helper bacteria, Paenibacillus sp. EJP73 and Burkholderia sp. EJP67, were used to study the importance of bacterial inoculum dose and bacterial derived soluble and volatile metabolites localization for enhancing mycorrhiza formation in the Pinus sylvestris-Lactarius rufus symbiosis, using a laboratory based microcosm. EJP73 and EJP67 produced different responses in relation to the inoculum dose; EJP73 significantly enhanced mycorrhiza formation to the same degree at all doses tested (10(5), 10(7), 10(9) and 10(10) CFU mL(-1)), whereas, EJP67 only stimulated mycorrhiza formation within a narrow range of inoculum densities (10(7) and 10(9) CFU mL(-1)). The importance of soluble bacterial metabolites was assessed by applying spent broth derived from exponential and stationary phase bacterial cultures to microcosms. No spent broth enhanced mycorrhiza formation over the control. As EJP73 produced the helper effect over a wide range of inoculum doses, this bacterium was chosen for further study. Physical separation of EJP73 from the fungal and plant symbiosis partners was carried out, in order to determine the contribution of constitutively produced bacterial volatile metabolites to the mycorrhization helper bacteria effect. When EJP73 was physically separated from the symbiosis, it had a significant negative effect on mycorrhiza formation. These results suggest that close proximity, or indeed cell contact, is required for the helper effect. Therefore, fluorescent in situ hybridization in conjunction with cryosectioning was used to determine the localization of EJP73 in mycorrhizal tissue. The cells were found to occur as rows or clusters ( approximately 10 cells) within the mycorrhizal mantle, both at the root tip and along the length of the mycorrhizal short roots.

  14. Modeling high-pressure adsorption of gas mixtures on activated carbon and coal using a simplified local-density model.

    Science.gov (United States)

    Fitzgerald, James E; Robinson, Robert L; Gasem, Khaled A M

    2006-11-07

    The simplified local-density (SLD) theory was investigated regarding its ability to provide accurate representations and predictions of high-pressure supercritical adsorption isotherms encountered in coalbed methane (CBM) recovery and CO2 sequestration. Attention was focused on the ability of the SLD theory to predict mixed-gas adsorption solely on the basis of information from pure gas isotherms using a modified Peng-Robinson (PR) equation of state (EOS). An extensive set of high-pressure adsorption measurements was used in this evaluation. These measurements included pure and binary mixture adsorption measurements for several gas compositions up to 14 MPa for Calgon F-400 activated carbon and three water-moistened coals. Also included were ternary measurements for the activated carbon and one coal. For the adsorption of methane, nitrogen, and CO2 on dry activated carbon, the SLD-PR can predict the component mixture adsorption within about 2.2 times the experimental uncertainty on average solely on the basis of pure-component adsorption isotherms. For the adsorption of methane, nitrogen, and CO2 on two of the three wet coals, the SLD-PR model can predict the component adsorption within the experimental uncertainties on average for all feed fractions (nominally molar compositions of 20/80, 40/60, 60/40, and 80/20) of the three binary gas mixture combinations, although predictions for some specific feed fractions are outside of their experimental uncertainties.

  15. The butterflies of Barro Colorado Island: Local extinction rates since the 1930's

    Science.gov (United States)

    Few data are available about the regional or local extinction of tropical butterfly species. When confirmed, local extinction was often due to the loss of host-plant species. We used published lists and recent monitoring programs to evaluate changes in butterfly composition on Barro Colorado Island ...

  16. Local Spin Density Approximation Solution for Spinel LiV2O4: Spin Fluctuation as a Possible Role for Heavy Fermion

    Institute of Scientific and Technical Information of China (English)

    谭明秋; 陶向明

    2001-01-01

    We report on a self-consistent full-potential linear muffin tin orbital band-structure calculation for the heavy fermion (HF) compound LiV2O4. It is found that a stable local spin density approximation solution for LiV2O4 is lower in total energy than the local density approximation calculation. We speculate that the mechanism responsible for HF properties in LiV2O4 might be of spin fluctuation type and is different from the Kondo mechanism in conventional 4f and 5f HF compounds.

  17. Global and local critical current density in superconducting SmFeAsO{sub 1-x}F{sub x} measured by two methods

    Energy Technology Data Exchange (ETDEWEB)

    Otabe, E.S., E-mail: otabe@cse.kyutech.ac.j [Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502 (Japan); Kiuchi, M.; Kawai, S. [Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502 (Japan); Morita, Y.; Ge, J.; Ni, B. [Department of Life, Environment and Material Science, Fukuoka Institute of Technology, 3-30-1 Wajirohigashi, Higashi-ku, Fukuoka 811-0295 (Japan); Gao, Z.; Wang, L.; Qi, Y.; Zhang, X.; Ma, Y. [Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100190 (China)

    2009-11-01

    The critical current densities of polycrystalline bulk SmFeAsO{sub 1-x}F{sub x} prepared by the powder-in-tube (PIT) method and by a conventional solid-state reaction were investigated using the remnant magnetic moment method and Campbell's method. Two types of shielding current, corresponding to global and local critical current densities J{sub c} were observed using both measurement methods. The global and local J{sub c} were on the order of 10{sup 7} A/m{sup 2} and 10{sup 10} A/m{sup 2} at 5 K, respectively. The local J{sub c} decreased slightly with increasing magnetic field. The global J{sub c} was independent of the preparation method, while the local J{sub c} was larger for samples prepared by PIT than for those prepared by solid-state reaction.

  18. Local-field corrections to the decay rate of excited molecules in absorbing cavities the Onsager model

    CERN Document Server

    Tomas, M S

    2000-01-01

    The decay rate and the classical radiation power of an excited molecule (atom) located in the center of a dispersive and absorbing dielectric sphere taken as a simple model of a cavity are calculated adopting the Onsager model for the local field. The local-field correction factor to the external (radiation and absorption) power loss of the molecule is found to be $|3\\epsilon(\\omega)/[3\\epsilon(\\omega)+1]|^2$, with $\\epsilon(\\omega)$ being the dielectric function of the sphere. However, local-field corrections to the total decay rate (power loss) of the molecule are found to be much more complex, including those to the decay rate in the infinite cavity medium, as derived very recently by Scheel et al. [Rev. A 60, 4094 (1999)], and similiar corrections to the cavity-induced decay rate. The results obtained can be cast into model-independent forms. This suggests the general results for the local-field corrections to the decay rate and to the external power loss of a molecule in an absorbing cavity valid for mol...

  19. Correlation between Change Rates of GRACE-derived Density and Ground-measured Temperature in Tibetan Plateau, 2004-2008

    Science.gov (United States)

    Zhang, K.; Ma, J.

    2011-12-01

    The amount of mountain glaciers on the Tibetan plateau accounts for 81.6% of the total glacial volume in China, and thus they become origination of Asia's seven major rivers including the Yangtze River, Yellow River, Ganges River, Indus River, Yarlung Zangbo River, and Nujiang River. Unfortunately, with the climate warming since the 20th century, most glaciers are retreating at a rate of 7.0 percent annually. The fast rate of glacier melt has meant more water runoff from the plateau which might exacerbate soil erosion, trigger drought and lead to sandstorms and desertification in the downstream regions. Thus, quantitive estimation and understanding of these glaciers' mass balance will be helpful to long-term sustainability of agriculture and hazard mitigation and give insights into climate change. As the primary factor for the glacier ice melting, the rising temperature should be correlated with the losing ice mass in the Tibetan plateau. However, quantification of glacier mass losses has been challenged, limited by temporarily and spatially sparse measurements using conventional data types and also due to the significant variations in glaciers' melting rates from region to region, and among glaciers in the same region. Nevertheless, the particular sensitivity of mountain glaciers to climate change makes it possible to estimate their mass change rates using GRACE even though the limited resolution. GRACE observations in southeastern Alaska, Patagonia and Tibet provided independent supports for the ability of glaciers' ice loss rates there (e.g., Matsuo and Heki, 2010). Here we expected to examine the correlation between Temperature Change Rates (TCRs) and Mass Change Rates (MCRs) and thus we computed the monthly density change and obtained the yearly Density Change Rates (DCRs) in Tibetan plateau of latitudes from 27N to 38N and longitudes ranging from 75E to 103E, and compared TCRs of ground-measured temperatures at 52 stations higher than 3000m with GRACE

  20. Stretch rate effects and flame surface densities in premixed turbulent combustion up to 1.25 MPa

    KAUST Repository

    Bagdanavicius, Audrius

    2015-11-01

    Independent research at two centres using a burner and an explosion bomb has revealed important aspects of turbulent premixed flame structure. Measurements at pressures and temperatures up to 1.25MPa and 673K in the two rigs were aimed at quantifying the influences of flame stretch rate and strain rate Markstein number, Masr , on both turbulent burning velocity and flame surface density. That on burning velocity is expressed through the stretch rate factor, Io , or probability of burning, Pb 0.5. These depend on Masr , but they grow in importance as the Karlovitz stretch factor, K, increases, and are evaluated from the associated burning velocity data. Planar laser tomography was employed to identify contours of reaction progress variable in both rigs. These enabled both an appropriate flame front for the measurement of the turbulent burning velocity to be identified, and flame surface densities, with the associated factors, to be evaluated. In the explosion measurements, these parameters were derived also from the flame surface area, the derived Pb 0.5 factor and the measured turbulent burning velocities. In the burner measurement they were calculated directly from the flame surface density, which was derived from the flame contours.A new overall correlation is derived for the Pb 0.5 factor, in terms of Masr at different K and this is discussed in the light of previous theoretical studies. The wrinkled flame surface area normalised by the area associated with the turbulent burning velocity measurement, and the ratio of turbulent to laminar burning velocity, ut /ul , are also evaluated. The higher the value of Pb0.5, the more effective is an increased flame wrinkling in increasing ut /ul A correlation of the product of k and the laminar flame thickness with Karlovitz stretch factor and Markstein number is explored using the present data and those

  1. Effect of cooling rate on the properties of high density polyethylene/multi-walled carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Dong; Harkin-Jones, Eileen [School of Mechanical and Aerospace Engineering, Queen’s University Belfast, BT9 5AH (United Kingdom); Linton, David [School of Electronics, Electrical Engineering and Computer Science, Queen’s University Belfast, BT9 5AH (United Kingdom)

    2015-05-22

    High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by melt mixing using twin-screw extrusion. The extruded pellets were compression moulded at 200°C for 5min followed by cooling at different cooling rates (20°C/min and 300°C/min respectively) to produce sheets for characterization. Scanning electron microscopy (SEM) shows that the MWCNTs are uniformly dispersed in the HDPE. At 4 wt% addition of MWCNTs composite modulus increased by over 110% compared with the unfilled HDPE (regardless of the cooling rate). The yield strength of both unfilled and filled HDPE decreased after rapid cooling by about 10% due to a lower crystallinity and imperfect crystallites. The electrical percolation threshold of composites, irrespective of the cooling rate, is between a MWCNT concentration of 1∼2 wt%. Interestingly, the electrical resistivity of the rapidly cooled composite with 2 wt% MWCNTs is lower than that of the slowly cooled composites with the same MWCNT loading. This may be due to the lower crystallinity and smaller crystallites facilitating the formation of conductive pathways. This result may have significant implications for both process control and the tailoring of electrical conductivity in the manufacture of conductive HDPE/MWCNT nanocomposites.

  2. Tensile fracture and shear localization under high loading rate in tungsten alloys

    OpenAIRE

    Couque, H.; Lankford, J.; Bose, A

    1992-01-01

    The influence of loading rate and microstructure on the tensile and compressive failure properties of three microstructurally dissimilar tungsten alloys has been investigated. Dynamic tensile fracture properties were characterized through fracture toughness tests performed at a stress intensity loading rate of 106 MPa $\\sqrt{{\\rm m}}$ s-1, and by tensile testing at a strain rate of 103 s-1. Shear banding phenomena were investigated by means of compression tests performed at strain rates of 5 ...

  3. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Science.gov (United States)

    Provine, J.; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin; Kim, Ki-Hyun; Prinz, Fritz B.

    2016-06-01

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiNx), particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiNx and evaluate the film's WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  4. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Provine, J., E-mail: jprovine@stanford.edu; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Kim, Ki-Hyun [Manufacturing Technology Center, Samsung Electronics, Suwon, Gyeonggi-Do (Korea, Republic of); Prinz, Fritz B. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2016-06-15

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiN{sub x}), particularly for use a low k dielectric spacer. One of the key material properties needed for SiN{sub x} films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiN{sub x} and evaluate the film’s WER in 100:1 dilutions of HF in H{sub 2}O. The remote plasma capability available in PEALD, enabled controlling the density of the SiN{sub x} film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiN{sub x} of 6.1 Å/min, which is similar to WER of SiN{sub x} from LPCVD reactions at 850 °C.

  5. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Directory of Open Access Journals (Sweden)

    J. Provine

    2016-06-01

    Full Text Available The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD of silicon nitride (SiNx, particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER in hydrofluoric (HF acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD of SiNx and evaluate the film’s WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  6. Area density of localization-entropy II: double cone-localization and quantum origin of the Bondi-Metzner-Sachs symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Schroer, Bert

    2006-04-15

    The holographic encoding is generalized to subalgebras of QFT localized in double cones. It is shown that as a result of this radically different spacetime encoding the modular group acts geometrically on the holographic image. As a result we obtain a formula for localization entropy which is identical to the previously derived formula for the wedge-localized subalgebra. The symmetry group in the holographic encoding turns out to be the Bondi-Metzner-Sachs group. (author)

  7. Constitutive expression of a COOH-terminal leucine mutant of lysosome-associated membrane protein-1 causes its exclusive localization in low density intracellular vesicles.

    Science.gov (United States)

    Akasaki, Kenji; Shiotsu, Keiko; Michihara, Akihiro; Ide, Norie; Wada, Ikuo

    2014-07-01

    Lysosome-associated membrane protein-1 (LAMP-1) is a type I transmembrane protein with a short cytoplasmic tail that possesses a lysosome-targeting signal of GYQTI(382)-COOH. Wild-type (WT)-LAMP-1 was exclusively localized in high density lysosomes, and efficiency of LAMP-1's transport to lysosomes depends on its COOH-terminal amino acid residue. Among many different COOH-terminal amino acid substitution mutants of LAMP-1, a leucine-substituted mutant (I382L) displays the most efficient targeting to late endosomes and lysosomes [Akasaki et al. (2010) J. Biochem. 148: , 669-679]. In this study, we generated two human hepatoma cell lines (HepG2 cell lines) that stably express WT-LAMP-1 and I382L, and compared their intracellular distributions. The subcellular fractionation study using Percoll density gradient centrifugation revealed that WT-LAMP-1 had preferential localization in the high density secondary lysosomes where endogenous human LAMP-1 was enriched. In contrast, a major portion of I382L was located in a low density fraction. The low density fraction also contained approximately 80% of endogenous human LAMP-1 and significant amounts of endogenous β-glucuronidase and LAMP-2, which probably represents occurrence of low density lysosomes in the I382L-expressing cells. Double immunofluorescence microscopic analyses distinguished I382L-containing intracellular vesicles from endogenous LAMP-1-containing lysosomes and early endosomes. Altogether, constitutive expression of I382L causes its aberrant intracellular localization and generation of low density lysosomes, indicating that the COOH-terminal isoleucine is critical for normal localization of LAMP-1 in the dense lysosomes.

  8. High Repetition-Rate Wakefield Electron Source Generated by Few-millijoule, 30 femtosecond Laser Pulses on a Density Downramp

    CERN Document Server

    He, Z -H; Easter, J H; Krushelnick, K; Nees, J A; Thomas, A G R

    2012-01-01

    We report on an experimental demonstration of laser wakefield electron acceleration using a sub-TW power laser by tightly focusing 30-fs laser pulses with only 8 mJ pulse energy on a 100 \\mu m scale gas target. The experiments are carried out at an unprecedented 0.5 kHz repetition rate, allowing "real time" optimization of accelerator parameters. Well-collimated and stable electron beams with a quasi-monoenergetic peak in excess of 100 keV are measured. Particle-in-cell simulations show excellent agreement with the experimental results and suggest an acceleration mechanism based on electron trapping on the density downramp, due to the time varying phase velocity of the plasma waves.

  9. Local, regional, and systemic recurrence rates in patients undergoing skin-sparing mastectomy compared with conventional mastectomy.

    Science.gov (United States)

    Yi, Min; Kronowitz, Steven J; Meric-Bernstam, Funda; Feig, Barry W; Symmans, W Fraser; Lucci, Anthony; Ross, Merrick I; Babiera, Gildy V; Kuerer, Henry M; Hunt, Kelly K

    2011-03-01

    Although the use of SSM is becoming more common, there are few data on long-term, local-regional, and distant recurrence rates after treatment. The purpose of this study was to examine the rates of local, regional, and systemic recurrence, and survival in breast cancer patients who underwent skin-sparing mastectomy (SSM) or conventional mastectomy (CM) at our institution. Patients with stage 0 to III unilateral breast cancer who underwent total mastectomy at our center from 2000 to 2005 were included in this study. Kaplan-Meier curves were calculated, and the log-rank test was used to evaluate the differences between overall and disease-free survival rates in the 2 groups. Of 1810 patients, 799 (44.1%) underwent SSM and 1011 (55.9%) underwent CM. Patients who underwent CM were older (58.3 vs 49.3 years, P<.0001) and were more likely to have stage IIB or III disease (53.0% vs 31.8%, P<.0001). Significantly more patients in the CM group received neoadjuvant chemotherapy and adjuvant radiation therapy (P<.0001). At a median follow-up of 53 months, 119 patients (6.6%) had local, regional, or systemic recurrences. The local, regional, and systemic recurrence rates did not differ significantly between the SSM and CM groups. After adjusting for clinical TNM stage and age, disease-free survival rates between the SSM and CM groups did not differ significantly. SSM is an acceptable treatment option for patients who are candidates for immediate breast reconstruction. Local-regional recurrence rates are similar to those of patients undergoing CM. Cancer 2011. © 2010 American Cancer Society. Copyright © 2010 American Cancer Society.

  10. Localization of oxidized low-density lipoprotein and its relation to plaque morphology in human coronary artery.

    Directory of Open Access Journals (Sweden)

    Yasumi Uchida

    Full Text Available OBJECTIVES: Oxidized low-density lipoprotein (oxLDL plays a key role in the formation of atherosclerotic plaques. However, its localization in human coronary arterial wall is not well understood. The present study was performed to visualize deposition sites and patterns of native oxLDL and their relation to plaque morphology in human coronary artery. METHODS: Evans blue dye (EB elicits a violet fluorescence by excitation at 345-nm and emission at 420-nm, and a reddish-brown fluorescence by excitation at 470-nm and emission at 515-nm characteristic of oxLDL only. Therefore, native oxLDL in excised human coronary artery were investigated by color fluorescent microscopy (CFM using EB as a biomarker. RESULTS: (1 By luminal surface scan with CFM, the % incidence of oxLDL in 38 normal segments, 41 white plaques and 32 yellow plaques that were classified by conventional angioscopy, was respectively 26, 44 and 94, indicating significantly (p<0.05 higher incidence in the latter than the former two groups. Distribution pattern was classified as patchy, diffuse and web-like. Web-like pattern was observed only in yellow plaques with necrotic core. (2 By transected surface scan, oxLDL deposited within superficial layer in normal segments and diffusely within both superficial and deep layers in white and yellow plaques. In yellow plaques with necrotic core, oxLDL deposited not only in the marginal zone of the necrotic core but also in the fibrous cap. CONCLUSION: Taken into consideration of the well-known process of coronary plaque growth, the results suggest that oxLDL begins to deposit in human coronary artery wall before plaque formation and increasingly deposits with plaque growth, exhibiting different deposition sites and patterns depending on morphological changes.

  11. Correlating the Local Defect-Level Density with the Macroscopic Composition and Energetics of Chalcopyrite Thin-Film Surfaces.

    Science.gov (United States)

    Bröker, Sebastian; Kück, Dennis; Timmer, Alexander; Lauermann, Iver; Ümsür, Bünyamin; Greiner, Dieter; Kaufmann, Christian A; Mönig, Harry

    2015-06-17

    The unusual defect chemistry of polycrystalline Cu(In,Ga)Se2 (CIGSe) thin films is a main issue for a profound understanding of recombination losses in chalcopyrite thin-film solar cells. Especially, impurity-driven passivation of electronic levels due to point defects segregating at the surface and at grain boundaries is extensively debated. By combining current imaging tunneling spectroscopy with photoelectron spectroscopy, the local defect-level density and unusual optoelectronic grain-boundary properties of this material are correlated with the macroscopic energy levels and surface composition. Vacuum annealing of different CIGSe materials provides evidence that Na diffusion from the glass substrate does not affect the surface defect passivation or grain-boundary properties of standard Cu-poor materials. Furthermore, we find no major impact on the observed thermally activated dipole compensation or the accompanying change in surface band bending (up to 0.6 eV) due to Na. In contrast, Cu-rich CIGSe shows an opposing surface defect chemistry with only minor heat-induced band bending. Our results lead to a comprehensive picture, where the highly desirable type inversion at the p/n interface in standard chalcopyrite thin-film solar cells is dominated by band bending within the CIGSe absorber rather than the result of Na impurities or an n-type defect phase segregating at the interface. This is in accordance with recent studies suggesting a surface reconstruction as the origin for Cu depletion and band-gap widening at the surface of chalcopyrite thin films.

  12. Frictional Behavior and Slip Localization in Simulated Faults of Halite at Sub-seismic to Seismic Slip Rates

    Science.gov (United States)

    Kim, J.; Ree, J.; Han, R.; Shimamoto, T.

    2007-12-01

    Halite exhibits deformation behavior ranging from brittle to plastic at room temperature and at low pressures, and has been used to simulate deformation processes of the brittle-ductile transition zone. However, previous experiments on halite were performed at very low slip rates (10-9-10-3 m/s), requiring friction data at seismic slip rates for a more complete assessment of the applicability of the experimental results to natural earthquakes. We conducted friction experiments on halite at slip rate of 0.02-1.3 m/s and normal stresses of 0.8- 10.0 MPa using a high-velocity rotary shear apparatus. A thin layer (0.6-1.0 mm thick) of halite gouge was inserted between precut rock cylinders jacketed with Teflon sleeve. We found that mechanical behavior and deformation processes of halite gouge are remarkably different depending on slip rate and that frictional melting and dislocation creep can occur simultaneously at seismic slip rates. At sub-seismic slip rates of 0.02 to 0.05 m/sec, peak friction (μp = 0.76-0.85) was followed by steady-state friction (μss = 0.35-0.37). Gouge layer consists of a thin slip localization zone at the halite gouge-rock contact and a thick low slip-rate zone. The low slip-rate zone shows evidence for cataclastic flow with angular fragments set in a fine matrix. In contrast, the slip localization zone consists of very fine gouge with some remnants of fragments. At seismic slip rates of 0.1 to 1.3 m/sec, μp (0.64-0.99) was followed by μss (0.36-0.03). μss decreases with increasing slip rate. The shear zone consists of a thin slip localization zone at the halite gouge-rock contact and a thick low slip-rate zone. The low slip-rate zone consists of polycrystalline halite ribbons highly elongated obliquely to shear zone boundary and the oblique foliation is dragged into the thin slip localization zone. Each ribbon is also defined as a lattice preferred orientation domain by electron back-scattered diffraction (EBSD) analysis. Individual

  13. Electrical source imaging and connectivity analysis to localize the seizure-onset zone based on high-density ictal scalp EEG recordings

    OpenAIRE

    Staljanssens, Willeke; Strobbe, Gregor; Van Holen, Roel; Birot, Gwenael; Michel, Christophe; Seeck, Margitta; Vulliémoz, Serge; van Mierlo, Pieter

    2015-01-01

    Functional connectivity analysis of ictal intracranial EEG (icEEG) recordings can help with seizure-onset zone (SOZ) localization in patients with focal epilepsy1. However, it would be of high clinical value to be able to localize the SOZ based on non-invasive ictal EEG recordings to better target or avoid icEEG and improve surgical outcome. In this work, we propose an approach to localize the SOZ based on non-invasive ictal high- density EEG (hd-EEG) recordings. We considered retrospectiv...

  14. Impact Localization Method for Composite Plate Based on Low Sampling Rate Embedded Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Zhuo Pang

    2017-01-01

    Full Text Available Fiber Bragg Grating (FBG sensors have been increasingly used in the field of Structural Health Monitoring (SHM in recent years. In this paper, we proposed an impact localization algorithm based on the Empirical Mode Decomposition (EMD and Particle Swarm Optimization-Support Vector Machine (PSO-SVM to achieve better localization accuracy for the FBG-embedded plate. In our method, EMD is used to extract the features of FBG signals, and PSO-SVM is then applied to automatically train a classification model for the impact localization. Meanwhile, an impact monitoring system for the FBG-embedded composites has been established to actually validate our algorithm. Moreover, the relationship between the localization accuracy and the distance from impact to the nearest sensor has also been studied. Results suggest that the localization accuracy keeps increasing and is satisfactory, ranging from 93.89% to 97.14%, on our experimental conditions with the decrease of the distance. This article reports an effective and easy-implementing method for FBG signal processing on SHM systems of the composites.

  15. Uncovering genes and ploidy involved in the high diversity in root hair density, length and response to local scarce phosphate in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Markus G Stetter

    Full Text Available Plant root hairs increase the root surface to enhance the uptake of sparingly soluble and immobile nutrients, such as the essential nutrient phosphorus, from the soil. Here, root hair traits and the response to scarce local phosphorus concentration were studied in 166 accessions of Arabidopsis thaliana using split plates. Root hair density and length were correlated, but highly variable among accessions. Surprisingly, the well-known increase in root hair density under low phosphorus was mostly restricted to genotypes that had less and shorter root hairs under P sufficient conditions. By contrast, several accessions with dense and long root hairs even had lower hair density or shorter hairs in local scarce phosphorus. Furthermore, accessions with whole-genome duplications developed more dense but phosphorus-insensitive root hairs. The impact of genome duplication on root hair density was confirmed by comparing tetraploid accessions with their diploid ancestors. Genome-wide association mapping identified candidate genes potentially involved in root hair responses tp scarce local phosphate. Knock-out mutants in identified candidate genes (CYR1, At1g32360 and RLP48 were isolated and differences in root hair traits in the mutants were confirmed. The large diversity in root hair traits among accessions and the diverse response when local phosphorus is scarce is a rich resource for further functional analyses.

  16. Influence of the overall charge and local charge density of pectin on the complex formation between pectin and beta-lactoglobulin

    NARCIS (Netherlands)

    Sperber, Bram L. H. M.; Schols, Henk A.; Stuart, Martien A. Cohen; Norde, Willem; Voragen, Alphons G. J.

    2009-01-01

    The complex formation between beta-lactoglobulin (beta-lg) and pectin is studied using pectins with different physicochemical characteristics. Pectin allows for the control of both the overall charge by degree of methyl-esterification as well as local charge density by the degree of blockiness. Vary

  17. Passive Acoustic Source Localization at a Low Sampling Rate Based on a Five-Element Cross Microphone Array

    Directory of Open Access Journals (Sweden)

    Yue Kan

    2015-06-01

    Full Text Available Accurate acoustic source localization at a low sampling rate (less than 10 kHz is still a challenging problem for small portable systems, especially for a multitasking micro-embedded system. A modification of the generalized cross-correlation (GCC method with the up-sampling (US theory is proposed and defined as the US-GCC method, which can improve the accuracy of the time delay of arrival (TDOA and source location at a low sampling rate. In this work, through the US operation, an input signal with a certain sampling rate can be converted into another signal with a higher frequency. Furthermore, the optimal interpolation factor for the US operation is derived according to localization computation time and the standard deviation (SD of target location estimations. On the one hand, simulation results show that absolute errors of the source locations based on the US-GCC method with an interpolation factor of 15 are approximately from 1/15- to 1/12-times those based on the GCC method, when the initial same sampling rates of both methods are 8 kHz. On the other hand, a simple and small portable passive acoustic source localization platform composed of a five-element cross microphone array has been designed and set up in this paper. The experiments on the established platform, which accurately locates a three-dimensional (3D near-field target at a low sampling rate demonstrate that the proposed method is workable.

  18. Adaptive local basis set for Kohn-Sham density functional theory in a discontinuous Galerkin framework II: Force, vibration, and molecular dynamics calculations

    CERN Document Server

    Zhang, Gaigong; Hu, Wei; Yang, Chao; Pask, John E

    2015-01-01

    Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn-Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of atomic forces, which can be used for a range of applications such as geometry optimization and molecular dynamics simulation. We demonstrate that, under mild assumptions, the computation of atomic forces can scale nearly linearly with the number of atoms in the system using the adaptive local basis set. We quantify the accuracy of the Hellmann-Feynman forces for a range of physical systems, benchmarked against converged planewave calculations, and find that the adaptive local basis set is efficient for both force and energy calculations, requiring at most a few tens of basis functions per atom to attain accuracy required in practice. Since the adaptive local basis set has implicit dependence on a...

  19. A local index of Maritime Continent intraseasonal variability based on rain rates over the land and sea

    Science.gov (United States)

    Vincent, C. L.; Lane, T. P.; Wheeler, M. C.

    2016-09-01

    A local index for describing intraseasonal variability over the Maritime Continent is developed. The index is based on the ratio of area-averaged rain rate over the land to that over the sea. It takes advantage of the fact that the main convective envelope of intraseasonal variability events tends to modulate the diurnal precipitation cycle over the land over the entire Maritime Continent. Lagged analysis is used to create composite intraseasonal variability events, where "day 0" is chosen according to when the normalized rain rate over the sea becomes greater than that over the land. The index identifies intraseasonal variability events associated with the Madden Julian Oscillation as well as equatorial Kelvin waves and westward propagating equatorial Rossby waves. The results suggest a similar local impact of all such events in suppressing the rain rate over land relative to that over the sea when the main convective envelope approaches.

  20. Diffusion-Based Density-Equalizing Maps: an Interdisciplinary Approach to Visualizing Homicide Rates and Other Georeferenced Statistical Data

    Science.gov (United States)

    Mazzitello, Karina I.; Candia, Julián

    2012-12-01

    In every country, public and private agencies allocate extensive funding to collect large-scale statistical data, which in turn are studied and analyzed in order to determine local, regional, national, and international policies regarding all aspects relevant to the welfare of society. One important aspect of that process is the visualization of statistical data with embedded geographical information, which most often relies on archaic methods such as maps colored according to graded scales. In this work, we apply nonstandard visualization techniques based on physical principles. We illustrate the method with recent statistics on homicide rates in Brazil and their correlation to other publicly available data. This physics-based approach provides a novel tool that can be used by interdisciplinary teams investigating statistics and model projections in a variety of fields such as economics and gross domestic product research, public health and epidemiology, sociodemographics, political science, business and marketing, and many others.

  1. Diffusion-Based Density-Equalizing Maps: an Interdisciplinary Approach to Visualizing Homicide Rates and Other Georeferenced Statistical Data

    CERN Document Server

    Mazzitello, Karina I

    2012-01-01

    In every country, public and private agencies allocate extensive funding to collect large-scale statistical data, which in turn are studied and analyzed in order to determine local, regional, national, and international policies regarding all aspects relevant to the welfare of society. One important aspect of that process is the visualization of statistical data with embedded geographical information, which most often relies on archaic methods such as maps colored according to graded scales. In this work, we apply non-standard visualization techniques based on physical principles. We illustrate the method with recent statistics on homicide rates in Brazil and their correlation to other publicly available data. This physics-based approach provides a novel tool that can be used by interdisciplinary teams investigating statistics and model projections in a variety of fields such as economics and gross domestic product research, public health and epidemiology, socio-demographics, political science, business and m...

  2. LOCAL ASYMPTOTIC PROPERTIES OF HAZARD RATE ESTIMATORS FOR TRUNCATED AND CENSORED DATA

    Institute of Scientific and Technical Information of China (English)

    SUN Liuquan; WU Guofu; WEI Xianhua

    2001-01-01

    Functional laws of the iterated logarithm are obtained for cumulative hazard processes in the neighborhood of a fixed point when the data are subject to left truncation and right censorship. On the basis of these results the exact rates of pointwise almost sure convergence for various types of kernel hazard rate estimators are derived.

  3. Ab initio quasi-particle approximation bandgaps of silicon nanowires calculated at density functional theory/local density approximation computational effort

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, M., E-mail: ribeiro.jr@oorbit.com.br [Office of Operational Research for Business Intelligence and Technology, Principal Office, Buffalo, Wyoming 82834 (United States)

    2015-06-21

    Ab initio calculations of hydrogen-passivated Si nanowires were performed using density functional theory within LDA-1/2, to account for the excited states properties. A range of diameters was calculated to draw conclusions about the ability of the method to correctly describe the main trends of bandgap, quantum confinement, and self-energy corrections versus the diameter of the nanowire. Bandgaps are predicted with excellent accuracy if compared with other theoretical results like GW, and with the experiment as well, but with a low computational cost.

  4. Local and global properties of eigenfunctions and one-electron densities of Coulombic Schrödinger operators

    DEFF Research Database (Denmark)

    Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas

    2008-01-01

    We review recent results by the authors on the regularity of molecular eigenfunctions ψ and their corresponding one-electron densities ρ, as well as of the spherically averaged one-electron atomic density ρ. Furthermore, we prove an exponentially decreasing lower bound for ρ in the case when the ...

  5. Operational specification and forecasting advances for Dst, LEO thermospheric densities, and aviation radiation dose and dose rate

    Science.gov (United States)

    Tobiska, W. Kent

    Space weather’s effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun’s photons, particles, and fields. Of the space environment domains that are affected by space weather, the magnetosphere, thermosphere, and even troposphere are key regions that are affected. Space Environment Technologies (SET) has developed and is producing innovative space weather applications. Key operational systems for providing timely information about the effects of space weather on these domains are SET’s Magnetosphere Alert and Prediction System (MAPS), LEO Alert and Prediction System (LAPS), and Automated Radiation Measurements for Aviation Safety (ARMAS) system. MAPS provides a forecast Dst index out to 6 days through the data-driven, redundant data stream Anemomilos algorithm. Anemomilos uses observational proxies for the magnitude, location, and velocity of solar ejecta events. This forecast index is used by satellite operations to characterize upcoming geomagnetic storms, for example. In addition, an ENLIL/Rice Dst prediction out to several days has also been developed and will be described. LAPS is the SET fully redundant operational system providing recent history, current epoch, and forecast solar and geomagnetic indices for use in operational versions of the JB2008 thermospheric density model. The thermospheric densities produced by that system, driven by the LAPS data, are forecast to 72-hours to provide the global mass densities for satellite operators. ARMAS is a project that has successfully demonstrated the operation of a micro dosimeter on aircraft to capture the real-time radiation environment due to Galactic Cosmic Rays and Solar Energetic Particles. The dose and dose-rates are captured on aircraft, downlinked in real-time via the Iridium satellites, processed on the ground, incorporated into the most recent NAIRAS global radiation climatology data runs, and made available to end users via the web and

  6. The rate of decay of the Wiener sausage in local Dirichlet space

    CERN Document Server

    Gibson, Lee R

    2010-01-01

    In the context of a heat kernel diffusion which admits a Gaussian type estimate with parameter beta on a local Dirichlet space, we consider the log asymptotic behavior of the negative exponential moments of the Wiener sausage. We show that the log asymptotic behavior up to time t^{beta}V(x,t) is V(x,t), which is analogous to the Euclidean result. Here V(x,t) represents the mass of the ball of radius t about a point x of the local Dirichlet space. The proof uses a known coarse graining technique to obtain the upper asymptotic, but must be adapted to for use without translation invariance in this setting. This result provides the first such asymptotics for several other contexts, including diffusions on complete Riemannian manifolds with non-negative Ricci curvature.

  7. Comparison of Local Recurrence Rate of Three Treatment Modalities for Kimura Disease.

    Science.gov (United States)

    Ye, Peng; Wei, Tai; Yu, Guang-Yan; Wu, Li-Ling; Peng, Xin

    2016-01-01

    Eosinophilic hyperplastic lymphogranuloma, also known as Kimura disease, is a benign and chronic inflammatory condition, predominantly involving the head and neck region. Surgical excision, radiotherapy (RA), surgical resection combined with low-dose postoperative radiotherapy and oral corticosteroids are 4 treatment modalities reported to control this disease effectively. Local recurrence, however, is common and the optimum treatment for Kimura disease is controversial. Thus, the present meta-analysis was performed to identify the treatment modality associated with the lowest local recurrence. Electronic databases (Cochrane Library, Wiley Online Library, PubMed, Chinese National Knowledge Infrastructure, and Wanfang Data) were searched. Data were also obtained from other sources such as related references and communication with the relevant authors. Two reviewers screened the literature according to preselected criteria. All studies involving different treatments for Kimura disease were collected. After data extraction and research quality assessment, the meta-analysis of 22 studies involving 570 patients was conducted using STATA 12.1 software. Meta-analysis revealed that administration of RA or surgical excision alone were inferior in controlling local recurrence compared with surgical resection combined with postoperative RA (risk ratio (RR) = 2.72; 95% confidence interval (CI), 1.47-5.04 and RR = 4.72; 95% CI, 2.53-8.82). Surgical excision alone did not show significant advantage in controlling local recurrence compared with RA alone (RR = 2.13; 95% CI, 0.88-5.17). Surgical resection combined with postoperative RA is superior to either surgery or RA alone in treating Kimura disease. More large scale prospective randomized controlled trials, however, should be conducted to assess the long-term effects and safety issues.

  8. A novel method to quantify local CpG methylation density by regional methylation elongation assay on microarray

    Directory of Open Access Journals (Sweden)

    Qiao Yingjuan

    2008-01-01

    Full Text Available Abstract Background DNA methylation based techniques are important tools in both clinical diagnostics and therapeutics. But most of these methods only analyze a few CpG sites in a target region. Indeed, difference of site-specific methylation may also lead to a change of methylation density in many cases, and it has been found that the density of methylation is more important than methylation of single CpG site for gene silencing. Results We have developed a novel approach for quantitative analysis of CpG methylation density on the basis of microarray-based hybridization and incorporation of Cy5-dCTP into the Cy3 labeled target DNA by using Taq DNA Polymerase on microarray. The quantification is achieved by measuring Cy5/Cy3 signal ratio which is proportional to methylation density. This methylation-sensitive technique, termed RMEAM (regional methylation elongation assay on microarray, provides several advantages over existing methods used for methylation analysis. It can determine an exact methylation density of the given region, and has potential of high throughput. We demonstrate a use of this method in determining the methylation density of the promoter region of the tumor-related gene MLH1, TERT and MGMT in colorectal carcinoma patients. Conclusion This technique allows for quantitative analysis of regional methylation density, which is the representative of all allelic methylation patterns in the sample. The results show that this technique has the characteristics of simplicity, rapidness, specificity and high-throughput.

  9. Prevalence and incidence rate of injuries in runners at a local athletic club in Cape Town

    Directory of Open Access Journals (Sweden)

    C. Hendricks

    2013-12-01

    Full Text Available People across the world are running on a daily basis to improvetheir health status. However, running can predispose an individual to injuryto the back and lower limb. Baseline data on prevalence, incidence rate ofinjury and aetiological factors associated with running injuries are neededby physiotherapists to develop and implement effective prevention programmesto allow optimal performance in runners. Thus, the purpose of this study wasto determine the prevalence and incidence of injuries in runners at a localathletic club.Methods: A prospective, non-experimental cohort study was conductedover a 16 week period. A sample of 50 runners completed a self-administeredquestionnaire and an injury report form recording injuries sustained during the 16 week study period. Injury prevalence andcumulative incidence was calculated as a proportion rate along with 95% confidence interval.Results: The prevalence rate of injuries was 32%. The incidence rate of injuries was 0.67 per 1000km run (95% CI: 0.41- 1.08.The most common anatomical sites for new injuries were the calf (20% and the knee (18%.Conclusions: The study found a moderate prevalence and incidence rate of injury in runners, thus the need for physiotherapyledinjury surveillance and prevention programmes have been highlighted.

  10. Oracle inequalities and minimax rates for non-local means and related adaptive kernel-based methods

    CERN Document Server

    Arias-Castro, Ery; Willett, Rebecca

    2011-01-01

    This paper describes a novel theoretical characterization of the performance of non-local means (NLM) for noise removal. NLM has proven effective in a variety of empirical studies, but little is understood fundamentally about how it performs relative to classical methods based on wavelets or how various parameters (e.g., patch size) should be chosen. For cartoon images and images which may contain thin features and regular textures, the error decay rates of NLM are derived and compared with those of linear filtering, oracle estimators, variable-bandwidth kernel methods, Yaroslavsky's filter and wavelet thresholding estimators. The trade-off between global and local search for matching patches is examined, and the bias reduction associated with the local polynomial regression version of NLM is analyzed. The theoretical results are validated via simulations for 2D images corrupted by additive white Gaussian noise.

  11. Topological quantum computing with a very noisy network and local error rates approaching one percent.

    Science.gov (United States)

    Nickerson, Naomi H; Li, Ying; Benjamin, Simon C

    2013-01-01

    A scalable quantum computer could be built by networking together many simple processor cells, thus avoiding the need to create a single complex structure. The difficulty is that realistic quantum links are very error prone. A solution is for cells to repeatedly communicate with each other and so purify any imperfections; however prior studies suggest that the cells themselves must then have prohibitively low internal error rates. Here we describe a method by which even error-prone cells can perform purification: groups of cells generate shared resource states, which then enable stabilization of topologically encoded data. Given a realistically noisy network (≥10% error rate) we find that our protocol can succeed provided that intra-cell error rates for initialisation, state manipulation and measurement are below 0.82%. This level of fidelity is already achievable in several laboratory systems.

  12. Electron-capture decay rate of 7Be@C60 by first-principles calculations based on density functional theory

    NARCIS (Netherlands)

    Morisato, T.; Ohno, K.; Ohtsuki, T.; Hirose, K.; Sluiter, M.; Kawazoe, Y.

    2008-01-01

    Carrying out a first-principles calculation assuming linear relationship between the electron density at Be nucleus and the electron-capture (EC) decay rate, we explained why 7Be@C60 shows higher EC decay rate than 7Be crystal, which was originally found experimentally by Ohtsuki et al. [Phys. Rev.

  13. Nano-sized structured layered positive electrode materials to enable high energy density and high rate capability lithium batteries

    Science.gov (United States)

    Deng, Haixia; Belharouak, Ilias; Amine, Khalil

    2012-10-02

    Nano-sized structured dense and spherical layered positive active materials provide high energy density and high rate capability electrodes in lithium-ion batteries. Such materials are spherical second particles made from agglomerated primary particles that are Li.sub.1+.alpha.(Ni.sub.xCo.sub.yMn.sub.z).sub.1-tM.sub.tO.sub.2-dR.sub.d- , where M is selected from can be Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, Zr, or a mixture of any two or more thereof, R is selected from F, Cl, Br, I, H, S, N, or a mixture of any two or more thereof, and 0.ltoreq..alpha..ltoreq.0.50; 0

  14. Updated results of high-dose rate brachytherapy and external beam radiotherapy for locally and locally advanced prostate cancer using the RTOG-ASTRO phoenix definition

    Directory of Open Access Journals (Sweden)

    Antonio C. Pellizzon

    2008-06-01

    Full Text Available PURPOSE: To evaluate the prognostic factors for patients with local or locally advanced prostate cancer treated with external beam radiotherapy (RT and high dose rate brachytherapy (HDR according to the RTOG-ASTRO Phoenix Consensus Conference. MATERIALS AND METHODS: The charts of 209 patients treated between 1997 and 2005 with localized RT and HDR as a boost at the Department of Radiation Oncology, AC Camargo Hospital, Sao Paulo, Brazil were reviewed. Clinical and treatment parameters i.e.: patient's age, Gleason score, clinical stage, initial PSA (iPSA, risk group (RG for biochemical failure, doses of RT and HDR were evaluated. Median age and median follow-up time were 68 and 5.3 years, respectively. Median RT and HDR doses were 45 Gy and 20 Gy. RESULTS: Disease specific survival (DSS at 3.3 year was 94.2%. Regarding RG, for the LR (low risk, IR (intermediate risk and HR (high risk, the DSS rates at 3.3 years were 91.5%, 90.2% and 88.5%, respectively. On univariate analysis prognostic factors related to DSS were RG (p = 0.040, Gleason score ≤ 6 ng/mL (p = 0.002, total dose of HDR ≥ 20 Gy (p < 0.001 On multivariate analysis the only statistical significant predictive factor for biochemical control (bNED was the RG, p < 0.001 (CI - 1.147-3.561. CONCLUSIONS: Although the radiation dose administered to the prostate is an important factor related to bNED, this could not be established with statistical significance in this group of patients. To date , in our own experience, HDR associated to RT could be considered a successful approach in the treatment of prostate cancer.

  15. Dark-bright exciton spin-flip rates of quantum dots determined by a modified local density of optical states

    DEFF Research Database (Denmark)

    Lodahl, Peter; Johansen, Jeppe; Julsgaard, Brian;

    2009-01-01

    This work investigates the influence of dark excitons on the radiative dynamics of semiconductor quantum dots (QDs). Dark excitons have total angular momentum of 2 and contribute to the fine structure of the exciton ground state. As opposed to bright excitons that have total angular momentum 1...

  16. In-situ strain localization analysis in low density transformation-twinning induced plasticity steel using digital image correlation

    Science.gov (United States)

    Eskandari, M.; Yadegari-Dehnavi, M. R.; Zarei-Hanzaki, A.; Mohtadi-Bonab, M. A.; Basu, R.; Szpunar, J. A.

    2015-04-01

    The effect of deformation temperature on the strain localization has been evaluated by an adapted digital image correlation (DIC) technique during tensile deformation. The progress of strain localization was traced by the corresponding strain maps. The electron backscatter diffraction analysis and tint etching technique were utilized to determine the impact of martensitic transformation and deformation twinning on the strain localization in both elastic and plastic regimes. In elastic regime the narrow strain bands which are aligned perpendicular to the tension direction were observed in temperature range of 25 to 180 °C due to the stress-assisted epsilon martensite. The strain bands were disappeared by increasing the temperature to 300 °C and reappeared at 400 °C due to the stress-assisted deformation twinning. In plastic regime strain localization continued at 25 °C and 180 °C due to the strain-induced alfa-martensite and deformation twinning, respectively. The intensity of plastic strain localization was increased by increasing the strain due to the enhancement of martensite and twin volume fraction. The plastic strain showed more homogeneity at 300 °C due to the lack of both strain-induced martensite and deformation twinning. Effect of deformation mechanism by changing temperature on strain localization is investigated by digital image correlation. EBSD technique is served to validate deformation mechanism as well as microstructural evolution. Strain induced martensite as well as deformation twinning is activated in the present steel affecting strain localization.

  17. 34 CFR 222.69 - What tax rates may the Secretary use if substantial local revenues are derived from local tax...

    Science.gov (United States)

    2010-07-01

    ... local revenues are derived from local tax sources other than real property taxes? 222.69 Section 222.69... substantial local revenues are derived from local tax sources other than real property taxes? (a) In a State... derived from local tax sources other than real property taxes, the State educational agency (SEA)...

  18. Using van Hove singularities of the two-phonon density of states to investigate the intrinsically localized vibrations of NaI crystal.

    Science.gov (United States)

    Agyare, Benjamin; Riseborough, Peter

    2017-01-01

    Intrinsically Localized Modes (ILMs) have purportedly been observed in NaI but only for wave-vectors, q at the corner of the 3-D Brillouin Zone. It has been suggested that, for high-symmetry q vectors, several van Hove singularities may converge at one frequency producing a large peak in the two-phonon density of state and giving rise to ILMs with these q values. We fit the experimentally determined acoustic and the optic phonon modes using a nearest neighbor and a next-nearest neighbor force constant. We find that the two-phonon density of states, for fixed q exhibits non-divergent van Hove singularities. The frequencies of these features are found to vary as q is varied. We intend to search for q values at which the two-phonon density of states is enhanced and then examine whether the anharmonic interactions can bind the two-phonon excitations to produce a quantized ILM.

  19. High-Dose-Rate Brachytherapy Boost Effect on Local Tumor Control in Young Women With Breast Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Guinot, Jose-Luis, E-mail: jguinot@fivo.org [Department of Radiation Oncology, Fundacion Instituto Valenciano de Oncologia, Valencia (Spain); Baixauli-Perez, Cristobal [Health Services Research Unit, Center for Public Health Research, Valencia (Spain); Soler, Pablo; Tortajada, Maria Isabel; Moreno, Araceli; Santos, Miguel Angel; Mut, Alejandro [Department of Radiation Oncology, Fundacion Instituto Valenciano de Oncologia, Valencia (Spain); Gozalbo, Francisco [Department of Pathology, Fundacion Instituto Valenciano de Oncologia, Valencia (Spain); Arribas, Leoncio [Department of Radiation Oncology, Fundacion Instituto Valenciano de Oncologia, Valencia (Spain)

    2015-01-01

    Purpose: To evaluate the local control rate and complications of a single fraction of high-dose-rate brachytherapy (HDR BT) boost in women aged 45 yeas and younger after breast-conserving therapy. Methods and Materials: Between 1999 and 2007, 167 patients between the ages of 26 and 45 years old (72 were 40 years old or younger), with stages T1 to T2 invasive breast cancer with disease-free margin status of at least 5 mm after breast-conserving surgery received 46 to 50 Gy whole-breast irradiation plus a 7-Gy HDR-BT boost (“fast boost”). An axillary dissection was performed in 72.5% of the patients and sentinel lymph node biopsy in 27.5%. A supraclavicular area was irradiated in 19% of the patients. Chemotherapy was used in 86% of the patients and hormone treatment in 77%. Clinical nodes were present in 18% and pathological nodes in 29%. The pathological stage was pT0: 5%, pTis: 3%, pT1: 69% and pT2: 23%. Intraductal component was present in 40% and 28% were G3. Results: At a median follow-up of 92 months, 9 patients relapsed on the margin of the implant, and 1 patient in another quadrant, resulting in a 10-year local relapse rate of 4.3% and a breast relapse rate of 4.9%, with breast preservation in 93.4%; no case of mastectomy due to poor cosmesis arose. Actuarial 5- and 10-year disease-free, cause-specific, and overall survival rates were 87.9% and 85.8%, and 92.1% and 88.4%, and 92.1% and 87.3%, respectively. In a univariate analysis, triple-negative cases and negative hormone receptors did worse, but in a multivariate analysis, only the last factor was significant for local and breast control. Asymptomatic fibrosis G2 was recorded in 3 cases, and there were no other late complications. Cosmetic results were good to excellent in 97% of cases. Conclusions: A single dose of 7 Gy using the fast-boost technique is well tolerated, with a low rate of late complications and improved local tumor control in women aged 45 and younger, compared to published data

  20. Characterization of the local density-of-states fluctuations near the integer quantum Hall transition in a quantum-dot array

    Science.gov (United States)

    Jug, Giancarlo; Ziegler, Klaus

    1997-10-01

    We present a calculation for the second moment of the local density of states in a model of a two-dimensional quantum dot array near the quantum Hall transition. The quantum dot array model is a realistic adaptation of the lattice model for the quantum Hall transition in the two-dimensional electron gas in an external magnetic field proposed by Ludwig, Fisher, Shankar, and Grinstein. We make use of a Dirac fermion representation for the Green's functions in the presence of fluctuations for the quantum dot energy levels. A saddle-point approximation yields nonperturbative results for the first and second moments of the local density of states, showing interesting fluctuation behavior near the quantum Hall transition. To our knowledge we discuss here one of the first analytic characterizations of chaotic behavior for a two-dimensional mesoscopic structure. The connection with possible experimental investigations of the local density of states in the quantum dot array structures (by means of NMR Knight-shift or single-electron-tunneling techniques) and our work is also established.

  1. Streptococcal serum opacity factor increases the rate of hepatocyte uptake of human plasma high-density lipoprotein cholesterol.

    Science.gov (United States)

    Gillard, Baiba K; Rosales, Corina; Pillai, Biju K; Lin, Hu Yu; Courtney, Harry S; Pownall, Henry J

    2010-11-16

    Serum opacity factor (SOF), a virulence determinant of Streptococcus pyogenes, converts plasma high-density lipoproteins (HDL) to three distinct species: lipid-free apolipoprotein (apo) A-I, neo HDL, a small discoidal HDL-like particle, and a large cholesteryl ester-rich microemulsion (CERM) that contains the cholesterol esters (CE) of up to ∼400000 HDL particles and apo E as its major protein. Similar SOF reaction products are obtained with HDL, total plasma lipoproteins, and whole plasma. We hypothesized that hepatic uptake of CERM-CE via multiple apo E-dependent receptors would be faster than that of HDL-CE. We tested our hypothesis using human hepatoma cells and lipoprotein receptor-specific Chinese hamster ovary (CHO) cells. The uptake of [(3)H]CE by HepG2 and Huh7 cells from HDL after SOF treatment, which transfers >90% of HDL-CE to CERM, was 2.4 and 4.5 times faster, respectively, than from control HDL. CERM-[(3)H]CE uptake was inhibited by LDL and HDL, suggestive of uptake by both the LDL receptor (LDL-R) and scavenger receptor class B type I (SR-BI). Studies in CHO cells specifically expressing LDL-R and SR-BI confirmed CERM-[(3)H]CE uptake by both receptors. RAP and heparin inhibit CERM-[(3)H]CE but not HDL-[(3)H]CE uptake, thereby implicating LRP-1 and cell surface proteoglycans in this process. These data demonstrate that SOF treatment of HDL increases the rate of CE uptake via multiple hepatic apo E receptors. In so doing, SOF might increase the level of hepatic disposal of plasma cholesterol in a way that is therapeutically useful.

  2. Improving local PCA in pseudo phase space for fetal heart rate estimation from single lead abdominal ECG.

    Science.gov (United States)

    Wei, Zheng; Hongxing, Liu; Jianchun, Cheng

    2011-12-01

    This paper proposes an improved local principal component analysis (LPCA) in pseudo phase space for fetal heart rate estimation from a single lead abdominal ECG signal. The improved LPCA process can extract both the maternal ECG component and the fetal ECG component in an abdominal signal. The instantaneous fetal heart rate can then be estimated from the extracted fetal ECG waveform. Compared with the classical LPCA procedure and another single lead based fetal heart rate estimation method, our improved LPCA method has shown better robustness and efficiency in fetal heart estimation, testing with synthetic ECG signals and a real fetal ECG database from PhysioBank. For the real fetal ECG validating dataset of six long-duration recordings (obtained between the 22(nd) and 40(th) week of gestation), the average accuracy of the improved LPCA method is 84.1%.

  3. Significance of vapor phase chemical reactions on CVD rates predicted by chemically frozen and local thermochemical equilibrium boundary layer theories

    Science.gov (United States)

    Gokoglu, Suleyman A.

    1988-01-01

    This paper investigates the role played by vapor-phase chemical reactions on CVD rates by comparing the results of two extreme theories developed to predict CVD mass transport rates in the absence of interfacial kinetic barrier: one based on chemically frozen boundary layer and the other based on local thermochemical equilibrium. Both theories consider laminar convective-diffusion boundary layers at high Reynolds numbers and include thermal (Soret) diffusion and variable property effects. As an example, Na2SO4 deposition was studied. It was found that gas phase reactions have no important role on Na2SO4 deposition rates and on the predictions of the theories. The implications of the predictions of the two theories to other CVD systems are discussed.

  4. Optimizing finite element predictions of local subchondral bone structural stiffness using neural network-derived density-modulus relationships for proximal tibial subchondral cortical and trabecular bone.

    Science.gov (United States)

    Nazemi, S Majid; Amini, Morteza; Kontulainen, Saija A; Milner, Jaques S; Holdsworth, David W; Masri, Bassam A; Wilson, David R; Johnston, James D

    2017-01-01

    Quantitative computed tomography based subject-specific finite element modeling has potential to clarify the role of subchondral bone alterations in knee osteoarthritis initiation, progression, and pain. However, it is unclear what density-modulus equation(s) should be applied with subchondral cortical and subchondral trabecular bone when constructing finite element models of the tibia. Using a novel approach applying neural networks, optimization, and back-calculation against in situ experimental testing results, the objective of this study was to identify subchondral-specific equations that optimized finite element predictions of local structural stiffness at the proximal tibial subchondral surface. Thirteen proximal tibial compartments were imaged via quantitative computed tomography. Imaged bone mineral density was converted to elastic moduli using multiple density-modulus equations (93 total variations) then mapped to corresponding finite element models. For each variation, root mean squared error was calculated between finite element prediction and in situ measured stiffness at 47 indentation sites. Resulting errors were used to train an artificial neural network, which provided an unlimited number of model variations, with corresponding error, for predicting stiffness at the subchondral bone surface. Nelder-Mead optimization was used to identify optimum density-modulus equations for predicting stiffness. Finite element modeling predicted 81% of experimental stiffness variance (with 10.5% error) using optimized equations for subchondral cortical and trabecular bone differentiated with a 0.5g/cm(3) density. In comparison with published density-modulus relationships, optimized equations offered improved predictions of local subchondral structural stiffness. Further research is needed with anisotropy inclusion, a smaller voxel size and de-blurring algorithms to improve predictions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Radiation therapy for localized prostate cancer. For high-dose rate conformal brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kinugawa, Keigo; Jo, Yoshimasa; Morioka, Masaaki; Tanaka, Hiroyoshi; Hiratsuka, Junichi; Imajo, Yoshinari [Kawasaki Medical School, Kurashiki, Okayama (Japan)

    1999-05-01

    Sixteen patients with localized prostate cancer were referred to our clinic for radiation therapy in combination with HDR brachytherapy using Ir-192 pellets between October 1997 and August 1998. The patients were given external beam radiation of 45 Gy to the whole pelvis in combination with an interstitial HDR brachytherapy implant of 3 fractions each delivering 5.5 Gy during two days. Using an implanting device especially designed for HDR, 10-18 applicator needles (17 gauge) were implanted into the prostate using transrectal ultrasound (TRUS) with perineal template guidance under spinal anesthesia. Pathological evaluation was performed at 6 months after treatment. This technique of external beam radiation combined with HDR brachytherapy was well tolerated. Serum prostatic antigen (PSA) levels became normalized in 87.5% of the patients (14 out of 16) within 1-14 months (median 2 months) after the irradiation. No significant intraoperative or perioperative complications occurred, however one patient (6.25%) experienced Grade 3 hematuria. Most of the early complications were otherwise Grade 1 or 2. From prospectively planned prostatic rebiopsies performed at 6 months, we can observe the radiation effects in the pathological findings such as fibrosis, basal cell hyperplasia, bizarre cells and intraductal calcifications. (K.H.)

  6. Relationship between severity of the local skin reactions and the rate of local skin reaction resolution in patients treated with ingenol mebutate gel

    Directory of Open Access Journals (Sweden)

    Jim On SC

    2016-08-01

    Full Text Available Shelbi C Jim On,1 Kim Mark Knudsen,2 Torsten Skov,2 Mark Lebwohl,1 1Department of Dermatology, Mount Sinai School of Medicine, New York, NY, USA; 2LEO Pharma A/S, Biostatistics, Ballerup, Denmark Background: Ingenol mebutate gel is a topical field treatment for actinic keratosis (AK. The treatment elicits application-site reactions in most patients. This analysis evaluated the relationship between the severity of reactions and the speed of their resolution.  Methods: Patients in Phase III studies were treated for AKs on the face (n=218, scalp (n=56, and trunk and extremities (n=209. All of the patients were treated with either ingenol mebutate gel 0.015% once daily for three consecutive days (face/scalp or ingenol mebutate gel 0.05% once daily for two consecutive days (trunk/extremities. Local skin reactions (LSRs were assessed on a 5-point scale from 0 to 4 in six categories, yielding composite scores in the range of 0 to 24. Results: The composite LSR score on the day after the last application of ingenol mebutate gel was an important predictor of the speed of resolution of LSRs. The rate of resolution was greatest for AKs treated on the face, followed by the scalp, and then the trunk and extremities. All patients were expected to have minimal LSR scores for the face and scalp at 2 weeks, and for the trunk and extremities at 4 weeks. Conclusion: The absolute reduction in LSR scores was proportional to the composite LSR score on the day after the last application of ingenol mebutate gel treatment. The rate of resolution for LSRs was dependent on the anatomic site treated as well as the day 4 composite score. Keywords: ingenol mebutate, local skin reaction, actinic keratosis

  7. Local cooling effect on perforation rates comparing the 980-1470 nm laser wavelengths used with endovenous laser ablation: double blind in vitro experimental study.

    Science.gov (United States)

    Tarhan, I A; Dumantepe, M; Yurdakul, I; Kehlibar, T; Ozler, A

    2014-03-01

    Endovenous laser treatment (EVLA) is fast gaining acceptance as an alternative to open surgery for the treatment of saphenous vein incompetence. The method of action of these techniques is based on heat, making tumescence anaesthesia necessity. Heat-induced complications may occur with inadequate application of tumescent anaesthesia. Our hypothesis was, local cooling effect of tumescent anaesthesia on tunica adventitia might be kept undamaged from disruption due to the thermal injury. We experimented with two popular laser wavelengths (980 and 1470 nm) and with two different thermal media (+4 and +24) in vitro for perforation. Twenty different 12 cm length vein pieces were numbered randomly to set up four groups of the experiment. Endovenous laser procedures were applied in same manner in a unique design test tube with same energy density per pieces on same duration (10 W/second) (linear endovenous energy density 60 J/cm). Procedure video was recorded for macroscopic perforations. All postprocedure vein segments were examined microscopically. Activities of both wavelengths were much better in cold medium (P laser was better than that of 980 nm in cold environment (P = 0.0136). It can be commented that reducing the ambient temperature is more beneficial than modifying the laser wavelength on perforation rates. Therefore we suppose tumescent anaesthesia temperature is effective on perforation independently from the wavelengths or type of the laser fibre.

  8. ELUCID - Exploring the Local Universe with reConstructed Initial Density field III: Constrained Simulation in the SDSS Volume

    CERN Document Server

    Wang, Huiyuan; Yang, Xiaohu; Zhang, Youcai; Shi, JingJing; Jing, Y P; Liu, Chengze; Li, Shijie; Kang, Xi; Gao, Yang

    2016-01-01

    A method we developed recently for the reconstruction of the initial density field in the nearby Universe is applied to the Sloan Digital Sky Survey Data Release 7. A high-resolution N-body constrained simulation (CS) of the reconstructed initial condition, with $3072^3$ particles evolved in a 500 Mpc/h box, is carried out and analyzed in terms of the statistical properties of the final density field and its relation with the distribution of SDSS galaxies. We find that the statistical properties of the cosmic web and the halo populations are accurately reproduced in the CS. The galaxy density field is strongly correlated with the CS density field, with a bias that depend on both galaxy luminosity and color. Our further investigations show that the CS provides robust quantities describing the environments within which the observed galaxies and galaxy systems reside. Cosmic variance is greatly reduced in the CS so that the statistical uncertainties can be controlled effectively even for samples of small volumes...

  9. Two dimensional localization of electrons and positrons under high counting rate

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, A.F.; Anjos, J.C.; Sanchez-Hernandez, A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Pepe, I.M.; Barros, N. [Bahia Univ., Salvador, BA (Brazil). Inst. de Fisica

    1997-12-01

    The construction of two wire chambers for the experiment E831 at Fermilab is reported. Each chamber includes three wire planes - one anode and two orthogonal cathodes - in which the wires operate as independent proportional counters. One of the chambers is rotated with respect to the other, so that four position coordinates may be encoded for a charged particle crossing both chambers. Spatial resolution is determined by the wire pitch: 1 mm for cathodes, 2 mm for anodes. 320 electronic channels are involved in the detection system readout. Global counting rates in excess to 10{sup 7} events per second have been measured, while the average electron-positron beam intensity may be as high as 3 x 10{sup 7} events per second. (author) 5 refs., 9 figs.

  10. Evaluation of Spatial Resolution and Noise Sensitivity of sLORETA Method for EEG Source Localization Using Low-Density Headsets

    CERN Document Server

    Saha, Sajib; Tahtali, Murat; Gureyev, Timur E

    2014-01-01

    Electroencephalography (EEG) has enjoyed considerable attention over the past century and has been applied for diagnosis of epilepsy, stroke, traumatic brain injury and other disorders where 3D localization of electrical activity in the brain is potentially of great diagnostic value. In this study we evaluate the precision and accuracy of spatial localization of electrical activity in the brain delivered by a popular reconstruction technique sLORETA applied to EEG data collected by two commonly used low-density headsets with 14 and 19 measurement channels, respectively. Numerical experiments were performed for a realistic head model obtained by segmentation of MRI images. The EEG source localization study was conducted with a simulated single active dipole, as well as with two spatially separated simultaneously active dipoles, as a function of dipole positions across the neocortex, with several different noise levels in the EEG signals registered on the scalp. The results indicate that while the reconstructio...

  11. Local shear texture formation in adiabatic shear bands by high rate compression of high manganese TRIP steels

    Science.gov (United States)

    Li, J.; Yang, P.; Mao, W. M.; Cui, F. E.

    2015-04-01

    Local shear textures in ASBs of high manganese TRIP steels under high rate straining are determined and the influences of initial microstructure is analyzed using EBSD technique. It is seen that even at the presence of majority of two types of martensite before deformation, ASB is preferred to evolve in austenite, rather than in martenite, due to reverse transformation. Ultrafine grains of thress phases due to dynamic recrystallization are formed and all show shear textures. The less ε-martensite in ASB is distributed as islands and its preferred orientation can be found to originate from the variants in matrix. The grain orientation rotation around ASB in multi-phase alloy reveals significant influence of α'- martensite on texture in ASB. The mechanism of local texture formation in ASB of high manganese TRIP steel is proposed in terms of the interaction of early TRIP and later reverse transformation.

  12. Block-Localized Density Functional Theory (BLDFT), Diabatic Coupling, and Their Use in Valence Bond Theory for Representing Reactive Potential Energy Surfaces.

    Science.gov (United States)

    Cembran, Alessandro; Song, Lingchun; Mo, Yirong; Gao, Jiali

    2009-10-13

    A multistate density functional theory in the framework of the valence bond model is described. The method is based on a block-localized density functional theory (BLDFT) for the construction of valence-bond-like diabatic electronic states and is suitable for the study of electron transfer reactions and for the representation of reactive potential energy surfaces. The method is equivalent to a valence bond theory with the treatment of the localized configurations by using density functional theory (VBDFT). In VBDFT, the electron densities and energies of the valence bond states are determined by BLDFT. A functional estimate of the off-diagonal matrix elements of the VB Hamiltonian is proposed, making use of the overlap integral between Kohn-Sham determinants and the exchange-correlation functional for the ground state substituted with the transition (exchange) density. In addition, we describe an approximate approach, in which the off-diagonal matrix element is computed by wave function theory using block-localized Kohn-Sham orbitals. The key feature is that the electron density of the adiabatic ground state is not directly computed nor used to obtain the ground-state energy; the energy is determined by diagonalization of the multistate valence bond Hamiltonian. This represents a departure from the standard single-determinant Kohn-Sham density functional theory. The multistate VBDFT method is illustrated by the bond dissociation of H2+ and a set of three nucleophilic substitution reactions in the DBH24 database. In the dissociation of H2+, the VBDFT method yields the correct asymptotic behavior as the two protons stretch to infinity, whereas approximate functionals fail badly. For the S(N)2 nucleophilic substitution reactions, the hybrid functional B3LYP severely underestimates the barrier heights, while the approximate two-state VBDFT method overcomes the self-interaction error, and overestimates the barrier heights. Inclusion of the ionic state in a three

  13. High-dose-rate intraluminal brachytherapy prior to external radiochemotherapy in locally advanced esophageal cancer: preliminary results.

    Science.gov (United States)

    Safaei, Afsaneh Maddah; Ghalehtaki, Reza; Khanjani, Nezhat; Farazmand, Borna; Babaei, Mohammad; Esmati, Ebrahim

    2017-02-01

    Dysphagia is a common initial presentation in locally advanced esophageal cancer and negatively impacts patient quality of life and treatment compliance. To induce fast relief of dysphagia in patients with potentially operable esophageal cancer high-dose-rate (HDR) brachytherapy was applied prior to definitive radiochemotherapy. In this single arm phase II clinical trial between 2013 to 2014 twenty patients with locally advanced esophageal cancer (17 squamous cell and 3 adenocarcinoma) were treated with upfront 10 Gy HDR brachytherapy, followed by 50.4 Gy external beam radiotherapy (EBRT) and concurrent chemotherapy with cisplatin/5-fluorouracil. Tumor response, as measured by endoscopy and/or computed tomography scan, revealed complete remission in 16 and partial response in 4 patients (overall response rate 100%). Improvement of dysphagia was induced by brachytherapy within a few days and maintained up to the end of treatment in 80% of patients. No differences in either response rate or dysphagia resolution were found between squamous cell and adenocarcinoma histology. The grade 2 and 3 acute pancytopenia or bicytopenia reported in 4 patients, while sub-acute adverse effects with painful ulceration was seen in five patients, occurring after a median of 2 months. A perforation developed in one patient during the procedure of brachytherapy that resolved successfully with immediate surgery. Brachytherapy before EBRT was a safe and effective procedure to induce rapid and durable relief from dysphagia, especially when combined with EBRT.

  14. Coupled-cluster, Möller Plesset (MP2), density fitted local MP2, and density functional theory examination of the energetic and structural features of hydrophobic solvation: water and pentane.

    Science.gov (United States)

    Ghadar, Yasaman; Clark, Aurora E

    2012-02-07

    The interaction potentials between immiscible polar and non-polar solvents are a major driving force behind the formation of liquid:liquid interfaces. In this work, the interaction energy of water-pentane dimer has been determined using coupled-cluster theory with single double (triple) excitations [CCSD(T)], 2nd order Möller Plesset perturbation theory (MP2), density fitted local MP2 (DF-LMP2), as well as density functional theory using a wide variety of density functionals and several different basis sets. The M05-2X exchange correlation functionals exhibit excellent agreement with CCSD(T) and DF-LMP2 after taking into account basis set superposition error. The gas phase water-pentane interaction energy is found to be quite sensitive to the specific pentane isomer (2,2-dimethylpropane vs. n-pentane) and relative orientation of the monomeric constituents. Subsequent solution phase cluster calculations of 2,2-dimethylpropane and n-pentane solvated by water indicate a positive free energy of solvation that is in good agreement with available experimental data. Structural parameters are quite sensitive to the density functional employed and reflect differences in the two-body interaction energy calculated by each method. In contrast, cluster calculations of pentane solvation of H(2)O solute are found to be inadequate for describing the organic solvent, likely due to limitations associated with the functionals employed (B3LYP, BHandH, and M05-2X).

  15. 34 CFR 694.9 - What is the maximum indirect cost rate for an agency of a State or local government?

    Science.gov (United States)

    2010-07-01

    ... for an agency of a State or local government? Notwithstanding 34 CFR 75.560-75.562 and 34 CFR 80.22, the maximum indirect cost rate that an agency of a State or local government receiving funds under... a State or local government? 694.9 Section 694.9 Education Regulations of the Offices of...

  16. Experimental research on the mixed sand ratio and initial dry density of weathered sand improved expansive soil free load swelling rate

    Institute of Scientific and Technical Information of China (English)

    Yang Jun; Yang Zhi; Zhang Guodong; Tang Yunwei; Chen Hongping

    2014-01-01

    In this paper, through the indoor free load swelling rate test, expansive soil in a section of a first- class highway reconstruction project in Yichang City was studied. It emphatically analyzed the interrelations among free load swelling rate, non-load time, the proportion of mixed sand and initial dry density. Experimen- tal studies have shown that: Free load swelling deformation is mainly divided into three stages of rapid expan- sion, slow expansion and final stability; when the initial dry density is constant, free load swelling rate of the weathered sand modified soil will reduce rapidly before they slow down with the increase of sand proportion, and weathered sand modified soil free load swelling rate is not sensitive to the large amount of sand mixed; in the same mixed sand ratio, weathered sand modified soil free load swelling rate increases rapidly with the in- crease of initial dry density, there is a good linear correlation between them. To take appropriate control of the initial dry density during the expansive soil subgrade construction helps to reduce its swelling deformation and ensures the stability of the embankment.

  17. The role of magnetic islands in modifying long range temporal correlations of density fluctuations and local heat transport

    CERN Document Server

    van Milligen, B Ph; Garcia, L; Bruna, D Lopez; Carreras, B A; Xu, Y; Ochando, M; Hidalgo, C; Reynolds-Barredo, J M; Fraguas, A Lopez

    2016-01-01

    This work explores the relation between magnetic islands, long range temporal correlations and heat transport. A low order rational surface ($\\iota/2\\pi = 3/2$) was purposely scanned outward through an Electron Cyclotron Resonance Heated (ECRH) plasma in the TJ-II stellarator. Density turbulence and the poloidal flow velocity (or radial electric field) were characterized using a two channel Doppler Reflectometer. Simultaneously, the ECRH power was modulated to characterize heat transport, using measurements from a 12 channel Electron Cyclotron Emission diagnostic. A systematic variation of the poloidal velocity was found to be associated with the stationary $\\iota/2\\pi = 3/2$ magnetic island. Inside from the rational surface, the Hurst coefficient, quantifying the nature of long-range correlations, was found to be significantly enhanced. Simultaneously, heat transport was enhanced as well, establishing a clear link between density fluctuations and anomalous heat transport. The variation of the Hurst coefficie...

  18. Derivation of the Fano profile from time-dependent density-functional theory for local thermodynamic equilibrium plasmas

    Science.gov (United States)

    Kiyokawa, Shuji

    2007-04-01

    We give the derivation of the Fano profile (the resonance energy position, the resonance width Γ , and q value) from the time-dependent nonrelativistic density-functional theory (DFT) and propose a scheme for calculating the photoabsorption cross section of hot dense plasmas. As a consequence of this derivation, we show the line profile is obtained as a superposition of Fano and Lorentz profiles when the competition of two optically allowed bound-bound and bound-free transitions occurs. We also show the results of the photoabsorption cross section by applying our scheme to an Fe plasma (density is 7.85g/cm3 , temperature is 100eV ), where the calculation is carried out without numerical divergence for any photon energy. The calculated results are in good agreement with those of Grimaldi.

  19. Solving Local Minima Problem in Back Propagation Algorithm Using Adaptive Gain, Adaptive Momentum and Adaptive Learning Rate on Classification Problems

    Science.gov (United States)

    Hamid, Norhamreeza Abdul; Nawi, Nazri Mohd; Ghazali, Rozaida; Salleh, Mohd Najib Mohd

    This paper presents a new method to improve back propagation algorithm from getting stuck with local minima problem and slow convergence speeds which caused by neuron saturation in the hidden layer. In this proposed algorithm, each training pattern has its own activation functions of neurons in the hidden layer that are adjusted by the adaptation of gain parameters together with adaptive momentum and learning rate value during the learning process. The efficiency of the proposed algorithm is compared with the conventional back propagation gradient descent and the current working back propagation gradient descent with adaptive gain by means of simulation on three benchmark problems namely iris, glass and thyroid.

  20. Revision of single atom local density and capture number varying with coverage in uniform depletion approximation and its effect on coalescence and number of stable clusters

    Institute of Scientific and Technical Information of China (English)

    Shao Qing-Yi; Zhang Juan

    2011-01-01

    In vapour deposition,single atoms(adatoms)on the substrate surface are the main source of growth.The change in its density plays a decisive role in the growth of thin films and quantum size islands.In the nucleation and cluster coalescence stages of vapour deposition,the growth of stable clusters occurs on the substrate surface covered by stable clusters.Nucleation occurs in the non-covered part,while the total area covered by stable clusters on the substrate surface will gradually increase.Carefully taking into account the coverage effect,a revised single atom density rate equation is given for the famous and widely used thin-film rate equation theory,but the work of solving the revised equation has not been done.In this paper,we solve the equation and obtain the single-atom density and capture number by using a uniform depletion approximation.We determine that the single atom density is much lower than that evaluated from the single atom density rate equation in the traditional rate equation theory when the stable cluster coverage fraction is large,and it goes down very fast with an increase in the coverage fraction.The revised equation gives a higher value for the 'average' capture number than the present equation. It also increases with increasing coverage.That makes the preparation of single crystalline thin film materials difficult and the size control of quantum size islands complicated.We also discuss the effect of the revision on coalescence and the number of stable clusters in vapour deposition.

  1. Dosimetric Evaluation of High-Dose-Rate Interstitial Brachytherapy Boost Treatments for Localized Prostate Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Froehlich, Georgina [Semmelweis Univ., Budapest (Hungary); Dept. of Radiotherapy, National Inst. of Oncology, Budapest (Hungary); Agoston, Peter; Loevey, Jozsef; Somogyi, Andras; Fodor, Janos; Polgar, Csaba; Major, Tibor [Dept. of Radiotherapy, National Inst. of Oncology, Budapest (Hungary)

    2010-07-15

    Purpose: to quantitatively evaluate the dose distributions of high-dose-rate (HDR) prostate implants regarding target coverage, dose homogeneity, and dose to organs at risk. Material and methods: treatment plans of 174 implants were evaluated using cumulative dose-volume histograms (DVHs). The planning was based on transrectal ultrasound (US) imaging, and the prescribed dose (100%) was 10 Gy. The tolerance doses to rectum and urethra were 80% and 120%, respectively. Dose-volume parameters for target (V90, V100, V150, V200, D90, D{sub min}) and quality indices (DNR [dose nonuniformity ratio], DHI [dose homogeneity index], CI [coverage index], COIN [conformal index]) were calculated. Maximum dose in reference points of rectum (D{sub r}) and urethra (D{sub u}), dose to volume of 2 cm{sup 3} of the rectum (D{sub 2ccm}), and 0.1 cm{sup 3} and 1% of the urethra (D{sub 0.1ccm} and D1) were determined. Nonparametric correlation analysis was performed between these parameters. Results: the median number of needles was 16, the mean prostate volume (V{sub p}) was 27.1 cm{sup 3}. The mean V90, V100, V150, and V200 were 90%, 97%, 39% and 13%, respectively. The mean D90 was 109%, and the D{sub min} was 87%. The mean doses in rectum and urethra reference points were 75% and 119%, respectively. The mean volumetric doses were D{sub 2ccm} = 49% for the rectum, D{sub 0.1ccm} = 126%, and D1 = 140% for the urethra. The mean DNR was 0.37, while the DHI was 0.60. The mean COIN was 0.66. The Spearman rank order correlation coefficients for volume doses to rectum and urethra were R(D{sub r}, D{sub 2ccm}) = 0.69, R(D{sub u}, D{sub 0.1ccm}) = 0.64, R(D{sub u}, D1) = 0.23. Conclusion: US-based treatment plans for HDR prostate implants based on the real positions of catheters provided acceptable dose distributions. In the majority of the cases, the doses to urethra and rectum were kept below the defined tolerance levels. For rectum, the dose in reference points correlated well with dose

  2. Vermicomposting of source-separated human faeces by Eisenia fetida: effect of stocking density on feed consumption rate, growth characteristics and vermicompost production.

    Science.gov (United States)

    Yadav, Kunwar D; Tare, Vinod; Ahammed, M Mansoor

    2011-06-01

    The main objective of the present study was to determine the optimum stocking density for feed consumption rate, biomass growth and reproduction of earthworm Eisenia fetida as well as determining and characterising vermicompost quantity and product, respectively, during vermicomposting of source-separated human faeces. For this, a number of experiments spanning up to 3 months were conducted using soil and vermicompost as support materials. Stocking density in the range of 0.25-5.00 kg/m(2) was employed in different tests. The results showed that 0.40-0.45 kg-feed/kg-worm/day was the maximum feed consumption rate by E. fetida in human faeces. The optimum stocking densities were 3.00 kg/m(2) for bioconversion of human faeces to vermicompost, and 0.50 kg/m(2) for earthworm biomass growth and reproduction.

  3. Energy Decomposition Analysis Based on Absolutely Localized Molecular Orbitals for Large-Scale Density Functional Theory Calculations in Drug Design.

    Science.gov (United States)

    Phipps, M J S; Fox, T; Tautermann, C S; Skylaris, C-K

    2016-07-12

    We report the development and implementation of an energy decomposition analysis (EDA) scheme in the ONETEP linear-scaling electronic structure package. Our approach is hybrid as it combines the localized molecular orbital EDA (Su, P.; Li, H. J. Chem. Phys., 2009, 131, 014102) and the absolutely localized molecular orbital EDA (Khaliullin, R. Z.; et al. J. Phys. Chem. A, 2007, 111, 8753-8765) to partition the intermolecular interaction energy into chemically distinct components (electrostatic, exchange, correlation, Pauli repulsion, polarization, and charge transfer). Limitations shared in EDA approaches such as the issue of basis set dependence in polarization and charge transfer are discussed, and a remedy to this problem is proposed that exploits the strictly localized property of the ONETEP orbitals. Our method is validated on a range of complexes with interactions relevant to drug design. We demonstrate the capabilities for large-scale calculations with our approach on complexes of thrombin with an inhibitor comprised of up to 4975 atoms. Given the capability of ONETEP for large-scale calculations, such as on entire proteins, we expect that our EDA scheme can be applied in a large range of biomolecular problems, especially in the context of drug design.

  4. Local states in one-dimensional CDW (charge density wave) materials: Spectral signatures for polarons and bipolarons in MX chains

    Energy Technology Data Exchange (ETDEWEB)

    Swanson, B. I.; Donohoe, R. J.; Worl, L. A.; Bulou, A. D.F.; Arrington, C. A.; Gammel, J. T.; Saxena, A.; Bishop, A. R.

    1990-01-01

    We have undertaken a combined theoretical and experimental effort directed toward the examination of both the ground and defect states in halide-bridged mixed-valence metal linear chains materials as they are tuned within and between broken symmetry phases. Novel low-dimensional highly correlated electronic materials offer a difficult theoretical challenge as we must span from a description of electronic structure on a molecular scale to the meso scale structure that is intrinsic to these solids. Our theoretical effort at Los Alamos combines quantum chemistry, band structure calculations, and many body modeling using Peierls-Hubbard Hamiltonians in order to model ground and local states. The experimental effort combines synthesis and a variety of microscopic structural and spectroscopic probes and macroscopic measurements in an effort to fully characterize both ground and local states as these materials are tuned in the phase boundary regions between broken symmetry states. The present article summarizes some of our recent research using optical spectroscopy to obtain signatures of photoexcited and intrinsic local states and compares these experimental results with Peierls-Hubbard calculations of the optical properties of these materials. Details concerning the theoretical and experimental approaches can be found elsewhere.

  5. INFLUENCE OF THE GAS-DENSITY ON THE GAS ENTRAINMENT RATE AND GAS HOLD-UP IN LOOP-VENTURI REACTORS

    NARCIS (Netherlands)

    CRAMERS, PHMR; VANDIERENDONCK, LL; BEENACKERS, AACM

    1992-01-01

    The hydrodynamics of a loop-venturi reactor were investigated using a downflow liquid jet ejector. Both the gas entrainment rate of the ejector and the gas hold-up in the main holding vessel were shown to be influenced by the gas density. The amount of volumetrically entrained gas as well as the gas

  6. INFLUENCE OF THE GAS-DENSITY ON THE GAS ENTRAINMENT RATE AND GAS HOLD-UP IN LOOP-VENTURI REACTORS

    NARCIS (Netherlands)

    CRAMERS, PHMR; VANDIERENDONCK, LL; BEENACKERS, AACM

    1992-01-01

    The hydrodynamics of a loop-venturi reactor were investigated using a downflow liquid jet ejector. Both the gas entrainment rate of the ejector and the gas hold-up in the main holding vessel were shown to be influenced by the gas density. The amount of volumetrically entrained gas as well as the gas

  7. Topological Model on the Inductive Effect in Alkyl Halides Using Local Quantum Similarity and Reactivity Descriptors in the Density Functional Theory

    Directory of Open Access Journals (Sweden)

    Alejandro Morales-Bayuelo

    2014-01-01

    Full Text Available We present a topological analysis to the inductive effect through steric and electrostatic scales of quantitative convergence. Using the molecular similarity field based in the local guantum similarity (LQS with the Topo-Geometrical Superposition Algorithm (TGSA alignment method and the chemical reactivity in the density function theory (DFT context, all calculations were carried out with Amsterdam Density Functional (ADF code, using the gradient generalized approximation (GGA and local exchange correlations PW91, in order to characterize the electronic effect by atomic size in the halogens group using a standard Slater-type-orbital basis set. In addition, in this study we introduced news molecular bonding relationships in the inductive effect and the nature of the polar character in the C–H bond taking into account the global and local reactivity descriptors such as chemical potential, hardness, electrophilicity, and Fukui functions, respectively. These descriptors are used to find new alternative considerations on the inductive effect, unlike to the binding energy and dipole moment performed in the traditional organic chemical.

  8. NMR shielding tensors for density fitted local second-order Møller-Plesset perturbation theory using gauge including atomic orbitals.

    Science.gov (United States)

    Loibl, Stefan; Schütz, Martin

    2012-08-28

    An efficient method for the calculation of nuclear magnetic resonance (NMR) shielding tensors is presented, which treats electron correlation at the level of second-order Mo̸ller-Plesset perturbation theory. It uses spatially localized functions to span occupied and virtual molecular orbital spaces, respectively, which are expanded in a basis of gauge including atomic orbitals (GIAOs or London atomic orbitals). Doubly excited determinants are restricted to local subsets of the virtual space and pair energies with an interorbital distance beyond a certain threshold are omitted. Furthermore, density fitting is employed to factorize the electron repulsion integrals. Ordinary Gaussians are employed as fitting functions. It is shown that the errors in the resulting NMR shielding constant, introduced (i) by the local approximation and (ii) by density fitting, are very small or even negligible. The capabilities of the new program are demonstrated by calculations on some extended molecular systems, such as the cyclobutane pyrimidine dimer photolesion with adjacent nucleobases in the native intrahelical DNA double strand (ATTA sequence). Systems of that size were not accessible to correlated ab initio calculations of NMR spectra before. The presented method thus opens the door to new and interesting applications in this area.

  9. Time-dependent density-functional theory simulation of local currents in pristine and single-defect zigzag graphene nanoribbons

    Science.gov (United States)

    He, Shenglai; Russakoff, Arthur; Li, Yonghui; Varga, Kálmán

    2016-07-01

    The spatial current distribution in H-terminated zigzag graphene nanoribbons (ZGNRs) under electrical bias is investigated using time-dependent density-functional theory solved on a real-space grid. A projected complex absorbing potential is used to minimize the effect of reflection at simulation cell boundary. The calculations show that the current flows mainly along the edge atoms in the hydrogen terminated pristine ZGNRs. When a vacancy is introduced to the ZGNRs, loop currents emerge at the ribbon edge due to electrons hopping between carbon atoms of the same sublattice. The loop currents hinder the flow of the edge current, explaining the poor electric conductance observed in recent experiments.

  10. ELECTRON-CAPTURE AND β-DECAY RATES FOR sd-SHELL NUCLEI IN STELLAR ENVIRONMENTS RELEVANT TO HIGH-DENSITY O–NE–MG CORES

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Toshio [Department of Physics and Graduate School of Integrated Basic Sciences, College of Humanities and Sciences, Nihon University Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan); Toki, Hiroshi [Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047 (Japan); Nomoto, Ken’ichi, E-mail: suzuki@phys.chs.nihon-u.ac.jp [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)

    2016-02-01

    Electron-capture and β-decay rates for nuclear pairs in the sd-shell are evaluated at high densities and high temperatures relevant to the final evolution of electron-degenerate O–Ne–Mg cores of stars with initial masses of 8–10 M{sub ⊙}. Electron capture induces a rapid contraction of the electron-degenerate O–Ne–Mg core. The outcome of rapid contraction depends on the evolutionary changes in the central density and temperature, which are determined by the competing processes of contraction, cooling, and heating. The fate of the stars is determined by these competitions, whether they end up with electron-capture supernovae or Fe core-collapse supernovae. Since the competing processes are induced by electron capture and β-decay, the accurate weak rates are crucially important. The rates are obtained for pairs with A = 20, 23, 24, 25, and 27 by shell-model calculations in the sd-shell with the USDB Hamiltonian. Effects of Coulomb corrections on the rates are evaluated. The rates for pairs with A = 23 and 25 are important for nuclear Urca processes that determine the cooling rate of the O–Ne–Mg core, while those for pairs with A = 20 and 24 are important for the core contraction and heat generation rates in the core. We provide these nuclear rates at stellar environments in tables with fine enough meshes at various densities and temperatures for studies of astrophysical processes sensitive to the rates. In particular, the accurate rate tables are crucially important for the final fates of not only O–Ne–Mg cores but also a wider range of stars, such as C–O cores of lower-mass stars.

  11. A closed-form solution for moving source localization using LBI changing rate of phase difference only

    Directory of Open Access Journals (Sweden)

    Zhang Min

    2014-04-01

    Full Text Available Due to the deficiencies in the conventional multiple-receiver localization systems based on direction of arrival (DOA such as system complexity of interferometer or array and amplitude/phase unbalance between multiple receiving channels and constraint on antenna configuration, a new radiated source localization method using the changing rate of phase difference (CRPD measured by a long baseline interferometer (LBI only is studied. To solve the strictly nonlinear problem, a two-stage closed-form solution is proposed. In the first stage, the DOA and its changing rate are estimated from the CRPD of each observer by the pseudolinear least square (PLS method, and then in the second stage, the source position and velocity are found by another PLS minimization. The bias of the algorithm caused by the correlation between the measurement matrix and the noise in the second stage is analyzed. To reduce this bias, an instrumental variable (IV method is derived. A weighted IV estimator is given in order to reduce the estimation variance. The proposed method does not need any initial guess and the computation is small. The Cramer–Rao lower bound (CRLB and mean square error (MSE are also analyzed. Simulation results show that the proposed method can be close to the CRLB with moderate Gaussian measurement noise.

  12. Retardations in fault creep rates before local moderate earthquakes along the San Andreas fault system, central California

    Science.gov (United States)

    Burford, R.O.

    1988-01-01

    Records of shallow aseismic slip (fault creep) obtained along parts of the San Andreas and Calaveras faults in central California demonstrate that significant changes in creep rates often have been associated with local moderate earthquakes. An immediate postearthquake increase followed by gradual, long-term decay back to a previous background rate is generally the most obvious earthquake effect on fault creep. This phenomenon, identified as aseismic afterslip, usually is characterized by above-average creep rates for several months to a few years. In several cases, minor step-like movements, called coseismic slip events, have occurred at or near the times of mainshocks. One extreme case of coseismic slip, recorded at Cienega Winery on the San Andreas fault 17.5 km southeast of San Juan Bautista, consisted of 11 mm of sudden displacement coincident with earthquakes of ML=5.3 and ML=5.2 that occurred 2.5 minutes apart on 9 April 1961. At least one of these shocks originated on the main fault beneath the winery. Creep activity subsequently stopped at the winery for 19 months, then gradually returned to a nearly steady rate slightly below the previous long-term average. The phenomena mentioned above can be explained in terms of simple models consisting of relatively weak material along shallow reaches of the fault responding to changes in load imposed by sudden slip within the underlying seismogenic zone. In addition to coseismic slip and afterslip phenomena, however, pre-earthquake retardations in creep rates also have been observed. Onsets of significant, persistent decreases in creep rates have occurred at several sites 12 months or more before the times of moderate earthquakes. A 44-month retardation before the 1979 ML=5.9 Coyote Lake earthquake on the Calaveras fault was recorded at the Shore Road creepmeter site 10 km northwest of Hollister. Creep retardation on the San Andreas fault near San Juan Bautista has been evident in records from one creepmeter site for

  13. High-Dose-Rate Interstitial Brachytherapy as Monotherapy for Clinically Localized Prostate Cancer: Treatment Evolution and Mature Results

    Energy Technology Data Exchange (ETDEWEB)

    Zamboglou, Nikolaos [Department of Radiation Oncology, Klinikum Offenbach, Offenbach (Germany); Tselis, Nikolaos, E-mail: ntselis@hotmail.com [Department of Radiation Oncology, Klinikum Offenbach, Offenbach (Germany); Baltas, Dimos [Department of Medical Physics and Engineering, Klinikum Offenbach, Offenbach (Germany); Buhleier, Thomas [Department of Radiation Oncology, Klinikum Offenbach, Offenbach (Germany); Martin, Thomas [Department of Radiation Oncology, Klinikum Bremen-Mitte, Bremen (Germany); Milickovic, Natasa; Papaioannou, Sokratis [Department of Medical Physics and Engineering, Klinikum Offenbach, Offenbach (Germany); Ackermann, Hanns [Institute of Biostatistics, J.W. Goethe University of Frankfurt, Frankfurt (Germany); Tunn, Ulf W. [Department of Urology, Klinikum Offenbach, Offenbach (Germany)

    2013-03-01

    Purpose: To report the clinical outcome of high-dose-rate (HDR) interstitial (IRT) brachytherapy (BRT) as sole treatment (monotherapy) for clinically localized prostate cancer. Methods and Materials: Between January 2002 and December 2009, 718 consecutive patients with clinically localized prostate cancer were treated with transrectal ultrasound (TRUS)-guided HDR monotherapy. Three treatment protocols were applied; 141 patients received 38.0 Gy using one implant in 4 fractions of 9.5 Gy with computed tomography-based treatment planning; 351 patients received 38.0 Gy in 4 fractions of 9.5 Gy, using 2 implants (2 weeks apart) and intraoperative TRUS real-time treatment planning; and 226 patients received 34.5 Gy, using 3 single-fraction implants of 11.5 Gy (3 weeks apart) and intraoperative TRUS real-time treatment planning. Biochemical failure was defined according to the Phoenix consensus, and toxicity was evaluated using Common Toxicity Criteria for Adverse Events version 3. Results: The median follow-up time was 52.8 months. The 36-, 60-, and 96-month biochemical control and metastasis-free survival rates for the entire cohort were 97%, 94%, and 90% and 99%, 98%, and 97%, respectively. Toxicity was scored per event, with 5.4% acute grade 3 genitourinary and 0.2% acute grade 3 gastrointestinal toxicity. Late grade 3 genitourinary and gastrointestinal toxicities were 3.5% and 1.6%, respectively. Two patients developed grade 4 incontinence. No other instance of grade 4 or greater acute or late toxicity was reported. Conclusion: Our results confirm IRT-HDR-BRT is safe and effective as monotherapy for clinically localized prostate cancer.

  14. Distinct Correlation Structure Supporting a Rate-Code for Sound Localization in the Owl’s Auditory Forebrain

    Science.gov (United States)

    2017-01-01

    Abstract While a topographic map of auditory space exists in the vertebrate midbrain, it is absent in the forebrain. Yet, both brain regions are implicated in sound localization. The heterogeneous spatial tuning of adjacent sites in the forebrain compared to the midbrain reflects different underlying circuitries, which is expected to affect the correlation structure, i.e., signal (similarity of tuning) and noise (trial-by-trial variability) correlations. Recent studies have drawn attention to the impact of response correlations on the information readout from a neural population. We thus analyzed the correlation structure in midbrain and forebrain regions of the barn owl’s auditory system. Tetrodes were used to record in the midbrain and two forebrain regions, Field L and the downstream auditory arcopallium (AAr), in anesthetized owls. Nearby neurons in the midbrain showed high signal and noise correlations (RNCs), consistent with shared inputs. As previously reported, Field L was arranged in random clusters of similarly tuned neurons. Interestingly, AAr neurons displayed homogeneous monotonic azimuth tuning, while response variability of nearby neurons was significantly less correlated than the midbrain. Using a decoding approach, we demonstrate that low RNC in AAr restricts the potentially detrimental effect it can have on information, assuming a rate code proposed for mammalian sound localization. This study harnesses the power of correlation structure analysis to investigate the coding of auditory space. Our findings demonstrate distinct correlation structures in the auditory midbrain and forebrain, which would be beneficial for a rate-code framework for sound localization in the nontopographic forebrain representation of auditory space. PMID:28674698

  15. On the errors of local density (LDA) and generalized gradient (GGA) approximations to the Kohn-Sham potential and orbital energies.

    Science.gov (United States)

    Gritsenko, O V; Mentel, Ł M; Baerends, E J

    2016-05-28

    In spite of the high quality of exchange-correlation energies Exc obtained with the generalized gradient approximations (GGAs) of density functional theory, their xc potentials vxc are strongly deficient, yielding upshifts of ca. 5 eV in the orbital energy spectrum (in the order of 50% of high-lying valence orbital energies). The GGAs share this deficiency with the local density approximation (LDA). We argue that this error is not caused by the incorrect long-range asymptotics of vxc or by self-interaction error. It arises from incorrect density dependencies of LDA and GGA exchange functionals leading to incorrect (too repulsive) functional derivatives (i.e., response parts of the potentials). The vxc potential is partitioned into the potential of the xc hole vxchole (twice the xc energy density ϵxc), which determines Exc, and the response potential vresp, which does not contribute to Exc explicitly. The substantial upshift of LDA/GGA orbital energies is due to a too repulsive LDA exchange response potential vxresp (LDA) in the bulk region. Retaining the LDA exchange hole potential plus the B88 gradient correction to it but replacing the response parts of these potentials by the model orbital-dependent response potential vxresp (GLLB) of Gritsenko et al. [Phys. Rev. A 51, 1944 (1995)], which has the proper step-wise form, improves the orbital energies by more than an order of magnitude. Examples are given for the prototype molecules: dihydrogen, dinitrogen, carbon monoxide, ethylene, formaldehyde, and formic acid.

  16. Plasmodium falciparum merozoite surface protein 1 - Glycosylation and localization to low-density, detergent-resistant membranes in the parasitized erythrocyte

    DEFF Research Database (Denmark)

    Hoessli, D.C.; Poincelet, M.; Gupta, Ramneek;

    2003-01-01

    In addition to the major carbohydrate moieties of the glycosylphosphatidylinositol (GPI) anchor, we report that Plasmodium falciparum merozoite surface protein 1 (MSP-1) bears O-GlcNAc modifications predominantly in beta-anomeric configuration, in both the C- and N-terminal portions of the protein....... Subcellular fractionation of parasitized erythrocytes in the late trophozoite/schizont stage reveals that GPI-anchored C-terminal fragments of MSP-1 are recovered in Triton X-100 resistant, low-density membrane fractions. Our results suggest that O -GlcNAc-modified MSP-1 N-terminal fragments tend to localize...... within the parasitophorous vacuolar membrane while GPI-anchored MSP-1 C-terminal fragments associate with low-density, Triton X-100 resistant membrane domains (rafts), redistribute in the parasitized erythrocyte and are eventually shed as membrane vesicles that also contain the endogenous, GPI-linked CD...

  17. Adaptation to local thermal regimes by crustose coralline algae does not affect rates of recruitment in coral larvae

    Science.gov (United States)

    Siboni, Nachshon; Abrego, David; Evenhuis, Christian; Logan, Murray; Motti, Cherie A.

    2015-12-01

    Crustose coralline algae (CCA) are well known for their ability to induce settlement in coral larvae. While their wide distribution spans reefs that differ substantially in temperature regimes, the extent of local adaptation to these regimes and the impact they have on CCA inductive ability are unknown. CCA Porolithon onkodes from Heron (southern) and Lizard (northern) islands on Australia's Great Barrier Reef (separated by 1181 km) were experimentally exposed to acute or prolonged thermal stress events and their thermal tolerance and recruitment capacity determined. A sudden onset bleaching model was developed to determine the health status of CCA based on the rate of change in the CCA live surface area (LSA). The interaction between location and temperature was significant ( F (2,119) = 6.74, p = 0.0017), indicating that thermally driven local adaptation had occurred. The southern population remained healthy after prolonged exposure to 28 °C and exhibited growth compared to the northern population ( p = 0.022), with its optimum temperature determined to be slightly below 28 °C. As expected, at the higher temperatures (30 and 32 °C) the Lizard Island population performed better that those from Heron Island, with an optimum temperature of 30 °C. Lizard Island CCA displayed the lowest bleaching rates at 30 °C, while levels consistently increased with temperature in their southern counterparts. The ability of those CCA deemed thermally tolerant (based on LSA) to induce Acropora millepora larval settlement was then assessed. While spatial differences influenced the health and bleaching levels of P. onkodes during prolonged and acute thermal exposure, thermally tolerant fragments, regardless of location, induced similar rates of coral larval settlement. This confirmed that recent thermal history does not influence the ability of CCA to induce settlement of A. millepora larvae.

  18. Creatine kinase rate constant in the human heart measured with 3D‐localization at 7 tesla

    Science.gov (United States)

    Robson, Matthew D.; Neubauer, Stefan; Rodgers, Christopher T.

    2016-01-01

    Purpose We present a new Bloch‐Siegert four Angle Saturation Transfer (BOAST) method for measuring the creatine kinase (CK) first‐order effective rate constant kf in human myocardium at 7 tesla (T). BOAST combines a variant of the four‐angle saturation transfer (FAST) method using amplitude‐modulated radiofrequency pulses, phosphorus Bloch‐Siegert B1+‐mapping to determine the per‐voxel flip angles, and nonlinear fitting to Bloch simulations for postprocessing. Methods Optimal flip angles and repetition time parameters were determined from Monte Carlo simulations. BOAST was validated in the calf muscle of two volunteers at 3T and 7T. The myocardial CK forward rate constant was then measured in 10 volunteers at 7T in 82 min (after 1H localization). Results BOAST kfCK values were 0.281 ± 0.002 s−1 in the calf and 0.35 ± 0.05 s−1 in myocardium. These are consistent with literature values from lower fields. Using a literature values for adenosine triphosphate concentration, we computed CK flux values of 4.55 ± 1.52 mmol kg−1 s−1. The sensitive volume for BOAST depends on the B1 inhomogeneity of the transmit coil. Conclusion BOAST enables measurement of the CK rate constant in the human heart at 7T, with spatial localization in three dimensions to 5.6 mL voxels, using a 10‐cm loop coil. Magn Reson Med 78:20–32, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:27579566

  19. Semi-analytical quasi-normal mode theory for the local density of states in coupled photonic crystal cavity-waveguide structures

    DEFF Research Database (Denmark)

    de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper

    2015-01-01

    We present and validate a semi-analytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained......, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities a non...

  20. Local Quasiparticle Density of States of Superconducting SmFeAsO1-xFx Single Crystals: Evidence for Spin-Mediated Pairing

    Science.gov (United States)

    Fasano, Y.; Maggio-Aprile, I.; Zhigadlo, N. D.; Katrych, S.; Karpinski, J.; Fischer, Ø.

    2010-10-01

    We probe the local quasiparticles density of states in micron-sized SmFeAsO1-xFx single crystals by means of scanning tunnelling spectroscopy. Spectral features resemble those of cuprates, particularly a dip-hump-like structure developed at energies larger than the gap that can be ascribed to the coupling of quasiparticles to a collective mode, quite likely a resonant spin mode. The energy of the collective mode revealed in our study decreases when the pairing strength increases. Our findings support spin-fluctuation-mediated pairing in pnictides.